ACNW Audit Review of Chemistry Issues for the Yucca Mountain Site Considerations Report

                Official Transcript of Proceedings


Title:                    ACNW Audit Review of Chemistry Issues for
                               the Yucca Mountain Site Recommendation
                               Considerations Report

Docket Number:  (not applicable)

Location:                 Rockville, Maryland

Date:                     Thursday, February 22, 2001

Work Order No.: NRC-078                                Pages 1-38

                   NEAL R. GROSS AND CO., INC.
                 Court Reporters and Transcribers
                  1323 Rhode Island Avenue, N.W.
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                                 + + + + +
                           CONSIDERATIONS REPORT
                                 + + + + +
                             FEBRUARY 22, 2001
                                 + + + + +
                            ROCKVILLE, MARYLAND
                                 + + + + +
                       The ACNW Audit Review Committee met at the
           Nuclear Regulatory Commission, Two White Flint North,
           Room T2B1, 11545 Rockville Pike, at 8:30 a.m.,
           Dr. Martin Steindler, Acting Chairman, presiding.
                 DR. MARTIN STEINDLER, Acting Chairman
                 DR. JAMES CLARKE, Member
                 DR. PAUL SHEWMON, Member

           .           ACRS STAFF PRESENT:
                 DR. ANDREW C. CAMPBELL
                 DR. TAE AHN
                 DR. JOHN BRADBURY
                 DR. RICHARD CODELL
                 DR. BILL DAM
                 DR. CARL DIBELLA, NWTRB
                 DR. DAVID ESCHE
                 DR. BRET LESLIE
                 DR. TIM MCCARTIN

           .                                A-G-E-N-D-A
                     AGENDA ITEM                           PAGE
           Recap and Discussion of Issues . . . . . . . . . . 5
           Presentation by David Esche. . . . . . . . . . . . 8
           Adjournment. . . . . . . . . . . . . . . . . . . .38

           .                           P-R-O-C-E-E-D-I-N-G-S
                                                    (8:30 a.m.)
                       DR. CAMPBELL:  All right.  The situation
           is that Dr. Steindler here is going to be the Chair
           for this morning's session, such as it is.  All of the
           group has gotten early flights out to avoid getting
           caught in the storm that is eminent.
                       And Ray actually had to catch a flight
           very early.  So he had already had to go.  Otherwise,
           he was going to get stuck here.  So, Dr. Steindler
           will chair the meeting, and what we are going to do is
           we are going to have to adjourn before 10 o'clock, is
           that right, Gentlemen?
                       ACTING CHAIRMAN STEINDLER:  Yes, I believe
                       DR. CAMPBELL:  And we are going to go
           ahead and have Dave Esche from the NRC staff discuss
           some of the aspects of the TPA code.  We will be
           adjourning about 10 o'clock this morning because of
           the situation with the snow coming and people having
           to catch flights.  So with that, Marty, the floor is
                       ACTING CHAIRMAN STEINDLER:  Thank you very
           much.  Unaccustomed as I am to public speaking, if I
           can find my agenda, I would be in good shape.  There
           will be no introductory remarks by Ray Wymer.
                       And there will be a little bit of a
           discussion as to what we learned yesterday, or what
           transpired yesterday.  The focus of the meeting was or
           is chemistry, and specifically chemistry as it relates
           to the waste package, and its role as a source term
           for using and transport.
                       We did hear some of the issues, but
           certainly not all of them, dealing with the chemical
           background built into the models.  We heard
           considerable discussion on corrosion and were told in
           no uncertain terms that the excessive use of
           conservative assumptions could easily lead to a
           nonsense output.
                       However, we do I think have to change the
           role of our normal protocols, and this is not a
           scientific discussion.  This is a practical analysis
           of what needs to be done to satisfy the Commission
           through the staff, and provide them with reasonable
           assurance that the models that DOE is using that are
           checked by the staff are appropriate for in our case
           ultimately the license application.
                       I think that is the focus, and our focus
           is to determine whether or not the staff, the NRC
           staff, is able to satisfy that role and specifically
           how are they doing it.
                       We heard a considerable amount of
           information and handed a considerable amount of
           information on the methodology, the process that the
           staff is using to resolve what they call issues, which
           are really questions to the Department of Energy on
           the source, the nature, and the implications of some
           of the assumptions and activities in the models and
           their abstractions.
                       It isn't very clear at this point whether
           the staff believes that they are in satisfactory
           condition, considering that they don't have a whole
           lot more time between now and the time that, one,
           somebody is going to ask them about the TSPA site
                       And not a whole lot of time when the TSPA
           licensing application is going to come bouncing on
           somebody's desk.  With that, I would suggest that one
           of the important issues that we are going to try and
           at least address today is whether or not the staff can
           produce estimates on an independent basis of the
           behavior of the Yucca Mountain system as it is
           described in gross terms by the Department, but as it
           is described in detail models by the staff themselves.
