Thermal-Hydraulic Phenomena - October 26, 2001
Official Transcript of Proceedings
NUCLEAR REGULATORY COMMISSION
Title: Advisory Committee on Reactor Safeguards
Thermal-Hydraulic Phenomena Subcommittee
Docket Number: (not applicable)
Location: Rockville, Maryland
Date: Friday, October 26, 2001
Work Order No.: NRC-082 Pages 225-356
NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers
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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
(ACRS)
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FRIDAY
OCTOBER 26, 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 8:30
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. WILLIAM SHACK, Member
DR. VIRGIL SCHROCK, ACRS Consultant
DR. JOHN D. SIEBER, Member
ACRS STAFF PRESENT:
PAUL A. BOEHNERT, ACRS Staff Engineer I-N-D-E-X
AGENDA ITEM PAGE
Introduction by Chairman Graham 227
Dresden/Quad Cities Uprate 227
NRR Presentations
Subcommittee Caucus 340
P-R-O-C-E-E-D-I-N-G-S
(8:30 a.m.)
CHAIRMAN WALLIS: The meeting will now
please come to order. This is a continuation of the
meeting of the ACRS Subcommittee on Thermal-Hydraulic
Phenomena, at which we discussed the proposed extended
power uprates for Dresden and Quad Cities.
And we heard yesterday from Exelon, and
the licensees, and today we are going to hear from the
staff. I would call on John Zalenski to get us
started.
MR. ZALENSKI: Thank you so very much. I
guess I am a little bit of a bump in the road, in that
I wanted to take a couple of minutes to talk to the
letter you sent with respect to the Duane Arnold
facility, and its marriage or association to Quad
Cities and Dresden.
Our staff is fully prepared to get into
the details of the review on Dresden and Quad Cities,
but I thought it would be worth a couple of minutes to
highlight that your letter has made quite an impact on
me personally and on the office.
And one of the issues that I thought I had
addressed before the full committee had been my keen
desire to ensure that we were going to indeed have a
first-rate product before we ever approved that
license amendment.
The status of that particular safety
evaluation is that it is not ready to be served, and
using a phrase that I have used many times in the
past, we will serve no wine before its time.
The technical basis will be robust for
each of those given sections, and I would submit that
it would be our intent to provide some sort of a
highlighted version for your easy review for
information purposes once we get to the point where
that is rating the issue.
In a small way to show what I believe to
be a substantive difference between an early draft and
the product that actually goes out the door, and
hopefully that may be a little bit closer to some of
the expectations of some of the members.
So to the product itself, I don't want to
forecast or say that we are going to have it done next
week, or the week after, but we are putting our
shoulder down to ensure that the first one out of the
shoot is done correctly, and it meets management's
expectations, and is indeed robust.
As we go forward the staff sometimes
relies on previous work and that will be kind of an
example the staff will rely on. So it has got a high
mental, and you have helped us in an interesting way
to ensure that the mental is put at the right height.
There were a couple of other issues in the
letter that -- oh, by the way, we will be responding
to the letter formally, but, I really wanted to
scratch an itch a little bit and if there was
discussion, I would be more than happy to take some
questions.
The staff should develop and improve
guidance on the detail in the safety evaluation. I
read this as a generic comment to how the staff does
licensing work, and we will probably respond in that
manner.
And some of this is driven by our internal
processes. We do have a quality initiative that has
been germinating for the past year. It is funded for
this fiscal year with a senior management leaving that
particular activity, John Hannon in our plant
activities branch.
I think we will have a lot to say about
this issue over the next year, and the criteria on
independent assessments, and things of that sort, I
think we will probably be talking to you considerably
about a lot of the guidance that currently exists, and
a lot of the expectations that currently exist, and
probably do a little bit better job in assuring how
our reviews are performed.
I am struck by the young lady that rose at
the full committee and said I reviewed this document,
and I reviewed that, and I did a lot of these. But
none of that ever made it to the safety evaluation.
In so many words, we are going to go back
and ask ourselves should we be a little bit more
candid to here are the actual things that were done,
and so I think in short this has certainly got my
attention, and as we go through Duane Arnold, the bar
height will be established for what we see for other
licensees, and the draft that you received from us on
Quad Cities and Dresden is not at that level.
But yet I would not anticipate it having
not gone through any management reviews. So if there
are any questions, I would be more than happy to take
those. Otherwise, I would begin turning the meeting
over to Mr. Bajwa.
I will say that I have asked that a number
of our senior management team responsible for
oversight of the reviews attend this particular
subcommittee meeting.
Mr. Hannon is here, and Dr. Barrett and
Mr. Vermeil, and a number of our senior management
team out of the two principal divisions in support of
this particular meeting.
So by elevating our attendance to some of
our managers and section chiefs, I am trying to
overtly indicate that we have heard what you have
said, and we are trying to be responsive.
If there are no questions, I would be more
than happy to get into the subject at hand at this
time.
CHAIRMAN WALLIS: Well, no, I just wanted
to thank you for what you have said. It is very
helpful.
MR. ZALENSKI: Okay. Good. Mr. Bajwa was
the project director for Region 3 plants. He is also
our lead senior SES responsible for power uprates.
And I have asked him to provide some
opening comments on the work that the staff has done,
and then our project management team and our technical
review team stand prepared to address a variety of
review areas.
There is one topic area that we will touch
on that we have not come to resolution with Quad
Cities and Dresden, and that has to do with integrated
testing.
And should these plants be expected to
perform testing of the MSIVs, should they be expected
to perform other tests, such as suggested in their
generic topical report -- and one that comes to mind
is the load reject test, today we are simply not in a
position to say that we think that those tests are
necessary to confirm all the work that has been done
by the staff.
My own sense of this is that the decision
on whether to test or not is independent of can we
approve this license amendment. In other words, I
don't believe that any of us feel that conducting the
test if necessary to move forward with the technical
work or not performing the tests.
So we have more work to do and we will
have that issue resolved before we issue the
amendment. We just did not have enough time to take
it through the various levels of management to ensure
we are aligned within our organization.
So with that as kind of an opening
comment, why don't you go ahead and get started,
Singh.
MR. BAJWA: My name is Singh Bajwa, and
moving on to Quad Cities and Dresden, I would like to
say that we have conducted a thorough review of the
Dresden and Quad Cities plants in all areas
potentially affected by the power uprate.
We conducted our review from existing
practices, including the lessons learned from the
Maine Yankee experience, although we reviewed
information in many areas of the licensing basis of
Dresden and Quad Cities units.
And beyond that, we have used this
information, and we will focus our representation
today on the areas that we believe to be most of
interest for our power uprate.
We will also address areas that the ACRS
has expressed an interest in. So as John mentioned,
we have one open issue which we will not be able to
speak to it because it is a pre-decisional at this
point.
But as John indicated, we will inform ACRS
at the time we issue the safety evaluation in its
final form. With that, I will now turn this to Larry
Rossbach, the lead project manager for the Dresden and
Quad Cities power uprate reviews.
Larry is also the NRR project manager for
the Dresden plant. Also at the table is Mr. Stu
Bailey, the NRR project manager for the Quad Cities
plant.
Larry will give an overview of the review
process used for this application and agenda for the
meeting. He will also introduce the other presenters
at the table.
MR. ROSSBACH: Thank you, Singh. My name
is Larry Rossbach, and I am a project manager for the
NRR, and I am the project manager for Dresden, and
also for the power uprate project for Dresden and Quad
Cities.
Briefly, to go over our review process,
the guidelines we use, we use the generic G.E.
guidelines, and generic evaluations topicals, ELTR-1
and ELTR-2.
These licensing topical reports have
previously been accepted by the NRC as an acceptable
guideline for power uprate applications. And the
staff uses these topicals as guidelines in our review.
In addition, we use the existing NRC
standard review plan and we rely on previous power
uprates. Specifically, the safety evaluation for the
Monticello Nuclear Generating Station was used as a
guide for the scope and the depth of the review.
In addition, Dresden and Quad Cities
reviews were really done in parallel with the Duane
Arnold review, and in some areas even used the same
reviewers. So it should look familiar to you being
done in the same format as the G-topicals, and being
reviewed in the same manner in-house.
As John Zalenski had said, we are on the
Dresden-Quad Cities project of the comments on the
Duane Arnold safety evaluation, and we have taken
those into account to the extent that we could,
although most of the reports that you have was written
prior to receiving those comments, and we are
continuing to work to improve that safety evaluation.
As we progress in our review, we do
sometimes identify the need for additional
information, and so there was substantial additional
information submitted by the licensee in response to
our request.
The staff also performed three audits
during the conduct of this amendment review. The
Reactor Systems Branch audited global nuclear fuels
analysis at the G.E. facility in Wilmington, North
Carolina.
the probablistic safety assessment branch
staff audited the licensee's risk assessment process
at Exelon's midwest offices, and the plant systems
reviewer audited analysis at the Dresden site.
The principal areas of our review -- and
again, very similar, and the same as in Duane Arnold,
but the staff reviewed the results of the licensee's
evaluations in reactor core and fuel performance, and
reactor coolant systems, and containment analyses, and
emergency core cooling system performance evaluation,
and instrumentation and controls.
