Thermal-Hydraulic Phenomena - September 27, 2001
Official Transcript of Proceedings
NUCLEAR REGULATORY COMMISSION
Title: Advisory Committee on Reactor Safeguards
Thermal-Hydraulic Phenomena Subcommittee
Duane Arnold Energy Center Power Uprate
Request
Docket Number: (not applicable)
Location: Rockville, Maryland
Date: Thursday, September 27, 2001
Work Order No.: NRC-033 Pages 178-327
NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers
1323 Rhode Island Avenue, N.W.
Washington, D.C. 20005
(202) 234-4433 UNITED STATES OF AMERICA
NUCLEAR REGULATORY COMMISSION
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ADVISORY COMMITTEE ON REACTOR SAFEGUARDS
THERMAL-HYDRAULIC PHENOMENA SUBCOMMITTEE MEETING
DUANE ARNOLD ENERGY CENTER POWER UPRATE REQUEST
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THURSDAY
SEPTEMBER 27, 2001
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ROCKVILLE, MARYLAND
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The ACRS Thermal Phenomena Subcommittee
met at the Nuclear Regulatory Commission, Two White
Flint North, Room T2B3, 11545 Rockville Pike, at 1:00
p.m., Dr. Graham Wallis, Chairman,
presiding.
COMMITTEE MEMBERS PRESENT:
DR. GRAHAM WALLIS, Chairman
DR. F. PETER FORD, Member
DR. THOMAS S. KRESS, Member
DR. DANA POWERS, ACRS Cognizant Member
DR. VIRGIL SCHROCK, ACRS Consultant
ACRS STAFF PRESENT:
PAUL A. BOEHNERT, ACRS Staff Engineer
I-N-D-E-X
AGENDA ITEM PAGE
Introduction and Open Questions . . . . . . . . 181
NRR Presentations. . . . . . . . . . . . . . . . 191
Open Issues. . . . . . . . . . . . . . . . . . . 283
Concluding Remarks of Subcommittee . . . . . . . 306
P-R-O-C-E-E-D-I-N-G-S
(1:00 p.m.)
CHAIRMAN WALLIS: The meeting will come to
order. This is a continuation of yesterday's meeting
of the ACRS Subcommittee on Thermal-Hydraulic
Phenomena. I am Graham Wallis, the Chairman of the
Subcommittee, and I will immediately hand the meeting
over to Dana Powers, who is the Cognizant Member for
this meeting.
DR. POWERS: Thank you, Professor Wallis.
We are going to go quickly through the staff's version
of this application for a power uprate from Duane
Arnold this morning.
And at the conclusion of the
presentations, I am going to walk around the
membership to discuss two things. First, their
reactions to what they have heard; and second of all,
trying to develop some guidance both to the staff and
to the applicant on what they should think about
presenting to the full subcommittee in support of our
subcommittee report.
To the extent that the members have
thoughts as the presentation goes along, I hope that
they will send me notes so that I can start assembling
something of an agenda, and some idea of how long it
will take.
My opening feeling here is that right now
the central issues that will be of interest to the
full committee are the PRA results and the code audit
results from the staff, but that is just my initial
impression at this point.
I think we did have some open items left
over from yesterday's presentation by the applicant,
and I will ask Ron if he has anything that he would
like to touch on just to fill us in.
MR. MCGEE: Good morning. This is Ron
McGee of NMC. Yesterday, there were a few questions
that we looked up some material from yesterday. The
first was dealing with the scaling factors associated
with our stress calculations, and with that, I will
turn the discussion over to Al Roderick.
MR. RODERICK: I am Al Roderick, with NMC,
at the Duane Arnold Energy Center. The question was
where the 12-1/2 percent increase, the scaling factor
came from for the main closure flange, even though it
is a constant pressure power uprate.
I talked with the people that did the
detailed work, and in addition to normal operation,
they also look at all the transients that are applied,
and then the most limiting one is used to determine
the scaling factor.
So, in fact the turbine trip transient
event pre-EPU showed an 8 degree temperature change
during that event, and the analysis after, or when we
are considering EPU conditions, showed a 9 degree.
So that ratio, going from 8 degrees to 9
degrees, is a 12-1/2 percent increase. So we are
talking about a very small number, and it was
following the simple, straightforward, considerative
methodology in calculating that ratio.
CHAIRMAN WALLIS: Wait a minute. I am
concerned here because it is supported with 9.2
degrees, and as I remember, your number went up to
pretty close to the limit. You went up from -- I have
to look at the numbers.
Well, from 68 to 77 and the limit was 80.
So I now have to worry, and if you are saying that one
degree is worth this change, then was it 1.0 or 1.1,
or 1.2 degrees. What accuracy are we talking about
here? That is the cause of it.
MR. RODERICK: This is a very conservative
methodology that is being used to verify code
compliance, and the conservative scaling factors were
determined following their methodology looking at EPU
evaluations.
And the scaling factor was applied to the
current calculated stress, and the EPU stress MEDCO
allowables, and that satisfied the acceptance
criteria. So no further detailed work was needed.
CHAIRMAN WALLIS: Well, you understand my
point. You are saying 8 went up to 9, and that's 12-
1/2 percent, and one degree is 12-1/2 percent. We are
talking about 77,364, which is an accuracy of one part
in about 77,000.
And I would have to worry that if your
reason is that it went from 8 to 9, maybe it went from
7.9 to 9.1, which would take you over the limit of
80,000.
So I think we need to have something in
writing that is more rigorous. I'm sorry, but it just
doesn't sound good enough, unless the committee wants
to override me on that, but that is my opinion. Dr.
Ford is an expert on materials.
DR. FORD: Well, that was my first
reaction. That is a source of the 12 percent.
MR. WU: Good morning. I will try to
answer the questions. You have to understand that I
am the reviewer on these parts as a matter of fact.
MR. BOEHNERT: Can you identify yourself,
please, sir.
MR. WU: Okay. My name is John Wu.
According to the methods, if we have some increase,
like a transient in temperature or flow, or pressure
transient, normally you do -- you know, you develop
the factor, the scaling factor.
Then usually the scaling factor multiplies
the -- and the -- actually, if you say the temperature
increases by one degree, which means you increase
probably only -- well, only thermal, and that
increases by 12.5 -- and actually this choice
including seismic and all other LOCA.
And now because of these conservative
measures, you must multiply by the -- and the upper
multiplication after you multiply by that is then
allowable, and then we say, okay, we will not go any
further.
So actually 12.5 is only -- you know,
because of the scaling factor, is very conservative.
But it is the thermal stress -- that is only part of
that.
CHAIRMAN WALLIS: I think that must be
right. It can't be that the thermal stress is this
entire 77,000 psi.
MR. WU: No.
CHAIRMAN WALLIS: So the thermal being 12-
1/2 percent can't be the whole story.
MR. WU: Right.
CHAIRMAN WALLIS: Now, what we need is a
solid written explanation.
MR. WU: Probably they need -- it is
detailed, but this is the way they do it. They
multiply whatever the change is, and the change is
where you have the scaling factor, and you multiply it
by the -- and you are including the thermal pressure
and everything in there.
CHAIRMAN WALLIS: So I think this could be
resolved by a written communication of some sort.
MR. WU: Yes.
CHAIRMAN WALLIS: Thank you.
MR. WU: And confirmation of it.
DR. POWERS: Ron, did you have any other
points that you wanted to make?
MR. MCGEE: Not at this time. Oh,
concerning other questions left open from yesterday?
DR. POWERS: That's right.
MR. MCGEE: There was questions concerning
H202 monitoring post-LOCA, and with that, I will turn
the discussion over to Steve Huebsch.
MR. HUEBSCH: The first thing is that
there was a question -- oh, this is Steve Huebsch,
NMC. There was a question about the five percent
limit, I believe that was in the write-up.
Do you want me to go through all of that,
or did you want to specifically tailor the question to
--
CHAIRMAN WALLIS: Well, the five percent
-- maybe the staff can do it. My comment simply was
that in reading the SER the explanation seemed turgid.
I just wanted a clear explanation, and maybe the staff
will give that to us today.
MR. HUEBSCH: Well, I can go through that
real quickly if that was the intent, and the five
percent limit is out of the regulation for oxygen
limit. Duane Arnold is a Mark-I containment. It is
a nitrogen inerted containment.
So as part of EPU, we looked at the
hydrogen-oxygen generation rates, and predominantly
because of the EPU, you saw that your increases were
from two factors. One was an increase in generation
because of radiolyosis, and the second one had to do
with the redesign of the fuel, the GE-14 fuel.
So those were the two main factors that
changed the rate of generation. Duane Arnold monitors
oxygen content in order to keep the flammability
limits, because with the nitrogen containment, the
hydrogen needs an oxygen component to reach there.
So in looking at the analysis, we
identified that because of these two methods that we
would reach that 5 percent oxygen limit by about a day
sooner than we did prior to EPU.
So one of the things that we did was that
we have a containment atmosphere dissolution system
that we use to mitigate that concern, and the CAD
system on site had the capacity to increase the
quantity or the mass of nitrogen in the system to be
able to maintain that oxygen limit below five percent
for the duration of the seven days as required by the
standard.
So we increased the mass retention in that
system in order to keep the oxygen limits below the
five percent from roughly 2.3 days into the event to
the 7 day mark.
The other issue with the oxygen --
hydrogen-oxygen monitors that is in the write-up deals
with the heat trace that we have installed. Our heat
trace lower limit is 200 degrees, and so the heat
trace cycle is roughly between 200 and 215 degrees.
And from a conservative nature, we looked
at that, and what we know is that our monitors are --
they read conservatively high when the drywall or
containment temperatures are above the heat trace
temperatures.
So what we have done is that in the
submittal, we have identified that the containment
hydrogen/oxygen monitors will not meet the
requirements of Reg Guide 197, and the NUREG 0737 for
the first period of time until drywall temperatures
come down.
However, they will be operable. They will
be reading a little bit high. But we will be able to
use them for trending, and we will be able to monitor
things.
Since we don't have any actions taken for
roughly 2.3 days, we felt that a 24 hour change in the
commitment prior ot meeting the requirements of the
Reg Guide 197 accuracies was appropriate.
And as I said, we still have them, and we
will be able to turn them on and we will be able to
use them for monitoring and trending of the generation
rates, such that the control room operators will be
able to figure out when they are going to have to take
appropriate mitigation steps.
CHAIRMAN WALLIS: So they don't meet the
requirements, but it is at a time when they are not
needed. Therefore, you made that argument, and does
the staff accept that argument?
MR. MCGEE: Is anyone here from the
containment systems branch?
MS. MOZAFARI: Well, I just wanted to let
you know --
DR. POWERS: I don't think we are ready
for you yet.
MS. MOZAFARI: Well, I wanted you to know
that the containment systems, if you are going to ask
about the containment systems and analysis, the staff
is on a holiday today.
CHAIRMAN WALLIS: That's why they invited
us down here, right?
MS. MOZAFARI: The containment systems
staff, it is a religious holiday, and they were not
able to make it today.
CHAIRMAN WALLIS: I see. Okay.
MS. MOZAFARI: We talked to Paul about he
possibility of either tomorrow morning or presenting
actually in the full committee the results of the
analysis. So I just wanted to let you know that. I
am Brenda Mozafari, the project manager for the
licensing for Duane Arnold.
MR. BROWNING: I think we understand what
Duane Arnold did. We need to understand how the staff
looked at that.
CHAIRMAN WALLIS: And why it is
acceptable, yes.
DR. POWERS: That's right. Ron, do you
have any other points?
MR. MCGEE: Not at this time. Thank you.
DR. POWERS: Okay. Thank you, Ron. Okay.
We will now turn to the presentations by the staff,
and Brenda, you are going to provide us an
introduction on this?
MS. MOZAFARI: Right. As I said, by way
of introduction, my name is Brenda Mozafari, and I am
the Duane Arnold licensing project manager for NRR.
And you did receive the draft safety evaluation --
MR. BOEHNERT: Excuse me, Brenda, but you
need to speak in the mike.
MS. MOZAFARI: You did receive the draft
safety evaluation and I guess I want to emphasize that
it was draft. We felt that it would not have been a
good thing to postpone the ACRS again for purposes of
tieing it up in a nicer packaging once we because
pretty convinced that our evaluation was complete,
with a few things still left to tie up a the end.
I think that we want to present here today
the basis for the draft safety evaluation, recognizing
that there were formatting and wording errors, and
matters left to resolve. But we felt that they were
at least close to closure, and the staff is going to
present their evaluation.
The containment analysis portion, as I
said, is going to be addressed later, but I believe
that George Hubbard was going to be here today if
there were any general questions.
And I want to give you the order of
presentation. Ralph Caruso, who is the section chief
of reactor systems, is going to speak first on the
reactive core fuel performance area.
Then John Wu will discuss material
degradation issues, and he will be supported by
members of the materials engineering staff who are
here to support him.
Then we will do the PRA review and ATWS
response, and Donald Harrison is here to present that,
and Dick Eckenrode is going to provide additional
information on the human factors portion.
We do have two open issues at the time of
the draft safety evaluation. They have to do with
start-up testing, and I will give you a brief summary
of where we are on that, and the NPSH issue that was
left to open.
And Kerry Kavanaugh is going to discuss
that. And then we will give some overall concluding
remarks at the time. So I am going to turn it over to
Ralph at this time.
DR. POWERS: Let me ask one question. At
what point do we discuss grid stability?
MR. CARUSO: I'm sorry?
DR. POWERS: At what point do we discuss
grid stability?
MR. CARUSO: Grid stability?
MS. MOZAFARI: Well, we don't have a
specific presentation on grid stability. We could
make people available at the end of the discussion to
discuss that.
DR. POWERS: Okay.
DR. SCHROCK: I have one point that I
would like to bring up and that is something that is
not on the agenda here, and concerning LOCA
evaluation.
I think that the presentations so far have
indicated that the increase in the peak clad
temperatures is very modest, and that there is a huge
gap remaining between the peak clad temperature and
the 2200 degree limit.
But I was reminded that the SAFER method
application under SECE -- I think 472 was the number
-- resulted in a 1600 degree limitation being imposed.
And so I think the wrong impression has
been conveyed and I think that ought to be clarified.
So where do we really stand with regard to what is the
existing peak clad temperature limit in LOCA for Duane
Arnold.
And what was it previously under the old
license provision, and what would it be under the
extended power uprate? So I think that another look
at the comparison of those numbers is really in order.
MR. CARUSO: This is Ralph Caruso from the
reactor systems branch. This was discussed quite a
bit yesterday I thought by GE when they explained
under the SAFER/GESTR methodology that licenses have
to meet both the 1600 limit and the 2200 limit.
And I don't have the actual numbers here,
but they provided the pre-and-post power uprate peak
clad temperatures for both of those aspects of the
methodology, and showed that the numbers did not
change significantly, I believe, either one of them.
I guess I am not clear. Dr. Schrock, what
your question is.
DR. SCHROCK: Okay. Perhaps I am the only
on here that had this impression of the results as
presented. Both in the meeting yesterday and in the
previous meeting on this topic, there was discussion
about the large range above the predicted peak clad
temperatures which is available.
And it was presented in the sense that
2200 is the applicable limit, and 2200 is the
applicable limit in Appendix K and that is true. But
you have also imposed the 1600 degree limit for this
particular licensing methodology.
And also it was mentioned that, yes, there
are some plants that do in fact have predicted peak
clad temperatures close to the 2200 degree limit. But
in fact those plants are not analyzed by this method.
So what I am saying, Ralph, is that I
think this is a matter which was presented in an
unclear way, and I am asking for clarification. Now,
if I am the only one that sees it that way, fine, it
doesn't need any. I will then have to ask my
colleagues if I alone in this?
MR. CARUSO: Let me see if I can explain
it again. They have not just one limit of 1600, but
they have to meet both the 1600 according to the upper
bound calculation; and they have to meet 2200 by the
licensing basis calculation.
They do essentially two sets of
calculations, and they have to meet both of those
criteria. They cannot just meet one or the other.
They have to meet both, and they have to demonstrate
that they meet both.
DR. KRESS: Would you remind us of the
reason for the 1600 degree limit?
MR. CARUSO: The 1600 degree limit came
because the data that was used to support the
methodology did not include tests that went above the
1600 degrees.
DR. KRESS: So that was the basis then?
MR. CARUSO: So that was the reason for
the limit. Recently, GE has asked us to relax that
limit because they have some new data, and we are
considering that.
But right now the methodology, and
methodology comprises a lot of different parts, but
the methodology does include both an upper bound
calculation to show that they meet the 1600 limit,
plus an Appendix K type calculation to show that they
meet the 2200 limit. So they have to meet both of
those.
