122nd Advisory Committee on Nuclear Waste (ACNW) Meeting, October 18, 2000
UNITED STATES
NUCLEAR REGULATORY COMMISSION
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ADVISORY COMMITTEE ON NUCLEAR WASTE
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122nd ACNW MEETING
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Room T2-B3
Two White Flint North
11545 Rockville Pike
Rockville, Maryland
Wednesday, October 18, 2000
The Committee met, pursuant to notice, at 8:30
a.m.. MEMBERS PRESENT:
B. John Garrick, Chairman
George W. Hornberger, Vice Chairman
Raymond G. Wymer, ACNW Member
Milton N. Levenson, ACNW Member
ALSO PRESENT:
Amarjit Singh, ACRS/ACNW Staff
Howard J. Larson, ACRS/ACNW Staff
Lynn Deering, ACNW Staff
Richard K. Major, ACNW Staff
Martin J. Steindler, ACRS Consultant
William J. Hinze, ACRS Consultant
Paul G. Shewmon, ACRS Consultant
Maury Morgenstein, Geoscience Management Institute, Inc.
Don Shettel, Geoscience Management Institute, Inc.
Robert W. Staehle, Adjunct Professor, University of
Minnesota
Aaron Barkatt, Professor, Catholic University
April Pulvirenti, Catholic University
Geoffrey A. Gorman, Dominion Engineering, Inc.
Chuck Marks, Dominion Engineering, Inc.
Gustauvo Cragnolino, Center for Nuclear Waste
Stephanie Bush-Goddard, Office of Regulatory Analysis,
Nuclear Materials Safety and Safeguards, NRC
Jim Lieberman, Office of General Counsel, NRC
Paul Genoa, Nuclear Energy Institute
Michael Webb, Office of Nuclear Materials Safety and
Safeguards, NRC
Allen Howe, Office of Nuclear Materials Safety and
Safeguards, NRC
Bret Leslie, Office of Nuclear Materials Safety and
Safeguards, NRC
Tae Ahn, Office of Nuclear Materials Safety and Safeguards,
NRC
John T. Larkins, Executive Director, ACRS/ACNW
Andrew C. Campbell, ACRS Staff [via speakerphone]. P R O C E E D I N G S
[8:32 a.m.]
DR. GARRICK: Good morning. Our meeting will now
come to order.
This is the second day of the 122nd 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.
We also want to recognize our consultants today,
Drs. Steindler, Hinze and Shewmon.
This entire meeting will be open to the public.
Today, the committee will discuss recent tests to
explore the specific aspects of the corrosion resistance of
alloy-22 material. We're going to hear a presentation from
the staff on its rulemaking plan addressing the entombment
option for power reactors and hear comments from consultants
and members on recent relevant activities and continue our
discussion on planned activities, including the entombment
option for decommissioning power reactors, and letter and
report preparation.
Amarjit Singh is the designated Federal official
for the initial portion of today's meeting. Andy Campbell
was supposed to be in that capacity. He is home recovering
from a back problem. I think we will be connected in with
him by telephone. I think that I have his number here
somewhere, if somebody can do that. He's standing by,
expecting that.
MR. SINGH: They're on.
DR. HORNBERGER: He went to get a telephone.
DR. GARRICK: I see. This meeting is being
conducted, as usual, in accordance with the provisions of
the Federal Advisory Committee Act. We've received no
written statements from members of the public regarding
today's session. However, should anyone wish to address the
committee, you can do so by making your wishes known to one
of the committee staff.
As usual, it is requested that each speaker use
one of the microphones, identify themselves, and speak with
clarity and volume so that you can be heard.
We have a lot of material to cover today. This is
a very important topic, as you all know. We have a lead
member on the committee that's been our cognizant person on
this topic, and that's Ray Wymer. I will ask him to take
over and lead the discussions.
DR. WYMER: Thanks, John. It finally has
happened. Chemistry has finally reared its ugly head. As
the few, the proud chemists among us knew, it had to happen
sooner or later.
DR. GARRICK: This is your day.
DR. HORNBERGER: Make the most of it.
DR. WYMER: It may never happen again. But the
importance that we attach to this topic, as indicated by the
amount of time that's devoted to it, we're going to be on
this until noon, which will give us ample opportunity for a
lot of good discussion, I hope, from anybody and everybody
who wants to comment on it.
This morning we have some formal presentations by
several consultants that were brought in specifically for
this purpose. As you all know, the issue of the corrosion
resistance of the C22 alloy, which is the outer layer of the
waste container for the bulk of the waste that will be in
the Yucca Mountain repository, if we have one, is a central
issue.
And within that issue, one of the central issues
is whether or not the conditions that have been studied so
far that have shown rather severe corrosion attack on this
alloy are realistic conditions within the repository
environment itself, and I hope we'll hear something about
that.
We have Bill Hinze here, who will be able to give
us a little insight into some of the geology that will have
a bearing on this.
So we'll start out by -- I'll introduce Maury
Morgenstein, who will then introduce the subsequent speakers
for the rest of the morning. Take it from there, Maury.
MR. MORGENSTEIN: Thank you. My name is Maury
Morgenstein. I want to briefly go over who we are.
Essentially, we're working for the State of Nevada. It's a
team approach.
We have essentially three tasks that we're working
on. We're going to report to you today on one of those
tasks, which is the C22 oversight assessment.
I'm not going to go through reading everyone's
name.
Our preliminary scoping studies on C-22, as
oversight, should not be confused with site characterization
activities. This is strictly oversight and I wanted to
underline that, because there is a big difference between
how one proceeds.
We have three presentations today. The first is
on natural lead and mercury values at Yucca Mountain, the
second on our scoping experiments, and the third on
essentially the waste package environment and waste package
concepts.
We will start out with Don Shettel, who is sitting
next to me here, with our first presentation.
The main issue of this morning and the
environmental assessment of lead and mercury, and I want to
start out here and stress the fact that we are only talking
about lead and mercury in this particular case.
There is a host of transition metals, other trace
elements that are important in our overall discussions
concerning C-22 in the natural environment. We are going to
only concentrate on two of these at this point in time.
We're going to present to you information on fault
and fracture carbonates and silicates that form at the
surface of the ground as evaporates, that form in fault
zones, such as trench-14, and we're going to take a look at
the hydro geochemistry data available for the Yucca Mountain
area, and the data on hard rock, whole rock tufts in the
area.
So there are three different activities dealing
with chem.
For the first, this is a -- and I'm going to turn
this in a minute so, actually, we can look at it
stratographically -- a shot, a stratographic run for
mercury, for core hole, 3D, from Nye County. It's a Nye
County core, Nye County early warning drilling project. And
I want to show you the distribution of mercury in the tufts
and sediments from the core.
At around 500 feet below surface, we have a
uranium deposit in this particular core and that was the
purpose behind our activity here. These data were not
developed for C-22 project. We were looking at mercury.
You will note that there is a marked peak, mercury
peak associated with essentially the uranium peak and it's
probably a uranium roll front hydrothermal oriented. It's
not a very strange thing. We see these elsewhere in Yucca
Mountain area and they're probably related to normal gold
type mineralization that we see in Nevada, low yield. In
this case, we just don't have a lot of gold.
The point is here, we do get some reasonably high
mercury values. That's running about 199 PPM. And they are
associated with unique deposits, but at the same time,
there's a general background.
In the same hole, we take a look at lead, and,
again I'm going to go stratographic. I'm sorry. Turn that
so we can look stratographically.
DR. HORNBERGER: Where did that deposit occur in
the section, in the stratographic section, the uranium?
MR. MORGENSTEIN: The uranium deposit?
DR. HORNBERGER: Yes.
MR. MORGENSTEIN: That's in the tuft.
DR. HORNBERGER: It is in the tuft.
MR. MORGENSTEIN: It's in the tuft, just above the
sediment horizon.
We have a discontinuous data section here on lead.
I apologize, but, again, our purpose was not to look at lead
in this case and we had already used up the samples for
other purposes in the uranium area.
But the point I would like to make here is that
there's essentially no pattern on lead. It's all over the
place. There's a large number of samples that are below
detection limit, but at the same time, we have samples, for
example, at the surface with eight PPM and at depths with
six or seven. So there's no pattern at all associated with
lead.
We do see, in this particular hole, when we look
at the uranium section, we do see galena, which is a lead
sulfide. So there is some mineralization, lead
mineralization coming along with the uranium and it doesn't
show on this particular analysis.
But at the same time, we don't think, from our
other looks in the literature, we don't think that the
sulfide type deposits have exorbitant lead concentrations in
them. We see, most of the time, just normal background.
In fact, I will show you a little bit later the
tufts not associated with sulfide enrichment seem to have
higher values of lead than those associated with sulfide.
I'd like to transfer our attention to the surficial
sediments, the authogenics, those that are formed by
essentially precipitation, and we have -- this shows
minimum/maximum values, looking at carbonate, silicate
veins, fracture fillings, on other words, looking at
calcretes, which are soil horizon evaporates, and looking at
rhizoliths, which are also up in the soil horizon.
And the point I would like to make here is that we
have fairly significant lead concentrations -- this is only
lead that we're looking at right now -- running from a
couple of PPM to about 150 PPM in some cases, and this shows
around 64-65 PPM for trench-14A.
This is broken down into silicate and carbonate
fractions. This work is done by the USGS.
In the same paper, they looked at isotope ratios,
lead isotope ratios, in an attempt to source the formation
of the carbonates and silicates in the veins in trench-14 to
address the question of whether or not we're looking at
meteoric water, down-flow water, or something that was
up-welling.
And it was very clear from the isotope ratios that
this is meteoric water origin deposits. This is a down-flow
situation, and at the same time, we have relatively high
concentrations of lead and the origins of the lead was
thought to be, for the most part, as a function of aerosol
dust hitting the surface of the ground, rainwater dissolving
it and moving it through the system and evaporating.
If this is the case, and we believe that it is,
since we see these low to moderate background values all
over the place and certainly at the surface sediments, one
can presume, I think very confidently, that down-flowing
fracture water, especially in fracture zones and fault
zones, contains a general background value of someplace --
of lead. I won't give you a concentration, because I don't
know.
But what I can say is if we had that water
dripping on a canister and that water was to go to
vaporation, the calcite, silicate, opaline product just
prior to or at solidification, crystallization, would
contain values very similar to the surface. That would be
somewhere between two and about 150 PPM, because it's
essentially the same waters that we see depositing these
deposits on the surface.
Other analysts, other papers in our references
have looked at, for example, trench-14 and here is that 150
PPM. So what we have done is we have not developed in this
analysis any unique or specific analytical numbers
ourselves. These are all out of the Department of Energy
literature existing today.
Again, lead PPM values are all over the place.
There's just a general background. I can answer the
question that's running through your mind of why are the
values so different. That's because essentially, when
you're precipitating stuff, it depends upon how much you get
in that particular -- how much water is going through that
system at that point or how active that area is.
We cannot get back to the water concentration
values using this analysis.
IF we ere to look at mercury values for veins,
pyretic and non-pyretic tufts, trench-14, we see that
there's a fairly distinctive variance, again. Veins seem to
be, of course, higher and these are probably associated, in
this particular case or in these cases, with some
hydrothermal activity, and that's why those numbers are
higher.
These are not necessarily the same as we just
looked at for lead.
I want to bring to your attention the basic
background numbers that we're getting for a regional vadose
water chemistry on lead as a product from that water
vaporation as a function of the USGS analyses and work.
We have a specific -- I have a little diagram
here, where -- once again, the surface waters are running
general meteoric and aerosol lead concentration, which is in
low PPM values, drips down a fracture zone and if that were
to contact the waste canister, the deposits formed that we
see in trench-14, for example, or, I'm sure, if we analyzed
some of the vein fillings at the Ghost Dance fault, we would
see the same kind of numbers.
We expect to see the same kinds of things
precipitate in the near field and a general feel for that is
anywhere around three to 150 PPM values.
I would like to turn this over to Don at this
point.
DR. HORNBERGER: If you had to put a pH value on
that cartoon --
MR. MORGENSTEIN: Eight.
DR. SHEWMON: You have a water level table in
here, wells, where, in those columns, would they be? Below
1,000 feet?
MR. MORGENSTEIN: Yes.
DR. WYMER: Before we go on, are there any other
questions on this presentation?
MR. MORGENSTEIN: Okay, this part of it, the first
half.
DR. WYMER: Any additional questions?
DR. GARRICK: You have given us some indication of
distributions and concentrations. What about time
dependencies, time information?
MR. MORGENSTEIN: Anywhere from the tertiary to
present day. I can tell you -- the only thing I can tell
you about time is if we go into the uranium deposits,
because we did run a uranium series run on the 3D uranium
deposits, and those were 180,000, 182,000, and they're, of
course, sitting in tertiary lava. So that's kind of cute
and it's of interest.
But my sense is that we're looking across the
board. I don't think it matters what time.
DR. GARRICK: I guess the question is what are the
dynamics over a three or 400,000 year timeframe of the
distribution and concentrations. What evidence do you have
that might suggest what the dynamics might be?
MR. MORGENSTEIN: Almost nothing. We have a
miniscule amount of data coming into us that we can find in
the literature. Remember, we're not out there analyzing
anything ourselves. We're in an oversight capacity.
DR. GARRICK: Right.
MR. MORGENSTEIN: So looking at the distribution
of these numbers through time, we don't see any patterns at
this point in time. But at the same time, there isn't
enough material data, authogenics data, at least well dated,
that we could feel confident in even reporting to you, if we
had some numbers.
Roger, did you have something to say?
MR. STAEHLE: Roger Staehle, I'm with the State of
Nevada. Just to possibly anticipate some of the questions
I've been hearing here, the amount of lead it actually takes
to crack this material, if you use the analogy of alloy-600,
which is the only really super-available analogy, it's only
about one to ten parts per million over the pH range from
about three to 13.
So we're not looking for a lot of lead here, just
to get that framework straight.
DR. STEINDLER: I guess I'm confused. We're
talking here about the lead content in solids. You've not
addressed, I believe, in any of these data, the lead content
in solution.
MR. STAEHLE: That is correct.
DR. STEINDLER: Thank you.
MR. MORGENSTEIN: The solids that we are talking
about in the case of trench-14 type solids were solids that
were deposited from vadose solutions as evaporates. So in
order to get where they are, they had to go through a
solution.
One of the unique problems at Yucca Mountain is
that if we go to, and I'm sort of stealing some of Don's
stuff here, but I'll let him get to it, if we go to looking
at water analysis, that is, saturated zone water, vadose
pore water and vadose fracture water for trace elements, we
are going to -- we have an extremely hard time in the
databank. There is hardly anything of value there. This is
a problem of characterization.
I'm going to go to Don and then if there are any
questions that pertain to the whole, we'll go back over
those. Don Shettel.
MR. SHETTEL: I will try and use this microphone,
although I think Maury just gave my talk. It will be rather
brief, which will become apparent.
Starting out with the USGS database, put out by
Perfect in 1995, this is a compilation up to 1994 of over
3,000 water analyses in the vicinity of Yucca Mountain,
three degrees of longitude by three degrees of latitude,
which is about 100 kilometers in north-south-east-west
direction, and this is a histogram of the data we get
ranging from almost down to one parts per billion up to over
a PPM, and these values actually are not necessarily
natural.
They're evaporative ponds sitting in buttes and
fall-out hills. So they've been evaporatively concentrated
and the range for natural lead in water is more in this
vicinity here.
DR. SHEWMON: That X axis is hard to see.
MR. SHETTEL: This axis is -- this is log --
DR. SHEWMON: Ten-to-the-minus-one?
MR. SHETTEL: This is log parts per billion. If
you look up here, I have it thousand parts per billion,
hundred, ten and one part per billion. This is log PPM lead
down here. Does that help?
DR. SHEWMON: Yes.
MR. SHETTEL: That's all the data that's available
to date, other than some more recent data, which I'm going
to show next. In the vicinity of Yucca Mountain, this is
most saturated zone water, spring deposits, and well water,
and, like I said, there's some artificial pond water here
that's been concentrated on the test site.
Now, if we move in closer to Yucca Mountain and
look at some individual data that we have, and most of this
is from the Nye County early warning drilling program that I
personally sampled. The only data we had from the USGS is
well J-13 and J-12 here. This is dissolved lead up to 16
parts per billion.
These wells are arranged from west to east. The
Bond gold mining well is on the western side of the Amargosa
Valley and the Funeral Mountain is on the boundary between
Amargosa Valley and Death Valley.
As we come across Amargosa Valley, to the first
western-most site of the early warning drilling program, 1D
site, we have this value. As we come down Highway 95 a
little more, we have the next well is 9SX. Then we have a
few values from here from Site 3. These are sampled at
different times and different depths during the drilling
process. There's at least two or three holes at this site.
2D is directly south of Yucca Mountain, along 95,
Highway 95, and then the wells on the test site, J-13 and
J-12, are in 40 Mile Wash, directly east of Yucca Mountain.
Finally, the well 5-S is southeast of Yucca Mountain, in
Oasis Valley, and this is all the data that's in the
immediate vicinity of Yucca Mountain.
Now, what you should note from this is there is
nothing vadose or these are all saturated zone samples.
There's nothing in the vadose zone or saturated zone in the
repository block.
DR. SHEWMON: Nothing, meaning no measurements,
not no lead.
MR. SHETTEL: No measurements of lead.
DR. HINZE: Let me understand. You're looking at
mercury and lead because of their potential corrosive
qualities and because you have some data. Is that correct?
MR. SHETTEL: I'm concentrating a lot in mercury
because that's what our consultants have done in the lab,
experimenting with the alloy.
DR. HINZE: Do you have information on any other
elements that are potentially corrosive or that might be --
MR. SHETTEL: I think there's -- the data that
I've shown is going to be typical of what's available for
anything else that you might want to consider, cadmium,
arsenic, antimony.
MR. MORGENSTEIN: And there are other values that
do exist for other things, and we're not presenting those
today.
MR. SHETTEL: But the lead is typical.
DR. HINZE: Is that because you haven't put them
together yet?
MR. MORGENSTEIN: We have not put them together
yet.
MR. SHETTEL: We're just concentrating on lead and
mercury today.
MR. MORGENSTEIN: As we maybe in the future
present findings of significance for other trace element
values in the laboratory, we will present their natural
background concentrations.
DR. HINZE: So what you're getting to, if I -- let
me make certain I understand -- is that there are a dearth
of measurements and that you would like to see additional
measurements.
MR. SHETTEL: Yes.
MR. MORGENSTEIN: Yes.
DR. HINZE: And can you tell us a little bit more
about what you think should be made available to properly
evaluate the corrosion properties of the vadose water, for
example?
MR. SHETTEL: Yes. I'll get into that.
DR. HINZE: Okay. Sorry.
MR. SHETTEL: Now, when we come to mercury,
there's even less data. We have one value from the
literature here, from Castor, which is half a part per
billion. Location unknown. It's from some EPA database
which we haven't traced down yet. It may be NURE data,
which would be the National Uranium Resource Evaluation
data, it might be from there, we're not sure yet.
In the Perfect database, which is the USGS
compilation, there's almost 100 values, but they're all
zero, which I don't know if that's analytical property or
what. But out of 3,500 analyses, less than 100 are listed
as not missing, but they're all zero. So you'd have to dig
back.
And then the one conclusion we can make from all
this is that the site characterization of Yucca Mountain, in
terms of trace elements in vadose and saturated zone water
within the repository block is incomplete and essentially
unfinished.
And this may be a shortsightedness or an oversight
on the part of DOE, not looking forward to what might come
up, such as what you're going to see later this morning, and
may be the result of their -- well, I don't know how to say
this, but bias or preconceived notions about what's going to
be important, the data that they need to collect during site
characterization.
DR. WYMER: Would you go as far as to say that
there's so little data available on dissolved mercury and
dissolved lead that you can't really draw any conclusions
about the corrosion that might take place in the repository?
MR. MORGENSTEIN: No.
MR. SHETTEL: Well, I think we have enough data in
the area to say that it is certainly present in the system
and if they had analyzed it in at least the saturated zone
water, they would have found it.
So I don't think there's any question that it's
there or not. They just haven't done the analyses for trace
elements in the waters.
DR. WYMER: So you don't really know.
MR. SHETTEL: We don't really know, but judging
from the data that's in the immediate vicinity of Yucca
Mountain, it's there, so I don't think there's any doubt
that they'll find it, if they analyze for it.
DR. WYMER: Okay.
MR. SHETTEL: I don't think that's a question at
all.
MR. MORGENSTEIN: Let me speak to that for a
second. What we don't have information on, from an aqueous
geochemical point of view, is any reasonable set of
analytical figures for Yucca Mountain and precisely Yucca
Mountain and precisely the individual types of water that
exist.
It's not sufficient to talk about the hydrogeology
of Yucca Mountain with respect to any of these trace
elements, unless we distinguish if they are coming from the
saturated zone, which is a really poor choice of target
water to look for.
DR. WYMER: That's right.
MR. MORGENSTEIN: But seems to be the choice --
MR. SHETTEL: I'll get into that here.
MR. MORGENSTEIN: -- at hand. We really are
interested in vadose water.
DR. WYMER: Sure.
MR. MORGENSTEIN: And we're interested in fracture
flow vadose water as opposed to just pore water, vadose pore
water. We need to know actually both.
Those numbers aren't there. We do have enough
information to know that lead and mercury exist in the
system in the aqueous phases and in the solid phases. We
don't have a way at this point in time to look at how much.
DR. WYMER: Okay. Thanks.
MR. SHETTEL: Oh, good, you just finished my talk
for me.
MR. LESLIE: Ray, this is Brent Leslie, from the
staff.
DR. WYMER: Yes.
MR. LESLIE: Can I ask a question?
DR. WYMER: Yes.
MR. LESLIE: Don, what is the minimum value of
water that you need to do these lead analysis, since you've
been doing them for the Nye County wells? This will help me
understand whether that volume of water is available, for
instance, in the thermal test.
MR. SHETTEL: Well, I use a leader, but that is --
we use that for lead analysis, as well as lead isotopes,
uranium isotopes and strontium isotopes, and those are all
done at MIT.
MR. LESLIE: Thank you.
DR. WYMER: Marty, did you have a question?
MR. STEINDLER: Yes. You indicated that, I guess,
most of your lead data in solution comes from USGS.
MR. SHETTEL: Well, in that 100 kilometer region
around Yucca Mountain, yes.
DR. STEINDLER: Right. Is there any information
on what else is in the water?
MR. SHETTEL: Yes. They have a whole series of
all the major analyses, cations and anions, as well as trace
elements. I've only shown you the lead and mercury.
DR. STEINDLER: So you know what the pH is. What
else?
MR. SHETTEL: If they've measured it, it should be
in the database, yes.
DR. STEINDLER: If they measured it. I guess I'm
asking is --
MR. SHETTEL: This is a compilation of literature
data that the USGS put together. Mostly, their data -- I
haven't gone over the whole database to show everything
that's in there. I just pulled out the lead values.
And, finally, a little digression on the use of
J-13. DOE has historically used it as reference water in
all experiments. However, as Maury pointed out, there
really is no vadose zone water sample from within the
repository block.
In other words, collecting a sample of dripping
water from a fracture. They have pore water that they
squeezed out of the rocks, again, the USGS has done this.
This is not necessarily an appropriate water to use to
represent water that's flowing in the fractures.
It may be more appropriate, as Brett mentioned,
from the thermal test, if it's determined that the canisters
are going to leak early on during a thermal pulse, then the
composition of the water that's been refluxed and circulated
above the drifts will certainly have a different and evolved
composition due to the refluxing and boiling and condensing.
And to further complicate problems, the
experiments that use -- they use synthetic J-13, they only
use major cations and anions in the water and they leave out
all the trace and minor elements, which you will see later
on this morning that these may be important for the
stability of the canisters.
So I have some conclusions here about -- mainly in
reference to water, vadose and saturated zone water within
the repository block, that the site characterization is
essentially incomplete, and that because of their
shortsightedness or however you want to put it, they may
have to go back and reanalyze samples or even re-collect
samples.
I pointed out above, experiments are missing
important components, major -- not major, but minor and
trace elements in the water, although they're starting to
add some of the elements that we're concerned about into
their alloy tests now, I believe.
But the bottom line is they're not using a
realistic aqueous environment in any of their experiments,
especially as it refers to canister materials.
DR. WYMER: By environment, you're talking about
concentrations of --
MR. SHETTEL: Talking about the -- yes, the --
DR. WYMER: Not temperature, pressure, anything
like that, because you haven't discussed that yet.
MR. SHETTEL: No, I'm not going to discuss
temperature. I'm really just concerned about the
concentrations of elements in the aqueous solutions.
DR. SHEWMON: It bothers me some --
DR. GARRICK: Paul, can you move your mic closer?
Thank you.
DR. SHEWMON: To rephrase that last statement, I
would prefer to say that it's unrealistic to talk about an
aqueous environment for these casks, but then that's --
MR. SHETTEL: Why is that?
DR. SHEWMON: Because there's no -- you said the
water level was down a thousand feet or more. They aren't
submerged in water, are they?
MR. SHETTEL: No, but there's water that flows
through the fractures and can drip onto the canisters. The
unsaturated zone is almost 80 percent saturated by water.
DR. SHEWMON: That's not an aqueous environment.
It's sort of running through in --
MR. SHETTEL: Once you heat up the rock and drive
the water out of the rock, you could have water, more water
dripping into the drifts.
DR. SHEWMON: It's dripping on. It's not an
aqueous environment. Well, you can call an aqueous
environment parts per million --
MR. SHETTEL: Well, it's certainly a human
environment and with the water dripping -- no, you're right,
it's not going to be necessarily submerged in water, but
they can have water dripping on there, the water can
evaporate and build --
DR. SHEWMON: If that's what you mean by an
aqueous environment, that's fine.