And the suitability of existing ones and
the proposed modifications. The electrical power and
power conversion systems, and auxiliary systems, and
radiological consequences, special events and limiting
operational transients.
And probablistic risk assessment review,
and we reviewed human performance aspects of the
submittal, and there was an environmental assessment
done. The environmental assessment will be published
separately in the Federal Register.
I would like to go over briefly the order
of our presentation. The reactor systems review will
be gone over by Ralph Caruso just to my left, and the
plant systems review will be summarized by Ralph
Architzel.
Following that, we will respond to ACRS
questions in other areas where we had not prepared a
full presentation. As time allows, we may get into
more detail in those areas.
And they include -- and this is partly in
response to questions that we received from the ACRS
dealing with material degradation issues, pipe
support, pipe and support modifications, the need for
electrical modifications, and the PRA analysis and
evaluation which we did.
With that, I would like to turn it over to
Ralph Caruso.
MR. ZALENSKI: If I might just jump in for
a second. As our staff goes through the presentation,
it would strike me that it would certainly be fair to
query which code standards, which reg guides, standard
review plans, acceptance criteria, specific regulatory
requirements, the staff is working against.
And the staff should be able to clearly
explain what we did to independently determine that
something was acceptable. And so seeding your thought
a little bit, that would be my expectation to find
that kind of information in the final report.
MR. CARUSO: Good morning. My name is
Ralph Caruso, and I am chief of the BWR nuclear
performance section and reactor systems in NRR,a nd I
am going to talk about the nuclear reactor and fuel
systems review that was done as part of the
Dresden/Quad EPU review.
I am going this with the slides being a
little bit out of order, the package that you have,
and so I am going to do my presentation the old
fashioned way here, and I think I have a crib sheet
here that tells me where you should be turning as I go
along, and I will call out the slide numbers that you
have got.
The first one is slide 10, and that has
got my name on it. The second slide is slide 11, and
this is the background. This is a power uprate of
approximately 18 percent from the original rated
normal power level.
It involved implementation of MELLLA and
ARTS, reactor trip system. It also involved the
introduction of GE14 fuel into a core that is
currently supplied by Siemens.
The staff, as part of its review, in
addition to the review in-house that we normally do,
performed an on-site audit at GNF-Wilmington. This
looked at compliance with the analytical methods that
we have approved and that are being applied by GE to
analyze this reactor's behavior.
And this includes something called G-STAR
Amendment 22, which is the process that they used to
develop and approve the GE-14 fuel design. We
performed audits of the Dresden and Quad Cities EPU
system performance, and a design basis safety
analysis. And we reviewed as it says here the safety
analysis reports.
DR. SCHROCK: Ralph, before you leave
that, I have a question on the first item. One of the
problems that I mentioned yesterday in connection with
the review of this large quantity of paper that was
received is the fact that we essentially had two sets
of things that were verbatim to a major extent.
And it was very difficult to sort out the
things that were different for the different plants,
and I pointed out in the beginning that as I tried to
do that, I found that in the SARs that the MELLLA
graphs are not the same for the two plants.
And the response to that was initially
that, yes, they thought that they were the same and
they should not be different. But subsequently I got
the two reports side-by-side, and indeed they are
different.
So what is then confusing is why are they
different? What is the explanation for why the MELLLA
is different for the different plants, and why is the
response from the plant owners that, yes, they should
be the same, when in fact they are not the same?
MR. CARUSO: It is not clear to me. What
do you mean by they are different, and in what sense?
DR. SCHROCK: They are different in the
sense that different points have different valves.
The slope of the main MELLLA line is different on the
different graphs.
The full power, full flow point, is the
same. Everywhere else on the graph, the lines are not
the same.
CHAIRMAN WALLIS: And on the left-hand
side the boundaries are very different I think.
MR. CARUSO: Well, I can't speak to the
specifics of exactly where the points are. I am not
surprised that they are different, because the plants
are different, because the fuel designs are different,
and because the fuel management schemes will be
different, because they are implementing different
fuels at different points in life, and there is a lot
of core design that gets done, which will change those
curves.
So I am not surprised, and so are you
looking for an explanation of exactly why the points
are slightly different?
DR. SCHROCK: Well, there are two parts to
the point that I am trying to make, and the question
that I am trying to raise; and the first one is the
detail of what is correct about the SARs. Should
those things be different, and should they be the
same.
I am confident that I heard pretty clearly
yesterday from representatives of the industry that
they ought to be the same. Now, you are saying that
they ought to be different, and I am not surprised
that they are different.
MR. CARUSO: I am not surprised that they
are different.
DR. SCHROCK: So there is a point to be
resolved there. But the overall point that I am
trying to get across is that it makes for a very
inefficient process to be put in the position of
having to sort out differences between two plants that
are being resolved simultaneously when these
differences are not highlighted in the documentation
that is presented.
And where you get two stacks of paper
which you ought to expect to have to digest in some
detail, and what you find is that they are essentially
verbatim, like 95 percent plus.
And then you have to discover what is the
reason for numbers to be different in the two plants
when there is no explanation in the documentation,
either in the SARs or in the SERs. That is the problem
that I am trying to get across to you.
DR. KRESS: Your MELLLA line is not a
fixed thing. It ought to vary throughout the whole
life of the core actually.
MR. CARUSO: I would expect it to vary
from reload to reload.
DR. KRESS: Yes, and from reload to
reload, and so I guess it depends on what they choose
to analyze when they put the thing together.
MR. CARUSO: Right. That's why I am
saying that I am not surprised that they are
different, and I can't speak to the particular details
of each curve. Let me ask my staff if they have any
insights as to why they might be different?
MR. KENDRICK: This is Edward Kendrick,
reactor systems branch. First of all, the Quad and
Dresden plants, the pre-EPU are different power
levels. The post-EPU is the same thermal power.
So the post-EPU MELLLA lines I believe
should be virtually identical. And since they started
from a different one and they used in many cases a
bounding Unit 5, there could be some differences.
The staff, in preparation for the audit,
looked first at Dresden, and then specifically at
Dresden-2, which is the lead unit. And we identified
the differences, first of all, between Dresden and
Quad, and then the differences between Dresden-2 and
Dresden-3.
Now, we did not include a table in the
SER. We could do that because for our information we
had to go through and look at Dresden, and then go
through and look at Quad. So I think in the SER we
can tabulate the differences, and why there are
differences.
MR. CARUSO: And a great deal of our
review did not necessarily look at and verify each
individual point on those curves, because the way we
do the reviews is to do a sampling to ensure that the
methodologies that are being applied are being applied
correctly.
So we don't necessarily review every
individual number and verify each and every individual
number.
CHAIRMAN WALLIS: Well, I was going to ask
the question that my colleague asked in a different
way. I was going to ask did the staff realize that
these figures, which are key, the power versus flow
maps, are different for the two plants?
And did they then ask why.
MR. CARUSO: I don't believe that question
was explicitly asked, because as I said, I am not
surprised at all that they are different.
CHAIRMAN WALLIS: I know, and you can say
that, but the thing is were you aware until my
colleague mentioned that they were different that they
were different, and that is the thing that --
MR. CARUSO: I don't think that I
explicitly had -- that it crossed -- well, I don't
know. Ed, did that cross your mind? He is nodding
yes. He did notice that.
CHAIRMAN WALLIS: I think the natural
circulation line is significantly different, for
instance, and I don't know why it is different.
Anyway, we should probably get off of this point. We
have now started asking questions.
MR. CARUSO: Okay. Review Scope, and this
is Slide 12. As part of the review, as I said, we
have looked at fuel design and operation, and this was
Amendment 22, and something that we audited at the GE-
Wilmington facility.
Thermal limits, and reactor coolant
system, and connected systems, ECCS performance, the
capability of the standby liquid control system, and
design basis and safety analysis, and ATWS and ATWS
instability. This is the scope.
And Slide 14 will be next. As Larry
Rossbach said, we followed the scope of the ELTR-1 and
ELTR-2, and the Supplement-1 to ELTR-2, to guide us in
our review. And once again in the reactor systems
area -- and that's what I am here to focus on -- all
of these analyses were done in accordance with NRC
approved methodologies, analytical codes, and they are
all met NRC approved analytical limits.
And those limits would range from the
numbers in the regulations, such as 2200 degrees and
17 percent oxidation in 50-46, to the general design
criteria requirements that 99.9 percent of fuel rods
not experience boiling transition during a transient
event.
CHAIRMAN WALLIS: I'm sorry, but I am
going to go back to the previous question. You said
that specific points weren't calculated or checked on
the power versus flow map. I'm sorry, but my mind is
following a train of thought here.
MR. CARUSO: Okay.
CHAIRMAN WALLIS: How did you satisfy
yourselves that the MELLLA upper boundary was in fact
in the right place?
MR. CARUSO: Well, as part of the audits
that were done, the staff reviewed the calculations
that were done for linear heat generation rate for the
LOCA analyses, and for the transients.
And the MELLLA line will be developed as
part of that process. So we reviewed particular
points in the process to ensure that the process was
being followed, and the MELLLA line was therefore
appropriate.
DR. KRESS: You reviewed the process
instead of the product.
CHAIRMAN WALLIS: Did you make any
independent calculational checks or anything?