CHAIRMAN WALLIS: And the nomenclature of
upper bound is a little bit confusing, because it is
actually the lower one.
MR. CARUSO: Right, and I understand that.
MS. ABDULLAHI: If I may interject. I am
Zena Abdullahi, of the reactor systems. And I just
want to say that the Duane Arnold numbers -- and I
think that GE and Duane Arnold can expand on it, but
that the 2200 limit for Duane Arnold for the GE14 fuel
is 1510, and which is the limiting, and it is 1350 for
the 1600 limit, or less than 1350.
CHAIRMAN WALLIS: That's what we had
yesterday, and it was one of the unnumbered slides.
It is useful that they have numbers so that we can
refer to them.
MR. CARUSO: Right. I guess I am not sure
that I have answered your question, Dr. Schrock.
DR. SCHROCK: Yes, I think you have.
MR. CARUSO: Okay. Good morning. My name
is Ralph Caruso, and I am the Chief of the BWR Nuclear
Performance Section in the Reactor Systems Branch of
the NRR, and I am going to talk this morning about the
fuel and the reactor systems review that was done for
the Duane Arnold power uprate.
I would like to start by giving you a bit
of background. This power uprate was not just an
increase in power for the Duane Arnold plant. It also
included a change in fuel to GE14, which is one of
GE's newest fuel lines.
And it also included a change in the power
to flow map to use what is called MELLLA operation, M-
E-L-L-L-A, maximum extended load line limit analysis
method, which is needed in order to be able to get to
the higher power level.
However, I wanted to make it clear before
I start, and I will say this several times throughout
my presentation, that even though the power limit was
-- that the power will be changed at Duane Arnold, we
are making no changes to the fuel burn up limits.
BWR fuel is licensed to a certain burn up
limit, and that limit has not changed. And in
addition licensing limits have not changed as a result
of this.
So Duane Arnold has to demonstrate -- and
we believe that they have demonstrated that they meet
those licensing limits for this power uprate.
DR. POWERS: To be clear on this, it seems
to me that it is also true that the staff has made an
engineering judgment that at the license burn up limit
on the fuel that the fuel will tolerate the ATWS
transients, and that that has not been demonstrated by
experiment.
But that a research program has been
initiated to try to confirm that regulatory decision.
MR. CARUSO: I believe that is a fair
statement to make, Dr. Powers. The review scope, we
looked at the core, the fuel performance, reactivity
characteristics, and all the aspects that we would
look at during the normal review of this sort of
scope.
We used as a template for this review the
ELTR-1, ELTR-2, and the supplement to ELTR-2, that
were reviewed and accepted by the staff earlier, about
5 or 6 years ago, for power uprates.
The analyses in the evaluations that were
done by Duane Arnold and by GE are based on NRC
approved methodologies, analytical methods, and codes,
including the acceptance criteria that are described
in those methods.
Because this was a rather large power
uprate, we decided that we would include on-site
audits as part of our review. Duane Arnold was the
first plant that we had done this for for a power
uprate.
I am going to report that we found the
process to be quite positive and useful, and we intend
to continue to do it. We looked at the safety
analyses, and the performance evaluations that were
prepared by GE and by the licensee.
And we determined whether they complied
with analytical methods and codes that I have
discussed earlier, and we used the EPU safety analysis
report, NEDC-32980, as the guideline for this.
CHAIRMAN WALLIS: How does this audit
work? Do you look over their shoulder while they ran
a calculation or is it a formal process where they are
on one side of the table and you are on the other?
MR. CARUSO: No, we send a team, usually
4 to 5 people, to the offices where the information is
located, and GE has different parts of their
organization doing different parts of their analyses,
either in Wilmington or San Jose.
And what we do is that we look at what has
come in, and we look at what we have looked at
recently, because we take history into account; the
history at other plants, and the history in other
reviews.
And we say to ourselves where do we think
there are areas where we maybe don't feel comfortable,
but where we would like to look. And we target those
particular areas, and we say, okay, licensee, where is
this information located.
And then we send a team of 4 or 5 people
out there, and they will say that I want to look at
the design record files for the ATWS analysis for this
plant.
And at this point in the review those
analyses should already be completed. There should be
a set of analyses that has been reviewed, approved,
quality assured, and documented. And we ask for those
design record files.
And this team of people will sit down in
a room for a day or two, and jus read, and think, and
read, and think. And at the end of a few days, they
have questions.
And they go to the GE people and say I
don't understand this, and where did this come from.
Why did you make this assumption. Can you document
for me that the operators will take this particular
action.
CHAIRMAN WALLIS: Like a Ph.D. defense.
MR. CARUSO: That is the idea, and because
the experts are right there, these audits are
particularly effective. They can ask the question and
they can get an answer right away. So that is the way
that we do them.
A lot of this is background about what the
criteria are,. and in the standard review plan,
Section 4.2, that talks about fuel system design
criteria for AOOs, and I believe that the criteria is
that during AOOs that 99.9 -- 99.9 and not 99.99 --
percent of the fuel will not undergo transition
boiling.
That damage would not prevent control rod
insertion, et cetera, et cetera, et cetera. GE has a
methodology that has been approved to ensure that
analyses of AOOs demonstrate that they meet this
criteria. That is what we looked at.
In addition, the vendors perform thermal
mechanical, thermal hydraulic, and neutronic analyses
of the fuel to ensure that it meets the design limits
that are specified as part of the fuel licensing
criteria.
The fuel licensing criteria are another
set of or is another document which allows the vendors
to design fuel, to build it, and to use it in
reactors. So we review the application of these
methodologies to the plant in question, and in this
case, Duane Arnold.
DR. POWERS: Is this the appropriate point
to ask about the COBRA-G evaluation of GE14 fuel?
MR. CARUSO: I'm sorry, the COBRA-G?
DR. POWERS: The COBRA-G, yes.
MR. CARUSO: I will get into that in a
second.
DR. POWERS: Okay.
MR. CARUSO: I am still to a certain
extent in background here, and I am going to try and
move along. The thermal limits evaluation for Duane
Arnold was performed using what is called an
equilibrium core.
They will establish an operating condition
that is expected to occur after a certain number or
reloads, where the plant is essentially operating in
a steady state mode.
It has completely been loaded with the
particular type of fuel, and in this case, GE14 fuel,
and it is operating from one cycle to another cycle at
the -- how do I want to say this -- the term is the
equilibrium core.
And which is the state that you reach
after you load the same type of fuel using the same
core design parameters over a number of cycles, and
eventually reaching an equilibrium state in terms of
core design. And once again operation -- considering
the MELLLA rod line and the 20 percent power uprate.
One thing that I would like to mention is
that although these analyses were done for an
equilibrium core, thermal limits are established or
confirmed for every individual reload, because you
don't have the equilibrium core starting from the
first core.
So GE or any other vendor, they do thermal
limits analyses to verify that the core as designed
and as installed meets those thermal limits. And they
publish the results of those analyses in something
called a cooperating limits report.
And very often they have to submit to us
a techs spec change because they change a parameter in
the tech specs called a safety limit minimum critical
power ratio.
And we have actually done the review of
that safety limit ratio for Duane Arnold. I think I
signed it out the other day. And that is a number
that varies between about roughly 1.09 and 1.12 or
thereabout.
And the methodologies for establishing
that number are well understood, and we do that review
just about every cycle. And once again I want to make
it clear that there are no changes to any burn up
limits for this fuel.
A power uprate does not allow anyone to
exceed currently established burn up limits.
DR. POWERS: And I will hasten to add
again that those are based on a judgment that they
will in fact survive reactor transients.
MR. CARUSO: I understand that. I am
trying to make this point as often as I can because
some of the questions that have arisen imply, or
actually state that, well, because you are going to do
a power uprate that the fuel is going to be burned to
a higher burn up value.
And I want to make it clear that that is
not the case. The fuel may be burned faster and some
of the fuel may experience a higher duty than it would
otherwise see. But the actual burn up limits, the
amount of gigawatt days per metric ton that you can
get out of the fuel, has not changed.
DR. KRESS: The average has changed
though?
MR. CARUSO: The average has changed, but
the peak bundles, the bundles that are most limiting
in these analyses, have not.
DR. KRESS: Yes, most limiting, in terms
of the regulatory compliance with Chapter 15 DBAs.
MR. CARUSO: That's correct.
DR. KRESS: But when we think about PRAs
and risk, we think about the average.
MR. CARUSO: That's correct. The decay
heat has indeed gone up. So there are some scenarios,
for example, of shut down cooling, where there is less
time available.
I believe there was a significant
discussion about that yesterday, and that situation
does exist. But for fuel licensing, those limits have
not changed.
I have a lot of background here on
stability. I don't want to spend a lot of time on it
because we have talked about this quite a bit
yesterday. Let me see if there is any slide here that
I need.
CHAIRMAN WALLIS: Are you going to come
back to this business of the up-skew and down-skew?
MR. CARUSO: I am going to get to that.
CHAIRMAN WALLIS: Okay.
MS. ABDULLAHI: Ralph, I think you passed
that under the on-site audit.
MR. CARUSO: Let's see.
MS. ABDULLAHI: You have to excuse us. It
is not numbered.
MR. CARUSO: I thought I had a slide in
here that talked about that, and I was going to be
getting to that.
MS. ABDULLAHI: I think you passed it
already, Ralph.
MR. CARUSO: I did?
MS. ABDULLAHI: The staff EPU audit, and
it is right after fuel design and operations.
CHAIRMAN WALLIS: That's the one that I am
looking for.
MR. CARUSO: Oh, okay.
CHAIRMAN WALLIS: That is the one that you
kept saying that you were getting to, and you left it
behind.
MR. CARUSO: I'm sorry. You know what?
I think it mis-fed through the feeder, and I don't
have that slide as a slide. Okay. What I did -- I
have the printouts here, but I have a set of slides,
and I think maybe it got double-fed. So I didn't get
a copy of that one. So I don't have a slide for that
one. But I can talk from it.
One of the reviews that we looked at, one
of the areas that we looked at during the review was
the fuel system design. In this case, for GE12 and
GE14 fuel.
And during the course of the review, we
discovered that GE had used some data that was
generated by a code known as COBRA-G to be included a
database for a correlation that is known as GESTR-14.
I think it may have been known as GESTR-10 at the
time.
And as part of the review, we actually get
into the details of these correlations. We look at
the data, and we say where did this data come from.
We can look at the quality assurance for
it. And in the case of this one particular heat
transfer correlation, the staff discovered that some
of the data did not come from a test facility, but
came from a computer code.
And we questioned that, and we held some
pretty intense discussions with General Electric about
this. And in the end, we convinced them that they
should not use this data. And as a result, what they
have done is that they have backed it out of their
database, and they have revised their correlation.
And they have followed their procedures in
their corrective action plan to revise the correlation
and redo assessments or calculations as necessary to
reflect those changes. It is the same sort of thing
that they would do if they discovered an experimental
data was not correct.
So as I say in this slide, we believe that
they are taking appropriate action. They have taken
appropriate action, and we think that this issue is
resolved for Duane Arnold.
Yesterday though I received -- actually in
this room, very room, I received GE's submittal from
Glen Wattford who is sitting somewhere in the back
there, with new information about this correlation.
And the staff will be reviewing it. They
have gone out and they have additional data available
that they had not used in this correlation.
They have decided now to use that data,
and they made a staff submittal, and the staff will
review it. But I want to point this out because this
is an example of the sort of information that we have
discovered as a results of this on-site audit that we
would not necessarily see as part of an in-office
audit, for example, or a review in the office. So
that is one of the successes of this.
CHAIRMAN WALLIS: I think it is also good
that they have submitted a document, and I think we
often get uneasy when a matter is resolved by a
promise to take appropriate action, and we don't have
a process for checking that it has actually happened.
MR. CARUSO: Well, I will leave it at
that, and I will agree. I think in this case that GE
and the licensee have been very cooperative. We have
honest technical disagreements, and honest differences
of opinion on this.
But in the end, we convinced them that our
position was the correct one, and they have processes
to deal with this, and they followed them. Let's see.
What else.
DR. POWERS: What I did not see in the
discussion in the SER was the adequacy and
applicability of the data that were accepted by the
staff, especially with respect to power profile.
MR. CARUSO: That actually gets treated as
part of the methodology. They have to take
uncertainty penalty factors. If you don't have enough
data to support a particular profile, then you have to
take a penalty factor for that. And that is in the
methodology.
One of the questions that has come up
about these power uprates is margins, and who owns the
margin. I think there was a discussion about that --
was that this morning. No, yesterday.
DR. POWERS: Well, I think it is not only
a discussion that took place yesterday, but it is a
discussion that has taken a long time, and I think
that everybody at the table agrees. So I would
suggest that you just move on.
MR. CARUSO: Fine. Stability. As I said,
Duane Arnold is a 1-D plant and they do detectance,
suppress --
DR. POWERS: Let's be clear. 1-D does not
mean that they are one dimensional.
MR. CARUSO: That's correct.
DR. POWERS: In fact, they are a multi-
dimensional plant, and 1-D is an option corresponding
to the ATWS.
MR. CARUSO: They are an Option 1-D plant,
and the solution to the stability issue for Duane
Arnold involves implementation of Option 1-D. As part
of the on-site review, the staff discovered a document
which questioned the applicability of the generic
Divom curve.
The Divom curve is -- and I am going to
need help on this at some point if you get too much
into the details, but it is the delta CPR over initial
CPR, versus oscillation magnitude curve, and it is a
generic curve which is supposed to be applicable to
all BWRs, which is an input to the on-line stability
monitoring systems.
And during the review the staff discovered
an internal GE document which questioned whether the
existing Divom curve was applicable or appropriate for
plants. And this also applied to any plant that used
GE14 fuel.
And as a result, GE has issued a Part 21
report on this Divom curve, and the number of plants
-- all the BWRs in the country are in the process of
responding to that Part 21 notice by either taking
corrective action to go back to interim manual
corrective actions, where they have on-line stability
monitoring systems for the use of interim conservative
versions of the Divom curve.
This is an ongoing process, and let me see
if I have the slide here.
CHAIRMAN WALLIS: So actually the core-
wide oscillation is one-dimensional isn't it?
MR. CARUSO: No, I don't want to say that.
It is core-wide. I don't know that I would say that
that is one-dimensional.
CHAIRMAN WALLIS: Okay.
MR. CARUSO: Okay. As I say here, GE
discovered that the generic regional mode Divom curve
is strongly affected by the peak bundle power, and
there may be some plants operating with high peak
bundle powers, where the Divom curve did not consider
that they could be operating.
GE has recommended that licensees use a
particular figure of merit to determine whether they
have a problem in this area. For Duane Arnold, that
particular figure of merit is such that the Divom
curve for Duane Arnold continues to be appropriate.
I don't believe that they will have to change their
Divom curve.
So for Duane Arnold, this is a resolved
issue. For a number of other plants though,
additional calculations will have to be done, and this
is being done under the egis of the BWR Owners' Group.
And yesterday, or two days ago, excuse me,
they presented us with a plan for redoing the
calculations and redeveloping the Divom curves. And
that plan takes into consideration individual plants'
needs and fuel that will be loaded into the plants,
and I believe it has completion date of sometime late
next year.
The staff will be receiving a submittal
sometime in the late second quarter of next year, and
hopefully we will complete our review by the end of
the next calendar year.
This is another example of an issue that
we discovered as a result of an audit that we would
not have otherwise have found.
CHAIRMAN WALLIS: What is the basis of
this Divom curve?
MR. CARUSO: I am going to ask for help on
that.
MS. ABDULLAHI: GE should address that in
this case.
MR. POST: This is Jason Post of GE.
Their TRAC-G calculations is a fully coupled
calculation, and each peak of a growing oscillation
produces an oscillation magnitude, and TRAC directly
calculates CPRs.
So you have a CPR change versus an
oscillation magnitude, and we normalize those factors
to produce the Divom curve.
CHAIRMAN WALLIS: So it is an entirely
theoretical --
MR. POST: Yes, it is theoretical, and of
course TRAC-G has been used to benchmark actual
instability events, and so we are pretty confident
that it does a good job of doing that.
CHAIRMAN WALLIS: Oh, it has been
benchmarked against oscillatory events?
MR. POST: Yes. Yes, it has.
DR. POWERS: Were there others?
MR. POST: There were some KLL specific
tests that we benchmarked, and there was another event
in Cofrontaes (phonetic) that was an unplanned event
that we benchmarked.
There were also some earlier events at
Caruso in Italy. So there were a number of overseas
events that we benchmarked.
MR. CARUSO: Jens, did you want to say
something?
MR. ANDERSON: This is Jens Anderson.
Yes, I just wanted to make a comment, but I think
Jason made most of the comments, and there have been
a fairly extensive qualifications basis.
