121st Advisory Committee on Nuclear Waste (ACNW) Meeting, September 20, 2000
UNITED STATES OF AMERICA
NUCLEAR REGULATORY COMMISSION
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ADVISORY COMMITTEE ON NUCLEAR WASTE
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121ST ACNW MEETING
PUBLIC MEETING
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Ballroom B
Crowne Plaza Hotel
Las Vegas, Nevada
Wednesday, September 20, 2000
The Commission met in open session, pursuant to
notice, at 8:00 a.m., B. John Garrick, Chairman, presiding.
COMMITTEE MEMBERS PRESENT:
DR. B. JOHN GARRICK, Chairman, ACNW
DR. RAYMOND G. WYMER, Vice Chairman, ACNW
MR. MILTON N. LEVENSON, ACNW Member
DR. GEORGE HORNBERGER, ACNW Member. STAFF AND PARTICIPANTS:
DR. JOHN T. LARKINS, Executive Director, ACRS/ACNW
MR. HOWARD LARSON, Acting Associated Director, ACRS/ACNW
MR. RICHARD K. MAJOR,, ACNW Staff
MS. LYNN DEERING, ACNW Staff
MR. AMARJIT SINGH, ACNW Staff
DR. ANDREW C. CAMPBELL, ACNW Staff
JAMES E. LYONS
NEIL COLEMAN, NMSS
WILLIAM REAMER, NMSS
DR. JOHN TRAPP, NMSS. P R O C E E D I N G S
[8:00 a.m.]
MR. GARRICK: Good morning. The meeting will now
come to order. We welcome Jim Lyons, joining us on the
staff side of the table, the new Director for Technical
Support for the ACRS and ACNW.
MR. LYONS: Thank you. I'm glad to be here.
MR. GARRICK: Good. This is the second day of the
121st meeting of the Advisory Committee on Nuclear Waste.
My name is John Garrick, Chairman of the ACNW.
Other members of the committee include George Hornberger,
Ray Wymer, and Milt Levenson.
The entire meeting will be open to the public.
Today, the committee will hear a project overview
from the Department of Energy; a Department of Energy
representative on Yucca Mountain will give a status report
on the site recommendation consideration report from DOE;
discuss major aspects of the total performance, system
performance assessment, the site recommendations version;
hear an update on chlorine-36 from DOE and the M&O; discuss
the results of ongoing studies on the fluid inclusion issue
from a panel composed of representatives of University of
Nevada-Las Vegas, DOE, and the state; and, review relevant
activities and status of site tour scheduled for tomorrow.
We'll also continue to work on preparation for the
meeting that the committee has with the Commission,
originally scheduled for October 17, now rescheduled for
December 18. At that meeting, we intend to discuss such
issues as site sufficiency review, risk-informed regulation
in NMSS, Part 71, ACNW action plan and priority topics, and
we will also discuss the recent trip taken by ACNW to
England and France.
Andy Campbell is the Designated Federal Official
for the initial portion of today's meeting.
This meeting is being conducted in accordance with
the provisions of the Federal Advisory Committee Act.
We have received one request from a member of the
public regarding today's session. Mr. Corbin Harney, who
spoke to us yesterday, wants a few more moments. I'm
suggesting that we maybe do that just before the break this
morning. And if others of you wish to make comments, please
contact a member of the staff.
Also, please use one of the microphones, identify
yourself, and speak clearly.
Okay. With that, I think we'll jump right into
the first presentation. I'm going to ask each of the
speakers to introduce themselves, tell us what their
positions are and organizations and what have you.
MR. DYER: Good morning. I'm Russ Dyer. I'm
DOE's Project Manager at Yucca Mountain and I can't tell you
what a delight it is to be here this morning. I just
finished a three-week detail in Washington, got in last
night.
Next slide, please.
I'm going to give a quick overview. There are
about six topics that we're going to go through, look at a
little at the project accomplishments over the past year,
design evolution, the role of the site recommendation
consideration report, the progress that we're making toward
the closure of the NRC key technical issues.
My understanding is I think that was gone over in
considerable detail yesterday, so I'm just going to hit the
highlights.
Integrated safety management system is an
initiative that is going on across the Department of Energy
throughout the complex. We are finishing up our last phase
validation this week on that. That is something that has
taken a lot of energies, just to tell you a little bit about
that, and then a quick project outlook, what lies ahead of
us here.
Next slide, please. Accomplishments. Next slide.
If we look at the general schedule of things here,
running out through the site recommendation and its
associated final environmental impact statement and then
further on out to the license application and eventually
operations.
We have put the draft environmental impact
statement on the street. We've had public hearings on that.
The next major activity that's called for in the Nuclear
Waste Policy Act is the site recommendation.
We are putting out a site recommendation
consideration report this fall/winter which lays out the
technical basis at this point in time to support and
underlie that site recommendation decision.
Next slide, please.
The things that we got done so far in 2000.
Underlying the site recommendation consideration report are
a series of process level model reports and then below those
lie the what are called AMRs, analysis and model reports.
I'll show you a diagram in a little while which shows the
cascading hierarchy of technical supporting documents, all
of which get summarized up into a site recommendation
consideration report and then finally built into the site
recommendation.
There are nine process model reports. We have
accepted seven of them unconditionally. The remaining two
PMRs have been accepted with conditions. There were 121
supporting lower level, more detailed analysis and model
reports, 119 of those have been completed.
On the design side, the pertinent document there
is called an SDD, the system description document. There
are 24 of those that lie within our plans. All of those
have been -- 24 that are needed to support SRCR. There are
others that will be needed eventually to support the license
application, and those have a further finer level of detail
in the engineering analyses and 34 of those have been
completed.
If you have been following the repository safety
strategy, about a year ago, we determined that we had
focused entirely on the post-closure. We needed also to put
in a pre-closure element of the repository safety strategy
and we've completed a preliminary cut at the pre-closure
safety assessment.
The total system performance assessment for the
site recommendation has been completed. Bob Andrews will
talk to you much more about that, and about the base case
calculations for the TSPA-SR and the sensitivity
calculations that have been completed and are also in
progress.
Next slide, please.
In the testing arena, and Mark Peters will talk to
you in considerably more depth about this and we'll see more
of it tomorrow, we've started hydraulic testing in the
luvium single well pump test, that's been initiated in one
of the Nye County holes down in the south of Yucca Mountain.
We should start multi-well testing and tracer testing in
'02.
Within the frost drift hydraulic properties and
seepage testing has been initiated in the lower lith, lower
lithofizal unit. That's primarily in -- that would be in
niche five. The drift-to-drift seepage test is underway in
alcove eight.
And yesterday, I believe, although I didn't hear
confirmation, we turned on a test over at the Atlas
facility, over on Locie Road, an engineered barrier system
ventilation model test. It's a scale model of surrogate
waste packages that have heaters in them and we're looking
to validate our models to look at how ventilation can remove
heat from that system.
And the geo technical investigation of north portal surface
facility is underway. This is to provide us more
information in the seismic design arena.
Next slide, please.
Data and software qualification progress. The
commitment was that we would have 80 percent of our data and
software qualified at the time of the SRCR. We're well on
the way there. We're actually over the target with the
software qualification. We've got a little bit to go with
the data qualification.
Our draft rule for the replacement to 10 CFR 960,
10 CFR 963, we went through the public hearing process on
that. There was a draft final rule that we've submitted to
NRC for concurrence back in May and, of course, that's all
tied into the 197 and 63 issue.
Planning process. Of course, like most -- well,
every other DOE agency, we're anxiously awaiting Congress to
work on the appropriation. There is supposed to be a
conference committee scheduled for today and I'm hopeful
that by the end of today, we'll have an idea of what our
budget for 2001 will be.
Of course, we've done planning based on
assumptions. We have a lot of stuff that we would like to
do. It does not look like that we will be able to bring in
the entire 437.5 million dollars that the Administration
requested for the project and the program for this year, but
it will be reasonably close, I hope.
Of course, that's the caveat at the bottom. We
have a lot of plans, but you can only do what you can afford
to do.
Next slide.
Design evolution. The design has evolved somewhat
since the EDA-2 design of a couple of years ago. One of the
major changes is as we looked at the waste stream inventory
coming in, the waste stream, in general, is somewhat hotter
because there's higher burn-up fuel as part of the waste
stream.
Whenever we reevaluated the heat that was in the
system, of course, one of the requirements that we have on
the system is a maximum 350 degree Centigrade centerline
temperature in the waste packages, so that the cladding is
not subjected to unzipping.
And when we looked at the effects of the blanket,
the thermal blanket that would be put in if you put in
backfill, it looked like we would violate that.
So part of the exercise that we've done over the
past year is looking at updating the design to remove the
backfill, which, of course, gives you a system which then
could be ventilated for a considerable period of time.
This is just a schematic of what we're looking at
now with, again, the horizontal cylinders emplaced on
pylons. We now have a drip shield that is part of the
system. The drip shield is of titanium, a titanium alloy.
The material for the waste package is still a
nickel alloy corrosion resistant material on the outside,
with, I believe, a stainless steel, essentially a structural
material on the inside.
Other things, we've gone away from a concrete
lining in the emplacement drifts which we had several years
ago. Right now, the ground support is just structural
steel.
Next slide, please.
The design, of course, has not been static,
continues to design, continues to evolve. Looking at the
underground, there are a couple of variables that we can
play with reasonably simply. Whenever we talk about design,
it's really a combination of design and operational
parameters that you can look at juggling.
For instance, you can take the same design, that
is, waste package design, the same emplacement drift
specifications as far as diameter spacing, ground support
that you use, and you can operate that system in different
ways by either varying the spacing between the waste
packages, so tailoring the line thermal load within the
emplacement drifts, or by using combinations of active and
passive ventilation for various periods of time, you can
adjust and control how much heat the system will put into
the rock mass.
That's been, as you're undoubtedly aware, an issue
that the Nuclear Waste Technical Review Board, for one, has
been concerned about. It's also one that the U.S.
Geological Survey expressed concern about in the Director's
review of the viability assessment a couple of years ago.
So looking at different ways that one can approach
the management of heat in the system is something that we're
doing now.
The current reference design has moved the
emplacement drifts somewhat further apart, about twice as
far apart, about 81 meters apart, and would allow the rock
mass, the drift walls to heat up above boiling for some
distance away from the surface of the emplacement drifts,
perhaps maybe ten to 15 meters.
And looking at what it takes if we were to try to
bring this whole system to a below boiling design, we're
still evaluating what it would take to do that and what you
would gain from such a change.
Next slide, please.
TSPA-SR, the TSPA to support the site
recommendation, will incorporate the no backfill reference
design in the base case analysis. That's a change that
we're moving to, and I believe that either Bob or Abe will
talk about some of this, looking at the sensitivity studies
that are associated with that.
We will -- the current plan is to maintain the
reference design, an above boiling operational mode and
design is the base case, and look at sensitivity analysis
from the TSPA to try to understand what are the pros and
cons of various approaches.
Next slide, please.
The site recommendation consideration report.
This is not a pitch for pyramid power or anything, but it is
an attempt to try to lay out, at least graphically, the
hierarchical structure of the thing that sits at the top,
which is eventually a national action, the Secretary's
action, and then the supporting documents that make up part
of the package that go to these higher levels, the Secretary
and the President, to support a decision.
The site recommendation consideration report
currently consists of two volumes. Volume I is an update of
what we know and how TSPA works. Volume II is a preliminary
suitability evaluation.
Eventually, the full site recommendation must have
many other things in it that are called out by law,
including comments from the state and affected counties and
Native American Indian tribes.
Sitting below these two volumes of the site
recommendation consideration report are what we would call
the technical basis report. I talked earlier about the
PMRs, the nine process model reports, and then below those
nine PMRs, there are, I believe, it's 122 of the analysis
and modeling reports, the engineering analysis.
All of that makes up hundreds of thousands of
pages of reference material that is referenced or pointed to
by these higher level documents.
Our intent has been to try to put this together in
an integrated manner. The way we chose to do this is we're
going for a web-based approach on this, with hypertext
links. So one could go to a document and eventually be able
to go from a citation in the document, directly plunge down
into the reference citation. It's going to take us a while,
I think, to get to that.
Next slide, please.
The role of the site recommendation consideration
report. It is not a document that is called for by
legislation. But the Nuclear Waste Policy Act does call for
the DOE to hold public hearings to receive residents'
comments on DOE's consideration of a possible site
recommendation action.
And we wanted to put something reasonably recent,
the last big document we had was the viability assessment,
we wanted to put something reasonably recent on the street
that could inform this dialogue and comments for the public
hearings, and that's where the site -- the idea for the site
recommendation consideration report came from.
We are still on schedule for releasing it in late
2000. The intent is to summarize the technical basis and to
facilitate the public review and comment process.
The technical basis documents, all the bottom of
the pyramid, almost all of that is going to also form the
technical basis for the license application. So we have
encouraged certainly the Nuclear Regulatory Commission, as
they are looking at the basis for sufficiency comments on
the body of work that DOE has done, to not confine
themselves to just looking at the SRCR, but to also look at
the other documents, the PMRs, the AMRs, and down to the
individual lower level reports.
Next slide, please.
And that was a proposal that we proposed to the
NRC back November of last year. NRC agreed in principal to
this proposed approach. So far, we've provided seven of the
nine PMRs to the NRC staff and 119 of the 121 supporting
AMRs, and 11 of the SDDs have been provided.
Some of the documents that we have currently in
review within DOE, the TSPA Rev. 0 and the Yucca Mountain
site description, an update of that. So we will get those,
I hope, on the street here within the next four to six weeks
and those will also support this technical basis that we're
building.
Next slide, please.
Progress toward closure of NRC KTIs.
Next slide.
We've had three meetings, each on one of the KTI
areas, since August, got a couple more planned. I know that
we've got five more that we need to get planned. Those have
been -- I'm very encouraged by the progress on those. We've
been able to either close or close pending virtually every
issue that has been put up, which means that between the
information knowledge that's known now and the plans that
are provided essentially as a promissory note for things
that will be done over the next period of time before the
license application, those have been acceptable to NRC staff
as a reasonable path forward.
Of course, there is no guarantee that the answers
that you get and work that has not been done yet is going to
turn out the way you think it will now.
Next slide, please.
The sub-issues. As I said, this has allowed us to
take almost all of the sub-issues that were examined in the
three meetings to date and either close them or close them
pending. The agreements that have been reached help us
define a path forward for issue closure and we're -- my
understanding is that we proposed dates for the technical
exchange on the remaining KTIs. The intent, of course, is
to get those done.
I think the last meeting that we have scheduled is
February on TSPA, if I remember right, and the intent is to
get everything in hand well before that date.
Next slide, please.
Integrated safety management system, and this is a
very large effort within the Department of Energy, and it is
an attempt to bring what I would call disciplined process
and integrated management across the entire spectrum of
things that DOE is involved in.
Instead of just having nuclear quality assurance
and nuclear safety and having a different culture and a
different program for other aspects of safety, the intent is
to bring one safety system umbrella over all that goes on
within the department.
For years, within the department, we have been
sort of victimized by a series of almost independent
programs that have competed for resources, rather than
putting a single program in place that really helps you
define across the whole spectrum of your programs,
everything that's going on; helps you prioritize it, helps
you identify where the safety risks are, and dedicated
appropriate resources to the most important things.
So this has been a very good exercise for us and
we are in the last phases of that and I would hope by the
end of this week we'll be able to put our name on the wall
and say that we are moving forward in this. This is not a
one-time endeavor, however. It's one of these things that
is based on the concept of continuous improvement. So once
you have essentially your basic system in place, the charge
and challenge is to continue to improve that system year
after year after year.
Next slide, please.
Phase one verification. We had no discrepancies.
We had six opportunities for improvement. Those are listed
here. One noteworthy practice, the worker involvement. The
workers, especially at the site, have really embraced this
program and have made it the success that it is.
When told that they could stop work if they
thought that there was an unsafe environment or a lack of
adequate planning prior to implementing some activity, this
really energized them and they have assumed absolute
ownership of this program.
It's great and you will see that tomorrow, I
think. You will see the pride and the ownership of the
safety program on the part of everybody who works on the
program.
The phase two verification, the way it breaks out,
phase one is that you have the paper in place. Phase two is
that you can demonstrate that you are implementing the
program that's on that paper.
So the phase two was completed back in July. We
are currently in the middle of -- I'm sorry -- the phase one
completed back in July. Phase two, we're currently in the
middle of that activity right now and should get that report
from an independent review team this week.
Next slide, please.
Well, the big thing looming on the horizon,
funding uncertainty. The appropriation, as I said, has not
been set. We are holding our fingers to see what comes out
of conference committee today.
There is a considerable discrepancy between the
marks that the House took into the conference and the
Senate. The Administration request was 437.5 million. The
House marked 413, the Senate marked 351. So probably it's
going to be -- the final mark will be somewhere between 351
and 413, I would hope much closer to 413, but any of those
marks is considerably below the mark that the Administration
supported.
As we prioritize the work for the next physical
year and coming physical years, that work supporting the
site recommendation schedule has the highest priority and
what we told the appropriators and the Congressmen was that
at lower funding levels, the site recommendation schedule
may be at risk.
The schedule for licensing milestones is
uncertain. Of course, our highest priority is for the site
recommendation work, and what that does to the work that's
needed to meet these commitments that we're making as part
of the KTI resolution meetings remains to be seen. Some of
those may be stretched out in time somewhat.
Next slide, please.
The SRCR and the technical basis documents below
it continues to have almost all of our energy put into it.
There's an enormous amount of work that has been done to put
together this integrated effort.
We learned an awful lot in the viability
assessment effort and trying to put things together, put the
defensible basis together, and make sure that there was
consistency through all of the program.
But translating those lessons learned into firm
accomplishments has taken a lot of energy. We're putting a
high priority, obviously, on the interactions to close the
KTIs and to support the NRC sufficiency review.
Looking forward to better understand the
sufficiency review process, of course, we're waiting, as
most people are, for 10 CFR 63, 963 and 197 to hit the
street.
The same caveat about funding limitations applies
here. Actually, I think this is almost exactly the same
thing we said on the last slide. Depending on the funding
level, the SR schedule may be at risk and, of course, it can
impact everything downstream from that, including the LA.
Next slide, please. And I believe I've gone
through my last slide here.
So let me, if we have time, I'd be happy to answer
any questions, Mr. Chairman.
MR. GARRICK: Thank you. Would you be willing to
comment on the things that would have to happen for the
design to stop evolving?
MR. DYER: Stop evolving.
MR. GARRICK: Or to fix the design.
MR. DYER: Even if we were to select, say, a point
design concept, design is an evolutionary thing and I can't
imagine it stopping, per se.
MR. GARRICK: What I'm getting at is there is
obviously, in the minds of the experts, some things that
you're looking to achieve, some things that have to happen
before you feel comfortable with the design. We keep
talking about evolving design. As a matter of fact, the
National Academy of Sciences recommended many years ago in
their re-thinking report that you remain flexible, that we
remain a little more flexible in the way in which we're
going to manage the high level waste, up closer to the time
that we have to really do something.
But nevertheless, there comes a point beyond which
you have to make decisions. You have to make that decision
about the design that you're going with.
And I guess what I'm asking, from a design
standpoint, not necessarily from a regulatory standpoint,
but from your own requirements standpoint, what are some of
the key things that you think have to happen in order for
you to be happy with the design?
MR. DYER: If we look at the requirements that a
design must satisfy, first, making clear what those
requirements are, there are technical performance criteria
that must be built in, but there are other criteria that may
revolve around economics, they may revolve around I'll call
it technical credibility.
And some of those we're having a hard time putting
our arms around those about how hard and fast those should
be as requirements, how do you build those into a
requirements document, which you normally thought of as
pretty much performance specifications.
But there are other considerations that may be
just as important as those hard and fast performance
specifications. But that's an area that we're exploring
right now. A program that is technically immaculate, that
costs hundreds of billions of dollars is probably not very
useful for this country.
What's the tradeoff between a program that
adequately protects health and safety of the public and the
workers and a program that the nation can afford and
support?
I suspect I didn't answer your question, because
I'm not all together sure that I know or that anybody knows
what the right answer is.
MR. GARRICK: What I was getting at is where the
focus of attention is. Sometimes I think in the
preoccupation with the regulatory milestones and the various
reports that you have established as goals, it obscures some
of the understanding of what's going on in fact with the
design in terms of what really is important to safety.
Now, we'll get into this more with the performance
assessment, of course, but, also, I think that people, after
you've spent three-plus billion dollars, are beginning to
think that the time ought to be getting close to when a
design ought to be surfacing that you're quite comfortable
with or if you're not comfortable with it, you have a pretty
darn good idea of what it is that it's going to take to meet
these fundamental requirements of safety and performance.
I was just pushing that a little bit in terms of
what were the main issues from the perspective of the
project manager.
Any questions? Milt, have you got any questions?
MR. LEVENSON: No.
MR. GARRICK: Ray?
MR. HORNBERGER: Yes. Russ, if your budget does
come in at, let's say, 413 million, will the SRCR be
released in calendar year 2000?
MR. DYER: That's our current intent, yes.
MR. HORNBERGER: So when you mentioned it might be
winter 2001, that was under a budget constraint scenario.
MR. DYER: Yes. That would be a fairly strong
budget, constrained budget.
MR. HORNBERGER: So for the NRC, you're still
looking for May of '01 to have the comments back.
MR. DYER: I think that's right. I believe --
yes. Right now, we haven't changed anything in the way of
our interactions. That's what the KTI meetings have been
geared for and that is our preferred path.
MR. HORNBERGER: Also, just one small
clarification, if you can clarify for me on the technical
exchanges. Of course, you held the one on the unsaturated
zone in Berkeley, I believe, and you have one coming up in
Albuquerque on the saturated zone.
And your little footnote said that unsaturated
flow is also covered in the saturated zone flow. Is this
just a follow-up from the unsaturated KTI or is there some
part of the unsaturated zone flow that gets lumped into the
saturated zone?
MR. DYER: I'm going to get some help here. I
thought they were lumped together and we just treated them
separately.
MS. HANLON: There are two aspects of that, Dr.
Hornberger. There are two aspects of that. First of all,
the unsaturated zone in Berkeley did not include the matrix
flow for the saturated zone. So that part will be moved
forward to Albuquerque.
The second thing is we will be discussing our
evaluation of additional information on infiltration
regarding the unsaturated zone in Albuquerque and how we're
going to proceed forward to hopefully clothespin that item.
So those are the two things that are put forward.
MR. HORNBERGER: Thank you.
MR. GARRICK: Any questions from the staff?
[No response.]
MR. GARRICK: Thank you very much, Russ. Very
good.
MR. DYER: My pleasure.
MR. GARRICK: Our next presentation will be on the
site recommendation consideration report. It says here
Steve Brokoum, but you don't look like him.
MR. SULLIVAN: No. You have Tim Sullivan instead.
Good morning.
MR. GARRICK: Good morning.
MR. SULLIVAN: Actually, this will be a two-part
presentation. When I'm done, Carol Hanlon will give you a
brief overview, from DOE's perspective, of the sufficiency
interactions that have been conducted to date.
I'm the Team Leader for the Site Regulatory
Products, including the site recommendation.
This is an outline of what I'm going to discuss
here. I'm going to focus here mostly on the contents of
Volume II of the SRCR and I will explain why in a moment,
and then some further schedule information. Some of this is
redundant with what Russ has presented, so I'll move over
those parts quickly.
Current status. The report itself is in DOE
review and it's on schedule for release in late 2000,
calendar year 2000.
An overview of the contents of the site
recommendation consideration report. Volume I of the two
volume report was built around the requirements of the
Nuclear Waste Policy Act, Section 114(a)(1), which requires
three things; a description of the proposed repository, a
description of the waste form and packaging, and a
discussion of the data relating to the safety of the site.
So on the next slide, the Volume I is organized as
follows. It includes, in addition to the information I just
referred to, as a part of Section 4, the discussion of the
data relating to the safety of the site. It includes
TSPA-SR results. It also includes a section on pr-closure
safety assessment. Both of those support Volume II.
And then Volume II itself -- Volume I will be
similar in form and content to the viability assessment;
that is, it is descriptive material and analytical results.
Volume II is somewhat different in that here, DOE
will make a preliminary evaluation of suitability in
accordance with the proposed 963 siting guidelines.
So Volume II is, in fact, organized around the
proposed regulation. Now, I'm going to spend a few minutes
describing to you what the contents of that volume are.
It's actually three parts. The first is an
introduction, the second is the preliminary pre-closure
suitability evaluation, includes a description of the
assessment approach used to achieve safe operations before
closure of the repository, and it will also include a
discussion of the suitability criteria identified in the
regulation.
The focus here is to ensure that the repository
systems limit releases and that we have adequate emergency
planning systems in place or response systems in place.
Then Section 3 is the preliminary post-closure
suitability evaluation. Here, the proposed rule includes
requirements for the TSPA methodology that I will describe.
It calls for DOE to identify natural and engineered features
important to isolating waste, and we will do so.
There are a series of suitability criteria or
characteristics that I will describe. And, finally, it has
release limits to which we will compare the TSPA results for
the 10,000 year compliance period.
So, first, I'm going to describe in a little more
detail Section 2 and then Section 3.
So in Volume II, Section 2, the pre-closure
methodology, the approach that we're taking is to apply
established nuclear technologies, proven technologies, and
using those technologies and established methods for design
and operations; that is, accepted codes and standards.
The assessment approach itself, fundamentally, is
to reduce releases to workers and to the environment.
The approach starts with a systematic
identification of events based on standard hazard
evaluations. It then follows with a screening or a
determination of which events apply to the systems that will
be built at Yucca Mountain and then, finally, these events
are categorized into category one or category two, depending
on their associated probabilities.
Then the consequence analysis is complete, the
preliminary consequence analyses are reported. These
determine the dose for comparison with the limits specified
in the regulation.
Finally, the repository design establishes
criteria for the prevention and mitigation of repository --
repository design establishes criteria for the use of
features and controls important to safety. These are, of
course, to prevent and mitigate consequences.
Now, the suitability criteria in the regulation,
page eight, in these sections, DOE must demonstrate the
ability to contain radioactive material and limit releases
of radioactive materials.
Here, the burden is on DOE to demonstrate that the
radiation doses are below the limits.
Secondly, to implement control and emergency
systems to limit exposure to radiation. Again, DOE will
describe the preliminary program for the emergency systems
and this program will rely on industry standards and proven
technologies.
Ability to maintain a system and components that
perform their intended safety functions. In this section of
Volume II, we will record analyses of structures, systems
and components to ensure that they are performing as
intended.
And, finally, the system design will ensure the
option for retrieval up to 300 years.
In Volume II, the preliminary post-closure
suitability evaluation. Part 963 has a series of
requirements for the TSPA methodology that will be used to
assess post-closure performance for the 10,000 year
compliance period. These requirements are that data related
to the post-closure suitability criteria or characteristics
are incorporated in the TSPA, and I will describe those
characteristics in a moment.
The methodology also must account for
uncertainties both in information and in modeling. It must
demonstrate that alternative models have been considered and
in Volume II, we will summarize the consideration of
alternative models in the TSPA-SR, in the PMRs, and in
Volume I.
It must provide the technical bases for input
parameters, for the FEPS analyses, the features, events and
processes analyses, and for the models used or abstracted
into the TSPA.
Finally, the TSPA must conduct appropriate
sensitivity studies. So Volume II will address each of
these requirements for the TSPA methodology, on page 10.
The rule also calls for DOE to identify the
natural and engineered features that are important to
isolating waste and we will do so. Six natural and
engineered features will be described. These are summarized
from the barrier importance analyses that are in the TSPA-SR
that Bob and Abe will describe in a moment.
First is surficial soils and topography, reduce
the amount of water entering the unsaturated zone for
surficial processes, infiltration is less than
precipitation.
Unsaturated rock layers overlying the repository
and host rock unit reduce the amount of water reaching the
repository. Here, seepage is less than percolation.
Drip shield and inverts surrounding the waste
packages. The drip shield that Russ described, the titanium
drip shield protects the waste package from any seepage that
may enter the drift and there is a ballast placed in the
invert below the waste package in the bottom of the tunnel
that serves to limit advective transport into the host rock.
On page 11, the waste package prevents water from
contacting the waste form for thousands of years based on
the corrosion resistant material that's been selected and
the corrosion testing that the department has completed to
date.
The spent nuclear fuel cladding delays or limits
the water from contacting the actual fuel pellets.
Finally, the waste form itself serves to limit the
contact of water with the nuclear fuel itself, both in the
commercial and the DOE high level waste glass form.
Each of these will be described in Volume II of
the SRCR.
Okay. Another requirement of the rule is for DOE
to evaluate a series of suitability criteria or
characteristics. There are a total of nine here. These
closely parallel the process model reports that the
department has prepared to support the TSPA-SR and Volume II
of the SRCR.
For each of these characteristics, Volume II will
describe the technical basis -- that is, the data -- that's
used in this evaluation. It will describe the models and it
will include a regulatory evaluation of how this information
is represented and incorporated in the TSPA-SR and will do
so for each of these post-closure suitability criteria.
On page 13, similarly, disruptive events will be
evaluated as suitability criteria, also. Then, finally, in
Volume II, the results of the total system performance will
be evaluated.
The methodology described and the criteria will be
evaluated -- will be used for a preliminary evaluation of
the suitability of the site. This is done by comparing the
release standards to the TSPA-SR does results both for the
pre-closure and the post-closure requirements.
You've seen page 15 before. The only point here
is that I'm going to briefly describe the technical basis
documents, some of which Russ has already described.
I want to emphasize here that we have assembled
the site recommendation consideration report such that it is
fully traceable to the underlying technical basis documents.