MR. CARUSO: No, we did not.
CHAIRMAN WALLIS: So you checked off that
they went through the right process?
MR. CARUSO: No, we didn't check it off.
What we did was that we sent people to the GE-
Wilmington facility to look at detailed calculations,
to look at the inputs and to look at the outputs.
And to determine whether the assumptions
that were made were appropriate and within the stated
limits and the approved methodologies. And that the
outputs were in accordance with the acceptance
criteria.
CHAIRMAN WALLIS: Well, the reason for
asking the question is because this is a very key
point, because you are saying that they are arguing
that it is now possible to go up to this limit, this
boundary.
It is now possible to operate in a region
where we have not operated in before, and this is the
boundary of the new region. So you have to be really
sure that you are on good ground if you approve that
boundary or the methods that led to that boundary.
MR. CARUSO: In the reactor systems area,
we are -- I don't want to say we are unique, but I
think we are probably ahead of other organizations,
other parts of NRR, other disciplines, in that we have
a well-founded base of analytical methods that have
been reviewed and approved, and that we have a lot of
experience with.
These methodologies have been reviewed and
we have -- we do have our own analytical tools that
have been used to verify these methodologies, and we
feel that as long as licensees and vendors use those
methodologies within the acceptance criteria, and
within the limits of application,we do not feel a need
to do additional independent assessment unless we have
specific credible information which would cause us to
doubt those codes are being applied inappropriately.
And in the case of these power uprates,
because the peak bundles are not changing, and because
the flow rates are all within current methodological
limits, we didn't feel that there was any need to do
any independent assessment.
DR. KRESS: If you did want to do an
independent assessment would you use RELAP and NAMONA,
or is --
MR. CARUSO: It would depend entirely upon
the area. If it were a LOCA case, we could use TRAC-
B, and we could use RELAP. In the area of stability,
we could use ROMANA. Well, ROMANA is the one that
comes to mind. I think there may be some other codes.
But we have contractors available to us,
and Jose Marsh Luba, the expert on instability, and we
would call on him if we felt that there was something
about the operation of this plant that placed it
outside the appropriate methodology.
But because of the way that they did this
power uprate, everything stayed within the appropriate
limits, and therefore there was no credible reason for
us to doubt that the methodologies were not being
applied correctly.
We do occasionally -- I mean, the reason
that we do these audits is because these power uprates
called into question whether the methods were being
applied correctly.
That was a prima facie case for doing an
audit, and that's why we started doing the audits at
Duane Arnold, and that's why we continued doing them
for Dresden and Quad Cities.
And that's why we continued for Clinton,
and that was done, I believe, in September, and I
believe that we are planning going out and doing a
Brunswick audit sometime later on this winter.
So we are looking at these things to check
to make sure that the methodologies are being applied
appropriately, but without some credible specific
issue. We don't believe that we have the resources to
go do an independent assessment.
CHAIRMAN WALLIS: Well, an issue might
arise -- and I haven't done this yet, as my colleagues
have been looking at these curves in more detail, but
if we started to compare them and we found that there
were really big differences between this MELLLA
boundary in one reference than another, then I think
we might ask at the full committee meeting again why
this is so -- and it might indicate that someone
perhaps needed to check into it.
And you are saying that you didn't have a
good reason to want to make an independent assessment
of the question, and that may well be true.
We began to question it because we noticed
that there were these differences, that's all.
MR. CARUSO: I understand that, but as I
said, realize that these changes occur from cycle to
cycle, and the staff normally doesn't even do reload
reviews. They can make changes to these parameters
without our knowledge when they change fuel designs,
and when they change core designs.
And we would not even see them except as
a report after they start off. That could cause --
DR. KRESS: They basically develop a new
MELLLA line for every reload don't they?
MR. CARUSO: That's correct. That has to
be reevaluated every reload. All of these analyses
have to be done every reload. And they are done in
accordance with these approved methods, and we feel
comfortable enough with those methods that we didn't
think that we needed to do independent assessments.
DR. KRESS: Did your audit go to the
extent of checking the input to the codes to these
methods?
MR. CARUSO: Yes.
DR. KRESS: So you really did look at the
inputs?
MR. CARUSO: As I described I think to
this committee, or maybe it was to the full committee,
we had four people that went to the plant, and they
asked for what are called the design record files, and
these are the detailed calculations that support
operation.
And they sat down in a room and they read
them. They went through them page by page looking at
the inputs, and looking at the outputs, and looking at
the assumptions.
And then they asked questions, and they
sat down with people like Jason Post, who is standing
up and he wants to say something.
MR. POST: Yes. This is Jason Post. I
have a couple of things. One is that the differences
that you see in the power flow maps between the two
units are mostly in the natural circulation line, and
the minimum pump speed line.
And those were not -- those are historical
differences between the two sites, and we did not try
to reconcile those differences for this, because that
really was not pertinent to the change that was being
made.
CHAIRMAN WALLIS: I don't understand the
term historical. I mean are they meaningfully
different, or is it some mysterious history?
MR. POST: It has to do with the
instrumentation and the analysis that was done at the
time that those plants were first built. And the
difference is not as great as it is shown.
CHAIRMAN WALLIS: Well, if they are
similar plants, you would expect natural circulation
characteristics to be pretty well the same wouldn't
you?
MR. POST: Yes, you would.
CHAIRMAN WALLIS: So why are they so
different on a map?
MR. POST: As a result of the improved
methodology over the years, some of the plants have
gone back and redefined their natural circulation
lines. My guess is that one of the units has done
that a little more accurately than the other unit.
But again that wasn't something that was
pertinent to this design change to MELLLA and EPU. So
that was not addressed in this license amendment that
historical difference was maintained.
CHAIRMAN WALLIS: Well, maybe if we asked
the question again at the next meeting, you will have
an explanation other than history?
MR. POST: Certainly.
CHAIRMAN WALLIS: Can you have an
explanation other than that?
MR. POST: Certainly. The other statement
that I wanted to make was that while the actual power
flow relationship can change from a cycle to cycle
basis, the MELLLA line itself is a licensed limit, and
that as a licensed boundary does not change.
And that licensed boundary is drawn to be
bounding over the actual power flow relationship that
can change slightly from cycle to cycle. And Israel
is just coaching me here. It is also common to both
plants, and so the MELLLA boundary itself is identical
between the two sites.
It's just extended to a lower core flow in
one to match the natural circulation line, which is
lower.
CHAIRMAN WALLIS: Thank you.
DR. KRESS: So Virgil's observation that
the slope is different is not true? The slope is
actually the same?
MR. POST: That is correct.
MR. CARUSO: It is not the same on the
graphs.
MR. POST: Excuse me. I believe the slope
is the same on the two SARs. It's just that the lower
point, the lower left-hand point, is different. So it
might appear that the slope is different.
CHAIRMAN WALLIS: This is something that
we can easily verify since we have two different
points of view, and we can do a test at the break and
see who is right.
MR. CARUSO: My next slide is actually
Slide 21 in your package. And it is the reactor core
and fuel performance slide. And one of the questions
that often comes up is a question about margin, and
who owns the margin.
And as I stated earlier, we have a number
of different cycles specific, and licensing thermal
limits. And the licensing limits, like the 2200
degrees, and the 86 gallons per minute for the
standpoint liquid control system, and the 99.9 percent
limit for the transient, those are the fixed limits.
And licensees are free to work within that
boundary as much as they want. They own that margin.
CHAIRMAN WALLIS: And they did in this
case.
MR. CARUSO: And they do.
CHAIRMAN WALLIS: And 1600 became 1600
exactly, for instance.
MR. CARUSO: That's acceptable.
CHAIRMAN WALLIS: And 1500 psi became
1499.
MR. CARUSO: And I will be honest, as the
first question that I asked when I saw the number was
how many times did you have to run it to get results.
CHAIRMAN WALLIS: We asked the same thing.
We asked about do loops and things.
MR. CARUSO: And I got a very indignant
response. He said that the first time that we ran it,
it was 1499 and that is what it was.
DR. SHACK: I wouldn't run it again
either.
DR. KRESS: Your statement that the
margins are available to the licensee, does that have
qualifications to it? Like it is available if they
are using the same approved codes that they used
before?
MR. CARUSO: Absolutely. They have to use
the methodologies within the limits that are defined
in the SER, and they have to meet the appropriate
acceptance criteria.
DR. KRESS: So if I go in and change my
code, and improve the code, do I still --
MR. CARUSO: We could spend all day
talking about changes to the codes.
DR. KRESS: Yes, I understand.
MR. CARUSO: There are rules about this,
some of which are better defined than others, about
when changes have to be re-reviewed, and it depends on
whether it is a LOCA code, or a transient code, or a
stability code.
And we have disagreements about that now
and again. But generally as long as they stay within
the acceptance limits, then they can wander within the
box. And occasionally we see people do very creative
things, and we try to convince them of the error of
their ways when they do that.
Once again, as I said here, this is an
unusual power uprate because it was based not on any
one particular plant. Most of the analyses were done
for what was called Unit 5, and it was a bounding
analysis of some plant that doesn't actually exist and
that had parameters that bounded all of the four
Dresden and Quad Cities units.