Maybe one additional point that I would
like to make is on oscillatory testing, and ATWS
capability --
MR. CARUSO: Okay. As part of all of
these reviews of fuel, the staff also considered the
operability of the supporting systems. For example,
the ECCS system, the RCS system, the recirculation
system, to make sure that these systems are not
operating outside their design basis, and could
provide appropriate support to the reactor so to
speak.
So this was part of the standard review,
and we did not identify any particular operation of
any of these systems that would call into question
operation at the higher power level.
It should be noted that some of these
analyses will continue to be rerun throughout the life
of the plant as the core reloads change, and as the
limiting transients and accidents change through the
life of the plant.
So even though we have done this review at
this point, and the licensee has documented their
analyses, those analyses continue through the life of
the plant.
One of the audit calculations that we
looked at was the ECCS analyses for Duane Arnold. We
looked at the methodology of SAFER/GESTR, and the
results, and we didn't discover any problems. It was
clean.
One of the systems that I think people
have been concerned about has been the standby liquid
control system because of its importance to the ATWS
scenario. Standby liquid control is a manually
operated system.
The license confirmed to us that it can
actuate, and it can inject the required amount of
boron into the system when called upon to do so. We
believe that they have demonstrated that the SLC
system would be able to inject the required amount of
boron into the reactor vessel during an ATWS.
This is a conclusion concerning reactor
transients, and just a description of the fact that
they did do the analyses, and they will reanalyze them
and reconfirm the results for every particular reload,
and they used approved methods, and the results met
the acceptance criteria.
For ATWS, they met the ATWS mitigation
features. 10 CFC 50.62 specifically requires the
installation of alternate rod insertion, and reactive
recirc pump trip, and standby liquid control boron
injection capability, and they meet those
requirements.
One of the questions that the ACRS asked
was whether there should be an automatic standby
liquid control system installed. In looking at this
matter, my recommendation at this point is, no, I
don't want it.
And we have identified a scenario which --
well, I don't want to overstate this because we are
just in the very early stages of looking at this. But
if the standby liquid control system initiates too
soon during a transient, there could be difficulties
that are caused by actuation too soon because of the
way that the system is piped, and the way the relief
valves in the system are installed.
So automatic actuation of the standby
liquid control system is something that would need to
be considered very carefully.
CHAIRMAN WALLIS: Well, if it is done too
soon, it could be programmed not to do it too soon.
And you have the same problem with an operator doing
it too soon.
MR. CARUSO: That's correct.
CHAIRMAN WALLIS: And between the operator
and the automatic, it is not really based on having
discovered a new scenario.
MR. CARUSO: Well, actually, if you do it
automatically, you have to think about the timing, and
what sort of signals cause the actuation.
Operators are not as reliable as automatic
actuation systems. They take a while to react and to
respond, and we hope that they think about what they
are doing. So there is a certain amount of delay
there.
But we are reluctant at this point to say
that there should be an automatic standby liquid
control system actuation. I'm sorry, a question?
AUDIENCE: What defines too soon? Is it
10 seconds, 5 seconds? Does anybody have a feel for
that?
MR. CARUSO: Well, looking at the pressure
traces, it looks like it is within five seconds or so
after the initiation or the detection. I believe
there is a signal called an ATWS alarm, or a ATWS
signal, that occurs.
And I don't think you would want to have
the standby liquid control system initiate off of that
particular signal. I don't want to get into this in
too much detail because it is something that we just
recently discovered, and we have not thought about it
very much.
DR. POWERS: I would like to go back to
your existing recovery, and recommended recovery
process for an ATWS. The strategy of dropping the
core level and injecting boron, and bringing the
coolant level back up was developed considering a
particular core power profile that was common at the
time that the strategy was developed.
We don't have that particular power
profile now in the plant. The collapse liquid level
is actually being dropped down below the top active
fuel in this strategy.
How does the revised power profile that is
being envisioned for Duane Arnold and the power uprate
affect that strategy?
MS. ABDULLAHI: I think that GE would like
to make a response to this issue, and then I would add
if need be.
MR. POST: This is Jason Post. The
dissolution was originally developed, including
MELLLA, and if you take a recirc pump -- the impact of
MELLLA is that Duane Arnold could operate at 99
percent of their new rated power, or I'm sorry, a
hundred percent of their new rated power at 99 percent
flow.
Previously, any plant with MELLLA could
operate at the point corresponding to 105 percent
power uprate at 81 percent of their license flow. So
those are an equivalent rod line, and if you take a
pump trip from either one of those two cases.
And a flow run back to the natural
circulation point, you end up at very close to the
same power level, because it is really controlled by
what the rod pattern, and that is what sets the power
level at the end of the run back.
DR. POWERS: You will be stunned at how
little of which you just said I understand.
MR. POST: Sorry about that.
DR. POWERS: I got all the articles, but
none of the nouns in there. It didn't make any sense
to me at all.
MR. POST: We had a power flow map up
yesterday.
MS. ABDULLAHI: If I can interject and
maybe if it would be of any help, in the ATWS
stability generic analysis that were done, they were
based on certain powers, and certain power densities,
and rod lines.
And the power, for instance, that they
were based on if I recall -- and it is seen in a table
called 5-1, it was 33233138, and that power level
compared to Duane Arnold is higher.
And then if you look at the power density,
it seemed high, and whether Duane Arnold's now would
be higher than this, I can't confirm right now. But
just to give you an idea that these bounding analyses
could have had some basis that covers it.
DR. POWERS: I think what you are telling
me is that the analyses were done for plants with much
higher power than what Duane Arnold plans to go to
originally.
The issue, of course, is how about the
power density in the froth region, or two-phase
region?
MS. ABDULLAHI: I would also have Tony
Ulses intervene as well.
MR. ULSES: This is Tony Ulses of the
staff. Actually, if I understand your question, Dr.
Powers, you are really questioning the effect of
lowering the water level to down low and whether or
not these new operating strategies would affect any of
the assumptions that went into the acceptance of that
original philosophy.
Is that the question really that you are
asking?
DR. POWERS: That is basically the
question. My recollection is that when the strategy
was originally proposed the staff resisted the concept
of bringing the collapsed water level down below the
top of active fuel.
We had a particular power level in that
phase region for those discussions. Now we have a
different one, and does it change the discussion.
MR. ULSES: This basically goes into the
concept of what is called the minimum steam cooling
reactor water level, which is basically what we say
you can go down to, and you will still have enough
flow of steam to keep the upper portion of the fuel
cool.
And if you look at how that was generated
-- and if I get off-base here, Jason, let me know.
But what I recall is that that was actually calculated
with an extremely conservative top peak axial power
distribution, which is even larger than what they are
going to go to with these modern reactor operating
strategies.
So therefore they will still be covered by
the existing minimum steam cooling reactor water
level, and so that will still be applicable.
DR. POWERS: Is this the result of an
analysis, or is this the result of your impromptu
speculation?
MR. ULSES: This is the result of a
calculation that was done quite a bit of time ago. I
believe it was like in the '80s or the '70s as I
recall when this original concept was originally
developed.
MR. POST: The mid-1980s.
MR. ULSES: The mid-1980s, and it has been
used ever since in the ATWS operating strategies.
DR. POWERS: I am quite sure that you have
not -- that you did not anticipate in that calculation
what Duane Arnold was going to do with their power
profile.
MR. POST: This is what I was trying to
say earlier. Right now at their extended power uprate
with the MELLLA line, Duane Arnold could go between 99
percent and a hundred percent of rated flow.
Previously, if they would have had MELLLA
at this power level, they could have operated it at
this point, which would be 81 percent of their flow.
These two points are on the same rod line.
So if you take a pump trip from that
point, or a pump trip from this point if they had
operated with MELLLA, both of those pump trips would
run down to the same point at natural circulation, and
basically at that point right there.
So both conditions end up there, and since
plants had MELLLA when we developed that solution
originally, we were modeling a condition that is the
condition that Duane Arnold is moving to today for
their application.
DR. POWERS: Thank you.
MR. CARUSO: I guess that's all I have to
say about reactor and fuels. If you have any
questions, I am available, or we can go on to the next
presenter.
DR. POWERS: Do the members have any
additional questions they would like to ask about
reactor fuels? If not, I think we can go on.
MR. WU: My name is John Wu from NRR, and
I am here today for this material degradations.
Actually, this material degradations is mostly
materials and parts, and it seems that my part is the
flow induced vibration is one of the issues that has
come out.
So that's what I am here for. And so that
is what I am going to cover, is this topic, and others
related to corrosion and erosion I will give to the
material people over there.
And first of all, we start with the
reduced power uprate, and I think that this flow
induced vibration mostly was covered by GE yesterday,
and so I will just quickly go through this and take
any questions if there is any.
This power uprate mostly -- while the
reactor pressure has no change, there is no change on
temperature, and no change on the flow rates, or core
flow rate.
And also there is no or very little change
in the drive flow because we generated more steam, and
we have a bigger pressure drop. So the drive flow is
increased a little, which I understand is 2.5 percent.
And mostly we have a steam flow increase.
So because there is no core flow increase, and if you
look at the component inside of the reactor affected
by the core flow, such as the guide chip, et cetera,
those become -- and also the in codes, they are the
code -- like the fuel banding, they are not affected.
But only a few components are affected,
like the drive flow at 2.5, which is very minimal.
But GE have been varying those based on their recorded
data.
And the results come up to the results
that the vibration level is below the acceptance
limits. That is the acceptance limits of -- they have
vibration -- you know, they can monitor and the
calculation illustrates the vibration stress level,
which is less than the endurance limits. That is what
GE put on it as being the criteria.
And based on that the endurance limits are
acceptable, and anything in other components -- you
know, every component, if their vibration is less than
endurance limits, and it means that they are not
getting into the picture of a particular calculation,
because the fatigue factor -- the cumulative factor,
or the cumulative fatigue usage factor is not required
in the design basis, and is zero, and it is below the
acceptable limits.
And as a matter of fact, in the GE
submittal, they put acceptable -- for 10 KSI, but that
is very conservative compared to ASME 13.6 KSI. So,
7.6 KSI if you look at the fatigue curve in the ASME,
you will see that corresponding to about 10 to the
11th endurance limits.
So, therefore, in the upper -- steam flow
affected by the increase of steam flow are the
components of dryer and separator. I think that GE
made a presentation yesterday that the dryer and the
separator there are not -- they are not separate
components, and that is mostly that they don't have --
for that.
But since we asked the question how is
this affected by flow induced vibration, they look at
their data for the separator, and the separators data,
the data for the separators, the data shows that the
vibration acceptable level is about 15 percent of the
acceptance limits.
CHAIRMAN WALLIS: We heard yesterday that
there were cracks observed in these devices. So it is
acceptable for some things, but you have --
MR. WU: There is no crack on the
separator, but the dryer, in the dryer, they did find
some, and they also looked at the dryer.
DR. FORD: Did you during the analysis
-- and I recognize that they are not safety related
components as such, but in relation to what was
discussed yesterday by GE, they are not safety related
components, the dryers and separators.
If they did fail either by stress
corrosion cracking in the channel, in the bottom of
the dryer, or by fatigue of the vains in the dryer,
and they came lose, how would that affect the overall
safety of the reactor as such, and was that evaluated?
MR. WU: Yes, we also asked the questions,
asked GE the same question about it. The design
criteria, as such, the dryer has to stay intact, and
structure integrity has to be maintained.
During a pipe break, or during the steam
line break because worrying about the dryer, goes to
the steam dryer, and -- you know, it stops the
operation, and so that has to be calculated to ensure
that structural integrity of this dryer.
And also because the power uprates, we
evaluate those to meet the design basis, and we
approve in the ELTR-1 and ELTR-2.
CHAIRMAN WALLIS: I guess my comment went
to the consequences of these things failing, and you
are telling us that the consequence that you worry
about is the pieces go down the steam line?
MR. WU: Yes, that is what a design
criteria --
CHAIRMAN WALLIS: Could they not go around
in the --
MR. WU: No, the flow induced vibrations
is what you are talking about.
CHAIRMAN WALLIS: Where do the pieces go
when they break?
MR. WU: Well, there is no problem with
that. We still try to ensure integrity during
operation, and such as like -- well, I think GE looked
at similar plant, and they didn't find a crack on this
dryer.
CHAIRMAN WALLIS: I think the problem that
we are all having is regardless of what the codes say,
there have been failures by stress corrosion cracks
and flow induced vibration in the steam dryer
separator units.
MR. WU: I am not sure it is from the flow
induced vibration.
CHAIRMAN WALLIS: Well, regardless of
whether it is flow induced vibration, or whether it is
stress corrosion cracking, they failed, regardless of
what the codes say.
MR. WU: Yes, they failed.
CHAIRMAN WALLIS: And so actually the
codes don't really mean much as far as maintaining
integrity, and the question we are asking from a
safety point of view is if these things come lose,
what do they do?
MR. WU: So that is why we are looking at
if those things come lose or will come lose, and if
not, then we don't have to worry about it. So that is
-- well, we look at what are the reasons for the dryer
to fail or crack.
I think that what GE found out was that
the crack was due to turning the turbine off, and
closure, and the flow trenching, like the TSB closure,
and --
CHAIRMAN WALLIS: I still have trouble
relating the answer to the question.
MR. WU: Well, that is what I am trying to
address. The crack is not due to -- well --
MR. KNECHT: This is Don Knecht from GE
here. Let me try to add some clarification here.
There is a couple of points. One is the cracks have
been found in the dryer assembles have all been
identified early enough that they can be repaired so
that they don't become a lost part during the upcoming
cycles.
And so there has never been a case where
there has actually been a lost part from these
components. Now, if it did happen for some reason,
the cracking is generally in the lower part of the
dryer where the conditions are more conducive to
stress corrosion cracking or vibration fatigue.
And failures in that location are going to
stay below the dryer and not reach out in that area
and into the steam line. They are not -- unless they
are very, very small, they are not going to drop back
through the separator under the conditions where we
have low power, and we are shut down or what not.
And even if they did, they are not going
to find their way all the way down into the fuel area
where they will cause damage. So we have not done
formal lost parts analyses on these, on the dryer
pieces, at least not that I am aware of.
And the size -- well, the parts that might
be lost because of this cracking are most likely large
enough that they would not cause a problem and that
would get out of the dryer area. So I hope that
clarifies it.
DR. FORD: I don't know who to address the
question to now, but there have been, for instance --
and still sticking to that one unit, there have been
stress corrosion cracking of the brackets that hold
the steam dryer assembly up.
What would happen -- those are not
protected currently by --
MR. KNECHT: Correct.
DR. FORD: What would happen because of
the general stressing nature, and increased by 31
percent -- and I think that was the number that was
given for the dryer, what would happen if you got a
whole dryer that fell down?
And I recognize that would be an extreme
event, but what would happen then? It wouldn't be
just a small part. It would be a thumping great big
component. Is that possible?
MR. KNECHT: Well, it only requires 3 out
of the 4 support brackets to hold a dryer. So if
there was cracking in one of them, that would be
detected and repaired, and that would not be a
problem.
Now, if for some strange reason you had
multiple failures, the dryer would settle, and there
would be a noticeable decrease in steam flow, and an
immediate shutdown of unknown conditions.
DR. FORD: If it was laying on top of the
separator, it would just sit there?
MR. KNECHT: Well, you wouldn't have the
steam flow that you would expect.
CHAIRMAN WALLIS: Would it make that much
difference to the steam flow? Would it just be
diverted, and increase the pressure drop, but that's
not a significant component of the overall pressure
drop is it?
MR. KNECHT: Well, normally it only has a
very small pressure drop, but I think it would a flow
blockage. But a complete one, of course, but it would
be --
MR. WU: But this is for the same --
according to their submittal, the occurrence occurs at
the outer bank close to the impact nozzle, and -- is
four times of that, and so there is no history of that
for the Duane Arnold.
So, either there is no such thing, or is
there no history for the -- is already 113 percent. So
if we wanted to look at the operating experience, the
cracking -- and we can ensure that it is okay. And
here we are looking at flow induced vibrations to see
if there is anything like that.
And there is no data and we looked at the
dynamics of a pressure drop -- and it is about 10
percent of the -- and so the flow increase 20 percent,
and the vibration level increased 50 percent. So,
that is 1.7 or about -- and so you can say that you
can get some reasonable assurance --
CHAIRMAN WALLIS: You are saying that it
is far from its endurance level?
MR. WU: It is far from their margin with
respect to the dryer, yes. And the flow separators
did not vary. The separator is about 15 percent
according to their data -- and if it were to increase
by 50 percent, you would have about 22 percent. So
that is a big margin there, and because of this big
margin, it gives us a good feeling about this.