                       The issue will be, one, is that doable,
           and has that been done, and two, and perhaps most
           important, how independent is that exercise done by
           the staff.  It is at the moment to us here, but
           obviously not to other people, somewhat immaterial
           what the answers are, unless the answers get to be
           drastically different than what the corresponding
           Department of Energy results are.
                       And then somebody needs to at least look
           at the reasons for that difference, and try to unravel
           those.  With that, my suggestion is let's hear what we
           can about the staff's efforts to model abstract and
           calculate.  Can we do that?
                       DR. ESCHE:  Yes.
                       ACTING CHAIRMAN STEINDLER:  All right.
           State your name, rank, and serial number, and sit
                       DR. MCCARTIN:  Can I just add one thought?
           You talk about the differences, and I think whatever
           calculation the staff does, we will have to know why
           we got our numbers, and why DOE got their numbers, and
           whatever comparisons are appropriate.
                       And I will give you the best example I
           have.  To date, generally our calculations show
           similar doses and similar release rates.  DOE has a
           much higher release rate, but takes a very large
           credit for cladding.
                       We take no credit for cladding and have a
           lower release rate.  We get a similar answer, but for
           drastically different assumptions, and I think that is
           the healthy part of the process, is that we will
           understand not only our own results, but DOE's.
                       And whatever assumptions affects ours,
           versus theirs, I think -- and whether we have to walk
           through them all in the licensing area is another
           issue, but I think we have to understand all those.
           And we get the same results, but like I said, for very
           different reasons.
                       ACTING CHAIRMAN STEINDLER:  That's quite
           right.  It isn't just focused on the number at the
                       DR. ESCHE:  All right.  I am Dave Esche,
           and I am in the Performance Assessment Section, and I
           am in charge of the TPA5.0 code development.  I was in
           charge of the TPA4.0 code development, because Tim was
           responsible for that in the past, but he got
           overwhelmed with rule makings.  So the activity was
           shifted to me.
                       One of the things that we are looking at
           for TPA5.0, and working pretty hard on developing, is
           a revision to the gas and seepage models.  And I think
           this picture up on the screen is a pretty good
           representation of the methodology to use to try to
           evaluate that chemistry.
                       It is the connections and flow paths that
           the DOE is using, and I think it is a pretty good
           picture of how things will be moving, and in what
           locations you may need to evaluate the conditions.
                       And our focus right now is on location one
           and location two for the time being.  What is the gas
           and seepage chemistry coming in, and then what happens
           to that once it gets on these engineered systems.
                       So we have a team made up of Gustavo, and
           Tae Ahn, and the CLST folks, the corrosion people,
           working with the near-field environment people, and
           the TEF, thermal effects on flow people, and all of
           those are put together to try and evaluate this
                       The hard thing is that you have
           uncertainties coming in each area, and so what does
           that mean.  What we are trying to define is what is
           the window of environmental conditions that we think
           you may have there.
                       The answer may be that the engineered
           system is still robust after you have defined that
           window, but for right now that window is pretty ill-
           defined, and so we are working to better define what
           that window is.
                       And at location two, we have a group at
           the Center that is using a code called OLE, I believe,
           which is -- well, it is to predict the concentrations
           of salts under very extreme conditions.
                       So EQ36 breaks down at a certain ionic
           strength, and it is no longer applicable, but this OLE
           code, I guess, is used or has been used at Hanford to
           evaluate what is the chemistry of these extreme
           conditions, and that's what we are trying to use at
           location two to evaluate what happens to the
                       So our idea is that we are going to
           propagate the differences in the chemistry and water
           coming in from location one, and if we have high
           temperatures, and a hot repository, then that water
           coming in boils and leaves something there.
                       So we try to evaluate what is there, and
           then based on what is there, then that determines what
           happens to the chemistry from that point.  There is
           some key uncertainties, like what happens when you go
           from completely dry to you first start wetting.
                       What is the chemistry that that surface is
           seeing, and is it aggressive to those metallic
           materials.  Well, it is hopeful that the corrosion
           people can get data.
                       Once we define what the window is, then
           maybe they will be able to do some tests and evaluate
           it to see if there are any corrosion problems in that
           window o susceptibility.
                       ACTING CHAIRMAN STEINDLER:  When you say
           wetting, you mean gross wetting?
                       DR. ESCHE:  Well, we have both.  Like we
           have considered that some locations may have seepage,
           but other locations may just have an increase in
           relative humidity.