By that, I mean, specifically, that no new information, per
se, is presented in the site recommendation consideration
report. Everything that is presented and summarized in that
report is fully traceable to the technical basis
documentation that you see in the pink and the purple areas
of this pyramid.
Page 16, Russ mentioned the analysis and modeling
reports used to document the analyses and models of
individual FEPS using site characterization data sets. They
cover both the natural and engineered features of the site.
The PMRs then synthesize and integrate groups of
AMRs to describe and model general categories of features
important to post-closure repository performance.
They serve as an intermediate level, the
equivalent of the TSPA-VA technical basis document, in which
the component models for the TSPA were described.
The SDDs are the engineering analyses to document
surface, sub-surface and waste package designs, and then the
TSPA-SR uses abstracted results from AMRs to analyze the
performance of the repository with a focus on a 10,000 year
compliance period, but it presents results for longer time
periods, as well.
Page 17, I think we've been over this. On page
18, I provide the current status of the PMRs, the process
model reports. In fact, they've all been now accepted as
Rev. 0 by DOE. However, further updates and modifications
to the process model reports are underway in the final
column.
There are two main drivers. The first is that we
are -- the M&O is now completing the revisions to AMRs to
incorporate the no backfill design that Russ described and
those final updates are underway now and they will result in
updates to the PMRs between now and December.
And number two, based on internal comments, the FEPS AMRs,
the features, events and processes AMRs, and there is one
for each of the PMRs except the integrated site model, based
on internal comments, those are also being revised and
updated and those results will also be incorporated in the
PMRs that will be available at the time of the release of
the SRCR.
You will also note here, on the right, that full
revisions of two of the PMRs are underway, the UZ PMR and
the engineered barrier system PMR.
We will have, though, at the time of the release
of the SRCR, all of these PMRs in their final form
available.
Page 19, additional technical basis documents.
The preliminary pre-closure safety evaluation is a report
that's been prepared to support our preliminary evaluation
in Volume II of the SRCR. It's an analysis of the
radiological safety for a repository at Yucca Mountain.
The site description is a comprehensive compendium
of site information, including chapters on natural resources
and natural analog studies.
The repository safety strategy, which will soon be
in Revision 4, is a general plan for the identification and
prioritization of the factors important to repository system
performance and it formulates a safety case where DOE will
present the essential aspects of the performance of a
repository system.
On page 20, I just want to make a couple points
here. The first is that the process that we have used to
assemble the TSPA-SR and the SRCR includes a foundation
built on the left side of AMRs and PMRs, some of which, as I
mentioned, are being updated, in the red box, to reflect the
no backfill design and those support the TSPA-SR and the
SRCR.
We'll go through a similar process and we'll do another
update to the TSPA in the spring and we'll go through the
same process again of updating and revising AMRs and then
PMRs to develop a subsequent iteration of the performance
assessment for the license application.
There are a couple of new boxes in here. In light
green, you'll note the FY-00 technical update. This is a
report that the department will also release at the time of
the SRCR. Its intent here is to provide an update on
testing and design work that has occurred subsequent to the
freezing of the inputs for the TSPA-SR to provide all
interested parties the most current information that we can.
And we are currently contemplating another such
document for the time of the SR currently scheduled for July
of '01 to, again, provide as current information as possible
to support these documents.
On the next page, page 21, DOE has developed the
site recommendation consideration report to inform the
public of the technical basis for the consideration of the
repository at Yucca Mountain and to facilitate the public
comments during the SR consideration hearings. It's to
promote the dialogue.
The SR, the site recommendation, that will follow
will provide a comprehensive statement of the basis of any
recommendation that the Secretary will make to the
President. It will include additional information as
required by the Nuclear Waste Policy Act.
It will include the views and comments of the
governor and legislature of any state or the governing body
of any affected Indian tribe, together with the response of
the Secretary to such views.
It will include, on page 22, the preliminary
sufficiency comments from the NRC. Carol will discuss that
a little further in a moment. It will include a final
environmental impact statement, any impact reports submitted
to the department by the State of Nevada, and any other
information that the Secretary considers appropriate.
On page 23, the act does require that the
Secretary hold public hearings in the vicinity of Yucca
Mountain for the purpose of informing the residents of the
area of such consideration and receiving their comments
regarding the possible recommendation.
Current planning calls for these hearings in early
2001. Location and number of the hearings has not yet been
determined.
Finally, here on the schedule chart, I won't go
through each milestone, but I will identify several key
ones. The first star there in late 2000 represents the
release of the SRCR. The vertical red dashed lines and the
horizontal arrow identify the comment period. Our current
planning is for 90 days. And subsequent to that, the gray
star would represent receipt of the NRC sufficiency
comments, Secretarial decision on whether to proceed with
the site recommendation in June, and then DOE will submit
the SR to the President in July of '01, waiting 30 days
after notification to the state of the Secretarial decision,
a minimum of 30 days.
On the bottom are some EIS milestones which
culminate in the submittal of the FEIS to the President at
the same time as the SR and its subparts.
So that's all I had to present this morning. I
could entertain questions now or we could have Carol do her
piece and have questions later. I'll leave that to you.
MR. GARRICK: Let me ask the committee. Are there
any questions?
MR. WYMER: I have one sort of a general
off-the-wall question. This is going to be a large and
comprehensive document with a lot of stuff.
MR. SULLIVAN: About 1,300 pages.
MR. WYMER: Who will review this thing? It seems
that most of the people in the country who are competent to
review it have been involved in the preparation of it.
Do you have any idea how this thing will be
reviewed and where will they find the people to do this?
MR. SULLIVAN: Well, I can't speak to that
specifically. It will be accompanied by an overview, which
is a much slimmer document, similar to the VA overview. We
have targeted the SRCR to a general audience. We have tried
to make develop the document so that it will be
understandable to people who are not expert in individual
disciplines of engineering or science.
MR. WYMER: But you have no feeling on that, and I
don't really know why you should have, but you have no
feeling of who actually will do the review, where they will
get the people from.
MR. SULLIVAN: DOE has received 11,000 comments on
the DEIS. So we expect people will review and comment on
portions or the entire document.
MR. WYMER: So it's just people.
MR. SULLIVAN: Stakeholder organizations and
individuals, interest groups of various kinds.
MR. WYMER: But the President, in quotes, is the
person to actually say this looks like it's the real stuff
and it will work, so let's go ahead.
MR. SULLIVAN: Right. First the Secretary, then
the President.
MR. WYMER: So somebody has to advise him.
MR. SULLIVAN: Right.
MR. WYMER: And it will not be the public.
MR. SULLIVAN: It will be the Secretary.
MR. WYMER: Okay.
MR. SULLIVAN: Taking into account all of the
comments that have been received on the document and the
views of the affected governors and legislatures and the
preliminary sufficiency comments of the NRC.
MR. WYMER: So it's kind of a closed loop here.
Okay.
MR. HORNBERGER: Tim, in your pre-closure
comments, you mentioned that retrievability would be assured
for up to 300 years.
MR. SULLIVAN: Correct.
MR. HORNBERGER: So I take it you're still holding
to, what, a 50 to 300 year possibility for pre-closure.
MR. SULLIVAN: Yes. We identify the period up to
300 years as the period in which the repository potentially
could be monitored and we would have decommissioned the
surface facilities and entered into a monitoring phase.
But we would have retained the -- not the
possibility -- we have retained the capability to retrieve
the waste up to 300 years, meaning we would maintain the
ground support within the repository and if and when needed,
we would commission surface facilities to handle the waste
retrieval.
MR. HORNBERGER: And then your analysis also then
includes the possibility of a tunnel collapse and things
like this and still have the capability to retrieve.
MR. SULLIVAN: Yes. You will see degradation
analyses in the SRCR and in the supporting documents.
MR. GARRICK: Any other comments? Staff?
MR. LARKINS: A quick question. Yesterday, we
heard from a representative of the State of Nevada who
discussed how his views on the importance of the performance
confirmation plan and DOE strategy, and we didn't hear any
mention of it this morning. Is this a part of your -- how
doe the PCP fit into this?
MR. SULLIVAN: We will describe, and I omitted
that, the performance confirmation plan in the SRCR and
there is a plan, a stand-alone report, that will be
available also. So that was an oversight on my part.
MR. GARRICK: Thank you. Thank you very much.
Carol?
MS. HANLON: Perhaps if I just begin my
presentation, and Andy will go ahead and he will adjust it
and you can hold up your hand if you don't hear.
You will notice that we spent a good portion of
this meeting discussing different portions of the key
technical issues, technical exchanges. I think that that's
an aspect that warrants a good deal of emphasis.
I appreciate the presentations that we had
yesterday from the Nuclear Regulatory Commission, Bill
Reamer, John Trapp and Neil Coleman I think did an excellent
job of setting the stage and identifying some of the things
that have gone on to date and discussing for us the path
forward that we've looked at.
I would like to discuss a few of those things from
the Department of Energy's perspective to clear a couple
areas I think that remain perhaps not fully understood, to
help you all with your understanding of our document and
perhaps understand Dr. Wymer's question a bit more on review
and how the reviews are going.
One of the things I'm going to talk about is I'm
going to talk about process for these meetings, what we're
looking for, what we're going to do with upcoming meetings,
and also how we're handling the agreements on items that
have come out of the meetings, the technical exchanges that
we've previously had and will continue to come out, because
there will be agreement items and we're watching those very
closely.
So as Tim and Dr. Dyer have both said, we have a
requirement from the Nuclear Waste Policy Act that we
provide sufficiency comments. We include sufficiency
comments provided to us by the Nuclear Regulatory Commission
as part of our site recommendation and those are in two
important areas, at depth site characterization, waste form
proposal, and I think the words that they are sufficient,
they appear to be sufficient for inclusion in any
application to be submitted.
That's an important concept. That's a
forward-looking concept and it helps us focus on where we're
at with regard to the site recommendation consideration
report, the SR and forward to the LA.
So obviously to the Nuclear Regulatory Commission
staff, a very important portion of their sufficiency review
has been the resolution of their key technical issues,
non-key technical issues, and those have been documented in
the issue resolution status reports.
Our purpose, our goal is that the technical
exchanges will result in a clear understanding of the status
of each of these and where there is not resolution, a path
forward for reaching resolution.
The first general kind of overarching technical
exchange was held April 25 and 26 in Nevada. That had a
dual purpose; first, the purpose of discussing how
sufficiency would be approached and, secondly, to discuss in
full the status, both perceived by the Commission and as
perceived by the department, with the new information that
we had as we were preparing analysis and modeling reports
and we were preparing the process model reports and going
forward to the total system performance assessment, what our
reflection of the status was.
Based on that, we subsequently set up a series of
technical exchanges on specific topics. Now, this is where
a bit of the unclarity, I think, still remains for your
committee and I would like to just take the opportunity to
clarify that a bit.
You will recall the November 24 letter from Dr.
Brokoum to John Greeves and in that letter, we proposed an
approach for providing additional information which would
support the Commission's ability to review our technical
basis documents and make sufficiency comments.
Based on that, we had suggested a series of
meetings, specifically nine meetings, focused on process
model reports. You've heard a good deal this morning on
process model reports, analysis and modeling reports and
other documents, both from Dr. Dyer and from Tim, and it
perhaps is a bit daunting.
Our approach in setting up these meetings was to
discuss the particular category of a process model report,
the analysis and modeling reports that contributed to that,
the impact to the total system performance assessment, and,
of course, very importantly, the contribution to the
specific key technical issue that was addressed by that
process model report.
To make our series of meetings and our technical
exchanges more effective, we adjusted that approach and I
think that may be something that was a bit confusing and
left you all a bit in a lurch on that.
We are now focused specifically on the key
technical issues and that's so that we can very specifically
take that same information, the process model reports, the
AMR reports, the portions of the TSPA, and address it very
specifically to an individual key technical issue.
So on this, you will see the set that you had
previously seen, I think that we did this schedule in late
July and you've seen it since then.
I briefed you, I believe, in July on this. And
that includes our completed unsaturated zone technical
exchange in Berkeley. The igneous activity, also completed,
was held in Las Vegas, and the container life and source
term that were completed last week in Las Vegas.
Two that you're still familiar with are the
structural deformation and seismicity technical exchange
that will be held the week of October 11, actually the 11th
through the 13th, and saturated zone flow, as we mentioned
this morning, will be held in Albuquerque.
We've added an additional day to that. It's
October 31st, November 1st and 2nd. I also might just make
another comment, to make sure that we have ample and
adequate information for full discussion, full vetting of
the issues and full presentations, basically we have three
days for all of these technical exchanges.
In order to facilitate the Commission's ability to
do their sufficiency review and have their comments ready,
as we've asked them, in by the end of May, the Commission
asked us to go forward in setting up the series of meetings
on remaining key technical issues and to try and have those
done by the end of January.
We moved out in February a bit, but I think we're
pretty close. These have not been fully agreed to with the
Commission staff yet, but I have put months down here so
that you can see what remains before us and get an idea not
only of our busy schedule, but consequently, I think, your
busy schedule.
The in-package criticality, which is subissue five
of the container life and source term, will be held October.
It's actually, I think, October 24 to 26, as it is currently
scheduled.
In November, we will have the technical exchange
on thermal effects on flow. December we'll have the
technical exchange on radionuclide transport.
Also, in December, we have identified the
possibility of a briefing on the total system performance
assessment results, since we had previously had the meeting
in June in San Antonio. Now that the TSPA will be coming
out, there is a potential that there will be a briefing on
that, not solidified yet.
In January, we will have two meetings; earlier
January, evolution of near field environment; later January,
the repository design, thermal mechanical effects. And the
last meeting, the 6th through 8th of February, is the total
system performance assessment integration.
So that's our new set and when we have the
formally agreed to list of meetings, we'll make sure that
you get a copy of that.
You've heard quite a lot about the status of these
meetings and I just want to recap for you a bit. The three
meetings we've had are unsaturated zone flow. The number of
subissues with regard to that were five. The sixth one will
be handled, as we've said, at the saturated zone in
Albuquerque. That's on matrix flow in the saturated zone.
From that KTI technical exchange, we have four
issues which were closed -- subissues, excuse me, which were
closed or closed pending and one remains open. That is on
the infiltration and that came up in some of the discussions
yesterday.
There was some information, new information from
the center that was presented during the technical exchange
in Berkeley that our staff had not had the chance to fully
evaluate. So what we have come up with is, regarding that
subissue, a proposal to evaluate that new information and
identify what we do need to include and what would explain
or justify what we may not think is relevant.
So that's the approach that we are going to
present to the saturated zone. If you have any specific
questions, we have Martha Pendleton here, who can talk to
the specifics of the infiltration.
Another issue that came out of that unsaturated
zone flow meeting was the discussion of the importance of
fully understanding the subsystems as you are also
understanding the performance of the entire system.
I think that's had a little bit of confusion here.
The point is not that because of a very strong component in
this case, a long-lived waste package, you're unable to
understand the subsystems. The point is that in order to
understand the full system, we must understand all the
components, we must understand all the portions of the
subsystem, the natural system, the engineered system.
So our particularly strong portions should not
obscure the issue nor should it be a penalizing component,
but we must understand fully all of those. That's what we
are committed to doing.
Bob Andrews, in his discussion of total system
performance assessment, is going to go into a bit more of
exactly how we take those subsystems, full understand them,
as we move forward to an understanding of the total system.
With regard to igneous activity, we had two issues
there. One is closed, one is open. I included our score
card, and so did John. This is actually we're a little
better than that, we're about 90 percent closed on the
subissue for consequences and the reason we're not fully
closed on that is that we have some AMRs that will be
completed late this year, this calendar year, and provided
to the Nuclear Regulatory Commission, addressing the no
backfill issue, and it was believed that to fully be able to
understand the consequences and close that issue, they
needed those AMRs.
We fully agree with them and we're making every
effort to move forward to get those AMRs and they will be in
their hands in January.
Container life and source term, we had six issues,
we've closed five. The issue, subissue we did not close was
not addressed in this particular technical exchange. It's
the issue of criticality and it will be addressed in a few
weeks at the second CLST meeting in October.
It's not in my handout, but one of the things I
did want to mention to you is that as you can see, and I've
tried to create a complete record here, you can move through
a few of these, John, so that you can see what the title is,
what the status is, and what the agreements are.
Now, it's very important, as we make these
agreements, to track them very clearly and make sure that we
get the exact information back to the Commission on
schedule, as we've promised.
An example of that comes again from the
unsaturated zone meeting in Berkeley, where the Commission
staff asked to see a copy of the test plans for Alcove 8.
We committed to providing those within a week.
We did provide them within a week. Neil Coleman
made sure that the review occurred and he's got our comments
back. So those agreements have been handled. We are now in
the process of evaluating those and seeing if there are
modifications that we can make to our test plan to
accommodate the comments we received from the NRC.
To make sure these things are happening, we are
tracking them very closely, both formally and less formally.
I won't say informally. We have a condition identification
reporting and resolution system, which is a formal system
that's in place, and that's a system, it's important for you
to know that that is in place and it will transition as we
go through the period of having a new contractor.
So these agreements on the items regarding the
closed pending will not be lost. They are in a formal
tracking system and they will transition.
Also, on an operating basis, to make sure that we
are staying very much on top of this, we've instituted
weekly or biweekly briefings on the status of items that are
coming out of these and where they remain and where we are
with regard to providing information to the Commission.
So we are watching those very closely. Another
one that's much on our mind is the infiltration issue that's
coming up for the saturated zone.
I think we can probably move forward, leaving you
with these things to review at your leisure. I think we can
move forward to 14.
From our standpoint, the department has spent a
great deal of effort on these. We understand and appreciate
the effort, also, that the Commission staff has dedicated to
these technical exchanges. We feel that they have been
extremely productive.
The three meetings only have resulted in four
subissues changed from open to closed pendings. Four
subissues I've discussed remain open, and two of those
subissues were not addressed in the interactions. They were
the saturated zone and the criticality. So we are moving
forward.
We believe that these technical exchanges have
been extremely effective in establishing either the status
or the path forward to a closure status.
I feel that our teams are working closely and very
well together. There's a good exchange of information and
that's very productive, I think, to working toward providing
the Commission with the information that we believe they
will need. And the management commitment, both by the
department and the Commission staff, has certainly been a
definite asset.
So we're continuing to hold and move forward with
these technical exchanges, supporting the staff's approach.
We were a bit disappointed that we weren't able to year the
Yucca Mountain review plan approach and that the formal
sufficiency approach. We're concerned that we really are
definitely on target and that we're not missing something
that the Commission will need.
So the sooner that we can know those specific
details and know that we are on target, we can move forward
or we can adjust our path as we need to.
So we'd like to confirm the path that we're
currently engaged in and moving forward to both creating
information that will be sufficient for the license
application docketing and, also, the sufficiency comments
that the NRC will provide.
May I answer any questions for you?
MR. GARRICK: Any questions? John, you have a
question?
MR. LARKINS: I was just curious. What happened
to the biosphere PMR technical exchange?
MS. HANLON: That was included in the igneous
exchange, John. That was very much a part of the second day
of the igneous activities exchange.
MR. LARKINS: Has that been combined now?
MS. HANLON: It's been completed. It was the
second one that was completed.
I believe John Trapp, Dr. Trapp spoke about it
yesterday. It was believed that in order to fully
understand those components of the igneous activity, the
dose consequences and so forth, that the biosphere aspects
had to be brought in.
So I think we had either a half-day or a full day.
MR. LARKINS: Because there was a previously
scheduled separate technical exchange and we had committed
to have somebody participate, but I didn't realize it had
been combined with the igneous activity.
MS. HANLON: Dr. Hines was there, so you did have
support there. And I hope that in this I've been able to
partially explain Dr. Wymer's question about who and how is
this review going to be done.
There is a great volume of information and Dr.
Dyer spoke about it a bit in our hyperlink text system on
the internet.
So if you have a specific question, hopefully
we'll be able to click on that and go down through that.
But these meetings are -- we are attempting to set them up
so that we are explaining the technical basis that's
supporting various aspects of our TSPA, of the site
recommendation consideration report, and specifically
focusing them on the KTIs.
So hopefully that's assisting the review somewhat.
MR. WYMER: Well, I had naively assumed that there
would be some sort of independent initial review, but that
isn't going to happen.
MR. GARRICK: I guess just to extend that thought
a little bit, the committee was quite impressed with the
reports that were prepared by the peer review group that was
put together by DOE on the TSPA and I just wondered if that
particular model was going to be applied to any of these
other key reports.
MS. HANLON: I don't think we've implemented at
this time, but we certainly can keep that in mind.
MR. GARRICK: George, you had a question.
MR. HORNBERGER: Carol, these technical exchanges,
and now that you have some experience with them, obviously
take an awful lot of effort, involve an awful lot of work.
I gather, however, even given your experience, you're
confident that the very ambitious schedule you have you're
going to hold to.
That is, you haven't fallen behind in any of this
as a result of having the ones that you've had.
MS. HANLON: We're doing pretty well so far and
you are right, Dr. Hornberger, it takes a tremendous amount
of effort, both on the part of the Commission staff and the
center and the part of DOE and our supporters.
So they are extraordinarily intensive. However,
we've done pretty well in staying on target. We've looked
at things carefully. The Commission has been extremely good
if something needs to be moved and we've also tried to
accommodate needs that they may have had to move a meeting.
But we're shooting for this target and I'm very
optimistic about it. We did leave ourselves Christmas and
New Year and we managed to leave ourselves Thanksgiving.
If there are no other questions.
MR. GARRICK: Any other questions? I want to
thank you for presenting an excellent scorecard for a very
complex process. That's very helpful.
MS. HANLON: You're certainly welcome. Thank you.
MR. GARRICK: Okay. I think that in spite of the
fact that a break is not noted in the program and if this
goes into the Federal Register, I'm going to accept the risk
of violating that piece of information, and declare a
15-minute break.
[Recess.]
MR. GARRICK: Let's come to order. We're not
going to turn our attention to the often referred to total
system performance assessment site recommendation.
I think, Abe, you're going to lead this off, is
that correct?
MR. VAN LUIK: Last week, I had a reminder that as
we become more effective in life, we take on more risk. My
oldest grandchild got his driver's license last week and my
youngest grandchild decided she could have a better life
without diapers, and I'm happy to report that in the ensuing
five days for both of them, neither one has had an accident.
I'm Abe Van Luik. I'm the Senior Policy Advisor
for Performance Assessment and I'm going to give you a short
introduction to the TSPA-SR, and Bob will give you the
details under the heavy lifting.
I wanted to talk a little bit about the regulatory
requirements that we're addressing right at this moment, the
objectives of the TSPA, summary of the major improvements
since the viability assessment, mention a little bit about
the barrier design and the basis for process models.
If you look at the regulatory requirements, you
know that we have proposed regulations on the street right
now, and to make this talk very short, what we are doing is
addressing all of the nuances of the proposed regulations
from EPA, NRC and DOE.
When these are finalized, they will become simpler
because the NRC will incorporate the final provisions of the
EPA and we will not have basically dual nuances on
definitions of our MEIs and that kind of thing.
If we look at the individual protection or dose,
which is the primary performance measure that we are
concerned with, we have to include probable behavior, as
well as potentially disruptive events.
If we look at the objectives, they have changed
over the years. TSPA-91, for example, was just to show that
we could do one. In '93, we began to get serious about
using TSPA to align the project, to look at what's important
and what's not.
TSPA-95 and the viability assessment got stronger
in that department and then TSPA-SR is to support the
national decision-making process.
TSPA integrates underlying models of individual
process components. We're looking at several performance
measures, individual dose, ground water protection, the
human intrusion standard, and peak dose for the final
environmental impact statement.
We are looking at the significance of the
uncertainty in the process models and Bob will talk a little
bit about some of that evaluation process.
Major improvements. We've had both technical and
process improvements. The process improvements, I think,
are easily underestimated in terms of the effort that they
have taken. But everything is under quality assurance
procedures at this point.
We are using the analysis and model reports that
Russ Dyer talked about as the thing from which we trace our
data and the information flow.
We have explicit evaluation, a comprehensive
evaluation of features, events and processes. We are using
traceable data sets and the TSPA model itself can be used to
move down into the data sets themselves, and we are tracking
the quality status of all data, models and software.
Technical improvements. Some of you mentioned a
while ago, I think it was John mentioned that we did have a
review on the viability assessment.
That review, of course, came after the completion
of the viability assessment. So the TSPA-SR and the TSPA-LA
will be where we respond to that review in terms of
improving our modeling.
Models with major enhancements, looking at those
comments, and also comments from others, such as the NRC, in
the exchanges, as you've heard Carol talk about, of course,
we have learned a lot from the NRC about what their
expectations are and some of these improvements also address
those.
But climate and seepage has been greatly improved.
A couple thermal processes are lot farther along than they
were in the VA.
Waste package degradation, we're looking at stress
corrosion cracking and initial defects in the welds.
Saturated zone transfer and volcanism, all of these models
have seen major enhancements since VA.
The engineered barrier. TSPA-SR is based on the
site recommendation design, no longer the VA design. We're
looking at an average thermal load of 62 metric tons of
heavy metal per acre, which is lower than the viability
assessment. We're looking at at least 50 years of
ventilation, it may be more. This is some of the
operational mode adjustments that Russ was talking about.
We're looking at blending of fuel at the surface
to levelize the thermal load.
The engineered barrier design considers the
titanium drip shield, non backfill, waste packages placed
end to end, an average line load of 1.4 kilowatts per meter.
The waste package itself, still 21 pressurized
water reactor assemblies or 44 BWR assemblies, and
co-disposal of Defense spent nuclear fuel and Defense high
level waste.
The outer layers, alloy-22, 20 millimeters of it;
the inner layer, stainless steel, 100 millimeters. The
inner layer of stainless steel is not taken credit for in
the TSPA. It is a member that gives structural support to
the waste package.
There is a dual alloy-22 lid closure weld. The
outer lid closure weld, the stress is mitigated by solution
annealing. The inner lid closure weld, the stress is
mitigated by laser peening. These turn out to be very
important to long-term performance.
This is just a listing of the process model
categories and the process model report. On the right are
ones that were mentioned by Russ in his talk and, of course,
some of these reports, like the near-field environment and
the EBS degradation flow and transport reports come into one
basket when it comes to the actual modeling, which is the
engineered barrier system environment.
I don't think I need to spend any time on this.
It's just I may make the boast that this is the best
integrated performance assessment we have ever done.
In the past, you could find principal
investigators that said, well, I handed the data over to PA,
but I don't know what they did with it.
This is no longer the case. The principal
investigators are intimately involved in taking their data,
abstracting it and putting it into the total system
performance assessment.
So we've come a long way since the '93-'95 days.
An issue that we have to be aware of is that we
have to have some statement of how confident we are in
whether or not these results that we come up with are useful
in the decision-making process. Demonstrating confidence
requires a lot of things, but it requires showing a
sufficient understanding of processes, determining system
behavior.
Carol mentioned this in her talk just a few
minutes ago, that the NRC staff is very concerned that we
show that we understand the processes that we're putting
into our modeling.
Systematic applications of the features, events
and processes, screening. It's a way to show completeness
of the arguments, that there's not something big out there
that you've just completely forgotten about. This is
another way of showing that you have a reason to have
confidence.
Systematic evaluation of component process models
and their importance. You can have a haphazard evaluation
and do some neat calculations that say, oh, look how
important this is, but a systematic evaluation is what's
important to building confidence.
And you have to show that you have properly
incorporated the important uncertainties. And, of course,
the TSPA, as your documentation, has the challenge to make
these points clearly and traceably, and in my review of that
document, I find that it's a very good read. It's a good
document and it's well on its way to illustrating these
points quite nicely.
Happily, the NRC staff and we see things the same
way when it comes to a risk-informed performance-based
approach, and I think some of the success that Carol was
talking about in having issues closed pending, the delivery
of the final products so they can verify that we actually
did what we said we're doing.
Some of that is based on them and us agreeing that
some things are more important than others. Risk-informed
means that the entire uncertainty distribution, not just
mean value lines, are being used to inform.
Performance-based means that the outcome is -- you know,
whether a feature or a system or a process is important to
swinging the outcome one way or the other, is an important
criteria for judging performance.
And, of course, something that -- as a corollary
to that is something that we mentioned on the previous page.
You also have to show that you understand what you're
talking about, because if you don't understand it and model
it wrong, then your conclusions here don't mean much.
So all of these things are together to give us
confidence.
We use these types of considerations to prioritize
science, engineering, design and modeling, and if the budget
comes in lower than we would like it to, we will invoke
these types of results to say, well, this is more important
than that and adjust the funding for science and engineering
accordingly.
And we also use these considerations to rank key
technical issues and decide on the level of effort to be
devoted to address them and I think on this, we are in synch
with the NRC staff. They agree that this is the right thing
to do.
The thing that we have to do is to make decisions,
even in the modeling of this system, in the face of
uncertainty. The basic rules that we have applied so far is
that where something is extremely complex or the quantity of
data is just insufficient to develop a meaningful
distribution, that we take a conservative or a bounding
approach.
We have several coordinated activities underway
now to evaluate how these decisions, which were made as part
of the process of creating the TSPA-SR, affects the actual
performance measure of dose.
We are looking at unquantified uncertainties and
these are the conservative values I talked about in the
first bullet or, in some cases, maybe even optimistic
values. This is in the eye of the beholder or the reviewer,
in some cases.
We are identifying those and then we will do a
trial study, coming up with a distribution for that
parameter and running sensitivity studies to see how
important it was to have assumed that, or should we go to a
more detailed approach.
On the next page, we are also, at the same time,
looking at the quantified uncertainties, the ones that are
documented with data distributions, CDFs, et cetera, which
are sampled into TSPA. And we're looking at the
uncertainties that were considered at each modeling level
and to get a better feeling for just how uncertainty has
been rolled up, how well or how poorly it has been rolled
up, all the way from the data interpretation process level
modeling into the TSPA.