MR. SHETTEL: Well, but in the lab, they do their
tests in an aqueous environment.
DR. SHEWMON: I know. I think that --
MR. SHETTEL: They submerge the sample.
DR. SHEWMON: -- makes them largely irrelevant,
but it's the only place, the only light we can look under.
MR. SHETTEL: No, I don't think that I'd say that
it's irrelevant.
MR. GORMAN: Can I make a comment, please? Jeff
Gorman, Dominion Engineering, with the State of Nevada team.
You should remember that the most aggressive corrosion for
carbon steel piping in PWRs occurs when you have dripping
borated water dripping onto the carbon steel and staying a
little bit wet, but being concentrated to a high
concentration.
You can chew through the carbon steel at an inch a year and
that's widespread occurrences and we have to watch for that
in plants, because of this dripping concentrating to near
draw-out, but not drawing out, is a very aggressive
condition and that seems like a possibility with these
canisters.
DR. WYMER: Is that equally aggressive -- let me
ask you a follow-on question. Is it equally aggressive in a
totally emerged environment of the same material?
MR. GORMAN: No. If you're totally emerged --
well, boric acid solutions are aggressive if it's also
oxygenated. And so if it's -- the boric acid inside the
PWR, that solution is not aggressive against carbon steel
because it's fully de-aerated with a hydrogen over-pressure.
Many cases, when it leaks onto really hot pipe and
it dries quickly and stays dry, you don't get corrosion.
You get the worst case when you have enough dripping to keep
it at about 200 to 250 Fahrenheit and moist and then you get
very aggressive -- truly you chew big holes in pump flanges
and in vessel walls and the like.
DR. WYMER: This line of reasoning suggests that
tests in total immersed solutions are not necessarily
appropriate.
MR. GORMAN: That's correct. We'll be discussing
that. We'll talk about that, some improved ways of testing.
DR. WYMER: Okay.
MR. AHN: Ray, we have -- there are a couple of
questions here.
MR. CRAGNOLINO: This is Gustauvo Cragnolino. I
only want to provide two pieces of information. One is in
response to the question of Dr. Steindler regarding the pH.
Typically, the pH for the solution that he described within
dissolved lead concentration going from one PPB to one PPM
is ranging from 7.5 to, at the most, 8.5. This is the range
of pH for the solution that he was describing.
The second one refers to the speciation of lead when you
have borated water. We tried to do some very simplistic and
preliminary analysis by running the GWB code using, as a
baseline, the concentration of anionic and cationic species
that you have in J-13 water.
But doping the water with the maximum value, both
the lead concentration that he has in solution, is about 3.1
milligram per kilogram of water, three PPM.
When you remove the water by this process of
evaporation in the code, you come out with the conclusion
that mostly lead is either precipitated, a cerrusite, that
is lead carbonate, and the remaining solution is the
dissolved form of lead carbonate, with a concentration on
the order of 1.2-ten-to-the-minus-three molar.
There is an ion pair association between lead plus
two and carbonate in the aqueous phase to this
concentration, while free lead, two plus is the order of
ten-to-the-minus-14 -- minus-12, I'm sorry.
DR. WYMER: Pretty insoluble.
MR. CRAGNOLINO: The concentration on the other
side reaches the range of the order of 1.4 molar. Then we
are getting close to saturation to the concentration
solution.
But this is only to give you a framework. It
doesn't mean that these are experimental data, by any means.
It's a simplistic calculation with a code in order to seek
out the operation process to lead to the concentration of
lead in the water.
MR. AHN: One more question here. Tae Ahn, of NRC
Headquarters. Have you considered the current design of the
EBS system including a drip shield, that blocks the water
drip during the thermal pulse period?
MR. MORGENSTEIN: Have we considered that? We
will be talking about that later, and, yes, it's been
considered.
DR. WYMER: And along these lines of this general
conversation, have you considered the effect of sulfide on
reducing the --
MR. MORGENSTEIN: Yes.
DR. WYMER: -- free ion -- I mean, that really
knocks it down.
MR. MORGENSTEIN: Yes.
DR. WYMER: We'll hear about that?
MR. SHETTEL: Yes. You'll hear about possible
effects of sulfate.
DR. WYMER: Sulfate.
MR. SHETTEL: Being reduced on the canister
surfaces.
DR. WYMER: Then being sulfide and then
precipitating into the lead and the mercury.
MR. SHETTEL: Well, it has other effects, I
believe, other than that. Roger Staehle will talk about
that.
DR. WYMER: Of course, effectively removing the
lead and the mercury is another whole area of consideration.
You're going to get into that.
DR. STEINDLER: Can I prolong this discussion just
a little?
DR. WYMER: That's what we're here for, Marty.
DR. STEINDLER: The conclusion I guess I come to
is that in solution, which is what you were talking about,
the variability of the lead content of the various samples
that you get are what you call all over the map.
MR. SHETTEL: In a sense, yes, but they are within
a fairly restricted range. I mean, they fall within the
part per billion range, yes.
DR. STEINDLER: In the aqueous phase.
MR. SHETTEL: In the aqueous phase, yes.
DR. STEINDLER: There seems to be no systematics
which would allow you to predict where you would find high
or low concentrations, even in that part per billion range
that you're talking about.
MR. MORGENSTEIN: That is correct. What we can
tell you is probably what the range is. So we have bounding
ranges.
MR. SHETTEL: You have bounding ranges.
MR. MORGENSTEIN: That could be used at this
point. But as you could tell, we're not feeling very
comfortable. We would like to have a lot more information.
MR. SHETTEL: You can also use a geochemical
modeling program, such as EQ36, to evaluate the chemistries
of the solutions, if things are in equilibrium or not. I
mean, we haven't gone that far yet. That certainly could be
done.
DR. STEINDLER: The level of uncertainties at
those concentrations strikes me as being excessive in terms
of being able to predict your concentrations, particularly
the --
MR. MORGENSTEIN: We have no argument with you.
We totally concur.
MR. SHETTEL: Yes. You have to know something
about the geology, as well.
DR. STEINDLER: The other point then is in the
case of mercury, you're totally without information. Is
that right?
MR. MORGENSTEIN: From an aqueous phase, that's
totally correct.
DR. STEINDLER: Don't have a clue.
MR. MORGENSTEIN: Don't have a clue.
MR. SHETTEL: We know it has to be fairly low and
probably lower than lead.
DR. STEINDLER: Yes. We know it's there.
MR. MORGENSTEIN: I think you now it's there.
MR. SHETTEL: You know it's there as a solid
phase.
DR. STEINDLER: I'm talking about solution.
MR. MORGENSTEIN: In the solution, we have not a
clue.
MR. SHETTEL: That's right. But if you're going
to heat up the repository and reflux water in there, the
increasing temperature is probably going to increase the
lead concentration in the water.
DR. STEINDLER: I'm sorry. I moved to mercury.
MR. SHETTEL: I mean mercury, yes. We're still
talking about the same thing.
DR. STEINDLER: But since you don't know whether
there is any mercury in the solution, you can't --
MR. SHETTEL: We don't believe that that's
important whether or not it's actually in the solution right
now.
DR. STEINDLER: How would it get to the --
MR. SHETTEL: The important point is that --
DR. STEINDLER: -- if it isn't in solution?
MR. SHETTEL: If you heat up the repository and
start circulating hot thermal water in there, you could be
drawing the mercury out of the rock.
DR. STEINDLER: Do you have any evidence to
substantiate that?
MR. SHETTEL: The hydrothermal deposits are
mercury. It happens in nature.
DR. STEINDLER: I'm talking about evidence that
relates to Yucca Mountain.
MR. SHETTEL: I'm going to be measuring mercury in
water. Next week I'm going to be sampling. So we will try
to get some mercury data in water. Not within a repository
block, but along Highway 95, where the Nye County early
warning drilling program is sampling next week.
DR. STEINDLER: What's your limit of detection in
the case of mercury?
MR. SHETTEL: I think it's below a part per
billion.
DR. STEINDLER: Below the part per billion.
MR. SHETTEL: Yes.
DR. STEINDLER: Do you have any idea how far below
the part per billion?
MR. SHETTEL: Not at the moment, no.
DR. WYMER: I don't want you to answer this
question now, but to alert you to the question so you can
talk about it later.
Do you have any idea, with respect to the
characterization that you're going to need, you need a lot
more data from the mountain, so that you really can pin some
of these things down. You need more characterization
information.
MR. MORGENSTEIN: We would not even consider that
characterization has taken place yet.
DR. WYMER: That's what I was going to ask you
later on and maybe you people can't answer the question,
maybe DOE has to answer it.
MR. SHETTEL: Yes. We think DOE needs to
characterize the mountain in a more thorough fashion.
DR. WYMER: What I was concerned about out was the
time in which this characterization can take place and then
when the characterization results will come out with respect
to the licensing process.
MR. SHETTEL: That's a question for DOE.
DR. WYMER: That's a question for DOE, I realize
that, but I thought you might want to kick it around a
little bit later on.
MR. MORGENSTEIN: We obviously have the similar
concern.
DR. WYMER: Okay.
MR. MORGENSTEIN: Unless there are further
questions --
DR. WYMER: We've got one.
DR. HORNBERGER: Don, I can infer from your last
slide the criticism that no dripping fractures have been
sampled in the ASF and that that's part of the
characterization that you're talking about.
MR. SHETTEL: Yes.
DR. HORNBERGER: Would you suggest that what has
to be sampled is water from the seepage tests in the cross
drift or water from the thermal test that's in progress?
MR. SHETTEL: I believe the thermal test does have
some water analyses and I just got a copy of one of their
reports.
DR. HORNBERGER: But my point is that you --
MR. SHETTEL: The seepage tests in the drifts --
DR. HORNBERGER: -- want to collect water from the
fractures.
MR. SHETTEL: Yes. That would be one -- we feel
that that's one part of the characterization of the mountain
that should have been performed.
DR. HORNBERGER: Right. But I guess I would
probably argue that you are going to -- if you sit out there
and wait for a naturally dripping fracture to give you a
liter of water, you might be characterizing for a very long
time. That is, you don't see water dripping from those
fractures. It's not like the Stripa Mine and --
MR. SHETTEL: Not in the ventilated parts of the
repository, you don't. You'd have to sit in a part that's
closed off to ventilation, yes.
DR. HORNBERGER: So, again, you're saying that
what should be sampled is if they do get water, and that's
not clear yet, in the sealed-off drift, number one; number
two, in the thermal test, which is --
MR. SHETTEL: I believe the thermal tests have
been sampled, yes.
DR. HORNBERGER: Okay. And then would you
consider data from leaching from a seepage test useable?
MR. MORGENSTEIN: Let me speak to that. We're
sitting with hardly anything now.
DR. HORNBERGER: Yes, I know.
MR. MORGENSTEIN: Everything at this point in time
is useable.
DR. HORNBERGER: Okay.
MR. MORGENSTEIN: A window of information is
better than a closed door.
DR. HORNBERGER: I'm just trying to put the
criticism that we don't have vadose zone water dripping from
fractures to characterize in perspective.
MR. SHETTEL: They do have UZ14, which is the
perched water, which they sample.
DR. HORNBERGER: Sure.
MR. SHETTEL: Although that's --
DR. HORNBERGER: So you would consider perched
water to be --
MR. SHETTEL: -- not necessarily exactly the same
as the fracture water.
MR. MORGENSTEIN: Certainly.
MR. SHETTEL: But on a seepage test, you mean with
artificial recharge? Well, that's data. It's not
necessarily the natural system, but it is data.
MR. MORGENSTEIN: It would be better than what we
have.
MR. SHETTEL: Better than nothing.
DR. WYMER: Better than nothing, yes.
DR. HORNBERGER: Again, Brett asked you how much
you wanted and you wanted a liter of water per sample.
MR. SHETTEL: Well, that's just what I collect,
but that sample involves a lot of other things, as well.
It's not the minimum amount necessarily.
MR. LESLIE: Brett Leslie, from the NRC staff. I
mean, one of the places where potentially DOE has 35,000
liters of water is alcove-1, where they've forced
infiltration and have collected that water, and I guess the
question I would kind of toss back to you is the transit
time is a couple days to a couple weeks, is that useful
information. That's water that's flowing down fractures and
dripping and --
MR. SHETTEL: Did they use J-13 water for that,
Brett?
MR. LESLIE: Yes, they did.
MR. MORGENSTEIN: One of the things that you have
to recall is that the lead signal, the background lead
signal is a surface expression and so that if you take J-13
and inject it into the system, you may not be dealing with
reality.
But at the same time, you may be. We'd have to
keep that an open issue. But, yet, any activity that would
produce any numbers at this point in time would be welcome
and the more, the better.
MR. LESLIE: Are you saying that bad data is
better than no data?
MR. MORGENSTEIN: I wouldn't call it bad data.
MR. LESLIE: But that's in essence what you've
said. You said any data.
MR. MORGENSTEIN: Well, any reasonable decent
data.
DR. WYMER: These are literalists.
MR. MORGENSTEIN: I apologize. If there are no
further questions, we'd like to go to our next presentation
from Jeff Gorman and Ronnie Barkatt.
DR. STEINDLER: Ray, are we going to get copies of
the viewgraphs?
DR. WYMER: Yes.
DR. STEINDLER: It would be useful.
DR. SHEWMON: We have them, I think. Some of us
do.
DR. GARRICK: Well, our designated Federal
official got to supply it.
DR. WYMER: Would you introduce yourself, again,
please?
MR. BARKATT: Dr. Morgenstein already introduced
the team in general. The consulting group that we are
involved with consists of personnel from Catholic University
here in Washington, D.C. and Dominion Engineering of McLean,
Virginia.
My name is Aaron Barkatt and we have several other
members of the team, Dr. Pulvirenti is here in the audience,
Dr. Chuck Marks from Dominion Engineering works with Dr.
Geoffrey Gorman, and Dr. Geoffrey Gorman will give the other
half of the presentation, and, again, there are several
other people at Dominion working within this group.
Catholic University has been working for several
years with Dr. Morgenstein for the State of Nevada, mostly
on glass issues, and the project that we started here on
C-22 is evaluation to development, this whole effort only
started in the spring, several months ago, and the results
that we have got are necessarily just preliminary in nature.
We should also reemphasize that we have -- we are
making no effort here to compete with or to overlap the DOE
efforts. Our mission, as we see it, is to supply the State
of Nevada with information as to whether, in our opinion,
the DOE program adequately addresses all the significant
issues related to the waste package alloys and,
specifically, the C-22, or whether the other aspects, in our
opinion, that we think ought to be considered further.
In that context, the aspect that we started
addressing at the beginning of the program was the effects
of minor species and trace species which may have a
significant effect on corrosion.
This concern is the result of Dominion
Engineering's experience, as well as own experience in the
nuclear industry, but as Dr. Staehle will detail in his
talk, this is not by far the only issue and may not even be
the most important issue to address with respect to the
C-22, where we think that further consideration, further
study may be merited.
Many others, the nature of the heated concentrated
surface that we are dealing with, and he will speak to that
point. But I would think that one reason why we started
with aggressive species is it's easy to do preliminary
experiments and, of course, our purpose is to go into more
systematic studies that allow us to judge better the
relevance of our results to the expected repository
conditions.
So what we are doing here is exploring acid and
caustic environments with and without, so far, lead and
mercury. We've just scratched the surface with respect to
arsenic and sulfides.
Most of the tests were done with U-bends mostly at
the temperature of 250 degrees Centigrade, as well as disks,
unstressed disks at 160 degrees Centigrade, but, of course,
a much milder condition.
The base medium which we were looking at is J-13,
and, again, you heard at length the concerns about the fact
that J-13 may be not the most appropriate water for testing
relevant to repository conditions, and I think that's an
understatement.
This water is concentrated by a factor of a
thousand and that, again, is a an arbitrary number. We use
it because for DOE or Lawsonberg and coworkers analyzed the
one thousand concentration factor extensively. That's not
the maximum concentration that may occur.
Again, we are planning to use geochemical codes and if I may
add, in digression to an issue which was brought up in
response to the previous presentation, things can really get
complex -- excuse the bad pun -- with regard to lead
solubility, because, for instance, we know that there are
carbonates, we know the limitations on solubility in
carbonate systems, but there, again, it has been published
that in systems exposed to radiation, formation of organic
acids, formic acid, acetic acid and so on is observed, so
that situation may be very complex.
So what we tried to do here essentially is to take
a first cut at looking at wherever potentially aggressive
species, such as lead and mercury, may have significant
effects on C-22 corrosion.
MR. GORMAN: I'm Jeff Gorman, of Dominion
Engineering. We started the -- did this series of tests
with U-bends, which we'll show a picture of in just a
minute, and so you can see the size and shape. This is of a
flat sheet of C-22 and then was stressed with a nut-and-bolt
kind of thing, squeezing it.
We chuck the strain that we estimated was about 25
percent on the OD surface. So highly, highly stressed
U-bend samples and put in static autoclaves and in a variety
of environments.
Let's see. I think that I should use this. Here
is essentially all of the tests at 250, except one at room
temperature, and with rather a range of pH, some very acidic
at room temperature, not quite so acidic up at as calculated
pH at the 250 C, and some of the samples had wells in them
and some did not, and some we added samples of tuft material
in them and those are marked "yes." And then the
accelerants is with sulfuric acid. One test had applied
potential of 200 millivolts and these were short duration
tests, generally in the neighborhood of a month.
And in some of these environments, we saw no
results, nothing either visual or in terms of cracking or
pitting and the like, no -- while others, we saw definite
signs of chemical attack, ranging from tarnishing to slight
pitting, to very severe pitting, and then one specimen, this
one here, specimen number 12, cracks through wall.
We'll show a picture and we can pass the pieces
around. In quite a short time. We saw the crack in the
first inspection after one week, and fully fell apart after
two weeks. So then this is at an elevated temperature, 250,
but it's a very short time, and the question is, as you
reduce temperature towards more realistic, how long does
that time become.
DR. STEINDLER: Were these solutions de-aerated
before you used them?
MR. GORMAN: Chuck, no, they were not.
DR. STEINDLER: Do you have any idea of what the
oxygen content was?
MR. GORMAN: Well, it's starting in seven PPM
range, but the acidic ones probably the oxygen was consumed
very quickly, I would assume.
DR. STEINDLER: What was your free board volume on
your autoclave?
MR. GORMAN: Chuck, what's the volume in the
autoclave? It's, I think, listed.
MR. MARKS: Chuck Marks, also at Dominion
Engineering. The liquid volume in the autoclave was about
150 mils and the head space above that, which was air, was
about 100 mils.
DR. STEINDLER: So it's about one-to-one.
MR. MARKS: Just about, yes.
DR. SHEWMON: One other question. At 250 C in
that, the pressure is 1,000 PSI?
MR. GORMAN: No. Let's see. A thousand PSI is
288 C, so my guess is something in the 600 PSI, something
like that. There's further results are shown here and the
main -- the main point on this -- these are the same test
samples. The main new information or the concentrations of
the elements showing that a fair amount of dissolution of
some of the elements took place in these environments,
showing some chemical activity going on.
Again, in the same ones, the same general ranking,
with this number 12 being the most severe and then the very
severe pitting one being the next most severe, one with lead
and the other was mercury.
DR. WYMER: Why did you go to such high acidities?
That seems very unrealistic.
MR. GORMAN: The reason was is we only had a very
short time to do some tests and --
DR. WYMER: You wanted to see something.
MR. GORMAN: We wanted to see something and we
realize that these are rather -- these are aggressive
environments and the intent is then to, first, find out
where things happen and then start working in a systematic
way towards service conditions, allowing us to extrapolate
to longer and longer times.
Let's see. I think this is the time to the now
fractured pieces around. I'm going to pass it in the
envelope, so you can take it out and look at it. These are
this sample here. We'd like these -- oh, if anybody wants
to see a U-bend, we can pass that around, but it's not very
exciting.
DR. WYMER: Do you think that the stress that you
got there is anywhere close to what would be present in a
container?
MR. STAEHLE: Yes.
MR. GORMAN: Roger will discuss that. This was at
a -- we didn't quantify the stress. It would be up over the
yield stress, whatever level cold work would occur getting
to 25 percent strain.
So it would be at a high stress, but you could get
to such surface stresses at a damaged area on the surface of
a canister, for example.
More pictures of cracks, which I guess are not
terribly --
DR. GARRICK: You're going to have to install the
microphone on your --
DR. STEINDLER: While you're doing that, let me
ask a question here. You mentioned the pH at room
temperature. In some cases, you're up at 250. Do you have
any clue as to what your pH is at 250, especially in the
acidic solution?
MR. GORMAN: We show the calculated pH there, if
you look at the table, the next column over. It's
calculated room temperature -- I mean, calculated at
temperature pH.
DR. STEINDLER: And that took into account that
you've got an air over-pressure.
MR. GORMAN: No, I don't think it did.
DR. STEINDLER: I'm trying to figure out what that
means.
MR. GORMAN: I don't think we -- we did not take
into account the -- any effect of air.
DR. STEINDLER: Okay.
MR. GORMAN: I guess I'm going to flip through a
lot of cracks. You can see it, it's in the handouts.
Now, we also see a fair amount of evidence of
under the washer, which was isolating the nut-and-bolt from
the U-bend. We also see a fair amount of sort of crevice
attack, pitting kind of crevice attack.
DR. WYMER: What was the washer made out of, same
stuff?
MR. GORMAN: It was Teflon. Oh, no, excuse me.
Chuck will come up and --
MR. MARKS: The bolting mechanism was a similar
alloy to C-22, but there were Teflon liners in between the
bolts and the washers and the sample itself.
So there was no metallic contact with the bolting
mechanism.
DR. WYMER: What was the ionic strength of these
solutions, roughly, do you have a feel for that?
MR. GORMAN: Chuck, the ionic strengths? It's
listed, I think, on the --
MR. MARKS: We have a listing of the specific ion
parts per million. We don't have a molarity or anything
like that concentration. The autoclaves were also
Teflon-lined. So there was -- so the samples were isolated
completely, except for the solution contact.
MR. GORMAN: Just to show some more details of the
cracking. You can see sort of general pattern of
intergranular attack occurring. The sample -- the crack
growth direction is in this direction. This is the OD
surface. This is the ID, transgranular to about sort of
approximate midpoint, and then intergranular thereafter.
So transgranular in the higher stressed area, then
the final propagation at lower stress in the intergranular
mode, with lots of little intergranular starts along the
surface at other locations.
So the lead environment, the acidic lead
environments are quite aggressive against this material.
DR. WYMER: Were there some cracks before you ever
put it in the autoclave?
MR. GORMAN: Not as could be seen under visual
examination. We didn't do metallography beforehand.
DR. WYMER: Under the same condition that you saw
those cracks, you did not see cracks before.
MR. LEVENSON: They didn't do that.
MR. GORMAN: Let's see. In visual examinations
like this and some visual examinations under a
stereomicroscope, we don't see any cracks in the surfaces of
any of the samples, except for this one after test.
DR. WYMER: Okay.
MR. GORMAN: The only cracks that we have seen.
DR. STEINDLER: Excuse me. I'm slowly catching up
to you. Your sample 12, which was -- you don't need to go
to it, but which was the lead --
MR. GORMAN: That was the lead acid.
DR. STEINDLER: The lead acid, had a significant
amount of what looks like either deposits or whatever around
where that Teflon --
MR. GORMAN: Washer was.
DR. STEINDLER: -- washer must have been. Did you
look at that to see why that was there and whether it
indicated the thing that I think Ray was driving at, whether
you had electrolytic reaction?
MR. GORMAN: I'm not sure. I don't think I
understand your question, but, Chuck, let's get up to the
microphone? Because he's the one who actually looked at
these in greatest detail as he took them out. So repeat
your question again.
DR. STEINDLER: In that sample, in the lead acid
sample, it looks like there's a fairly non-uniform reaction
layer which surrounds what apparently was the location of
your Teflon.
MR. MARKS: Yes. Why don't you put up the slide
of sample 12, showing the --
MR. GORMAN: Yes, just a second.
MR. MARKS: -- bolting location?
MR. GORMAN: Right. Just a second.
DR. STEINDLER: Sorry about that.
MR. GORMAN: That's fine. I don't think these are
deposits. I think that's pitting, isn't it?
MR. MARKS: Yes. Basically, what you see is there
is a smooth circular region around the hole where the bolt
went through and then just beyond that, there is some severe
pitting in the location that was essentially a crevice
formed by the Teflon liner and the U-bend sample.
So we're looking at some accelerated corrosion
there in a crevice type region. In this particular picture,
you don't see any deposits. They've been washed off. There
was, because the J-13 water concentrated by 1,00 times did
have some precipitates in it, there were salts located on
the sample immediately after the test, but in this
particular picture, they have been washed off and what you
see there is pitting.
DR. STEINDLER: I guess all I want to do is draw
attention to the fact that there seems to be something going
on in the area of that magic nut and bolt.
MR. GORMAN: We were attributing it to crevice
effects, but I couldn't swear that it isn't due to something
from the Teflon.
MR. MARKS: Most likely it's a crevice effect.
The Teflon is supposed to be non-reactive in these
conditions and the bolt was an alloy C-276, which is
actually very similar to the C-22 and we would not expect
any kind of chemical reaction to be accelerated to this
extent by the differences between those.
DR. STEINDLER: Those of us that have had to do
MCC-1 tests will tell you that Teflon is not inert and you
can get a significant amount of fluoride out of it,
especially at the temperatures and conditions that you were
using.