CHAIRMAN WALLIS: Well, have they tested
these dryers and separators at the specific conditions
that they are going to be operated at with the power
uprate in separate effects tests?
I think we asked that question yesterday,
and I believe the answer was yes yesterday, and it
seemed to be a very quiet yes. I mean, that's what I
would to see.
I mean, flow induced vibrations, there are
resonances and things that happen, and when you scale
up this is based on some assumptions, and it is much
more reassuring to say we have actually run this
thing, and we have measured the vibrations under the
conditions, and they are indeed small or some measure.
DR. FORD: I think maybe the question
yesterday was asked in the context or at least a
question was asked yesterday in the context of you
extrapolating out, and do you have any data to bound
that extrapolation, and that was in relation to the
corrosion, and not the flow induced vibration.
CHAIRMAN WALLIS: Well, I meant flow
induced in terms of vibration.
DR. FORD: Okay. But it was mentioned in
relation to the flow assisted corrosion that this was
a fairly low flow rate plant in comparison to the rest
of the fleet.
So are there other reactors, and not Duane
Arnold, out there which you have used in your
evaluation to answer this question that Dr. Wallis
asked? Is there data out there that would bound these
flow rate conditions, or vibration conditions, in
other plants?
MR. WU: In other plants such as -- well,
Monticello and Hatch?
DR. FORD: Or whatever.
MR. WU: Yes, whatever, and GE has generic
testing of up to 13 percent, or all the way up to 13
percent. So they are bounded by those.
DR. FORD: No, I think the question is are
there data in other operating plants operating -- and
it would be at these same flow rate conditions --
which have been operating successfully. I mean, that
is the question that is asked.
MR. WU: That is the question which --
that is the data that we tried to get before, and for
some reason we did not get it, because --
CHAIRMAN WALLIS: My question was somewhat
different. I thought that these things were tested in
separate effects tests. You test one separator and
one dryer, and you can run that up way above what you
get in the plant just to reassure yourself that you
are extrapolating or interpolating.
But that would be nice to see and would be
convincing, and it wouldn't just be -- and if you
could show that everything is scaled, then that is
fine, too.
But just to sort of extrapolate out there
on the basis of a theory without any data to hang it
on sounds a little bit dangerous.
MR. WU: I think they used to calculate
that with the extrapolation of system data, and --
CHAIRMAN WALLIS: Maybe this could be
answered before the full committee meeting or
something. I am not sure we are getting an answer.
MR. SHUAIBI: This is Mohammed Shuaibi
from the staff. If we can take that question back,
maybe we can come back at the full committee and
address it.
CHAIRMAN WALLIS: Maybe it would help if
there were a written reply to the subcommittee before
the full committee meeting so that we didn't have to
go through trying to extracting the answer orally, and
we could say, yes, we have read it and we think it is
okay or not.
MR. SHUAIBI: We could certainly do that.
DR. FORD: The specific question is that
given the fact that there have been flow induced
vibration induced problems in dryers in the past are
there any data, either in the laboratory or in full
scale, or in the operating plant, which justifies that
there will be no problem, and specifically at Duane
Arnold.
CHAIRMAN WALLIS: That seems a simple
question to answer.
MR. SHUAIBI: Justifies that there are no
problems at Duane Arnold?
DR. FORD: Yes.
MR. SHUAIBI: We will take that back.
MS. MOZAFARI: That justifies the
assumption of no problems at Duane Arnold.
DR. FORD: Because saying you are adhering
to the codes when there have been failures doesn't say
too much about the code.
MR. SHUAIBI: We will take that back and
we will provide an answer.
MS. MOZAFARI: Okay.
DR. POWERS: Let me ask a question on a
different answer, but that is still related to
materials and fatigue. The licensee has adjusted his
methodology for looking at cumulative usage factors
and in most cases saw a substantial drop in cumulative
usage factors for fatigue.
In one case, however, he reports a fairly
substantial increase in the cumulative usage factor,
and in particular I believe for the feed water
nozzles, I believe he shows a cumulative usage factors
coming up very close to one.
Did the staff examine the methodology, and
in particular did they look at the feed water nozzle
issue?
MR. WU: The methodology that GE used is
with respect to Appendix I in the ELTR-1. They said
they followed Appendix I of ELTR-1, which we had
approved before.
And the methodology says to compare the
inputs parameters, and the EPU parameters, and to
identify the inputs, and they don't have to do
anything. And if it is not -- they have to do -- to
get a scaling factor, conservatively based on whatever
is -- well, the pressure temperature difference, and
to come up with some scaling factor.
So they multiply the scaling factor and
multiply by the existing stress and that ends up to be
the -- and so the methodology that we approve, there
are no problems. So because this is a scaling factor
multiplied by the stress, the existing stress, the
stress factor they use is really conservative.
So anything below 1.0 -- and as a matter
of fact, we know that the stress is not limited to the
-- it is the total stress, also including the others.
DR. POWERS: You are going an awful long
way around the barn to answer what is a fairly simple
question. What I want to know is did you look at the
methodology, and I think the answer is yes.
MR. WU: Yes.
DR. POWERS: And how the question is did
you look specifically at what they had done for the
feed water nozzles, and do you concur that the
cumulative usage factor is less than one for that feed
water nozzle.
MR. WU: Well, we did look at the details
and their methodology.
DR. POWERS: That's all I needed to know.
MR. WU: Also, we looked at the details of
some of the usage factors. I mean, there are lots.
It is from .9 something way out to .199. And it goes
down. So how come it goes down that much, and the
answer we got is that in the past they used the worst
condition, based on the worst condition.
And the worst condition is the loss of the
feed water, and that is the worst, and from there they
got -- let's say it is one, for instance, and from
that they got the allowable cycle. And then they used
the allowable cycle, which is normally small, and used
or ate up all the cycles and that is too conservative.
So now they come back to do or to take for
each one, and for each one it is a different transient
for each transient, and maybe for 2 or 3, and after
the three, they use that number three for the rest.
DR. POWERS: Well, it's just that I find
it remarkable that everything drops down, and for
understandable reasons. And here is one case where it
goes up, and it seems logical that it should be a
substantial fatigue for the feed water nozzle.
And it gets close to one and you don't
check to see if you agree. I mean, it is within four
percent of one. I can't or I myself cannot calculate
cumulative usage factors up to four percent, but maybe
other people can.
MR. WU: As I said with the feed water,
the methodologies, we approved the methodology. So
they used the methodologies, and we did review their
detailed calculations.
MR. BROWNING: This is Tony Browning from
Duane Arnold. The staff did request a number of
summaries of the calculations in this area, and they
were provided to the staff.
And while it wasn't the full set of the
calculations, it was a fairly detailed summary of the
calculations that the staff did review. And
particularly one of the sets which was requested in
the last RAI were the cases where we were showing
ratios in the .98 and .99 range. So we did provide a
summary of those calculations to the staff.
MR. SHUAIBI: Dr. Powers, Mohammed Shuaibi
again. Would you like us to come back at the full
committee and address that issue as well?
DR. POWERS: I think what I am going to be
asking you to do when you come for the full committee
is to go through a little more discussion of the
strategy for the review.
I think you may be a victim of trying to
do this expeditiously, in which we posed a set of
questions here, and you are responding to this
specific set of questions, and really what we should
have asked you for was the strategy for the review.
But in the course of doing that,
understanding better where you are taking a
methodology and asserting, yes, indeed we have
approved this methodology in the case.
And then the specific thing of how much
detail you go into in looking at how they apply it,
might be a useful illustration for people. And this
would not be a bad example, simply because it is such
a striking example.
I think we can progress on to the next
topic.
DR. FORD: Are we going to be talking
about flow induced corrosion and stress corrosion?
MS. MOZAFARI: Right.
MR. CARPENTER: Good morning. My name is
Gene Carpenter from the materials engineering branch,
and I don't have any slides or overheads to give out
today.
Basically, the staff had talked to the
ACRS about the extended power uprate and how we did
the reviews for boiling water reactors at a previous
meeting, and to reiterate some of that information,
the BWR VIP, the BWR vessel internals project, had
provided a variety of reports for inspections and flow
evaluations of the safety significant flow of BWR
internals.
And those include the core spray systems,
the core plate top guide, standby liquid control, the
shroud supports, the BWR jet pumps, the LEPC system,
the lower plenum components, the vessel interior
diameter attachment welds, various instrument
penetrations, and the reactor vessel itself.
We have reviewed each and every one of
those inspection or flow evaluation guidelines, and we
have approved them. And basically those allow us to
have some assurance that the BWR licensees -- for
instance, this licensee -- will be doing adequate
levels of inspections to ensure that there are no
degradations that will occur before they will be able
to see them. There are no significant degradations.
Does that answer your question?
DR. FORD: Well, I have another specific
item. All of the VIP reports related to stress
corrosion cracking, both the disposition and result,
and inspection period and methods, were based on data
which was obtained in general with very, very low flow
rates.
So even below that which are currently
used in non-power uprated plants. What would be the
rationale for saying that they should be necessarily
applicable to power uprated plants operating at a much
higher flow rates?
When you are doing this evaluation and
applying the VIP documents, what went through the
examination process in your mind to say that, yes,
those VIP documents are applicable to these different
environmental conditions?
MR. CARPENTER: Well, again, as you
mentioned here, dealing with the various flow regimes,
and that is what John was just talking about, with
flow induced vibrations and he will come back to you
and talk about that to some greater extent. So I will
leave that to his further response.
We are obviously looking at the
chemistries, and as you may remember from your
previous life prior to the ACRS, BWRs have some fairly
stringent chemistry controls in place, and even more
so today than they did even 10 years ago.
We were also looking at the overall events
from a systems point of view. We also look to some
extent from the risk management point of view, and
those are aspects that I will leave aside to others to
talk about specifically, because I am not a PRA
expert, per se.
But to attempt to answer your question the
regimes that we have looked at, yes, they were not
specifically to the power uprated regimes. But we do
expect the licensees, when they do these power
uprates, to take a look at the extended flow regimes
and see if their applicables, or their usage of the
VIP reports are going to be maintained so that they
will stay applicable.
CHAIRMAN WALLIS: Are you speaking about
vessel internals here?
MR. CARPENTER: Yes.
CHAIRMAN WALLIS: And isn't the flow rate
the same though with the uprate as it was before? The
places where you worry about increased flow are places
like the dryers and separators, and places where the
flow really has increased.
MR. CARPENTER: Right, which is outside
the safety components that we are looking at. So the
basic internal components themselves as I had just
mentioned, they pretty much --
CHAIRMAN WALLIS: I thought my colleague's
question was why do you assume that what you did in
the past is applicable to the future, might be
answered by saying that there is no change in core
flow, and so what happens inside the vessel is more or
less the same as what happened before.
DR. FORD: Thank you for being my straight
man. I guess I was questioning -- well, there are two
things that are changing in the power uprate
conditions. The flow rates and/or the flux.
CHAIRMAN WALLIS: That's why distribution
is changing isn't it?
DR. FORD: Well, the flow rates, and/or
flux patterns, oth in concert or separately, and in
effect the cracking susceptibility.
The flux to a certain extent is taking
current or in some of the later VIP documents, but not
the flow rate. And so really my question is, is there
anything that makes you feel good or bad about
accepting these VIP documents which don't relate to
the higher flow rates to this particular condition?
I have an opinion, but since I have a
conflict of interest, I can't express it, and so I
guess I --
CHAIRMAN WALLIS: Well, the question
really isn't what makes him feel good or bad, but what
would make us feel better.
DR. FORD: Am I allowed to express my
personal opinion?
MR. BOEHNERT: I think you probably ought
to refrain from that.
DR. POWERS: I agree. You are entirely
welcome to ask questions, and if it leads us to an
equivalent opinion, then that's fine. But I don't
think you should guide us very much.
DR. FORD: Okay. I am now hamstrung.
MR. CARPENTER: To rephrase your question
then --
DR. FORD: There are two things that have
changed in Duane Arnold as they go into the power
uprate; flux patterns, and/or flow rate. Both can
individually and/or in conjunction affect cracking
susceptibilities for most of the reactor components.
The VIP documents upon which yesterday and
today we are seeing are saying that we don't have a
problem with regard to stress corrosion and cracking.
Those VIP documents did not take into
account changes in flow rate, per se. In fact, most
of the data upon which those documents were obtained,
the disposition curves, are extremely low flow rates.
And they don't take into account to any
great degree changes in flux on the cracking
susceptibility. So what makes you feel comfortable
about accepting their requests for this reactor, which
is operating in different conditions and which are
pertinent to the VIP documents?
MR. CARPENTER: Well, I don't think I said
that there is no problem here. If I did, I mis-spoke.
What the BWR VIP documents give us is some assurance
that there will be adequate inspections to determine
if there is cracking before it will progress to a
point that will be of concern to the staff, and
obviously to the licensee.
The BWR VIP documents that have been
reviewed and approved by the staff do specify a flux
regime, that being less than 8 to the 21 fluence
levels. Anything above that is considered a high
fluence regime and we don't necessarily agree with the
VIP at that point.
We are still in negotiations with with
regard to BWR VIP regarding what if anything -- what
additional inspections, if anything, should be
performed by the licensees.
As far as the flow rates, as Dr. Wallis
said, and as we agreed earlier, we will be coming back
tomorrow or at a later point to talk further about
that from a mechanical flow induced vibration point of
view. Does that answer your question?
DR. FORD: The applicant took benefit if
you like from the fact that they are using Noble Chem.
How does that come into your evaluation?
MR. CARPENTER: Noble Chem the staff
considers to be, when used adequately, a definite
benefit to the water chemistries. Obviously, it adds
in the hydrogen and to make use of it, and that
reduces the crack growth rate by a significant amount.
Basically, we have given an order of
magnitude reduction in crack growth rates for plants
making use of that. So that is overall a very good
thing from our point of view.
DR. FORD: Okay.
MR. CARPENTER: Any other questions?
Well, specifically related to the internals.
CHAIRMAN WALLIS: Well, I am a little
concerned that may be left with an uneasy feeling, and
I am not quite sure how it is going to go away.
MR. CARPENTER: Which uneasy feeling is
that, sir?
CHAIRMAN WALLIS: Just the whole way in
which there have been responses to questions in the
last hour or so.
DR. POWERS: Well, specifically with
respect to the inspection frequency, do we have any
problems with that?
CHAIRMAN WALLIS: Well, it is an
extrapolation of past experience isn't it?
DR. POWERS: I am sitting here wondering
how can I design an inspection frequency that is not
an extrapolation of past experience?
CHAIRMAN WALLIS: Well, when you are
uncertain and you presume, then you inspect more.
DR. FORD: Am I allowed to give an
opinion? Having put this bomb on the table --
CHAIRMAN WALLIS: Well, you can ask
questions and hoping that your opinion will appear
from someone else.
DR. POWERS: Okay. On this note, I am
wondering if it wouldn't be appropriate at this point
to take a break for about -- until 10:30.
CHAIRMAN WALLIS: Okay.
DR. POWERS: We will resume at 10:30
(Whereupon, at 10:17 a.m. the meeting was
recessed and resumed at 10:33 a.m.)
DR. POWERS: Back on the record. I think
we have progressed somewhat out of order. Can we get
back into the order?
MS. MOZAFARI: What we want to do is just
finish up on the material degradation issues, and I
want to briefly give Gene here one more shot at
addressing your questions, and then we have some
discussion on stress corrosion cracking or flow
cracking, the chemistry area for Kris Parczewski, who
is going to provide that information. So why don't
you go ahead.
MR. CARPENTER: And again the question as
we left before the break was what precisely is the
staff's level of comfort regarding the BWR-VIP
documents and why it bounds the extended power uprate
that Duane Arnold is asking for.
And again basically we have reviewed these
documents to a great deal of level, and Duane Arnold
is not looking at an increased, or an appreciable
increase in flow in the area of concern.
So the crack growth rates in those areas
should not significantly increase. It should not
increase at all, especially that they are using Noble
Chem.
So the staff has a great deal of comfort
in this area. Does that more adequately address the
question that you had?
CHAIRMAN WALLIS: Yes, it does.
MR. CARPENTER: Any other questions? If
not, thank you.
MS. MOZAFARI: Okay. Chris, if you want
to go ahead and come on up.
MR. PARCZEWSKI: My name is Kris
Parczewski, and I am from the Materials and Chemical
Engineering Branch, and I was involved in evaluating
the degradation of materials due to erosion/corrosion.
As you can see on this slide, there are
several parameters which are or which would affect
erosion/corrosion, or accelerated corrosion as it is
now called.
Two of them, velocity, which is at the
bottom here, which affects turbulence, and
temperature, are going to be affected by power
uprates.