And depending on the outcome of these activities,
a given activity may be expanded or a new activity defined.
This is work in progress, in other words.
The goal is to increase understanding of the basis
for the TSPA results and improve the basis for judging if
there is an appropriate level of confidence for the current
stage of the societal decision-making process.
The current status of TSPA-SR analyses, and some
of you may not believe this, but some of the results
presented today are preliminary and subject to change. We
are still in checking and this got a chuckle at the
technical review board meeting from some people saying,
yeah, sure, you're just saying that.
But you will see in what Bob presents that some of
the curves have changed since the TRB because of the
checking process. This is serious. You are seeing draft
material that is still being worked.
And so they are certainly not suitable at this
time for making regulatory compliance judgments. They are
intended to be used right here, right now, for general
discussions of sensitivities.
The calculations that you're seeing are going into
Revision 00 of the technical report. The repository safety
strategy Revision 04, which is also in draft right now, and
the SRCR. We expect to make minor updates, not major
revampings, of all of these calculations for TSPA-SR
Revision 01, which is coming in next spring, which will
support the site recommendation and the final environmental
impact statement.
So you're seeing a work that's close to being done
for one stage and then there will be another smaller stage
for the SR, and then we have not looked in this presentation
to the LA.
And, of course, you'll want to save your questions
for Bob Andrews, who is now going to show you the technical
side of things.
MR. GARRICK: Committee? Milt, go ahead.
MR. LEVENSON: I've got a couple of questions.
One has to do with I suppose you could define it as a
decision-making process. As you go through here, items are
either included or you decided to leave them out, like not
taking any credit for the stainless steel canister, et
cetera.
Whether it's to include something or to leave it
out, at what level, who makes those decisions? How much
review is done of whether you should include something in
the TSPA or not include it?
This has nothing to do with the technical part of
how you treat it, but who decides, in essence, the scope?
MR. VAN LUIK: That's a good question. I think
there is a process that's not as well defined as you might
think it is, but it's in the process model TSPA abstraction
interactions where it's actually decided that there's enough
information to go forward with this, to bound this, or to
say, for the sake of conservatism, we will not take credit
for this, although it has a definite purpose, which is to
maintain the integrity of the waste package.
So these types of decisions are documented in the
AMRs that describe the abstraction process, for example, and
in some cases, they are documented in the analysis and model
reports for the particular example you're talking about, for
the waste package lifetime, where it was discussed that,
yes, you can get credit for hundreds, maybe even thousands
of years, but because of the way that the system is
functioning now, this does not really add much except in the
terms of the doses of two, 300,000 years out, when it would
not perturb things at all.
So it's all documented, but the decisions were
made, in some cases, at a lower level, at some cases at the
abstraction level, and in some cases, DOE might walk in and
say do this differently.
So it's a decision process we're all made aware
of, but it happens at different levels, but hopefully it's
our intent that all of these decisions are documented in the
AMRs and then rolled up into the PMRs.
MR. LEVENSON: They may be documented, but are
they carried forward in evaluations such as uncertainties,
because it seems to me they could have a significant impact,
particularly things that are left out.
MR. VAN LUIK: The task that I'm very well aware
of, because I'm part of the DOE oversight of it, on the
uncertainty evaluations that I was describing, these are
some of the issues that we're looking at; should we have
done what we did or should we bite the bullet and go into
more detail in the modeling of this particular issue.
So it's definitely one that we will address in
that process, but that's still work in progress.
MR. LEVENSON: In the consideration of
uncertainties, are they all treated equal? I mean, some
uncertainties are symmetrical or something is plus or minus.
In other cases, uncertainty is all plus or all minus.
In looking at the overall uncertainties, are
things being carried with a sign as well as a quantity?
MR. VAN LUIK: This is actually the topic being
addressed by our uncertainty task, because what we did at
the beginning is we put out some general guidelines on how
to treat uncertainties. What we're doing now is verifying
whether those were followed or not and we're finding, in
some cases, that what you're describing is basically a
judgment on what the degree and sign of the uncertainty is,
that it was not done. So we're going back to fix those
types of things.
But in every case, the analysts thought that they
were making a conservative assumption, except in one or two
cases. Some other analysts disagreed with them.
So we are getting at the bottom of those types of
things. But I think this should not be confused with the
idea that we did not capture what we know are the major
causes of uncertainty and I think those are very well
wrapped up in this TSPA.
So we're looking at something that's a second
order correction, basically.
MR. LEVENSON: One other question, and I'm not
sure you're the appropriate one to ask, but you're standing
there. One of the very, very useful outputs of the work
you're doing here, but I'm not sure it's being done, and
that is the design has been evolving over the last, say,
couple of years, a fair amount of time and money has been
spent on the design evolution.
The TSPA could tell you, probably better than
almost any other method, how effective those design
improvements have been or are they improvements, do they
really reduce dose to the public at the end.
Do you have any feel for how much change in the
dose to the public has occurred because of so-called design
improvements?
MR. VAN LUIK: We have done considerable work in
sensitivity analyses, a few of which Bob will show in a few
minutes, after I sit down. But the basic point is my answer
would be yes, we have a very intimate relationship with the
designers and we evaluate what they do in those terms.
However, there's other things besides dose. There
is defense-in-depth considerations. There's considerations
of confidence. So because there is uncertainty in the
modeling, we also do things like add a drip shield that the
TSPA shows that for 10,000 years, since the waste package is
intact with or without a drip shield, the dose comes out
about the same. It's not exactly the same.
But there is another consideration. Do you have
defense-in-depth? Do you have reliance on only one barrier?
That drip shield gives us two barriers. When you take away
one or the other, as you will see when the repository safety
strategy four is issued and also you will see in TSPA-SR
documentation, you will get the feel that there is actually
some backup in this system and that you can have confidence
that even though have uncertainty here, that 10,000 year
dose number is a pretty good number.
MR. GARRICK: Ray?
MR. WYMER: No.
MR. GARRICK: George?
MR. HORNBERGER: Again, just a quick follow-up on
Milt's question. Have you done a catalog? We're talking
about these bounding values or conservative values or on-off
switches. Do you have a catalog? Can you give us an idea
of how many of them you have to deal with? Is it ten, is it
100, is it 1,000?
MR. VAN LUIK: I think it's over 100. We have an
initial catalog, but this is work in progress. And so it
may expand and it may decrease when we see that we have
double-counted some items.
MR. GARRICK: Abe, this is a process question and
it is an extension of Milt's question. It's one I will lay
out that we may come back to with the other presenters. But
I want to get it out on the table.
We're seeing a lot of language now about
quantifiable and non-quantifiable uncertainties. It's
language that's also popped up on the nuclear power plant
risk assessment world.
And I think that it's a situation where there is a
great deal of opportunity, it seems to me, for a lot of
mischief and I'd like to be enlightened a little bit more on
the whole issue of non-quantifiable uncertainties.
You say that the way you're handling these, for
the most part, is to take point estimates and take and use
conservative values or bounding values or whatever, and, of
course, part of Milt's question and George's question is
some sort of a taxonomy of the impact of these
non-quantifiable uncertainties and how they, in the
aggregate and through the propagation process, impact the
overall credibility of the analysis.
But the whole concept bothers me a little bit,
because it's a little bit contrary to the notion of what we
mean by quantitative risk assessment. Not that you can
quantify things that you can't quantify, but the whole
thrust of doing a risk assessment is not the manipulation of
statistics and information nearly so much as it is
establishing the logic between what you're trying to
calculate, which might be an event frequency, about which
you may have no information, the logic between that and a
level at which you do have information.
Then the thrust of the evaluation, the review is
on the credibility of that logic, not so much the
credibility of an unquantifiable piece of information.
So I'm just wondering, the way we got around this
a lot in the nuclear power risk models was to spend a great
deal of time establishing that logic and that, in essence,
became the focus of the creativeness, if you would, of the
risk assessment as opposed to what often comes up on
people's minds when they think of a risk assessment as being
a game of statistics.
I've said many times, statistics may be five
percent of a risk assessment, but it's not a very big part
of it. The real effort is in establishing the answer to the
question what can go wrong and what characterizes the logic
of things going wrong.
Are you doing anything specifically to get to these
non-quantifiable contributions to uncertainty of that
nature? Are you really -- to me, that's what the
breakthrough of risk assessment was all about.
The rest of it is old technology, came about by
way of reliability analysis and general modeling. What's
really creative and the aspect of risk assessment that
constitutes a major step forward is this modeling process or
this logic development process that you go through in going
from what you want to learn about, about which you have
nothing, down to something that you have good information on
and you clearly understand the connection between that and
what you're interested in.
Isn't that the way to address non-quantifiable
uncertainties and are you doing that? You don't have to
answer that completely now.
MR. VAN LUIK: I can give you a partial answer.
We're very well aware of this issue and that's why I
mentioned we have a long list of candidates. What we want
to do is with some outside expert help, pick out the most
likely importance items, perhaps half a dozen to start with
out of that list, and say, well, if we have that uncertainty
quantified in stead of bounded at this point, what would
that buy us.
And what we'll do is for that six or maybe eight
items, we are talking about invoking an expert elicitation
process, with people who would have a feel for this subject
from the outside, as well as one or two from the inside and
establishing a PDF for that particular parameter or modeling
option, and then looking at the importance to the outcome
from that and then depending on -- and that's why I said,
you know, depending on the outcome of that, if that shows,
whoa, this is a bigger thing that we originally thought it
was, then we'll move on to the next five or six and by the
time of licensing, we should have a much more solid story.
But this is something that will take time and it's
a sizeable investment. We're aware of the issue and this is
the approach that we're piecemeal putting into place for
dealing with the issue.
MR. GARRICK: Thank you. Any other comments?
Yes, Milt.
MR. LEVENSON: I have sort of a follow-on question
to George's about this catalog of things left out and are
bounding.
Is it possible to get a copy of that list,
recognizing that it's much more fragile and work in
progress, but just to get a -- at the moment, I find that I
have no real feel for the scope of this issue and it's a
fairly important part of the credibility of the TSPA.
MR. VAN LUIK: The TSPA-SR document itself, when
it comes out, will have a list in it of places where we use
conservative assumptions and that's the starting list and
that's a pretty short list.
In the meantime, some of our other people have dug
way into the hinterlands of the process models and the data
interpretation reports and come up with a much longer list.
The principal investigators looking at these
things feel that that's -- the one approach may be a little
bit short, the other approach is a little bit overboard.
But you will see the very first version when the
TSPA-SR document comes through the DOE review and becomes
available to you.
MR. LEVENSON: That will include lists of all of
the things left out, like the stainless steel in the
container, et cetera.
MR. VAN LUIK: Those kinds of things are the more
obvious ones and they will be discussed in the document,
yes. But I'm talking about where we use the bounding value
rather than a PDF, because our internal expert judgment was
that to go beyond that, since we already know that it makes
very little difference to the performance measure of
interest, would be money not well spent.
So those kinds of analyses also will be reflected
in that table in the TSPA-SR, and then you go to the AMRs
and PMRs and see what the actual logic was.
So that is pretty well in there. It's pulling all
that together and we have several different people doing it,
coming up with different lists, and our job, our task
force's job is to come up with one list that we all agree
on.
But as soon as it's a little bit less flaky than
it is now, you can have it.
MR. GARRICK: Okay. Andy?
MR. CAMPBELL: It sounds like what you're focusing
on, though, are parameters, where you're not sure what the
range ought to be, so the analyst picks a value that they
believe bounds what that range of values would be.
And in that analysis that you're doing, are you
going to also look at what the shape of the distribution
might be on the results in terms of that parameter? That's
one question.
But more importantly, how are you going to factor
conceptual model uncertainty, because you're dealing with
parameter uncertainty in that case, but you also have the
whole issue of do you have the right conceptual model and
then you get into type one and type two type of errors, and
that kind of stuff.
Do you have a plan for dealing with that?
MR. VAN LUIK: That is included in what we are
supposed to be looking at. Obviously, the easiest thing to
do is to look at parameters. That is another order of
magnitude more difficult, but that goes to the
interpretation of data, what interpretations does it allow.
So it definitely is part of the plan, but whether
we get that done in the first phase or the second phase, I
would guess it would be the next phase.
But we plan to do this to the point that at the
time of licensee application, we have our ducks pretty well
in a row. But I have to re-emphasize that I think and I
think most of the PIs in the program think that these are
second order corrections and we have captured the major
uncertainties and in several instances we have captured, by
analyzing, different conceptual models, for example, and
chosen either the more conservative one, which is another
source of conservatism, or we have somehow combined them.
So there is already conceptual model uncertainty
addressed in the TSPA-SR, and the supporting documents,
itself.
It's not like it's something that we say, oh, gee,
we forgot that, but there are the major ones, like in the
unsaturated zone, and then there may be some other minor
ones, too, that we will want to address further in this
exercise.
MR. GARRICK: Okay. No further questions, we'll
listen to Bob Andrews.
MR. ANDREWS: Thank you very much. As Abe said,
this is work in progress. The documentation of the analyses
and calculations and the model and the report itself are
internal to the M&O review and comment resolution as we
speak.
It's been an incredible team. Most of you are
aware of them from the VA. It's been a fairly stable team,
I'm very thankful for, and that team is very hard at work
still, that team in Albuquerque and here in Las Vegas.
I had the joy yesterday of looking at the cover
page of the technical report and in the cover page, we're
putting all the contributors to the documentation of the
TSPA-SR and it was just kind of -- by the time you looked
through the 20 or 30 names on there, you were well aware of
the hard work and incredible work of pulling this thing
together and documented, as Abe said, in as clear and
concise and traceable and transparent a fashion.
And sometimes, some of those adjectives compete
with each other, as though of you who have prepared large
documents are aware. You try to make it traceable, but in
so doing, you might have lost some transparency, or you've
tried to make it transparent, but in so doing, you might
have lost some traceabilty.
But I think we have a happy medium between those
and the issues that were raised by the questioners in Abe's
presentation I think have been addressed.
My objective today is to kind of walk through the
TSPA-SR as it stands right now. The various attributes,
look through the system, how the system is connected or the
components of the system are connected, and then go to the
results.
The objective in the hour or hour and a half that
we have here is not to go through each individual component
part, starting with climate and going through to biosphere
and to disruptive events, but to talk about it as an
integrated system.
If you have questions about an individual part,
I'll do my best about how that part was implemented in the
TSPA model. As Abe and Russ and Tim and Carol told you, the
whole building blocks of this TSPA are those 121 AMRs that
provide the technical foundation and the data, in fact, that
support those AMRs. Those AMRs, those analyses, model
reports have used site-specific data, analog data, as
appropriate, in situ data, laboratory data, literature data
to develop their technical bases and the technical bases
reside in those AMRs.
So with that, let me go on, John, to the next
slide and talk about process.
The next two slides kind of go hand in hand. I
think this is a fairly well defined process. This is a
pictorial representation essentially of the requirements of
TSPA as they are defined in Part 63, where the first step is
to identify those features, events and processes that may
significantly affect the performance of the repository
system, both the engineered features, events and processes
and the natural system features, events and processes.
We've looked through, starting with an NEA
database, which the department and NRC were both a part to
in the development of that NEA database, as well as the
international community at large.
WE added Yucca Mountain specific features, events
and processes to that, to the point where it became
something like 1,600 features, events and processes that
then had to be either evaluated and screened into a model
or, with a basis, screened out of the model.
Once we've done that and I think the NRC is
reviewing the analysis and model reports that relate to the
FEPS screening process, we developed two basic scenario
classes using the definition in the TSPA-I IRSR of scenario
class.
Those scenario classes are what we call a nominal
scenario class and, in this particular case, of a panic or
disruptive events scenario class.
IN the disruptive event or volcanic scenario
class, there are actually two. I think the parlance in the
TSPA-I IRSR is an event class; two event classes, one an
intrusive event class and one an extrusive event class.
Given that I have those scenario classes, now I
have to have the individual component models and the
integration of those individual component models and the
scientific technical underpinning for those individual
component models.
In the TSPA, if you come around the wheel of the
figure, there are essentially nine of those component parts.
There's subcomponents, that I'll get to in a second, that
are in a series of backup slides to this presentation, but
we start first with the unsaturated zone flow, the things
above the repository, climates, air infiltration, et cetera.
We then get to the engineered barrier system
environments. The environments in the drift, around the
drift, in the rock, that can affect the degradation
characteristics of the engineered materials that are placed
inside the drift, with the proposed design that Abe talked
to you and Russ talked to you about.
We then get to the degradation of package and drip
shield, their performance over time. Next, the waste form.
Once the packages are degraded, the waste form starts
degrading, the cladding can start degrading, the internals
of the package affected by the environments inside the
package once they start degrading.
We then have transport through the package,
through the invert materials, into the rock, and then
transported in the unsaturated zone to the water table,
transport through the saturated zone, and, finally, we have
a biosphere, where the nuclides that are released to the
community of individuals -- let's not get involved whether
it's a group or maximally exposed, but we'll talk about that
a little later -- that group of individuals is exposed to
those nuclides.
So we end up with a volcanic dose, dose induced by
the low probability volcanic scenario classes, and the
nominal dose, those that are not impacted by these low
probability volcanic scenario classes.
As Abe pointed out, there's two other principal
performance measures, regulated performance measures, the
ground water protection, concentration, however that's
finally implemented in Part 63, assuming that it still
exists in 197. It does exist in the proposed 197. And the
human intrusion dose, assuming, again, that it's implemented
in the way Part 63 has it currently in the draft.
As you're well aware, Part 197, in its proposed
regulation, allows the applicant to potentially exclude that
scenario from consideration if the applicant so decides.
We have, for the purposes of the TSPA-SR, included
that particular scenario class into the assessment. It's
not weighted. It's a stylized calculation to evaluate the
robustness of the system.
The one that's not shown on there is the peak
dose, the requirement for the final environmental impact
statement.
So that is the process of developing the TSPA-SR.
If I skip over the word slide, because that's in there more
for completeness, and walk now through the various component
parts that feed into the TSPA-SR.
This set of attributes is very familiar to this
board, I know, from the repository safety strategy Rev. 3
and also the viability assessment. The viability assessment
volumes three and four talk about the major attributes that
affect the long-term performance of a repository at Yucca
Mountain.
All we're trying to do here is trying to put it
into a little more general construct and use some icons to
point the reader through where they are in the system,
starting with the natural system, with the water above the
repository, as it gets into the drifts, then the package
itself, then the mobilization and release; finally,
transport and whatever the consequences and risks associated
with disruptive events might be.
As a general view, the next slide takes the TSPA
wheel for the nominal scenario, a similar one for disruptive
scenarios, but this is for the nominal, and shows you the
individual component parts and the individual process model
factors or subcomponent parts or process models, whatever
you want to call it, that feed into that TSPA-SR.
This is kind of shorthand notation. In the last,
I think, nine slides of your handouts, they're in the
backup, I didn't feel it was necessary to go through it in
the presentation, but I think it's to provide you a road
map, if you will, from the feeds into TSPA, which are shown
here and the individual component parts that are shown
there, to show you what analysis model report is the final
analysis model report providing the input parameters, the
input parameter distributions, discussion of alternative
conceptual models, discuss the technical bases for those
parameters, what those ones are.
So it's a tabular mapping that takes the
individual parts, piece parts shown on this wheel, tells you
what parameters those piece parts are generating. There's
on the order of several hundred parameters that are being
generated for input into the TSPA, and shows you where the
supporting documentation is for that.
It gives you the analysis model report title, the
analysis model report number.
So I believe the Commission has, I think, as Russ
said, 119 of those. So I believe all the ones that are
indicated there, the Commission has.
That's more of a traceability completeness kind of
backup presentation than for you to necessarily do anything
about, unless you want to review those AMRs.
So the next set of slides just walk through those
process model factors, the individual component parts that
feed into the TSPA model, starting, first, with those that
affect the attribute. That's the water contacting the waste
package. So climate, infiltration, UZ flow, the effects of
thermal hydrology on the in-rock processes and, finally,
seepage into the drifts.
The next slide shows those principal factors that
are affecting the environment inside the drift, the
environment that the engineered barriers are likely to see
as they change with time after the wastes are emplaced. In
particular, the chemical environment and the thermal
hydrologic environment.
Also in that physical environment are the stress
environments associated with the degradation of the drifts
themselves.
The next slide looks further into the drifts and
this is essentially looking at those component parts that
relate to the degradation characteristics of the drip shield
and the degradation characteristics and projected
performance of the waste packages themselves.
Next slide gets into the internals of the package.
We have two basic types of packages, one being the
commercial spent nuclear fuel packages and one are what have
been termed the co-disposed packages. It's co-disposed
glass, logs with DOE spent nuclear fuel rods going down the
center.
In addition to these, though, there are other
kinds of packages, special packages, for example, the Naval
wastes have specialized packages because of their size and
handling requirements.
But these are the two principal ones and any other
special type package, we've done a special off-line analysis
of the consequences associated with that kind of inventory
and that kind of waste, if it's different from these kinds
of wastes.
The next slide, it should be pointed out that
there are on the order, for DOE type wastes, there are on
the order of several hundred different specific waste forms.
There are not data on every one of those specific waste
forms, so the DOE spent nuclear fuel program, for our
purposes, has lumped those waste forms into 13 individual
types of waste forms, with similar types of characteristics
and similar types of inventories and similar expectations
about the degradation of the cladding associated with those
waste forms.
The next slide talks to the transport aspects,
away from the engineered barriers. In particular, transport
through the unsaturated zone, transport then through the
saturated zone, and ultimately the uptake of these
contaminants by the biosphere group and whatever dose
consequences are associated with the uptake and use of the
water that may have been contaminated at some point in time
by the other degradation processes and transport
mobilization processes.
The next slide shows that when we have a volcanic
event, with the probabilities that are currently being
estimated, and I believe you talked about those yesterday,
when you talked about the KTI meeting on igneous activity.
Right now, we're sampling that probability from the expert
elicitation that was performed on the probability of an
igneous event, but we have then two types of consequences.
So, therefore, two types of event scenarios that
are being assessed. Type one is the event occurs,
intersects the repository, degrades the package and the
event conduit continues to the surface and you have a cinder
cone and an ash associated with that. The ash is
redeposited with the wind over the member or members of the
critical group and there's a dose associated, potential dose
associated with that release pathway.
That one we've called an extrusive volcanic event
or an eruptive volcanic event scenario event class.
The other possibility is that the dike intersects
the repository, degrades the packages sufficiently so
they've lost their containment possibility, degraded the
drip shields, degraded the cladding, and then the normal
processes of the nominal scenario take place; i.e., all the
slides that I had in there earlier about radionuclide
mobilization, alteration of the waste form, release from the
waste form, transport through the engineered barrier system,
transport through the UZ and transport through the saturated
zone, and then uptake in the well and biosphere dose
consequences associated with that.
So we have two very different pathways, all with
the same initiating probability, but very different
consequence models from that initiating probability on.
They are then, of course, combined at the end for the same
event.
If I go to the next slide, the regulation
currently requires stylized human intrusion scenario. This
is that stylized human intrusion scenario. Somebody drills
inadvertently, goes through a package, goes through the
waste form, goes back through the package, back through the
EBS and down, continues down to the saturated zone, and then
radionuclides can be mobilized, released from the package
through that degraded -- what now is a degraded engineered
barrier, through what now is a degraded unsaturated zone
barrier, and through into the saturated zone and then the
other processes take their normal course.
The next slide tries to summarize, I think, what
Russ has told you, what Abe has told you, and I'm going to
go into a little more detail on some of the following ones
on.
The technical bases -- turn back to the viability
assessment. The viability assessment, volume three of the
viability assessment, which I know this panel reviewed, had
a large technical basis document that went along with it,
essentially nine chapters. That provided the individual
bases for the individual component models in the viability
assessment.
In the SR or the SRCR TSPA that we're talking
about here, that nine got expanded to nine process model
reports, which are very similar, slight differences between
the technical basis document and how they've lumped the
process model reports.
But the fundamental science is embodied in those
121 AMRs, analysis model reports, developed by the labs and
the GS and M&O participants to support the TSPA-SR.
Of those 121, 40 of them are direct feeds into the
TSPA. So those 40 provide a direct data set or model or
conceptual model or equation or something, are a direct feed
into the TSPA.
You say, well, what about the other 80. Well, the
other 80, probably 15 of them relate solely to screening
arguments, features, events and processes screening
arguments. The other 65 are process models. They are
alternative models. They are supporting models that feed
into those 40 that ultimately support the TSPA model itself.
So all 120, we have several family trees of these
120 and how the information flows in all 120 AMRs takes
about 15 figures to show all of that, and we've put that in
the appendix of the TSPA document, to show where did all the
information come from to support the final feed into the
TSPA.
So one can very, very quickly and very easily pull
the chain, pull the string, and go back to the AMR that gave
the technical basis for its inclusion in the TSPA.
And I might add, based on the discussion that was
going on before, the technical bases for the assumptions
involved in those analyses and models and if there were
assumptions on degree of conservatism or degree of
complexity or something that's going to be treated as a PDF
or something that's not going to be treated as a PDF or
something that's not going to be treated as a PDF and the
reasons for that, it's in those supporting analysis model
reports.
The 40 that feed directly into the TSPA-SR model
are shown on this slide. This is the one you need in
addition to Russ' pyramid, the one you need the magnifying
glass for. Actually, the next one, too, you'll need a
magnifying glass for. In the actual document, they appear a
little bit bigger.
But the color coding is color coding the AMRs to
the corresponding process model report in which that
analysis model report is summarized and the arrows are
showing where in the TSPA model are the individual component
analysis model reports input and then where in the middle is
the process of doing the TSPA, starting with the package
degradation, going to waste form degradation, going to EBS
transport, UZ transport, SZ transport, and, finally, the
biosphere.
That middle part is the guts of the TSPA model, if
you will. All of those inputs are what's being integrated
within the context of the TSPA model.
If you don't like boxes, then the next two slides
try to walk it through from an information flow point of
view; what information, what kind of, if you will,
intermediate result is passing from component to component
within the TSPA model.
One of the objectives of the TSPA model itself and how it's
been constructed and how it's been documented is to show, in
as transparent a fashion as possible, given that I have 40
AMRs that are feeding it, as transparent a fashion as
possible, how the information flows from component to
component; how does climate information flow to unsaturated
zone flow; how does unsaturated zone flow information flow
to seepage; how does thermal hydrology information flow to
the degradation of the package, degradation of the cladding,
degradation of the drip shield; how does thermal hydrology
information flow to the characteristics of the invert, the
thermal and hydrologic characteristics of the invert.
So there are placeholders within the TSPA model
where we go in and we've done this in the technical report
and in the model document, where we go in and stop the
results, if you will, and look at what information is
passing from component to component; what flux, it's general
energy kinds of things.
It's heat that's passing from component to
component, it's mass that's passing, it's volume of fluid
that's passing from component to component, and ultimately
it's -- and it's chemistry passing from component to
component, and, ultimately, it's radionuclide activity
that's passing from component to component.
You can say that from barrier to barrier, you can
say it from feature to feature, but it's traceably and
transparently showing how that system evolves based on the
models available through time.
Some of that information, as a backup, I've
included, in the first part of your backup slides, I was not
going to go over it here unless it gets into that level of
detail. But as we go from flow to seepage to package to
water mass movement, mass release, activity release, and
ultimately activity release at the 20 kilometer point of
compliance, that ultimately leads to a dose. That's all in
the backup and it's in greater detail in the technical
report.
So these two slides show that how information
flows from part to part. Same thing on slide 17. It shows
once I get internal to the engineered barriers, that is
internal to the drift, how the environments are propagated
through time and what downstream processes impact, and then
how the degradation characteristics of the engineered
barriers are propagated through time, and then ultimately
the release, mobilization and release of nuclides from those
engineered barriers and back into the natural barriers.
The next slide, Abe alluded to this. Uncertainty
and variability, both primarily quantified, has been
directly incorporated in the TSPA-SR model. The third
bullet there is a bullet that Abe had on his slide and that
is where the individual analysis model report originator,
the reviewers, the checkers, felt there was either a large
degree of complexity, large degree of uncertainty.
The goal was to be defensible and in being
defensible, they were probably, in some cases, a little
conservative. They documented that in their analysis model
report. Are there alternatives they could have chosen?
Yes. Did they document what those alternatives were? Yes.
Did they give a rationale why they didn't choose that
alternative? Yes.
Could we propagate those alternatives back through
the rest of the system in sufficient time? Maybe, because
some of those alternatives require alternative
representations. They require alternative data. They
require alternative analyses and they require alternative
abstractions into the performance assessment.
It's not a simple flick the switch. It is in some
cases. If it's down at a parameter level, I think Andy's
question is very well taken. If it's down to the parameter
level, it is a very simple aspect. If you don't have the
process model for how you think -- take the example that was
alluded to earlier, the stainless steel degrades and that
degradation characteristics are sufficient complex and the
amount of information available in the environments that we
have is sufficiently uncertain, it would have taken a big
effort to incorporate stainless steel into the TSPA model.
First, the process model, then the abstraction,
and finally into the TSPA model. So a conscious decision
was made by all concerned, including the Department of
Energy, in that particular case and others, of which things
to include and which things to exclude and carry those
excludes.
MR. GARRICK: Bob, just to pick up on that a
minute. Obviously, you have to have some evidence in order
to assign a number or a parameter that you think represents
an upper bound or a conservative estimate.
It just seems that it would be easier to hedge
your bets with a discreet probability distribution, for
example, than it would be a single number. In other words,
you talk about an unquantifiable event or number or
parameter, on the one hand. On the other hand, you say you
assume conservative values.