                       So the relative humidity may be low where
           it is effectively dry, but then the relative humidity
           increases, and depending on the compositions of the
           salts that are there on the surface, that will define
           when you start having moisture present on that
           surface, and at what temperature effectively.
                       But the key problem is propagating the
           uncertainties, because you have so many permutations
           that you can only do a subset of those permutations,
           and how do you choose what the right subset is.
                       So we are doing the best we can in trying
           to calculate the edges of that window, but we are not
           going to be able to do every point within that window
           of different chemistries.
                       But in performance assessment -- and I
           have heard you guys talk about this, but we always
           want our most realistic number, and then our range of
           uncertainty.  We don't like the conservative bounding
           effects, because when you propagate it through 10, or
           15, or 20 perimeter distributions, you start ending up
           with a ridiculous result, which has been said.
                       So we try our best at, okay, this is what
           we expect to happen, and this is our uncertainty,
           rather than setting things towards the ends of
                       Lauren Browning would be good to talk
           about this, but she is on an audit out at Las Vegas.
           She is the one who is coordinating the work down at
           the Center.
                       And it is likely that for TPA5.0 that we
           will have at least some revision to the chemistry
           model, but we might not get the whole way to where we
           want to be, because it is resource consuming, and it
           requires cooperation between five different
           disciplines basically.  It is a difficult problem, a
           really difficult problem.
                       But I think this picture that is put on
           the board is a pretty good framework.  You run into
           all sorts of complexities though, like what happens
           when you go from dry to wet, and you don't really have
                       What happens if the salt on the surface
           has some porosity to it that causes vapor pressure
           lowering, or if you form an aggressive condition on
           the top of the drip shield, and the drip shield fails,
           what is the mass transfer of that material then to the
           waste package surface.
                       And if you don't have dripping is there
           any mass transfer, and if you have intermittent
           dripping, and so we are going to try and model it with
           basically equilibrium calculations at each step or at
           each point in time.
                       And maybe that is a bad assumption, but
           considering that we probably won't have much data
           about the kinetics of some of these mineral phased
           dissolutions, et cetera, that is probably the best
           that we can do to get a rough answer at what is
                       DR. SHEWMON:  You sort of dropped your
           voice as if you are finished.  Are you going to get to
           location three, or is that somebody else?
                       DR. ESCHE:  Well, as to location three,
           what we imagine is that when we have an intact drip
           shield, we will evaluate the chemistry at location
                       And then if we open a gap in the drip
           shield due to either general corrosion, et cetera, we
           will propagate the environment at location two with
           some mast transfer mechanism to location three.  When
           the drip shield is intact, we don't imagine that we
           will have progressive chemistries at location three.
                       DOE has collected information on dust, and
           it is going to evaluate what the chemical composition
           of that dust is.  So maybe the dust interacting with
           relative humidity gives you some sort of environment
           at location three.
                       But it certainly is not going to be as
           aggressive as the test conditions that we have seen so
           far.  So maybe it is of minor concern.  And maybe that
           is --
                       ACTING CHAIRMAN STEINDLER:  It looks like
           your temperature is going to be higher.
                       DR. ESCHE:  Yes, your temperature will be
           higher.  So at location three, it is conditional on
           what happens to that barrier above it.  We won't have
           an aggressive chemistry at location three until we
           have a hole at location two.
                       Or if our mechanical folks said that you
           can form gaps in the drip shield due to seismicity,
           then that would provide the opportunity for the
           environment, either the seepage water from  location
           one going directly to location three, or seepage water
           that lands on location two.
                       DR. SHEWMON:  And currently the seismicity
           people have decided that the seismic won't break up
           the drip shield.  Isn't that what I read someplace?
                       DR. ESCHE:  Yes, DOE has calculated both
           that it won't fail the drip shield and that it won't
           open gaps in the drip shield, because they designed
           the drip shield with, I think, a lip on each side that
           kind of locks over the top of it.
                       So the seismic forces just aren't large
           enough to pop those off and make a space.  But I don't
           know what we have done what the NRC feels or the
           Center feels about those calculations, but that is
           DOE's results.
                       ACTING CHAIRMAN STEINDLER:  Okay.  Other
           than the attention to conservative estimates, how does
           this differ from the TSPA?
                       DR. ESCHE:  How does it differ from DOE's
                       ACTING CHAIRMAN STEINDLER:  Yes, DOE's
                       DR. ESCHE:  I think they aren't using --
           they aren't evaluating -- they are modeling what
           happens to the chemical conditions at location two
           when you go from completely dry to start wetting.