The licensee evaluated this change, and
came to the conclusion in general that the effect is
very, very minimal. The highest effect would be on
the feed line, and on the main steam line, and those
changes are going to be taken care of by modifying the
core input in the code, so that it would predict the
rate at which erosion/corrosion takes place.
And the staff was satisfied that this will
probably take care of any effect of power outrate.
CHAIRMAN WALLIS: And by the code do you
mean the CHECWORKS code?
MR. PARCZEWSKI: This is the CHECWORKS
code developed by EPRI.
CHAIRMAN WALLIS: I thought there was a
very good presentation made yesterday on the fact that
they do a lot of examinations by their
erosion/corrosion program, and compared it against the
CHECWORKS predictions. Did you see those
correlations?
MR. PARCZEWSKI: The comparison?
CHAIRMAN WALLIS: Yes.
MR. PARCZEWSKI: I looked at them briefly.
CHAIRMAN WALLIS: But you saw them?
MR. PARCZEWSKI: Yes.
CHAIRMAN WALLIS: And can you -- and it
was also mentioned that other plants have higher flow
rates than that which Duane Arnold are applying to go
through.
MR. PARCZEWSKI: Yes.
CHAIRMAN WALLIS: Have you seen data from
other plants which reassures that extrapolating the
CHECWORKS code is valid?
MR. PARCZEWSKI: No, I did not see that
data. However, CHECWORKS was verified against several
data, and so I trust the code would probably give you
a proper prediction.
CHAIRMAN WALLIS: I don't doubt that, but
I think we all have a problem that when you are
starting to change -- and especially two variables,
temperature and fluoride, and you are going to
extrapolate them beyond your database, are you going
to necessarily going to have a good correlation?
MR. PARCZEWSKI: You see, the CHECWORKS
code was based on the data from several plants coming
from this country and from abroad. So it has a very
broad database it is based on, and it is being
continuously updated. There is a special effort in
EPRI which updates the data very often.
DR. FORD: But why a database that is
being used to qualify the code includes conditions of
temperature and flow rate that we are talking about
here?
MR. PARCZEWSKI: Yes, that's right. It is
bounded.
CHAIRMAN WALLIS: How much scatter is
there in the data? I mean, do you see a correlation
through this data?
MR. PARCZEWSKI: Excuse me?
CHAIRMAN WALLIS: Is there a lot of
scatter in the data around this correlation?
MR. PARCZEWSKI: There is quite a lot of
scatter, yes.
CHAIRMAN WALLIS: Typically how much?
MR. PARCZEWSKI: I cannot tell you the
exact number, you know, but there is not one single
curve.
CHAIRMAN WALLIS: So you used some average
curve or upper bound, or what did you use?
MR. PARCZEWSKI: Usually there is a bound,
upper and lower bound, and obviously it has to be
within those bounds.
CHAIRMAN WALLIS: Do you mean the mean
curve as a predictive tool?
MR. PARCZEWSKI: I'm sorry?
CHAIRMAN WALLIS: I am trying to figure
out how you use -- you said that the data had to be
between the bounds, and I didn't understand that. I
mean, if you have bounds on the correlation, and when
you take it to the other point, it has to be within
the bounds?
MR. PARCZEWSKI: Well, it has to be below
the upper bounds.
CHAIRMAN WALLIS: And so what do you use
for licensing purposes? Do you use the upper bounds,
or the mean, or what?
MR. PARCZEWSKI: Well, upper bound
obviously. It has to be the upper bound.
CHAIRMAN WALLIS: But does CHECWORKS
predict the upper bound?
MR. PARCZEWSKI: I beg your pardon?
CHAIRMAN WALLIS: Does CHECWORKS predict
the upper bound or just the mean?
MR. PARCZEWSKI: The means.
CHAIRMAN WALLIS: So how do you figure the
upper bound into some licensing criteria?
MR. PARCZEWSKI: Well, it is -- I think
the code is based on the data, and usually it is --
definitely it predicts below or above the lower bound,
and obviously to be on the safe side.
DR. FORD: Assume that the CHECWORKS
prediction code looks like this, and you are saying
that you have data that is in the upper bounds of the
data, and the CHECKBOOKS, and that is the two
questions that we have been asking. Here is Duane
Arnold now, and --
CHAIRMAN WALLIS: This is a freshmen
course in data correlation and interpretation.
DR. FORD: And here is Duane Arnold's
power uprate. Our questions have been is the Duane
Arnold power uprate -- are there other data points
which codify the CHECWORKS code, and the answer has
been yes.
The next question was when Duane Arnold
goes to this flow rate, what are they going to base
their -- what do you approve their basis for their
inspection in their erosion/corrosion program? Is it
based on this value or this value?
MR. PARCZEWSKI: Well, you see, the data
-- one thing is that the code is being calibrated each
time, and so all the data from measurement are being
included in the code. So it averages all the data
which are being used for the calibration of the code.
DR. FORD: So it is not an absolute line.
CHAIRMAN WALLIS: That doesn't answer the
question.
DR. FORD: The CHECWORKS is not an
absolute correlation, which I thought it was.
MR. PARCZEWSKI: No, it has to be
calibrated. Usually, you know, you take at least two
measurements, two sets of measurements, and you add up
to the code to calibrate so to speak.
And each time you take the measurement,
and you keep adding to the code, and so the code keeps
getting more and more precise for a given plant as you
yield more and more data.
CHAIRMAN WALLIS: Or it might be less
precise if the data doesn't fit any pattern.
MR. SEVERSON: My name is Russ Severson
with Duane Arnold, NMC. Let me try and add a couple
of things here to try and help clarify a little bit.
I think we are getting mixed up between flow rate and
what has happened, and what the actual corrosion that
has happened.
When you do apply CHECWORKS, and you do a
corrosion program, you have two things going on at
once. One is the model itself, and which is the EPRI
model, and we have industry and international testing
that went into the model at different parameters.
And you have your actual inspection data,
and what CHECWORKS does is that it allows you to
compare the two to see if your inspection data is
matching your model, and therefore you have a clear
understanding of what has previously happened to your
system, and what will happen.
Now, what will happen with what we have
performed here, and which Kris was trying to allude
to, we did a parametric study using the CHECWORKS
model to say, okay, we now believe we have modeled
these lines fairly well because we have good
predictions, and so therefore the code is working.
Now, within the code there is bounds of
with these temperature changes, and the flow rates
that we are seeing. So therefore with the code we can
predict what will happen in these lines.
And since we prior could predict with this
code, then we have very high confidence that we can
predict in the future. Now, the temperature change
really -- and as we showed you before, it is based on
the solubility of the iron, and the temperature change
really affects it, and you run the whole gambit of
that line in feed water in these systems.
So all you really do is you change the
location of where that happens, and so now we are
having it happen a little bit forward in the feed
water or in connate than we had before, would be your
300 degree mark.
Whereas, the 300 degree mark would have
been a different line prior to power uprate, and you
see those effects.
CHAIRMAN WALLIS: The other question if
you are going to use this figure on the board here is
if you are doing inspections, and you are measuring
corrosion rate, where did it actually fall in Duane
Arnold, because this global correlation of data
doesn't reflect the particular chemistry of a
particular plant.
MR. SEVERSON: Well, I believe I
understand your question. We don't -- go ahead.
CHAIRMAN WALLIS: If you put some
measurements on that code for Duane Arnold
measurements where would they be? I think we are
saying that we can envision a logical process for
decision making, but we don't quite understand what
yours is.
We don't quite understand why the staff
approved it, and that's all, and we can't follow the
logic.
DR. POWERS: I think you have adequately
expressed the challenge that we are facing here.
Quite frankly, it looks to me like in many of our
cases there is an approved methodology that the staff
has accepted in the past.
And the question we are asking is how much
investigation does the staff do for the application of
this methodology for this particular application, and
how did they do it? And we are having challenges
understanding that.
MS. MOZAFARI: So we will just take that
under advisement. We will try to provide a basis.
CHAIRMAN WALLIS: I think it is more of a
generic problem.
MS. MOZAFARI: Right.
DR. POWERS: It is very much a generic
problem.
MS. MOZAFARI: Okay.
CHAIRMAN WALLIS: This is a generic
problem.
DR. FORD: We are all scientists and we
are interested in the details.
MS. MOZAFARI: Right.
DR. FORD: And therefore we are asking you
how did you go through the analysis of these? I don't
doubt that it is a good process. We are just
interested in how did you do it and we are not
understanding.
MR. PARCZEWSKI: Basically, we just
verified the information provided to us, and our
knowledge of the code, and that is probably a
satisfactory way to predict the rate at which
corrosion takes place.
MR. SEVERSON: Kris, I have one more
thing. This is Russ Severson again. I guess the
point that I was trying to make was that I believe
that we have validated and we have verified CHECWORKS
works.
We know how to employ it at Duane Arnold,
and we have inspections for it, and we know how to use
the model to predict these new flow rates. And the
fact that oxygen is just as important as flow.
There are many factors here that are just
as important, and this is just one of them, and I
believe that at Duane Arnold that we know what
CHECWORKS is predicting, and we know what our wear
rates are. And we have benchmarked the code.
MR. PARCZEWSKI: Basically the problem is
that it doesn't involve only using predictive code,
but relies on the actual measurement which is being
done on the component that is most susceptible to
erosion/corrosion. So there is outward verification.
DR. KRESS: How do you use this CHECWORKS
prediction and in combination with the inspection
findings to either say your inspection interval is
okay, or to adjust it?
Are there criteria used to change your
inspection interval or keep it? How is your
inspection interval decided in the first place?
MR. SEVERSON: The inspection interval is
every outage. We can't get at these pipes without
being in an outage because it is hot.
DR. KRESS: That's a pretty good criteria.
MR. SEVERSON: So what we do after an
outage, and after our inspections, we pull these
inspections, and we run the CHECWORKS code, and we
predict what the wear rates will be by the next
outage.
We decide where we want to inspect to
further refine the model, and to further refine and
show that our model is accurate, and what inspections
we want to do for other reasons, and those are what we
inspect, and we do that every outage.
DR. KRESS: And the CHECWORKS helps guide
where to focus your inspections?
MR. SEVERSON: Well, yes. It gives us the
feeling of what the wear is in the lines so that we
can take whatever action that we need to do, that we
believe that we need to do at that time.
CHAIRMAN WALLIS: And the measurements
that you make when you do these inspections, do they
agree with what you expected from CHECWORKS?
MR. SEVERSON: Yes, within what the model
bounds are.
CHAIRMAN WALLIS: But that is not my
question. We don't know how uncertain the model is.
If we are going to go with something like the picture
on the board, I would like to see some red dots or
something which says this is where we actually are
when we do our inspections, and this verifies that we
are close to some mean line or upper bound, or
whatever it is.
MR. SEVERSON: Well, I tried to push the
important parts here. First, as I was saying before,
in or flow water we have 130 or 140 mils of margin.
I am attempting to closely lock in wear rates of
between 3 and 4 mils per year. I believe that we have
an excellent program to know when we are going to have
problems.
CHAIRMAN WALLIS: Well, this is the
problem that we have with lots of SERs, and we have an
issue raised, and they say read the text, and it says
we talked with the applicant, and the applicant
assured us that CHECWORKS was used in some way, and
this is a standard method.
And then it says that the staff finds the
response acceptable. We get this all the time, and
then when we start digging into it, we get into this
kind of a situation, and we have got to do something
about that.
There has got to be a better rationale for
the acceptability I think that the staff presents to
us. I mean, we can pick on any one of these, and if
we just pick on a few and we get this kind of
vagueness, then it doesn't reassure us too much.
DR. POWERS: I want to move on to another
issue at this point. I think we have explored this
one to the limit of our time availability now. I
propose that we go to the PRA analyses and then the
open issues.
MS. MOZAFARI: There is just one thing
that I would like to say, and I probably should have
said it up front. The staff's review approach -- and
I think this is what you are trying to get at -- was
how did they approach the reviews.
They pretty much looked at the ELTR-1 and
2, and tried to give it the framework of what has been
accepted in the past, and was it founded in some way
by what is generically out there.
They looked at the Monticello safety
evaluation, and that provided an indication of how
deep to go into the review, and were there significant
differences at Duane Arnold than there were at
Monticello.
And then if there were plant specific
design differences -- and this addresses most all of
the systems -- they tried to address it in the safety
evaluation. If there were not plant specific
differences, if there was not something very unusual
about the way Duane Arnold was addressed, then it may
not have been brought out as something very specific
and different.
So it would have followed the general
approach at ELTR-1 and 2. And then the staff made
several additional requests for information to
corroborate what was in the supplement and what was in
the original submittal.
And when we needed more information or we
needed to be sure, you know, from our point of view to
develop confidence in the staff, it is all documented.
DR. POWERS: The problem is that they are
not documented. That when we look at the SER we get
these vague assurances that the problem was resolved,
and we don't understand why.
When we discuss it with you, it is not
evident that you even understand the methodology, let
alone how it was resolved. I would like to move on.
MS. MOZAFARI: Okay.
MR. HARRISON: My name is Donnie Harrison,
and I am with the PRA Branch in NRR, and I am going to
try not to repeat everything that was said yesterday
by the licensee.
I don't think you are going to see a whole
lot of information that is different from my
presentation than what Brad Hopkins gave yesterday.
The Duane Arnold submittal, as Brenda just indicated,
followed the ELTR-1, and they provided risk
information per that.
The staff reviewed internal events,
external events, shutdown operations, and the PRA
quality. Under internal events, I just broke out that
there is four main areas that we look at; initiating
event frequencies, component reliability, success
criteria; and operator actions.
Again, most of those topics were covered
yesterday, and so I am just going to provide what the
summary results are, and if you want to go into more
detail, we can.
CHAIRMAN WALLIS: How do you assess PRA
quality?
MR. HARRISON: It becomes a number of
different factors that are involved. Basically, you
are asking a question of does the plant models used in
the PRA represent the plant that is operating, and in
this case the plant that is going to be operating at
extended power uprate.
And so I want to caveat that first with
how that information is being used. In this
application, it is only being used to confirm that
there is no new vulnerabilities being created, or we
are not on a cliff edge with our risk, and with this
uprate, we will fall off the cliff.
It is more of a confirmatory analysis, and
it is not done as a licensing analysis. With that in
mind, we looked to see if there has been a peer
certification done. We will look and see if there
were any findings in the IPE and the IPEEE on the
application's PRA in the past.
We will ask questions if we see that there
is areas that are changing in the plant to see how
those are modeled in the revised PRA, and so we will
just confirm that the model does represent the as
built or is going to be operated plant.
So you stole my thunder from my last
slide. The first three topics under internal events,
initiating event frequencies. The licensee indicated
that they did not anticipate any changes in
frequencies of events.
I will note that there are changes
occurring, and modifications occurring to main
transformers, and the key electrical breakers, to make
sure that there are operational margin.
The staff considers that as long as the
equipment is operating within its margin, and within
its operating limits, that we don't expect the
frequencies to change.
DR. POWERS: What is the frequency
dominant accident during normal operation?
MR. HARRISON: I believe it is the loss of
all site power event, and ATWS -- and I confirmed that
before here, and ATWS is second on that list, I
believe.
DR. POWERS: Can the staff ensure that the
increase in power is not going to affect grid
stability?
MR. HARRISON: The grid stability question
is typically answered through the electrical branch.
DR. POWERS: But they surely must have
something packed in the PRA?
MR. TREHAN: This is Nedra Trehan,
Electrical Engineering Branch. We do look at
stability, not in detail, but that stability should
be maintained -- with the largest unit on the grid, of
the nuclear power plant unit, or the most critical
transmission line.
And we see that those frequencies are
within acceptable limits, and we do look at stability,
the general capability curves, whether they are within
the range, or lighting power factor range that they
are being operated. Thank you.
DR. POWERS: And once they have done that
assessment, how do you translate that into a change or
no change in the frequency of station blackout?
MR. HARRISON: Well, what we do is we look
at that as being a no change then in the frequency of
--
DR. POWERS: No matter what it comes --
MR. HARRISON: As long as it is acceptable
and it is within its margin, and within its operating
limits, we at this point assume that the frequency
will not change.
However, there are tracking means, and if
plant specific data starts to show an increase, then
that would be reflected in future updates of the PRA
model.
And that same logic applies to component
reliability. We don't expect any changes in failure
rates, and there are monitoring programs, and
maintenance rules, and other types programs, that are
used to either maintain or to track the failure rates.
And at this time we don't see a change
there. If one were to start to change in the future,
it would be reflected in a future update of the PRA.
MR. TREHAN: This is Nedra Trehan.
Regarding your question about the frequency. What we
are doing with the power uprate is increasing the
kilowatts, which is calculated into your frequency.
If you are increasing the power kilowatt, your
frequency is in better shape.