So you've got to have some basis for justifying it
as a conservative value.
MR. ANDREWS: I think they do. I think --
MR. GARRICK: And my point is this. It's easier,
as a matter of fact, to justify some sort of a distribution
than it is a single value.
MR. ANDREWS: You're right. To justify the
distribution, in some cases, say I think I'm pretty sure
it's within this range. I have evidence to say it could be
at low values, pick the parameter, pick the model, it's the
case all across the board.
There's evidence to support it down here. There's
evidence to support it up here. There's evidence to support
it in the middle. It might be analog evidence. It might be
direct field observations, whatever the evidence is.
However, when faced with the requirement of being
as defensible as possible and to not be optimistic with how
performance may evolve in this system over time, the
analysts, I believe, personally, correctly, went with the
conservative approximation.
There have been words in Part 63 or in the
statement of considerations, perhaps, I'm not sure where
they were for Part 63, that if the applicant -- it might
have been 60, in fact, I forget where they were -- if the
applicant has uncertainty in a particular aspect or
alternative representations or alternative models, it is
okay to include those alternative models and alternative
representations in your performance assessment, but we still
want to see the effects of that more deterministic, more
conservative representation.
MR. GARRICK: That's not a particularly
unreasonable approach. My only point is you don't want to
get yourself trapped into saying, on the one hand, that you
have no information, and, on the other hand, you're using a
number that's characteristic of information.
MR. ANDREWS: That's well taken. That's a point
well taken.
The next three viewgraphs summarize some of these
aspects in a kind of Consumer Reports sort of fashion of
what uncertainty was directly incorporated in the TSPA-SR
model, what variability, and this is generally spatial
variability, was included in the TSPA-SR model, and a brief
set of comments.
The comment, if I didn't check uncertainty or
variability, those are generally the ones where a more
conservative representation was taken within the analysis
model reports in order to avoid some of the complexity
associated with that particular process or coupled process.
The very first one on there, on page 19, is the
coupled effects on seepage. This was one that also was
noted in our review of the viability assessment, it's been
noted several times by the Nuclear Waste Technical Review
Board, noted by NRC staffers and center staffers on their
review of the viability assessment, as well.
And that is that the actual seepage into a drift
following emplacement and the perturbations that are caused
by emplacement, the mobilization of water, the changes in
the chemistry, the changes in the mechanical stress around
the drift, the degradation of the drift support system
itself, all of the thermal mechanical hydro chemical coupled
processes are -- I think everybody would acknowledge are
very difficult to quantify with a high degree of
defensibility.
There are data, yes. There are data from the --
specific data, even, associated with seepage tests that have
been conducted by Berkeley in various niches at the site,
the actual thermal hydrologic drift scale test at the site,
smaller scale thermal hydrologic tests at the site to
support and plus modeling and analyses of coupled thermal
chemical processes.
There are data to support a range of possible
effects associated with thermal hydro chemical mechanical
stress evolution at the site.
But it's fairly broad what the possible outcomes
are in terms of their effects on the rock properties, the
permeability, the fracture aperture, the capillary suction
in and around the drift.
Therefore, because of that complexity and because
of that uncertainty in what is the most reasonable, the most
defensible model for seepage in the effects of all these
coupled processes, a conservative assumption was taken that
take the flux five meters above the drift, I think the
bullet says there, and put that flux into the seepage model.
Don't try to capture all the nuances of what
happens in the first ten centimeters or the first millimeter
of the drift wall as the drifts are degrading with time.
So that's not uncertainty, it's not variable in
the model.
Is the actual seepage into a drift uncertain?
Yes, because the seepage model itself is uncertain and the
flux itself is very uncertain and highly variable.
But the coupled processes and the complexity
associated with those was, in this particular case,
eliminated by making this conservative assumption. I should
point out that that was, going back to the TSPA-VA, that
was, in fact, a recommendation of the peer review panel to
say in order -- the complexities associated with this one
are so large, you, department, may be better off simplifying
it and that's what we've done.
George is biting at the bit here.
MR. HORNBERGER: Just a quick question on that.
The TRB has been critical of this particular aspect and one
of the contentions is that some of this uncertainty may, in
fact, be diminished or go away if the temperature of the
repository were lower.
Can you give me the basis of that? Do you agree
with that contention and if so, what's the basis of reducing
the uncertainty? The coupled processes are still there, is
that right?
MR. ANDREWS: Yes. Even at 70-80 degrees C, you
still have coupled processes. You still have mechanical
processes at zero degrees C. As soon as you open that
drift, you have mechanical degradation processes that will
kick into gear and then you have the thermal hydrologic
coupled processes and the thermal chemical coupled
processes.
I can't speak for the board and their beliefs
about reducing uncertainty with cooler repositories. I
believe it's not totally tied to this particular one. I
mean, this is what gets the focus, but it's also on the
degradation characteristics of the engineered barriers in a
cooler -- where cooler now is 70, 80, 90 degrees C,
environment rather than 120, 130 degrees C.
So it's not solely in the rock that they're after.
MR. HORNBERGER: I'm not asking you to speak for
the board. I was just asking, in your experience in doing
TSPA, would the uncertainties be significantly reduced at
these lower temperatures?
MR. ANDREWS: No. We got enough uncertainty.
MR. GARRICK: It just may be displaced.
MR. ANDREWS: It might be displaced in time.
MR. GARRICK: Right.
MR. ANDREWS: I don't know if you want to pick up
any other of those that don't have checkmarks, but if I go
to the second page, for example, I think it's a useful one
on the waste form characteristics and the waste form
degradation.
There are a number of fairly complex processes
that occur once water, in whatever form it exists, whether
it's humid air or actual liquid water, when it comes into
contact with the waste form, there are very good data
collected at PNL, at Argonne, at Lawrence Livermore Labs,
and internationally about the degradation characteristics of
the waste forms.
Those data have been used, but they have a fairly
broad range and the applicability of that range under the
exact environments that we're expecting is uncertain. We
could have used that range or we could have used a more
bounding value.
What's there right now in Rev. 00 that we're
talking about is that more bounding value for the waste form
characteristic degradation.
I don't know if there's any -- in package
transport, that's another nice one. What the internals of
the package look like after the package has degraded, as a
function of time. The characteristics of the basket
material, the degradation of the basket material, the
stresses involved inside the package, the hydrology in the
package, the chemistry inside the package are very
uncertain, very uncertain.
And for anybody to confidently predict the
internals, with the exception of some basic fundamentals
like temperature, would be -- well, it would be difficult.
So a more bounded type approach was taken of bring
that mass, bring that activity, once the waste form is
altered, to the edge of the package, the inner edge of the
package.
So transport inside the package, transport along
fuel rods, transport through a degraded fuel rod assembly
was not taken credit for in the Rev. 0 TSPA-SR. And that
would require, obviously, a different model, different
representation, alternative conceptual model of how you
think the internals of the package perform over time.
It is much simpler, much more defensible to take
the more conservative approximation in this case.
By the way, most of these have limited effect,
where limited is small, effect on the post-closure
performance. WE did not make the collective decision of
where to add conservatism based on things that were highly
important to performance.
So it was generally focusing on those that were
less significant to performance. One exception to that is
this secondary phase issue that's a bullet on the waste form
degradation and solubility limits.
There's no other -- well, there's other
interesting ones in here, but maybe that -- I think those
examples, I think, are probably sufficient to walk through
the process, the collective decision-making that was done.
As Abe told you, each one of these are being
examined with this small group, evaluating is there --
should we look at quantifying this uncertainty and if we do,
should we then run a calculation to see what the impact of
that particular aspect on the system performance was.
I think taking Dr. Garrick's point to heart of now
that we have the tool, it's running, it works, we believe
giving reasonable results, now it's kind of time to exercise
the tool with alternative representations, gain additional
understanding.
MR. WYMER: It's a little disturbing to me that
most of the areas that are unchecked, or many of them, are
chemistry related areas and to a chemist, those don't look
any more difficult than some of the other complexities which
have been taken into account.
And in some of them, like second phase formation,
you may have quite a profound effect on the release of
radionuclides, where it would be significant in the dose to
the person at 20 kilometers.
So it seems to me that, from a prejudice point of
view, what I see is that reflection of the knowledge and
backgrounds of the people doing the study rather than
reflection of the difficulty of doing the analysis.
MR. ANDREWS: Well, there are a lot of good
geochemists working on this project and who have supported,
through their analysis and model reports, supported the
development of these inputs.
The one example you pointed to is a very near and
dear example to many of our hearts. It was an example that
we used in the VA, in the viability assessment. It's an
example we've had extended discussions on with the folks at
Argonne who are doing the detailed fuel testing and
characterization of the alteration phases of the fuel.
It's a point that I think has been made by NRC and
center staff with respect to review of Pena Blanca and
utility of Pena Blanca as a very valuable analog for waste
form degradation and mobilization and transport of some of
the actinides that we're talking about here.
MR. WYMER: There are other kinds of chemists than
geochemists, you know. There are inorganic chemists and
physiochemists who could give a good deal of insight here.
Geochemists have their own point of view.
MR. ANDREWS: Well, I'm not going to get into that
debate.
MR. WYMER: Unfortunately, I have one sitting next
to me.
MR. ANDREWS: But the point is well taken and I
think there are complexities associated with the controlling
phases as these materials degrade. There is complexity
associated with some fundamental thermodynamic information
on these controlling phases. Not so much on the uranium
side, but for -- when I put neptunium in them or plutonium
in them, those fundamental thermodynamic information, I
think, is -- I'm not a geochemist, so excuse my bias, but I
don't think some of that fundamental thermodynamic
information is available.
I think there was a presentation to the technical
review board in Reno by Dr. Glassly from Livermore and he
pointed that uncertainty out as well, that some of the basic
thermodynamic data is just not there, and I think the board
-- I forget -- one of the board members asked him, well, are
we pushing to get that kind of information, and his response
was, well, I hope so, but it sounds like fundamental
university type laboratory research to come up with those
data.
And in the absence of some of those thermodynamic
constants and time stability constants, it was difficult for
-- in the high defensibility role that we wanted to be in,
to take credit for some of those aspects.
Is there more that we could gain there? Sure as
heck is. And I think Dr. Ewing was a member of our peer
review panel or DOE's peer review panel, I should say, and
he, I think, shared your kind of comments on the VA. I
think they are throughout the VA comments.
It's pretty complex.
MR. WYMER: Yes. No more complex than some other
aspects, though, that are dealt with, in my judgment. But,
okay. I'm not going to beat a live horse.
MR. ANDREWS: Okay.
MR. GARRICK: By the way, Bob, these are excellent
exhibits. I must like matrices, because these are very
helpful.
MR. ANDREWS: Good. Okay. Now, we've set up the
stage. It's time to get to some results, preliminary
results.
The first result slide, John, why don't you go
ahead with the VA, puts it into context of what the TSPA-VA
result that's most comparable to the results that I'm going
to be showing to you.
In the VA, of course, we did not have Part 63 or
197 on the street as proposed regulations. I think they
came very shortly after the summer of '98.
However, there was enough discussion, I think,
with ACNW, with NRC staff, that we had fairly good knowledge
of what was going to be in the draft regulation when it came
out, which was a slightly different way than we were doing
most of our plots in the VA, quite frankly.
The how one does the expected, quote-unquote, the
dose -- just the mathematics of doing that calculation was
slightly different than the way we were proceeding in 95
percent of our plots that we presented in the VA.
But we had one set of plots, shown here, figure
4-28, that most closely represents for the nominal -- this
is nominal scenario class in the VA -- most closely
represents the way NRC ended up writing the proposed Part
63.
What I've shown here is the 95th percentile mean,
i.e., expected median and the 5th percentile is actually off
the curve. The 5th percentile was zero out to 100,000
years.
So it gives you an idea, backed with VA models, VA
assumptions, whether they were good, bad or indifferent, VA
design, this is the comparable VA, TSPA-VA result for the
slides that are going to be following. I did not change the
time access to be logged like the subsequent ones are.
There have been a lot of changes. As Abe pointed
out, there was a number of changes. There was hardly a
model that didn't change between the VA and the SR. The
design changed from the VA to the SR and in some cases, the
approach changed between the VA and SR.
So the following slides all relate to those 121
AMRs and their incorporation in the TSPA.
So let's skip to slide 24. What I've shown you
here or have up here are 300, the skinny little lines are
300 individual realizations of the total system performance
based on those 40 AMRs, cranking them through with their
uncertainty and their individual parameters and models, et
cetera.
So each one, each one of 300 has an equal
likelihood of occurring. We then superimposed on top of
those 300 four basic statistical measures of each one of
those, essentially done in a per year basis, where per year
really means, in this case, per time step and time step is
about 25 years.
So it's per time step slice and I've shown the
95th percentile, the mean or the expected value, the median
or the 50th percentile value, and the 5th percentile value.
Several things to note on this slide. One is
there is quite a wide spread, variance, if you will, of the
dose as a function of time. If I'd look at it at any
particular time, there is a wide variation of dose. If I
look at any particular dose, it's a wide variation of time.
So it's quite a wide spread. Understanding that
spread, that distribution of the results is an important
component of performance assessment, and we're going to
spend a little more time talking about that, why the broad
spread.
If you look at 100,000 years, that spread is going
over seven or eight orders of magnitude. It's very broad.
Another point of observation is in those 300
realizations, for the data that are contained within the
analysis model reports, for the models that are supported in
those analysis model reports, none of them had a failure of
the engineered barriers prior to 10,000 years in this
nominal scenario class.
We'll look at some examples in just a second where
that's not the case. It's not the case in the volcanic
event and it's not the case in human intrusion, but for the
nominal performance, the expected performance, with its
uncertainty embedded in there, none of them failed before
10,000 years.
Your logical question is, is it impossible to have
failures before 10,000 years, and the answer is clearly no.
There is a probability of having a degradation prior to
10,000 years, that we'll get to here in a second. But for
the nominal performance over that many realizations, there
were none.
You might ask how did you pick 300, why didn't you
use some other number. Well, our goal was to get a stable
mean, not a stable 5th percentile or a stable 95th
percentile, but a stable mean and we ran 100, 300 and 500
and 300 was stable enough, 500 was sitting right on top of
300. So we stopped at 300. Just totally economics related
to why 300 and not 500. They're one on top of each other.
The difference between 100 and 300 is not that
much, it's probably 20 or 30 percent, and we have those
plots in the technical report as backup.
Other points of information are probably best
explained by looking at the next slide.
MR. LEVENSON: Bob, before you leave that one. Is
that correct that the 95th percentile line crosses the mean?
MR. ANDREWS: Yes. And you'll see it also when we
get to volcanic, in a way, that the 95th percentile can
exceed the mean; i.e., the mean is driven by the top two or
three percentile of the distribution, which is what you're
seeing right there.
The next slide talks to the principal nuclides
that are controlling this dose rate and all I've done is
taken, for the expected value case, this is now expected, I
have to be careful here, this is expected value of the
output.
So this is based on -- still based on 300
realizations of the probable performance of the repository
system and I'm just looking at one expected value from that,
and then what are the nuclides that are controlling that
expected value.
And what you see here, quickly, is that up till 40
or 50,000 years, we are dominated by the very high
solubility, unretarded, diffusing radionuclides, like iodine
and technetium, same thing we had in the VA.
That at early times, those things that are
unretarded, those things with very high solubility which can
diffuse through thin films or long thin film boundaries,
they are released first.
After a while -- in this case, it ends up being
about 50,000 years -- it's the lower solubility, retarded,
but not completely retarded nuclides. They diffuse a little
bit, but they're more controlled by how much water advects
through the system, how much water advects through the
package and through the invert, neptunium and the colloidal
plutonium.
This is -- we have two colloidal plutonium species
that are being tracked in the TSPA-SR and those are the ones
that are coming out at longer times.
I should point out that a large fraction of the
inventory, of the total inventory is still retained either
in the waste form or in the waste package or in the EBS,
simply because of the very low solubility or very high
retardation characteristics of those other nuclides.
So what we see here is things coming out and
trying to understand why they come out and what is the order
in which they come out, but there's a lot of other things,
and I did not bring that plot, but we show the plot in the
technical report, that are retained and that are essentially
delayed significantly before they come out and provide any
kind of dose consequence.
There's a little bit of understanding that can go
into these plots, but that understanding really resides in
the backup slides. Part of it's clear that until you have
the primary containment barrier, i.e., the package, degraded
and you get water into the package, you have no release.
Even when you have the package degraded, and, generally, and
there's backup slides to point this out, for your benefit,
once the package degrades, it's generally degrading at the
closure welds.
It's generally degraded by stress corrosion
cracking at those closure welds. Those cracks are micron
size. So liquid water is not getting into those cracks.
There's an analysis model report to support that. But humid
air can get into those cracks and nuclides through humid air
condensing on the waste form itself and that other
conservative assumption that we talked about earlier, about
the innards of the package and how they're being treated,
nuclides can diffuse through those cracks in the stress
corrosion cracked welds of the earlier package failures.
So what you see here for iodine and technetium is
diffusion through very thin cracks, while the drip shield is
intact, but the packages have degraded at the closure welds.
At later times, the drip shields are degraded.
Liquid water for that fraction of the repository that has
seepage, which is depending on the timeframe and the climate
state and the percolation flux, et cetera, the fraction of
packages that see seepage changes with time.
But for that fraction that sees seep and for that
fraction where the drip shields have degraded and the
packages have degraded, liquid water can get into the
package and liquid water can take away nuclides from the
package, through the package, through the invert, and back
into the rock, and that's when you see neptunium and
plutonium taking over.
MR. GARRICK: Have you somewhere cast these into a
dose exceedence CCDF form?
MR. ANDREWS: No.
MR. GARRICK: That would be very -- that
communicates very well. I just wondered if you had
considered that, especially for the disruptive events which
have a recurrent cycle to them.
MR. ANDREWS: I appreciate that, John. We
struggled internally on communication of this and, quite
frankly, in polling people, obviously, we didn't poll you,
we concluded that CCDFs, although explanatory for some
fraction of the audience, were obfuscating for a large
fraction of the audience and, therefore, we -- including
people who were on our peer review panel before.
So reasonable people. So there was a transparent
--
MR. GARRICK: These are important curves, but from
a risk perspective, the CCDF is the risk curve, whereas
these are not.
MR. ANDREWS: Right.
MR. GARRICK: These are just probabilistic dose
curves.
MR. ANDREWS: These are risk when you multiply
them by .999, which is what these are.
MR. GARRICK: Yes. But I would think that
especially for the disruptive events, it would be a useful,
a very useful presentation to be able to --
MR. ANDREWS: That's a good suggestion.
MR. GARRICK: -- answer the question in one
diagram what the risk is.
MR. ANDREWS: That's a good suggestion. We had a
little dialogue with some other review groups on how to
prevent the disruptive event work, and that would be, I
think, a good suggestion. We have not implemented that yet.
MR. GARRICK: Okay.
MR. ANDREWS: Let me go on to slide 26, the one
looking at longer-term performance. This particular slide
and the one that follows, which talks about the key nuclides
associated with this slide, is the case of extrapolating
those models used in the 10,000, 100,000 year performance
results, extrapolating those models on out to a million
years.
We understand, as we read proposed 197, that that
maybe isn't exactly what they intended, but this shows what
the impacts of doing that would be.
We stopped at a million because of 197 saying that
was the time period of geologic stability, which is also the
time period the NAS thought was of geologic stability. I
think it reasonably captures the peak. You can see the
peaks are coming down as you go out past two or 300,000
years, coming down primarily because either things are
slowly but surely decaying.
Some of these nuclides have very long half-lives,
so they're still in the system or they're being absorbed or
they've come out of the system.
One thing -- I think that's probably enough to say
on that particular curve and the following curve.
Let's go to the disruptive events, the igneous
activity scenario class. This one. This is the one that I
think Abe said things were in checking or in review. This
is the curve that's different a little bit from the curve
that we presented in the beginning of August to the Nuclear
Waste Technical Review Board, and I'll walk through that
difference here in a second.
But before I do that, let me talk to the form and
structure of this particular set of curves. At the
left-hand side, you see some nice smooth responses. The
curves all more or less look the same. You just have a
distribution around a mean or around the median for those
curves.
Those curves are all the extrusive igneous event,
whereby the pathway is -- the event goes through the
repository, intersects the package, takes a fraction of the
waste up, entrains it, and then the wind blows south and the
waste is deposited over the landscape along with the ash and
the primary pathway is an inhalation type pathway associated
with that release.
So there is a wide uncertainty on those, being
driven by the number of packages that are hit, by the
probability of occurrence. These particular curves are
still sampling the probability of occurrence over that
distribution from the expert elicitation, uncertainty in the
wind speed, et cetera. So there is a distribution around
that.
Another thing I should point out on this is these
are probability weighted dose rates. These are not
deterministic doses, given the event occurs, what's the
dose. These are already factored into the analyses for
comparing apples and apples to make them comparable to the
other slides, have already factored that probability into
the dose rate.
So this really is a risk. So that 95th percentile
is 95th percentile not of the total distribution, I think
this is getting to your point where I think, John, it's a
really good suggestion, this is 95th percentile given the
event. So it's conditional.
And I think if you showed the complete, either as
a PDF or probably better, as you point out, as a CCDF, the
full distribution from probability one to probability
ten-to-the-minus-eight of dose consequences, you probably
would have a clear picture of the overall system, whereas by
probability weighting it, which is the way Part 63 asked us
to do it, but by probability weighting it, you've lost that
consequence time probability factor, because it's already in
there.
The third thing to point out, which is the reason
the slide changed from what we did before, is the right-hand
portion of the slide.
What I have shown here is actually 500
realizations, individual realizations, but there's actually
5,000 realizations that are behind this particular plot.
You say, well, my gosh, why did you go to 5,000 in this
case.
Well, the reason is in order to get a stable mean
on the dose consequences associated with the indirect
intrusive event, so the volcano goes -- well, it's not a
volcano, now it's a dike, the dike goes, intrudes the
repository, degrades the engineered barriers, and then the
natural system takes over.
The timing of when that event occurs, of course,
is very uncertain. So it's being stochastically sampled in
here. But the consequences are a function of the
uncertainty and all the other aspects of the system,
uncertainty in the unsaturated zone, uncertainty in the
saturated zone, uncertainty in colloids, uncertainty in
seepage, all the other uncertainties take over or get a
distribution of dose responses for the indirect intrusive
volcanic event.
And simply put, in order to get a stable mean, we
had to go to 5,000 realizations over a 50,000 year time
period. That's why the plot stops at 50,000 years. In
order to get a more reasonable stable mean, that's the red
line there, for the risks associated with the indirect
intrusive volcanic event.
So this curve is slightly different in the
presentation that we gave to the TRB back in the beginning
of August. We had, I don't know, 500 realizations, not
5,000 realizations, for this particular plot. So the plot
is a little different.
Let's see. The next plot essentially just
combines the two expected cases. So looking at the means of
the distribution of the nominal performance and the means of
the distribution of the igneous scenario classes, we
essentially just add them.
And these are now correctly weighted by the
probability. The probability, when I combined them, is one.
The probability of one is .999.
And you see for this case the predominance in the
first 10,000 years is driven by the low probability, but
high consequence igneous event scenario classes, something I
think the NRC has pointed out or alluded to in their review
of the VA and I think in earlier documentation that they
have produced.
MR. WYMER: Before you leave these curves, which
are very interesting, it occurs to me that with the
exception of the igneous activity curves, the other curves
all start at post-10,000 years, and that's because, I
presume, C-22 is considered to last that long before you get
any significant failures.
Ten thousand years is a long time and the database
for the corrosion of C-22 is not too large and you tend to
believe extrapolations like that when you have a good
understanding of the basic processes involved as opposed to
just measurements. You understand mechanisms.
How comfortable are you that you can believe that
it will not corrode for 10,000 years? How much do you know
about the fundamental corrosion processes of C-22?
MR. ANDREWS: Well, I'm probably not the best
person -- I'm not a C-22 expert.
MR. WYMER: This is fundamentally your whole
analysis.
MR. ANDREWS: Well, in the first 10,000 years, for
the nominal scenario class, yes, the degradation
characteristics of that waste package and the welds and the
stresses at the welds are what dominate the performance.
The analysis and model reports and the data and their
justification incorporating the uncertainty, and there is
uncertainty in the degradation characteristics, there is
uncertainty in the stress stage at the welds, there is
uncertainty in other mechanisms, other process mechanisms
that can lead to degradation of those engineered materials,
all of those are in the analysis model reports, plus a
description of their uncertainties and their basis.
In order to evaluate kind of the what if sort of
scenario that you're alluding to, I think, is we've done
several things. One, that I'm going to get to here in a
second, is that we looked at this barrier, as a barrier, and
looked at all of the component parts of that barrier that,
first off, are included.
So the things that we have included and their
uncertainty and pushed them to their -- all of the key ones
to their 95th percentile in order to see what happens, if
you will. That's one thing that we've done.
The other thing we've done is we've done, in
support of the repository safety strategy, we've done -- and
looking at this potential vulnerability, we've looked at
juvenile failures, quote-unquote, juvenile failure of the
package, and then done the same analyses off of those
juvenile failure packages that we've done for the nominal
packages.
MR. WYMER: Where you assume a limited number of
failures.
MR. ANDREWS: Right, assume a number have failed.
They fail with a patch kind of opening under a drip shield
and then we've sometimes failed the drip shield and the
package at the same time, just to gain an understanding for
how the system performs in the absence of that barrier, if
you will.
The other thing, of course, that we've done is --
MR. WYMER: What results do you get when you do
that?
MR. ANDREWS: Those are -- for a singular -- I
don't have them, at the top of my head. They're in the
document that's undergoing review right now. My
recollection is for a single package, it was, at 10,000
years, it was on the order of ten-to-the-minus-two or
ten-to-the-minus-three millirems for a package.
Abe, do you remember what the numbers were?
MR. VAN LUIK: I don't, but it sounds about right.
MR. ANDREWS: It's in that ballpark, anyway.
MR. WYMER: Okay. Thanks.
MR. GARRICK: While we're on that curve, which is
a very interesting one, given that the igneous event is now
controlling the risk through the time of compliance, does
that not bring up the whole issue of the design of the
repository in terms of how much you should invest in trying
to design a 12,000 year waste package? In other words,
aren't you in a situation here with a much more conventional
waste package wouldn't change the risk?
MR. ANDREWS: Well, if I had a much more
conventional waste package, I'm not sure that line on the
right would start appearing after 10,000 years.
MR. GARRICK: No, it wouldn't.
MR. ANDREWS: It would be significantly before.
MR. GARRICK: That's the point. It doesn't
matter.
MR. ANDREWS: For this.
MR. GARRICK: If you moved everything -- yes.
MR. ANDREWS: If I moved it significantly to the
left.
MR. GARRICK: It doesn't matter from a risk
perspective. You could get by with a lot less extravagant
repository design. Given that the risk is being driven by
something that you can't design out.
MR. ANDREWS: It's possible.
MR. GARRICK: Just something to think about. It
seems to me, as far as my paying for this, from a risk
standpoint, I'm paying a heck of a lot money, perhaps,
perhaps if the calculations haven't been done, to achieve a
level of performance that, from a risk perspective, is kind
of irrelevant.
MR. ANDREWS: I agree and that's very possible,
and I think Abe alluded to some design related sensitivity
analyses that are to be done. Right now, we have close to a
point design. It's a flexible design, but it's close to a
point design.
We are, this fall, probably going to do some
limited simplifications of that design, just to see what if,
I think to address questions like that.
Having done that, that's one step of performance
assessment, generating the curve and a series of curves.
Another, and, in fact, as important, maybe even more
important aspect of it is to evaluate why those curves are
the way they are.
Do the sensitivity analyses, do the statistical
analyses, do the barrier importance analyses, to gain an
understanding of what's going on and why is it going on.
So there's been a wide suite of these done in
support of the SRCR, first, and documented in the technical
report and documented in the repository safety strategy.
These start first off with basic statistical
evaluations, what drove the variance, what drove the mean,
what drove the top ten percentile, et cetera. There's a
wide variety of statistical techniques available and we've
used the ones that are most appropriate for our intended
purpose.
We've done then a large number of sensitivity
analyses, taking an individual factor, an individual
parameter and doing 95th-5th percentile sensitivity analyses
on that factor or parameter, trying to gain an
understanding, by factor, what is its contribution to the
system performance, always running out to the 100,000 year
time period.
Why 100,000 years? Well, 100,000 years was to go
sufficiently beyond 10,000 years to the point where the
engineered barriers were degrading, go sufficiently beyond
10,000 years to assure ourselves and the reviewers that
there was no significant degradation of any aspect of the
system beyond the 10,000 year regulatory time period.
So all the sensitivity analyses and barrier
importance analyses are also done out to 100,000 years, with
the exception of that 50,000 year volcanic event one.
The final set are what we've termed barrier
importance analyses and those are going barrier by barrier
and looking at, in two different ways, looking at either 5th
or 95th percentiles of the key aspects of that barrier, 5th
being on the good side of performance, 95th being on the bad
side of performance.
If that particular parameter, a low value, meant
bad performance, then we flipped it. So it's looking at
good or bad within the distributions that we have.
Finally, the last bullet there is in some cases,
for particular barriers, they were neutralized; i.e., the
function of that barrier was removed from the analysis to
evaluate the contribution of that barrier and all the other
barriers to the system performance.
Those were mostly used in support of the
defense-in-depth and multiple barrier determinations that
are embodied in the repository safety strategy.
The next three -- I'm going to go a little faster
here -- slides just talk through using the same orientation
I did in the previous table, which is the same table that's
in the back of the document, go through what's the barrier,
what's the barrier function, and what was the importance
analysis done on that barrier, where that performance
analysis here was that 95th-5th percentile aspect.