                       So we are trying to better get a handle on
           what is happening in that time regime, and what is
           happening to the chemical condition at location two
           when you go from dry to wet.
                       If you look at the ionic strengths that
           they have in their model, the ionic strengths that
           happened at location two are much lower than what
           happens when you have a salt or precipitate layer on
           the top of the drip shield, and you start adding a
           little bit of water.
                       So the ionic strengths are much lower than
           that.  I don't know exactly what the assumptions were
           in that regime, but I think we are evaluating location
           two differently, and with a different code, and with
           a different -- well, maybe the same geometric
           framework, but maybe a little bit better consideration
           of the time scale to the processes.
                       And whether that is -- and I don't know
           about the process model, but in DOE's TSPA they used
           500 year time steps.  Well, if you use the 500 year
           time step and you were trying to look at chemistry
           that is happening at location two, you skip right over
           all those processes that happen when you go from dry
           to wet.
                       How important are those?  Well, maybe they
           are not important at all, and maybe some simple
           testing could identify that, and I think that it is
           testing that DOE is doing.
                       They have samples that are halfway
           submerged, and sickled wet-dry, and we can model it to
           death, but the data is really the good way to put to
           rest some of these things.
                       ACTING CHAIRMAN STEINDLER:  Why did you
           think that was an important thing to do?
                       DR. ESCHE:  To look at the wet-dry
                       ACTING CHAIRMAN STEINDLER:  Yes.
                       DR. ESCHE:  Just because the -- well,
           whether you have, say, a localized corrosion
           phenomena, for our model, it is dependent on the
           temperature and the ionic strength.  You need high
           temperatures and high ionic strength.
                       So what is happening when you go from dry
           to wet is that you should have the maximum -- at that
           point in time, it should be the maximum of both ionic
           strength and temperature.
                       So if you have certain deliquescent
           mineral phases on that surface, they will start taking
           water from the atmosphere before, say, if you had
           sodium chloride there.
                       So depending on the mineral phases that
           you form will define the temperature and ionic
           strength that you have.  And it might be a short
           period of time, and maybe it is not important, but if
           the corrosion rates are fast, that period of time may
           be important to try to characterize, and so that is
           what we are working towards.
                       ACTING CHAIRMAN STEINDLER:  It still isn't
           clear to me whether or not in the grand scheme of
           things if it is worth the effort if it looks like what
           is going to take to get a better handle on what is
           going on.
                       DR. ESCHE:  I think in the grand scheme of
           things that it may not change the result at all, but
           at least that we asked and answered the question would
           provide confidence that the -- well, right now a lot
           of people have uncertainty, yourselves or the NWTRB,
           that you have this package that lasts 50,000 years or
           a hundred-thousand years, a million years.
                       And actually at a hundred-thousand years,
           only .2 percent of the surface area has failed.  So
           you have a few hole, but generally the thing is pretty
                       ACTING CHAIRMAN STEINDLER:  The surface
           area of what?
                       DR. ESCHE:  The surface area of the waste
           package.  Only .2 percent has actually failed at a
           hundred-thousand years.
                       ACTING CHAIRMAN STEINDLER:  So that is
           what I am getting at.  If in fact that is true, I
           guess I can argue that the amount of resources that
           you are going to spend, and the folks that you are
           going to try and pull into this team that you have
           got, may not be worth the effort.
                       DR. ESCHE:  Well, certainly --
                       ACTING CHAIRMAN STEINDLER:  In other
           words, how did you pick it?
                       DR. ESCHE:  How did we pick what?
                       ACTING CHAIRMAN STEINDLER:  Why did you
           pick that?
                       DR. ESCHE:  Because the waste package is
           the most risk significant thing in the whole system.
           If the waste package isn't working, then that is the
           only way you start getting close to doses that would
           violate the standard in the regulatory time period.
                       ACTING CHAIRMAN STEINDLER:  So you must
           have had some assumption that the approach that DOE is
           using is unsatisfactory or uncertain.
                       DR. ESCHE:  Well, it is uncertain, yes.
           Unsatisfactory, I would say no.  They have made leaps
           and bounds in that area, and they continue to work
           further.  But in a lot of these areas, we find -- we
           don't know the right questions to ask until we look at
           the problem ourselves.
                       And when we look at the problem ourselves,
           then we say, oh, we should have been asking about
           this.  So that's why we do a lot of the independent
           analysis that we do, because when you are reading a
           document and you look at it, and you go through it,
           and you may find questions.
                       But when you try to solve the problem
           yourself, you identify a lot of different things than
           when you identify it by just looking at a document.
                       So that's  what I see the utility of it
           is, and the engineered barrier system is the most risk
           significant system.  And even if you take out the
           engineered barrier system though, the natural system
           still does the time.