But our determination was that this
equilibrium bounding unit -- the analysis of this
equilibrium bounding unit demonstrated that the
thermal limits are acceptable, and that the cores that
will be designed eventually in the future to be used
in these plants can be appropriately designed, and can
be appropriately operated.
CHAIRMAN WALLIS: Could you say what the
thermal limits are again, and what you mean by it?
MR. CARUSO: Up here on top, we have a
safety limit minimum, minimum critical power ratio,
MCPR.
CHAIRMAN WALLIS: Those are things like
the 2200 degrees and things like that?
MR. CARUSO: Some of these are 2200, like
the LOCA limit to the right is there, and the safety
limit, MCPR, and its derivative, the operating limit
MCPR, are there to show that you meet the 99.9 percent
boiling transition.
CHAIRMAN WALLIS: Were these evaluated
for -- I don't quite understand, but for some typical
cores, which is a bounding -- some typical bounding
unit?
MR. CARUSO: Yes.
CHAIRMAN WALLIS: Well, then you are sure
that this is somehow outside all the possibilities of
the various limitations of cause or whatever?
MR. CARUSO: For the purposes of doing the
power uprate, they did a bounding calculation, but
then for each individual plant, for each actual core
design, they will verify that that core design meets
those limits.
CHAIRMAN WALLIS: The numbers that we were
presented with, the 1600 degrees, and things like
that, are the actual specific calculations for
specific plants aren't they?
MR. CARUSO: I think it depends on the
analysis. In some cases, they were plant specific,
but in some cases they were bounding. I seem to
remember some were plant specific, but some were also
bounding.
CHAIRMAN WALLIS: It would seem that
eventually they all have to be plant specific.
MR. CARUSO: That's correct.
CHAIRMAN WALLIS: And one would expect the
number to go down when it becomes plant specific if
the previous one were bounding.
MR. CARUSO: Yes, that's correct.
CHAIRMAN WALLIS: Is that always the case?
MR. CARUSO: I believe so.
CHAIRMAN WALLIS: Does it go down by much?
Is it exactly 1600 in the bounding case, and 1599 for
the plant, or something like that?
MR. CARUSO: I don't think that they are
going to go down to something like 700.
CHAIRMAN WALLIS: I guess if we saw 1600
for the plant, then the bounding unit must have been
somewhere above the limit.
MR. CARUSO: Let's see if I can get
someone from the licensee to answer that.
MR. FREEMAN: This is John Freeman with
Exelon. The 1600 degree was for the upper bound
calculation on the LOCA analysis.
MR. CARUSO: Oh, you are talking about the
LOCA number. Okay.
MR. FREEMAN: I think that is what you
were driving at, and that was a bounding number based
on the Unit 5 approach, which covered all of the fuel
types which were going to be in the reactor.
As far as whether some of them are cycle
specific, or bounding, LOCA -- well, actually, all the
thermal limits get reevaluated on a cycle specific
basis. However, most of them don't change. The ones
that we expect to change are the safety limit MCPR,
the operating limit MCPR. To a lesser extent, the
LHGR, depending on how the center line melt and
plastic strain limits are met.
So that is all done on a cycle specific
basis. However, I think the big issue was the LOCA
analysis, and that is bounding. The ATWS analysis was
bounding.
So we don't expect to see any changes in
those results without changes to the reactor system
design.
CHAIRMAN WALLIS: So this 1600 degree
example that we have here is specific to each cycle.
So it is a variable. It changes all the time?
MR. CARUSO: Well, in this case, I think
as the GE -- I think Dan Pappone did that presentation
yesterday. And he explained that they have a 1600
degree limit in the GE methodology. So they may --
CHAIRMAN WALLIS: But the 1600 is the
actual as well.
MR. CARUSO: And they calculate 1600 as
the actual number, but they may vary the MAPLHGR
limit, the linear regeneration rate, to stay below
that number.
So they will use 1600 as the limit, and
they will vary the heat generation rate to make sure
that they stay within it. The number may stay the
same, and --
CHAIRMAN WALLIS: And part of your
licensing procedure is not just to say they have
calculated a number which you approved of, but to say
that you trust them to keep calculating it and to keep
it below your limit?
MR. CARUSO: Yes, that's very important.
CHAIRMAN WALLIS: And you trust them to
keep calculating it all the time because it is cycle
specific?
MR. CARUSO: That's a very important
point.
CHAIRMAN WALLIS: And not to let it go
over the limit.
MR. CARUSO: That is a very important
point, yes. We trust them to do these calculations
appropriately. But we also verify from time to time
that they are.
CHAIRMAN WALLIS: So when they show us a
number which is exactly on the border, 1600 calculated
equals 1600 allowable, then this is for a particular
calculation at a particular time that is implied with
sort of our approval of that if we approve it, and
they are going to keep doing this, and they are not
going to allow themselves to go over that?
MR. CARUSO: That's correct.
CHAIRMAN WALLIS: And that they didn't
understand at the time?
MR. CARUSO: That's correct.
CHAIRMAN WALLIS: And presumably they
found that they were going over it? What would they
do, shut down the plant until they corrected something
or what?
MR. CARUSO: No, they have to revise some
aspect of either plant operation or core design to
make sure they stay below it.
CHAIRMAN WALLIS: So they might then
operate at a reduced power?
MR. CARUSO: Exactly.
DR. KRESS: They can only go over it on a
hypothetical basis.
CHAIRMAN WALLIS: Of course, it is a
calculation.
DR. KRESS: It is a calculation.
CHAIRMAN WALLIS: Okay. Thank you.
MR. CARUSO: Let's see. My next slide is
Slide 28. Let's see. I have a general discussion
here about system performance. We looked at the
systems.
For example, the RCI system, the high
pressure injection systems, and the low pressure
injection systems, to see whether they would perform
their design functions at the higher power, higher
rated power.
And because this was a constant pressure
uprate, those reviews were not very difficult to
determine that those components would operate
appropriately, because they see the same steam
pressure, and they see the same reactor pressure. Most
of the bounding parameters remain the same for these
systems.
DR. KRESS: How did you decide that the
isolation valves would perform their function just as
well at the new uprate?
MR. CARUSO: The isolation valves.
Actually, they have to be able to close on critical
flow. If you have a pipe break outside the MSIV --
DR. KRESS: I understand, and the heat
didn't change?
MR. CARUSO: The pressure didn't change.
DR. KRESS: Yes, but T did.
MR. CARUSO: T? Temperature?
DR. KRESS: Critical flow is squared over
KGRT. It is steam. It is close enough.
MR. CARUSO: I don't think it matters.
Why did the heat change?
DR. KRESS: Well, I thought you changed
the outlet temperature.
MR. CARUSO: No.
DR. KRESS: Just the amount of steam flow?
MR. CARUSO: The steam flow rate changed,
but the steam pressure stays the same.
DR. KRESS: So your blow down rates are
about the same.
MR. CARUSO: They would be about the same.
DR. KRESS: And your pressure is about the
same.
MR. CARUSO: Right.
DR. KRESS: So the loads on the valves, if
they could close before, they can close now is what
you are saying?
MR. CARUSO: Exactly.
DR. KRESS: Okay.
MR. CARUSO: Let's see. My next slide is
Slide 29. As I said, they performed the LOCA analyses
for the bounding unit using an equilibrium GE-core.
This is the core that they eventually
expect to get to once they replace all the Siemens'
fuel in about 2, 3, or 4 cycles with GE-14 fuel.
And we looked at the -- as part of our audit, we
looked at the pre-EPU and the EPU analyses for LOCA.
These were done with the SAFER/GESTR
methodology that was described yesterday, and as we
have discussed in the past, the peak limiting bundle
for these analyses doesn't really change.
So there was not much to look at in terms
of changes to the methodology, and changes to the
inputs to reflect the fact that it was a mixed core,
Siemens fuel and GE-14 fuel, and it changes because it
is GE-14 fuel which is going in for the first time.
But other than that, the methodology was
applied appropriately, and the LOCA analyses
demonstrated compliance with 50.46.
DR. KRESS: This particular ECCS, to deal
with LOCA, is it a head spray, or where does that come
in at?
MR. CARUSO: I need assistance. This says
-- well, Dresden has high pressure coolant injection.
How many high coolant injection pumps? One high
pressure coolant injection pump.
DR. KRESS: And that is in the head coming
down on top?
CHAIRMAN WALLIS: It is a ring spray, a
ring with a lot of nozzles on it.
MR. CARUSO: It is a low pressure core
spray.
CHAIRMAN WALLIS: We are asking the staff
if they know or if they understand the system, I
guess.
MR. CARUSO: Well, you are asking me off
the top of my head, and I don't have all 37 BWRs in my
head.
CHAIRMAN WALLIS: I know. I understand
that.
DR. KRESS: Well, part of my question is
to see what you guys looked at, and the other part is
if you flatten out the core profile, and you have got
more steam coming up around the edges, and less in the
middle.
And you are basing your validation of your
code for these ECCS based on something like the old
tests in Germany and Japan, which didn't have a core
profile. It had a different one.
And does this put into question the
validation of the codes that are used to calculate
these peak clad temperatures?
MR. CARUSO: Interestingly enough, this is
one thing that we did actually talk to them about,
spray distribution.