So you can read what aspects of the system were pushed to
their limits in that particular table.
The next slide, which is a results slide, walks
through some regression analyses, and these are supported in
a lot of different ways. I'm just showing you the
regression analyses of the nominal performance scenario to
what drove the variance.
So I'm trying to understand what drove that
six-eight orders of magnitude of variance of system response
for all of the uncertainty inputs that were put in there.
I think Abe already alluded to this one, but the
top four relate to the package. They relate to the welds of
the package and they relate to essentially stress corrosion
cracking at the welds of the package.
So that is a point of continued investigation,
continued discussion. I believe this issue came up,
although I was not able to attend, at the container life and
source term KTI meeting, about the importance of the stress
state at the welds and degradation mechanisms at the welds,
which includes the defects at the welds.
The other one is the saturated zone flux.
Having done that, it points to a few parameters of
the several hundred that are in the total system model to do
a barrier importance analysis on.
The next slide, the results slide, John, if you'd
just slip to that one, assumed -- you know, I took 95th
percentiles and 5th percentiles of those stress factors,
those corrosion rates, the defect distribution, the defect
orientation, the defect size, all of which are parameters in
the TSPA model, and pushed them to their 95th percentile,
and then ran 100 realizations, we only did 100 when we were
doing barrier importance analyses, 100 realizations and redo
a mean or expected value off of those 100 realizations.
And you can see that if we sample some of those
parameters at their close to extreme values, obviously not
the 99th percentile, but at their 95th percentile, we
generate early failures and when we generate early failures,
we get early releases through those stress cracks at the
welds.
These are all driven by the weld and degradation
at the weld and those are early and prior to 10,000 years.
With that, I have a few slides to just summarize,
but they more or less repeat what Abe had, first talking
about the major technical improvements and the major process
improvements and then, finally, summarize with where we are.
As I've said, the results are done, but in
checking and review, the document has not been delivered to
the Department of Energy yet for their acceptance. They
will, of course, do an acceptance review and we'll make
whatever changes in the document, in the analyses, in the
report as required, as they did with all the process model
reports.
So with that, I'll entertain any questions you
might have.
MR. GARRICK: Good. Thank you. Thank you very
much. That's a very interesting presentation.
Committee, any comments? Milt?
MR. LEVENSON: I had one comment, or a couple, on
the same issue. You discussed the degradation of the waste
container and it was very clear and I think probably is what
happens. You get a crack in a weld and et cetera.
But unfortunately, in one of the pieces of paper
we got a month or two ago, it said that the assumption was
made that when the container lost the ability to be helium
leak-tight, the assumption was made that 50 percent of the
container disappeared.
Now, that's quite in contrast to what you've said
and I can't give you the specific reference, but I know the
other committee members have read the same thing. So I was
a little -- what you're telling us is what's really in the
TSPA.
MR. ANDREWS: I don't know this helium leak test
issue.
MR. LEVENSON: Well, the problem is when -- that
they assumed when failure occurred, when it cracked through,
the 50 percent of the container disappeared, so the fuel was
immediately immersed.
MR. ANDREWS: No. I do believe -- well, I don't
know where that -- if it was a criticality -- that sounds
like an extreme assumption for criticality analysis
purposes, but I have no idea if that's the case.
MR. LEVENSON: It was supposed to be release. The
other question I have, which is somewhat related, is that
even at 10,000 or 15,000 years or whatever time we want, the
fuel is really the only heat source in the mountain and,
therefore, if humid air gets through a crack, why would you
expect condensation on what is the warmest thing in the
mountain?
MR. ANDREWS: That was one of those -- I think I
alluded to it, maybe not as directly as your question is
pointing out. The innards of the package and the hydrology,
other than the temperature, the hydrology and chemistry of
those innards of the package, that was simplified and
conservatively so for this particular iteration of the PA.
There have been analyses, supporting analyses of
the amount of heat that the waste form, in particular, the
commercial spent nuclear fuel waste forms.
This is not so much an issue with the glass or the
DOE spent nuclear fuel, which are much, much, much cooler.
The heat output is much smaller in those packages.
But for the commercial fuel, your point is well
taken and there are some analyses that talk about more or
less an eight to 15,000 year time period, the time period is
a function of burn-up and age-out of reactor and storage and
things like that.
One would expect the system that you just
described to occur, that the water, humid air, would never
condense on the waste form itself during that kind of time
period because of the heat that's being generated.
After that time period, the temperatures are so
evenly distributed across all aspects of the waste form, the
package, the innards, the basket materials, et cetera, that
taking any more credit beyond that time period would not be
very feasible.
MR. LEVENSON: Because there is no time period
that you can go to when the fuel is colder than the
mountain.
MR. ANDREWS: That's true, that's true.
MR. GARRICK: Ray?
MR. WYMER: No, I've said my piece.
MR. HORNBERGER: Bob, Abe was -- we got into that
discussion about the qualified -- I think you called it
qualified uncertainties, the issues that you were just
discussing.
How will you work that in after you do these
analyses? Do you have any idea how you'll work that into
the presentation? I mean, the idea would be, on some of the
issues, the kind that Milt was just referring to. These are
one-sided. So they're not symmetric.
MR. ANDREWS: There's a large number of them that
are not symmetric. Given that we've -- in fact, most of
them are probably not symmetric. We made -- and not just PA
doing the final crank turning, but we, the project, in these
various areas where those assumptions were made, made that
conscious decision to be on the conservative side of a
distribution.
Doing -- so that means we're on the -- whichever
side is conservative, I don't know if that's right or left,
but we're on the right side of the distribution and
everything is to the left side of that distribution, in
which case putting in the whole distribution, if it's
distribution, or alternatives, A/B kind of alternatives,
means we're pushing it to the left, pushing it to lower
doses, if you will.
And they'll probably be treated as sensitivity
analyses off of what we say here is a conservative
representation of how we think this system will evolve.
So there will probably be, in terms of the
documentation, and we haven't discussed this with the
department and they might have different ideas, and so Abe
probably should say something, but we probably would put it
into this alternative model representation.
The other alternative, of course, is -- maybe I
shouldn't go here, but we have EPA and NRC have slightly
different definitions that go after the word reasonable.
One talks about reasonable expectation, one talks
about reasonable assurance. It may very well be that some
of these issues that we're talking about fall into the
reasonable expectation kind of case, rather than a
reasonable assurance case where you really want very high
defensibility of your models and assumptions before you go
forward with a license.
And that kind of discussion is going on right now
within the department, but whether it's a sensitivity
analyses, whether you use it in this reasonable expectation,
whether they are used for peak dose kind of considerations.
You've been conservative during the time of
regulatory concern and let's say appropriately conservative
during the time period of regulatory concern, but after the
time period of regulatory concern, when you're looking at
geologic stability timeframes, perhaps you should put this
reasonable expectation argument in.
It's for the final environmental impact statement,
which, of course, goes along with the license application,
but it's serving a different purpose. Those peak doses are
serving a different purpose for a different audience.
Maybe that's an idea. I don't know. Abe, do you
want to -- it's kind of a policy question.
MR. VAN LUIK: It's a policy question, but I think
your answer was correct. We were discussing exactly that
issue.
MR. GARRICK: Abe, can you go to the mic and
repeat that?
MR. VAN LUIK: Your discussion is essentially, in
a nutshell, what we are trying to determine within the
department should be our approach between the case that will
actually evolve into the licensing case and also the larger
case for the peak dose, which is to satisfy NEPA and satisfy
197's reasonable expectation.
And they go out of their way to say that what
we're interested in is what you expect, the expected value
case, that they're not interested in details of our
distributions for that particular purpose.
So that's some of the internal discussions that
we're having and we'll make a decision on how that goes
forward before the time of SR.
But what you will see in the SRCR is basically
what Bob has shown you.
MR. HORNBERGER: Second question, Bob. Can you
summarize for me how information, let's say, derived from
analog studies makes its way into the TSPA analysis or is
that considered separate from the TSPA?
MR. ANDREWS: There's a couple of ways. That's a
good question. A lot of it, and most of the time, it's
confirmatory type information to lend support to the process
models that are the underpinning analysis model reports.
Most of the time, it's that, to help defend, if
you will, the quote-unquote, validity of those process
models.
So in that sense, it's not a direct parameter or
direct data set that's fed into PA.
There are examples where those analogs, in
addition to providing support, actually are used to support
some of the data. It's non-site data, not DOE data, but
literature, available information that's relevant and
applicable to be applied.
So it's incorporated within the process model
itself as a -- if you will, down at the process model, a
direct feed. By the time we see it in PA, by the time it's
gone through an abstraction and incorporation into the TSPA,
you probably have lost a little bit of that direct
one-to-one traceability from that data set, that analog data
set into the process model and through the process model
into the TSPA, but it's there.
So it's confirmatory for most of the cases, kind
of add confidence, confidence-builder.
MR. GARRICK: The committee has a lot of questions
that they would like to explore one day on the TSPA and I
think we're going to have to do that at a later time and
when we get down to maybe a lower level of the analysis.
I think this has been an excellent overview.
There's a great deal of interest here in how some of these
algorithms are actually applied and how some of the analysis
is done, and we'll look forward to covering those in other
meetings as we get more involved in the PMRs and the AMRs
and the input documents into the TSPA.
So we'll look -- and I have a lot of questions,
but we'll look to another time to do that.
I've had requests from two people. Andy, you have
a question? Go ahead, I'm sorry.
MR. CAMPBELL: Just a quick one, Bob. Do you
feel, does the program feel that in the transition from
TSPA-VA to TSPA-SR, the modeling and the approaches and what
gets incorporated into the models in terms of parameters has
become more conservative or do you think it's become a
little more realistic?
MR. ANDREWS: I think, in toto, it's become more
realistic. There's the few examples where a conservative --
if a conservative assumption was made in the SR, it was
probably also being made in the VA.
MR. CAMPBELL: The reason I ask is it looks like
the dose curves have increased. At any one time, you get
higher doses in the TSPA-SR by, in some cases, almost a
factor of ten, if you look at the mean or the 95th
percentile.
If you're becoming less conservative, shouldn't
the doses be going down?
MR. ANDREWS: No, more realistic.
MR. CAMPBELL: If you're becoming more realistic.
MR. ANDREWS: I think the one aspect of the system
that's driving -- or a significant difference that drives
that is the solubility distribution, in particular, for
neptunium, because neptunium is what's driving the 100,000
year and, in fact, the peak dose.
In the VA, we tried to broaden that uncertainty to
incorporate both the waste form degradation characteristics
and the data from Argonne and PNL and Livermore, but mostly
from Argonne, as well as the direct observations of
solubility from Los Alamos and Berkeley.
So we had all the labs doing varying parts of
neptunium solubility work, which made it a fairly broad
distribution, had some lower values, had a few higher, but
mostly, on toto, was lower than what we have in the SR.
There were comments on the VA saying make the
solubility more chemistry dependent and we made the
solubility more chemistry dependent.
And in those analyses and model reports that
relate to the chemistry dependence of neptunium solubility,
the currently available data and fundamental thermodynamic
data pointed to a very strong pH. dependency which is
incorporated in the model, which meant, by doing so, the
solubilities ultimately were increased from what we had in
the VA.
So I think it's reasonable, defensible, but higher
value.
MR. LEVENSON: As a follow-up question, I
understand the technetium solubility is from real data.
What about technetium retention as it moves through the
ground? There is an assumption that is not related to, I
think, experimental data.
MR. ANDREWS: Now, there are technetium, neptunium
and technetium, there are retardation data for both of them
from Los Alamos, with site-specific kinds of materials.
The technetium retention in the alluvium is being
considered in the TSPA-SR, as is neptunium retention through
the whole system is being considered in the TSPA-SR, based
on best available data on those retention characteristics.
So if they're retarded, they're with data that
support them, they are in there.
MR. GARRICK: Okay. Speaking of intrusion, we're
getting into our lunch period. But as I was about to say,
we've had two people ask for an opportunity to make a few
comments and I would like to get those in and I would like
to limit the comments to three to five minutes.
Is Mr. Harney here? He's not here. All right.
Then Judy. Judy Treichel, of the Nevada Nuclear Waste Task
Force, would like to make a comment.
MS. TREICHEL: Judy Treichel, Nevada Nuclear Waste
Task Force.
You said that you were coming here so that you
could hear from us and I want to find out how that works,
because you are hearing.
I've got questions on the pyramid that I guess you
have in color and the rest of us got in black and white,
that shows the -- where we're at and where we're going and
all of that sort of thing.
I want to know, because the SRCR is supposed to be
a featured event in our lives very soon, how big is that?
Are we talking telephone book, something like this, are we
talking site characterization plan? How tall is that thing
expected to be? It's two volumes.
MR. SCOTT: I believe it's about 1,300 to 1,400
pages.
MR. GARRICK: You're going to have to use a
microphone and announce who you are.
MR. SCOTT: Mike Scott, M&O. I believe Tim
Sullivan, with DOE, said this morning it would be about
1,400 pages.
MS. TREICHEL: Okay. So probably about like the
draft EIS. Then am I correct that when the site
characterization -- when the site recommendation report
itself comes out, you just slap two additional volumes on
there? Those first two go as they are and you put two more,
or are you going to rewrite the first two?
Here's one and two, and then three and four come
in. Does all of this in this hunk stay the same or are you
making changes before you go to the Secretary and the
President, after we've had our chance to comment?
MR. VAN LUIK: The idea is that we would actually
listen to the comments, consider them, and make changes in
the documents before they go to the Secretary.
MS. TREICHEL: So it's up to us to get this site
recommendation all ready to go, because you were asked if it
was going to be reviewed and it appeared that was kind of
iffy and you weren't too sure about that.
MR. VAN LUIK: Ninety days.
MS. TREICHEL: For us.
MR. VAN LUIK: Uh-huh.
MS. TREICHEL: And that's interesting, too,
because during those 90 days, which, of course, we're pretty
used to, you have all of the major holidays and you still
got -- and we -- and in addition, we have no EPA rule, we
have no NRC rule, we have no DOE guideline.
So I'm not sure why, if we were doing a bona fide
job of reviewing this thing, we wouldn't review it against
the existing rules, that we wouldn't just take 60, we
wouldn't take 960 and see if it passes muster, because
that's what's there. We won't have anything new.
At the same time, while we're doing this exercise,
we're going to have eight technical exchanges that are going
on that are trying to bring about sort of resolution or
clarification or whatever you want to call it, changing the
status of your KTIs and the questions that people have.
So those are going on and we do those all at the
same time. In addition, the other myriad of meetings that
happened in which everything changes.
There was information you got today from DOE
that's a little bit different than what we've seen before
and the design is always different in one degree or another.
It was a little different today because of a difference in
the stainless steel part of the package. And we know that
that's not going to get frozen.
So I guess what I'm trying to figure out is
whether or not I'm spinning my wheels. The public doesn't
get paid. So we have to kind of save on what we spend, and
that includes our energy. And I just don't want to wind up
out there with something that means nothing, and maybe
there's other more important things going on.
So thank you for listening.
MR. GARRICK: Thank you. Thank you very much.
All right. Unless there's comments from anybody, I think we
will adjourn for lunch. Try to be back here as close to
1:00 as possible.
[Whereupon, at 12:05 p.m., the meeting was
recessed, to reconvene this same day at 1:00 p.m.]. AFTERNOON SESSION
[1:05 p.m.]
MR. GARRICK: We'd like our meeting to come to
order. For the benefit of those on the panel or on the
committee that are chemically inclined, this is their time
to shine.
We're going to, this afternoon, spend a good deal
of time on chemical related issues and to actually lead the
discussion and questioning on this will be Dr. Wymer.
Our first speaker is going to be Dr. William
Boyle, and I think, unless there's anybody that wants to
make any preliminary comments, we'll get right into it.
MR. BOYLE: Good afternoon and thank you for this
opportunity. You can see the names on the sheet here. I'll
be very brief and just mainly provide an introduction as to
why DOE wanted to make these other measurements of
chlorine-36.
I will be followed by Dr. Mark Peters, of Los
Alamos, who will provide the technical details, and the
actual work is being done by the principal investigators who
are listed at the bottom, most of whom are here, Mark Caffee
from Livermore is here, June Fabryka-Martin from Los Alamos
is here, Mel Gascogne from AECL is not, and Zell Peterman of
the USGS is here, and Robert Roback of Los Alamos is here.
So if there's questions on the details, the
investigators are here.
For those of you who were present in Pahrump in
May for the NWTRB meeting, I've got the same sheets, so it
will be repetitive for you.
I assume most of the audience knows why the
project has measured chlorine-36, but just in case, I will
give a non-expert synopsis.
Chlorine-36 is one of many naturally occurring
radioisotopes used for age dating. Its abundance was
changed my nuclear weapons testing in the South Pacific in
the 1950s, creating a bomb pulse.
Measurements of chlorine-36 at Yucca Mountain have
been interpreted to have this bomb pulse. These bomb pulse
data, at depth, are then used as evidence that there are
vast flow paths in the unsaturated zone at Yucca Mountain.
That's the synopsis, and now I'll go on to why we
did the validation measurements.
The project's original measurements for
chlorine-36 were done by Los Alamos National Lab. As you
can see, there are other organizations involved now in the
validation measurements.
And why were these validation measurements made?
Well, about two years ago or even a little bit longer, a
series of reports were written by the United States
Geological Survey that seemed to describe a comprehensive
history over geologic time about the unsaturated zone at
Yucca Mountain.
This history was based upon the integration of
many independent data sets. Not surprisingly, not every
data set that was used to develop the integrated history
flanged up perfectly.
One of the data sets that did not flange up as
well as some of the others is the chlorine-36 results from
Los Alamos National Lab.
In discussions about why there might be this
difference between the chlorine-36 data set and the USGS
history for Yucca Mountain, it was decided initially to
follow a standard scientific practice and have an
independent group make measurements of the chlorine-36, and
those independent measurements are those by Mark Caffee and
the others listed on the sheet, not from Los Alamos.
So we went ahead and made the measurements and now
you will get to hear the results of those. At this point, I
will turn it over to Mark Peters.
MR. PETERS: Thanks for having me. I do work for
Los Alamos, but I'm really up here as a representative for
the team that Bill mentioned is out there in the audience.
So I'll go through a lot of the technical details, but I'm
hoping to get through it, leave a lot of time for questions,
and then the PIs in the audience I've already told to feel
free to step up and help me answer some of the details,
clarify, however you all want to work that. That's up to
you.
Bill already mentioned the participants. They're
all sitting in the audience today, which is real nice. What
I want to do today is walk you through, first, a lot of you
are familiar with the chlorine-36 studies that we've done
over the past three to four years. I want to bring you back
up to speed on what that data set looks like, then go into
some of the results from the validation study, where we're
doing analyses of samples from some of the locations in the
ESF, where we thought we saw bomb pulse, and then bring in
some cross drift results and then wrap up with the path
forward, because as I'm going to show you, there are some
differences in the analyses for chlorine-36 chloride ratios
for some of the samples in the ESF set of samples from the
Sundance fault and we have a path forward that we're
following to try to address those differences.
As I'm going through, I want to clarify, so we
don't get lost in semantics. I'm going to be talking a lot
about sampling, processing, and analysis.
When I mean sampling, I mean physically taking the
sample from the rock and then processing, I mean what we
have to go through in the laboratory to process the sample,
fairly labor intensive, and then the analysis is done by
accelerator; in the case of Livermore, at Livermore; in the
case of Los Alamos, it's sent to Purdue University.
So, first -- and I should also say that there's a
lot of organization-specific references. You'll see a lot
of Los Alamos and Livermore. We are working as a team, but
it helps me distinguish between the data sets to point that
out. So this is an integrated study that we're carrying
forward with.
In terms of the overall objectives of the
chlorine-36 chloride program over the past three to four
years, the objectives are shown here. We were looking to
test alternative conceptual models for unsaturated zone flow
and transport.
Specifically, to look at flow and transport through the
Paintbrush tuff, the Paintbrush, non-welded, which sits
stratographically above the repository horizon.
Then also to look at the significance of differing
temporal and spatial scales. And what I mean by that is the
effects of episodic infiltration and how well the PTN might
dampen that flow into the repository horizon.
The program focused on systematic samples. Parts
of the ESF, we took samples every 100 meters, and then in
some cases, every 200 meters. We also looked at features,
meaning fault zone fracture sets and took samples, and there
we were taking block samples, large samples, with a pick
hammer or jackhammer, taking those back to the laboratory.
Bill mentioned the validation study. In the
validation study, we were focused -- and I'll show you the
data from the ESF in a minute, but one of the locations in
the ESF that we saw apparent bomb pulse was in the Sundance
fault zone. I'll show that on a map, but it sits down in
the main run of the ESF, down by Alcove 6, for those of you
who are familiar with the ESF.
We took -- and also at the drill hole wash fault,
but I'll talk mainly about the data from the Sundance today.
Those samples were taken by drill. We did bore
holes. So there was a difference in sampling approach for
the validation study than in the studies that we've been
doing over the program in the past couple of years.
Again, it was led by the USGS, with involvement of
Los Alamos, Livermore and AECL.
We were also looking at some of the samples, in
addition to looking at chloride-36, chloride measurements.
WE also have some tritium analyses that I will talk about
briefly.
But what we did is we did systematic bore holes
across those two fault zones, two-inch cores, up to four
meters, and, again, to emphasize, it was in contrast to the
sampling approaches that we took in the ESF and in the cross
drift.
So we took samples as depth slices and splits were
taken. So in some cases, we have Livermore and Los Alamos
looking at some were core and some were hole.
I mentioned I want to talk about the cross drift.
I call this validation, maybe I should put it in quotes, but
nonetheless, in the cross drift, we also did feature-based
sampling, but here we were able to do predictions using the
UZ flow and transport model for what we thought we would see
in terms of chlorine-36 chloride systematics and we compared
those predictions.
So background for chlorine-36, Bill alluded to it
to some extent. Chlorine, this is basically lifted out of
the table already, nuclides, chlorine-35, chlorine-37, both
stable isotopes, make up the full abundance. Chlorine-36
has a half-life of 301,000 years.
In terms of sources in the subsurface, you've
really got three primary sources. You have the pre-bomb
ratio, the modern ratio is about 500-ten-to-the-minus-15.
That has varied through time due to variation in the field
strength, the magnetic field strength on the earth, you get
more or less cosmic ray bombardment, therefore, more or less
chlorine-36 production in the atmosphere that rains down.
B bomb pulse has a much higher ratio. Then C,
there's a contribution from production of it due to
reactions, nuclear reactions with uranium and thorium in the
subsurface.
That ratio is much lower, 20 to
50-times-ten-to-the-minus-15, and that tends to be a
negligible contribution. All in all, those three sources,
there are some other minor sources, but they add up to what
you see in the subsurface rocks and water and what we then
measure.
Now, to go back to what we've seen in the ESF, the
exploratory studies facility. This plot is on the Y.
Chlorine-36, the chloride ratio, times-ten-to-the-minus-15,
has a function of construction stations, so that's thousands
of meters through the ESF. The north ramp, the main drift
and the south ramp are shown along the top.
There are several different kinds of samples shown
here. This is the Los Alamos results. So you have, in the
black squares, you have the systematic samples. The open
squares are the feature-based samples, then there's also
core water samples, where we've done -- we've extracted
water using centrifuge and done analyses of that water.
Then there is also plotted on here, in the red are
the Los Alamos validation samples, meaning the splits of the
core from the validation work at the Sundance.
But you can see, in general, where we see apparent
bomb pulse ratios, which were above
1,200-ten-to-the-minus-15. It tends to be associated with
structural features.
So we chose the Sundance and the Drill Hole Wash
to do our systematic validation study across there.
So just to come back to the validation work. The
goal here was to verify the presence of bomb pulse in
samples taken from the ESF and the sample preparation method
that was developed, that Livermore is using, is designed to
detect the presence of bomb pulse. So we weren't looking to
delineate the relative contributions from those three
sources, but we were mainly looking for any evidence of bomb
pulse chlorine-36 in ESF.
This is the data for the Livermore results.
Again, we did a series of bore holes across the Sundance
fault. This is chlorine-36 to chloride
times-ten-to-the-minus-15 on the Y; again, plotted against
ESF station.
We did a series -- we did on the order of over 40
bore holes across the structure and you can see the data
there. So the present day ratio is shown about
500-ten-to-the-minus-15, ratios greater than 1,200,
indicative of bomb pulse.
You can see the Livermore analyses are all
relatively low, in the 50 to 200-times-ten-to-the-minus-15
range. No evidence of bomb pulse.
Now, for the Los Alamos results from the
validation study. This is, again, a similar plot, same
ratio plotted on the Y against ESF station, with the
Sundance fault drawn in the -- the Sundance is right here.
And here is the sampling interval. WE sampled across the
fault with the bore holes.
What's plotted here in the blue diamonds is data
from the -- what I'll call the standard ESF study and then
in the red squares are the validation results from Los
Alamos.
We haven't seen evidence -- we haven't seen ratios
greater than 1,200, but notice there is a difference. All
the samples are greater than 500-ten-to-the-minus-15, so
you've got a significant difference in ratio there between
what Livermore was getting for similar samples.
You have to ask yourself, okay, what -- well,
that's really the crux of why we're here. We've got two
data sets now that are showing some differences. How robust
are the Livermore data? When you correct for blanks, you
don't really affect the final ratio. In general, when you
correct the ratios for things, you tend to lower rather than
raise the ratio.
However, and I will talk more about this, if you
correct for rock chloride, which might be related to sample
processing, processing in the laboratory, it may be possible
that you could cause the correction to go in the other
direction, but that's what we're about in our path forward
trying to figure out what's really going on, particularly in
the processing techniques. That may be part of the
differences.
But I should also mention the Livermore --
Livermore runs samples from all over the world for a lot of
different reasons and when the samples that were run at the
same timeframe yielded results that were consistent with
what they expected for the geologic setting.
So we have no reason to believe that the Livermore
data is wrong or the Los Alamos data is wrong. We need to
look into the details of how we process the samples.
MR. GARRICK: Were the sampling procedures exactly
the same?
MR. PETERS: Do you mean sampling in the field or
processing in the laboratory?
MR. GARRICK: I mean in the field.
MR. PETERS: Yes. It was taken from the same bore
hole. So they were dry drill bore holes and then the core
was simply split for the validation study.
MR. GARRICK: And were they governed by any kind
of a national or international standard for taking such
samples?
MR. PETERS: They were collected, according to our
QA program, like we sampled all the samples underground. So
it's proceduralized.
MR. GARRICK: They both used the same QA program.
MR. PETERS: The collection in the field was the
same program, because it was the same driller, same drill
rig, same sample handlers.
So where we're headed here is how one -- what's
going on downstream of that.
MR. GARRICK: And those same questions we'll want
to talk about downstream.
MR. PETERS: Right. And the details of that are
better spoken to by the PIs. I'm not going to say a whole
lot more than what I've already said, actually. But we do
have a path forward that focuses on that part of the process
to see if that's -- that therein lies the difference.
I mentioned at the beginning that we're looking --
there's some related work associated with the validation
study. For example, we're also looking at doing tritium
analysis in some of the same samples, and here we're
extracting the water and doing tritium analyses.
This is a slightly out-of-date slide. The USGS
has done additional analyses, but suffice it to say it
doesn't change the distribution.
So right now we've seen really only one sample
that's even above detection limit for tritium.
So for the validation samples, no events of bomb
pulse tritium. But tritium and chlorine-36 are going to act
very differently in the unsaturated zone hydrologic system.
MR. HORNBERGER: Is the processing for tritium
similar to the processing for chlorine-36?
MR. PETERS: The tritium was all through
centrifuge. You extracted the water with the centrifuge --
distillation, excuse me. So vacuum distillation. So
basically putting -- moving it around in a cold trap in a
vacuum line, basically, whereas chlorine-36, as you know, is
basically running DI through some variation on that theme.
AECL's participation is mainly focused on the
U-series disequilibria work that they're doing. This
doesn't -- it speaks a lot to the -- basically, the
residence time of core water in the unsaturated zone. It
doesn't speak as much to bomb pulse, but it combines real
nice in with geochemical indicators of long-term percolation
flux, et cetera.
But we are seeing that thorium, uranium and radium
are in secular equilibrium. Therefore, they haven't been
moving around over the past 100,000 years.
The 234-238 uranium ratios are depleted, show a
five percent depletion in uranium-234, which suggests that
uranium-234 may be lost to pore fluids and that's probably
by alpha recoil.
And therefore, we would expect the pore fluids to
be enriched in 234, and they, in fact, are. So that can
actually be modeled to give us an idea of residence time of
the core water in the unsaturated zone.
Now, getting back to the differences. We haven't
finished. As Bill mentioned, it's a work in progress. It
is a work in progress. It's going to continue next year.
Livermore may yet see bomb pulse in some of the samples.
Mark made this point in May, and it's a good one.
Work to date hasn't demonstrated its absence. We just
simply haven't found it. It could be that we may find it.
The Livermore sample processing may have selected
phases that don't contain bomb pulse chlorine-36 or maybe
the samples may not, in fact, have bomb pulse chlorine-36 in
them.
But at any rate, the chlorine-36 concentrations
seem to be comparable, but the difference in ratios may be
due to, and this is a may, this is what we're going after,
elevated concentrations, chlorine concentrations, because
obviously we're reporting chlorine-36 to chloride ratios, so
you can -- there's a lot of leverage with chloride
concentration there to change that ratio pretty
dramatically.
So the differences, again, may be related to
processing method. We're focusing on that, not sampling or
analytical methods. So sample crushing, how you extract the
chloride for analysis, and those kinds of things.