                       You can see just by some of the
           neutralization analyses that DOE Did that a lot of
           these things are working in combination to take that
           hazard down.  So it is not just the engineered system,
           but in the regulatory time period, or in the 10,000
           year time period, the engineered system is buying you
                       DR. MCCARTIN:  If I could add one point.
           I think the regulatory question that we have been
           pushing DOE on -- and I will say maybe about a year-
           and-a-half ago that we raised the question, and they
           said we will have no waste package failures in 10,000
                       They have made that statement, and we can
           defend it, which is fine.  The question we asked is
           have you considered an appropriate range of conditions
           that would affect the waste package in a deleterious
           way, and they said we believe we have.
                       And that is where the staff is now, okay,
           are we certain, and we are just pushing to make
           certain they consider an appropriate range of
           conditions for that 10,000 life time.
                       And then not too long afterwards, you guys
           are aware of the State coming in with the trace
           metals.  And I think it is just the ZLST people at the
           center and NRC, and the near-field people, let's get
           together and make sure how we found the conditions
           that we think would capture an appropriate range for
           defending that 10,000 year lifetime.
                       ACTING CHAIRMAN STEINDLER:  Okay.
                       DR. CAMPBELL:  Just for the record, that
           was Tim McCartin from the NRC staff, and Dave Esche is
           the speaker at the table of the NRC staff.
                       Given, Dave, what you said about the 0.2
           percent failure at a hundred-thousand years, and the
           doses associated with that, I think that emphasizes
           the importance of establishing with some high degree
           of certainty that in terms of reasonable assurance
           that  the 10,000 plus lifetime for the waste packages
           is defendable in a hearing type of process.
                       And not only on every technical aspect of
           it, because 0.2 percent is a pretty small segment of
           -- I mean, there are a lot of waste packages in there,
           and that is still a lot of surface area.  But when you
           start thinking about failure rates of normal stuff
           that people have in their every day lives, you are
           looking at 5 percent being an acceptable failure rate.
                       ACTING CHAIRMAN STEINDLER:  Are you
           talking about washing machines?
                       DR. CAMPBELL:  Right.
                       DR. CAMPBELL:  But you see what I am
           saying, is that is what most people are dealing with
           in their normal lives; is that 5 percent of the
           products that I get are a lemon, and they are worried
           about that.
                       And then you say, okay, now 2/10s of a
           percent at a hundred-thousand years, and we are
           getting doses that far exceed the limit, even though
           we are way out in time, a lot of people are gong to
           say, hey, it doesn't take much failure earlier on to
           get you into trouble in terms of compliance.
                       DR. ESCHE:  That was -- the .2 percent is
           surface area failed, and the actual percent failed,
           the ones that get very small holes, or cracks, I think
           it is like 50 percent have cracks in them, and 26
           percent have patches.  But it is only .2 percent of
           the area.
                       DR. CAMPBELL:  Right.
                       DR. ESCHE:  It is kind of number smithing
           or something, but in general the amount of surface
           area failed is very small at a hundred-thousand years.
                       DR. SHEWMON:  Failure here is significant
           corrosion or penetration?
                       DR. ESCHE:  Well, the larger numbers are
                       DR. SHEWMON:  No, the .2 you said was --
                       DR. ESCHE:  The .2 is a 6-inch-by-6-inch
           patch, I think, is roughly the size if a hole failed
           that big.
                       DR. SHEWMON:  So that is penetration.
                       DR. ESCHE:  So it is an opening, yes.
                       DR. SHEWMON:  Thank you.
                       DR. CAMPBELL:  But isn't that an
           assumption of the size of that?  It assumes --
                       DR. ESCHE:  It is just the size selected
           to model the problem.
                       DR. CAMPBELL:  Based on general corrosion
                       DR. ESCHE:  Yes.
                       DR. MCCARTIN:  But DOE gets releases from
           cracks, no matter how small, or early, or how much
                       DR. ESCHE:  And the other thing you have
           to remember is that if they have a patch that fails
           and let's say a 6-inch-by-6-inch patch, they have
           diffusive releases over that whole area.  So that
           whole 36 square inches or whatever.
                       In reality, you are going  to have a water
           film around the outside of that hole, which is the
           diffusive area.  So they might be greatly
           overestimating diffusive releases which are making
           those numbers a hundred-thousand years much larger
           than they may be in reality.
                       So some of those conservatisms you have to
           keep in mind when you are looking at what the curves
           are telling you at the later times, and I think they
           are working on evaluating that, and you may see a
           revision to that in the future.