DR. KRESS: Yeah, carry over and the spray
distribution. Right.
MR. CARUSO: And it came up in a
relationship to an issue involving license renewal of
the BWR, and we were concerned about spray
distribution over extended -- of a plant at the end of
60 years, and would it still have the same spray
distribution.
And in talking to G.E. about it, we
learned that spray distribution is not important for
the early part of the LOCA because of the assumptions
that are made as part of the analysis. They don't
assume a particular distribution, but for the long
term cooling portion of the LOCA analysis, spray
distribution does become important.
And let me see if I remember the logic
here, because this gets very convoluted. Late in the
LOCA sequence, the distribution is acceptable. I am
trying to remember the reason why we discussed this
with them.
CHAIRMAN WALLIS: Early in the sequence,
you have got a pool don't you?
MR. CARUSO: Exactly, and that's why --
DR. KRESS: The pool is up on the top.
CHAIRMAN WALLIS: But then how the pool
drains will depend upon the amount of steam coming out
of all of these channels, which is now different
because you have gotten more heat source on the
outside from the decay heat.
DR. KRESS: And the question was how much
of that drained and how much got carried out.
CHAIRMAN WALLIS: Well, there is a
different pattern of drainage, too, because of the
flux distribution.
MR. CARUSO: This was discussed. We had
a real long discussion with them about this.
CHAIRMAN WALLIS: It was discussed, and so
you are really sure that you are on good technical
grounds?
MR. CARUSO: Yes.
CHAIRMAN WALLIS: And you looked at the
effect of the new distribution of heat source across
the core on the draining of that pool during a LOCA?
MR. CARUSO: Yes. The explanations are
very reasonable. I was going to suggest at some point
that it might be a good idea -- well, I won't talk
about that now.
CHAIRMAN WALLIS: Well, you didn't find it
necessary to do any independent verification
calculations or anything on those phenomena?
MR. CARUSO: No.
CHAIRMAN WALLIS: Because I guess one of
the generic questions that ACRS raised before was when
do you decide to do your independent verification
calculations, and when do you accept what you see from
the applicant.
MR. CARUSO: And as I said earlier, if we
-- when we are using these approved methods within
their acceptance criteria, we would do independent
calculations if we had some specific and credible
reason to believe that they were not appropriately
being applied.
If we had some issue that had been raised
by staff members, by the Office of Research, by the
ACRS, by outside interested parties, that said they
didn't consider this particular aspect.
And there is no way you can tell that from
their analysis, and then we might do an independent
analysis in that case. But realize that the
methodologies have been validated in many instances
against the NRC codes already.
CHAIRMAN WALLIS: We have no way of
independently checking this. We just have to ask you
and sort of believe that you have done the job.
MR. CARUSO: You would have to dig through
piles, and piles, and piles of topical reports.
CHAIRMAN WALLIS: That's correct.
MR. ZALENSKI: For closure on this issue
did I hear a comment or a question raised regarding
the validity of our codes based on new data becoming
available from Japan?
DR. KRESS: No, the comment was that the
codes -- that their validation was based on old data
mostly, I think, and those used actual flux
distributions that were not as flat as these.
And the question is does that put into
question the validity of them, because it is based on
old data with the wrong flux distribution.
MR. CARUSO: Our question really had to do
with the spray distribution, and to make sure that
there was the spray distribution that was assumed as
part of the analysis.
DR. KRESS: Yes, it is the same issue. Is
the flux distribution going to maybe affect the spray
distribution.
MR. BOEHNERT: And whether the tests are
still applicable.
DR. KRESS: So that was the nature of the
question.
DR. SCHROCK: I guess I wonder how
confident a particular analysis is bounding.
MR. CARUSO: Generally, you mean?
DR. SCHROCK: Yes, in general. Do you
scratch your head and say now why is this one bounding
when I am going to make some changes?
MR. CARUSO: Well, that is one of the
reasons that we did the audits. We sent people down
to actually look at the inputs that were used, and the
people that did the audits, like Ed Kendrick here, are
experienced in core design and analysis methods.
And they know which parameters are
sensitive, or which parameters can affect those
analyses, and they looked at the bounding analyses and
determined that G.E. had used the appropriate
conservative values as inputs. And they ran a number
of sensitivity cases to verify that.
CHAIRMAN WALLIS: Oh, G.E. ran them?
MR. CARUSO: G.E. ran them. That takes me
to my next slide, which is Number 30, which is what we
did as part of the audit reviews. Fuel thermal
limits, which is transients; and reactivity
characteristics, and stability.
And we looked at detailed calculations in
each of these areas to verify that they were done
appropriately.
CHAIRMAN WALLIS: This is a check of
paperwork?
MR. CARUSO: It is a check of the
calculations.
CHAIRMAN WALLIS: It is not an interactive
thing, where you look over someone's shoulder and say,
well, how about trying this and that, and let's see if
it is really bounding.
MR. CARUSO: No, but because it was done
at the vendor site, and when people had questions
about what was in the paperwork, they could
immediately ask the people who did the work and get an
answer. They are interactive in that sense.
CHAIRMAN WALLIS: And that wasn't actually
sort of together running the code to see what happened
under certain circumstances or that you were curious
about?
MR. CARUSO: No.
CHAIRMAN WALLIS: It would be interesting
if you could do that sort of thing.
MR. CARUSO: We are about to do that for
one of the advanced reactor reviews. In this case, we
didn't feel that it was necessary. Are there any
questions about the audits? If not, my last slide is
Slide Number 33, Conclusions.
CHAIRMAN WALLIS: I guess it is hard to
know, and I guess what I am thinking about here is how
do we satisfy you did a good audit? Well, I guess an
example would be if you had a case history where you
found something, and if the audit found nothing, it is
a kind of evidence-free situation.
And we don't know if it is good or bad as
you didn't find anything, maybe because you didn't try
hard enough or maybe there is nothing there to find.
It is hard to know what to say.
But if you had a case history where you
were actually curious about something, and you
wondered about it, and when you probed deeper, yes,
you indeed found that they really knew what they were
doing, and they convinced you that everything was
good.
That might be a little bit more harder to
convince some independent person that the audit was a
useful exercise.
MR. CARUSO: I will go back to the Duane
Arnold review and something that I said last time.
None of these audits should be looked at in isolation.
It is a series of audits, and we started with the
Duane Arnold review, looking at areas that we had the
most interest in.
And I am going to admit that we had an
anterior motives besides doing the power uprates. We
wanted to understand how the vendors were doing their
reviews.
So we were looking in places that we
really didn't think we would find anything related to
power uprates, but we wanted to just check how they
had done the calculations.
And during the Duane Arnold review, we
found a couple of significant issues. We found one
that led to a Part 21 report, and the next audit that
we did, we decided that we would look at something
different, because we only have a certain limited
amount of time.
So we focused on things where we think we
will find something, and in this case we came up with
a dry hole so to speak. But that's not bad. The next
time we did the Clinton audit. I don't know what to
say about the Clinton audit. I think
-- well, I don't want to talk about it. That is pre-
decisional.
But then we will do another one for
Brunswick, and we will do another one for the plant
after that, and at some point we will get tired, and
we will stop.
DR. KRESS: From the reactor safety
evaluations, your previous slide, I sort of have a
two-part question. For the site calculations, 10 CFR
100, did they redo an origin calculation to get a new
inventory, or did they just scale up the previous
inventory in some way, like using the power ratio
MR. BAILEY: What the did -- this is
Stewart Bailey, and I am the project manager for Quad
Cities. They did run origin for the new core loadings
and for the 24 cycle, and they used that to develop
scaling factors on the critical isotopes.
And they combined that with some of their
previous analysis to evaluate the changes in the off-
site dose.
DR. KRESS: And I have a question to ask
G.E. or that I asked the applicant people yesterday
about the PRA, and the use of LERF. With a different
core inventory, with different power and a different
amount of products in the core, should the definition
of what constitutes an acceptable LERF be the same or
should it change?
MR. BAILEY: I am not going to touch that.
Mark Rubin will.
MR. RUBIN: Good morning. I am Mark Rubin
from the PRA branch. I think we have kicked this
around with the committee a couple of times. It is
certainly a very valid point as we have mentioned
before.
Generally, we see a large variety of power
levels in currently operating plants, and when we are
developing the guidance for Reg Guide 1.174, it was
thought that we should try to be design independent,
and site independent, and go with a LERF that would
certainly be confirmatory on the Commission safety
goals.
We have plants at higher power levels
operating now, and clearly have higher inventory,
given a LERF. We are sticking with the 1.174 criteria
at this time. I believe if we were to start the
licensing plants at significantly higher power levels
than currently operating, we certainly would want to
reconfirm the LERF definitions, but at this time we
think that this is appropriate.
DR. KRESS: Because the power levels are
generally within the mean of the distribution?
MR. RUBIN: Yes, sir.
DR. KRESS: I think that is a good answer.
DR. SCHROCK: How about the way in which
origin is used? And one of the difficulties that I
have in hearing that everything is done with
previously approved codes, the codes can be used in a
variety of ways, and Origin is an example, as it is
designed it is a point reactor.