On the other hand, because KVA or MVA of
-- if you are increasing the megawatts at the expense
of -- for that we have to change that station's given
power reactor, or install capacitor banks to take care
of the large shortage created by a power uprate.
MR. HARRISON: Okay. As well, on success
criteria, we don't expect any change. The licensee
reran their -- some map runs to confirm that their
success criteria as to the power uprate level had not
changed, and that was the results of that analysis.
The one area that we did see where there
were impacts were in operator response times. As
indicated yesterday, there were five operator actions
that were identified as potentially having raw values
of greater than 1.06, which meant that they could have
a 10 to the minus 6 impact on CDF if they were assumed
to be filled.
And four of those dealt with ATWS and one
of them dealt with a high pressure transient event.
On the ATWS, we broke it down into those four events,
and they are SLC initiation, and the second one is
inhibiting ADS if you have high pressure injection
available.
The third one is initiation of lowering
the water level to control power; and the fourth one
as indicated yesterday was a combination of initiating
SLC level and lowering power level with turbine bypass
valves available.
On the first one, there was a question on
timing of the SLC initiation at four minutes, and at
that, I will pass that on to Dick Eckenrode to just
provide some information the human factors folks have.
MR. ECKENRODE: My name is Dick Eckenrode,
and we looked into all five of these events as far as
the timing was concerned, because in all cases that is
the key thing, is the time available has been reduced.
And the only one that was significant was
this one, and we compared all five of them to ANSI
Standard 58-9, which is a rather conservative standard
in operating timing.
The only one that came close was this.
This one, the ANSI standard actually said that it
would have taken about 9 minutes,a nd we should have
9 minutes. So they were already less than that with
a six.
And then it had gone to four, and we asked
a lot of questions of Duane Arnold, and got a lot of
good answers, one of which is that this particular
event is one of the critical tasks in the operator
requalification program.
And it is looked at in all of the
stimulator and a lot of the simulator runs. The one
that we had them go back and give us a count of the
number of times that they have run this.
And since 1997 through the present, it has
been run I think 58 times, with a 100 percent success
rate. We felt that this was significant to say that
they could do it in the time available.
One thing you have to understand is that
the time was not the critical item here, but
approaching the byte temperature is the critical
parameter. So they weren't really recording times.
They were simply looking at the comparison
of the temperatures, and when the temperature got
close to the byte line, they initiated SLC.
As far as the actual actions that have to
be taken, it was estimated by the licensee that it
really takes about 10 to 15 seconds to perform the
task. So we felt that they were well within the
capabilities.
MR. HARRISON: The net result of the
impacts of the operator actions on the overall CDF and
LERF for the internal events are shown here as
increases of 10 to the minus 6 approximately; and just
a little over 10 to the minus 7 for LERF.
DR. POWERS: These are reiterations of the
staff's analyses and the products of an independent
analysis?
MR. HARRISON: Right. We did not perform
any analysis to confirm the numbers. I will note also
on the upper actions that we did ask the license to go
back and just look to see if there were a number of
operator actions just below their criteria for
screening, which they did.
And they came back and only had one event
that was close, and even with it, it was the recovery
of river water supply, I believe, and that only had an
impact of -- if you assumed it filled, it was a seven.
And the licensee also went back and
doubled all their HEP values for things that were
screened out, and showed that the impact was just a
little over 10 to the minus 6. Both of those were
just used as kind of a sensitivity data to confirm
that we weren't missing anything.
And on the external events, Duane Arnold
has a seismic and fires were evaluated, and all other
external events were screened out.
CHAIRMAN WALLIS: Can we go back to that?
The doubling -- the use of doubling, is that something
that was proposed by the licensee, or something that
you proposed, or was it negotiated? Could it have
been a factor of something else?
MR. HARRISON: To be honest, I can't
remember if we asked them to double, or if they
provided -- I think they provided the doubling in
response to a question that we asked them about the
sensitivity of the results to things that had been
screened out. I think that is what happened.
And the staff accepted that just as a
sensitivity, and not as -- again, as a confirmation
that there was not a lot of actions that can pile up
together to get you there.
On external events, like I said, other
than seismic and fires, other external events were
screened out through the EPRI process. There is no
direct impacts of the power uprate on earthquakes and
fires.
And their analysis just shows a path
through the upper actions that were shown to be
important, and the internal events pass through these
external events as well.
They did not identify any vulnerabilities
that were created by the power uprate, and when you
increase the external events CDF by that, you get an
increase of 2 to the minus 8, for an overall external
event probability of 3.7 to the minus 6.
And I believe that is all fire if I am
correct, because they do a seismic margins analysis.
So on the seismic area, it is just to ensure that
there is no vulnerabilities created as part of the
uprate.
DR. POWERS: Power ampage and more current
flow, does it change the risk of a switch gear fire?
MR. HARRISON: That would be a component
failure question again, and I think you would be
dealing with what is the probability of having an
event like that.
And I don't think you would be able to get
a good number one way or the other on what that would
be as a result. I think conceptually that you are
right. You could increase the fire.
DR. POWERS: I honestly don't know. I
mean, all I know is that we have the IPEEE insights
report that tells us which --
MR. HARRISON: And I do know that they did
a fire analysis at Duane Arnold. I don't recall what
was the actual dominant failure modes that resulted in
the six value. I am not sure.
And if we move into shutdown operations,
I think as was indicated yesterday, there is an
increased decay heat during shutdown operations, and
so that is going to extend the time where you have two
pumps that have to be available, RHR decay heat
removal.
You are going to have reduced times to
boiling, and therefore you are going to have shorter
operator response times. However, for BWRs, typically
those times are in the matter of hours, and so you
typically won't impact your operator action human
error probabilities.
As well, Duane Arnold uses a shutdown risk
management process, NEMARC 91-06, and they monitor a
number of different capabilities and features through
that through an outage.
The staff looked at that and determined
that based on having a risk management approach, and
based on the fact that you have hours to boiling
typically, that that was an acceptable risk management
approach and would be acceptable for a power uprate.
DR. POWERS: Yesterday in our discussion
of the analysis of human error probabilities,
primarily connected with normal operations, and not
the shutdown operations, the speaker acknowledged that
he did not have expertise in that area, but said that
they had looked at those probabilities in a variety of
ways, and he thought that included fires.
Did you look specifically at how they
calculated the human error probabilities?
MR. HARRISON: No, we did not. If you
will note, the human error probabilities that they
were using -- for example, the four minute time window
for ATWS and SLC initiation, in my view was a
conservative number.
It is almost 20 percent of the time that
they are saying that their operators are going to
fail. They have got data that supports that they make
it all the time. So in looking at that, I see their
analysis as being conservative, and their numbers tend
to be that way.
Their human error probabilities that we
did look at, you weren't down in the 10 to the minus
4 for operator actions in 15 minutes. You were
looking at high 10 to the minus 2s. And those seem
reasonable.
So we didn't look at specific methods, but
we looked at the reasonableness of the numbers that
they were producing. And just to touch on PRA
quality. Again, the question is how it is being used
in this decision making process, and the risk
information is being used to provide confirmatory
information, and it is not being used to make the
ultimate decision.
It is just a support tool. The staff
looked at the IPE and the IPEEE and safety evaluations
that were performed, and they did not identify any
major weaknesses in the Duane Arnold IPEs.
Duane Arnold uses their PRA as part of
assessing hardware changes. So it is used as part of
the plant configuration operating process. And then
the final thing that we also considered was the fact
that it was through a BWR Owners' Group peer
certification process 3 or 4 years ago or so.
And those factors we considered in
determining that we thought that the Duane Arnold PRA
was acceptable for its use in this application.
And the last slide just provides a summary that walks
through each of those areas that we have just
discussed, and presents just a little bit of results.
Their change in CDF and change in LERF
values are in the small risk increase area for
internal events. They are in the very small risk
increase range for external events. Again, noting
that is fires.
And they have got a process for shutdown
operations and the staff found their PRA acceptable
for this application.
DR. POWERS: I have to say that I am much
happier with the statement under shutdown operations
that there is negligible risk, rather than what you
said on the first or the original slide, which says no
significant impact. There certainly is an impact.
MR. HARRISON: Right.
DR. POWERS: There may be no increase in
risk.
MR. HARRISON: Right. There is an
operational impact.
DR. POWERS: But there is a very definite
impact.
MR. HARRISON: That's true. I will change
my slide for next time. And that is the presentation
of the PRA. I would be glad to answer any questions.
DR. POWERS: I would ask this question,
and you may not be the right one to answer, but I'm
just curious. As soon as this power uprate gets
implemented the IPE for Duane Arnold is no longer
germane by in large. Does the staff then go about
changing the work sheets that the inspectors have for
the significance determination process?
MR. HARRISON: That is a question that I
hadn't even thought of. Do we have any thoughts?
DR. POWERS: You may not be the one to ask
that question.
MR. RUBIN: This Mark Rubin from the
staff. I can't give you a good answer as to the SDP
work sheets, but for the maintenance rule
implementation, certainly their assessment of
maintenance impacts for assessing the programs have to
rely on a PRA that is adequate to the task.
And during a maintenance rule follow-up
inspection, if they were not reflecting that, I think
they would not be in compliance with the rule
requirements.
DR. POWERS: One other question that comes
to mind in that vain is if you look at changes in the
CDF and changes on LERF, did you look at changes in
raw and risk reduction worth of components and
systems?
MR. HARRISON: Not directly, but just as
a note, that when the licensee performed their screen
of what components to look at, they used a raw value
for components and operator actions. So there is some
consideration of that in the process, but it is not
like you did a raw for including initiating events and
everything else.
DR. POWERS: Any other questions of the
PRA work that was done, recognizing again that this is
supportive and not the basis of the application? If
not, I think we can move on to the next subject.
MS. MOZAFARI: You did ask some questions
about -- you did want us to address grid stability,
and we do have some members from the electrical branch
here if you have some specific questions concerning
grid stability.
DR. POWERS: I thought we had gotten the
answer earlier.
MS. MOZAFARI: You are happy with that
DR. POWERS: Well, I got the answer.
MS. MOZAFARI: The answer may not have
been sufficient for what you wanted, but --
DR. POWERS: Well, I understand what you
did.
MS. MOZAFARI: Okay. Then we will just
move on. There were open issues that were indicated
in the draft safety evaluation. One of them had to do
with the start up testing, and the start up testing
issue, Mohammed Shuaibi has been following it pretty
closely.
The staff has not come to closure on that
yet, but it doesn't -- it is not an issue at Duane
Arnold at this point, and it will be handled in a
license condition when they get to the point where
they would trigger the requirement to do start up
testing.
And by that time we would have made a
decision on the start up testing with our staff. It
doesn't become an issue for Duane Arnold at this
point. So this will remain an issue that will be
addressed when Duane Arnold gets to the power level
start up testing where needed.
And then the other issue had to do with
MPSH, and Kerry Kavanaugh is going to -- we have a one
page handout for that to pass around.
MS. KAVANAUGH: I am Kerry Kavanaugh of
the staff. As you heard yesterday, it is the
licensee's position that their licensing basis for the
use of containment overpressure is based on margin,
which is 2.7 psig.
And they also stated that when they were
originally licensed that they were licensed with
credit for containment overpressure. The staff agrees
that they were licensed for use of containment
overpressure from their original licensing basis.
However, the staff does not agree that
their licensing basis is based on margin. The staff
believes that their licensing basis is based on the
magnitude of the overpressure required and the
duration of that overpressure as it is required.
This was reflected in their original
response to the staff questions on their MPSH when
they were licensed. It was in -- their response was
a graph that presented the containment pressure versus
the time, which represented where the pressure was in
the containment over the accident analysis, along with
the MPSH requirements during that same time period.
This graph was in the Duane Arnold FSAR
and updated FSAR, up until 2000 when it was changed,
the figure was changed. During the years, we believe
that that graph was the basis for their licensing
basis.
When we got to this issue, we had quite a
few discussions on it. The staff has reviewed in some
respects their MPSH calculations, and we agree with
their MPSH analysis for the extended power uprate.
We have sent them a letter, dated
September 25th, that basically tells them that any
change that increases the magnitude or the duration of
the required overpressure than what they are using for
their extended power uprate would trigger 10 CFR 50.59
criteria, and would require staff review and approval.
That will close the open issue.
DR. POWERS: I guess I understand the
approach. Are you telling me that this is an issue
that will be resolved if I just wait long enough?
MS. KAVANAUGH: Well, unfortunately, we
couldn't resolve it. So they removed that figure from
the graph that we were using as their licensing basis.
It is now a containment pressure versus suppression
pool temperature, which shows that as the pool
temperature goes up that they will require containment
overpressure.
It doesn't tell you how long they are
going to need it, nor does it tell you how much per
se, because you really don't know how long they are
going to be there.
When we discussed containment
overpressures issues with the ACRS staff 3 or 4 years
ago, we gave you our approach to resolving the
increasing number of licensees that were coming in
needing it, and it was based on this time and
duration, and an understanding of how much they
needed.
And we have not had problems with Duane
Arnold in the past because we had this information on
the docket. We don't have that now.
CHAIRMAN WALLIS: What is the criteria for
acceptability for this time and duration? They
mentioned 2.7 psi required, and they showed us that
they had much more than that. They didn't say much
about time.
MS. KAVANAUGH: They didn't say anything
about time.
CHAIRMAN WALLIS: Is time the problem
then?
MS. KAVANAUGH: It is very plant specific
as to what the criteria is. We have a safety guide,
Safety Guide 1, that says that you should not be
granting any containment overpressure for your break
LOCA analysis.
However, there is a handful of plants with
specifically boilers that cannot meet this
requirement, and they were licensed not meeting the
safety guide originally and we were aware of this.
As time has gone on, there has been
changes with the plants, and most specifically with
the BWRs with the strainer issue, and all the BWRs
have replaced their ECCS strainers.
And that has changed their headlocks
calculations, which is has changed their reliance on
containment overpressure, along with other
modifications to the plant.
When plants come in needing credit for
overpressure, the approach that we have used is that
we give them what they need, because we haven't found
any licensees willing to change their pumps out of
their plants.
So our only opportunity is to evaluate
their license, approve their analysis, but give them
what they need and allow some room such that they can
have some flexibility for operational changes.
Some plants need higher amounts of
overpressure and some don't. For Duane Arnold,
because they are going up to 209 degrees, I believe is
your peak pool temperature, they are going to need
approximately 5.8 psig, and I don't remember for what
the time period was, versus two before the EPU.
If you look at another plant with higher
pump requirements, they would be needing a higher
amount for a lot longer amount of time.
CHAIRMAN WALLIS: Well, I don't quite
understand your philosophy of giving them what they
need. How is this related to public safety?
MS. KAVANAUGH: Well, since we know what
their analysis is, and we are looking at the risk
associated and the frequency of having a large break
LOCA, we know what their analysis is.
And the analysis for the containment
analysis is generally very conservative. They use the
super HEX code. They use the ANS 5.1 decay heat,
along with a two sigma margin.
Their analysis is done for worst case. So
it is generally a very conservative analysis. There
really isn't any other way to -- besides changing out
the pumps, which would be very expensive for them, to
have them meet this safety guide. I mean, the --
CHAIRMAN WALLIS: Well, should I feel good
about that? It looks as if you -- that when they need
something, you give it to them, but I don't understand
the criteria for ever turning them down.
MS. KAVANAUGH: Well, I don't believe
there has been a criteria for turning them down.
CHAIRMAN WALLIS: Well, you might as well
just say we have got a rubber stamp here.
MS. KAVANAUGH: What we do is with a lot
of care and consideration. I understand your concern,
and it has been a hard spot for all of us, but --
CHAIRMAN WALLIS: Is this another case
where the rationale is fuzzy?
MR. SHUAIBI: This is Mohammed Shuaibi
again. We do go back and look at what is available.
It's not that we will give them whatever they want.
We will go back and look at what is available and make
sure that it is available.
We will look at their containment pressure
calculations as we did in this case. So there is
margin there. It is not that we will give them what
they want, and given a situation where their pumps
aren't going to be able to perform.
MS. KAVANAUGH: I mean, the key assumption
is that the containment pressure will be there as long
as you don't lose that containment pressure. The
concern is if that containment pressure isn't there.
CHAIRMAN WALLIS: Well, isn't there then
perhaps a power uprate level where you would stop
giving them what they need? If they wanted a 25
percent power uprate, and then this would give you a
suppression pool temperature of 215 or something -- I
mean, there must be some point where you say you can't
have what you need.
MS. KAVANAUGH: Well, we haven't reached
that evidently yet.
CHAIRMAN WALLIS: Apparently not. How do
you know when you reach it?
DR. KRESS: And where do you decide it
will be?
MS. KAVANAUGH: No, there is no definition
as to where it would be.
CHAIRMAN WALLIS: So there is no speed
limit?