                       DR. CODELL:  Dick Codell, NRC.  And in
           fact almost across the board the DOE puts this
           diffusion model in, and it seems wherever they have
           that that they have exaggerated it.
                       For example, they assume that the waste
           package is sitting directly on the inverts, and so
           there would be a direct pathway, and without taking
           any credit for the fact that it is sitting on a metal
           stand right above the invert.
                       And that like the example that I gave
           yesterday where the waste package just failed and that
           it would lead to the maximum diffusion.  I mean, it is
           not our job to tell them to be less conservative, but
           it just struck us all that way.  That the diffusion
           models in their TSPA are exaggerated.
                       DR. ESCHE:  I guess the only thing we were
           worried about was the conservatism, as if it is
           masking what we should be worrying about.  So like
           maybe the amount of advective flow is really what we
           should be concerned about, and the uncertainties
           associated with that.
                       But if we have a conservative diffusive
           model clouding that, then we might not be focusing as
           much attention on what are the uncertainties in the
           seepage model, you know.
                       So that's where we -- at least in PA
           space, we try to communicate what we think and that
           you may need to look at your conservatism here.
                       I mean, when uncertainties are large, in
           some instances you have to be conservative.  But you
           have to be careful in risk assessment that you are not
           doing that all over the place, and that you aren't
           generating some goofy number, I guess.
                       DR. CAMPBELL:  Well, we did talk about
           this issue of what appeared to be -- and I will use
           the phrase "ultraconservatism" in the way that they
           are implementing diffusion in their models.
                       And not only setting a boundary condition
           at zero concentration, and never altering that, even
           though obviously if a species is diffusing along that
           gradient, then the gradient is going to be attenuated
           with time.
                       DR. ESCHE:  Sure.
                       DR. CAMPBELL:  Otherwise, things would
           diffuse away from everything, and we would all be in
           some sort of equilibrium state that doesn't exist in
           the real world.
                       But that even raises even more questions
           about the value of these neutralization analyses,
           because the way that they implement neutralization of
           the waste package is to impose a 300 centimeter square
           patch open.
                       And if you are saying that then have 300
           square centimeters of diffusion in an area, and you
           multiple that by the 8,000 or so waste packages in
           there, you can see where these high doses come out on
           the calculation.
                       But it has no relationship to a real world
           type of situation of failure, and that creates a lot
           of issues, I think.  That maybe it isn't the place of
           the NRC to comment about the conservatism built into
           that, but it sure can mask a lot of other -- you know,
           as you say, potentially important issues, because that
           just dominates all the release.
                       DR. MCCARTIN:  And you don't need water.
           You assume there are monolayers of water all the time
           and that's the fusional --
                       DR. CAMPBELL:  Right.  Well, you need
           water, but all you need is a few monolayers of it.
                       DR. MCCARTIN:  Well, they make no
           calculation with respect to water, in terms of how
           much is there, et cetera, especially for the
           neutralization that it has failed at T zero.  That is
           pretty hot.
                       And in terms of perimeters, for the
           diffusion coefficient for source term in the waste
           package is 10 orders of magnitude larger than the
           diffusion coefficient they use in the unsaturated
           zone; 10 orders of magnitude larger.
                       DR. CAMPBELL:  Are they using pure water
                       DR. MCCARTIN:  Oh, yes, for the source.
           But in the unsaturated zone and the matrix diffusion,
           they have a number that is 10 orders of magnitude
           less.  And that's fine, as it certainly can't be any
                       DR. CAMPBELL:  No, it's not fine.
                       DR. MCCARTIN:  Well, it is their
           calculation, and they need to put forward what they
           think they can defend and support.  And as long as we
           know what they are doing, we can evaluate.  And it is
           not our calculation.
                       DR. ESCHE:  Usually when you are doing
           something conservative, there was a reason for it.
           But in some instances maybe it is a little too far,
           you know.
                       DR. CAMPBELL:  Well, I guess what disturbs
           me is that diffusional ungradience is not a new
           phenomena, and it is 19th Century science.  This is
           not a new phenomena, and for DOE to take the position
           that this stuff is too uncertain to deal with in a
           more realistic fashion I find incredible.
                       DR. MCCARTIN:  Sure.  And the only thing
           -- and Dick may remember this better than I -- and Tae
           -- but there are some experiments where DOE has some
           information that the experiments were flawed, but I
           thought they suspended the spent fuel particle, and
           they got some concentration above a pool of water, and
           they got some concentrations in the water.
                       And you back out some numbers, and we have
           measured this, and we can't say that something isn't
           going on here.  And this is about 4 or 5 years ago.
                       DR. CODELL:  Those were the experiments at
           Oregon on spent fuel.