And so it doesn't do for you any spacial
evaluation of different compositions in different
parts of the core. If you are going to use it to do
that, then you have got to apply it in a particular
way.
Another limitation that it has is that the
composition of the core is constant during a time
step, and so the limitation that you may place on the
time step will have an impact on the accuracy of
results that you get from the application of the code.
So what I am asking is do you look at how
Origin is employed in different parts of the analyses
that are necessary on these evaluations? It comes up
in a number of ways; for the radiological consequence,
for the activities, for a wide range of things.
In a sense, it is a more general question.
It is how do you assure yourself that what you regard
as an adequate previously approved code, which you
then have confidence in the results for a new
application, is being applied in a way that you should
still have that confidence.
MR. CARUSO: Well, for the -- I can't
speak to Origin, because I was not involved in
reviewing the origin code. We don't have the
individual here.
But I think the question is probably also
applicable to the other codes that we deal with, and
I guess you could say, well, how do we know that they
are not doing and creating a notalization, for
example, or creative time steps control.
And the answer is that we when we do the
review of the LOCA codes, for example, we approve
explicit notalizations, and they are required to do
time step studies to verify that the time steps that
are used demonstrate convergence.
There are lots of criteria that go into
approving a method to make sure that people don't use
it too creatively. And if you go look at the way the
vendors have set up their calculational systems, they
are very rigid because they can't afford to have to
defend lots of creative solutions.
And so they do things in rather rigid
ways, and we found this of all the vendors. They all
proceed this way. So it is our experience that with
codes like the LOCA codes, they are rather set in
their ways.
So they don't do things very creatively
with those codes, because it is not worth it to them
from an economic basis, and we try in approving the
methodologies to define the box so that they can't be
too creative.
I can't answer with regard to the origin
calculation, but I understand the question that you
are asking.
DR. SCHROCK: And another question
regarding the approved codes. According to the SAR
and I believe also your draft SER, one of the ECCS
LOCA codes that is in the table of approved codes is
said not to have been previously approved, but to be
currently under review and that is TASK.
MR. CARUSO: Yes.
DR. SCHROCK: Can you tell us the status
of that?
MR. CARUSO: I can give you some history
behind this. This is actually -- this is one of those
examples of something of a change that might not be
considered to be a change.
G.E. had previously been using a code
called SKAT. The same four letters rearranged
slightly different. That was the code that was
explicitly approved in the methodology for -- I
believe it is a LOCA methodology.
And along the line they are allowed to
make changes to the LOCA methods to a certain extent
without our approval. And in this case, they made a
change that involved a change in the name of the code,
and they didn't think it was a change that required
our review.
During an industry audit of their
methodologies, the industry found this change and said
we think you should send this to the NRC for review.
And the staff, when they found out about it, said,
yes, we agree.
So G.E. submitted the code to us for
review, and I just go the draft SER from Tony Ulyses
this morning, and he believes that it is acceptable.
He thinks it is a relatively minor change, and we will
be approving that.
So the change from SCAT to TASC is one of
these changes that they are allowed to do, but we
always do have disagreements about when is a change
significant and when is it not. And those are things
that we can work out with them.
DR. SCHROCK: I guess if my experience is
relevant to what the committee knows about these
codes, there is a large question mark as to what
really the codes contain.
So what you have just described as a
process of approval of a new code, which isn't going
to come to the committee for review, it is one of
about six things that are indicated as being a part of
the ECCS LOCA evaluation, I don't know what they do.
And so I don't know how I can say yes, I
think the ACRS ought to agree that NRR has a sound
basis for saying that they have reviewed all of this,
and it is in fact well accepted. There is something
missing in here as I see it, and I may not be seeing
it the way as members of the committee.
I don't see how you can expect to have
people look at what you have said and accept what you
have said if you don't show them what it is that you
are talking about.
MR. CARUSO: Well, the LOCA codes are an
unusual case, in the sense that 50.46 explicitly
allows licensees and vendors to make changes to LOCA
codes without approval of the staff. It is written in
the regulation.
They are required to report to us
periodically, at least on an annual basis, when they
do make those changes. And the effect of those
changes on PCT limits. But this is in the regulation.
And so it gets -- well, the difficulty is
that it is not spelled out very well in the regulation
what exactly is -- well, I shouldn't say that, because
the regulation does have a criteria. It has a 50
degree criteria when the accumulation of temperature
changes reaches 50 degrees, licensees are required to
make a report to us, and they are required to redo
their analyses.
But when you talk about whether those
changes have to be approved by the staff, the staff
has an opportunity to discuss them with the vendors,
and decide whether they should be reviewed.
But we do approve minor changes to
methodologies all the time without coming in to ACRS.
I am not sure though that you wouldn't want to see
every one of them.
So we make a judgment as to whether
something is major or significant, and we consult with
the ACRS staff to see whether you would like to review
it, and most of the time the answer is no.
MR. ZALENSKI: In fact, there is another
provision in there, in 50.46, when the licensee trips
50 degrees, that is a 30 day report. When they trip
20 degrees, that goes into their annual report as to
changes that they have looked at and anticipated, and
maybe adopted, or maybe not adopted.
DR. SCHROCK: But these are the results of
calculations and the ability to judge that the
calculation is an adequate calculation that I am
really questioning.
CHAIRMAN WALLIS: What you are saying is
that they could put complete nonsense into the physics
and get 10 degrees.
DR. SCHROCK: Yes.
MR. CARUSO: And that's why I said we
tried to write the acceptance of the methodologies in
such a way that they can't be too creative. And we
try to do that, and that's why we like to do these
audits, because these audits give us an opportunity to
go see how creative they are. That's why we thought
that this was a nice opportunity for us.
CHAIRMAN WALLIS: Are we breaking this up
and trying to do --
MR. CARUSO: No, I'm done.
CHAIRMAN WALLIS: You're done?
MR. CARUSO: I'm done.
CHAIRMAN WALLIS: So how many of these
have you covered? I have lost track.
MR. CARUSO: The last one was number --
well, page 30.
CHAIRMAN WALLIS: And all these other
numbers before that you have covered in some other
sort of order?
MR. CARUSO: Actually, a lot of those were
backup slides. I was going to offer those up if you
had questions about particular issues, such as
stability of thermal limits, or fuel design, and I
could give you details.
CHAIRMAN WALLIS: So your bottom line one
of all these numbers here is?
MR. CARUSO: Is Number 33, which says that
they used appropriate methods.
CHAIRMAN WALLIS: And they got appropriate
answers?
MR. CARUSO: And they got appropriate
answers. And we looked at them, and we looked at how
they did it specifically as part of the audit, and we
didn't find anything unusual.
And we have not heard any credible
specific evidence raised that the methods are not
appropriate.
DR. SHACK: Just following up on Virgil's
question. What kind of changes are they making when
they are making these changes all the time? I mean,
can you think of some examples? Are they changing
correlations, or they are not changing numerical
methods?
MR. CARUSO: Well, no, they don't change
numerical methods. They might change a correlation.
I mean, very frequently, they will -- well, for
example, they will come up with a new fuel design.
So they have got to put a new correlation
into the model to account for the new fuel design, and
I have had some people doing a bunch of those. A lot
of times they find errors.
DR. SHACK: Right.
MR. CARUSO: But they are usually minor.
They are minor errors, and a lot of what gets reported
to us is that we have identified that we made a non-
conservative assumption about the start of the ISI
pump, and instead of starting at 28 seconds, it starts
at 32 seconds. Something like that.
DR. SHACK: Okay. A lot of these affect
input assumptions?
MR. CARUSO: Right. A lot of them affect
input assumptions. I can't think of any off the top
of my head that affected internal workings of the
codes.
CHAIRMAN WALLIS: So you said you were
done. What is the next move?
MR. CARUSO: Plant systems.
CHAIRMAN WALLIS: Thank you very much,
Ralph.
MR. BAILEY: Starting on 35.
MR. CARUSO: Oh, let me ask one other
question. Is there anything that I need to take away
from this session as a testing or a query, or
something that you would like us to talk about
specifically at the next session in front of the full
committee that I have not covered?
CHAIRMAN WALLIS: Well, it is hard to say
exactly what will happen at the full committee
meeting. It is a fresh game, you know, and then our
mines will be working between now and then.
MR. CARUSO: But nothing that you can
think of right now?
CHAIRMAN WALLIS: I think you ought to
read the transcript. Does any member have anything
that they wish to add at this time? If not, let's
move on then.
MR. ARCHITZEL: My name is Ralph
Architzel, and I am the lead reviewer for the plant
systems branch review for the extended power uprates
for Dresden and Quad Cities. There were additional
reviewers that looked at various areas during this
review, and they were Ron Young, and he is not with us
today, but other members are here that looked at the
HVAC control room features.
Steve Jones looked at some of the spent
fuel pool issues, and Rob Elliott looked at the
strainer delta-P calculation aspects of it, and it's
not really related to EPU, but it got resolved during
the course of the EPU.
And in addition, Rich LaBelle assisted
with the containment performance reviews, along with
Ben Gitnick, who is our ISL contractor, during the
Duane Arnold audit.
Basically, the plant systems branch -- if
you could go on to the next slide, and the slides are
a little bit changed from what I saw last night.