MR. MARKS: Our conclusions about this particular
sample and the pitting that you see there are also based on
the fact that the same bolting assembly was tested in other
environments and, specifically, the lead acid is associated
with this phenomenon, as well as the mercury samples.
DR. SHEWMON: Did you do any of these experiments
at pH .5 without the lead?
MR. GORMAN: Yes.
DR. SHEWMON: I don't see any in the tables.
MR. GORMAN: The other ones, like this one here.
DR. SHEWMON: That's got sulfur.
MR. GORMAN: It's got sulfur in it, but the -- go
ahead, Chuck.
MR. MARKS: But at that pH, most of the sulfur
that was originally put into the solution is volatilized
during the pH adjustment. So the amount of sulfur there is
--
DR. SHEWMON: This is a closed autoclave, isn't
it?
MR. MARKS: Yes, but the pH adjustments are made
before the autoclave is closed and before the sample is
added. So there are certain adjustments made to what we
call the 1,000 X J-13 order.
MR. GORMAN: The answer is we didn't do any tests
without any additives and only the acidic, which would be
interesting to do. We haven't done that, but our thought is
that this one is pretty close to that condition.
DR. SHEWMON: We aren't sure whether it's the lead
or the conditions yet.
MR. GORMAN: But we're pretty confident that it's
the lead.
MR. CRAGNOLINO: This is Gustauvo Cragnolino, from
the Center for Nuclear Waste Regulatory Analysis. I was
precisely going to ask the question that Dr. Shewmon asked,
because I think that it is very important to have a blank
test under the same conditions with the absence of lead.
When we reviewed the literature on these subjects
several years ago in handbook on the stress corrosion
cracking, we found out data precisely produced at that time
by Haynes and Judy Kolls, showing that the alloy-22 is
susceptible to stress corrosion cracking, one weight percent
hydrochloride, hydrochloric acid, the pH is about .5 at room
temperature, when you test this at 232, using a U-bend
sample without lead.
I don't deny that it could be an important
accelerated effect of lead, but it has to be clearly
demonstrated here and I think that the way to sort out this
situation will be to have a blank test in which you are
completely sure that you don't have lead.
MR. GORMAN: And in the test program, we would
expect to do so. So this is suggestive, but not conclusive,
is our position at this stage.
If you go to that last sample we were just looking
at, which did not -- let's see. Had I -- let's see. I
wanted to -- I think I may have passed over that in response
to a question. This was the mercury acid, where no cracking
occurred, but we still saw some pretty severe pitting and
crevice kind of attack.
Then the one with the sulfur, where we think most
of the sulfur was removed, also saw some crevice attack.
DR. WYMER: What is chemically, sulfur acid, what
does that mean?
MR. GORMAN: It's on the -- earlier in the table,
it gives the environment. Chuck, do you want to answer that
in more detail?
MR. MARKS: Yes. Specifically, what we did was to
the 1,000 X J-13 water, we added sodium sulfide, NA2S, at
3,200 PPM sulfur. But upon acidification, there was a high
degree of volatilization of the sulfur, even through the
hood.
So the speculation is that sulfur levels in that
particular sample were not necessarily higher than any
others.
MR. GORMAN: This, we are now to disk tests.
Ronnie, if you're going to stand up, you're going to want
this on.
DR. SHEWMON: Will you have on your slide
something, what the concentration is in C-22 before the
test? I don't carry that around with me somehow.
MR. BARKATT: The C-22 composition --
MR. STAEHLE: The average compositions are nickel
56.5, chromium 21, this is all weight percent, molybdenum
13.5, tungsten 3, iron 4, and cobalt 2.
DR. SHEWMON: Thank you.
MR. BARKATT: The tests that you heard described
before were done, as you heard, under fairly severe
conditions, because we wanted to start under accelerated
test conditions and then start working backwards towards
milder conditions.
And the second series of tests which was done, it
had significant distinction from the first one. First,
instead of using stressed U-bends, these tests were done
with unstressed static disks of alloy C-22.
Secondly, the temperature, instead of being 250
degrees Centigrade, was about 160 degrees Centigrade. And
thirdly, when you look at environment, we used the J-13
water concentrated by a factor of 1,000, without attempting
to acidify it in the first eight rows of the table, and then
we also did acidified tests, but we acidified only to pH .5,
not all the way to .5.
I should also note, in passing, that in these
tests, we used the Teflon vessels, where very, very aged,
had been used at elevated temperatures in water for a long,
long time, and I would expect that based on previous
experience, by that time, the fluoride extraction from the
Teflon was not a significant factor.
Anyhow, we'd like to take a look at the chemical
analysis of the solutions after contact with the C-22 and at
least at the high pH region, we have a case where we had no
additives, so that can serve as a baseline, and this was
really a preliminary scoping test and please remember that
we are talking here about very preliminary work.
So we threw in everything that we could think of,
a lot of it, additives that have been suggested, as a result
of the DOE program. And I would like to direct your
attention particularly to two lines, one of them is the
lead, where we added, admittedly, a high concentration of
lead, but you can see here that with respect to chromium and
molybdenum, at the high pH, you have an enhancement by a
factor of about -- oh, I'm standing right in front of the --
DR. SHEWMON: You said high pH and pointed at 2.5?
MR. BARKATT: No, no, no. I was pointing to these
top nine lines, the pH at room temperature is about 13 all
the way down to here.
DR. SHEWMON: You said you singled out two of
them.
MR. BARKATT: I singled out -- let me single out
three. No, which is a mark to one, no additives, which
serves as our baseline. The row marked lead, introduced as
lead acetate, the second row, and you can see here an
enhancement in the concentrations of chromium and
molybdenum, which may or may not be significant.
At this stage of the program, it's premature to
ask about uncertainties and standard deviations and so on,
but there may be some enhancement here by about a factor of
two.
But when you go to the ninth line, the last line
of the pH results, with mercury, you have enhancement in the
concentration of these two dissolved elements, the chromium
and molybdenum, by about a factor of 30 and that is even
more likely to be significant.
With regard to the pH 2.5 experiments, here, of
course, you see larger amounts of the solution, higher pH,
you will notice, for instance, within the case of mercury,
you have what appears to be a significant enhancement of the
dissolution of molybdenum.
Now, again, admittedly, we don't have a line here
which says none, but we did do the test with no additives
and, again, because of the preliminary nature of the test,
we did not, in that case, analyze the concentrations, but we
had the samples and we could examine them.
DR. STEINDLER: I'm sorry. I don't think I've got the
picture yet. This is the concentration in the residual
solution.
MR. BARKATT: This is the concentration in the
residual solution.
DR. STEINDLER: So these are comparable because
the sample size surface area and the volume of the liquid
were the same --
MR. BARKATT: Were the same in all cases. Let me
start by discussing --
DR. STEINDLER: I'm just trying to make sure that
what I'm comparing is apples and apples.
MR. BARKATT: Apples and apples. All these disks
came from the same lot. I may have misunderstood the
question. Jeff, would you mind passing these along? One
comes from the blank test, the other comes from the
lead-containing test. And the pictures that we have here are
even worse than the ones -- the ones which you saw before
were really good. These ones were done, again, pretty
hastily and with less than optimum equipment.
But the one thing that we saw in the
lead-containing sample was an obvious evidence, clear
evidence of pitting, plus we saw a lot of the position of
corrosion products.
The case of mercury is peculiar. The case of
mercury, we have one sample that I think we didn't
characterize too much, because the filter won't let us get
it out, it's too much, with a reasonably deep pit, which
shows layers of chromium oxide and what may be molybdenum,
but this is -- these tests, again, need to be reproduced,
continued and the conditions need to be specified to the
extent that we can clearly distinguish why, in one case, we
did get a deep pit in the presence of mercury and in other
cases we got a multiplicity of shallow pits instead.
So we are not -- we cannot talk about the mercury
effects conclusively at this stage.
When we look at the main findings --
MR. GORMAN: You might as well go ahead. Why
don't you go ahead on this one, Ronnie.
MR. BARKATT: When we look at the main findings on
the U-bend tests that you saw before, what you can see here
is that in an acidified solution without additives, and so
to resolve the current contradiction, when you introduce
sodium sulfide into a solution at room temperature that
contains acid at the pH .5, practically all the sulfur is
driven out as hydrogen sulfide, and that's why we can talk
about that.
Without additives, the corrosion is mild and
involves shallow general corrosion and pitting, possibly
with some deposition, and, specifically, in the stressed
region along the apex of the U-bend, we see very, very
little alteration. I should say we don't see significant
alteration of the sample at all.
In the presence of mercury, we see general
corrosion, pitting, and deposition of corrosion products.
All these modes.
Now, there is something peculiar about the
mercury, which may have to do with our analytical
techniques. We tried to use EDX on these samples. Again,
that was preliminary, with obsolete equipment, and we have
not observed mercury accumulating on the corroded surface.
DR. WYMER: Why did you go to 1,000 full
concentration instead of, say, 100 or 10,000?
MR. BARKATT: Again, there is a recent paper by
Lawsonberg, I think at Lawrence Livermore, which
characterized at great length the 1,000 concentration factor
and related it to EQ, for EQ6 modeling results and there is
where we felt comfortable that we had a solution which is
pretty well characterized.
But, again, in all reality, there is no reason
that the concentration would stop at the factor of 1,000.
DR. WYMER: Yes, that was my point.
MR. BARKATT: And we'll try to do something about
that, which we'll talk about in a moment.
Okay. With acidified solution in the presence of
lead, we see the cracking occurs at first in the
transgranular mode. It may even start as pitting, going
transgranular, and then follows and intergranular mode as
the stress is relieved as a result of the cracking.
We see numerous secondary cracks, mostly
intergranular. The corrosion part of deposition is
observed. Pitting may proceed with transgranular cracking
and a large amount of lead concentrates at the crack
surface.
EDX results show between six and 11 percent
concentration of lead on the surface of the C-22.
DR. WYMER: Would you repeat that? I'm sorry.
MR. BARKATT: The EDX measurements show that
between six and 11 percent lead on the surface of the C-22
after it's been removed and washed.
DR. WYMER: Percent with respect to?
MR. BARKATT: In EDX, you get the top few microns
of the sample.
DR. WYMER: So it's that percent with respect to
the alloy.
MR. BARKATT: With respect to the composition of
the surface, that's the composition of the surface.
MR. GORMAN: It would be with respect to sort of
the average penetration depth of the --
MR. BARKATT: Of the EDX, which is a few microns,
five microns. The top five microns of the surface, and
somebody may want to correct me, to two microns.
DR. WYMER: Okay.
DR. STEINDLER: But it's uniform across that
surface.
MR. BARKATT: Again, it's not uniform. It varies
between five or six percent and 11-12 percent, but it's high
in all cases because we measured in a few spots, yes. I
think we had three or four independent measurements.
DR. STEINDLER: These samples were used as cut.
MR. BARKATT: These samples were used as cut,
after washing, yes. They were removed, thoroughly washed,
and then cut. Yes.
DR. STEINDLER: And the cutting was done with a
cutting fluid?
MR. BARKATT: The cutting -- no, no, no, no, no.
That was the experiment -- I'm trying to recall. I think --
DR. SHEWMON: If you look at the back of the
sample, it looked like a hacksaw. I mean, the fracture
surface wasn't damaged, but it was made small enough to put
in these EDX machines, with a saw.
MR. GORMAN: I seem to recall she talked about
dry-cutting. I don't know.
DR. SHEWMON: Keep going.
MR. BARKATT: Do you remember if she used cutting
fluid or not?
MS. PULVIRENTI: April Pulvirenti, Catholic
University. Even if she used a hacksaw, she wouldn't be
cutting on the surface that was cracked. The cracked part
was already open. She wouldn't have cut that, and I thought
the SEMs were on the crack surface, the inner surface of
that.
MR. GORMAN: Yes, they were on the crack surface.
MR. BARKATT: Okay. The disks. In the case of
these disks, what we saw in the case of the disks was strong
pitting on the surface of the specimens that were exposed to
lead. We saw extensive deposition of corrosion products.
A very large amount of lead concentrated on the
pitted surface. And now I think that I caught myself with a
major boo-boo. The 11 to 12 percent we observed on -- no.
Okay. Take it back, and I'm sorry about this.
On the crack surfaces of the U-bends, what we saw
was five to six percent of lead accumulation. On the disks
which were exposed at 160 degrees, we observed up to 11 or
12 percent of lead, again, in the top few microns of the
disk. Again, in this case, no cutting at all was done, just
washed them and we did run the analysis.
And ongoing tests indicate that in the case of
these disks, to mercury pitting, and, again, I would like to
emphasize that in the case of these unstressed disks, we did
run blanks. The blanks did not show any evidence of
corrosion at all under microscopic examination.
DR. WYMER: What was the lead chemical species on
the surface?
MR. BARKATT: Acetate. Yes, we introduced it as
acetate.
DR. SHEWMON: When you do your EDX analysis,
you're washing, as you phrase it, and it takes off the salts
and what you're analyzing is lead deposited on the fracture
surface.
MR. BARKATT: Yes. All in the case of the disks,
the surface of the disk.
DR. STEINDLER: How do you know it was acetate?
MR. BARKATT: What we added was acetate. That's
how we put it in.
DR. WYMER: That's what I was after.
MR. BARKATT: What was it after? We don't know.
DR. SHEWMON: But on the surface, there was
metallic lead.
MR. GORMAN: You get a lead signal from the EDX,
but you don't know --
MR. BARKATT: The EDX cannot tell you which
species it is.
DR. WYMER: That was my question.
MR. BARKATT: So the main findings on the
unstressed disks, the acid pH, pH room temperature of 2.5,
both lead and mercury caused extensive dissolution of the
C-22 ingredients.
In the pH 13 samples without acidification,
mercury, and here I would have to modify, I shouldn't say
but not lead, but I should say much more than lead, because
lead, again, may have a moderate enhancement of corrosion,
caused a moderately significant dissolution of chromium and
molybdenum.
IN general, the surface characterization and wet
analysis both agreed with respect to specifically lead
concentrating on the surface of the exposed surfaces.
Now, we tried to follow up --
DR. WYMER: If lead was on there as lead acetate,
it's hard to think of a mechanism that would cause
preferential precipitation on the surface, which gets back
to the significance of what actually was the lead species on
the surface.
It seems to me that's fairly important.
MR. BARKATT: Let me try to address it in the
following --
DR. WYMER: Okay. Please.
MR. BARKATT: So the question is really whether,
if lead and mercury are present in the repository water,
they could have, in fact, and all we are saying at this
point is that that possibility needs to be explored. But
coming back to the specific question of what happens to the
lead when C-22 is present, we are concerned that just
looking at concentrations by themselves may not be
sufficient, because if there is lead in solids surrounding
the C-22 containers and water gets into the system, the
concentration in this water may be very, very low, maybe
very, very low, but this water still can communicate with
other solids in the repository environment.
In that case, our concern is whether it's only the
concentration which is important or the total quantity of
lead that is available, that is around, and may end up in
full migration with the water acting as an intermediary,
interacting with the C-22 surface.
The question is whether C-22 actually absorbs,
reactors, we are not sure of all of the mechanisms at this
point of time, with lead and other aggressive species.
Of course, we have indications, as you heard in
the previous talk with Dr. Morgenstein, that lead is present
in solids, in natural solids in the repository environment,
and even more lead may be introduced as a result of human
operations, construction and operation of the repository, as
components of various metals that would be present during
these operations.
Now, if we are dealing with water that contains
lead and the only important effect is concentration, it
means that only the lead present very close to the surface
will interact with the C-22 and the rest will remain in the
solution and eventually find its way out without ever
interacting with the C-22 surface.
If, in the other hand, we have a mechanism that
provides for adsorption or chemical reaction between that
lead in the water and the C-22, causing the lead to be
scavenged by the C-22, then we may need to consider a much
broader availability of lead because as lead concentrated on
the C-22 surface, it may be replenished from other available
solid sources in the environment.
And so what we tried to do in these experiments
going on right now, these are experiments in progress,
again, we are using those disks, again, the J-13 water at
temperature of 160 degrees, we are looking at a variety of
pH. Again, we are limited -- our experiments so far have
been limited to ten to 14 days.
We are looking at various levels of lead
introduced into the system and we are measuring the lead in
the original solution and in the solution after contact with
the C-22, to verify the fate of the lead.
We are also starting to do acid etching on the
C-22 surface of the disks after they have been removed from
the solution and in one case, we have what looks like an
initial rough materials balance with respect to the lead.
Again, these results are very, very, very recent.
DR. WYMER: What acid?
MR. BARKATT: Dr. Pulvirenti?
MS. PULVIRENTI: This is April. These were nitric
acid.
DR. WYMER: Thank you.
MS. PULVIRENTI: At pH of 2.5.
MR. BARKATT: So we have a table here, we have one
more data point which hasn't even found its way into the
table yet, but I will give it to you orally.
What you see here is that we start with lead
concentrations ranging between 35 to 125 to 275 PPM before
contact with the C-22, and after contact with the C-22, we
end up with five or one or 14. In other words, we have
somewhere between about 87 and 95 percent removal of the
lead from the solution onto these C-22 disks.
Now, the extra data point, because lead
concentrations may be very low, is at one and a half PPM, I
think, to be exact, 1.4 PPM, initial lead, we ended up with
0.03 PPM of lead in the solution after removal, so that's,
again, about 98 percent removal.
And in this case, we had an acid etch and the acid
etch did account -- again, we had a rough materials balance,
but it did look as if the lead coming off the surface of the
C-22 in the acid etch accounted for most of the difference
between the initial solution and the final solution.
DR. WYMER: Did you analyze the solution for any
of the constituents of the alloy?
MR. BARKATT: The solution has been analyzed for
constituents of the alloy, as well.
DR. WYMER: Did you look for a relationship
between the amount of lead deposited and the amount of alloy
dissolved?
MR. BARKATT: These are ongoing experiments.
MS. PULVIRENTI: Do you mean the initial and final
of chromium and molybdenum? We have that. As yet, we don't
have a materials balance. We have numbers, but I don't
believe that they're accurate, because in addition to these
results, we also see some chromium oxide type deposits.
So the numbers would be less than what we would
expect if any of those alloys originally dissolved from the
disk would be trapped within those deposits.
DR. WYMER: I was looking for sort of a stochimetric
equivalence between the amount of lead deposited and the
amount of alloy dissolved.
MS. PULVIRENTI: We didn't see it. Now, we saw --
in all cases, we did see quite a high -- yes, I would say
quite a high concentration in inventory of dissolution of
chromium, molybdenum and nickel, but we didn't quite see --
we didn't see a nice linear increase as a function of
initial lead concentration.
DR. SHEWMON: This was done at room temperature?
MR. BARKATT: No.
MS. PULVIRENTI: This was done at 160 degrees
Celsius.
MR. BARKATT: All these experiments are at 160
degrees. Again, in response to a comment that was made
earlier, we are not looking only at aqueous environments.
We have an ongoing experiment with wet pate, as well, where
we went to the concentration limit.
MS. PULVIRENTI: We have that. Do you want to see
it? No. Okay.
MR. BARKATT: Do you want to talk about that? I
mean, it's really preliminary. These are experiments which
have come out in the last two or three days and we really
need more time.
This is about time for a break. So I think we'll
go, while this is still fresh on our minds, I'll ask for
questions, additional questions from anybody.
MR. AHN: Tae Ahn of NRC Staff. In actual
scenario analysis, they considered drinking water rather
than static water. That's my question, have you considered
adsorption under the dripping water conditions? That's one
question.
The second one, again, DOE, in the EDX design,
included drip shield that preclude dripping water. Can you
comment on that?
MR. BARKATT: Again, we apologize for the
preliminary nature of the experiments at this point. These
experiments under dynamic conditions are certainly being
planned and Dr. Staehle may address that.
But at the present time, again, we tried to answer
a question more qualitatively.
MR. CRAGNOLINO: I have a general question. My
name is Gustauvo Cragnolino, Center for Nuclear Waste
Regulatory Analysis.
I notice that most of the tests tend to be done at
low pH or at high pH. Do you plan to do sensing in the pH
in which, for instance, species like carbonate, many people
agree completely with what was said before, that J-13 cannot
be, by any means, representative of the water that comes
into contact with the waste package.
However, the main anions are there. If you go
very acidic pH, you're removing the C02 from the system.
That means that you don't have this species that is very
important in controlling the precipitating process. And if
you go to alkaline, you end up with species like this.
I think my question is, do you have plans to do
the study of these type of impurities in the intermediate pH
range?
MR. BARKATT: Experiments in the intermediate pH
range are going on right now, in progress, and we plan to do
many more.
MR. STAEHLE: Gustauvo, the data for alloy-600,
just as a possible paradigm here, shows that cracking occurs
readily at about a PPM to ten in neutral solutions, just
absolutely pure water, with lead oxide. So the pH is a
non-issue here, the first approximation.
DR. HORNBERGER: Does that include carbonate
species?
MR. STAEHLE: No. This is just pure water with
lead oxide.
DR. SHEWMON: As you know, the stress corrosion
cracking of these nickel-based alloys has been aggravated by
the chloride, and it just dawned on me, the only one of your
tests that has a very high chloride concentration is the one
where you found stress corrosion cracking, is that right?
You added HCL to this stuff to get the pH down to
.5.
MR. GORMAN: But there were a couple other tests
with the same HCL, but other additives where we didn't get
cracking.
DR. SHEWMON: But they weren't at .5?
MR. GORMAN: Yes, they were at .5. I think there
were three different tests at -- two tests at .5 and one --
I guess it was the W15 did not crack, while 15 did crack.
DR. SHEWMON: Fine. Thank you.
DR. STEINDLER: Just a comment. If your lead
absorption proposal holds water, then you should be able to
soak up essentially all the lead in the solution if you dip
some lead into it. Does that make sense?
MR. BARKATT: What we know, and I think Dr. Gorman
might be able to comment on this much better than I do, but
if we take a look at industry experience, then concentration
of lead on crack surfaces is a well known phenomenon. It
eventually should be able to remove all lead from the water
phase.
MR. GORMAN: Just to cite an example, which I
happen to have been working on recently for once-through
steam generators. The lead in the feedwater, it's very
difficult to measure at low levels, but it's estimated with
reasonable reliability at being ten PPT in the feedwater
coming into the bottom of the steam generator.
Up in the upper part of the steam generator, where
it's boiled dry and the super-heated region, recent tests
with sensitive XPS methods and with ATM methods have shown
that lead in the percent levels of three, four, five percent
is detected under the oxide layer on the tube surfaces and
in crack faces.
So this coming in at ten PPT, it's the Inconel-600
in this case, is able to absorb and concentrate lead on
surfaces and it appears to be having -- it's thought to have
an effect on the cracking that's being experienced in this
upper bundle region of these generators.
So that's -- and fairly often, in other steam
generators, recirculating steam generators, we find lead on
crack surfaces, even though the lead in the feedwater is
typically -- and in the blow-down water is thought to be in
the ten to 30 PPT range.
You find it in the percent range on fracture
surfaces.
DR. WYMER: We do have one ACNW -- oh, I'm sorry.
MR. MORGENSTEIN: I just wanted to reiterate the
fact that we believe that there is a general lead
concentration in the vadose water coming from the
dissolution of surface aerosol material and although we
could not, at this point in time, give you what the
concentrations are, we believe that you could get as much as
between three and five PPM solid product from waters in the
vadose.
And if that is a general background number out
there of some, say, one PPB or .1 PPB, and we do have a
surface sorption characteristic for C-22, this is a fairly
serious situation.
DR. WYMER: Well, we do have perhaps one ACNW
staff member on the telephone. He's home ailing with a
strained back. Andy, are you there? Andy's laying down.
MR. CAMPBELL: Can you hear me?
DR. WYMER: Yes, we can hear you. Do you have any
questions, Andy, or anything you want to add?
MR. CAMPBELL: I guess that the real issue, in my
mind, is I'd be surprised if any natural water or even
static water of any sort did not have lead in it at some
level. What that level is, as was pointed out, an open
question for things like the vadose zone water, and in the
experiments that DOE and other people have done, it hasn't
been measured, but there may be lead concentrations in those
waters of some unknown amount and whether or not they're
relevant, without those measurements, it's hard to say.
But the other issue, in my mind, is the speciation
of the lead under the various conditions and what is the
important lead species that, if there is a relationship to
this stress corrosion cracking, what is it.
And then if you know what that speciation of lead
is in the water, you do you get this cracking, then are you
going to get some sort of intersection of conditions you
might expect in the Yucca Mountain repository environment
with the kinds of experiments done in systems where this has
occurred, and anybody can answer that, if they want.
DR. WYMER: Or address it.
MR. GORMAN: Can I make one comment on it? With
regard to autoclave testing of lead and its effect on
alloy-600, tests have been done with lead metal, lead
sulfide, lead chloride and lead oxide, and all have been
approximately as aggressive.
It hasn't been -- the additive species to the
autoclave has not had any significant effect on the results.
So there's no particular speciation as far as for
600 mil annealed. Related to that, in pure ACD -- that's
all volatile treatment water, which would -- at temperature,
would be essentially near neutral, at 320 Centigrade, 4,000
hour C-rings at 25 percent of stress, low stress, .1 PPM of
lead can cause cracking of 600 mil anneal and one PPM, quite
clearly, but down to about a tenth of the PPM in just pure
water won't crack it.
MR. CAMPBELL: And, again, the question at had is
depend -- I mean, you can add all kinds of different sources
of lead, but the question is what is its speciation once
it's come to some sort of equilibrium in the water where you
are seeing the cracking, and then are you going to see that
kind of speciation under various repository types of
conditions.