                       DR. MCCARTIN:  And Dave is absolutely
           right.  We look at this and we want to understand this
           assumption of what it does to the calculation, because
           it can cloud some of your results.
                       But DOE has an experiment or two out there
           that tends to support some larger releases, and it
           could be their concern with that experimental evidence
           that we will not be able to refute it.
                       DR. CAMPBELL:  Is this documented in an
           AMR somewhere?
                       DR. AHN:  Well, originally in the early
           '80s, Northwest Laboratory, supported by DOE, spent a
           long time on spent fuel testing.  In other words, in
           emerged air or simulated ground water, and
           periodically measured the dissolution rate over a long
           period of time, from 5 to 7 years.
                       Then all of a sudden a new testing was
           initiated in Livermore, and they attempted to study a
           fundamental using only a single carbonated solution,
           excluding all complicated species.  The test method
           was different and it was a so-called flaw testing to
           determine the dissolution rate.
                       That rate was very, very high compared
           with the emerging test results, which came from real
           well water conditions.  We hoped that they could
           incorporate that in other species later on, but they
           never did it.
                       They kept going on with the single
           carbonate solution, because they wanted to understand
           the very basic mechanism.  Later on we questioned them
           on why do you need to do that, and they said, well,
           this testing is conservative.  That was the only
                       ACTING CHAIRMAN STEINDLER:  Okay.
                       DR. CRAGNOLINO:  Well, I know that it is
           important about what Dave Esche mentioned and
           understanding the chemistry and the drip shield, and
           the waste package and the corrosion, and that the drip
           shield was conceived by the DOE as a way to control
           the flow of water, and this was a very strong
           statement in number two.
                       And from the point of the engineered
           barrier system, the two principal factors were the
           performance of the waste package and the performance
           of the drip shield.  However, if you look in the
           recent recital, and condition three, it is not the
           drip shield alone.
                       Now it is the drip shield drift invert
           system.  Why?  Because apparently the drip shield has
           not played the significant role that was expected by
           using the dose after 60,000 years.  And I think this
           is an important modification, and is something that we
           have to explore in more detail.
                       It changed the emphasis, and the emphasis
           is now more in the relief and leaving aside
           performance of the waste package.  This is where we
           really have to refine our approach to the knowledge in
           the same way that David has mentioned.
                       DR. ESCHE:  Well, the way I look at the
           drip shield is that it may not show up in the current
           analyses as being extremely important because of the
           large diffusional releases, and it is mainly
           preventing water flow.
                       But it also minimizes rock fall and
           aggressive chemistries if you have it.  So like say
           the titanium is only susceptible to fluoride, for
                       Well, the time that the drip shield lasts,
           which is on the order of 10,000 years in our model,
           and 20 to 40,000 years in DOE's model, I think, you
           would expect that most of that aggressive chemistry
           has been rinsed out of the system so to speak by the
           time of the drip shield failure.
                       ACTING CHAIRMAN STEINDLER:  Why would you
           expect that?
                       DR. ESCHE:  Well, in DOE's model, what
           happens is when you have seepage, it is just as a
           mixing cell.  So the seepage comes in and mixes with
           the salt and carries some of it out, and that is
           enough to dilute the chemistry back to ambient pretty
                       ACTING CHAIRMAN STEINDLER:  But ambient
           fluoride, which is the issue.
                       DR. ESCHE:  Well, the ambient fluoride, I
           think we heard, was 4 milligrams per liter.  And from
           what our people told me, the corrosion of the drip
           shield requires a threshold fluoride concentration,
           but the fluoride is consumed in the reaction.
                       So you need to get a higher fluoride
           concentration, but then you need a certain mass flow
           of fluoride into the system for the corrosion, because
           it is consumed in the reaction.
                       But if the drip shield is preventing all
           these chloride and other salts that are formed there
           initially, those salts are probably rinsed out either
           due to seepage water in, or relative humidity becoming
           high again.
                       And by the time the drip shield fails the
           aggressive chemistry is prevented on the waste
           package.  So we forget that whenever we are doing the
           analysis, too, because right now the data suggests
           that even if you have those aggressive chemistries,
           the waste package only in DOE's model has general
           corrosion and stress corrosion cracking.
                       Localized corrosion never happens for any
           of the conditions that are generated, and so that is
           the issue.  If you have a different window and those
           conditions were generated, would you have localized
           corrosion, and that's what we are trying to find out.
                       And it would build credence to, oh, yeah,
           the drip shield doesn't show up in your model as doing
           much now, but there is maybe a good reason for why it
           is there.
                       ACTING CHAIRMAN STEINDLER:  Okay.  Any
           other comments or questions?