I've mentioned, we've talked mostly about the ESF,
but this data, I don't think you've probably seen this data
in a meeting. This is data from the cross drift; again,
same ratio along the Y for the cross drift station in 100
meter increments, and the same familiar dotted line bounds
the range of current day values for chlorine-36 to chloride
ratios.
There's the faults noted in the cross drift, as
mapped in the cross drift, and you can see there, again, and
these are back to taking feature-based block samples through
the cross drift, so back to the standard ESF program, and
it's consistent with what we've seen throughout the ESF,
that Los Alamos has seen throughout the ESF.
So really what we're focusing in on is why are we
getting the differences in the validation samples.
So I've already said this, but we did do a set of
predictions for the cross drift and, in general, they were
consistent with the predictions for where we would see
background levels and where we would see bomb pulse.
And I said the second bullet already, but the
sampling protocol that we use in the cross drift seems to --
it does yield similar results to what see in the ESF
investigations, except for the validation study, as we've
talked about a lot.
So what about a path forward? There was a lot of
discussion amongst the PIs in the April-May timeframe,
particularly after the interactions with the TRB about how
to go forward and address these differences.
So the path forward is the USGS has prepared a
reference sample. We've taken some muck from the cross
drift excavations that we were doing back in that timeframe.
That's been crushed, homogenized, and then aliquots have
been distributed to both Livermore and Los Alamos.
There's going to be a set of experiments done by
both laboratories to test for the effects of different
leaching procedures on the release of rock chloride, again,
the chloride could be the key. That's ongoing. So this is
really, again, a progress report.
We will then do the laboratory work, do the
accelerator analyses and see where we're at, compare notes.
Once we've sort of agreed on a standard processing
method, we hope there will be exchange of samples, exchange
of information, apply that to the reference sample and the
validation samples, and then the results will be
synthesized.
Now, I haven't talked too much about the
conceptual model, but the ESF and cross drift data, except
for the validation data, has been incorporated into our
thinking on conceptual models for unsaturated zone flow and
transport.
So depending upon which way things go with the
validation samples, that could have implications for our
understanding of the conceptual model.
The three bullets are meant to address the aspects
of the conceptual model that will be under discussion,
depending upon the results of that study, frequency of fast
flow paths, roles of fault and fractures, particularly ones
that cut through the PTN, the non-welded unit above the
repository horizon, and then, finally, pore water ages and
implications for infiltration and percolation. The chloride
data is also very key. That's used heavily as a calibration
tool for the flow field in the unsaturated zone.
So this is all tied together. It's a little
premature for us to really say much about what it means for
conceptual model until we get at what the differences are in
the data sets.
So maybe this time next year we can tell you, give
you a final answer on that.
That's all I have.
MR. WYMER: Milt, questions? Okay. I'll start
out, then. Obviously, it is extremely important to
understand these data, because they do bear on one of the
most important parts of the whole repository; namely, how
fast is the water moving and by what mechanisms, and you've
known about the disparity quite a while.
What is it about the analyses that takes so long
to cross-check and confirm? It seems to me that could have
been done by now.
MR. PETERS: Well, the differences really were
just exposed in the spring. We just really started to
understand that there were some significant differences in
the spring timeframe.
MR. WYMER: Three months.
MR. PETERS: I understand.
MR. WYMER: Four months.
MR. PETERS: There's been some constraints. There
hasn't been as much work done at the laboratories because of
other competing priorities associated with AMRs and stuff.
I mean, it's project priorities, to some extent, that have
caused not as much laboratory work to be done in this area.
That may not be what you want to hear, but that's
the reality.
MR. WYMER: You're right. Okay. Well, that's my
question. Milt?
MR. LEVENSON: Yes. I've got a couple of
questions. The numbers that you have for the ratios, one
for the pre-bomb and the other for the bomb pulse, are those
average for the entire atmosphere, the 500 and the 1,200?
MR. PETERS: Let me be clear. The actual ratio --
that wasn't clear on the slide. The actual ratio for bomb
pulse water is much higher. That 1,200-ten-to-the-minus-15
is what we see when we take a sample of rock in the ESF. We
think anything above that is bomb pulse.
But the ratio for the actual bomb pulse chloride
is two orders of magnitude greater.
MR. LEVENSON: So the atmosphere concentration, if
you sample the air anyplace, it's going to be two orders of
magnitude higher than that.
MR. PETERS: For the bomb -- June, help me out
here maybe.
MS. FABRYKA-MARTIN: The ratio of 500 for
background is based on samples from the Yucca Mountain area,
actually the Yucca Mountain region. It's based on three
types of samples; soil profiles, for one, where once we get
below the bomb pulse in the soil profile, then we use those
-- the numbers that are clearly below where the pulse is as
part of the database.
The second source of samples are packrat samples
from packrat urine, that's fossilized. We carbon date the
sticks that are stuck in the midden and then use the
chlorine-36, the ones that clearly aren't recent, to show us
what the background has been.
And then the third type of sample is ground water
itself that doesn't have any tritium or C-14 indicating
absence of bomb pulse there, as well.
All three sources have been consistent in defining
that background.
Now, the 1,200 is a statistically derived
threshold. So we're saying that once it's above 1,200, then
we're confident that it's unambiguous evidence that it's
clearly elevated above natural background, and that's based
on a database of about 300 results from the tunnel and it's
also supported by our packrat midden samples where we never
saw any ratios as we went back to as far as 35,000 years.
None of those carbon dated samples were ever
higher than about a thousand or 1,100 or so
times-to-the-minus-15.
MR. LEVENSON: But I still don't have an answer to
my question as to what the source term is. What is the
ratio in the atmosphere from bomb debris?
MS. FABRYKA-MARTIN: Why do you care? I mean,
because --
MR. LEVENSON: Why do I care?
MS. FABRYKA-MARTIN: Because once it hits -- as
soon as it hits --
MR. LEVENSON: Because how do I know how credible
your 1,200 is if I don't know the source term?
MS. FABRYKA-MARTIN: The thought I had -- well,
first of all, it would be hard to collect a sample from the
atmosphere that did not have bomb pulse in it.
MR. LEVENSON: No, no. I don't want the
background from the atmosphere. I want the present
concentration of bomb pulse in the world, the source term
for this.
MS. FABRYKA-MARTIN: Okay. We do have samples of
runoff water, would you accept that? Runoff catched from
channels from USGS investigators?
MR. LEVENSON: If that's the best you can do. Is
that what you consider representative of the atmosphere?
MS. FABRYKA-MARTIN: No. No.
MR. LEVENSON: The source of the bomb --
MS. FABRYKA-MARTIN: The reason I say that is the
moment that a drop of water reaches the surface, it's
already being diluted by what's already there, what's
accumulated there over the thousand -- or hundreds of years
or tens of years.
So I'm not sure what --
MR. CAFFEE: Not to disagree with anything June
said, but one of the --
MR. GARRICK: Identify yourself, please.
MR. CAFFEE: My name is Mark Caffee, from Lawrence
Livermore National Lab. We can recreate what the bomb pulse
input is from looking at ice core data. So there's been
extensive studies of chlorine-36 deposition at the Vostock
ice core and in Greenland ice core samples.
So we can go -- we have gone back, these studies
have been done by a number of groups, and reconstruct that
profile of the bomb pulse chlorine-36 in the atmosphere.
I'm positive that I didn't bring a viewgraph of
that with me, but the chlorine-36 to chloride ratios are
very, very high and what you see is kind of what you expect,
that a few years after the atmospheric testing of nuclear
weapons, you had a peak in the chlorine-36 and then it has
fallen off since.
I don't know if that answers your question, but
that's kind of the --
MR. LEVENSON: What's the current day, current day
ratio?
MR. CAFFEE: If you just went out and got
precipitation, it would be back to what it was before the
bomb pulse, before the bombs were exploded.
MR. GARRICK: If you want to comment, you have to
do it in a mic.
MR. CAFFEE: What June was going to say is someone
has looked at precipitation in the environ of Purdue
University and for what we believe the pre-bomb chlorine-36
to chloride ratio was, it has gotten back to that again.
But it's not the case that there have been
thousands of measurements of chlorine-36 to chloride ratio
in rain waters all across the country or all across Africa
or anything. These contours of input are drawn based on not
a great deal of data points.
MR. LEVENSON: What's the precision and accuracy
to one significant figure of these analytical methods for
this ratio?
MR. CAFFEE: Okay. I'll answer for Livermore. I
won't try to answer for anybody else. The measurement
itself is much better than five percent, based on counting
statistics. By the time we fold in blank corrections, and I
can address the Livermore data here, the uncertainties may
go a little above five percent, but they're probably still
less than ten percent.
MR. LEVENSON: Five percent is the precision or
the accuracy?
MR. CAFFEE: Precision.
MR. LEVENSON: What's the accuracy?
MR. CAFFEE: I don't know how to answer that
question.
MR. LEVENSON: That's the most important question
here.
MR. CAFFEE: Of course it is, but what we're
trying to do, I can tell you that other samples, not Yucca
Mountain samples, but other samples, for example, in situ
chlorine-36 produced in carbonates in Greece and Italy and
all across the world have reproducibilities that are
comparable to our precision.
So for samples where we have a long history of
running things and our researchers have sent us duplicates
and triplicates, we believe that our accuracy is comparable
to the precision.
But for me to get up here and tell you that our
numbers at Livermore are absolutely accurate and there can
be no other circumstances that can change those ratios, I
can't answer that -- I can't do that.
MR. LEVENSON: Let me ask one other question,
which is a completely different type, because I was at the
meeting in Pahrump four months ago when this first came up
and there was discussion then that the simplest thing to do
was to take some aliquots from a processed sample and run it
both places and rather quickly eliminate whether the
analytical method was relevant or not, and it doesn't sound
like that has been done yet. Is that correct?
MR. CAFFEE: No, we have not done that. I don't
recall -- that was quite a while ago. I don't recall it
being mentioned. I don't doubt that it was mentioned. I
would, again, in answer to that, say that over a course of
six years of running, we have run duplicates of aliquots
many, many times, from meteorite samples, lunar samples,
rock samples from all over the world, and secondary
standards, NIST standards, a whole variety of things and we
have comparisons with samples run between ourselves and
Zurich, between ourselves and the old lab at Rochester, and
I even believe between ourselves and Purdue.
MR. LEVENSON: But that's not really the issue.
The issue is to try to resolve why the difference and it
potentially --
MR. CAFFEE: I'm not disagreeing.
MR. LEVENSON: You've attempted to get rid of the
sampling difference by splitting a sample. I think that's
an acceptable method of doing it, and you could fairly
quickly resolve whether it's processing or analysis by the
two labs running the same sample. I just don't understand
why --
MR. CAFFEE: This is one of the things that will
certainly be done with this standard reference material,
because here we have enough sample that we can precipitate
enough silver chloride that we can make splits.
The chemistry that's done on the core samples is
difficult enough that after we have precipitated silver
chloride, we generally don't have enough to make splits. We
make enough silver chloride for one, perhaps two analyses.
So we don't have in our laboratory a supply of
silver chloride from the ESF samples. To do that would
require processing much more sample than we've got.
And let me make one further point. When we got
into this, what I assumed was that we would measure these
samples and we would see bomb pulse chlorine-36 in all of
those samples. That was my assumption.
Now, if we had made those measurements and
observed those elevated ratios and everything, we wouldn't
be here. No one would be asking questions about precision,
no one would be asking questions about accuracy, no one
would be asking questions about did you shake your samples a
certain way and do you shake your samples a different way.
We have seen a big difference, though, and I think
it's important, but it's going to take time to go through
and resolve those.
So the initial work was not done anticipating this
kind of problem. Had it been done anticipating this kind of
problem, we would have had to spend a whole lot more time to
do the work.
MR. LEVENSON: We're not talking about prior to
May, just the concern. I must say -- let me record a
personal comment, that whoever sets the priorities so that
the paperwork has higher priorities than resolving a problem
as important as this really ought to reassess what they're
doing.
MR. HORNBERGER: I have just a quick follow-up.
You were rudely interrupted when you were talking about your
lab comparisons and I just wanted to know --
MR. CAFFEE: Did I interrupt myself?
MR. HORNBERGER: That was it. I just wanted to
know if Livermore -- have you done inter-lab comparisons
with Purdue?
MR. CAFFEE: You know, not in recent years, but I
think we have.
MS. FABRYKA-MARTIN: One of the first things I did
when I became PI on this project back in 1990 was to do an
inter-lab comparison with results from Rochester, which was
still running then, Livermore, and Purdue. And I think I
sent out a total of four blind samples that all four labs
had done and they did pretty well.
I don't remember the exact numbers, but they were
within two sigma, for sure, of one another and I was
satisfied.
MR. WYMER: How much variation do you find in
total chloride content concentration from various samples
that you've taken?
MR. CAFFEE: For in general or for the validation
sample specific?
MR. WYMER: I want to know whether there's a
factor of two, three or five of chlorine concentration from
one spot to another in the repository.
MR. PETERS: How much does the chloride
concentration vary, say, June, in your samples, from north
to south ramp?
MR. WYMER: Is one saltier than the other?
MS. FABRYKA-MARTIN: Okay. Do you want to
rephrase that so you're talking -- whether or not you're
talking about pore water or total amount of chloride leached
from the sample or a function of --
MR. PETERS: I would answer both.
MR. WYMER: Yes.
MR. PETERS: Answer pore water and then --
MS. FABRYKA-MARTIN: Pore water, it's about -- in
the pore water, in the south ramp, it's about 80 milligrams
per liter, on the average. North ramp, we saw much lower
values, I'd say averaging maybe 20 milligrams per liter,
and, also, along the cross drift, about 20 milligrams per
liter.
As far as chloride leached from the rocks, a very
general trend that I saw with a lot of scatter was that we
generally saw bomb pulse -- the samples that we saw bomb
pulse in were the samples that had the lowest quantities of
chloride leached from the rock, whereas the ones that had
the lowest ratios tend to have higher chloride, and that
would be in terms of we did a one-to-one leach, one kilogram
of rock to one kilogram of water and saw concentrations
anywhere from maybe 0.3 milligrams per liter, which means
0.3 milligrams leached per kilogram of rock, on up towards
maybe an order of magnitude or more higher.
Does that answer the question?
MR. WYMER: Sort of. In your analyses, there was
no normalization with respect to the amount of total
chloride, or was there?
MS. FABRYKA-MARTIN: No. We measure the ratio on
what gets leached out and it's an important point to realize
that we're not trying to maximize amount of chloride leached
from the rock.
In fact, it's just the opposite. We're trying to
minimize how much chloride we leach from the rock, because
we don't --
MR. WYMER: I understand that. It just seemed to
me that if there was four times as much chloride to start
with and you had the same amount of chlorine-36, you might
change your ratio.
MR. PETERS: I think that's what I tried to
convey. June, the concentration in the validation samples
for chloride, what was yours, and then, Mark, I guess, what
was yours?
MS. FABRYKA-MARTIN: It was about 0.3 milligrams
per liter that was leached from the validation samples.
MR. PETERS: I don't mean to put you on the spot.
MR. CAFFEE: Sure. But my recollection, without
having my raw data here, is that it's .8 to 1.5, maybe even
two for a couple -- ppm, so one ppm. We're definitely a
little higher than June's.
MR. GARRICK: I was just curious. I'm not a
chemist, so I can't ask good questions like you've been
getting.
But this technique of measuring for bomb pulse,
that chlorine ratio tracer technique or actual measurement
technique has been around for a long time, has it not? And
there's bore holes all over the Nevada test site, are there
not?
So there must be a lot of experience in doing
this.
MS. FABRYKA-MARTIN: No. What's new here, what's
really unique is the fact that we're leaching -- we're
trying to measure chlorine-36, where there essentially is
not much water, so you're leaching rock.
And here, unlike those other types of sample
types, you really have to watch out for diluting your sample
with salt that's trapped in the fluid inclusions or grain
boundaries or wherever it is. That's what is unique.
I don't know of anyone else who is doing that.
They do it in soils, tons of studies using soils, looking at
in situ chloride in different mineral species, ground
waters, but unsaturated rock, I can't think of anybody else.
MR. GARRICK: So you think that the unsaturated
rock and the uniqueness associated with that makes this a
pretty much one of a kind sampling operation.
What I'm getting at is that with all the
experience that you've had at the Nevada test site and the
bore holes, you must have -- have you -- you must have had
either agreements or disagreements in the past and the
necessity for confirmation or reconfirmation.
I'm just trying to get at if you've had similar
experiences in the past, why can't we attack them the same
way.
MR. CAFFEE: I'll answer that different, actually.
First of all, you mentioned that the technique has been
around for a long time, but while it's been around for a
while, it's not the case that this is a routine technique,
like Argonne-Argonne dating, for example.
If you think about how long Argonne-Argonne dating
has been around, in the first couple decades, it was
probably a pretty painful start, too. So that's the first
point I'd like to make. It's still a difficult measurement.
We're measuring a million atoms of something. So that's not
easy.
The second point I guess I would like to make is
that I think, to the best of my knowledge, the only person
that has leached this kind of rock to get chlorine-36 out
for AMS analysis is June.
It's not the case that the literature is just
totally, totally filled with this kind of thing. There's a
lot of data on in situ produced or cosmic ray produced
chlorine-36. There's a lot of data on chlorine-36 in ground
water. Those are all laboratory techniques that we all know
how to do and we can all do that.
But you won't go open Geochemic and find a whole
lot of articles on this kind of application.
MR. GARRICK: I see.
MR. CAFFEE: So I find this disparity in results
not that surprising, to be honest with you. I mean, I think
it's just the normal process of --
MR. GARRICK: Is this the kind of thing where a
sample could be sent to an independent lab outside the
weapons complex, for example, and --
MS. FABRYKA-MARTIN: I have sent samples to Purdue
to process in the past, with mixed results, because I didn't
define the protocol very well. Some samples came in right
where I expected them. Others, they crushed them too
finely, so they came down a little, not as low as Mark's,
but down lower than expected.
But I would like to point out that I'm not the
only one who applied this technique. What would be a fair
statement is to say Yucca Mountain project PIs have been the
only ones to apply this technique. But I wasn't the first
PI on this and, furthermore, my technicians don't allow me
in the lab really, with good reason probably, and there's
probably, over the last -- this project has been going on --
the chlorine-36 project has probably been going on more than
15 years or about 15, let's say, maybe slightly more and
it's had probably five different technicians on it over the
years that have processed samples and the samples have
always been consistent from one technician age to another,
and that's under two different PIs.
At first, they used to be done at a lab in Tucson,
Hydro Geochem, and then it got moved to where I am now.
MR. GARRICK: That was the basis of my original
question, the process that is employed in the lab to make
the measurements, governed by the same more or less
prescriptive process.
MS. FABRYKA-MARTIN: Yes. That part is true.
MR. GARRICK: And was that true for Purdue?
MS. FABRYKA-MARTIN: I had them write the
procedure that they used and send it to me along with the
results when I really should have gotten in on the very
beginning and looked over what they had proposed to do.
I didn't bring those data with me, but it's still
up in the hundreds, the ratio was up in the hundreds, not
down in the 100 or less.
MR. WYMER: Are you comfortable with the fact that
fines might give you a different ratio than stuff not so
finely crushed?
MS. FABRYKA-MARTIN: Yes, I am.
MR. WYMER: Tell me why.
MS. FABRYKA-MARTIN: Because the finer it gets,
the more likely it is you've broken along grain boundaries
or opened food inclusions or made it --
MR. WYMER: That changes the ratio?
MS. FABRYKA-MARTIN: The chlorine-36 to chloride
ratio simply because then it releases that in situ produced
chlorine-36 that's made by neutron capture on chloride and
include an inclusion source, grain boundary, wherever it
resides, as opposed to what's flowing along the micro
fractures between the grains.
MR. WYMER: I understand.
MR. PETERS: Let me follow-up with a question
here. Have you guys plotted the chlorine-36 to chloride
ratio against -- on the Y axis against on the X axis to
total chloride?
MS. FABRYKA-MARTIN: We did for the Los Alamos
results.
MR. PETERS: Do you get just basically a straight
line?
MR. CAFFEE: Yes, sir. I do.
MR. PETERS: Then what you may, in fact, be
looking at, these high ratios, could very well be simply how
much non-radiogenic chloride you release from the rock and
then the question becomes are you, in fact, measuring any
bomb pulse anywhere, because if all your ratio fluctuations
have to do with how much chloride is there total, which is
15 orders of magnitude more stable chloride than there is
chlorine-36, very small changes in your stable chloride
amount released from the rock could very well be driving
this whole ratio.
So how do you resolve that problem?
MR. CAFFEE: Let me make two comments about that.
First of all, you asked me if we had plotted the chlorine-36
ratio versus the chloride, and I said there was no definable
trend. It was just a straight array. That's plotting
chlorine-36 over chloride versus one over chloride. So
trying to come up with a mixing diagram. That's the first
thing.
The second thing is I think the thing you need to
bear in mind is that there may well be two issues here. The
first issue is that in the Livermore measurements, there's
no bomb pulse chlorine-36 in any of our measurements, and
the bomb pulse chlorine-36 ratio is substantially higher.
It's higher by more than factor of ten than what we -- by a
factor of ten, what we're measuring.
Then there is also a difference in the validation
samples, systematic difference between the Livermore ratios
and the Los Alamos ratios. The Los Alamos ratios are a
factor of two to five, something like that. That
difference, the latter difference that I mentioned could
well be some sort of an effect of diluting the signal with
chloride.
That's possible. We haven't proven that that's
the case or proven it's not the case, but I agree with your
line of reasoning and that's part of our path forward is to
look into that.
We don't see any bomb pulse I don't think can be
explained by chloride dilution, because you would be having
to dilute the chloride by an order -- or the entire chloride
inventory by a lot of chloride and we would pick that up.
We would know that. We would be measuring 20 to 50 or 100
ppm of chloride in the leached sample, and we're not seeing
that.
We're seeing a ppm to two ppm, June is seeing a
couple of ppm. So I think there's two different things that
you need to bear in mind. There is the difference -- there
is the fact that our results are systematically different
and this might have something to do with laboratory
protocols.
But then there is also the fact that we don't see
any chlorine-36 or bomb pulse chlorine-36, and I don't
believe that that can be explained by dilution with dead
chloride.
MR. CAMPBELL: But you're also not seeing modern
chlorine-36.
MR. CAFFEE: Bomb pulse, modern chlorine-36.
MR. CAMPBELL: I mean pre-bomb pulse. If the
ratio has been somewhere between 450 and, say, 1150 for the
last 50,000 years, maybe the last million years, and you're
looking at ratios of 50 to, say, about 150, you're looking
at very old chloride.
So it's not just that you don't see bomb pulse
chlorine-36. What you're seeing is very old chloride
relative to any of the samples that Los Alamos has.
MR. CAFFEE: That's right. If there were no other
data in this world and we only had the Livermore data and I
couldn't do any more experiments, I couldn't look and see at
the stepped release of chloride and I couldn't investigate
these processes, and someone forced me to interpret this, I
would have to say that based on the fact that the modern
input is about 500 and our ratios are less than 200, that
we're seeing decay of chlorine-36.
So we would interpret our data as indicating very,
very old pore water, older than -- comparable to a half-life
of chlorine-36.
Now, I think it's way too early to try to
interpret that data like that, but if that's all I had,
that's the way I would interpret it.
MR. PETERS: But as you kind of alluded to, if you
look at the Los Alamos data on the validation samples, it's
comparable to what you would expect to see for background.
If you go back -- right, June? I mean, the
chlorine-36 to chloride ratios for the Los Alamos validation
samples is in the range of five, six,
700-ten-to-the-minus-15, which is very similar to what she
-- what you were seeing in background throughout the ESF.
Now, granted, they haven't seen anything above
1,200 in those Sundance fault cores yet, and I say yet,
that's key, but --
MS. FABRYKA-MARTIN: I don't think we will.
MR. PETERS: Okay. Fair.
MS. FABRYKA-MARTIN: There's not that much core
left for us to process at Los Alamos. Most of the core has
already been spoken for.
So we may not have a whole bunch more samples
coming from validation bore holes, but the ones we do have,
it's true, they're background. I wouldn't call it bomb
pulse in what we've had come back.
On the other hand, when we did find a bomb pulse,
we had a structural geologist pick our location, saying this
looks like a likely flow path, sample here.
We were very careful to try to sample right along
the fractures, so we would maximize the amount of fracture
surface in our samples, and that's not the case for the bore
holes.
MR. HORNBERGER: Can you -- well, you certainly
have looked to see whether or not the processing is
different at some coarse level. Can you summarize if there
are any coarse differences? Are people looking at different
size fragments, leaching times, are the leaching times
different, anything different sort of at that macroscopic
level?
MS. FABRYKA-MARTIN: He shook his samples for
seven hours and we just let ours stew in the soup pot at
room temperature for a minimum of two days and stir it once
a day.
So it's passive versus an active extraction
procedure, and that's what we're both investigating now,
what is the effect of that on extracting both total chloride
and then, even more importantly, on the chloride to bromide
ratio, which is the indicator of how much of it is coming
from the rock.
MR. PETERS: So have you both looked at the
chloride to bromide ratios?
MS. FABRYKA-MARTIN: We're trying. The problem is
that the leachates are so extremely dilute, that we can both
get good numbers for chloride, but when it comes to bromide,
it's really dicey.
So right now, it looks like what we need to do is
to up the scale of the experiments large enough that we can
take a large enough volume of leachate out at each time in
step to evaporate down and concentrate it.
But the problem we have is, at least at Los
Alamos, is my chemist is about 100 percent Busted Butte
project, which means she only does analyses pretty much as a
favor, because there's not really a lot of funding and this
is a much lower priority than Busted Butte. And so she's
processed -- measured a lot of samples, but it takes a
couple months to get the analyses out.
MR. CAFFEE: Let me agree with pretty much that in
its entirety. One of the things that we do want to do is
measure the bromine in these fractions and one of the things
that we want to do, and we've started, but we haven't
completed the analyses, is leach for two hours, leach for
four hours, leach for six hours, eight hours, maybe go back
and look at fines, I think that's a good idea, too, do all
of these kinds of things.
It takes time to do these kinds of things and
we're working on it and we don't have the results in any
state where we could talk about them today.
Regarding the bromide measurements, I think that's
really important. It's just a hard measurement. It's a
very hard measurement and so we have a new chromatograph and
we're trying to make those measurements, but we just have to
get to the point where we feel confident that they're right.
MR. HORNBERGER: Mark, you mentioned in your
presentation that you had a chlorine-36 peer review panel.
I guess that's new to me.
Can you tell me how many are on it and how many
people are from inside the program and how many people from
outside?
MR. PETERS: It was -- I wouldn't be able to
recount the names of the folks. It was four folks. It was
the DOE initiated external peer review committee, went
through a whole series of these back at that same timeframe,
in pre-VA release timeframe, and this was one of those.
In fact, they -- one of their big pushes was to go
to more of a different sampling approach with a cross drift,
and that was actually implemented.
So we did different ways of sampling for the
features in the cross drift than we did in the ESF as part
of their comments, but they did a full-blown peer review and
that agreed basically with where we were at with the program
at that time, anyway.
MR. WYMER: Any other questions? Bill? Well,
we're pretty much right on schedule. Thank you very much.
It's a very important issue. I hope that it gets resolved
shortly.
MR. GARRICK: The next presentation is on fluid
inclusions.
MR. WYMER: Let's get started here. In light of
the confusion, I think I would just as soon you would
introduce yourselves as you speak.
As I understand it, what we're basically trying to
decide is whether the Yucca Mountain repository is a shower
or a bathtub. Please, proceed. Introduce yourself and your
affiliation.
MR. DUBLYANSKY: I would say Jacuzzi rather than
bathtub.
Gentlemen, my name is Yuri Dublyansky. I
represent the State of Nevada here and, also, I am an
employee of the Russian Academy of Science. I am a senior
scientist in the Institute of Mineral Geology, Geophysics
and Mineralogy.
I am very glad that I have this opportunity to
introduce the fluid inclusion issue for you and the reason I
am so happy, and I even flew all the way from Siberia
yesterday to attend this meeting, the reason is that this
issue, which I believe is very important, exceptionally
important for the Yucca Mountain safety and performance, has
been neglected for quite a few years. That's my personal
opinion.
Also, I want to say the name of fluid inclusion
issue is a little bit misleading. So the real issue is not
the fluid inclusion. The real issue is the real origin of
secondary minerals at Yucca Mountain.
Were they formed by hot water pathway through the
mountain or were they formed by rain water percolating down
through Yucca Mountain, this is the real issue.
And fluid inclusions are just a tool, a very
convenient, very robust tool, which allows you to determine
temperatures at which the minerals will form.
This information, the temperature formation is
very important when you try to identify the origin of
minerals.
Now, I also want to mention that the fluid
inclusion method is not something new. It's a very well
established technique. It's been around for almost a
century. It's widely used in many geological, fields of
geology, like oil exploration, mineral exploration, and
many, many different applications.
As I understand, the ACNW and NRC have not been
exposed to this issue for some reason. So I was asked to
prepare a short overview of the fluid inclusion work done at
Yucca Mountain.
First, I want to make it clear, it's not something
new. This fluid inclusion issue has been around for almost
a decade.
In 1992, the panel of the Academy of Science and
National Research Council related the hydrothermal review
concept which was identified by a DOE scientist as a
potential site suitability issue.
This review was requested by DOE, because DOE
needed to have input to make a decision whether to proceed
with characterization or not.
So even though this panel, Academy of Science
panel discarded this issue, the panel did recommend that
fluid inclusion research needs to be done. It was an
official Academy of Science report on the issue.
As far as I know, the first fluid inclusion data
were published in 1993 by Los Alamos researchers Bish and
Aronson and they studied several site samples from depths of
30 and 130 meters from bore holes and they measured
temperatures, fluid inclusion temperatures well in excess of
100 degrees Centigrade.