MR. STAEHLE: One possible answer to that, if
you're looking, as Jeff pointed out, that whether it's lead
or PVS or PVO, when those dissolve in water, you end up with
PV-double-plus. So essentially, from a speciation point of
view, you're looking at lead-double-plus and also in that
range of oxidizing potentials, that's always possible.
So the options you have is either lead metal, the lead metal
to lead oxide equilibrium is about the same place as the
standard hydrogen equilibrium.
So there is actually some mechanistic question
about whether you've got lead metal or lead plus two, and
that's a mechanistic issue that has yet to be resolved.
So, anyway, I think that maybe partially answers
the question.
DR. WYMER: I think it's a very important
question.
DR. STEINDLER: But I think the chances of you
ending up with lead-double-plus in the solution that's got a
tenth of a percent chloride in it is very small. This 1,000
X J-13, in a sense, screws up the standard chemistry.
MR. STAEHLE: Sure. But let's start with
something simple. This experiment is just one set of
experiments and if you look at the broad set of data that
are available for alloy-600, exposed to lead, and start with
something simple, like PVO, forget the chloride, just PVO
and water, that's a place to start and that is quite
sufficient to produce all the cracking you would see here.
So then if you then expand that -- one of the -- I think the
implication of the question that you just asked, and I'm
sorry, I forgot your name, but the implication of the point
is that, in fact, in operating steam generators, you
sometimes see a lot of lead in deposits and you don't see
any cracking.
Wait a minute. Why is that? Well, probably
what's happening is, in fact, the lead is reacting to form
some -- more in soluble compound. You just lower the
activity of the lead.
So there is an issue here about equilibrium with
other lead activity affecting systems, and I think that's
certainly relevant to the point you made.
MR. CAMPBELL: That is basically the point I'm
making, is that until you get a handle on the speciation,
and I will say, at 320 degrees C, under some equilibrium
vapor pressure, you may very well have -- in fact, you
almost certainly have different speciation than you would at
25 or 30 C under atmospheric pressure.
And you'll get pressure/temperature changes with
speciation. So that seems to me to be the key here to
getting the handle on this, is how is the lead speciation
changing under these various conditions in terms of
relevancy to corrosion, stress corrosion cracking in steam
generators versus conditions in Yucca Mountain.
Anyhow, yes, that is the point.
MR. BARKATT: If I may add one comment. With
regard to lead, again, at the present time, we don't have a
handle on the speciation. With regard to mercury, recent
observations showed information of mercury metal, metallic
mercury, in contact with the C-22 under these conditions.
DR. WYMER: I think we probably need to declare a
break. The break was scheduled for 15 minutes. Let's get
back no later than ten minutes till 11:00, if you will.
[Recess.]
DR. WYMER: It's ten of 11:00. Let's go ahead and
get started. We do have a cutoff time of noon. So we're
going to have to move along.
Let's go ahead and get started, whoever is next
here.
MR. GORMAN: I think I am. The purpose of this
next section was we were asked by the State of Nevada just
to review the history of material selection and material
problems in nuclear power plants to get some ideas as to
what sort of problems we ought to stay alert to when looking
at the engineered barrier system.
And so I've not tried to be exhaustive. I've
picked some of the ones that are most significant to the
industry and ones which I happen to have worked on, so knew
the situation pretty thoroughly, without a great deal of
work.
And what they show is that despite good intentions
having been involved in the selection of the materials,
there have been lots of problems, which has made a nice
living for me for 40 years, but nevertheless.
DR. WYMER: Not 40 certainly.
MR. GORMAN: Well, since '59. So 41.
DR. WYMER: You're aging well.
MR. GORMAN: No. Okay. First example is BWR
stainless steel cracking, with the -- in piping and
internals. Piping was the original one. Currently, the
main problem is with the internals, where the stresses are
lower and the cracking growth rates are lower.
But people are wrestling with it. And the main
causes -- the material was selected because of its good
general corrosion resistance.
What seems to have been ignored or not enough attention paid
to was the effect of sensitization at wells, the effects of
the oxidizing potentials caused by radialytically produced
oxidants, and effect of residual stresses and cold work due
to grinding on accelerating crack initiation.
By the way, Roger is going to be talking about
many of these subjects in some more depth in a little bit,
and so I am going to whip through this so as to not steal
his time, because we're getting limited on time.
Inconel-600 or alloy-600 used for steam generator
tubes has experienced very widespread cracking. Many of the
steam generators made with the 600 mil annealed material
have had to be released, and lots of money and lots of plant
downtime.
The reason Inconel was selected was primarily
because of its good general corrosion resistance and
resistance to chlorides, because if you remember, back in
the '50s, there were cases of cracking of the stainless
steel tubes due to the chlorides and testing showed that the
higher nickel alloys were resistant to that kind of chloride
induced stress corrosion cracking.
What that selection seems to have failed to
consider was a very large range in susceptibility as a
function of the processing history and minor compositional
varies, at least a thousand times in some tests in pure
water, in primary water environments.
So very large range in susceptibility as a
function of rather minor changes, seemingly minor changes in
how the material was made and its composition differences,
like trace levels of boron, for example, have a big effect
on the resistance to caustics.
The effects of low potentials, cold work and
residual stresses on primary water stress corrosion
cracking, on the other hand, the effects of oxidizing
potentials and the concentration of impurities under boiling
conditions, which can lead to high or low pH and to
aggressive -- high conductivity solutions and can
concentrate aggressive species, such as lead, to
intergranular attack and secondary and stress corrosion
cracking from the secondary side, which is the current main
biggest problem in the still operating steam generators,
with 600 mill anneal.
And as I already mentioned, the effect of minor
elements in the metal, particularly boron, its resistance to
stress corrosion.
Most of these high strength materials or at least
some of the high strength materials, I think X750 and A286,
both precipitation hardening austenitic alloys, this one
being nickel-based, this one being steel -- iron-based, were
selected primarily for their high strength and were from
aerospace applications.
There have been a lot of failures of those two
and, also, 17-4 pH and martensitic stainless steels, with
lots of bolting having been replaced, expensive repairs in
reactor internals and the like.
They were selected based on their general good --
their good corrosion resistance in terms of general
corrosion resistance, but sufficient attention wasn't paid
to the possibility of stress corrosion cracking in long-term
exposure in reactor environments for material that was
actually in the actual heat-treated condition.
Again, effects of local residual stresses in cold
work were commonly not given enough attention and in the
case of particularly 17-4, the effects of time at
temperature on its embrittlement and susceptibility to SEC
wasn't taken into account.
It's now pretty well shown that at over 500 F, the
17-4 in a long period of time, after several years, will
start to degrade, and that wasn't recognized back in the
early days.
And then a big point on particularly the 17-4 and
the martensitic stainless steels, you can meet specified
mechanical properties, the kind of things you see on your
mill cert, but have very poor stress corrosion cracking
resistance as a result of thermal mechanical heat
treatments, not following the prescribed sequence.
So there was the need for much tighter quality
control in the fabrication to make sure that the materials
actually saw the times and temperatures specified.
DR. SHEWMON: Before you change that, was most of
this in PWRs with the hydrogen over-pressure or was it also
in BWRs?
MR. GORMAN: On the X750, it's more a -- well,
it's both BWR and PWR. Both, both. I mean, like the BWR
jet pump beams and in the core bolting at shoes, for
example, of the PWR, so it's both. The A286 is all PWR.
The 17-4 pH is a mix of both and martensitic is a mix of
both. A286 was early identified as being a problem with the
oxidizing environment in BWRs and wasn't much used.
Ziracalloy cladding, chosen for its good corrosion
resistance and its low neutron cross-section. The main
thing that wasn't identified was its susceptibility to
stress corrosion due to fission products such as iodine and
cesium and when stressed, after the clad creeps down and
then you get pellet-clad interaction, leading to the stress
corrosion. So that's been a big problem over the last 20
years or so with zircalloy clad fuel.
Sort of trying to summarize, what lessons should
we learn with regard to thinking about choice of alloys for
difficult applications. You got to have a full range of
realistic crevice environments and with all of the
parameters, the potential, the pH, and aggressive species.
You have to have the full range of realistic
material conditions and compositions, including things like
welding and stress relief operations and local surface
damage is often a big effect.
So realistic range of total stresses, especially
including residual stresses and from things like surface
damage or from fabrication operations.
You've got to test for long times in realistic
environments, with accelerated methods, and then work
towards ever more realistic, but longer term tests to try
and predict to the total service conditions that you're
trying to protect against, the long times at lower, less
aggressive conditions.
I had mentioned this, the aggravating effects of
the fabrication details and surface damage, and I guess you
can't over-emphasize that, because lots and lots of cracks.
On steam generator tubes, for example, many times, the
cracks are at surface scratches made during tube insertion.
And long-term material aging has to be considered,
because material properties can change with time.
DR. STEINDLER: Would you agree that the results
that we've heard so far do not include attention to some of
these parameters that you were talking about here?
MR. GORMAN: Yes. That's the next slide.
DR. STEINDLER: Oh, sorry. The main lesson is
you've got to consider all of those factors. You can't
afford to neglect any of them, and some of them may not have
been -- we're being very cautious. I'd say clearly have not
been, but for written things, we'll say may not have been
suitably addressed.
DR. SHEWMON: Could you tell us where the C-22
alloy has been tested out, where it was developed for what
kind of service?
MR. GORMAN: I'll let Roger address that. Roger,
development of C-22, what kind of service? I think it was
for acid chemical service, primarily. But I haven't studied
that in great depth. Go ahead.
MR. MARKS: Basically, when you look at the alloy
chemistry, with the molybdenum and tungsten and chromium,
it's basically an acid service alloy and it's basically not
developed for neutral or alkaline environments.
I'm going to talk about that in some detail in a
minute.
DR. SHEWMON: Fine.
DR. HINZE: When you talk about long-term tests,
give me an idea of what you're talking about.
MR. GORMAN: I think we can start getting a feel
for it in tests within about two years. But I think for a
10,000 year application, getting to tests that can last five
or ten years is not unreasonable to try and --
fundamentally, what you do, let's take just temperature as
the aggravating factor.
Probably, you'd also use stress, too, but you do
tests, first, up at a high temperature where you see some
effect, and then you reduce the temperature, say, by 50
degrees C and then see how long it takes, and then you go
another step temperature lower and you then start getting
results that you can extrapolate on a log-log plot,
basically, developing an arrhenious activation energy.
But since we haven't done the tests at the lower
temperature, we're not sure how long we're going to have to
go for any given temperature.
DR. SHEWMON: And you also have to bet that the
mechanism doesn't change fundamentally when you change
temperature, which this test won't show you.
MR. GORMAN: Right, you have to take an estimate
on that.
DR. HINZE: Is there experience with C-22 in terms
of these long-term tests?
MR. GORMAN: Not that I know of. Talking about
the status of testing of C-22, we've been through the
literature to some extent and not as thoroughly as we intend
to in the next few months, and it looks like they haven't
addressed trace aggressive impurities, such as the lead
arsenic, mercury and sulfides on SEC and other modes of
corrosion, such as the crevice corrosion and pitting.
They don't seem to have addressed the range of
water chemistries and concentrations that occur,
particularly under heated crevices and deposits. You sort
of envision -- you have this canister that's going to be at
pretty high temperature, initially, I think, as high as 200
C, but up over 120 C, at least, for significant periods of
time.
You have some deposit, either rust or tuft or some
kind of material on it. You have a drip on it that
concentrates. It can go -- it's like a steam generator
crevice. It can go from pH of two to pH of 12, depending on
the mix of species. So those kinds of conditions haven't
been tested.
I think they've started looking at some material
composition variations, but I haven't seen any systematic
work on trace deleterious species, such as boron and carbon
and this sort of thing, and the various conditions that
might occur as a result of the fabrication route that they
use.
So we are intending to start a more extensive and
systematic test program. We're going to try and identify
the mechanisms that we got to pay attention to, pitting,
crevice corrosion, intergranular attack and stress
corrosion, and then determine the effect of crevices and
deposits, the pH, aggressive species concentrations and
potentials, and the resultant effect of these chemistry
changes on the corrosion phenomena; in other words, a
systematic set of tests.
DR. WYMER: Let me ask you. Presumably, in order
to get at this alloy C-22, you've got to go through the
titanium drip shield. Is there any reason to believe that
you ought to be looking at either of the states of titanium
on any of these tests?
MR. GORMAN: I haven't considered that at this
stage. I think Roger has got the task of trying to consider
the overall thing, so I'll leave it to him to address when
he gives his talk in just a minute here.
Let's see. My last slide is -- so our objective
is to develop a scientifically based way to predict the
long-term performance of C-22 using accelerated experiments
with -- as time goes on -- progressively less accelerated
conditions and looking at the ability of the C-22 to
scavenge and concentrate aggressive species, such as the
lead, as we were talking about, the mercury and others, and
determine how do you determine -- how do you assess what
level of aggressive species, is it the total quantity in the
inventory in the world around the container or is it the
concentration in the water, what is the important parameter.
We really don't know the answer to that yet.
So I know turn it over to Roger, unless there are
questions for me. No questions.
DR. WYMER: Well, now, let's not be too fast here.
MR. GORMAN: Roger, are you going to be standing?
Then you will want this.
DR. WYMER: An awful lot of questions got shoved
down to your end of the table, Roger. We're going to see
here.
MR. MARKS: You know what they say about what
rolls downhill. Some years ago, I think in 1992, I was on
the same program with a friend of mine, Bob Way, who some of
you know, at Lehigh, a very fine guy, and he at -- we were
at the point where we were talking about predicting things
and he was saying, well, you just absolutely can't make a
prediction until you understand absolutely the atomistics of
the problem.
And later, after his talk, I said, Bob, not in
your lifetime or your children's lifetime or their lifetime
will you know the atomistics of the problem, and so you have
to deal with kind of what's in front of you in the best you
can do doing intelligent experiments.
And we're kind of in that framework, where there's
a lot of things we'd like to know, but maybe we have to use
a lot of judgment here and a lot of analogies.
Now, just to point out where we're all at here,
this is not -- this is out of the DOE report, we're
basically talking about this container wall here and the
C-22 is on the outside surface, fuel is on the inside
surface, the titanium drip shield is on the outside.
So for those of you who need some refresher,
that's essentially the framework that this discussion is in.
Now, I have some number of slides and they're all
in my pass-out and I'm not going to talk about all of them,
because I know that, first of all, you all read very well
and some of these things don't need to be said particularly,
and I'm going to start with this idea about maybe we could
learn something from history.
For those of you who are unfamiliar with this
technology, this is a steam generator in a pressurized water
reactor. The hot water comes in the bottom, in the bottom
plenum, goes through a tube, exits through and goes back to
the reactor to be heated. The inlet temperature is around
320 to 330 Centigrade, the outlet temperature is around 395
or so.
Steam exits here around 290 Centigrade. Now, the
reason this is a useful set of ideas for discussion is that
we're going to be interested particularly in the crevices
between this Inconel or alloy-600 tube and these tube
supports.
And we're a little bit more interested in this
joint here, because the -- it's an analogy for concentrating
surfaces. It's also an analogy for a surface which is not
otherwise stressed, except for fabricating stresses. And
there is an issue here about -- the question was raised,
well, what's the stress and what's the relevance of a
U-bend.
What I want to point out is that the as-fabricated
tubes, as I will show you shortly, cracked just fine as
fabricated, as mill annealed. So we don't really need to
have an enormous set of stresses to make cracking occur.
So this particular joint is relevant for two reasons. One
is the concentration that occurs under heat transfer
conditions and the second is the fact that the tube is not
seriously stressed, except for an internal pressure, which
is about net 1,000 PSI, and there's a little bit of thermal
stress, there's a drop of about ten degrees Centigrade
across the wall.
That's not as much as the drop across the waste
package container, but anyway, so it's not a bad analogy and
so we can learn something from this and I would like to lean
a little bit on that as a basis for my discussion.
Now, in the beginning, I mean, in the beginning
was different times for all of us. My beginning was about
1957, when I first joined the Naval Nuclear Program and I
have been thinking about reactors ever since.
Let me compare something. I'm going to compare
the steam generator with the waste package and, for example,
there are four areas where there are interesting
comparisons.
One is the appearance of an adequate test
environment. In the early days of the steam generators, it
was thought that a fossil water chemistry of in excess of
100 parts per million was an okay water chemistry. Today,
just for sake of comparison, the EPRI standard is around ten
parts per billion.
It was thought that the alloy-600 was an immune
alloy and for those of us who worked for Rickover many years
ago, it was said that actually God himself created this
alloy and God himself was, of course, Rickover.
If you don't believe that, you should have worked
for him. Anyway, and here we have C-22, which is, again, to
quote DOE, is a corrosion-resistant alloy. And the third
area of comparison is the heat through crevices,
concentrating impurities, as I mentioned, and here is the
heat through the surface, this surface also capable of
concentrating impurities.
In this case, the early design objective was a
40-year life based on fatigue. Here, it's a 10,000 year
life based on what I'll tell you later is basically a BWR
stress corrosion model.
So that's a little bit of analogy about the reason
there is a reasonable comparison here from which we can draw
some understandings.
Now, just to make the point here, this happens to
be capacity loss in BWRs, capacity loss in PWRs, and the
point is virtually all this capacity loss was due to
corrosion.
So despite the fact that there's some wonderful
engineers working on this, the fact is that we still had
lots of problems.
Now, in terms of the idea, essentially the analogy
for prediction, again, in the DOE prediction discussions,
they're talking what essentially is about a predictive model
that comes out of the BWR technology, where we're talking
about oxygenated water exposed to weld, whereas in the PWR
analogy, we're looking at the condition where we concentrate
impurities and I have the residual stresses on this side,
which is, I believe, are much more analogous and useful idea
than the BWR example.
Now, I'm going to use a framework for my
discussion which I call the corrosion-based design approach.
It's a general way of approaching a design problem from a
corrosion point of view.
I'm not going to belabor it, just except to say
that I'm going to emphasize the discussion on environmental
definition, material definition, mode definition,
super-position. I won't talk about the failure definition
or statistical framework and a little bit about prediction.
Now, when we think about designing environments
that are relevant, the environment that's relevant here is
the environment on the surface of the metal. It's not the
environment out someplace. It's what actually ends up on
the surface of the metal.
So that's where our focus has to be. The next
point in defining environment is the heated surface produces
a totally different environment than an isothermal surface.
And the third point I want to make is -- this is
for those of you who are geologically inclined -- it may be
an overstatement, but the entire -- from the point of view
of thinking about chemistry on surfaces, you've got to start
with the bounding condition that the entire surface and the
mountain is relevant to the heated surface.
I realize that sounds like a stretch, but you have
only to look at what I'm going to show you in a minute about
what ends up in the crevices of steam generators.
You think, well, this is really pure water. I
will show you in a minute what ends up in these crevices.
It's like the thiosulfate in TMI-3. How could
this thiosulfate ever get into the steam generator and
produce all those cracks? Well, it did and it wasn't
supposed to. It's like the sea water leakage at Millstone.
It wasn't supposed to get in, but it did. It's like the
sodium that cracked some of the LFBMR technology. It was
supposed not to get outside, but it did.
So while this is clearly a hand-waving argument, I think we
have to be sensitive to the idea that when something is an
environment of some impurities, things do have a way of
getting there somehow. And so while it's logically a little
bit hard to argue with, it is nonetheless something you've
got to start with.
Now, the other problem we have, of course, is no
feedback control here on environmental contamination.
There's no conductivity meters, there's no local chemical
analysis. So we have a problem that we don't have in other
technologies.
Then, of course, the thermal gradients in the
Yucca Mountain site produce flows we hadn't expected and
another aspect of the environment is that the highest
concentrations, like chloride, which is the dominating idea
in the DOE work, are not always the most aggressive
conditions.
I mean, it would seem like chloride is always the
most aggressive thing. Wrong. Chloride is not always the
most aggressive environment.
And then we do have to think about environments in
not only molecular chemistry, but the stress and
temperature, I'll touch on that shortly, and then there is
also a slightly heated surface on the drip shield. It's not
quite as severe.
I have a picture showing something about
thiosulfate I'm going to pass over, you can look at that,
and let me now emphasize this or push this analogy a little
bit.
What my hypothesis is here, which I think is a
reasonable hypothesis, is that the surface of the drip
shield is, first of all, going to be hot. We know something
about the temperatures, we can calculate those.
And furthermore, that on the surface of this drip
shield, there's going to be dust, which will form
eventually, it will build up, and this will interact with
the chemistry that's around and eventually we will build a
deposit on the surface and this deposit now will begin to
change the nature of the thermal condition at the interface
and will be -- will approach the analogy of this crevice.
Now, to give you some idea about what happens to a
concentrated crevice, just to give you some reality about
what is actually observed in a steam generator, this is a
pulled tube from Beaver Valley and it shows you something
about the kinds, the extent of the cracking in a
concentrating environment.
Now, the detail what the chemistry, the causative
chemistry has a range that I will discuss shortly, but there
is a reality in the cracking that does occur that you should
appreciate.
Now, the next idea, again, I want to emphasize or
take further is the idea that in the beginning, from the
point of view of thinking about performance, you really do
have to think about the available elements.
And so far as I can tell, from Maury Morgenstein's
work and others, including DOE's, that this is the set of
species in some form that has to be considered, not just
lead. We're talking about a lot of other species. And that
this somehow can find its way to a heated surface.
Again, I realize this is an argument, it's a
hypothesis, but it's a bounding condition that we've got to
start with.
Now, to look at this in a little bit more detail,
I think an approach to thinking about this surface is that
first of all, we have dust deposits. These deposits will
probably harden under the reaction of chemicals.
The surface is going to be hot. This hot surface
will become hotter because of the thermal resistance.
These chemicals are maybe available, and then in
this kind of a structure, we're going to also form sets of
cells which will have alternately hydrolysis and
alkalization effects, and how that will play out isn't
actually all that clear to me.
So that's sort of a place to start thinking about
a structural mechanistic picture.
DR. HORNBERGER: Roger, do you have any guess as
to the time scale for the evolution of this dust layer?
MR. STAEHLE: Well, no, I don't. I mean, I think
that, again, we're not talking about a 40-year nuclear
plant; we're talking about longer times.
And I think the question of dust buildup deposits,
I think once you've been to Chion and seen the dust that
built up on the soldiers, these things happen, you know, and
those of you who are in the rock business probably know that
story better than I do.
DR. SHEWMON: But the heat does decay, and that's
over decades to 100 years.
MR. STAEHLE: Yes, so, if we're looking, say, at a
hundred years, we still have a big thermal resistance here.
I mean, this is not going to go away quite that
quickly. If you look at the DOE -- the
temperature-dependent concentration, they show a peak that's
over 100 years from now.
But I think the problem here is that what -- my
sort of perspective for a model needs some quantification to
it, and that's something that I'm not here to talk about,
but I will eventually.
But I'm portraying something which I think is a
reasonable hypothesis for a model which has, I think --
obviously needs some work on it, including Paul's thermal
thought.
Now, let me show you sort of the general panorama
of a crevice in this heat transfer condition in the steam
generator. What you've got is a hot -- this is 320, 325
Centigrade. Out here it's about 290.
This is the tube wall, this is the tube support.
And what you've got in here is, you've got a two-phase water
steam system; you've got capillarity effects; you've got
deposits; you've got corrosion of this side occurring.
And these species are all available, and then
you've got gradients in the system. You've got
electrochemical potential gradients, temperature gradients,
concentration gradients, fluid density gradients, that do
things that are certainly analyzable, but a little bit
complex.
Now, this is a real crevice. This is from a paper
by Combrade, et al, in 1995. This happens to be a -- this
vertical is a thickness dimension.
This is the location where the tube support is,
and this is outside the tube support. So this tells you the
thickness of the deposit, 100 microns for the outside
deposit.
And simply having thought the water was a fairly
pure water, having quite an array of compounds including
calcium, silicon, or course, iron makes sense, molybdenum,
aluminum, and then farther down inside, looking at arsenic,
antimony, barium, believe it or not, and then some organic
species that will form, presumably because of the carbon
present and the temperature. You may get organic species of
various kinds, and also the hydrazine gives you some
nitrogen.
So, you know, in these heat transfer crevices, a
lot goes on. And this isn't to say it's perfectly
analogous, but it is to say that this kind of complexity
needs to be considered.
Now, I won't cover the stress issue. The stress
issue, at least to me, is pretty self-evident; that in the
mill-annealed surface of the tube in the steam generators,
the cracking occurs just fine.
That rate of cracks I showed were from something
that was not a U-bend. It was mill-annealed surfaces.
So, to me, you really get -- and the stress,
contrary to the DOE thought, is not just at the welds. The
stress is over the whole surface. When you make a metal
surface, you've got to grind it, you've got to bend it,
you've got to do things to it.
And that surface will be stressed unless you
figure out a way to globally heat treat it, and when you
globally heat treat it, you change the metallurgy and you
make a bigger problem.
Now, so I'm going to take the next step and talk
about material deformation. What I've just done is sort of
painted a picture of what I call environmental deformation.
It clearly has some argument to it, but that's a picture.
Now, let's talk about defining the material. Paul
asked a little bit about this during the previous
discussion. I'm going to hopefully answer some of those
questions, maybe.
But the essence of C-22 is that it's prone to be
less stable and neutral to alkaline environments. The
alloying additions are basically additions that are used for
acid resistance.
The second point is that for lack of data, C-22 is
a lot like 600 or a cross between Alloy-600 and 690. I
think these data are applicable to a first order, not
perfectly, but I think that what's available in 600 needs to
be considered.