MS. KAVANAUGH: But our only control is
reviewing the analysis and then getting staff
approval. That is our only mechanism for control.
MS. MOZAFARI: Mohammed, do you want to
address that?
MR. SHUAIBI: I think clearly that there
is a speed limit. I think what your containment is
able to withstand is a speed limit, although that is
the extreme.
CHAIRMAN WALLIS: There is no speed limit
for MPSH per se then?
MR. RUBIN: This is Mark Rubin again, and
I will just jump in because I think Mr. Hannon has
already left this meeting. Clearly, I would only
point out that the safety guide is a not a regulatory
requirement.
It is a review guideline, and a very old
one additionally. I think perhaps what we are being
told is that the staff's evaluation of the plant
specific containment analysis is showing that the
actual pressure that a good analysis shows is well lin
excess of the extra delta-P that they need for the
MPSH requirements.
And the staff has confidence that the ECCS
systems will successfully operate because of that
analytical result, and that public safety is ensured
because of that.
DR. POWERS: How does that square with the
single failure requirements for the pumps.
MS. KAVANAUGH: I'm sorry?
DR. POWERS: How does that square with the
single failure criteria for the pumps?
MS. KAVANAUGH: Well, most plants are not
licensed to assume a failure of containment along with
a LOCA. I mean, that is beyond their design basis.
MR. RUBIN: If you mean a single failure,
or a single active component failure that would result
in increased head requirements, I'm sure that is in
the analysis.
MS. KAVANAUGH: Oh, yes, that is in the
analysis.
DR. POWERS: All right. But your answer
is the one that I was looking for.
MS. KAVANAUGH: Okay.
DR. POWERS: She got it right. She knew
what I was talking about, even if I didn't.
CHAIRMAN WALLIS: I guess I would be more
reassured if instead of what I heard was give them
what they need, if there were some kind of an
explanation like it affords here where you have got
some kind of prediction that they are making, and this
is what they need.
And then you can explain why it is
acceptable to be in the region in which they propose
to be based on some argument which is quantitative and
logical.
MS. KAVANAUGH: Well, I mean, I understand
your concern that they do do a containment analysis.
It is a minimum containment analysis.
And they use that as a basis to show now
much containment pressure they have available. They
don't use all that containment pressure.
CHAIRMAN WALLIS: Well, they believe that
the pumps will operate?
MS. KAVANAUGH: They believe that the
pumps will operate.
CHAIRMAN WALLIS: And what is your basis
for believing the pumps will operate?
MR. SHUAIBI: I think in this case -- and
this is Mohammed Shuaibi again -- that we did
confirmatory analysis in this case --
MS. KAVANAUGH: For the containment.
MR. SHUAIBI: -- confirmatory containment
analysis for this case, and we are comfortable with
their values on the pressure that is involved in
containment for the scenarios. Unfortunately, we
don't have the lead reviewer for that here, and that
is what we offered earlier, that he could comment to
the full committee and talk about those independent
analyses that we did.
DR. POWERS: From a historical point of
view, let me see if my understanding -- and you can
feel free to correct me if my historical perception in
this area is inaccurate.
When we originally licensed these plants,
credit was given for overpressure for MPSH because of
the physical fact that it was running and intact, and
the coolant loses its density because of its elevated
temperature if there was going to be containment
overpressure.
That in recent years, we became less
confident in that as a safety margin, and we
questioned whether that overpressure was appropriate
to grant overpressure.
And there are some plants that are
licensed to use the containment overpressure. That is
an irreversibly fact of life, but we are nervous when
we grant these things.
MS. KAVANAUGH: We are getting nervous
because they are requiring more. If you look at the
original analyses, it was a pound here, and less than
a pound. Now we are getting into time periods where
they are needing 5 or 6 pounds for several hours.
MS. KAVANAUGH: So, yes, that is where the
level of uncomfortable comes from.
DR. SCHROCK: What is the basis of the
confirmatory containment analysis? What method is
used?
MS. KAVANAUGH: I did not do that
analysis. That is something that we can discuss
tomorrow, but I believe they used the contain program.
DR. SCHROCK: I am not going to be here
tomorrow.
CHAIRMAN WALLIS: There is no tomorrow.
MS. KAVANAUGH: Oh, okay.
MR. SHUAIBI: Again, the lead reviewer on
this is not here, but we can discuss that at the full
committee meeting. We offered to do that.
DR. SCHROCK: I won't be there either.
MS. KAVANAUGH: But I believe they used
the contain program as -- do you remember? You're no
help -- the confirmatory analysis code.
MR. BROWNING: This is Tony Browning from
Duane Arnold again. The staff was using the contain
code, and requested a great deal of data from us so he
could benchmark his model to our containment design
and specific parameters so that he could do the
confirmatory analysis. So that is how it was
performed.
DR. POWERS: Any other questions?
CHAIRMAN WALLIS: Well, if these plants
don't meet the guidelines, maybe what you need is a
new set of guidelines which logically explain a change
in position, and explain the rationale for giving
credit for these overpressures.
MS. KAVANAUGH: That is a good point.
CHAIRMAN WALLIS: And then set some limits
to what is acceptable based on some criterion, which
might even be related to risk or something that we can
grasp a hold of.
Would it be unreasonable that you
recommend that you rewrite the guideline to be more
specific, and explicit, and rational?
MS. KAVANAUGH: I believe at one point
-- and I don't remember specifically, but I believe it
is Reg Guide 182, that also deals with MPSH analysis.
And there was an effort at one time to
combine the safety guide in with that, because that
deals with vortexing and all kinds of fun stuff, and
into one reg guide which would explain that. But I
don't know where the staff's effort is on that
initiative or not.
MR. BOEHNERT: How many plants are
affected by this?
MS. KAVANAUGH: I would say we have 2 or
3 PWRs, which are multiple unit sites; and I would say
about 12 BWR sites. You will find that the newer
units don't run into this problem. Their MPSH
requirements on their pumps are extremely low.
DR. POWERS: Thank you.
MS. MOZAFARI: By way of concluding, I
just wanted to reiterate a little bit that the staff
used the ELTR-1 and 2 as the framework for the review.
It was more or less the outline that they followed to
see that everything got addressed.
They used the Monticello safety evaluation
more or less as a template to kind of scope the depth
of the reviews. Plant specific design differences
were addressed, and that's why you ended up with a
foot of documents.
Usually it was the back and forth of
questions that the staff asked Duane Arnold
specifically about their design and submittals. And
then these were followed up by follow-ups from
telephone conferences that supported the staff
reviews, and documented by the information requests.
This pretty much lays out the scope of the
review, and it is consistent with the ELTR-1 and 2,
and the way it was provided, and it pretty much does
address all areas.
Further guidance on review is provided by
the SRPs in the different systems areas. And they did
follow their SRPs. And this states what the staff has
concluded in the draft safety evaluation, and will be
seen again in the safety evaluation, that all areas
affected by the extended power uprate have been
reviewed and evaluated.
And all the methodologies used for
extended power uprate analyses are acceptable to this
staff for this application; and the results of the
analyses were acceptable, and there were cases as we
have indicated where we did confirmatory analysis.
The PRA results showed an acceptably small
increase in risk associated with the extended power
uprate, and therefore the proposed extended power
uprate of 15.3 above CRTP, which is 20 percent above
the original license power level is accepted for Duane
Arnold. Are there any other questions?
DR. POWERS: Well, thank you. What I
would like now is to move to a discussion with the
committee to discuss what we want to present --
MR. SHUAIBI: Dr. Powers, Mohammed Shuaibi
again. There were a couple of questions that came up
earlier, I believe, that you wanted to talk about,
namely grid stability and something with containment
hydrogen and questions that came up about that. We
have people here to address those questions if you
want.
DR. POWERS: I think we got the answer on
the grid stability.
CHAIRMAN WALLIS: And that the oxygen
didn't meet the requirements, but somehow or other
that was acceptable for some reason. Was that the one
that you were mentioning; the 5 percent oxygen
requirement.
We were told that they didn't meet the
requirements at the start of the event, but for some
reason this was judged to be okay because it was not
a time where you really needed to worry about the
issue or something.
It was a reassurance that the staff has
good rationale for allowing the licensee not to meet
requirements. That's all.
MR. PERALTA: This is Jim Peralta from the
Plant Systems Branch. There is a period of
approximately 24 hours where after the LOCA where the
hydrogen monitors would not operate as accurately as
they are supposed to.
The licensee has stated that they in fact
will be indicating somewhat high, which would be a
conservative direction, and it is essentially on that
basis that we accepted it.
CHAIRMAN WALLIS: So it would seem that
they would meet the requirements if they overestimate
something and then they are conservative, and then
they are essentially meeting the requirements; is that
correct?
MR. PERALTA: Yes.
CHAIRMAN WALLIS: Were there requirements
written in some way that doesn't reflect this ability
to be conservative?
MR. PERALTA: The point was that the
instrument wouldn't be working as it was originally
intended to work because it would be outside of its
deign parameters. However, it would be indicating in
a conservative direction, yes.
DR. POWERS: And were certain that nothing
irreversible happens to this device?
MR. PERALTA: Well, I don't know that we
asked them that specifically, but that certainly is
implicit in -- well, they said after that period of
time that it would begin operating within its design
parameters. That it would go back to operating within
its design parameters.
CHAIRMAN WALLIS: To monitoring hydrogen?
MR. PERALTA: Yes.
CHAIRMAN WALLIS: And there was a five
percent oxygen requirement that you are trying to
verify, or is that something else?
MR. PERALTA: As far as I know, it is the
hydrogen monitoring. I didn't see anything on oxygen.
CHAIRMAN WALLIS: That they monitored
oxygen, and that they reached the 02 limit one day
earlier without the power uprate. Maybe this also
needs come clarification. Perhaps again we could have
something written to the subcommittee so we can look
at it before we have to go before the full committee.
MR. BROWNING: Excuse me, Dr. Wallis.
This is Tony Browning from Duane Arnold again. These
are combined monitors. They monitor both oxygen and
the hydrogen content in the containment. So you are
monitoring both.
CHAIRMAN WALLIS: They are conservative
about oxygen or hydrogen, or both?
MR. HUEBSCH: This is Steve Huebsch from
Duane Arnold. They are conservative when the
containment temperatures are higher than the heat
trace temperature, and the analyzers are conservative
for both.
The issue that comes up then is the fact
that if they aren't within their accuracy bounds for
the Reg Guide 197 criteria, the operators could
perform an action prior to needed.
That was part of the discussion early on.
So if they were reading your five percent oxygen level
at a point where --
DR. KRESS: It is really 3 percent.
MR. HUEBSCH: Yes, and if it is only 3
percent, the operators might be in a situation where
they would attempt to perform compensatory actions to
deal with high levels of oxygen/hydrogen.
So one of the things that we have
identified is that when you get into the EOPs and
start looking at the event that you are talking about
2-1/2 days, or 2.3 days by the analysis, before you
would ever get to the situation, and that is via a
conservative calculation.
What we can do with the analyzers is even
though the temperatures caused this over prediction in
the analyzers, or a slight over- prediction when they
get down close to the heat trace temperatures, they
still do trend.
So the operators can watch a trend in
increasing levels over time for the first 24 hours,
and they will be able to tell where their
hydrogen/oxygen levels are leading.
We have also got calculations that we have
had in the past that compensate for those. We don't
have those calculations currently in our operating
instructions because when we installed the heat trace,
we took those out.
The one thing that we are looking at now
is we are saying that we have the ability to trend the
hydrogen/oxygen levels. They will be a little over-
predictive until the containment temperatures drop
within the band of the heat trace.
And the calculations show that that will
occur within the first 24 hours, and the conditions
won't affect the analyzers adversely.
So once the 24 hours period comes down the
operator can look over, and in essence what we have
done in the EOPs is that he can look at the
temperatures in the containment, and make the
assessment of the accuracy of the --
CHAIRMAN WALLIS: But the argument is no
longer that they are conservative because they are
reading high. It's whether or not they mislead the
operators because they are reading too high, and then
you are going to have to have proper operator training
to not be mislead by this reading, which is due to the
fact that you put a heat source close to the sensors.
MR. HUEBSCH: They have already had the
training as part of the operation.
CHAIRMAN WALLIS: So this is acceptable
because the staff accepts that the operators will
still take the right actions because they will know to
not misunderstand these faulty readings. Is that the
way the staff resolves it? That wasn't the
explanation that we got first.
DR. KRESS: Well, if the operators take
the action that was intended at the wrong time, it
still would be an effective action, and the safety
issue is a question of if you guys don't want to mess
up your operations by having them do it when they
didn't have to. Wouldn't that be a better way to
characterize it?
MR. HUEBSCH: Yes. Their compensation
would be to inject --
DR. KRESS: So if they did make an error,
it's not a fatal error.
MR. HUEBSCH: No. You would inject the
CAD, and you would add a nitrogen mask to the
containment, and still stay within the pressure limits
because the system was designed that way. You would
mitigate it with a change of time sequence for events.
DR. KRESS: Yes.
CHAIRMAN WALLIS: Well, maybe what is
indicated here is that this was a draft SER, and when
you write about oxygen and hydrogen that it will be
clarified in the final SER.
Now, what is the procedure then? Do we
actually have to look at the final SER?
MS. MOZAFARI: We are in the process of
getting the final SER done, and you would see the
final SER, but I believe that what we are looking for
is that any questions that you refer to us, we will
evaluate those in concert with the final SER.
CHAIRMAN WALLIS: I am wondering if we
should have a full committee meeting before we have
this final SER? We have had this debate before, where
there was something about the SER that we were unhappy
about, and then something got approved, and before we
got to approve something that was in draft form, with
the assurance that something would be fixed. I wonder
if that is the appropriate way for us to act.
MS. MOZAFARI: Well, we would expect to
get your comments, but I think that some of the issues
that you were commenting on we were planning to
present at the full committee anyway, and we would
incorporate any suggestions into the final safety
evaluation, and so they would be addressed.
DR. POWERS: Well, how much time has the
committee allocated for this?
MR. BOEHNERT: We have -- let's see, about
an hour-and-a-half, from 8:35 to 10:15 on October 4th.
MR. SHUAIBI: I guess that question is to
the ACRS, but what I would offer is if we can provide
you written responses to those questions that you
have, and provide you an explanation of our review
process at the full committee. We would rather do it
that way, but obviously it is up to you.
DR. POWERS: I would like to talk to the
members now about what they would like to see the
staff and the licensee present, and I would begin with
the licensee.
My personal bias is that we ask the
licensee to give a fairly summary discussion of what
he has done to change his plant and then to present
his PRA results, perhaps with even a little more
detail on the work that he has done on human
reliability, and also some human error analysis,
because I think my rationale for doing that is that
that gives him this summary opportunity to speak to
the committee, in terms of the language which it
likes, which is risk.
I think he has done some things that I
think are innovative there. At the same time, he
needs to give a summary of the things that he needs to
change in his plant, which look to me to be fairly
minimal.
DR. KRESS: I agree with what you say,
Dana, with one exception. I think the power uprate is
being reviewed on the basis of compliance with the
regulations.
DR. POWERS: It is.
DR. KRESS: I think the committee would
want to and would need to hear how they -- the story
about how they are complying with the various limits
that they have to meet for the power uprate. So I
would have what you said, but I would want to see a
summary version of the compliance also.
CHAIRMAN WALLIS: We need to hear more
about ATWS don't we in the full committee? That seems
to be one of the compliance areas.
DR. POWERS: Well, my thinking with regard
to the ATWS -- or at least what I was thinking of --
well, Tom is right. This is a compliance application
and what not.
Quite frankly, the licensee is electing to
deal with ATWS in a way that we have already seen. He
is not introducing a great deal of innovation. He is
following a plan that has been developed by GE, and if
memory serves, we discussed at length.
There are some subtleties to it that I
don't really fully understand that we could go into,
but I thought it would be better to go into those
compliance issues with the staff.
I think we have to make a decision on what
we would do here, because given the amount of time --
DR. KRESS: We don't have a lot of time,
that's for sure.
DR. POWERS: And what I don't want to do
is get the licensee and the applicant into a position
of having to give such a summary presentation that all
he does is everybody sits around and -- that the full
committee just gets confused, because they haven't all
seen this.
DR. KRESS: I think the plant changes and
the PRA summary both go pretty fast.
DR. POWERS: I think we need to decide
-- well, the way they handled the PRA in the
presentation to the subcommittee was a fairly lengthy
package, but a short terse presentation as befits its
role.
If we wanted to keep it that way, then I
think it is no more than a view graph showing the
bottom line results, and not any greater discussion on
that.