While I personally have reason to believe that
those data technically are deficient and the temperatures
are probably not correct, they're unreasonably high, but I
cannot check it, of course.
In 1994, the USGS and Los Alamos researchers
published a more detailed paper on fluid inclusions from the
unsaturated zone at Yucca Mountain, since the tunnel ESF had
not been built by that time, they studied samples from drill
cores.
Well, this paper leaves a little bit mixed
impression. On one hand, it does report fluid inclusion
suitable for thermometry, suitable for determination of
temperatures in core sites from Yucca Mountain, but on the
other hand, this paper does not report any numeric data.
So they also just made a statement that this core
site was formed at a temperature less than 100 degrees,
which doesn't really help, because 20 degrees to 100 degrees
centigrade is basically the whole range of water from cold
water to thermal water which you can expect close to the
earth surface, as understood in hydrogeology.
In 1995, I had the opportunity to collect my first
samples, working for the State of Nevada, from the tunnel,
from the first 300 meters of the ESF which were excavated by
that time, and I did fluid inclusion, preliminary fluid
inclusion research on these samples and reported my finding
to the State of Nevada.
Later in 1996, part of this work was published in
abstracts for two national conferences, Geological Society
of America conference and the American fluid inclusion
conference.
Unfortunately, late in 1995, the State of Nevada
-- the funding for the State of Nevada oversight activity
was cut and during the next two and a half years, no work
was done by the State of Nevada scientists, because just we
didn't have money.
In 1998, several events occurred. First, the
Pan-American conference on fluid inclusion, here in Las
Vegas, the USGS researchers Roder and Wellan went on record
by stating that core site samples which they studied from
ESF do not contain fluid inclusion suitable for thermometry,
suitable for determination of the temperature, and,
therefore, those core sites were formed by rain water
percolating through the mountain.
At the same conference, I presented my data, which
I obtained from basically samples from the same tunnel, and
those data indicated temperature. I did measure it for
inclusion temperatures, have found inclusions which are
suitable and the temperature was up to 85 degrees
Centigrade.
So there was quite a disagreement between two
groups of researchers.
Later, in 1998, the U.S. Nuclear Waste Technical
Review Board completed several reports by the State of
Nevada scientists, and one of those reports was a report on
fluid inclusion.
A consultant to NGGRB, Professor Bob Bodnar, from
Virginia Tech, evaluated this report and he not always --
not only evaluated this report, but he also invited me to
his lab and we spent some two days running samples on his
equipment, and finally he was convinced that the data which
I reported in my '95 report are real and they are not
artifacts.
So after that, the Nuclear Waste Technical Review
Board concluded the fluid inclusions found in mineral
deposits at Yucca Mountain do provide direct evidence of the
vast percents of fluids at elevated temperatures in the
vicinity of the proposed repository. So that was a letter
report written by NGGRB.
In September-October of 1998, I did more detailed
research on fluid inclusions and since, by that time, the
state still did not have money for this research, this part
of my work was funded by the Institute for Energy and
Environmental Research.
So the results were released through a press
conference in Washington, D.C., and after that, 30 copies of
this report were requested by one of the U.S. Congress
committees.
I also want to mention that before releasing this
report, we sent it for external evaluation to three well
known, well established experts on fluid inclusion in
Europe, specifically in Austria, in France and in the U.K.,
and all three experts agreed that the research was done
properly and the quality of work is fine and the conclusions
are probably fine, too.
So although there was some disagreement between
the scientists representing DOE and the State of Nevada,
have eventually led the DOE to initiate, in April 1999, a
verification project on fluid inclusion issue which is
currently underway. Dr. Jean Cline, who led this project,
will probably tell much more about this project in a few
moments.
I won't emphasize, I'll probably make some
correction, but this project was not initiated in response
to the hydrothermal theory proposed by Jerry Szymanski.
It's not correct. I quote from one of the memos of this
committee.
Actually, I started my fluid inclusion research,
just viewing this research as a means of very -- testing the
hypothesis of Jerry Szymanski about hydrothermal activity.
So I wasn't the one who proposed this concept.
And when I reported my data and my interpretation,
this data, both data and interpretation were questioned and
were disputed by the USGS researchers, so that it had a
little disagreement in that.
So DOE must be given credit for initiating the
project which must resolve this controversy and must resolve
the situation where two groups of scientists, which study
samples collected from the same location, report very
conflicting observations and interpretations.
So that's my take on this project.
Now, USGS researchers and State of Nevada
researchers and UNLV people are doing a parallel study
basically on the same samples collected, and as far as I
understand, the temperatures, elevated temperatures of fluid
inclusions, they're getting basically the same temperatures
from our samples. But we still do have disagreement on the
interpretation of these temperatures and this probably will
be the focus of the forthcoming discussion.
In closing remarks, I want to say that as you can
see, this fluid inclusion issue was started probably in
1995, where data was available. Nevertheless, the data have
not been used in the DOE major documents, in the viability
assessment of 1998 and in the draft environmental assessment
statement of 1999.
This leads me to suspect that these data will not
be used in the site recommendation consideration report,
either, which is due later this year.
While it's fairly clear that fluid inclusion
research is not complete and much more needs to be learned
about temperatures, about ages of minerals involved, the
distribution, it is my strong opinion that at this point,
DOE has no evidence which would justify elimination of this
issue from consideration in the TSPA.
Thank you very much.
MR. WYMER: Thank you very much. Are there any
questions on this? That's a very fine introduction to the
problem.
MR. DUBLYANSKY: Just one moment. I have compiled
a list of publications and they are attached to the handouts
which I prepared and if you need them, I can try to compile
the original publications and send them to you.
MR. WYMER: Okay. Thank you. John, do you have
any comments or questions? Thank you very much for the fine
introduction. I think Jean Cline is next, is that right?
Would you give us your affiliation?
MS. CLINE: Sure. I'm Jean Cline. I'm an
Associate Professor at University of Nevada-Las Vegas.
Does anyone have a pointer? Okay. We'll wing it.
That's okay. Could we dim the lights a little bit? I've
got one dark slide. What I'd like to do -- can you hear me,
before I get started? Okay.
What I'd like to do this afternoon is to tell you
about a project that we are doing. What I would like to do
this afternoon is to tell you where we are in this project
that we are now conducting to constrain the movement of
fluid with elevated temperatures through the Yucca Mountain
proposed site.
When I put this proposal together, there were four
questions that I posed and the project is constructed or
designed to answer the following four questions.
First of all, do fluid inclusion assemblages
record the passage of fluids with elevated temperatures into
the Yucca Mountain site. Secondly, if the inclusions are
present, what fluid temperatures do these inclusions
indicate.
Third, if present, when did these fluid incursions
occur, and then, finally, how widespread throughout the
proposed site were these fluid incursions.
The scientific plan that we put together to answer
these questions involves four related studies and I'm going
to quickly tell you what they are and the methods we are
using in these four studies and then I'm going to go through
each of these four a little bit more slowly and tell you
what the results are and where we're at now.
First of all, sampling. The first thing that we
did was collect 155 samples from throughout the ESF and the
ECRB. If you're looking for a handout, there isn't any. I
didn't know there was supposed to be one. I apologize.
Paragenesis study next. This is a critical part
of this study. The idea was to put together a growth
history of each of the samples that we collected and the
idea was that if we could understand how each sample formed,
we could then compare site to site and put together an
overall history for the growth of minerals, secondary
minerals throughout the repository site.
The two main tools that we used to do this were
petrography, mostly using the microscope, and then,
secondly, chemical analyses using the electron microprobe.
Additional tools that we are using include
cathodolominuescence; also, oxygen and carbon isotopes, and
we will probably also do some laser ICPMS analyses to refine
the chemistry a bit.
Third, the fluid inclusion study. Again, the
first critical part was to place the fluid inclusions
observed in each of the samples in the appropriate
paragenetic contacts or growth history of each of the
samples. We also looked at the fluid inclusion petrography
and then we did heating and freezing studies. The heating
studies will tell us about the temperature of the fluids
that were trapped. The freezing studies will tell us about
the composition of the fluids.
The final study is dating. We'll be doing uranium
lead, we're in the process now of doing uranium lead and
uranium series dating, to put some absolute times on these
fluid incursions, and, again, the really critical thing is
to place the samples that we are dating in the appropriate
paragenetic context with respect to the sample mineralogy
and growth history and also the fluid inclusions.
I want to tell you a little bit about the
sampling, first of all. Again, 155 samples from throughout
the ESF and ECRB. The goals were twofold on sampling; first
of all, to collect samples of all of the different types of
secondary minerals that were present and then to get a good
spatial distribution.
We tried to collect samples every 50 or 75 meters.
In some places, the gaps are a little bit larger. That's
because there's no secondary mineralization there.
Moving on, I want to tell you about the
paragenesis study. This is a view of one of our thin
sections. It's about an inch and a half across length-wise
here and what we're looking at is a very thin section of the
rock as we look at it under the microscope.
At the base, what we see in black is some tuff and this
sample grew essentially layer by layer upward or outward
from the tuff. The mineralogy is mostly calcite and
silicate minerals. The blue is epoxy. We needed to use
epoxy to stabilize most of the samples.
So where you see blue within the sample, that
reflects zones of porosity and permeability, and there's a
lot of it.
What we see in this sample is tuff, which is
overgrown by some of the early blockier calcite. There are
some discontinuous layers of silicate minerals, quartz,
opal, additional tuff pieces that fell in and were
encapsulated, bladed calcite that overgrows the earlier
blocky calcite and silicates, and is then overgrown by outer
sparry calcite, which also contains some layers of opal.
This is one of the more complex samples from this
site.
Another section, just to show you there is some
variability. Here we see, again, at the base, some tuff
layers, but in this sample, all we see is bladed calcite.
So this particular sample site did not see all of the events
that produced all of the different minerals at some of the
other sample sites.
A third sample, again, at the base, some of the
blockier, more malsave calcite, a discontinuous layer of
quartz overgrown by bladed calcite, which is overgrown in
places by, again, the sparry, more equant calcite and opal.
Here is some selective dissolution of some of the
bladed calcite.
What I'm trying to show you here is that the
samples are in detail very heterogeneous, but that when we
look from sample site to sample site, we see repetition of
patterns and the goal here, again, is to put together a
growth history for each of these samples and then to link
these samples to compare them from site to site so that we
know how the secondary mineralization formed throughout the
repository.
The second tool that we used, I said,
significantly was the electron microprobe. What I want to
show you next is a probe map of this area right here.
On the left, we have a back scatter electron
image. It reflects atomic number or atomic weight and you
can see there is mostly one color of gray, so we have one
mineral here, it's all calcite.
The black is micro porosity or permeability and
what the permeability or porosity outlines is some our
bladed calcite. So we have bladed calcite overgrown by
blocky sparry calcite and on the right we have a magnesium
map. The bladed calcite is black, indicating very low or no
magnesium. However, it is overgrown by sparry calcite,
which shows very fine detailed oscillatory zoning of
magnesium, interspersed bands of magnesium, varying
magnesium bearing calcite.
It turns out that this magnesium bearing calcite
is one of the more important discoveries that we have made
in terms of helping us put together these growth histories
for these samples.
This magnesium bearing calcite is present in more
than 70 percent of the samples across the repository site.
It is always the outer-most and youngest calcite.
So it's critically important in helping us link
the mineralogy from site to site.
I will come back to this calcite, because I also
is critically important in understanding the age of the
fluid inclusions.
Cathodolominescence is another tool we used. This
figure here is about two millimeters from top to bottom. It
just shows you some detailed oscillatory zoning of calcite
that luminesces. There are bands that luminesce
interspersed with bands that do not luminesce. Luminescence
is probably caused by small amounts of manganese and the
absence of iron.
The important thing is that we look for the
location or the presence of this in individual samples and
then its presence allows us to link, again, samples from
different sites, one to another, and, again, put together
the big picture for the repository site.
This picture is important in helping us place
contextually the fluid inclusions.
Summarizing the paragenesis, we have 155 samples
that are heterogeneous, yet they show consistent textural
and mineralogical patterns.
Importantly, the outer mineral zones, which
reflect the youngest geologic events, are especially
consistent; in particular, the bladed calcite and then the
overgrown sparry magnesium enriched calcite.
These patterns allow samples from different sites
to be related to one another.
What are fluid inclusions? A little bit of
background, for people that aren't familiar with these.
Most minerals precipitate from some sort of fluid
and as they precipitate, there are commonly defects that
occur in the atomic structure of these minerals and these
defects may result in the formation of small holes or
cavities in the minerals.
As the minerals precipitate, they are bathed in
this fluid. So this fluid will fill these cavities or holes
and the mineral may overgrow these holes and seal off these
small packages of fluid, thus creating fluid inclusions.
They are important because they are samples of
some ancient geologic fluid.
Okay. Now, if these fluid inclusions or these
systems are forming at elevated temperatures, then as the
whole system cools down, the fluid is going to contract.
However, the cavity does not change in size.
So if the fluid contracts enough, eventually a
vapor bubble is nucleated and this vapor bubble is
essentially a vacuum.
Now, what we can do to examine these inclusions is
to reverse this process, to try to get at the temperature of
the fluids that were trapped.
What we do is we heat these inclusions up, we
monitor their temperature. As they heat up, the vapor
bubble, if present, gets smaller and smaller. The
temperature at which it disappears is the temperature at
which the inclusions homogenize, and that temperature
approximates the temperature of the fluids that were
trapped.
In lower temperature systems, the cooling may not
be sufficient enough to make the fluid contract enough to
generate a vapor bubble. So lower temperature systems may
contain liquid only inclusions.
These are the two features that we'll be looking
at.
Here are some inclusions from Yucca Mountain.
What we see here, the dark line is the wall of the
inclusion. This is calcite, the mineral calcite. Here is
the wall of the inclusion. The majority of it is filled
with liquid and there's a small vapor bubble.
Here is another inclusion, again, mostly filled
with liquid and a small vapor bubble.
This is what they typically look like, fairly
small vapor bubbles. However, these two phase inclusions,
which really, again, reflect the trapping of higher
temperature fluids are far outnumbered by liquid only
inclusions, which are also shown on this slide.
It's hard for me to see them at this angle. These
would reflect the trapping of lower temperature fluids.
This is a typical data set. We have completed collecting
data from all of our samples. Approximately half of the 155
samples that we collected contained assemblages of two-phase
fluid inclusions.
What we see here are three different assemblages
located in different places in a sample. However, almost
all of the inclusions homogenized over a four degree range
from about 49 to 53 degrees C.
This is extremely tight data. It's probably the
best I've ever seen and it's quite representative of what
we've been able to collect at Yucca Mountain.
By far, the majority of the two phase fluid
inclusions at Yucca Mountain homogenize between 45 and 60
degrees C. There are a couple sample sites in the north
ramp where we obtained higher temperatures. Our
temperatures are as high as 75 degrees.
Others, Yuri Dublyansky and some of the USGS folks
have obtained temperatures as high as 85 degrees, but most
of our data are between 45 and 60 degrees.
Where in the samples are these inclusions? Here,
again, we see a typical crust with earlier calcite
overgrowing the tuff and in this case, the earlier calcite
is overgrown only by the magnesium enriched sparry calcite.
So this sample site really saw two calcite forming events.
This gray line here sort of is the dividing marker
between these two types of calcite. The dark squares here
show the location of the two phase fluid inclusions, again,
that reflect the higher temperature fluids.
Outboard of this line, the only inclusions which
we observed in this magnesium enriched calcite were one
phase liquid only inclusions reflecting passage of lower
temperature fluids.
This pattern is consistent throughout the ESF and
the ECRB. Two phase fluid inclusions are trapped in early
blocky or massive calcite and at the very base are in the
cores of the earliest bladed calcite.
One phase fluid inclusions are trapped in outer
bladed calcite and outer magnesium enriched calcite.
This slide really summarizes those facts. Again,
two phase FIAs, higher temperature fluids are recorded in
the earlier calcite, two phase FIAs are not recorded in the
outer or younger bladed calcite or magnesium bearing
calcite.
The two phase FIAs are very consistently either
present or absent in different mineralogical zones and these
patters allow the relative timing of the elevated fluid
temperatures to be constrained.
Now, what we really want to do is to absolutely
constrain the timing of these elevated fluids, and this is
where we're at right now. Here we're looking at the same
sample again. The two phase FIAs located in this area here
and at the boundary or sort of outboard of this zone of two
phase FIAs, there is, fortunately for us, inner-grown,
intermittent or discontinuous bands of opal, which contains
enough uranium for uranium lead dating.
So what we are now in the process of doing is
dating some of these opal samples to constrain the timing of
this event.
Within the magnesium enriched bad, there is a
second continuous layer of opal and by dating that, we can
determine the timing of the changeover from precipitation of
the underlying calcite and the overlaying calcite, and then
there is an outermost opal, shown here in yellow, which was
deposited synchronous with this outer band of magnesium
enriched opal.
So right now we're in the process of dating these
opal bands. Again, the samples need to be carefully
constrained paragenetically in the context of the sample
mineralogy.
To summarize, our goals for dating are to
constrain the age of the latest magnesium enriched calcite,
which is free of two phase FIAs. In other words, which did
not see the passage of elevated temperature fluids, to
constrain the age of the earlier calcite that does contain
the two phase FIAs, in other words, which saw the passage of
fluids with elevated temperatures, and to determine the most
recent timing of fluid passage with elevated temperatures.
Concerning where we are with respect to project
completion, we are on target for completion and distribution
of reports at the end, about the end of March. We are
currently finalizing the petrography and the paragenesis.
We have completed the fluid inclusion analyses. We are in
the process of doing the dating on some of the other
analyses and we anticipate that they will be completed by
the end of the year.
We anticipate reporting significant results,
including data, at the Geological Society of America meeting
in mid-November.
The final comment that I would like to make is
that in undertaking, as we have been conducting this study,
we have been meeting regularly with scientists from the USGS
and the State of Nevada to discuss our procedures, our data,
what we're doing, how we're doing it.
We have also been meeting with a larger group that
includes people from the NRC, Department of Energy, Nye
County, the Nuclear Waste Technical Review Board and keeping
them apprised of where we are at and what our results are
and the goal here is really to inform anyone who is
interested what we've done, how we've done it, with the hope
that when we are through this project, there will be a broad
understanding of what we've done and consensus on the data,
if not on all the conclusions.
Thank you. I would be happy to answer any
questions.
MR. WYMER: Thank you very much. The former
director of the Oak Ridge National Laboratory, Ivan
Weinberg, used to say there was big science and small
science. This is certainly small science here.
MS. CLINE: Yes.
MR. WYMER: Any questions, John?
MR. GARRICK: No.
MR. WYMER: Do you have a comment over there?
Yes, please.
MR. DUBLYANSKY: Jean, by saying -- well, by kind
of making -- elevated temperature and non-related
temperature, ambient temperature, can you put a numeric
number on that?
MS. CLINE: No. It would be desirable to do so,
but we can't. We have homogenization temperatures as low as
35 degrees C. So we can have two phase fluid inclusions
that were trapped as low as 35 degrees C.
The one phase fluid inclusions, there is nothing
that we can do to get at the temperature of trapping.
People have hypothesized a range of temperatures. I've
heard below 90 degrees, I've heard below 50 degrees, I've
heard below 75 degrees.
It's not -- I don't know how to test that. So
it's hard to say. There are -- I guess I'll leave it go at
that.
In general, I will review the process here. The
idea, again, is that as the system cools down, the fluid
shrinks, and if it shrinks sufficiently, it generates a
vapor bubble.
So those fluids that cool down a lot will generate
a big vapor bubble. Those fluids that cool down a little
bit or a lesser amount will generate a smaller vapor bubble.
Those fluids that cool down and shrink minimally will not
generate a vapor bubble.
But putting a number at those brackets, you can't do it,
because in nature, it's going to vary from location to
location, fluid composition to fluid composition and so on.
I will leave it at that.
MR. DUBLYANSKY: I just wanted to comment on that,
because from your presentation, seemed to be kind of very
clear. We have two phase fluid inclusions, elevated
temperature, we have one phase fluid inclusion, it's low
temperature.
It's not correct, because if you have two phase
fluid inclusion, you have an advantage, you can measure the
temperature. If you have one phase inclusion, you cannot
actually tell the temperature. It may be 30 degrees
Centigrade, it may be 50, it might be 60, but just by some
reason, this shrinkage bubble did not form.
So you should not probably put an equal sign
between one phase fluid inclusion and low temperature fluid.
MS. CLINE: That I would argue with. I think we
can't put a number on it, but in general, we can say that
the lower temperature inclusions are those that don't
generate a vapor bubble and the higher temperature
inclusions do generate vapor bubbles, and we see very, very
clear patterns.
We see certain mineralogical bands which contain
two phase and one phase inclusions and then we see other
mineralogical bands that very consistently contain only one
phase inclusions, and I'm real comfortable saying that there
is a temperature differential that's reflected by the
presence of those, but I can't put a number on it.
MR. DUBLYANSKY: That means there could be this
difference, but it does not necessarily mean that the
temperature was ambient.
MS. CLINE: Absolutely.
MR. DUBLYANSKY: That was the clarification that I
wanted to make.
MR. WYMER: Is it clear that the all the gas in
the bubbles is water vapor?
MS. CLINE: Good question. It depends on your
hypothesis, on what was trapped. If you believe it was
meteoric water, then it probably is a vacuum or just air or
a vacuum essentially by the contraction of meteoric water.
IF you believe that the fluids came from somewhere
else, the source in which those fluids might be transporting
dissolve gases of some sort, and in other systems, it's most
definitely been shown that that can happen, then that vapor
bubble could be something else. It could be carbon dioxide,
it could be a mixture of carbon dioxide and other gases.
There are some tests that can be done. They're
difficult to do and the tests that have been done to try to
distinguish that have not definitively shown things one way
or another.
MR. WYMER: What is the biggest ratio of gas to
liquid that you've seen?
MS. CLINE: We usually -- the call that we've made
is ten percent, ten volume percent or less gas, 90 volume
percent or more liquid.
MR. WYMER: That's the upper limit.
MS. CLINE: Yes.
MR. WYMER: That's a lot of contraction.
MS. CLINE: I should back up. What I talked about
are two types of inclusions, the two phase liquid-vapor
inclusions, the one phase liquid only inclusions. There are
also some vapor only inclusions that are not well
understood. There are not very many of them, but they are
present.
Then there are also some other liquid-plus-vapor
inclusions that have larger vapor bubbles, but these
inclusions tend not to have consistent liquid-vapor ratios
and that makes you suspicious that they formed under some
other circumstance than the ambient conditions at the time.
So we throw those out because they are
inconsistent. They probably formed as a result of leakage
or perhaps what we call necking down when the inclusions
were formed.
We have textures we can use to sort those out.
MR. WYMER: Can you say what the age of the most
recently formed bubbles is?
MS. CLINE: No. That's the data we're waiting on
right now. We have a number of samples that have been
submitted to a lab in Ontario. To date, the opal, they've
been there for a long time. We thought we'd have more
numbers by now. We hope to have them at any time and we
hope to be reporting those at GSA. That's a big question.
MR. WYMER: Yes.
MR. DUBLYANSKY: Can I just add a little bit? To
your previous question about gas inclusions. Yucca Mountain
does contain all gas inclusions. It basically does not
contain visible water. And I tried to study this inclusion
by using random spectrometry, but all I got is a huge --
which indicates luminescence, which is normally interpreted
as the presence of aromatic hydrocarbons there.
Enough indication that that's probably the case,
but this luminescence decay with time, the hydrocarbons
decompose.
But still I was not able to identify any
particular gases. It's a very interesting subject and I
have never seen such inclusion in any other environments.
It's very unique, I would say.
MS. CLINE: One thing that I could add. The
freezing point depression gives us some information on the
composition of the fluids and that freezing point depression
is very small. So it indicates that there's very minimal
salts or minimal gases dissolved in the fluid. Pretty close
to pure water.
MR. DUBLYANSKY: Can we put a number on that?
MS. CLINE: The freezing point depressions were
about half -- I don't know, Nick, can you help me out? Do
you remember what either the freezing -- minus .6 was the
freezing point depression. So about a weight percent NICL
equivalent.
MR. DUBLYANSKY: So it's not quite -- one weight
percent of NICL is not quite fresh water.
MS. CLINE: It's not pure water, but it's close to
pure water.
MR. DUBLYANSKY: It's brackish, I would say, in
terms of hydrogeology.
MR. GARRICK: Do you have an opinion about the
results you might get in terms of whether or not there's a
real safety issue associated with the repository?
What kind of results would give you some concern
about the safety of the repository?
MS. CLINE: I guess I'm hesitant to answer that.
What we see now -- I think everybody agrees who has been
working on this that the fluid temperatures are somewhere in
the neighborhood of 50 degrees C and in one area they may
get as high as 75 or 80 or maybe even 85 degrees C.
What does that mean in terms of engineering the
repository site? I don't know that.
MR. GARRICK: That's a question we have to answer.
We have to answer the so what question and you haven't
answered that.
MS. CLINE: I think part of the answer -- well,
part of what we're doing will help you answer that question,
it's going to be the timing of those 50 degree plus fluids.
We're waiting for these dates on these opals. They're going
to tell us if that happened in the last half a million
years, million years, five million years ago, nine million
years ago. I think that's going to be a big part of the
answer.
MR. GARRICK: What if it's ten million years ago?
MS. CLINE: Well, it's a blink of an eye in
geologic time.
MR. GARRICK: I'm talking about the safety of the
repository. What's it mean?
MS. CLINE: We would have to take the data that we
get from this study and then put together our hypothesis of
where that water came from and until I get the dates, we
can't do that.
If the hot water happened ten million years ago,
there were hot volcanic rocks there ten million years ago.
That's the obvious answer. If the hot water was there a
million years ago, something else was responsible for hot
water being there, and I don't know what that is at this
moment.
I'm willing to wait for the dates before I try to
answer that.
MR. GARRICK: Thank you.
MR. WYMER: Any other questions or comments?
MR. GARRICK: Do we have another presentation?
MR. WYMER: Who is next? Would you introduce
yourself and your affiliation, please? Thank you, Jean.
MR. GARRICK: Thank you.
MR. PETERMAN: My name is Zell Peterman and I'm
with the USGS. I'm currently the Team Chief for the Yucca
Mountain Project Branch Environmental Science Team. We
certainly agree with Yuri's earlier statement that this is
not a fluid inclusion issue, it's a calcite multiple
fracture filling issue, but I have to add to that that fluid
inclusions aren't the only evidence that's going to resolve
this issue.
In fact, we think it's already resolved.
What I would like to do is step back in time a bit
and if somebody will show me how to work this projector, the
computer thing.
The USGS has been studying these fracture
minerals, first, in drill core and then later in ESF since
about 1989 and prior to that, there were some early studies
in the mid '80s of calcite fracture fillings in drill core.
Listed at the bottom here are the people actually
doing the work. Joel Whelan is the person principally in
charge of our fluid inclusion work and the stable isotope
work. Landon Namark and Jim Pacies are doing the isotopic
dating and Bryan Marshall and I guess to some extent myself
are worried more with the isotopic heavy isotope signatures
in these materials.
So let's have a quick look here. Can I move
around here? Is that coming through? What do these things
look like? The fracture minerals occur in fractures and
lithofizal cavities. Calcite and opal are the main
minerals, although there are other minerals present, clay
minerals, zeolites, manganese oxides and probably some
others.
The coatings, as Jean said, range in thickness
from several millimeters to several centimeters. These are
just two examples. The one on the left is an example of a
fracture surface and there is a scale there for reference.
The small divisions are one millimeter.
The one on the right is the floor of a lithofizal
cavity, lithofizal cavities are gas bubbles that form at the
top of the ash flow sheets as the ash flow degasses, and
they're commonly lined with high temperature minerals all
the way around.
Typically, silica polymorphs and alkali feldspar
are the predominant minerals. There are trace minerals of
ohemitites, some garnet has been found, things like that,
but they encrust the whole inside of the lithofizal
cavities.
In contrast, the low temperature minerals, calcite
and opal, are typically on the bottoms of these cavities.
Now, the green coloration is opal, which is
fluorescing under ultraviolet light and it's fluorescing
because it's a rather large uranium content, up to 500 ppm
uranium, typically around 100 to 300 ppm uranium, and this
is the key to the dating work.
This is what we can date. We can't date the
calcite directly because of it's very low uranium content.
Why study these fracture minerals? AS far as
we're concerned, the USGS is concerned, they are the
physical records of long-term infiltration through the UZ.
This is -- I think what Jerry Szymanski refers to as the
USGS rain water hypothesis, and actually I kind of like
that.
Our conclusion after looking at all sorts of data
is that these were formed by downward percolating water.
We can date these things, as I mentioned, by
uranium series, uranium lead and carbon-14, and provide a
history of deposition and, therefore, a history of the
fluids involved in depositing these materials.
The calcite especially also contains an isotopic
record of the source fluids and we look at oxygen, carbon,
strontium and U-234-238 ratios and they contain fluid
inclusions that may yield information on the thermal history
of the rock mass.
From 1990 to 1995, the only thing we had to look at were
core samples and this is an exceptional sample here. And we
tried to do some dating, some mineralogy, some isotopes. Our
eyes were really opened when the ESF was constructed and we
found deposits like this, which never would have survived a
coring process.
So we were really misled by what was available in
only the cores. And the ESF materials are far superb. We
can collect good samples and, again, this green coloration
is fluorescing opal on the tops of these very delicate
calcite crystals that are growing up from the base of a
lithofizal cavity.