Third is that there is a very broad range of
effects of metallurgical structure on Alloy-600. We're not
talking about a metallurgical monolith in terms of
composition.
This has all the variability that occurs and
structure property relationships. I'll illustrate those a
little bit.
If we move to global stress relief, we're going to
change the structure and the proneness to corrosion. We
need to pay a lot more attention to grain boundary
composition. I won't say much about that at the moment, but
I think it's pretty obvious.
As far as I know, there is no prototype that's
been fabricated that even tells us what this animal looks
like. And so to some extent, we are kind of talking about
something that hasn't been done yet.
Now, let me give you some metallurgical
perspective, or a an alloy perspective. This is the Ternary
diagram for iron, chromium, nickel. This is iron, nickel,
chromium; this is a 400 C isotherm.
And these are the classic stainless steels, the
410, the 430, the Type 304 stainless, and at least the
stable alpha-gamma region; the Alloy-800, 825.
Now, the alloy we're specifically interested in
comparing with Alloy-600 has been for years, the standard of
steam generators, and now the Alloy 690 is the standard of
steam generators.
The C-22 Alloy fits about right in here, from the
point of view of iron, chromium, and nickel, but in
addition, there is 13 percent molybdenum, some tungsten, and
cobalt, so that, you know, stretches a little bit the
comparison, but this is a place to start.
Now, the molybdenum, tungsten, and cobalt,
metallurgically will affect the precipitation of carbides in
the boundaries, and probably minimize the so-called
sensitization effects that sucks the chromium out of the
grain boundary area. Chemically, I'll talk about that in
just a second.
So I think there's some argument to be made that
the large amount of data that are available on Alloy-600 is
relevant, although may be somewhat imperfect, but it
certainly is a good place to start.
Now, here I'm showing the potential pH diagrams
for the main alloying species in C-22. The main alloy
element is nickel, and what I have in these diagrams, this
lower line is the standard hydrogen equilibrium; this is the
standard oxygen equilibrium; these are all at room
temperature.
And this is the -- this hatching in each case is a
pure metal. The other hatching here is the sequence of
various oxides, depending on the oxidizing potential.
And you can see that, of course, the big advantage
of nickel is not so much the fact that you've got passive
films; it's the high solution potential which slows down the
reactivity.
Now, there is some film here. The film that
actually shows up on these alloys is not so much a nickel
oxide but a nickel-chromium oxide, which as a slightly
broader stability that I'm showing here.
With 21-percent chromium, the CR-203 stability has
this range; it gets it acid benefit from the fact that
phenomenalogically you can extrapolate this CR plus three to
CR 203 line in this direction, and it seems to preserve a
metastable stability and gives you acid protection.
Molybdenum is a largely misunderstood material
from the point of view of corrosion resistance. It's sort
of like, wow, I have molybdenum, therefore, I'm somehow
great.
The fact is that molybdenum is absolutely soluble
in water. And molybdenum is only useful in the relatively
acidic environments and in the very acid environments where
you have a MO3 stability.
And so molybdenum is not a great addition,
especially for neutral to alkaline environments.
Tungsten has a passive range below about pH 3, and
above that range, tungsten is soluble in water. And then
this is the well-known iron diagram which has a fairly broad
alkaline stability, but unfortunately there's no much of it,
and chromium or cobalt looks very much like nickel, and
there's not much of that, either.
So that's kind of the picture, but the sort of
thing you come away with the in C-22 Alloy is the material
is basically a lot like Alloy-600, possibly a little bit
like 690, with chromium and tungsten, but the chromium and
tungsten don't help you in neutral solutions.
So, it's not -- there is some question about it,
okay.
Now, we had this -- I had several questions about
metallurgy. Let me show you two things quickly: This plot
is percent of affected tubes versus heats.
Now, let me tell you what was done here: This
work from Peter Scott at Framatome. The French,
fortunately, know for every steam generator, the heat of
material used in ever tube.
Now imagine the possibility then of taking each
tube that's plugged or cracked and relating it to a heat and
being able to say what fraction of that heat cracked. So
you've got 35 tubes made out of heat one, and, you know, 20
of them crack, then you know that you've got about 65
percent tubes cracked from that heat.
So this is now 40 percent up here, so one heat
cracks a lot, fractionally. There are 25 or 30 heats here
in one steam generator. There are 4,000 tubes in the steam
generator, so it's reasonable there should be several heats.
Several other heats crack at the ten, or
five-percent level, but over half of these heats hardly
crack at all.
This tells us something about thinking about alloy
development; that we need to think about in developing an
engineering framework, about something about the
structure/property relationships and the effect on the
corrosion processes.
This is the induction time or initiation time for
cracking in pure water environments, essentially pure water
environments as a function of grain boundary carbides within
the specified carbon in the alloy.
So, for essentially the same carbon, same nominal
heat treatments, depending on the carbide distribution at
the boundaries and away from the boundaries, there's an
enormous difference in the proneness to cracking.
So this is not to make an argument in too much
detail, but simply to point out that the structure, as those
of us who have been in metallurgy a long time know, is a big
issue.
Let me say just a word about the Grade 7. Grade 7
titanium, for those of you who are unfamiliar with it,
basically has about two to three-tenths palladium in it.
Now, why palladium?
What palladium does, kinetically, is that it
accelerates the reduction of the water, that is, the water
at the hydrogen reduction. That's the so-called exchange
current electrochemistry, and by doing that, it raises the
open circuit potential on the surface and keeps it away from
the low potential range for hydrogen or where titanium has
its greatest vulnerability.
But in terms of our interests here, it actually
hasn't been very well characterized, and I make a couple
points there.
Now, let me tell you a little bit about the
material selection for Alloy-600 as maybe a
history-repeats-itself kind of story here.
Alloy-600 was initially selected, based on its
great nominal corrosion resistance to chlorides, based on a
boiling magnesium chloride test. That was the total basis
for the choice of that material.
This work was first presented in 1957 by Copson,
later presented again in 1959 by Copson, and that's the
total basis for the choice of this material.
Now, it turns out, as I will show you in a minute,
that the failures that have occurred have had nothing to do
with chloride, and not only that, but the basis for using
chloride as a criterion is just wrong, because this alloy
cracks just fine in chlorides; it's just never been studied
very well.
Now, the Alloy-690, the higher-chromium alloy, was
again basically selected based on a 1972 work by Flint of
INCO in the UK, where he showed that this kind of
composition was nominally resistant to cracking in lead, and
also was resistant to cracking in oxidizing crevices. The
detail is not so important here, but I'll show you how in
both case those criteria were fallacious.
These are Copson's data. This is breaking time
versus nickel for a 20-percent chromium composition. The
point is, above about 50-percent nickel, the cracking stops.
Now, 42 percent boiling magnesium chloride is a
fairly aggressive environment. Anyway, so this is not a --
but there is something of a fallacy in using some aggressive
environments, and I think you all know that very well, but
this is a good example.
So these were his data which stood some test of
time for awhile. In 1981, two EDF people, Berge and Donati,
published a paper showing, in fact, that Alloy-600 cracks
just fine at about the same pH with small amounts of
chloride in a boric acid solution with the same
transgranular cracking, and later then published about three
years ago, the full set of data.
But the fact is that what that shows you is this
assumption, presumption, is just wrong, and, second, that
the alloy in service wasn't a chloride problem in the first
place; it was a problem with alkaline cracking, acidic
cracking, lead cracking, low potential cracking, and some
copper problems and so on.
So, the test that was done to qualify the material
was largely irrelevant. With respect to the lead issue in
qualifying Alloy-690, this is chromium concentration versus
iron.
These were exposed to high purity water with a
lead oxide in the environment. And this shows a region of
cracking.
Alloy-600 is about -- this is 18 percent.
Alloy-600 is about right in here. Alloy-690 is up here at
30 percent of chromium, about 10 percent -- this should be
over a little bit, incidentally -- and nominally it was in
the region where lead did not cause cracking.
However, again, I have a photomicrograph here
which some of you metallurgically inclined people might
enjoy. This shows the effect of an aqueous lead
environment, the specimen was exposed in the steam phase
above an environment containing lead oxide in an alkaline
solution of one molar sodium hydroxide solution.
And I don't know about you, but this is the worst
cracking I've ever seen. And this is purely a lead oxide
kind of environment.
The point is that the early work, again, by
International Nickel on this subject, produced an alloy for
which it was just an incomplete evaluation of the
properties.
So, the qualification of some of these materials,
even with extensive testing, is something that maybe needs a
little -- leaves something to be desired.
Now, the third step in making predictions,
corrosion-based predictions, is to figure out what the
framework is for where certain kinds of corrosion occur with
respect to some reasonable variables.
And the variable I'm going to use here for this
discussion, the main framework variables I'm going to use
are pH and potential.
Now, rather than going through this, I think I'm
going to show you the pictures . You can read this. One of
the first very useful frameworks that was developed was
published from the work of Parkinson and Congleton at the
University of New Castle.
This is a potential pH diagram for iron. This is
work that was done in a variety of aqueous environments,
including phosphates and carbonates and nitrates, showing
that there was a range of cracking, essentially along the
axis of the FE-304, FE-203 line; that the minimum in
cracking occurred at the minimum insolubility for the iron
oxide.
And then as you moved to more alkaline, you get
alkaline cracking.
This line shows that below this line, the alloy
cracks again in hydrogen environments, and so what you end
up with is a framework for low alloy steel, which looks
schematically like this.
This is the hydrogen line, the oxygen line, and
these other lines are the main phase ranges for iron
compounds. You have a hydrogen region below this value, you
have an anodic, mildly acidic region here that cracks,
alkaline region here that cracks.
Now, this framework that I'm showing you here, the
results from Parkinson and Congleton's work, actually
applies in the broad range of iron -nickel-chromium alloys
with variations which are more or less slight, and I'll show
you that in a minute.
So it's possible to dope out the framework. I
mean, this is not necessarily magic. It can be doped out.
And let me show you now, something that we
published in 1989 for the occurrence of cracking of
Alloy-600. This is, again, the potential pH framework.
This is a diagram at 300 Centigrade. or calculated at 300
Centigrade.
These are the iron lines; these are the nickel,
plus two, nickel oxide, lines. Now, what I've shown here by
the crosshatching are four regions where cracking occurs, no
unlike what we just saw for the iron.
You have alkaline cracking, and I'm going to show
you in a minute, how well defined this actually is. There
is acidic cracking, cracking of low potential regions. This
used to be called PWSCC, but that meant that it had to be
occurring in the primary system, which doesn't make any
sense, and so I've relabeled this as low potential cracking,
which it really is.
Then there's a high potential cracking range which
occurs in BWRs, and this is the thing that has caused the
cracking in the BWR technology until it was fixed by
changing the alloys.
So, this is essentially what the data tells you.
This is based on real data, where I have actually taken all
the world data and plotted it and come up with these regions
where cracking has actually been observed to occur in this
particular alloy.
Now, to show you that this is, in fact, based on
some pretty solid data, let's take, for example, this
transition here from the cracking region to no cracking
here.
We look at these data from Smialowska, and this is
amount of cracking versus potential, and the change from a
lot of cracking to no cracking occurs about over 100
millivolts, just right about the standard hydrogen line
which also happens to lie at the same place. This should be
NOI right here, how that happened.
Anyway, so, this change from no cracking to
cracking has been very well defined by a lot of people,
which is this situation here.
These boundaries can be defined. The alkaline
region, which is this region here, has also been very well
defined by many investigators. This happens to be
Mitsubishi work for Alloy-690 and 600, showing that the
potential dependence of that region of cracking covers about
300 millivolts and starts essentially at the D-area of open
circuit potential.
So, it is possible then to dope-out the regions of
a given material where cracking does occur. And it doesn't
necessarily have to be all that obscure.
Now, an interesting test, set of tests was done.
I mean, can we do this today on some material? The answer
is yes.
This was a set of experiments that was done by
Mitsubishi and reported in 1994. Again, this is
electrochemical potential versus pH. Actually the reference
here is a horizontal reference.
What the did is, they did a bunch of experiments
and then checked out these regions and so this was a
coherent set of experiments.
You get the same result that I got from patching
together everybody's data.
Now, what I've show here are what I call the major
submodes of cracking. The reasons I call them submodes is
that the principal mode here is a stress corrosion cracking
mode, but a submode really is an occurrence which as
different pH potential, temperature-dependencies. So each
of these has different dependencies. They're still all
stress corrosion cracking.
Now, let me show you then some minor submodes
which are maybe pertinent to this discussion, and I'm going
to show you a region of this diagram here and look at some
minority points.
This is what I call the set of minor submodes
which occur in Alloy-600 and 690. Our discussion of lead,
for example, the data on lead show that cracking due to lead
mainly is lead oxide added to these environments.
And, incidentally, there's this question about
chlorides that's interesting because a lot of this work has
been done down around the pH-3 range, with chlorides and
lead. It cracks just fine.
So the range of cracking of the lead is a little
bit difficult to see, because I've got a lot of stuff on top
of each other. But lead produces cracking that has been
verified over a full range of pH.
In addition, when the sulfur is in some lower
valence form -- don't ask me in detail what it does,
although I published a big paper on this last year -- but
when sulfur somehow gets into a lower valence, a plus-2, a
minus-2 valence, it causes all these alloys to crack fairly
rapidly.
Unfortunately, this work hasn't been extended
beyond the basic region, but it I am sure is an issue over
this whole pH range, of course depending on the stability of
the pH dependence of the stability.
Now there are some other species here that are
important in the presence of alluminates and silicates. the
alkaline cracking occurs at the lower values of pH and the
acid rains, the presence of copper in the environment
accelerates the occurrence of cracking. Chloride produces
cracking we know now in the pH 3 range. This has not been
studied at higher pHs, and so there is an array of sort of
miscellaneous things that people have done that are in
frankly not very great shape but nonetheless are out there.
Just to illustrate one of these, these are data
and it's a little bit complex and I won't bore you with it
too much. This is Alloy 600, Alloy 690. These are in
solutions of varying -- and I have the solution basis
here -- medium acidic environments.
Now the difference here is that one set of alloys
was exposed in autoclaves without copper oxides in the
autoclave and the other with. What does cooper oxide do?
For those of you who know the thermal on this it gives you a
potential that is the thermodynamic potential is about 500
millivolts above the standard hydrogen potential but the
mixed potential won't be that high.
Now they have also added with hydrogen, without
hydrogen. What does hydrogen do? Hydrogen lowers the
potential and so what that means is that without the
hydrogen leaving the potential probably a couple hundred
millivolts above the standard hydrogen electrode it cracks
both Alloy 600 and 690 very rapidly.
Now that is just one of the multiple submodes and
this is due to an acid copper system which we could discuss
later if you wish.
Now the point then I want to make relative to our
discussion, that having laid out what is a fairly extensive
definition of Alloy 600 right here, the question is, okay,
what about Alloy C-22, and Alloy C-22 has no definition at
all.
That is the alloy we are talking about engineering
with. We are talking about engineering with an alloy for
which there really is no panoramic definition. It's not
that there are not some very nice experiments that have been
done. Incidently, some very nice electrochemical work has
been done by Gustavo over here, Dr. Cragnolino, but the
point is that in this alloy that we are talking about
engineering with there is no basis for making judgments
about turning left or right. We don't know where to
engineer with this system.
Now a similar situation occurs in the Grade 7. I
won't discuss that. I have a few notes about the titanium
system, which I won't bore you with since it is not as
important here and let me move on now to some prediction
processes.
If you read the DOE analysis of how they predict
stress corrosion cracking, they essentially use the approach
that has been developed at the GERND, mainly by Andreson &
Ford. They have done a lot of very nice work on this, but
essentially what they come up with is that the crack
velocity relates to the crack tip strain rate and some
environmental exponent.
Then they convert this crack tip strain rate into
a stress intensity to the fourth power so you can substitute
stress intensity in here to approximately the fourth power.
Now the problem is this doesn't predict anything.
It doesn't tell you anything about the environments. It
doesn't tell you about mode diagrams. It just simply is a
way of plotting data and so this is not a basis really for
any kind of prediction nor is it a basis for if you take the
data -- this is work from Eason & Shusto in 1983, this is
their statistical analysis of weld failures in BWRs for
smaller pipes and larger pipes.
The discrimination actually isn't so important
probably and this is one percent failure, tenth of a
percent, hundredth of a percent. There were a lot of welds
in a lot of plants.
This is a Weibull plot. The slope here is a
little bit more than one, which means this is very
dispersed, very dependent on heat to heat variation of the
welds. Something has happening here -- so this formulation
doesn't predict this either, so we need something that is
just a little bit better than saying this is proportional to
something, to a power.
One of the points that's made in the DOE report is
the minimum stress intensity for cracking they find is
around 30 ksi root inches or greater. In fact, in alkaline
cracking the minimum S1 SCC is around 10. It's actually
lower than that, so that assumption I think is somewhat
questionable.
Now the next step, having gotten some sense of
environmental definition and again this was sort of an
argument about what the environment should look like on the
surface when you have a heated deposition. You define the
environment and you define the metals. We have discussed
it.
The next step, a little bit slanted here, is what
I call super position, and what is super position? The idea
is what you do very schematically is you are interested then
in comparing the mode definition -- this is where the cracks
occur, as we show in our mode diagrams -- with the
environment that you have, and I have shown these in
potential pH coordinates. This could be in any
coordinates -- and you find out where the overlap is.
Now the problem here is it means that you have got
to have some definition of mode. Where do these occur? For
C-22 you have absolution no definition of where cracking
occurs despite the fact it's pretty clear that it cracks.
We just don't know where.
With respect to the environment, the idea of
engineering in terms of a aqueous environment from J-13 when
you are thinking primarily about a concentrating surface, it
just frankly is irrelevant, and so the capacity then to make
a judgment about the inner section of modes and environments
I think is maybe somewhat difficult.
Now the next point I wanted to make -- I am almost
done but not quite -- is that the reality, the making
predictions has to be based not on just one set of
experiments that one guy or one lady ran in the lab, but in
fact is the result of work by a lot of people over some
length of time and even though if you don't like the data
and you would rather sensor it and just include your data,
the reality is you have got to deal with a set of data by
respectable people and this -- these are crack growth rate
data versus stress intensity.
This is from a collection by Jansson & Morin, but
the point is the crack velocity versus stress intensity, one
gets down to about 10 KSI root inches. The megapasal root
meter is virtually the same set as KSI root inches, not
quite.
This is what? Five, six orders of magnitude of
crack velocities. Some of this is pretty crappy data.
That's not a technical term, but --
[Laughter.]
MR. STAEHLE: -- but it is, and the same problem
with smooth surface data. I showed these the last time I
was here. They haven't changed very much.
This is time to failure versus 1 over T for
stainless steels and magnesium chloride. These are data
from about 20 different investigators which we have put
together.
I know every one of these investigators
personally. Unfortunately about half of them are dead now,
but what this shows again is that this is the reality of
data for a set which is done by people of some repute, and
so in making predictions we need to recognize that you don't
have the sort of monolithic single value kind of capability
but rather a somewhat more complex circumstances that you
need to pay attention to.
What I would like to do now is just conclude and
say just a few things here that -- this actually is in the
beginning of my notes -- that my first conclusion in looking
into this problem is that there's substantially inadequate
knowledge about the conditions under which C-22 or Grade 7
sustains cracks, i.e., there is no capacity to know whether
we go left or right with respect to an environmental
definition.
Second, I don't think there is any corrosion
testing of a real environment -- that is, the concentrating
surfaces. This just simply doesn't exist.
It is doubtful in my opinion that any of the work
that has been done under isothermal conditions is
substantially useful or substantively useful. There's a lot
of good work that has been done. It's not bad work it is
just irrelevant.
The residual stress issue on broad services is
quite adequate to produce cracking. The application of
global heat treatments to reduce surface stresses may
accelerate other problems. So far there is no evaluation of
the condition of manufactured prototypes. We don't know
what the prototype does in terms of surface stresses.
There is no prototype system for judging real
environments. Nobody has made -- for example, for those of
you who know this, recall in the early years the BWR people
made a quarter size BWR to evaluate certain heat transfer
and fluid flow things -- a wonderful system they had
built -- and the PWR people did equivalent things. There is
nothing like that here. There is no prototype facility that
you can go to.
Again, some of you historically may remember the
A1W and the S1W and D1W things and the whole tradition of
this industry was to build prototypes. There is no
prototype here for the environmental problem.
The next point -- this is the point Jeff made --
that I think there's a lot that can be learned in the
historical sense from looking at some of these analogies and
paradigms from the nuclear development and I am also
somewhat concerned that the same people that said there was
no water present or going to be present are the people that
are now making other predictions.
So maybe with that -- oh, one more thing I wanted
to mention here quickly -- the things that I think are
needed.
First, I think we need to develop a plan or
program or system for realistically testing heated surfaces
and I would be the last one to tell you, as I am sure Jeff
and Ronnie would be, that these experiments in autoclaves
are the perfect experiment. They are not. They just happen
to be a good place to start -- say do you have a problem,
are you worried or not worried, is this a perfect material,
what, and ideally these experiments should be done on heated
surfaces with grips or with something that is a better
approach to reality.
Second, I think we need to investigate this
question about just how much of the Yucca Mountain chemistry
is really relevant. Now I made this sort of bounding
statement that from the beginning you have got to start off
and say what's there, and it will get there. Now that is an
overstatement.
Then you have got to back off and say, well, now
how much of it can get there and how, and let's do some
prototypes and figure out just what really happens and take
some intelligence from the steam generator examples.
There is no mode diagram story for the C-22 or the
Grade 7. You simply don't know how these materials perform.
We need to assess stresses over whole surfaces for
manufacturing prototypes and we need to assess stresses over
whole surfaces for manufacturing prototypes, and we need to
get some kind of a prototype where we can deal with these
large-scale environmental problems. Okay?
DR. WYMER: Thank you very much. That's a lot.
Let me ask you a unscientific question and it is
just a matter of your judgment.
What is the likelihood of getting the essential
information to qualify C-22 in about six years?
MR. STAEHLE: That's why I showed this data from
Mitsubishi -- one chart showing this -- because that was
actually done in a couple of years.
Actually the guy that did most of that works,
former Ohio State guy, which Paul and I both expect --
[Laughter.]
MR. STAEHLE: The work that was done by Parkins
Congleton on their work was done by about four graduate
students over a period of five years, but in fact with an
organized effort I think the things that I think need to be
done here in that kind of time I think is reasonable.
Admittedly there is a problem of acceleration and
predicting, even if we had started the experiment today and
it went six years, there is always the question of just how
relevant is this but of course if it fails in six years then
you have got a big problem with 10,000.
I think that clearly we are not going to get to my
friend Bob Way's aspiration --
DR. WYMER: No.
MR. STAEHLE: -- of defining all the atomistics,
where I think we can get a lot smarter, there's a lot of
thermal around we can deal with. I mean there's a lot of
analysis we can do that I think is pretty intelligent and so
I think that a person could conceive of a reasonable program
in that kind of time to get a reasonable set of data.
I was afraid when we started talking you were
going to ask me about a year --
DR. WYMER: Oh, no.
MR. STAEHLE: -- and I thought, well, I've got a
problem with that, but a six year program done by good
people who have good leadership I think can do a good job on
this.
DR. WYMER: Thank you.
We need to take other questions, even though it is
Noon.
MR. STAEHLE: Sorry.
DR. SHEWMON: Let me make a couple comments.
One didn't come up in the discussion but I am sure
this C-22 was given us by Mike Stryker, who came out of
Dupont and did corrosion work for them for years, which
would fit in and he, when I last was involved in this 10
years ago, was on his horse to save the program by getting
rid of the stainless steel that they were talking about
then, probably a 316 or something and going across to this,
which just didn't stress corrosion cracking or much of
anything else.
I am not sure whether Mike is still with us or
not.
MR. STAEHLE: No, Mike is still around, and Mike
was one of the great people in the field.
His experience I think was basically in acid
corrosion. I mean that is where Dupont had a lot of their
problems.
DR. SHEWMON: The other thing, you raise an
interesting point that you can get lots of concentrations
with high heat fluxes. You talked earlier about getting a
temperature variation. Let me remind you of your original
premise and said it is the heat flux, not the temperature,
so the heat flux does dies down a lot in decades.
MR. STAEHLE: Well, Paul, you are right. It is
against though the framework that in any given day you could
run a crack all the way through this wall in about four,
five hours so we are not talking about -- if you get the
right galactic intersections this is not a great big
challenge to crack and so I think we need to sort of be
conscious of that framework.
The problem here is look, Roger, if you are so
clever what is the answer to this sort of question which I
think is an honest question to ask. The way the problem was
essentially solved in the nuclear technology was of course
by a process of evolution and that Alloy 600 had lots of
problems and eventually the 690 became a better material.
They redesigned the tube supports, reorganized the water
chemistry and so you have a system that behaves pretty well.
In fact, I want to Kansi Electric Power and they
wanted me to analyze the 690 future and I laid out to them
some of the problems that were potential problems and the
manager of the program said, well, you're right. We agree
with you that it has potential problems but in the field it
hasn't failed yet and so we can't justify any work.
Now the point I want to make here is that
basically the solution to corrosion problems is a design
materials interaction. To say that you can solve this
problem totally with one material is just a mistake.
There is not a material that exists today that you
can choose that is not going to crack in some framework of
these environments.
You have got to step back and say listen, we need
to look at this not as a material but as a design material
system so the solution is someplace like that.
This on the other hand means that we have got to
be intelligent about our understanding of C-22 because you
can't design with something that you don't know left, up,
right, or down, so you have still got to do that, but I
think to think that a C-22 is going to resist even the
reasonable environments that you can get there is just a
mistake.