Basically, the plant systems branch has a
wide breadth of responsibilities. The way that we
performed our review is that it is somewhat different
than reactor systems, but I will go over it right now.
We reviewed the design operation
requirements for the systems, using the UFSAR. We did
examine application for conformance with the approved
topical report, and the statements in the topical
report safety evaluation, and that was quite an
extensive review just to get that information and
digest it, because I was not one of the original
reviewers for the EPU.
We assured Agency regulations and reg
guides are met under EPU conditions, and that is the
reg guide standards, and in this context, you have to
go back to the licensing basis for the plant as well.
So it is not always a straight correlation
for a standard review plan, or for the regulatory
guides. We held telephone conferences, quite a few,
to clarify the applications, and to systems design and
operation, and the responses.
And in that context, these applications
aren't sometimes quite as extensive as what you see on
the FSAR. So there is -- where we search for
additional clarifications are in areas where there
wasn't quite the detail that we felt was necessary to
make the safety decision.
We issued RAIs to resolve questions
regarding the licensee's EPU evaluation results, and
the supplement to documented information. In our
review, we did coordinate with different branches
because we do have a wide breadth of responsibility,
and where others might have the lead.
This included working with the PRA branch
on the impacts on our affected systems, and we worked
with the inspection programs branch on start-up test
issues, and station blackout input with the electrical
branch.
And the radiological source term with
Steve Levine when we are doing the control room HVAC
reviews. Our conclusion was that the EPU did not
adversely affect the operational basis of the
responsible areas that we had under our review. Go to
the next slide.
The next series of slides basically is a
tabulation of the areas where we provided input into
the EPU safety evaluation report. I assume you have
it and that you have read it.
I don't know that I want to go over all
these unless you really had questions. There were
certain areas where we had significant review items,
and I have asked Rick for those, and they are on the
last page, but right now I will just flip through
these areas, unless the committee has any questions.
DR. KRESS: I have a question about the
containment performance, and it has to do with source
term.
MR. ARCHITZEL: All right.
DR. KRESS: There is this alternate source
term that is in 10 CFR 100 to show compliance with the
thing, and there is one for BWRs and one for PWRs.
The question that I have is whether that
is the source term that they used to show that they
meet 10 CFR 100? And does the fact that you have a
different power, should it influence the design basis
source term from the standpoint of bypass around the
suppression pool, and the temperature and
effectiveness of the suppression pool in removing
source terms?
MR. BAILEY: This is Stewart Bailey, the
PM for Quad Cities. The licensee did not go to the
alternate source term as a part of this update.
DR. KRESS: They used the old source term?
MR. BAILEY: They were originally a TAD
14844 source term, and they ran the origin runs to get
appropriate scaling factors, and usually just scaling
up the critical isotopes. They have not gone to
alternate source term yet.
DR. KRESS: Did they take credit for
sprays, containment sprays? I understand that this
particular --
MR. BAILEY: My understanding is that they
did not. They would have to clarify that. Our
reviewer, or the person who reviewed all of the dose
analysis in detail is not here today. But my
understanding is that they did not credit the spray
for iodine scrubbing.
DR. KRESS: But do you know what they used
for a suppression pool decontamination factor?
MR. BAILEY: I don't know that offhand.
DR. KRESS: I guess I would have to ask
the people --
MR. ARCHITZEL: Yes, as that was not
within my review.
DR. FORD: Could I ask a question of the
previous graph about radiological source terms? In
that analysis that you did, you referred to Hydrogen
16. A case has been made that because you are using
Noble Chem that Hydrogen 16 would be reduced.
Was there any analysis that was done as to
how well the Noble Chem is going to stand up to the
high flow rates, in terms of this adherence?
MR. ARCHITZEL: Let me just explain that
my part of that review was basically asking or had
some questions about the use of Noble Chem, and
whether they wanted to credit it for reduced hydrogen
usage, or excuse me, when they came to the limit on
the recombiners.
So there are different aspects that have
been involved on whether they were going to use or
credit Noble Chem, and they stated in their response
to the RAI that that was not their licensing basis.
But they planned to use it.
As far as the aspect that you are talking
about, the degradation of Nobel Chem, I did not look
at that area, and I am not --
MR. BARRETT: This is Rich Barrett with
the NRR staff. A number of questions this morning do
seem to relate to the way in which the radiological
consequences -- the source term, et cetera -- were
calculated, and we do not have our reviewer here
today.
If the Committee would be interested in
having someone here, we could probably arrange to do
that this morning.
CHAIRMAN WALLIS: Maybe you could arrange
for someone to come after the break, since there have
been several questions, and that would be helpful.
Can you do that, Rich?
MR. BARRETT: Yes, we will look into that.
CHAIRMAN WALLIS: Thank you.
MR. ARCHITZEL: At this point, I would
just like to return to the list of areas and quickly
go over them, and then if there are questions, I do
have backups for some of the areas of review.
Main steam isolation valves, residual heat
removal/LPCI/containment cooling and shutdown cooling
systems, are basically the modes that reflect on the
containment response, and not to the heat portion of
that.
DR. FORD: Will the discussion on the
steam separator performance, will that come in later
on in materials degradation?
MR. ARCHITZEL: The discussion is a
limited discussion, and the limited review that I did
on the steam separator performance is strictly to
verify that they were going to test the moisture
carryover and you heard a discussion yesterday, but
that was the response that they got in the REI.
As far as the structural part of the
separators, and what the staff reviewed, that would be
the mechanical engineer --
MR. BAILEY: Dr. Ford, you are interested
in hearing from mechanical engineering on the
structural integrity of the dryer?
DR. FORD: Yes.
MR. BAILEY: I think we can arrange that.
DR. FORD: Well, it is really just the
process that you went through to assess their analysis
that there would not be a big impact of fluence use
vibration, for instance.
CHAIRMAN WALLIS: The loss of parts or
whatever.
DR. FORD: Loose parts analysis, and just
the process that you went through.
CHAIRMAN WALLIS: So you will have
somebody on after the break then?
MR. BAILEY: Yes.
MR. ARCHITZEL: If there are no questions
on this slide, we will go on to the next slide. In
the containment systems performance area, we did
review the containment pressure temperature response,
and this is one of the areas where you may have
additional questions.
CHAIRMAN WALLIS: Did you do an
independent calculations of any of these things?
MR. ARCHITZEL: What we did in the
containment systems area is that we coordinated with
the Duane Arnold review, and the independent review
that was done for Duane Arnold.
I participated in that review and those
calculations, and it contained code that was used
there as the same containment code that was used for
Duane Arnold and Dresden.
We also had those reviewers, Rich LaBelle
and ISL, look over the containment response portions
of the application, and they participated in the
review of the additional questions and the details
that we searched for, in terms of being able to make
our safety decision.
We did not do independent calculations for
the containment response for Duane Arnold and Dresden,
but we relied on that containment response. We may in
the future do additional independent calculations, and
mass energy release is an area that we may look at,
but at the moment it was to compare it to the codes
that G.E. used for this evaluation.
MR. BAILEY: And I guess another part of
that is that we took a look at their inputs and
methodologies. We had done confirmatory analysis of
their containment response within the last 3 years.
So we have looked at what they are doing recently.
MR. ARCHITZEL: And that was more in the
MPSH area, which is a different slide. We did have
those calculations. This may go fairly quickly,
because if there aren't any questions, we can on --
DR. KRESS: Well, the containment dynamic
loads, does that include the loads on the suppression
pool --
MR. ARCHITZEL: Yes, it does, but
basically those loads were bounded as per the EPU, and
aspects like whether or not the -- you know, with the
same pressure as the driving source initially, EPU is
a second order effect sort of on the containment
response.
So there wasn't a tremendous amount of
difference impacted by the EPU except in the long
term. Now, the TORUS temperature went up for two
reasons. One, the analysis methods changed. They
used a more realistic blow down.
That gets the energy into the suppression
pool faster, and they also no assumed thermal
equilibrium between the TORUS air space temperature
and the water and the TORUS, and the higher
suppression pool temperatures, and the MPSH needs were
increased because of the EPU.
And those are the types of things that we
looked at, and we asked for curbs, and we have curbs
for the containment pressure response, and trying to
understand what was happening at different points.
But we did not do any analyses.
The safety relief valve discharge loads
and things like that were not affected, because there
is a time when it affects the drain down, and we also
looked at aspects like with the increased temperature,
and with the squenchers, and the steam that was coming
out of the squenchers intersect with the suction of
the ECCS pumps.
And they provide discussions and envelopes
for that would not be in the phenomena, and so
therefore they didn't have a local pool temperature
effect addressed or limit addressed.
On the very last page, I happen to have a
list of the ones that are on 46, are the areas where
we had additional input, and one of them was the
4.2.5, and there is no more information there than the
net positive suction head.
And I guess I would like to say on the net
positive suction head that that was one of these cases
where it was an existing open issue before the EPU
started.
Most or a lot of our review items or
aspects, the EPU has a negative effect on net positive
suction head by raising that pressure, and therefore
there was an increased demand, and it was addressed in
the ELTR about the potential need for plants to take
credit for net positive suction head, and there will
be an additional need for net positive suction head.