So this is the history, that was the core. Core
studies were up to 1995 and in '95 we ramped up our efforts
because of ESF, did a lot of isotopes, mineralogy, fluid
inclusions.
Our early focus was on the history of the
outer-most surfaces, because we were testing a model at that
time, in 1995, that, in post-glacial times, the PTN was
acting as a unit that moved the flow of water laterally
rather than allowing it to come down.
So we were tasked with what is the under stage on
the outer-most surfaces that you can find, the idea being
that we probably wouldn't find anything less than 10,000
years.
A more recent focus has been the long-term
deposition on the thermal history of the UZ, the
compositional evolution of fracture water, and turning our
age information and abundance information into some estimate
of seepage flux.
So what do these things look like in the ESF? And
you will see some of these tomorrow. There are primarily
two major occurrences. There are other minor occurrences,
as cementation in fracture zones, things like that. The
depiction on the left shows a fracture that opens up, and
you will see a lot of these in ESF and you will see that the
deposits are typically on the foot wall side of these
moderately to steeply dipping fractures.
The one on the right is a depiction of a
lithofizal cavity and there you will see that typically the
deposits are on the bottom.
Our interpretation here, and this is not an interpretation
that's agreed to universally, is that this indicates some
sort of film flow moving down these fractures and it's
moving under the force of gravity. So it's staying on the
low sides of the opening.
In contrast with what we see in the UZ are what
you will see in the ESF in the calcite below the water
table, and, again, we're looking at drill core. The calcite
coats all the surfaces of fractures and commonly fills the
fractures.
As I say, we interpret the occurrences as
indicating downward flow along fracture foot walls and
cavity floors. We view this as pretty strong evidence that
those cavities have not been repeatedly hydrologically
saturated.
Jean made these same observations. Calcite and
opal are intimately associated in micro stratographic
relationships. In other words, you can develop the micro
stratigraphy starting with the base, lying on the tuff,
going to the outer surfaces, and, in many case, you can
convince yourself that this is an age progression.
We have data from WT-24 which says that the
average calcite abundance in the rock mass and the crystal
pore member of the Topapah Spring tuff is .24 weight
percent, and I will show you that data in just a minute.
Calcite dominates, as you saw in Jean's slide,
probably less than ten percent, ten percent or less opal and
other minerals. The deposits aren't homogeneously
distributed in ESF and the greatest abundance that we've
measured and another way we've measured is conduct line
surveys and actually stretch a line, a 30 meter line every
100 meters and measure the thickness of the calcite deposits
in fractures and in lithofizal cavities.
And this is an example of the data from WT-24,
which we thought was another way to get an idea, and WT-24
was drilled by the LM-300. So there was a lot of cuttings,
a lot of ream cuttings. If you've seen the holes drilled by
that, and these cuttings were captured for us, integrated
five foot samples and from those five foot samples, we
ground them up, prepared a sub-sample and chemically
analyzed the samples for C02, and then we assumed that all
the C02 as in calcite and that's the way we get the .24
weight percent.
And that's the mean and, to me, this is analogous
to, say, determining the grade of an ore body. So in this
case, the arithmetic mean is the appropriate measure, even
though the distribution of values is highly skewed and looks
almost maybe fractal in nature.
There are many, many openings in the ESF that
don't have secondary minerals, and this is just an example
of one. This is a photo moziac of the tunnel wall over ten
or so meters, 20 meters maybe, and the red coloration
depicts cavities that have secondary minerals and the white
that don't have secondary minerals.
So, again, if these were the result of upwelling
water, I think we have to ask the question why aren't all
the possible depositional sites occupied by calcite.
In terms of the isotopic evidence that favors
descending water, we have carbon isotopes and the youngest
calcites overlap those of the surficial calcrete, and that's
the ultimate source of the calcium.
If you've been out to Yucca Mountain or anywhere
in the desert southwest of the U.S., you will see thick
deposits of calcrete that are ubiquitous. And rain water
comes down and periodically dissolves this and carries it
down fractures.
You can see this virtually anywhere you go. The
oxygen isotopes in the youngest calcites are consistent with
meteoric water heated as it moves down the geo thermal
gradient.
The strontium ratios in the youngest calcite
overlap the values with calcrete, which you'll see in a
minute.
Work at Los Alamos has shown that the UZ calcite
has pronounced negative cerium anomalies. This is not
observed in the saturated zone calcite and cerium anomalies
are small or nonexistent in ground water.
The 234-238 ratios are identical to calcrete, values in
calcrete and runoff, and are much smaller than values
observed in the tertiary volcanics or ground water.
And the conclusion is obvious.
MR. HORNBERGER: Can you give me just a quick
tutorial on the cerium anomaly?
MR. PETERMAN: This is Los Alamos' work and I
think it has to do with the oxidation state, the multiple
oxidation states and the solubility. This is just an
example of the oxygen and carbon isotope analyses that Joe
Whelan has conducted. I should have put the number up
there. There's a lot of measurements and Joe has also
placed the deposits or determined the paragenetic sequence
for the deposits, and, again, these are relative things, but
he can classify things as early, intermediate and late, and
in general, putting the isotopes in that context forms three
discreet groups, but with a lot of scatter.
But if you get enough analyses, you know that
there are clearly three discreet groups there. There is an
early calcite that occurs below the cal layer, I think that
Jean referred to, and it has these low delta 018 values,
which Joe interprets as having formed from water with
elevated temperatures, and he's taken water of minus 12.5
and then just using the fractionation factor, he would guess
that those could have formed from water between 50 and 80
degrees centigrade.
Here is strontium data on calcite from drill core
and at the top there is a histogram. Unfortunately, there
is not an indication of the number of samples, but the
shortest box there would be one analysis and these are --
this is strontium-87-86 values shown as delta 87, which is
just the deviation of the 87-86 from that value for modern
sea water.
So the calcretes have a skewed distribution, but
they peak around between delta value of between four and
five, and you can see the shallow calcites pretty mimic that
distribution and then as you go deeper into the UZ, the
numbers go down and then in the SZ, the numbers are quite
different, the strontium numbers are quite different than
the strontium values in the UZ.
We have data from core water salts, from, I
believe, SD-6, and we see a very systematic change with
depth and what we see is the beginning of a certain amount
of water-rock interaction right around the PTN and then
continuing down.
So we've got a combination of source, plus
water-rock interaction here.
Geo chronology. We've done carbon-14, uranium
series, uranium lead dating, and as I said, our first
emphasis was on the outer-most mineral surfaces and these
three boxes on the left are nested here or correlated. You
can see they each represent different spans of time.
We get carbon-14 ages as young as 16,000 years.
We get uranium series ages that span from very young to the
limit of the method, which is 500,000 years, and then we get
the uranium lead ages that go to 1.8 million years.
It was this relationship that led to the concept
that we're dealing with, very slowly depositing material and
that a given thickness of these things represents a long
amount of time.
So that the challenge here is sampling for dating.
You will see in the next slide that we're looking at one to
four millimeters per million years. Now, we have to
physically sample these with a demo drill, so we're
integrating -- our samples will integrate over a finite
period of time and the results then will be skewed as a
function of the decay constant of the method being used.
And an example would be if you had two layers of
calcite, one that was modern and a subjacent layer that was
a million years old and your sample included both of those
layers, that composite sample would be 50 percent modern
carbon and your age would be, what, 6,000 years, your
determined age, but the real average age would be a half a
million years.
So that's the kind of bias you can get in the age
work in dealing with the shorter half-life systems.
Now, when we go to the uranium lead system, it's a
much longer half-life, so we're getting much closer to the
real mean age of the material sample and the histogram on
the left gives the current distribution of ages we have.
There is this older calcite layer that's
associated with this limpid quartz and some of that has
enough uranium to date and the oldest age we've gotten so
far is ten million years.
Then it progresses up and I think the histogram is
more of a function of how we've sampled what we've
emphasized than it is a statistical distribution of ages.
And this shows the data that have gone into the
interpretation of the growth rate. In the upper right-hand
corner is a cross-section of a sample and, again, the green
fluorescence is opal.
This has opal embedded in it and opal on the
outside. You'll see an age around seven million years at
the base and then 4.5 and 4.3 and I can't even read them all
myself, .14 and .09 at the outer surfaces.
So here is an example of what we call the micro
stratigraphy and in this case, we seem to have it calibrated
with ages.
Right below that, you will see a series of lines
associated with data and these represent different specimens
for which we have these same type of data and what we've
done is just taken the thickness and normalized the
thickness to unites.
So plotted on the Y axis is just relative position
in a crust or deposit and then the slope of that line you
can calculate back and get some estimates of average growth
and those go from 1.3 to 4.1 per million years. So we think
they're very slow growing.
This was verified by some work that was recently
done on what's called the SHRIMP, USGS Stanford SHRIMP, in
Stanford, and this is the high resolution ion mass
spectrometer, where you can actually zap a sample with, say,
a 10 to 20 micron diameter beam, you have a beam of oxygen
ions, and get ages directly without having to go through
sampling or chemistry.
So that other diagram, up at the top there, you will see a
deposit of opal, one of these hemispheric opal deposits,
which is in the outer-most surface and that traverse has
ages ranging from 5.1000 at the outer-most zapped point to
530,000, but with a huge uncertainty. Anyway, the graph
below that plots that data and, again, the growth rate there
for that opal using those numbers is .72 millimeters per
million years.
So this substantiates our contention that these
are very slow growing deposits.
Fluid inclusions, Jean and Yuri have already
covered this. Joe sees the same thing that everybody else
does, single phase liquid filled inclusions, single phase
gas filled inclusions, two phase with variable liquid gas
ratios, and then the two phase was small, but consistent
vapor-liquid ratios.
And with certain assumptions, these may provide
estimates of depositional temperatures.
I think it's appropriate to comment here that when
the major fluid inclusion thrust started, and I think Jean
would agree that there was a lot of discussion on whether
calcite was a suitable host for these fluid inclusions,
whether calcite could be relied upon, because it was known
from other studies that you look at the mineral crosswise
and you're going to do something to the fluid inclusion.
So there was a lot of discussion and I guess being
a skeptic, I'm still somewhat skeptical, but I'm willing to
be proven wrong.
Anyway, as Jean said, we find also 50 percent
inclusions contain deposits, contain fluid inclusions 40 to
80 degrees C. Many of these are in the earliest calcite. A
few appear to be in the intermediate stage. None have been
found in the latest calcite.
We think the fluid inclusion assembly is
consistent with calcite formation under vados conditions,
but at slightly elevated temperatures. In other words,
unsaturated conditions. Yuri would say that these all
formed in the sat -- that there was saturation, that these
fractures were filled with water. We don't agree with that.
MR. HORNBERGER: But you would still have to have,
as Jean said, a model, a conceptual model for getting the
elevated temperatures.
MR. PETERMAN: That's true, right. Absolutely.
If we can believe the elevated temperatures. I think one
has to ask that question first and foremost, and then we
have to ask how could you get those elevated temperatures.
We know that you can, you know, 12.7 million years
and probably a few decades after that, things were very hot.
We find evidence fumerolic deposits at the top of the
Topapah Spring that are 12.7 million years old, no doubt
about it. Just like the Valley of 10,000 Smokes, the water
was getting very hot as it penetrated a little bit and the
tuffs cooled and crystallized from the top down and there
was water circulating and coming back out as very vigorous
hot springs and steam vents and all that.
There is no doubt about that whatsoever. Then the
question is how long did it take to cool the tuffs, say, to
50 degrees. I don't think we have a good handle on that.
There is a Timer Mountain Caldera, which you
referred to -- it's usually quoted about 10.5 million years,
called the Timber Mountain Event. Brian Marshall has done
some thermal modeling and shows that at Yucca Mountain, 20
kilometers away from a possible buried pluton, there is a
thermal pulse that could hit Yucca Mountain about eight
million years ago and then that has to decay down.
Now, it's a very simple model, it's conduction
only, there's no advection and all that. It's something
that needs to be pursued.
MR. WYMER: We are starting to push our time a
little.
MR. PETERMAN: Okay. I'm going to finish real
quick. This is just another example of distribution of
fluid inclusions that Joe Whelan did. This is from one
little teeny chip, 320 measurements. He's got the patience
of Job, 54 degrees. There are some flyers out there, up to
80 degrees, 54 degrees, excluding those, standard deviation
of three.
This bothers me a bit. Two standard deviations of
six, total range of 12 million years. If we can measure
these things to better than a degree, why do we get this
dispersion. It's telling me there are some other variables
in here we don't fully understand.
This is the USGS data now plotted against distance
from the north portal. Those higher temperature values that
Jean referred to in the north ramp around 80 to 90 degrees.
Again, that's just a map showing the USGS data.
Our attempt to constrain ages, this was asked and, again, so
far, all we've done is try to sample opal that's immediately
above a zone that contains fluid inclusions.
We have ten ages now, our youngest age is 1.9
million. All of the others fall between eight and nine
million, here is one that's seven, okay, 6.5 or seven.
Again, they only provide a minimum age and the maximum age
is controlled by the tuff.
So I would say on the right, the fluid inclusions
are between 6.5 and 12.7 million years old. On the left,
they're between eight and 12.7 million years old, and this
one sample has this bounding opal at 1.9.
So as I say, I think we have ten numbers now and
this is something that both UNLV and the USGS is pursuing
vigorously.
These are our conclusions. We have large and
comprehensive data that shows that low temperature fracture
minerals form from meteoric water percolating downward
through the rock mass during the last ten million years or
longer.
I think the fluid inclusions may provide very
interesting information on the thermal history of the rock
mass and I think that's something that should be pursued as
best we can.
So that's it.
MR. WYMER: Thank you very much. Are there
questions? Surely our geochemist must have a question.
MR. DUBLYANSKY: I have a question. Do you have
conceptual model for high temperature calcite formed in the
vados zone, how much did it happen? I didn't quite
understand your answer.
MR. PETERMAN: Our contention is that those
temperatures are real and I still think we have to be a
little bit skeptical, because of uncertainties, assumptions
and all that, but those temperatures are real, then that
means the rock had to be that hot to heat the downward
percolating water.
Now, these could be -- it doesn't just have to be
done by the cooling of the tuffs. As I say, there is
certainly a potential of an eight million year thermal
coming from the buried pluton in the Timber Mountain
Caldera.
There are other ways to move heat into the upper
crust. One way is detachment faulting, which is well known.
You bring hot rocks up along shallow dipping normal faults
below cool rocks and you have a perturbation of the
geotherm.
And we know that detachment faults are not at all
uncommon in southern Nevada. There's a whopper of one just
across Crater Flat over at Bear Mountain that did exactly
that and that area over there, based on geo chronology,
there was activity as young as eight million years.
So I think there are certainly ways to get heat
into the unsaturated zone without pumping up hot water.
MR. WYMER: Well, John Garrick always likes to
drive to the very practical end of things, so what does this
all mean with respect to Yucca Mountain.
I think I understand what each of you concluded,
but is there any of the three of you that believe that there
is a chance that hydro thermal water is going to come up and
fill the cavities? That's your position, that that's a
possibility.
So of the three of you, there's -- you want to
vote?
MR. PETERMAN: I think we have to leave it up to
the scientific community to evaluate these results and make
their own conclusions. We've already made ours.
MR. WYMER: How far off are we of having these
answers in time?
MR. PETERMAN: I would say less than a year.
MR. WYMER: Less than a year. You have another
presentation? I'm sorry, Yuri.
MR. DUBLYANSKY: Just I will be trying to
summarize what can be hypothesized about the sources of
those fluids and the origin of minerals from the data which
are available now.
So if you have more data or some new data that
will show up, we will probably incorporate them into the
model.
But I base my presentation on what was done by
USGS at least what was available to me and on my new fluid
inclusion research was done just recently during this year.
So I'm not sure about this idea about heating the
rock due to faulting or thermal process. The calculation
done for Yucca Mountain and as soon as I have this more
formalized model, I will be happy to make an assessment of
that.
We did, however, estimate the time required for
cooling of tuffs and the age of the bedrock is about 12.7
million years, and our very conservative estimates show that
the cooling would require a maximum of about 100,000 years.
So essentially we attribute the formation of this
elevated temperature to the cooling of tuff, we have to have
the age of this calcite to be close to this 12.7 million,
12.8, but it cannot be -- it cannot last for millions of
years.
Then we have this very well known Timber Mountain
Caldera hydrothermal, which is dated from 11.5 to ten
million years ago, and this work was extensively studied and
dated like that. So we have another time marker here. And
then if we see that our sample or our elevated temperature
calcite was formed at the time after that, I cannot see of
any other explanations than to attribute it to the thermal
activity, hydrothermal activity, because again, I repeat, I
cannot see how it can conductively heat the rock to such a
high temperature.
Also, we will continue with further -- we not only
have to heat it, but also if we find all the data, we have
to maintain this temperature for very long periods of time,
and I will come to this later.
From the data which I had, I didn't have this new
data that they measured ages of the quartz at ten million
years, but these preliminary data indicate the age of the
oldest -- by that, I mean the oldest ages measured from the
Yucca Mountain samples. They were about nine million years
old.
So they're still somewhat younger than the Timber Mountain
Caldera hydrothermal, and this new age is also between ten
and nine million years.
So I think this makes -- this shows that the
minerals that we're talking about, they are younger than --
probably younger than Timber Mountain Caldera, but also they
are definitely younger than the bedrock tuff, and this is
the quote from one of the USGS reports and they seem to be
aware about that.
MR. HORNBERGER: Yuri, you disagree that those
ages represent a minimum age then.
MR. DUBLYANSKY: Well, minimum age, as far as I
understand, talking about uranium series dating, which are
more short-lived isotopes.
Would you say that uranium lead ages also provide
minimum estimates of that, of ages?
MR. PETERMAN: The ten million years is on the cal
simulator.
MR. DUBLYANSKY: Right. The question was --
MR. HORNBERGER: But I understood Zell's point to
be that you're sampling an interval and --
MR. PETERMAN: We're sampling an interval, but
because of the long decay constant for the uranium, we're
still getting an average age, but it's closer to the real
age of that material.
MR. DUBLYANSKY: On these graphs, I plot the
thermal reconstruction of the Timber Mountain Event done by
Bish and Aronson, these red arrows, and this work was done
based on the transition between clay species.
And the red rectangle shows the temperature, which
was obtained from the ESF samples.
You can see it's quite different, 85-90 degrees
Centigrade at Yucca Mountain, just ten degrees short of
boiling at this altitude. If you just assume normal thermal
gradient, conductive thermal gradient, which should be
operational in the vados zone, you will have here a gradient
of about 200 degrees Centigrade per kilometer, which I don't
think is reasonable.
So I don't think by conductivity they can raise
the temperature to 90 degrees at depths of about 50 or 30 or
100 degrees from the surface and keep this temperature for a
long time and I don't see how can we do that without melting
the rock.
Now, let's discuss a little bit ages. First, we
have this time marker -- well, mostly, the minerals which
can be dated at Yucca Mountain is silica. We only can date
the latest calcites which can be dated by uranium series
ages, but all calcite cannot be dated because it doesn't
seem to be old enough.
So we have to use some indirect methods,
particularly in those samples that do not contain silica
phases.
However, it is well known or established at Yucca
Mountain that opal is always younger than ten million years,
or probably eight million years, and the diagram which Zell
was showing, it's clearly demonstrated that.
When you talk about opal, you are talking about
something between eight million years and probably a 100,000
years, and, again, I refer to the work done by USGS.
So if we see fluid inclusions associated with this
late opal, we have to assume that this calcite is also
young. This is one example of the situation.
This is calcite and this -- calcite, opal, which
is typical young opal which occurs normally in the upper
part of the samples, and this is one of the fluid inclusions
with a gas bubble here.
This is only one inclusion from a group of
inclusions which can provide quite reliable temperatures.
So in this case, we have to accept that this
calcite cannot be older than eight million years.
Here is another example and it's a very
interesting sample. Again, we have opal in the crust of
calcite, which is about one and a half centimeter. One of
the opal from the samples collected from this area --
actually, there was extensive dating of these samples and
the ages obtained range from six million down to 300,000
years or something like that. Opal from the samples
collected from those cavities.
Again, if we accept this rate of deposition which
was determined by USGS, which is from one to four millimeter
per million years, we have to assume that the time required
for generating this crust would have been at least between
four and ten million years.
Each millimeter of this calcite requires about a
million years to grow. It's quite a long time to form that.
So what I did, I analyzed calcite layer by layer,
above the opal and from outside layers, and here are the
temperatures.
So basically this part probably are secondary
inclusion, but those are very consistent temperatures, 50 to
52 degrees Centigrade, and these temperatures just
persistent through the all the crust.
Again, it's a little bit -- well, it isn't
contradiction, which Jean was showing, that fluid occurs
only in the bottom. These particular samples, you can see
fluid inclusions throughout the crust.
MS. CLINE: You can't equate position necessarily
to age. I guess what I'm saying is that I don't agree 100
percent. You can't just measure some thickness, attribute
some number of years. You can have a whole crust that grew
ten million years ago. You can have a whole crust that grew
a million years ago.
MR. DUBLYANSKY: Exactly that is my point, but I
am not very comfortable with this rate of one millimeter or
four millimeter per million year. I just kind of
exaggerate, but still my point is here in this crust, we
have consistent temperatures throughout the crust and if
these rates are correct, we have to assume like eight
million years timeframe of this growth.
I'm not saying that that's what was happening.
I'm just showing some kind of problems with that. But,
again, these temperatures are very consistent and is present
in all calcite. This calcite looks to me very typical
bladed calcite.
The next method which we can use is to use stable
isotope, like Zell was suggesting, and this is a compilation
of data. Well, it's kind of illustration of data which is
represented in the one of the USGS reports.
Indeed, this report says that early calcite,
probably old calcite almost always have this heavy carbon
and it's light in oxygen and late calcite almost always have
the reverse, light carbon and heavy oxygen.
Late calcite form will define between minus five
and minus eight per mil and this calcite generally
represents the age distribution over the last several
hundred thousand years. That is according to the work by
USGS.
So if we have calcite which have these values, we
probably, again, if we accept this idea of USGS, we have to
accept that we are talking about calcite over the age of a
few hundred thousand years.
So here is one of my samples which I studied.
This calcite does not contain opal, so it cannot be dated,
but it does contain fluoride, not a very typical mineral in
water, and it consists of three zones; base zone, granular
zone, and then blocky calcite.
So I did a very detailed and very careful isotopic
study on this calcite, actually the same thing just turned
90 degrees clockwise.
I used the in situ laser ablation stable isotopic
analysis and with a spatial resolution about 300 microns for
each spot.
Some of this delta C-13 stays positive for the
most part of the crust and the outer part, it drops
dramatically to the values of minus six to minus eight,
which are the typical values which were reported as being
representative of the calcite with the age of on the order
of a few hundred thousand years.
So this essentially carbon oxygen distribution
from this particular sample, one sample, essentially mimics
what was shown by USGS. Again, we have this late calcite
with consistently light carbon and heavy oxygen.
So again, if we accept this USGS interpretation,
we have to assume that this calcite was formed less than
probably 200,000 years ago.
Here are the results. Again, we have fluid
inclusions through all the crusts from top to bottom and
this early calcite, heavy carbon calcite, shows a little bit
more high temperature and this late calcite has a little bit
cooler temperature, but still the thermal temperature is 40
to 46 degrees, 50 to 52 degrees.
So in this situation, we have isotopically light
calcite, which is probably formed at early -- probably young
and it does contain fluid inclusion and in this case, again,
we have fluid inclusion present throughout the crust.
So my point is that at this point, at this stage,
we cannot claim that all fluid inclusions or all calcite
contain elevated temperature. We cannot claim that this
calcite is related to the cooling of tuffs because the age
data does not allow us to tell that, and I think the only
interpretation of that is that this calcite was formed by
fluids with elevated temperature within the mountain.
Thanks.
MR. WYMER: Thank you. Questions?
MR. PETERMAN: I just have a comment. If you look
at page 12 on my handout, you will see that many, many
hundreds of carbon and isotope analyses, they form a very
broad trend and within each group, there is -- maybe it's
not 12. It's the one that has the carbon versus oxygen.
There it is.
There's a huge amount of scatter there and other
than saying there is a real trend, I don't see how you can
use that data, except in the very earliest calcite, which is
below the base cal simulator, which has those anomalies or
very light oxygen values.
I don't see any way how you can use that cluster
of data as a chronometer at all. It's just way too much
scatter.
MR. DUBLYANSKY: My answer will be, first, that
this graph which you represent here on your handout -- I
just remembered the graph from your presentation, which
brackets the temperature of 50 to 80 degrees Centigrade and
those brackets are around the red dots, which are heavy in
carbon and light in oxygen.
It's just not correct, because I just have shown
you that temperature 50 degrees Centigrade and 55 degrees
Centigrade can be associated with calcite which should be on
this blue.
MR. PETERMAN: But you had no age information to
constrain that statement whatsoever.
MR. DUBLYANSKY: That's exactly, but the statement
which you made in your report, they have no bearing on age.
You just refer signature and age. Always, when you report
stable isotopic values of this and carbon is minus five to
minus eight.
MR. PETERMAN: Joe's depiction there is based upon
petrographic delineation of the paragenetic sequence.
That's his categorization.
Any one specimen, there may be age controls, but
he just put together the paragenetic sequence and then he's
put the carbon and oxygen isotopes in that framework.
MR. DUBLYANSKY: Absolutely, but I also have a
paragenetic sequence in my sample and I just have shown it
to you.
MR. PETERMAN: But you had no age information.
MR. DUBLYANSKY: Indeed, I don't have age
information, but I do have indication that -- at least I am
using your information and your work, actually I quote this
in my report, that -- let me just quote you.
MR. PETERMAN: It's not going to do me any good.
I certainly can't remember the paper quotes at this point in
time. But there are typically a lot of things that are
taken out of context.
MR. DUBLYANSKY: Well, this work is based only
stable isotopes and it summarizes stable isotope work and
age dating work.
So I'm just using your information.
MR. PETERMAN: The same diagram is published
somewhere in another report and I would suggest maybe you
use that distribution of value.
MR. DUBLYANSKY: I didn't understand your comment.
MR. PETERMAN: I don't know what report that is.
It may have been 1992?
MR. DUBLYANSKY: No. This is the report, ages and
origin of subsurface calcite, and what I did is I just took
date from your table and quoted them. That's all I did.
MR. PETERMAN: That's fine. That's a general
trend. But if you put the uncertainty on that trend, it's
huge.
MR. HORNBERGER: I think Zell was just saying that
you can't invert that trend, because if you look at his
dots, the 13 on the early calcite goes everywhere from plus
ten to minus six. It's not very well constrained. It's a
trend, but you can't use it as a geo thermometer.
MR. DUBLYANSKY: I am not intending to use it as a
geo thermometer.
MR. HORNBERGER: Or a geo chronometer, sorry.
MR. DUBLYANSKY: Or geo chronometer, too. What I
want to show, we have to have some handle on the -- well,
I'll put it a different way. We probably cannot date this
calcite because it cannot be dated with the uranium lead
methods. So should we just throw away the data, fluid
inclusion data, which we obtained on this calcite? I don't
think we should do that.
So I am using this stable isotope data as as proxy
of the ages, again, based on the work done elsewhere by
USGS.
I understand that that it's not a perfect method
and I will not claim that. But at least we cannot claim, by
the same token, that this calcite is old.
MS. CLINE: Do you have paragenetic data that show
that that particular calcite that forms the outer band in
that sample is consistently present and is consistently a
young calcite throughout the repository site?
MR. DUBLYANSKY: No, I don't, because it's blocky
calcite. It is present -- well, it could be present in many
samples. There's a granular calcite in the middle, which I
was showing it's not very common Yucca Mountain calcite at
all, also it contains fluorides, which also not all samples
are -- not all samples contain.
So I think paragenesis also should be variable
from place to place in Yucca Mountain. For instance,
fluoride, we have found that fluoride is mostly associated
with samples that are collected close to the fault lines.
MS. CLINE: Close to the fault lines?
MR. DUBLYANSKY: Right, close to the major fault
lines and we have found fluoride in many, many samples, in
much more samples that we expected to find them.
No, I cannot parallel this particular calcite as
paragenesis and that's why I'm using -- I am trying to use
stable isotope report to get a handle on where I can place
this calcite.
MS. CLINE: I would just say that in the work we
have done on all the samples where we see the fluoride, it
is in an older part of the sample. We have not seen
fluorite anywhere we can constrain the fluoride as being
part of the younger event, either the later belated event or
the magnesium enriched calcite. It's just not there.
MR. DUBLYANSKY: Yes, but I don't think you have
an age constraint on the calcite either.
MS. CLINE: This is relative age.
MR. DUBLYANSKY: Relative age. In terms of
relative age, well, this fluorite definitely is present in
this zone and the outer zone of calcite, and here you can
see fluorite just protrudes into the surface of calcite.
It's a common calcite and fluorite. Again, basically, it's
one way of addressing this issue, to calculate the
thermodynamics of the calcite-fluorite system and that's
what we are doing right now.
MR. WYMER: According to my schedule, we're over
with our break now. Is there one last burning question or
comment? It's a very interesting discussion. Is there any
final thing that one of you feels constrained to say?
If not, well, thank you very much. It's an
interesting discussion. Let's take a break.
MR. GARRICK: Yes. Thank you. Before you break,
I want to advise you of what we're going to do. There's two
things remaining to be done.
One is to prepare the committee for the tour
tomorrow and the other is simply to do some homework in
preparation for future meetings. I don't think we need the
court reporter for the rest of the day. So I'm getting a
favorable head nod from the staff, so you are excused, as we
adjourn for the break.
[Whereupon, the meeting was concluded.]
Page Last Reviewed/Updated Monday, October 02, 2017
Page Last Reviewed/Updated Monday, October 02, 2017