If you go to some other material, well, if you are
so clever, let's think of a better material, I think the
answer is you have looked at some good ones. The steam
generator program has looked at some good ones by some very
good people and you are kind of where you are at.
So I think you have got to accept that reality and
say, look, maybe we have got to kind of rethink how we do
this.
DR. GARRICK: Well, isn't the opportunity even
greater for doing it systematically in the repository
application than it was for nuclear power plants simply
because most of the evolution you are talking about in the
nuclear industry occurred in the first and second generation
plants, rather than in prototypes.
There was some of it in prototypes but most of the
real problems with the BWR occurred after we had BWRs and
they were in operation and during the inspection and
surveillance.
Now in the case of the repository we have anywhere
from a 50 to 300 year operating period.
MR. STAEHLE: Yes.
DR. GARRICK: Which is unique in engineering of
systems, so maybe the opportunity exists to go much beyond
the prototype here and actually have a performance
confirmation program of an actual situation or an actual
waste package under its actual environment and make
measurements there and evolve in such a way that if things
really go bad there is the option of relatively easy
retrievability.
MR. STAEHLE: Well, that is kind of what I was --
I agree with that.
DR. GARRICK: We are not here to design the thing.
We are here to advise the Commissioners on how to reach a
conclusion on its safety.
MR. STAEHLE: Yes.
DR. GARRICK: But I am just picking up on the
comment about the evolution.
MR. STAEHLE: Well, you know, in the nuclear
program there were some interesting early things.
For example, in Dresden, which was the earliest
BWR, they actually saw cracking at room temperature in 1967.
DR. GARRICK: Right.
MR. STAEHLE: And people thought, oh, well, that's
a bad heat. That's always the answer to first cracks -- bad
heat.
The problem of alkaline cracking was clearly
evident in 1967 from Lindsay's calculations where he showed
the concentration of alkalinity in these crevices and from
the paradigms of the stainlesses, the cracking of Alloy 600
was actually demonstrated in alkaline solutions in 1965 by
Sedricks, so little things were out there but they say,
well, that will blow away -- it's a bad heat, something, but
in fact the things that were the beginnings of what
eventually became very big were already known before major
commitments were made. That is one thought.
The second thought is in fact what the nuclear
industry really did was to use the reactors for the model
boilers.
DR. GARRICK: Sure.
MR. STAEHLE: In a sense you can understand all
that in framework of the hurry and the sales and the
competition and all those things, but I think the argument
here is that maybe we need a more stepwise, thoughtful
approach to how to do this, and one of these has certainly
got to be some kind of a prototype. One is maybe a more
design materials interaction that has some reality to it.
There are some elements like that that we ought to
evolve and rather than just saying we have got to have this
tomorrow, we have got to pass a safety thing or an NRC thing
tomorrow, you know, I just don't think that is consistent
with the nature of this system.
DR. GARRICK: My point was that a lot of what we
discovered in the nuclear plant systems came considerably
later, such as the core spray nozzles on the BWRs.
MR. STAEHLE: Right, right.
DR. GARRICK: And I don't think we are in that bad
a shape here in terms of being able to come up with a design
and manufacturing strategy.
That is to say, there is a lot more opportunity
here for doing research than may be the first impression
would suggest.
MR. STAEHLE: I think if we could think in those
terms and a mature view of how things really are in
approaching that, I think this is quite an imminently
accessible, doable thing.
Excuse me, Morrie?
MR. MORGENSTEIN: I do have a concern relative to
this. If we are reading PMRs and AMRs that have start to
failure times at 10,000 years from now for everything in the
AMRs and PMRS no matter what the topic is and it is based on
our C-22 canister.
I am worried that the site as defined as a natural
barrier may not be as rigorous as we originally envisioned
and we are relying very heavily on C-22 as a containment
barrier.
We have pretty much agreed that there's some
problems with C-22. Are we willing to go for the next 300
years and investigate C-22 while loading the repository or
do we need some other kind of discussion?
DR. GARRICK: Well, I don't get the impression
that we need 300 years. I get the impression we can do it
in a much shorter period of time, but I am saying this as an
advantage that they have. They have a lot more time to do
more realistic in-place tests and prototype testing than we
had in the power reactor field.
MR. MORGENSTEIN: I concur. I would like to see
that before we start loading and licensing.
DR. GARRICK: And we have done a pretty good job
there. That is my point.
MR. MORGENSTEIN: My point is that I would like to
see us investigate C-22 before we agree on licensing or --
DR. GARRICK: I think that is correct, yes.
DR. WYMER: Any other comments?
MR. CRAGNOLINO: I have a comment and a question.
My comment regards something that was mentioned in
the past by Roger regarding the fact that we really look in
the resistance to corrosion of Alloy 22 and one of the main
reasons that was not mentioned for the large counting of
molybdenum and tungsten -- they seemed significantly
resistent to localized corrosion and in this sense this
alloy has been used not only for service in the chemical
industry acidic media but on a range of applications for
seawater and the demanding conditions for geothermal
application and a lot for replacement in the oil industry
for perforation and the conditioning -- I mean there are a
series of important aspects that have to be considered.
Roger is however completely right in this concern
about stress corrosion cracking that is one of the most
insidious forms of failure. It is a matter of important
consideration.
We have explored this in our work program, putting
a lot of emphasis in certain aspects. However, I think that
even though the framework that Roger presents in thermal for
pH is very important.
There is one other body of it that should be
included there, and this is my question -- temperature.
What happened with temperature and what happened with a very
large activation energy that this process has in particular
in the pressing of lead for Alloy 600 where we are talking
about 105, 125 kilogen or more.
Roger, I'm sorry, but I would like to ask these
types of questions.
MR. STAEHLE: No, no we are good friends. The
thing -- Gustavo has raised several important points here,
but the actual problem with the answer is in fact that the
data for the temperature dependence is not well established
except over a narrow range.
For example, alkaline cracking of infinel 600
occurs as low as 100 centigrade.
I showed you the data on the chloride cracking
which occurs at 100 centigrade from EDF work.
On the other hand, the cracking of the -- the pure
water cracking and the so-called low potential cracking has
a fairly steep activation energy and a long coefficient in a
sense and probably does not practically occur below probably
at least 200 centigrade and maybe more like 225 centigrade,
so -- but in fact the interaction -- I mean one of the
problems, for example, with this is a lot of the possible
interactions just have not been explored.
Potential dependence -- we had this discussion on
lead dependence -- and I think you have to step back a
little bit and say, you know, if it cracks here we better be
careful of there. It doesn't mean we can't do it. It just
means we have got to be careful to do the experiments and I
think short of having the kind of atomistic things that we
would all like to have, we have got to give things not a
super-wide berth but a wide enough berth to say at least we
do experiments that are intelligent -- I mean but that is a
good point.
DR. WYMER: Bill?
DR. HINZE: Roger, just a very quick question
based upon your experience.
Do you have any comments about the relative
advantages of lower high thermal loading of the repository?
MR. STAEHLE: Well, I think that is certainly --
the model I was suggesting here is sensitive to thermal
loading because it affects the heat flux and the
concentration and the length of time and I think in general
in the system --
DR. HINZE: And also the moisture.
MR. STAEHLE: Yes, and I think whatever you can do
to cut down the concentration on these surfaces is a good
idea.
That affects both heat flux and temperature on the
surfaces and length of time and those all sound like good
ideas in one framework of thinking.
There is a consequence in terms of how the water
moves and the rocks and those things and I think it is not
just sort of my reaction, it is kind of my reaction and your
reaction together.
DR. HINZE: It is a real coupled process.
MR. STAEHLE: Yes, and I think that, I mean this
is one of the wonderful interdisciplinary things where we
both speak the same thermodynamic language. We both speak
the same framework, but there's a lot of differences in how
we see things and understand things and there is certainly
room for a lot of interaction here.
DR. WYMER: Anything else?
[No response.]
DR. WYMER: Well, if not, this is has been a great
session from my point of view.
It's been very enlightening. We have a lot yet to
do but ostensibly we can do it, so with that I do thank you
all very much. We are adjourned.
DR. GARRICK: I want to indicate that we
anticipated that this might overrun a little and so we are
going to make arrangements to delay the start of the first
session this afternoon on entombment.
We are going to try to do that at 1:30 rather than
1 o'clock as shown on the agenda.
With that, we will adjourn for lunch.
[Whereupon, at 12:17 p.m., the hearing was
recessed, to reconvene at 1:30 p.m., this same day.]. AFTERNOON SESSION
[1:34 p.m.]
DR. GARRICK: I'd like to call the meeting to
order. We're now going to get into the decommissioning
business.
This is Ray Wymer's big day because he's also the
lead member on this, so, Ray, do you want to introduce the
subject and speaker?
DR. WYMER: Yes, we're going to spend an hour till
2:30, so you've got your full time, practically, on looking
at entombment as an option for decommissioning reactors.
Entombment is sort of, as I understand it, has been added
formally to the SAFESTOR and license termination suite of
means of getting out from this reactor responsibility.
So, Stephanie Bush-Goddard is going to talk to us
this morning about the rulemaking activities associated with
entombment of power reactors.
Stephanie.
DR. GARRICK: Except that it's afternoon already.
DR. WYMER: Time flies when you're having fun.
MS. BUSH-GODDARD: Good afternoon. As he said, my
name is Stephanie Bush-Goddard. I am the Task Leader for
the entombment rulemaking.
I am here because the Commission has requested the
staff to consult with the ACNW on this issue. So my goals
or my objectives today will be first to give a regulatory
history.
Entombment falls under -- is a decommissioning
alternative, so I'll talk about the regulatory history of
decommissioning, and then I will go into what actually is
entombment, and some of the specific NRC activities related
to the entombment issue.
I'll go into the need for rulemaking and its
scope, and I'll also give you a current status of where the
rulemaking effort is, and then finally, I'll end up with
some of the guidance I'm asking for from the members.
As I said, entombment is a decommissioning
alternative. It falls under the decommissioning rule in 10
CFR 50.82. And basically this rule says that you have 60
years from permanent cessation of operations to
decommissioning.
The NRC will approve beyond the 60 years, only
because of public health and safety. Now, this rule was
written in 1988. At that time, we only had an unrestricted
release criteria.
That criteria was 25 millirem a year. Then in
1997, we published what you call the radiological criteria
for license termination. This also gave a restricted dose
criteria.
You could -- the criteria was 25 millirem a year,
and if institutional controls failed, you could go up to 100
millirem a year, and if justified, up to even 500 millirem a
year.
However, if you go up to 500 millirem a year, you
had to monitor the decommissioning site, and there had to be
surveillance every five years.
So, let's go into entombment. Entombment is a
decommissioning alternative, and basically it's where
radioactive contaminants are encased in a structurally
long-lived encasement such as long-lived materials such as
concrete.
The structure is maintained and surveillance is
carried out until the radioactivity decays to levels -- I
have permitting unrestricted release here because this rule
was made in 1988 with the decommissioning rule, but now we
also have the restricted release criteria, and that's
something to keep in mind.
DR. HORNBERGER: Stephanie, just a point of
clarification.
MS. BUSH-GODDARD: Yes?
DR. HORNBERGER: Who does the surveillance?
MS. BUSH-GODDARD: The licensee.
DR. HORNBERGER: So is the NRC involved
afterwards, in a restricted release with surveillance or
judging whether the surveillance is successful?
MS. BUSH-GODDARD: In the license termination
plan, I believe, the licensee has to prove that after the
facility is terminated, that they will be able to maintain
either the unrestricted or the restricted release criteria,
and this is even before the final license is terminated.
So, in 1997, when the license termination rule was
being published, the NRC also told the Staff to see if
entombment is viable, and if they determined that it was
not, to see what could make it viable.
So we published this information paper. I'm going
to talk a little bit about that.
After the paper was published, we had public
workshops, and actually we had a public workshop, and we
submitted the workshop findings and Staff recommendations in
a SECY paper.
From that, the Commission told the Staff to
proceed with rulemaking, and I'll go over each of those.
The first was a PNNL report, the Pacific Northwest
National Laboratory Report, and basically they first talked
about some entombment experience in the U.S. Currently, we
have three DOE reactors that are entombed.
They were entombed around the 1969-1970 timeframe,
and they were entombed by regulations under the AEC. These
were small demonstration power reactors.
The Hanford site is also going under some type of
entombment. They have eight former plutonium facilities,
and as we stand now, they're doing partial dismantlement,
and, subsequently, entombment.
Now, the Hanford site is different from the DOE
site in that they have characteristics similar to commercial
power reactors, in that I think they're near a large body of
water, they have low population density, and the residual
activity is more like commercial power reactors.
The PNNL report also did a study, not necessarily
an isolation assessment, but what an isolation assessment
would have to be done if a reactor would be entombed.
Basically you have to look at the radioactive inventory.
Now, they reference a pressurized water reactor
that's about 350 megawatt thermal, and what they said is
that you really have to have a great radionuclide inventory.
If you're only going to leave in the Cobalt-60, which has a
half life of about 5.27 years, then the radioactivity will
last as long as the structure would be able to maintain it.
If you have something like Cesium-137 at 30 years,
and I think Nickel-63 at 100 years, you need something on
the order of 130 to 300 years. And then if you have your
longer-lived radionuclides, I think, like Niobium, that's
like 20,000 years, and then you couldn't necessarily verify
that the containment would last.
They also looked at the transport through the
containment, and the long-term integrity, and they came up
with the conclusion that concrete can last about on the
average of about 500 years.
Now, this report was taken in 1993, and they took
data from the 80s, and they also looked at dispersal through
the environment, in that once the radioactivity left the
containment structure, what type of flow and what type of
pathways would it have to go through?
And they came up with conclusions. First of all,
there is no current isolation data, so you would have to do
a study, and it would probably have to be site-specific on
things like determining distribution coefficients and things
like that.
But the performance assessment could be similar to
the low-level waste disposal -- a low-level waste disposal
facility. So you could take some Part 61 requirements and
apply them to the performance assessment.
Did you raise your hand, sir? Okay.
Also, there is a difference. The performance
assessment could be similar to low-level waste facilities,
but there is a difference between entombment and low-level
waste, in that the source term is very much different, and
the site characteristics could be different.
They also did two types of entombment scenarios.
Say, if you had immediate entombment where you take out all
of the stuff in the beginning and in about five years you
seal and you monitor it until 130 years, and they're
assuming that at 130 years, you meet the unrestricted
release criteria.
Now, this would have to take all the spent fuel,
the GTCC out, basically everything except the Cobalt-60.
And then they also did a deferred entombment where you place
it in storage for 100-120 years, let things decay, and then
entomb.
And from that data, they came out with here I have
radiation dose. If you do immediate, delayed entombment and
to other decommissioning alternatives which are DECON and
SAFESTOR.
Of course, with DECON you have the higher amount
of person-rem, because you're decon'ing the material, the
equipment, but you also have a large generation of low-level
waste here in the red.
Immediate entomb -- and both of the entombed
produce the lowest person-rem here, and they are, each of
them except DECON, had similar low-level waste being
generated.
Okay, so from that PNNL report, the NRC conducted
a public workshop. This was in December of last year. We
took the workshop findings and Staff recommendations to the
Commission.
And I'll go over the workshop findings. In that
workshop in December, the first thing that they found was
that no attendees challenged the capability to construct a
viable, technically-viable entombment.
And we had seven states represented. They viewed
entombment favorably, but an issue that they had is that if
the license is terminated, then the responsibility might
fall back on them. I'm sorry, if the license is terminated,
and if there was entombment failure, that the cleanup and
mitigation might fall on the states.
There was agreement that the Low-Level Policy Act
was not working, and entombment seemed viable from an
economical standpoint.
They preferred excluding, rather than Class C
waste. They felt that if this was going into rulemaking,
the GTCC issue might hold up the entombment option.
And they also called for a need for a study
specific to NRC-licensed facilities. As I mentioned before,
the entombed reactors are basically DOE reactors, in that
the source term is lower than some of our commercial power
reactors.
From those workshop findings, the Staff
recommended that we do an Advance Notice of Proposed
Rulemaking, an ANPR to solicit comments in a regulatory
framework, you know, to get public comments, to get
Agreement State comments and what have you.
So in that Staff requirements memorandum, the
Commission told us to do a couple of things: First of all,
they did not object to a rulemaking plan. They told us to
coordinate the rulemaking plan with the generic
environmental impact statement, and to address the issue of
greater than Class C waste.
The workshop findings said we should not include
that issue, but they wanted us to put it back in, and
finally, why I am here today: To ensure that you all are
appropriately consulted.
So, now we're at the rulemaking stage. I have
here, going from current requirements. What we plan to do
is put the current requirements in the rulemaking plan, try
to provide different entombment option scenarios. I'll go
in that in a minute.
And then specify what we feel is our preferred
option.
As I also said, we're issuing an Advanced Notice
of Proposed Rulemaking, and here we just are telling the
public about the issues, the background of entombment, and
asking questions related to state issues, questions about
the technically-viable issues, the greater than Class C
waste, and what have you.
So, we have a couple of options: The first one is
just to maintain the status quo. We also have to put that
in for NEPA analysis.
A second option is to terminate the license,
amending the 10 CFR 50.82. You know, we have the six-year
requirement, and maybe modifying that requirement to make it
feasible for some power reactors.
And then also we're thinking about retaining some
type of license, maybe under Part 50, or under another
existing Part. You know, Part 50 is the utilization of
power reactors, and the power reactor now will be
decommissioned.
Or we are thinking about some other option, maybe
introducing a new Part under a new regulation, something
maybe similar to the Low-Level Waste Part 61 license,
similar in performance.
DR. HORNBERGER: Stephanie, let me ask a question
to try to overcome some of my ignorance here. So,
maintaining the status quo, just means that you would go on
a case-by-case basis; that is, a licensee could apply for
entombment and you would do the evaluation, and either
approve or not approve?
MS. BUSH-GODDARD: Yes, but that's not viable for
most entombment scenarios. Most reactors have things in
there that would let -- that you could not meet the license
termination rule in the 60 years.
Now, say, if they wanted an exemption, the
Commission will only approve an exemption for public health
and safety. So if you wanted to extend it to, say, 100
years based on economic reasons, as the rules are written
now, you cannot do that.
DR. HORNBERGER: I see. Okay, and the second
option, terminate the license, I'm not clear what that
means.
MS. BUSH-GODDARD: Okay
DR. HORNBERGER: Terminate the license for a
specific --
MS. BUSH-GODDARD: Okay, the difference between 1
and 2 is that you're terminating the license eventually, but
in Option 2, terminate the license, we would amend that
60-year requirement.
DR. HORNBERGER: Oh, I see.
MS. BUSH-GODDARD: Yes. Sorry about that.
So, ending with the other, like I said, it might
be under a new regulation.
So, the current schedule, right now the rulemaking
plan and the ANPR are in NRC Office Concurrence.
Hopefully, by next Friday, we'll send them to the
Agreement States for comment.
That will take about 30 days. We will get the
comments back, analyze them, resolve the issues, send out
another Office Concurrence, and hopefully by that time we'll
also have our paper from you guys, and then we'll send it to
the Commission.
Now, there are some issues, particular issues that
we would like to talk about, however, please feel free to
write down anything you feel would be relevant.
The first one is this issue of dose reduction
credit. Basically, there are some -- we're struggling.
When I say "we," the Working Group is struggling with this
issue of what dose reduction credit can be given for
engineered barriers in an entombed structure.
Basically, how long can we say the concrete will
last? Of if it's grouted and concreted, is there a specific
lifetime we may say that the grout remained -- will remain
effective to meet the dose criteria, which, again, is the 25
millirem a year, the 100 millirem, or the 500 millirem a
year.
And then the second big question is, what should
be the regulatory framework? If we do decide to go with an
entombment option, should it be still under Part 50 and just
be a decommissioning Part 50?
Should we develop a whole new Part and have the
performance assessment similar to low-level waste, do some
isolation assessments and things like that, and have that
criteria in the rule?
Or should it be under existing and existing Parts?
So those are the two questions that we're wrestling with,
we're struggling with.
We would appreciate your comments, and any other
comments that you will have. And that's it.
Are there any questions?
DR. WYMER: Thank you very much. Are there other
questions around the table?
DR. GARRICK: I was a little -- I was trying to
figure out the real merit of deferred entombment, as you
have described it, safe storage to 120 years. Why the
choice of that particular --
MS. BUSH-GODDARD: I guess, from an occupational
exposure basis, that it probably has more merit than, say,
immediate entombment.
DR. GARRICK: And it seems then to go to a sealed
entombment for another ten years, that seems a lot of work
for a short period of time.
DR. WYMER: There is a technical factor here,
Stephanie, if I can jump in?
MS. BUSH-GODDARD: Go ahead.
DR. WYMER: To plot the radiation level inside the
-- from the vessel, that is a function of time. There is a
sharp-kneed curve that's like a hockey stick and at about 70
years, it breaks very sharply.
MS. BUSH-GODDARD: And also this is some -- this
is the PNNL report that they just made up two different
scenarios. I don't think in the rulemaking plan stage,
we're actually looking at, you know, when will the license
be terminated, and even actually look at the different
scenarios of where it would be a delayed versus an
entombment scenario, and even if we would be that specific
in the regulations.
DR. GARRICK: How much has risk perspective been
built into the entombment approach?
MS. BUSH-GODDARD: Well, we're looking at RCRA,
the Resource Conservation and Recovery Act law. They give
some type of risk reduction credit to their institutional
controls, so we're trying to look at their model to see if
we can apply some of that to commercial power reactors.
DR. GARRICK: The other thing is, what are the
specifications for entombment beyond radiation?
MS. BUSH-GODDARD: Specifications beyond
radiation?
DR. GARRICK: Are there area limitations? Are
there structural integrity requirements? What drives the
qualification for entombment beyond radiation levels?
MS. BUSH-GODDARD: We're looking into that right
now, but I can say that in looking into that we are trying
to model some of the low-level waste criteria. I think
we're maybe trying to, if these options -- once we get a
preferred option, we're going to look at maybe putting
requirements in that if you're below a certain water table,
you can entomb your structure.
DR. GARRICK: Is there an area limitation?
MS. BUSH-GODDARD: No, not yet.
DR. GARRICK: Or height limitation? No spatial
language?
MS. BUSH-GODDARD: We haven't developed that yet,
no. We sure haven't.
DR. GARRICK: Okay, thank you.
DR. HORNBERGER: Stephanie, I have a couple of
questions on the same study that John started on, and the
immediate entombment versus delayed.
And in their PNNL, it also had a SAFESTOR option.
Does that mean safe storage in perpetuity? Is that how the
analysis was done? I just thought it was odd to contrast
SAFESTOR with decommissioning and entombment, which seemed
to me to --
DR. GARRICK: Yes, I was trying to relate it why
on earth would you not SAFESTOR through the whole period,
rather than --
MS. BUSH-GODDARD: Well, actually, entombment, if
you can look at it, it can kind of encompass the SAFESTOR
issue.
DR. GARRICK: Right.
MS. BUSH-GODDARD: In SAFESTOR, I think the end
point was to, after the dose has been reduced, to take that
and put it into an existing low-level waste depository, so
to move it away from the site.
The difference between SAFESTOR and entombment is
that in entombment you're having onsite disposal of that
waste.
DR. HORNBERGER: I see, okay, okay.
MS. BUSH-GODDARD: Yes.
DR. HORNBERGER: I missed that. That's, again, an
indication of my ignorance of how this works.
So, again, Ray's point was that of course, if
you're doing entomb immediately, the radiation, the
occupational exposure is higher because you're doing work
inside the containment.
And yet the PNNL study, the difference is between
800 person-rems and 300-plus-person-rems. It doesn't look
like a huge difference in exposure.
DR. WYMER: One of the things that came out of the
conference we attended last week was the fact that the
business of just waiting is one that's being seriously
considered. The British are saying, let's wait 75 to 135
years or something like that, and the Canadians say you're a
little bit out of your tree; we ought only wait about 50
years.
At any rate, they agree you ought to wait, maybe
seven years till you come to the knee in the curve.
So there are definite benefits to those, waiting.
DR. HORNBERGER: I mean, that stands to reason
because of the nuclides there. Stephanie, I think I heard
you say that the PNNL report suggested that concrete will
last 500 years?
MS. BUSH-GODDARD: Yes, they reference another
paper, and in the workshop, it was brought up that it could
last much longer than that. But I'm just --
DR. HORNBERGER: So going to the question, the
first question that you posed that you'd like some feedback
from us on is the life of, the potential life of engineered
barriers. You're just looking for us to again comment on
that?
MS. BUSH-GODDARD: Yes, just comment. You know,
in the end, we will probably do an assessment of different
types of concretes, and they will probably -- I'm not a
geologist or a geological engineer, but go through all these
criteria, and take data from that and decide.
So, just a general feeling of if dose reduction
credit should be taken.
DR. HORNBERGER: Should be taken. Finally, I just
have two other things, again related back. Part of what I'm
trying to grapple with, not knowing too much about 10 CFR
Part 20, Subpart E, but we heard a lot about West Valley
yesterday, and, of course, they're grappling with the
potential use of the license termination rule there, and the
policy statement.
And this issue of surveillance, let me come back
to that.
MS. BUSH-GODDARD: Okay.
DR. HORNBERGER: You said under the regulations,
surveillance would be carried out by the licensee; that's
the licensee's responsibility.
But I guess who looks over the shoulder of the
licensee when they're doing their surveillance?
MS. BUSH-GODDARD: The licensee has to have an
approved plan before its terminated.
DR. HORNBERGER: Right, so they come to you with
an approved plan, and you say, yes, this looks good. The
end then? We just trust them?