                       DR. MCCARTIN:  One quick correction.  It
           is not a 10 order of magnitude.  It is only a 2 order
           of magnitude.  I did the unit conversion in my head
                       ACTING CHAIRMAN STEINDLER:  So two orders
           of magnitude.
                       DR. MCCARTIN:  Two orders of magnitude.
                       ACTING CHAIRMAN STEINDLER:  That's still
           not bad.
                       DR. ESCHE:  And my comments about what DOE
           is doing is my understanding based on reading the SR.
           So I may not be accurate in everything that I said,
           but I hope that I am.
                       ACTING CHAIRMAN STEINDLER:  All right.
           Well, this chair is going to turn into a pumpkin not
           too long from now because you folks have such
           unfriendly weather.
                       DR. CAMPBELL:  As opposed to the friendly
           weather in Chicago.
                       ACTING CHAIRMAN STEINDLER:  Well, we don't
           shut the place down.
                       DR. CAMPBELL:  John.
                       DR. BRADBURY:  John Bradbury.  We have
           been talking about the ultraconservative and the
           problems with that approach.  I would like to pose a
           possibility that there is a situation where DOE has
           been nonconservative, and that relates to what was
           raised yesterday concerning the use of hydrochemistry
           in the saturated zone to delineate flow paths.

                       Again, to remind you that the line from
           Yucca Mountain down to the critical group is at
           constant chloride chemistry, chloride being a non-
           conservative tracer similar to technetium and iodine.
                       Essentially this is saying that there is
           no dilution along the saturated zone flow path. Also,
           one should consider the evidence that perched water in
           the UZ is similar to perched water in the saturated
                       So one could also think that there is no
           dilution on the whole flow path for these conservative
           species or elements.  Now, why I am saying this
           evidence hasn't been used that way is because one of
           the key attributes is delay and dilution of
           radionuclide concentrations provided by natural
                       DOE's modeling assumes or part of the
           model involves movement through the UZ and then there
           is a separate leg along the SZ, and there is a
           technique, a convolution technique, to essentially
           allow source material from the UZ to be added to the
                       So it is like throwing sticks on to
           flowing streams.  Now, the flowing streams flow at
           different rates.  So the faster flowing stream, if you
           throw it in at the same rate, dilutes the
           radionuclide.  And that is what DOE models.
                       That is not what this type of chemical
           evidence would suggest.  So here is evidence that may
           suggest that DOE's model is non-conservative.
                       DR. CLARKE:  If I understand you, John,
           you are saying that you can't have it both ways.  Do
           you have an opinion which way it should be?
                       DR. BRADBURY:  What I want to make sure is
           that all evidence is used to the point where you have
           got alternative models being considered.
                       DR. CLARKE:  Well, I guess my question may
           be better phrased by saying do you have a problem with
           the flow paths as they have been delineated?
                       DR. BRADBURY:  Well, the flow paths, the
           hydrologists say that those flow paths -- and
           hydrochemistry aside, those flow paths are reasonable.
                       I take that evidence and say that seems
           reasonable, and then when you couple that with the
           hydrochemical evidence, you come up with a situation
           where you say, well, it looks like hydrochemical
           evidence, which is evidence that is not just short
           term, but evidence that has been developed over
           thousands of years, it is really  kind of very good
           evidence to say, yes, no dilution occurs.
                       And therefore I am seeing this discrepancy
           here with regard to the evidence.
                       ACTING CHAIRMAN STEINDLER:  Okay.  Any
           additional comments?  If not, then my intention at the
           moment is to suggest we all go home.  What else do we
           need to do here?
                       DR. CAMPBELL:  I think the path forward
           for this group is that all of us agreed in our
           discussions yesterday among ourselves that we are
           going to look harder at the IRSR and do a cross-walk
           with some of the individual issues that we have
           identified in our own look-see at the various DOE
           documents and models of TSPA.
                       And that basically the group will be
           writing a report to the main committee for its
           consideration as a possible letter to the Commission.
           So that is basically the path forward for us.
                       This meeting is not the end of our work,
           but rather a halfway point, in terms of getting a
           better handle on some of the issues and interacting
           with people here.  But we have some more work ahead of
                       DR. MCCARTIN:  I was going to offer that
           Dick Codell will provide you with the paper that talks
           about this experimental evidence that I think at least
           at one time DOE was looking at and suggesting a high
           release rate.
                       ACTING CHAIRMAN STEINDLER:  All right.
           Well, thank you very much for all of your work, and I
           hope you all get home for those of you who have
           someplace to go.  And we will call the meeting
                       (Whereupon, the meeting was concluded at
           9:27 a.m.)

Page Last Reviewed/Updated Monday, October 02, 2017