DR. KRESS: I think the view graphs that
show what led to the bottom line results have a few of
them, but mostly human error is based on the human
error changes, and is based on the timing. I think
those would also be appropriate to have in there,
because that is the whole basis for the changes.
And this discussion on the use of
compliance for the events, I think that belongs or
could be part of it.
DR. POWERS: So what you are basically
saying is that you would like to see a summary of
everything that was presented?
DR. KRESS: Well, no. They went through
a great deal of trouble to answer all the ACRS
questions that we put to them ahead of time. I don't
really think we need to go through those again.
I think they just give the slides to them
or something, and let the rest of the committee read
them. But I don't see how we can avoid going through
the compliance part of it.
DR. POWERS: I wasn't going to avoid that.
I was going to go through that with the staff.
DR. KRESS: Oh. Well, that may be, but I
don't know if the full committee will be pleased with
just saying that they did all the calculations using
approved codes and met the limits.
DR. POWERS: Well, I think we have to give
them something fairly specific. I don't think we can
say give us a summary and then come back and say,
well, that wasn't enough detail. That just is not
playing fair.
So let's talk through the topics that were
presented and say do we want to hear about that or
not.
DR. KRESS: Okay.
DR. POWERS: Okay. They have compliance
with regulatory requirements, and they have hardware
modifications, analyses performed, and impact on plant
margins.
DR. KRESS: I think I want to hear those
and the whole basis of that.
CHAIRMAN WALLIS: That is the whole basis
for the decision.
DR. POWERS: If they are going to go
through it, then we are going to hear it again from
the staff. That's the thing that I was trying to
avoid.
CHAIRMAN WALLIS: Well, they went through
that fairly briefly.
DR. POWERS: All right. We have plant
operator training, stability monitor/instability
avoidance.
DR. KRESS: I think I can do without both
those.
CHAIRMAN WALLIS: What we really need to
do is the stability if you want to show anything at
all. There is orange curves and that you can actually
get up past them, and things --
DR. KRESS: Yes.
DR. POWERS: Okay. So we want to go
through that. ATWS event response for uprate
conditions.
CHAIRMAN WALLIS: I am tempted to ask the
staff why they accepted the ATWS response, but that
may take a long time.
DR. POWERS: You are going to get that
opportunity.
CHAIRMAN WALLIS: We don't need to go
through all the details of that.
DR. POWERS: Well, I think it is do they
go into it or not. There is nothing detailed in the
45 minutes that I am going to give them. I mean, we
have got an hour-and-a-half.
CHAIRMAN WALLIS: Well, I think we have to
have something about ATWS, because ATWS is going to
turn out to be the power influences to the PRA later
on isn't it? So I think you have to say something to
that before --
DR. POWERS: Graham, I understand what the
problem is, but they have got 45 minutes, and so that
means they get 23 minutes to talk. That means that
they get one view graph on each one of these topics,
or we yell at the planning and procedures, because
they have only give us an hour-and-a-half here.
DR. KRESS: I think that is where the
problem is.
CHAIRMAN WALLIS: Well, I think you have
to say that ATWS was handled in the standard way, and
what has changed here is that the operators have to
respond quicker. That's what they have to say. Can't
they say that quickly?
DR. POWERS: No, because someone like you
will ask them something that they don't feel obligated
to answer.
CHAIRMAN WALLIS: It won't be me, but I
know who it might be.
DR. POWERS: But there are committee
members who have been known to ask questions at least
as detailed as yours. Okay. Is there any topic on
here that they don't need to go into?
DR. FORD: You could argue that materials
degradation -- if you are talking about the time
available, materials degradation issues, I have got my
own opinion as to how important they are or not.
And I have put myself in the position of
your technically informed person out in the public,
and how they would react to presentations given today,
in terms of the amount of quantitative data from the
assessment on material degradation issues. Dana, I
don't know if those minutia should be covered in the
full committee meeting. I would suspect not, but I
would hate to see our recommendations not taken
account of.
DR. POWERS: We will get to draft a letter
and provide the committee with a summary. I can't
imagine your esteemed colleague from Oregon sitting
quietly and having been drugged through the details of
ATWS response not getting at least a chance to hear
the word CHECWORKS.
So if you are going to go into this
detail, we are going to do it twice; once with the
licensee and once with the staff, and we had better
cover them all.
I would hope they would not have to go
through the discussion with the dryers and the
separators. They are not safety issues, and nothing
emerged out of this that suggests that that would
change. But that is the only one so far that I have
been able to take off this list.
I mean, what you are saying is that you
would like to see a compact version of this, the
presentation that they prepared for us yesterday
afternoon.
DR. FORD: Apart from the dryers and
separators, which I agree with you, the safety issue
is the question of the quantitative treatment of the
VIP vibration criteria for stress corrosion and
cracking.
The details of the FIV, which I personally
don't believe is a big problem, but as presented,
somebody could turn around and say it is not
adequately supported in the information given. And
the other one is the one that you brought up, the CUF
factors, and why are some up and some down. What is
the rationale.
I personally don't think that these are
big deals. But to someone outside this room, you
don't see any evidence that they are a big deal. Do
you understand my point? In what venue do you sort
these things out and do you record preservation of
those?
DR. POWERS: Right now I am only trying to
give guidance to the licensee on what he is going to
have to present. We have given him no help whatsoever
because all we have said is that we want to hear four
hours of presentation in 23 minutes.
And I don't think he is going to dance at
his daughter's wedding over this one.
DR. FORD: I am quite willing to put my
hand up and say don't mention it given the time, and
I don't think there is any need to have a big
discussion on materials degradation.
But I would hate to see it in the public
environment, where this is not enough sufficient
quantity for discussion.
DR. POWERS: Well, there are multiple
things that go out on a public venue, and the staff
evaluation report is a public document, and does go
into this subject.
DR. FORD: But is it worthwhile for me
just to write down my comments here and give them to
the staff? Is that good enough?
DR. POWERS: There is another public
document, and that is the ACRS letter, and I am not
sure who it goes to right now. There are multiple
avenues for bringing this up.
It appears to me that the recommendation
of this subcommittee to the licensee on what he
presents -- and understand that the licensee can use
his own good judgment on what ought to be presented --
is that you attempt to go through the Items 1, 2, 3,
and 4 in the agenda, and 5.
And I would suggest that in light of the
time limitations that you not go into the PRA results.
It is not part of their application. It is going to
provoke a lot of discussion, and you haven't got time
available to you to cover it in a way that you will
find satisfactory the items that are being presented
to you.
And Dr. Ford has suggested that you can
limit the amount of discussion that you do on the
corrosion substantially. I think the committee has
been through CHECWORKS as an entity in some detail in
the past, and those that have an interest in it have
all been through it fairly in detail.
I think if you want to approach the
subject, it is adequate to say that you looked at flow
erosion using the CHECWORKS methodology, and let it go
at that.
Otherwise, it sounds like most of these
things they want to address.
MR. MCGEE: Could I review the list once?
DR. POWERS: You certainly can.
MR. MCGEE: This is Ron McGee. So you are
requesting that we would cover next week during the 23
minutes allotted --
DR. POWERS: You will have 45 minutes and
we usually count that in 45 minutes that we have had
quite a cross-section of the committee here. So you
might shade that a little bit, and take a little more
time.
MR. MCGEE: Thank you. So, the plant
modifications and then regulatory compliance, and the
analysis performed, operator training, thermal-
hydraulic stability, the ATWS response, fuel response
for ATWS instability, and material degradation --
DR. POWERS: I think that you can handle
that with one sentence there. If somebody else had a
question, I think that can be pretty promptly handled
because you are using fairly standard methodologies
here, or that are familiar to the rest of the
committee. There is nothing ground breaking in this.
MR. MCGEE: Okay. Our containment
analysis.
CHAIRMAN WALLIS: I think you would have
to show your justification for your MPSH. I think you
have one summary curve that shows the containment
pressure and the pressure required, et cetera. It has
been an issue, and it is something that the staff has
raised. So you have to make your case for that.
MR. MCGEE: We can skip the steam dryer
and separators.
DR. POWERS: I think you can.
MR. MCGEE: ECCS analyses.
CHAIRMAN WALLIS: That's the bottom line.
I think you need to have a bottom line; that of the
1300 and something degrees. You need to reassure that
you will meet the criteria.
DR. POWERS: Yes, and I would approach
that with a little caution, and make it clear that you
have two limits, and why you have two limits, and why
you comply with both of them, just because that is
new. And you can go on to say that the second one may
actually evaporate one of these days or something.
CHAIRMAN WALLIS: Now, why is he skipping
PRA?
DR. KRESS: Don't have the time.
CHAIRMAN WALLIS: I think he has to show
the PRA bottom line. I think you have to show the
bottom line on any issue that is significant.
DR. POWERS: Graham, I know something
about some of the members of the committee, and if we
ask them to show a bottom line on the PRA, those
members of the committee will say a bottom line isn't
good enough for me.
CHAIRMAN WALLIS: Then we are going to
need to have more time. This is the place where the
licensee makes the case in a public forum that an
uprate should be granted, and it has got to be a fair,
comprehensive case. It doesn't have to be detailed,
but it has got to cover main arguments.
DR. POWERS: The PRA is not part of the
case.
CHAIRMAN WALLIS: Well, it is a
consideration, and I think the conclusions here are
kind of similar.
DR. POWERS: I feel a responsibility to
comply with what the planning and procedures have
given me for time, and I am afraid that if just giving
a bottom line on the PRA is --
CHAIRMAN WALLIS: It is going to be asked
anyway. It's not going to be asked for anyway?
DR. POWERS: And that is the other thing.
Remember, I came in here with a going in position of
just doing the PRA.
CHAIRMAN WALLIS: And that's why I
wondered why you flipped completely.
DR. POWERS: Because I can't ask them to
do everything in 23 minutes.
CHAIRMAN WALLIS: Then they need more
time.
DR. POWERS: I could ask them to do
everything if I gave them the whole morning. I would
keep my PRA results in my pocket, and just hit them
with the bottom line numbers on it. And if it is
provocative, I will take the time out of Wallis' hide.
CHAIRMAN WALLIS: I have a topic that we
can vote on in five minutes.
DR. POWERS: What did you say?
CHAIRMAN WALLIS: I am very happy to take
some time out of my topic.
DR. POWERS: I think you have done -- I
actually think you have done some innovative things
with the PRA that would be of interest to the
committee.
MR. MCGEE: The information that we
provided yesterday, all the slides and stuff, will
that be provided to the full committee prior to our
meeting with them?
DR. POWERS: That would ordinarily not be
the case. They could get it if they asked for it.
But that would not ordinarily be the case that they
would have it.
DR. KRESS: Quite often we have had people
come in with a package like that and say we are not
going to present this, but if you would like to read
these, here is a group of slides that tells you.
DR. POWERS: And as I said, I think you
have done some innovative things with your PRA that I
wouldn't be stunned if you advertised it. I think you
have done an evaluation and in screening your human
performance issues using PRAs to identify things.
And I think what you did for screening of
components that is in your PRA was an innovative act
in your application. I would have enjoyed exploring
with you just to see how you did it and whether it was
useful, and whether you would ever do it again.
But I think you have time to perhaps
discuss that with individual members if they ask
questions, and you may be able to present the bottom
line numbers and what not.
The trouble is that this committee -- the
full ACRS committee, their eyes tear over and they put
hands on their heart when the word PRA comes up, and
they have more questions than most people would ever
be able to generate answers.
And here we are focusing more on power
uprate issues, which of course you are doing
innovative things there, too. Now, I would like to
come to the staff presentation at this meeting.
And I will begin again with my suggestion
to the committee, and see if they will overrule me,
just as efficaciously as they did with respect to the
applicant.
It seems to me that opposing sets of
questions for the subcommittee meeting, in the
interest of efficiency, we may have sandbagged the
staff a little bit. And that we need to give them
more freedom to design their presentation.
And I would encourage them to design their
presentation to dissuade the committee from writing a
letter that begins, "With the ACRS unable to ascertain
if the staff has done an adequate review of the Duane
Arnold application for a power uprate. Our
examination of the SER suggests the staff has asked
perceptive, probing questions. Documentation of the
resolution of these questions in the SER is quite
limited has become the familiar pattern for SERs."
"Our discussions with the staff did not
produce satisfactory amplification of the SER. Too
often the staff appears to have accepted a methodology
that has been proven in the past without showing that
it has also done an adequate investigation into the
application of the approved methods."
"After oral discussion with the staff, it
is not apparent that the staff is adequately familiar
with either the methods or the specific application."
I think that I would like the staff to
make a presentation that forecloses writing that kind
of a letter.
CHAIRMAN WALLIS: In 45 minutes.
DR. POWERS: In 45 minutes.
CHAIRMAN WALLIS: With questions.
DR. POWERS: With questions. I think the
areas that the subcommittee has pursued in here give
you some guidance to what we are looking for when we
say have you done an adequate application or
investigation on how it was applied to the specific
issue here.
I think we are in general familiar with
those approaches that the staff has accepted in the
past, and it is really how they were applied that is
at issue here.
And as I said, when I read the SER, I
found -- my general impression in reading the SER were
the questions that the staff was asking were the right
questions. In fact, they were very good.
It's that their final resolution doesn't
come through as clear and clarifying. I am giving you
my personal viewpoint, and I will turn to the rest of
the committee and see what they would like to hear
from the staff.
DR. KRESS: Personally, I will bite off
from what you said. That would have been my
recommendation.
DR. POWERS: Professor Wallis, have you
any guidance that would like to give the staff on
their presentation?
CHAIRMAN WALLIS: Well, I think you have
given them a challenge. I'm just wondering how they
will respond to it. I guess I will just have to wait
and see.
DR. POWERS: I remain confident that they
can, because again I looked at the SER, and I looked
at the kinds of questions that were being asked, and
addressed, and I thought that they were perceptive and
challenging questions.
CHAIRMAN WALLIS: The only thing that I
worry about is the committee getting into some of the
morass that we got into; is that when we start probing
the rationale for the decisions, we have difficulty
getting answers to the questions posed. I don't want
that to happen with the full committee. The answer
should be crisp and to the point and reassuring.
DR. POWERS: Professor Schrock, can you
give us some help here?
DR. SCHROCK: Probably not. I have been
concerned for a long time about this issue of the
falling back on the fact that analyses are done in
accordance with previous approvals, and frequently
that gets in the way of communicating an understanding
of what is done and how it is applied in the present
situation. I think you have said that very well.
And I am glad to hear that challenge
thrown up to the staff. I think that is something
that needs to change and it needs very badly to
change.
So apart from my strong feeling on that,
I don't think I can give you a lot of guidance on how
you are going to cope with your problem of getting all
this information exchanged in this short period of
time.
DR. POWERS: And Dr. Ford.
DR. FORD: I have four specific questions
that you can pass on to the staff.
DR. POWERS: Oh.
DR. FORD: You are giving them a
challenge, and I am giving them four specific
questions to help them meet the challenge.
DR. POWERS: Very good. Do you want to
share them with us?
DR. FORD: Well, we have already gone
through it in the other meeting. It is the CDF
situation and FIC, and FAC, and the corrosion/ erosion
cracking. I can give them to you. I have gotten them
written out.
DR. POWERS: Okay.
MR. SHUAIBI: Dr. Powers, can I ask a
question?
DR. POWERS: Certainly.
MR. SHUAIBI: This is Mohammed Shuaibi of
the staff again. Is it your perception that the
entire safety evaluation is this way, or is it just
inadequate in certain areas?
DR. POWERS: I did not in the course of
the presentation find an area that we asked questions
in that I thought was handled in a way that was
reassuring. Well, I take that back. I found the
answers to the NPSH margin questions by the section
head were answered promptly and explicitly.
MS. KAVANAUGH: Thank you.
DR. POWERS: Now, the criterion question
that Dr. Wallis asked still is more nebulous, but I
don't know that you are responsible for that in this
application. Okay. Any other comments that the
members would like to make?
Have we given you -- I'm sure that we
haven't given you enough, but would you like to hear
me talk anymore?
MS. MOZAFARI: No, I think we have an
idea. We will go back and revisit our conclusions,
and our evaluations to make sure that we have been
clear enough about the basis for the evaluations.
DR. POWERS: Feel free to interact with
Mr. Boehnert, who will be in a position to pass on any
clarifications that you might need.
MS. MOZAFARI: Okay.
DR. POWERS: With that, I will turn the
meeting back to Professor Wallis.
CHAIRMAN WALLIS: I would like to thank
the representatives from Duane Arnold and GE, and the
staff, and my colleagues for their contributions to
this meeting, and I will adjourn the meeting.
(Whereupon, the opening meeting was
recessed at 12:20 p.m.)
Page Last Reviewed/Updated Tuesday, August 16, 2016
Page Last Reviewed/Updated Tuesday, August 16, 2016