MS. BUSH-GODDARD: Well, no we don't. I think
that's when, say, for instance, if we have some type of
failure, then maybe one of the federal agencies, probably
the EPA, would have jurisdiction in that.
MR. LIEBERMAN: Stephanie, could I add something?
I'm Jim Lieberman from Office of General Counsel.
Under the license termination rule, when we're
dealing with a restricted release, the Commission makes a
determination based on the institutional controls that the
cap, the dose cap, if institutional controls fail, is below
either 100 or 500.
They terminate the license when they're satisfied.
If, after that point, something occurs, such that there is a
greater dose, the Commission has said in the regulations,
they will only get involved if they perceive significant
threat to the public health and safety.
They haven't defined in the regulations or the
statements of consideration, what that threshold is of
getting involved because they are seeking finality. But
they reserve the right to get reinvolved to deal with the
situation.
I presume somewhere in the 500 millirem --
somewhere between 100 and 500 millirem, the Commission would
probably get reinvolved.
Absent that, under the decommissioning plan that's
approved and the institutional controls, it provides for the
monitoring, the maintenance, and the surveillance.
And they have to have enforceable requirements but
enforced outside of the Commission's activities.
DR. HORNBERGER: Okay, so who looks at the
surveillance data, and who then does the enforcement? I
guess that's my question.
MR. LIEBERMAN: Okay, it would not be the
Commission, so that would be the state, whoever is the
steward, maybe the state or the Federal Government.
DR. HORNBERGER: And the steward would be
specified in the application for license termination?
MR. LIEBERMAN: Exactly. We have to approve the
steward. We have to be satisfied that there is sufficient
financial assurance, and that the relationship is
sufficiently enforceable so that it will be a workable
system.
In most of these cases involving the large
exposures, potential exposures, they have to have durable
institutional controls which would be more likely the
governmental entities.
DR. HORNBERGER: Okay, so it gets specified, and
that makes sense to me now.
The other thing that I was interested in was that
you mentioned that under the LTR, the exemptions beyond the
60-year period can only be for reasons of public health and
safety.
And as far as you know, that could have a fairly
broad interpretation, though, couldn't it? I mean, I guess
what I'm trying to grapple with is, in your case, suppose
the analysis came back that deferred entombment which went
beyond 60 years for reasons that Ray was saying,
substantially would reduce both occupational and potentially
dose to the public.
Wouldn't that be a reason for public health and
safety?
MS. BUSH-GODDARD: I will -- since OGC interprets
the rule, can you give us an answer to that also?
[Laughter.]
MR. LIEBERMAN: That is a very good question. In
fact, we're looking at that question.
The rule itself, I don't have the rule in front of
me, but the rule says something like the Commission --
approval of the Commission extended, based on a case-by-case
basis, based on health and safety. And then it has some
examples.
And I think one -- can you just read the rule,
Stephanie?
MS. BUSH-GODDARD: Yes.
MR. LIEBERMAN: This is 50.82, .83.
MS. BUSH-GODDARD: Okay, factors that will be
considered by the Commission in evaluating an alternative
that provides for completion of decommissioning beyond 60
years of permanent cessation of operations includes:
Unavailability of waste disposal capacity and other
site-specific factors affecting the licensee's capabilities
to carry out decommissioning, including presence of other
nuclear facilities at the site.
MR. LIEBERMAN: So we're still struggling with
what those words actually mean. So I really can't give you
a more detailed answer.
DR. GARRICK: If you're struggling, what's that
mean about the rest of us?
[Laughter.]
DR. HORNBERGER: So you're not surprised then that
we're struggling.
MR. LIEBERMAN: Exactly.
MR. LEVENSON: I have got sort of a followup
question: You said that the licensee is responsible for the
monitoring, imposes the LTR. But the draft policy statement
on West Valley specifically states that the responsibility
for the monitoring is not the licensee's, but will be a
responsible government entity.
Is that at variance with what's done in power
reactors?
MR. LIEBERMAN: No. During the period the license
is in effect, it's the licensee.
After the license is terminated, it's the function
of the termination plan. You have to have in the case of
West Valley, because of the size of the source term, durable
institutional controls, which the statement of consideration
addresses as basic federal, state, or governmental agencies.
This is a very complex rule, so let me try to
explain it a little bit here. You have to have
institutional controls.
You have to have an independent third party to
provide the monitoring, provide the capability for
monitoring and maintenance.
The licensee can do it, but if the licensee fails,
then the independent third party gets involved, which would
be the institutional controls that would be the federal or
state agency.
So, one scenario is, the licensee does it from
scratch, and that would continue until there is a failure
and then the institutional controls kick in.
Another situation might be the licensee gets out
at the very beginning, and the institutional controls would
begin early on.
MR. LEVENSON: Is the identification of the
responsible government entity something that is done in
advance then, when the -- I can't say when the license is
terminated, because West Valley license is already
terminated.
MR. LIEBERMAN: No, no. The West Valley license
is in suspension. It's going to be reinstated once DOE is
completed.
But in a typical case, yes, it is agreed to in
advance, because we want to make sure that the Government
agency, whoever is going to do the institutional controls,
will agree to do it.
It has -- and satisfied the financial resources to
achieve that, have been set aside in a trust or whatever.
So that when we're closing the site and terminating the
license, all these loose ends that we're talking about are
resolved.
And that may be easier said than done, and we
haven't yet released a license under restricted release.
But several licensees are getting into that
situation now.
DR. WYMER: Thank you. Is that all, George, that
you had?
DR. HORNBERGER: Yes, thank you.
DR. WYMER: I have one question: We may, in
deciding to respond to this, to comment on something having
to do with greater than Class C waste, Stephanie, and this
whole issue of whether or not you address greater than Class
C waste now or put it off into the future sometime, as has
been suggested by some of the people who have made comments
on it.
That brings it up as an issue. Can you say a
little bit more about the implications of deferring the
removal of greater than Class C waste and what this has to
do with the regulation, how you respond to it?
MS. BUSH-GODDARD: There is another
interpretation, and I'm going to have to call you up here
again, Jim. It's the issue that if we include greater than
Class C waste in the entombment structure, we can do what
they call volume-averaging, and if we volume-average it,
then we can classify it as less than greater than Class C
waste, and we can put it in the entombment structure.
If we cannot classify it as less than greater than
Class C waste, then to put it in an entombed structure as
greater than Class C waste would require modifying the
Low-Level Waste Policy Act, I believe.
DR. HORNBERGER: Don't go there.
[Laughter.]
MS. BUSH-GODDARD: Exactly.
DR. HINZE: It sounds like a good idea to me.
MR. LARSON: Remember, this was one of the
considerations in the Trojan Pressure Vessel disposal.
DR. WYMER: And there is the -- 94 problem that
you have, so that it never goes away. It seems to me that's
a pretty significant barrier to entombment, because it's
forever a restricted release.
DR. GARRICK: Sort of as a followup to why we're
where we are on this issue, where has the initiative for
entombment come from?
MS. BUSH-GODDARD: Well, back in 1998 when the
decommissioning rule was written, they gave basically three
alternatives, DECON, SAFESTOR, and entombment.
In the supplementary information, they did say
that they favored both DECON and SAFESTOR.
Now, since we have the license termination rule
with restricted release, some licensees might say, well, we
probably can entomb and meet the restricted release
criteria, hence the new involvement in entombment. That's
kind of the basis why it's being renewed.
DR. WYMER: It's a cheaper option than taking it
all offsite.
DR. GARRICK: I guess you got some feedback at the
workshop as to the public's reaction to the entombment
option?
MS. BUSH-GODDARD: Yes. Like I said, there were
seven states represented. And they looked favorable,
because one reason they realized that the Low-Level Waste
Policy Act was not working, and they didn't know where they
would put the low-level waste.
But there was also a concern, like I said, that if
the license terminated, who would assume cleanup and
mitigation expenses and liability if there was a failure.
Licensees would like to have entombment as another
decommissioning alternative that will give them a little bit
more flexibility in how they're decommissioning.
DR. WYMER: Can you give us a little feeling for
-- do you know how many utilities are considering
entombment?
MS. BUSH-GODDARD: No, I don't. In the workshop
-- right now I know of only one. I think that's Florida
Power, but that's not to say that there aren't more.
But I don't think I have that data, but I can get
that to you, if you'd like.
DR. WYMER: It would be interesting. It didn't
sound like it was a groundswell of the utilities, does it,
to go to entombment?
DR. GARRICK: Well, no. But the utilities have
been kind of frustrated on where to put the low level waste,
so it solves that problem to a certain extent.
DR. WYMER: There's a representative from NEI that
maybe would present the industry perspective on this, if
you're interested.
DR. GARRICK: Yes, that would be good.
MR. GENOA: Thank you, Mr. Chairman. My name is
Paul Genoa. I'm a Senior Project Manager at the Nuclear
Energy Institute, and one of my issues -- all of my issues
involve material disposition.
And one of them is the entombment option. The
industry is interested in entombment as an option.
At the workshop, we had members of our Task Force
On License Termination. Those members represented over 30
reactors that all said at that meeting, that -- well, they
showed up in December in D.C. for a meeting to show that
they are interested in the option, but not that they're
ready to move forward.
I believe the Commission was motivated to pursue
exploring the issue by a letter sent from the State of
Florida. It was a joint letter from the Department of
Health Services, if that's the right term Florida, but the
Agreement State agency, combined with the Public Utility
Commission, both showing interest in the entombment option.
But there are others as well, and clearly, as you
point out, the concern over future availability of disposal
-- we want to understand today, what it will take to safely
disposition these reactors after their useful life is done,
if we're forced to be in a situation where disposal is not
available.
As you know, spent fuel is facing that today. And
there is no regulatory structure in place to deal with that
crisis -- Yucca Mountain.
And so we don't want to be in the same situation
with low-level waste.
Further, there are economic and occupational
safety issues. Right now, in Connecticut Yankee, they are
segmenting the reactor internals. They're removing the
greater than Class C material.
It is a horrendous radiological exposure, about
140 man-rem are being expended today to cut that material
up, plus a lot of other industrial safety issues to involve
in a task that great.
I think you gentlemen have reviewed what happened
in Trojan, and I think any real valid environmental
assessment would find that the environmental impacts of
taking this material out of a very robust container, perhaps
have not been fully evaluated.
Entombment seems to provide some options.
DR. GARRICK: Are we going to run into the same
problems with entombment that we've run into with the states
and the public that we have with the low-level waste
Agreement State compacts? Has the NEI done any surveys or
public outreach projects to get a better assessment of how
this option would be received by them?
MR. GENOA: We certainly have not done anything
formal, but when we look to implement the Low-Level Waste
Policy Act, or the High-Level Waste Policy Act, our
opponents say leave it where it's stored.
So we're looking for a regulatory approach at
leaving it where it's stored.
DR. GARRICK: Near where the sites might be.
MR. GENOA: Generally not, actually.
DR. GARRICK: I guess we can't guarantee that we
won't have the same problem with the entombment.
MR. GENOA: I think that's an accurate assessment.
DR. GARRICK: Right, right.
DR. HINZE: John, thinking back eight, ten years,
the Committee spent a good deal of time discussing the
longevity of concrete.
And, in fact, I think we may even have a letter
that discusses that. You might want to go back and review
those topics and what was said and some of the germane memos
and so forth.
DR. GARRICK: Yes.
DR. HINZE: There is a good deal of information
residing on that point.
DR. GARRICK: Thank you, thank you for reminding
me.
DR. HINZE: The author is here of that letter.
He's not going to admit it.
[Laughter.]
DR. GARRICK: We don't want to press that too far.
Marty, yo had a question?
DR. STEINDLER: Let me just make a comment: It
seems to me that the long-lived activities essentially are
all in the reactor vessel. The rest of the stuff can be
packaged, if you can get it out of there, and shipped to
some low-level burial ground. At the moment, a lot of this
junk ends up in Utah.
So the issue, it seems to me, is not a waste
disposal issue, nearly as severely as one would believe.
The expenditures, as I think you pointed out,
George, the expenditure of over 150 or even 200 person-rems
to cut up a reactor vessel is to the industry, probably a
significant issue, as it should be.
But I would expect that it's a lot more expensive
than filling up a reactor vessel plus its surroundings with
concrete and letting it sit there. So there's an economic
issue.
I think the waste disposal issue is -- my sense is
that it's not real in the sense that there are currently
ways of alleviating that, albeit expensive. If somebody in
the East Coast wants to get rid of a reactor, they've got to
move a lot of concrete debris to Utah, which can't be cheap.
DR. GARRICK: Yes.
DR. HORNBERGER: Not only expensive in dollars,
but if you talk about real risk, the trucks running concrete
pieces to Utah run over people
DR. STEINDLER: Even if it's railroads. And it's
the regulatory nightmare that everybody has got to jump
through.
But I don't see how in the absence of addressing
the greater than Class C issue, I don't see how you can make
this work unless you operate on what I consider to be
numerology, and that is averaging the total waste content
from the fairly hot pressure vessel and piping over a very
large concrete enclosure. Something interesting, but not
really the way it was designed. Dilution is not really
allowed, usually.
But the --
DR. WYMER: It's not exactly dilution, Marty.
That's sort of a fictitious dilution.
DR. STEINDLER: Well, yes, that's right. But you
do have to run some kind of a performance assessment to
address the question of what happens? Supposing your
concrete last 1,000 years on a good day, but in the acid
rain that the Chicago area occasionally comes through with,
for example, 1,000 years is as optimistic as all get out.
Then what do you do with a reactor vessel that's
got a fair amount left of Niobium and nickel? So some
performance assessment has to address that issue.
DR. GARRICK: Yes.
DR. STEINDLER: It seems to me that that should be
the determinant.
DR. HINZE: You might also want to consider some
site characterization, because talking about Florida, you
have your potential for very fast pathways. We saw that
when we looked at the low-level waste siting in that state.
DR. STEINDLER: Yes. The thing that troubles me about this
particular approach is that this is almost setting aside of
what I guess I would call the normal approach to risk
assessment, the business of, the specialized business of
getting rid of a reactor.
I think the regulations have to be more coherent
than that in the overall.
DR. WYMER: Can you address the Maine Yankee case
in this context of their planning to leave something below
grade there. Aren't they?
MS. BUSH-GODDARD: Yes. I think -- I'm not an
expert in it, but I know that they are decommissioning, and,
yes, they do not have a place yet for their spent fuel, or
-- I'm sorry, you said they're planning on leaving something
below greater than Class C?
DR. WYMER: I think I remember from the conference
that they were going to go down to three foot below grade
and leave everything lower than that there; is that right?
MR. WEBB: Yes, Stephanie, maybe I can help a
little bit.
MS. BUSH-GODDARD: Please.
MR. WEBB: My name is Mike Webb, and I'm the NRR
Project Manager for Maine Yankee. And as you've said, what
they have proposed is to remove all the radiological
material above ground level, down to the three-foot level,
to retain the foundations in place. They will scabble
and/or otherwise remove surface contamination, but then
they'll backfill that space with clean soil.
DR. WYMER: That's not exactly entombment.
MR. WEBB: Correct. They will have removed large
portions of both concrete and all the other debris, the
metals that would be associated with entombment.
DR. GARRICK: Marty?
DR. STEINDLER: Just one other thing: This PNNL
report by Smith and Short, there's a disclaimer by the NRC
Staff in the front of it, which I thought was appropriate.
Then I read in the front that this report dated
May 11th, was revised by Carl Feldman of the U.S. Nuclear
Regulatory Commission.
Now, tell me what that's all about. Since when is
a contractor report revised by the NRC? And does that --
MS. BUSH-GODDARD: Would anyone like to help me
with that?
[Laughter.]
DR. HORNBERGER: Well said, Stephanie.
DR. STEINDLER: That's the first time -- I have
read a lot of NRC reports, and that's the first time I've
seen one where the Commission Staff admitted to revising
somebody's report.
DR. WYMER: I don't think you need to answer that.
DR. GARRICK: Howard, are you going to comment to
us about what they're expecting to get from us?
MR. LARSON: Well, Stephanie had -- her questions
that she asked for on concrete, and I guess the other thing
is whether the Committee had any thoughts as to whether or
not the ANVR should be issued, right? But you're planning
on doing it no matter what the Committee thinks.
MS. BUSH-GODDARD: No. In fact, we're taking it
to the Commission for approval to publish it.
And I'm sure that they will also look at what you
all have to say about it. If the Commission approves it to
publish it, then we'll go ahead and publish it.
DR. WYMER: Okay, any other questions?
MR. LEVENSON: I have one. You have suggested
that there are several possible regulatory frameworks in
which this might be issued.
Basically, what's really the difference? What are
the advantages or disadvantages of issuing it, either under
Part 50.82 or, say, maybe another existing regulation?
MS. BUSH-GODDARD: Well, I guess there are pros
and cons of both. Decommissioning of power reactors is kind
of a gray area, because it's -- actually, decommissioning is
under Part 50, which is the utilization and production of
power reactors. But actually you're not utilizing or it's
not producing anything anymore, so it goes into this waste
arena.
Low-level waste is under Part 61, and other
licensee-type Parts. I think material source licenses are
under Part 30 or whatever; I'm not sure. So we're trying to
write a clear regulation. Should it be now in a specific
race arena only, and say, for instance, leave 50.82 alone,
and say if you want -- you know, leave it as it stands, and
say, well, if you want to entomb, you have to go to this
whole entire Part because we realize that it's not a
production or utilization facility.
Or should we leave it under 50.82, because that is
where decommissioning of power reactors, you know, that's
where the regulations are.
So we're struggling with, you know, what, exactly,
is this entombment issue?
MR. LEVENSON: Where, for instance, is SAFESTOR
now?
MS. BUSH-GODDARD: SAFESTOR is not exactly in the
regulations, but the supplementary information to the --
okay, let me start again.
Yes, the supplementary information that talks
about SAFESTOR and DECON are actually located in 50.82. So,
you would go to 50.82 for guidance with SAFESTOR and DECON.
MR. LEVENSON: Do you think there is any advantage
in having it all in one place, rather than having to bounce
around the regulations?
MS. BUSH-GODDARD: I guess that's maybe an
administrative type choice.
MR. LEVENSON: Well, not so much that as that most
of the regulations have all kinds of supplemental stuff, and
if you're moving back from in between regulations, you can
have a lot of changes, whereas if they are all within one
regulation --
DR. GARRICK: I guess one of those options -- and
maybe that's what you were doing, talking about, because I
have been looking at some other stuff while you were talking
-- but one option would certainly be to remove the
decommissioning material from Part 50 and combine it with
the entombment and other things into a separate regulation.
MR. LEVENSON: My gut feeling, without thinking
about it extensively, is that it's all being in one place is
more important than where it is.
DR. GARRICK: Well, yes.
MR. LEVENSON: You have a speaker from NRR that
maybe would like to say something on that.
MR. HOWE: I'm Allen Howe with Industrial and
Medical Nuclear Safety, actually Stephanie's Section Leader.
I just wanted to provide a comment to you. Where we are
right now with the process, we're at the point of developing
a rulemaking plan for this.
Some of these questions that you're asking, we're
also trying to work out ourselves.
We are also in the process of developing an ANPR
and some of these issues, we want to explore as a part of
the ANPR.
In terms of what is the best option, we have not
concluded yet what is the best option for that part of we're
headed in trying to make that determination.
And part of what we're trying to do right now is
to keep you informed as to where we are, what kind of
options we're considering, and in terms of the pros and the
cons of locating the requirements in one part or another, it
certainly is an item of discussion. If we left it located
in Part 50, it would be subject to entombment of reactor
facilities.
If we looked at it for another part, it may be
that the scope is still defined for reactor facilities; it
may be that the scope would be broadened to other things.
But that is the question right now that is in the very
preliminary stages of consideration, and it is something
that will be a part of the information that we provide to
the Commission for their consideration.
MR. LARSON: To one of your questions, Milt, the
Commission did recognize that the Part 50 was written for
the design, construction, maintenance, and operation of
reactors, but they never looked at the back end of the
cycle.
So they did direct the Staff to take a look at the
regulations that might be associated with decommissioning,
and to look at putting those into one section.
I think they are also looking at the GIS.
Now, in regards to the first one, they've said,
well, we'll look at that, and the Staff did make a proposal,
and they said, okay, we'll defer looking at that for awhile
longer.
But the intent is to try and pull the applicable
regulations together, because as you say, right now, they're
here, there, and everywhere, and, you know, even today we're
talking Part 20, Part 50.82, and other facilities.
DR. WYMER: If I understand it, you just said that
you think entombment is enough different or has enough
different aspects to it that you might consider writing a
more broadly based regulation that includes not only
entombment but other things that might be similar but are
not necessarily reactor --
MR. HOWE: Let me just answer that question.
That is certainly an option that could be
considered. The charter that we currently have before us
right now, from the direction of the Commission, and
Stephanie, please assist me with this, is to look at the
entombment option for reactors
DR. WYMER: Okay, so that would rule out what I
just said.
MR. LEVENSON: No.
MR. HOWE: If we want to explore that, that would
have to be something that we would have to go to the
Commission to get their approval with.
MR. LEVENSON: But you have to go to the
Commission anyway.
MR. HOWE: Right. In terms of preliminary
thinking, yes, it has been an item that we have discussed --
what would be the applicability of this type of option to
other applications, other type of facilities.
DR. WYMER: Thanks. Could you hear that over
there, recording this stuff?
DR. GARRICK: Yes, he did.
DR. WYMER: Any other questions? We have run over
Stephanie's time here a little bit.
DR. LARKINS: Ray, I was just curious. What is
the Staff schedule for this ANPR and development of the
options, because a lot sounds very preliminary right now.
MS. BUSH-GODDARD: Well, we have a preliminary
package in office concurrence as we speak.
We are trying to get those comments resolved by
Friday of this week.
DR. LARKINS: When is your preliminary plan to go
to the Commission?
MS. BUSH-GODDARD: February, 2001.
I think ACNW will be on distribution for the
preliminary copies, even before they go to the Commission.
DR. WYMER: When do you need our input?
MS. BUSH-GODDARD: I would like to have it by next
ACNW meeting.
DR. WYMER: That will be in San Antonio.
MS. BUSH-GODDARD: Okay. I will fly there and get
it.
[Laughter.]
MS. BUSH-GODDARD: I don't know your schedule but
I think in talking to Rich Tortel he said that you could
possibly, if you decided to write something up I think
you're going to also send it to the Commission.
I was hoping to have something, you know if
possible, maybe by Thanksgiving in case there were some
comments that I wanted to incorporate into the plan before I
send it to the Commission.
DR. WYMER: You are likely to get a turkey if it
comes that soon.
[Laughter.]
MR. LARSON: Our next meeting is after that.
MS. BUSH-GODDARD: Oh, is it?
MR. LARSON: Our next meeting is that Monday,
Tuesday and Wednesday.
MS. BUSH-GODDARD: Okay -- early December, I
guess, if possible
DR. GARRICK: Well, we will talk about that later
in our reports session. Yes, thank you very much.
MS. BUSH-GODDARD: You're welcome.
DR. GARRICK: Thank you very much. Okay. We are
to what our agenda says is 2 o'clock and we are now going to
hear some reports from members and consultants.
You have the honor of hearing from Bill Hinze
first.
DR. HINZE: Well, prior to Stephanie's terrific
presentation there I was going to use some overheads, but I
have copies --
THE REPORTER: Do you want this as part of the
record?
[Discussion off the record.]
DR. GARRICK: I don't think we do. Who is our
designated Federal official?
All right. For this session he says yes.
[Pause.]
DR. GARRICK: Okay, Bill, tell us what you are up
to.
DR. HINZE: First of all I do want to thank you
for directing me and allowing me to attend these two
technical exchanges. I found them very interesting.
However, I want to say that I think that one of
the momentous affairs of my life occurred this morning, I
heard the first crack in the engineered barrier --
[Laughter.]
DR. HINZE: -- and so --
DR. GARRICK: Geology is back on the map.
DR. HINZE: -- this is a great day for the
geoscientists.
I think it is appropriate that I go immediately
after entombment because --
[Laughter.]
DR. HINZE: -- there seems to be some kind of
relationship there.
Despite the many excellent attributes of the Yucca
Mountain area, there are some negative aspects of the Yucca
Mountain area and certainly those that have the disruptive
events are very much a part of that.
The Yucca Mountain region has been tectonicly and
seismically and volcanically active for many millions of
years and we as geoscientists have nothing to do but to
assume that that is going to continue on for some period of
time.
In fact, within 20 kilometers of the Yucca
Mountain facility, as you well know, we have a 80,000 year
old volcano and we had a 5.6 magnitude earthquake which
occurred in '92 which caused damage, I am not going to say
how much damage, but damage to the FOC, the Field Operations
Center at the NTS. These are examples of the importance of
giving the disruptive events a very sharp look.
Disruptive events are not easy to predict in this
environment, as they might be in some other environments
because in terms of the volcanic activity it is sparse, it
is low-volume. There is little direct evidence and that
also is true of the seismicity, which is widely dispersed,
and generally low magnitude except for the occasional larger
magnitude like the Little Skull Mountain earthquake.
Incidentally, I couldn't help think about, as one
thinks about the Little Skull Mountain earthquake, that
shortly after that earthquake, if you will recall the ACNW
had a walk-through of what was it? -- the Y-Tunnel. I think
that was the name of it, the Y-Tunnel, immediately above the
epicenter of that earthquake, and it had recently been
painted white. The tunnel had recently been painted white
and one of the things that I remember so vividly of that
walkthrough is that we tried to find a chip of white paint
that might have popped off from the wall and despite going
through not with a hand lens but with pretty close scrutiny
we were unable to find any evidence of even something, a
little chip coming off the wall in an epicenter directly
above it, above the epicenter of that earthquake.
Well, in any event, disruptive events are very
important. They are hard to predict and as a result much of
what has been heard at the technical exchanges from the DOE
revolve around the evidence derived from the probabilistic
volcanic hazard analysis and the probabilistic seismic
hazard analysis plus its derivatives.
These basically form the meat and potatoes of the
response of the DOE to the NRC concerns.
In the disruptive events there are these two KTIs
that the NRC Staff has identified, the igneous activity and
the SDS, the Structural Deformation and Seismicity.
I was fortunate enough to attend both of those and
the SDS was just last week. I have prepared a trip report
on each of those and your quiz on those will not be until I
finish, but I hope that you will at least look them over.
I do want to point out though that these are meant
to supplement the NRC/DOE summaries that come out of these
meetings because I really think these go hand-in-glove. I
have made no attempt to do every -- to say everything in the
right words and the correct, exact verbatim of the
agreements between the NRC and the DOE.
On the next page I try to point out the objectives
and the basic results of the technical exchanges.
The NRC has identified in their KTI analyses
several concerns regarding both igneous activity and the
SDS. For example, in igneous activity they have identified
prior to the technical exchanges some 16 different concerns
of various significance, but concerns, and these then were
the subject of discussion in the presentations by DOE where
they have presented additional data and analyses on these
previously unresolved issues leading hopefully to the
closing of these issues.
This requires -- attendance at these requires a
very close attention to what is going on. Things go very
rapidly and particularly if you have not been doing this
every moment of your life.
I was sitting there feeling sorry for myself that
I couldn't daydream at all when I turned and looked at my
neighbor at the last meeting, and it was Jim Curtis, who you
will recall is a lawyer and a former Commissioner, and a
good benefactor of this committee, and he was staying right
with it, right with all of these things, so I figured if a
lawyer could stay with it --
[Laughter.]
DR. HINZE: -- that we could stay with it as well.
Another objective was to develop an action plan
leading to the closure of the KTIs. This has happened to
some extent but it has often led to new concerns.
This is not bringing me another rock, but further
clarification, need for additional data that has been
indicated by the NRC and its coworkers.
The results were these intensive discussions by
the DOE of the NRC concerns and I think that you will be
pleased to know that all issues except one concern in
igneous activity has moved to the closed or closed
pending -- in other words, the NRC feels that they have
enough information or that they see a proper path to obtain
the information.
That one issue relates to the intrusive scenario
in the igneous activity and the number of casks that would
be involved with that and what kind of disruption there
would be to those casks. That is the one remaining issue.
Now in view of the fact that you wouldn't give me
much time to do this discussion, I thought it would be best
if I started with some general conclusions and not only
about the technical aspects of it, but about the process
itself because this is a process that may be new to you.
So on the next page I have some bullets on general
conclusions and the first is that this is an efficient
process. I think this eyeballing, this sitting down and
actually looking at data together or maps together is a very
efficient process which will lead to a much improved,
enhanced site recommendation analysis and license
application, if we reach that point.
The discussions are very open and far-ranging, but
they are very much focused on the technical issues.
Both the DOE and the NRC Staffs are well prepared
and bring a lot of ammunition in the form of backup
expertise with various individuals that have discipline
experience.
The NRC, and here I am speaking about the NRC and
the Center, has done a thorough job of identifying points of
concern in the DOE's AMR, the FEPS, and the TSPA. It is not
immediately obvious that there are any holes in this.
The NRC -- I know one of the things that this
committee has been concerned about and rightly so is is the
NRC overly conservative in their concerns.
That would not be my feeling at all, at least on
the basis of these two. That goes even to igneous, the
probability of an igneous event.
I don't think they have been overly conservative.
The fact of the matter is I think in some cases DOE has
been, if you will, somewhat conservative, and frankly if I
were in their shoes I would probably do the same thing,
because they are covering themselves from the standpoint of
uncertainties in data and inadequate knowledge of some of
the events and so some of their assumptions are overly
conservative and you can talk about that in many ways.
For example, the number of casks that are damaged,
the set-back distance and so forth -- these seems to be
pretty conservative.
There is a general concern that the NRC has about
better documentation and I mention that as a general point
because it is pervasive throughout the entire discussions
and if you look at their summary reports you will see that,
maybe not ad nauseam, but you will see that quite often.
The DOE screens the basis of 63 and this is on the
basis of the individual features, events and processes, the
FEPs, for a 10,000 year period, but one of the questions
that you have to ask, and this was brought up by the NRC at
the technical exchanges, well, what is the impact of these
FEPs in the period immediately following the time of
compliance.
You don't want in 10,001 for something
catastrophic to happen and the fact of the matter is I think
Congress has already stated their concerns about that.
It isn't clear that even though their TSPAs, DOE's
TSPAs are extended beyond 10,000 years that they are
considering the FEPs that may have an effect after 12,000
years. An example of that might global change.
I would suggest that this is something that this
committee or some oversight committee needs to be on the
alert for.
DR. HORNBERGER: Change meanings going to pluvial?
DR. HINZE: A change in the infiltration, a change
in the water table, you know, et cetera.
DR. HORNBERGER: We actually have included that in
there, the TSPA --
DR. GARRICK: Certainly included it in their TSPA
dose calculations.
DR. HINZE: You know, I think you are obviously
right but you want to worry about things that are going to
happen after that 10,000 year period of time after 10,001
and whatever.
The 63 gives them a very definite date on which to
exclude by. One part in 10,000 and 10,000 years, okay? --
and so if something happens after 10,002 it may be of
importance.
It is not clear, and this goes back to your
thoughts, Ray, that DOE is -- it is not clear, as I put it
here, it is not clear that DOE is adequately considering the
effect of coupling the events in the exclusion screening
process -- this one part in 10,000 and 10,000 years.
We also, as I mentioned yesterday, have to be
worried about these events which cross over that may have an
effect upon two different KTIs and get lost in the middle.
There is -- you hear a lot of people saying, well, that will
have to be taken up in engineering design, but somebody has
to make certain that that really is taken up in engineering
design and oftentimes these things are extremely critical.
A couple of other items in general. Staff of the
Center I think have contributed greatly to the NRC's
response to the DOE. I think they have done a great job.
There is also a need to maintain a continuing technical
expertise as these things evolve and we are not through
seeing the igneous activity, even though this committee
might like to say that that is true.
[Laughter.]
DR. HINZE: Well, I put myself in that category
too.
Something that I don't have listed down here but
which is in the summary of my igneous activity trip report,
and I don't know exactly how to say this but the
documentation before -- let me start over again.
I think it is very important that as this
committee feels that stakeholders, public perception, be on
the side of good science and good engineering at Yucca
Mountain and part of that is taking part in these technical
exchanges because you hear a lot and you do a lot.
The problem is that except for the core group in
NRC and the core group in DOE which have had numerous
communications and which have access to all the reports and
all that there is somewhat inadequate documentation both
before and after the meeting for the stakeholder, for the
advisory committees, et cetera, and I think that it would
make life a lot easier.
Let me just give you a case in point and this is
not throwing rocks at anyone but I received through Len's
good graces the PMR and the AMRs the day I was leaving for
the technical exchange. You can understand that these just
then became available. It is essentially impossible to go
into that meeting, sit in that meeting and be a
knowledgeable observer -- all right, I've said enough. I
think you understand.
DR. HORNBERGER: You had enough time subsequently
to digest the AMRs and PMR.
DR. HINZE: Merry Christmas -- and seriously, it
is --
DR. GARRICK: He is our token earth scientist.
DR. HINZE: The fact of the matter is I don't even
have a copy of the PSHA and my PVHA has been pulled apart
and I think to attend these kinds of meetings that it is
extremely important if you are going to get the most out of
them that you have to have this kind of documentation not
only in your hands but under your belt.
John or George, I don't know how much you want me
to go on with these --
DR. GARRICK: I figure we'll be here till 7:30 in
the morning.
Which conclusion are we on?
DR. HINZE: Well, we have gone through the general
conclusions.
Should I just hit a couple of high points? Maybe
I'll try to just hit a couple of high points.
DR. HORNBERGER: Before you do that, you know, I
just am interested in following up on what you just said,
and I take your point that those of us who do this on a very
part-time basis, it is extraordinarily hard to keep even a
tenth of the relevant details in our minds and therefore to
be nearly as well prepared as Staff.
Now I would ask you though -- our hope is that
nevertheless it was worth our while having you go there and
write this report for us because you are technically capable
enough to at least assess some of these general things,
what's going on and whether the process itself is working,
and be able to warn us if there are any red flags that
should be raised.
Are we wrong in assuming this?
DR. HINZE: I think that you get that from my trip
reports.
DR. GARRICK: Right.
DR. HINZE: That is what I carried forward. There
are general observations but there are also specific
observations. I mean we all have our technical expertises
and our special interests and, yes, I think that standing
back may be -- you know, sometimes too much knowledge gets
you into the woods -- and you really need to get back there,
and that is what this committee has always done, I think,
and will continue to do, but it is helpful to be as prepared
as possible and so that's my point.
DR. HORNBERGER: Right.
DR. HINZE: One of the more contentious issues
which has consumed a lot of this committee's time is -- that
is between the DOE and the NRC, is the probability of future
igneous activity.
That contentious nature of that was not really
subdued too much at the technical exchange. It is still
there. It's clearly still there.
The DOE has done the PVHA. They have come up with
basically 10 to the minus 8th per year based upon the ages,
the distribution, and typography of the area.
In contrast to that, as you will remember, the NRC
Staff with the work of the Center have come up with 10 to
the minus 7th to 10 to the minus 8th and they have included
the tectonic controls much more than did the experts in the
expert elicitation.
Frankly, I think the NRC Staff is right on target
here because there is ample evidence that there are some
controls on particularly the more recent volcanic activity
of the tectonism so I think that that has to be given a
great deal of credibility. I mentioned that in the report
and so forth.
I think the key thing is "so what" -- you know,
what is the difference between 10 to the minus 7th and 10 to
the minus 8th. We were very interested to hear that the DOE
indeed has done the TSPA going to 10 to the minus 7th as
well as 10 to the minus 8th. Basically they end up with
about six times greater peak dose for the 10 to the minus
7th over the 10 to the minus 8th, but this peak dose is
really quite minimal.
I think, if my notes are right, for the eruptive
event the peak dose calculation shows .03 millirems per year
and for the intrusive, 1.2 millirems per year and this is
for 10 to the minus 7th.
DR. HORNBERGER: That's within the compliance
period.
DR. HINZE: Yes, surely within the compliance.
DR. HORNBERGER: No, no, I mean that is for the
compliance period.
DR. HINZE: Yes, that's right, excuse me. That is
for the compliance period.
There is some difference here about whether
intrusion, extrusion is important, earlier or later than the
10,000. I don't really think that is a real argumentive
point, a problematic point, but the interesting thing is
here that the DOE says okay, you know, now that they have
run the TSPA as they follow through with their subsequent
TSPAs they will provide 10 to the minus 7th plus their base
case and that's great. That is the kind of cooperation we
want to see.
The other --
DR. HORNBERGER: By the way, Bill, I totally agree
with you and that is when John asked me the question
yesterday about igneous activity. He was, of course,
chuckling, when he asked me the question but my response was
at least partially serious, and that is that I really think
that it is a great example of issue resolution because the
Staff and DOE really came to an accommodation that seems to
me to give satisfaction to both sides.
DR. LARKINS: I am glad to see that you were at
least partially serious.
[Laughter.]
DR. HINZE: We didn't reach agreement on numbers
but we reached agreement on action. That's the beautiful
part about this.
One of the things that enters into this also is
this, is the buried igneous features and this gets into an
old problem of events and the USGS has flown to new aeromags
and I have given you copies or where to get that as an open
file if you are interested in looking at it. I don't
suggest you do because it is kind of arcane but you can't
get the figures off of the website -- at least I was unable
to -- but you can get them from the USGS.
The new survey has really not found any new
events. They found a new magnetic anomaly near Lathrup
Wells. It probably is a lava flow that is associated with
Lathrup Wells.
DR. STEINDLER: You realize the implication of
what Bill said? Regulation by adjudication, you average.
DR. HINZE: That is not the case at all --
[Laughter.]
DR. HINZE: And to establish that --
DR. HORNBERGER: You tried to stuff those words
right into us now.
[Laughter.]
DR. STEINDLER: I have been trying for years.
DR. HINZE: I'd point out that you are --
DR. STEINDLER: Wrong as usual.
DR. HINZE: -- maybe this one time in error.
I will ask you to direct yourself to the -- we are
moving rapidly here -- to the second to the last page under
Structural Deformation and Seismicity KTI agreement, the
faulting.
This was one of the more interesting -- the second
bullet under Faulting.
The second bullet under Faulting is perhaps one of
the more interesting aspects of the technical exchange.
That is that the DOE is using the median of the
hazard as predicted by the probabilistic seismic hazard
analysis. There are further details in the material of the
report plus this and this is the post-closure period.
NRC says wait a second, you know, you should be
using the mean like you are using in the pre-closure period,
and DOE says no, we should be using the median as we do in
the siting of nuclear power plants. That is what I am
getting to -- your average.
This I think remains a very controversial point
and it not only deals with the faulting subissue but it also
deals with the seismicity and the ground motion, not only
with the displacement but the ground motion associated with
the seismic events.
DR. HORNBERGER: When you say it is a big issue,
is it going to matter? Is it going to matter in the bottom
line?
DR. HINZE: We don't know that from the materials
presented.
I did not hear that but the problem, George, is
that there were an expert or two that were way out on the
tail, way out on the tail, and as a result the median falls
beyond the 85th percentile, and so all of a sudden you're
bumping way over here and DOE says what we are doing is just
following the normal routine of the NRC and using the
median.
DR. GARRICK: The mean. The NRC uses a mean.
DR. HINZE: Well, as I understand it in the siting
of nuclear power plants that they use the median and this is
according to Carl Stepp, and I have not looked up the
regulation but Carl, you know, lived with these things
longer than I have.
In any event, as I say here, they have agreed and
I have abbreviated this, the longer expression of this is in
your report, document technical justification for the use of
the median or use of the mean or use of some other
statistical measure that you justify -- but this is one that
we should keep our eyes on very clearly because it may, it
really may have an effect.
Related to this, and I thought this may be of
interest to the committee because of your long-term interest
in expert elicitation, is that -- and it is the first bullet
under Seismicity in this --
DR. GARRICK: Bell, before you get on to that, do
you recall what they said the difference was between the
mean and the median?
DR. HINZE: No, No, and I don't -- it's not that I
don't recall. It's the fact that it wasn't given.
DR. GARRICK: I see, because if they have a median
they certainly have a mean.
DR. HINZE: There is a range of about 10 to the
minus 5th to 10 to the minus 8th for the post-closure
period.
DR. GARRICK: Yes, so if it is highly skewed then
the mean may be anywhere from two to ten times the median.
DR. HINZE: Yes, exactly.
DR. GARRICK: And --
DR. STEINDLER: That's what Bill is saying.
DR. HINZE: That is what I am saying. The median
is way out there.
DR. GARRICK: Of course the other thing that often
means, if that is as a direct result of an elicitation
process, that there's some inconsistencies in the
implementation of the elicitation activity.
DR. HINZE: Once again, you are right on target,
sir. That is the point that I was just bringing up here.
That is, the NRC has asked the DOE to document the feedback
to the subject matter experts following the elicitation of
their respective judgments.
This is to see what kind -- I have gone through
the elicitation process with the Eastern Seismicity and I
know once you give your results then all the calculations
are made and they you are faced with comparing your results
with what everyone else has done and why are you such an
outlier and so the NRC has appropriately asked that they
want feedback on what feedback was given to the subject
matter experts.
Now what DOE claims and I suspect correctly so is
that they followed 1563, the Branch Technical Position.
DR. GARRICK: Right.
DR. HINZE: And recalling from my own days of
going through this with the same group, you know, there was
a pretty fair discussion of that, but nonetheless that is
something to be -- it is the first time we have seen even a
question of a chink in the armor of the PSHA or the PVHA,
and so this would be an interesting one to keep very close
tabs on.
DR. HORNBERGER: I am still curious about your
assessment, because you started out talking about Little
Skull Mountain and looking for white chips of paint, and not
finding any, all right? -- and my question to you as an
expert, post-closure is seismicity a big issue?
DR. HINZE: No.
DR. HORNBERGER: Thank you. I thought I was
missing something.
DR. HINZE: No, but to me I don't think based upon
what I know of the issue that it is going to be a major
problem.
DR. HORNBERGER: Okay.
DR. HINZE: But we have to follow the rules and
standards.
DR. HORNBERGER: No, no, I agree, and I think that
the NRC Staff is absolutely correct for asking for
clarification and what-not, but I am just curious from our
standpoint if we look at risk as the bottom line, yes, we
should keep tabs on this but it is probably not going to be
a big red flag for us.
DR. LARKINS: Just for your information, this is a
reoccurring issue, even in the reactor side. We are looking
at the risk of spent fuel pool accidents, particularly spent
fuel pool fires and those are dominated by the seismic
events.
In trying to reconcile it, the Staff was looking
at the Livermore curves versus EPRI curves, which are about
a factor of 10 difference, and what they ended up doing --
they couldn't reconcile the difference -- was to do the
analysis, the risk assessment using both sets of curves and
in saying where they lay in terms of the safety goal, but
the expert elicitation process, if you are familiar with it,
was slightly skewed in one case versus another case.
DR. HINZE: I think there are some critical
elements going on here in the igneous activity and the SDS
and I think you ought to track them. I think they are
important.
I think the word on the street now is that the
most critical, from the standpoint of dose in the first
10,000 years, is the igneous activity and that is even with
the -- that is both with 10 to the minus 7 and 10 to the
minus 8. I think it is important to follow up.
DR. HORNBERGER: What is your assessment on the
open issue, the open issue having to do with dispersal?
DR. HINZE: That is a good point, George.
The DOE has assumed that the intrusion comes up,
it hits a cask -- a cask, because generally the orifices are
relatively small, a meteor -- and it hits a cask and then
they have arbitrarily selected, and I say arbitrarily
because I didn't hear any evidence -- that three casks on
either side in that drift are destroyed and the lids are
taken off from all of the so-called Zone 2, taken off all of
the rest of the casks.
It is rather -- it looked very arbitrary. There
needs to be a real documentation of the thermal, the nature
of the thermal event, the mechanical and also the shock
effect because if that magma comes up there's going to be a
quite disastrous shock and so we have the mechanical effects
of the magma on the shock wave as well as the thermal.
The other aspect of that is that the NRC, and I
think the NRC is right here again, is that the NRC states
that any intrusion that reaches the drift will also have an
explosion, an eruptive event, violent strombolian, okay?
I think that is very reasonable because that will
come up and the pressure differential will lift that
thousand feet, you know -- it will work its way up.
The DOE, in contrast to that, says no, that they
have these two separate events.
DR. HORNBERGER: Two separate events, right.
DR. HINZE: Right.
DR. HORNBERGER: Actually I thought that the NRC
Staff had agreed on separate analyses for the intrusion and
for the exposure.
DR. HINZE: Yes, they do, but they think they are
going to have both when they have an intrusion event.
DR. HORNBERGER: I see. You know, the only thing
that bothered me in looking at it fairly recently is that
the concern now, and I think it is a concern, is once you
get the ash plume out there, and Staff is now pretty happy
with the way DOE is doing the modeling of the ash plume
because they are basically taking the lead from NRC, but the
real question then is okay, this stuff gets out on the
ground.
Now a big issue is redistribution, post-eruption
redistribution, and we don't know how the hell to do that.
DR. HINZE: You know, this is discussed in the
report, my report, and --
DR. HORNBERGER: I know. I read your report, by
the way, and it was a good report.
DR. HINZE: It really worried me because, you
know, one of the real features of the Amargosa Desert are
the sand dunes.
DR. HORNBERGER: That is correct.
DR. HINZE: And that stuff is going to move, to
say nothing of the working of the soil. That is to enter
into it as well.
DR. HORNBERGER: Whatever happens there.
DR. HINZE: And I really -- the modeling is all
done with this ash plume, which is the Suzuki model, which
is strictly an empirical model.
I would feel much happier about it if we could go
back to first principles, mechanics and thermal, and have a
ash plume model that was based upon first principles rather
than empirical fitting.
It occurred to me that back in another world I
used to be involved in, cratering, in fact out at NTS, and
those days, which was long ago, we were working on models
for cratering and they were pretty primitive --
DR. HORNBERGER: Yes, but you were using modeling
clay, right?
[Laughter.]
DR. HINZE: The fact of the matter, I tested my
models in the sandbox, but that is another story -- out at
Fort Belvoir -- but it occurred to me that there probably
should be some pretty good models out of the cratering
people, and I know from the work that I was involved with
back in those days that we went back to first principles.
I mean we checked it but we really tried to do it
on a first principle basis, and I think that it would be
worthwhile for the -- for someone to look into that.
I think I would have a much better feeling about
it.
You know, along that same line, we can talk a lot
about this, but one of the concerns is the speed of the wind
and the direction of the wind, because currently the DOE is
cutting off their plume at 3.8 kilometers, which is low for
a violent strombolian, which may be conservative but we
should push that to a higher elevation, which means a higher
velocity and if you go to a higher velocity in the Southern
Nevada area you know what happens. You know that from the
radioactive spread from some of the vented nuclear weapon
features. It goes east.
So there is more work to be done in looking at
that whole biosphere issue including the remobilization.
I was really proud of the NRC and its Staff in
looking at these things.
DR. LARKINS: Bill, can I ask you a quick
question?
I notice on here you say "Address NRC concerns
with the assumption that inhalation of 10 to 100 micron
range particles is treated as additional" -- so ingestion --
DR. HINZE: The health physicist -- my
recollection of that, John -- is the health physicist from
the Center brought that issue up and felt that it could lead
to underestimation of the dose, which therefore really has
to be looked at.
There are a number of things in the mass loading,
in this --
DR. LARKINS: I was going to say there's a lot of
information available on the inhalation of aerosols in the
particle size range.
DR. HINZE: My guess is that it would be helpful
if DOE had a better connect with NRC on this and I think
that this agreement really spells that out.
DR. STEINDLER: Did you see any interest in the
chemistry of resuspension?
DR. HINZE: Resuspension?
DR. STEINDLER: Yes -- junk gets down through the
chemistry of transport to the water table, et cetera.
You have a lot of stuff -- lay it down -- then
what? The issue is not entirely due to inhalation.
DR. HINZE: That's right and that is one of the
things that the NRC asked for was there's concern about not
only the inhalation but also drilling down and using the
water that has gone down. Yes. That is part of it.
I think you want me to shut up.
DR. GARRICK: Well, no. This has been very
valuable.
DR. HINZE: But yes?
[Laughter.]
DR. GARRICK: There's a lot of issues with this
that I have struggled with, especially the igneous
probabilities.
The approach of separating the consequence from
the likelihood was very foreign to me as a practitioner of
risk assessment on the basis that the probability is very
much dependent upon the end state and the end state is a
variable and the end state is a consequence.
The justification for that seems to be that if you
get a partial intersection it is about the same as a total
intersection and so the variability that usually exists in
catastrophic events doesn't exist in this one, so that has
been the simple explanation.
DR. HINZE: Good point.
DR. GARRICK: And also the issue you bring up
about the median and the mean, that is a traditional one. I
thought it had been resolved.
If you really believe in uncertainty and you want
the central tendency parameter that best represents
uncertainty it has to be the mean, and so I am surprised
that there is a debate over that.
DR. STEINDLER: Well, isn't there always the
question of skewed distribution?
DR. GARRICK: When you calculate a mean, you
utilize the -- you calculate an expected value and that
expected value calculation embraces all of the
probabilities.
DR. STEINDLER: But for a skewed distribution --
DR. GARRICK: Well, yes -- but if the skewed
distribution is in fact as a result of a consistent
interpretation of the evidence.
DR. STEINDLER: Yes. That is the issue, precisely
the issue.
DR. GARRICK: And if it is not -- and that's where
I don't think it is, and so I would agree with you if
there's some high level of suspect on the distribution, but
that is not something we are going to --
DR. HINZE: One of the real problems there is that
the DOE is using the mean in the preclosure and the median
in the postclosure. You know, that smells like a day-old
fish.
I mean certainly the NRC's requests here --
DR. HORNBERGER: If they are doing it. If that's
correct then I would argue that at least they are doing it
the right way, because the mean will be conservative and
preclosure is when seismicity probably is important and you
probably want to be conservative and postclosure is probably
who cares.
DR. HINZE: Achh -- you can buy me a drink.
[Laughter.]
DR. GARRICK: That's very good, Bill, and very
helpful and your reports are comprehensive and enjoyable to
read. Okay.
Let's see -- Ray, do you want to make a few brief
comments about the decommissioning conference?
DR. WYMER: I can be very brief.
DR. HINZE: Excuse me. There was a good old guy
and he made copies of the attachments for this last report
on the SDS.
DR. GARRICK: Oh, good.
DR. HINZE: So these are for you. They are the
attachments and your quiz will be --
DR. GARRICK: Oh, my --
DR. HINZE: Seriously, there's a lot of
boilerplate in there but there's a lot of goodies too and
flick through them, okay?
MR. LARSON: You are getting even with us for the
PMRs.
[Laughter.]
DR. HINZE: Yes.
DR. GARRICK: Okay, Ray, and then we will take an
overdue break again.
[Whereupon, at 3:25 p.m., the recorded portion of
the meeting was recessed, to reconvene at 8:30 a.m.,
Thursday, October 19, 2000.]
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