And in this instance, that effect is
there, and we have looked at it. I could show you the
credit they have requested, versus the existing
credit. There is no additional credit requested in
the very beginning of the transient for either Dresden
or Quad Cities.
But with time that credit does go up for
periods of time and it hangs in there longer. So if
I could take a curve and show you how it is affected
if you are interested.
CHAIRMAN WALLIS: Is this still acceptable
to you, that we take this credit?
MR. ARCHITZEL: Right. We tried to
minimize the credit that we allow them to receive. So
the questions were along the lines of did you examine
and replace the pumps, or some type of other mechanism
to reduce the pressure, and of course that was not
economically feasible was the answer that we got back.
So in that instance would the EPU have any
approval for the potential additional over credit. We
looked at it, and it was not a major increase in over
credit over what has currently been granted.
CHAIRMAN WALLIS: And there is no basis
for saying that the pump performance is likely to be
degraded?
MR. ARCHITZEL: Well, the cavitation, they
do have cavitation at Dresden and Quad Cities after
the peak as you heard yesterday. When I went to the
audit, I did see the testing that was done, and it was
like about an hour-and-a-half testing at cavitation
conditions.
And so there is cavitation, and even
though we have granted that credit, they still don't
have enough credit for 290 until about the 10 minute
point, where they take credit for operator action.
The procedures are in place to reduce the
flow for the operators, and so there is no reason to
really believe that it would necessarily go that long,
the cavitation route.
And part of the questions that I was
asking was also to make sure that the operators
actually weren't going to throttle back those flows
and leave the extra pumps running if they did have
sufficient MPSH.
So I guess if the question is if we are
comfortable with the net positive suction head credit
that we are granting, the open issue that existed did
deal with strainer differential pressure.
And it has taken a long time to get that
resolved, and there have been open issues. Actually,
Quad Cities did not have credit for containment over
pressure.
They had an application in-house which we
had not approved. We rejected it because the methods
that they had used were not in accordance with the
URG. Very lately, we have gotten the submittal that
does follow the URG recommendations and SER.
We have looked at it, and we have not
written the SER yet, but that should not be a problem
for this uprate then. But as for the strainer and
differential pressure, and the unique strainers they
have got, they developed a head loss.
CHAIRMAN WALLIS: So the final SER will
explain why you feel comfortable in some detail?
MR. ARCHITZEL: Well, actually the
strainer differential pressure influence in this EPU
was in the conservative or the effect of raising the
temperature actually results in a lowered differential
pressure.
So in that aspect, it is not a concern,
but we will explain that in the SC.
MR. BOEHNERT: What was the issue with the
fuel pool cooling?
MR. ARCHITZEL: The issue for the fuel
pool cooling is strictly the increased decay heat and
how you handle increased decay heat. We are taking
new looks at fuel pool coolants these days, and what
single failure exists, and it turns out that with
Dresden there is a difference between Dresden and Quad
Cities.
And that they use and credit the RHR fuel
pool system, and they have a dedicated RHR -- well,
excuse me, a dedicated shut down cooling system at
Dresden, and Quad Cities has the residual heat removal
mode.
But basically it is the single failure.
We examined the single failure that they are talking
about, and with the RHR pump, it is just identifying
the single failure, and we got into discussions about
do you really have an RHR backup or you don't you,
administratively, and things like that.
And what temperature are you going to go
to, and what are your makeup rates, and do you exceed
the design of 150 degrees or not. You get a little
more detail, and there is very short sentences in the
application.
So finding out all the details of how that
worked, and what administrative controls were in place
to assure that you had a backup, and assumed the right
single failure.
The make-up rates were not really stated
correctly in the application, and so we got an
understanding of it really has significantly more
makeup, and they provided us the boil off rate, and
those types of issues.
CHAIRMAN WALLIS: There is no ultimate
heat sink?
MR. ARCHITZEL: The ultimate heat sink
-- and if you are on to that page.
CHAIRMAN WALLIS: I am looking at the
slide behind you there that says that was an area --
MR. ARCHITZEL: Well, you are one ahead of
my slide, but okay. In the area of ultimate heat
sink, the staff review is not complete on the ultimate
heat site. This is another area -- well, the EPU
effect just for Dresden.
At Quad Cities another fairly short
discourse provided by the licensee, but the basic
bottom line is that with dam failure at Quad Cities,
the pool behind that dam separates from the plant
after a defined amount of time, and that defined
amount of time is what they currently need to provide
portable pumps for their ultimate heat sink.
Dresden is the area where we have not
completed our review at this point, and one of the
principal reasons that I did go to the site to do an
audit on their calculation of the situation.
This is another existing open issue. The
licensee discovered problems with their design basis
reconstitution several years ago, and after they
discovered those problems -- they are dealing
basically with which volumes are available in the
seismic aspects of the system and the timing of the
operator actions.
And we evaluated those conditions before
the EPU, and we provided the region a TIAA response to
what areas to look at, and basically the EPU effect is
to shorten the time period for manual actions go get
portable pumps, and make up into the canal, which they
consider their seismic -- if you will, a seismic
source.
There still is no seismic source from that
point into the isolation condenser. So that is part
of the staff approvals that is really part of the
issue that is still open, but basically the new
information came out fairly late, and the EPU effect
is not significant from a safety standpoint.
We have looked at that, the 4.5 days to
the 4 days is the latest information that we have
received, there is other information, for example,
that with EPU that you need 2.9 million gallons in the
intake canal, versus 2.5 million before.
That is just boiling water, and it is not
really what you really need, and so the 30 days is not
-- and whether that was in their licensing basis is
questionable. So it is not clear if there ever were
a 30 day type of a plant.
And these are just discussions in the
history that we are evaluating. And there are also
aspects that are currently under review, like proposed
modifications to add a seismic Class One capability
within several years for the IPEEE.
CHAIRMAN WALLIS: I was going to ask you
about seismic. Are you the right person to ask?
MR. ARCHITZEL: I can describe my
understanding of what is seismic and what is not
seismic with the Dresden plant.
CHAIRMAN WALLIS: Well, we were given this
IPEEE part of the draft on the SER, and it talks about
that it is an inadequate seismic margin at some point.
MR. ARCHITZEL: Well, I guess that is
where you consider, and Donnie maybe could talk a
little bit to those numbers that you heard some about
yesterday, and the impact is not tremendously safety
significant of those future modifications.
CHAIRMAN WALLIS: It may not be safety
significant, but are they meeting the regulations
then, in terms of --
MR. ARCHITZEL: Well, let me just say that
for the current regulations -- and Donnie can talk
about the safety aspects of it, but for the current
regulations and with the seismic makeup that they
have, the isolation condenser, which would last now
and which would last before, 20 minutes approximately.
They are keeping that power level just
like the bypass valves, and they have got a set power
level, and it is a fraction of the existing power
level when it uprates, and so for 20 minutes they have
a make-up capacity that is seismic.
In addition to that, they have the
containment, and they have got the ability for a day
of containment. But the remainder of the seismic
capability to make up to the isolation condenser, they
have diverse sources.
And the diverse sources have some seismic
rigidity, but they are not safety related. You
wouldn't credit them an existing plant today. And we
have looked at some of the seismic statements. There
is one statement in the SEP that the far water system
was qualifiable.
MR. BAILEY: I think we are talking two
different things here, in terms of the low rigidity
that is discussed in the safety evaluation, and I
don't believe that that applies here. Can you give an
--
CHAIRMAN WALLIS: I am referring to this
.909G.24G.
MR. BAILEY: That is not really the issue
we are talking about for the ultimate heat sink.
CHAIRMAN WALLIS: No, it's not.
MR. BAILEY: For the ultimate heat sink
that the staff review is still ongoing, we are trying
to make sure that we understand all of the scenarios,
and all of the available water, and --
CHAIRMAN WALLIS: And that is a different
issue.
MR. HARRISON: This is Donnie Harrison
from the PRA branch, and the reference you are making
to the .09G HCLPF value is a reference out of the
IPEEE for Quad Cities.
CHAIRMAN WALLIS: Right.
MR. HARRISON: And it was recognizing that
that was, if you will, an unacceptably low seismic
capacity for a plant. At that time the licensee was
still in the process of making modifications, and most
of that was I believe Cable Tray and Anchorage.
And since that time I think at Quad
Cities, they are going to complete all their
modifications by the next outage, the completion of
the next outage for each of those two plants.
At that time the concern that the staff
was raising was there is not going to be a
reevaluation to see where the plant is. So the staff
used some numbers from Dresden, partly because the
Dresden -- well, we had the information on Dresden,
and the seismic hazard at Dresden is actually a little
higher than Quad.
So we felt comfortable as just being a
perspective of where the risk was for the .09G plant,
as opposed to going up to, let's say, your design
basis at 1202.4 from a HCLFP value.
And that was provided mainly to raise the
issue and to get a risk perspective of where the plant
was.
CHAIRMAN WALLIS: Is there going to be a
presentation from the staff on the risk perspectives?
MR. HARRISON: We can at any time you
want, yeah.
CHAIRMAN WALLIS: And that is where we
could revisit this seismic margin issue then perhaps.
MR. HARRISON: Sure.
CHAIRMAN WALLIS: So we will have that
again later in the morning, or timing willing, I
guess.
MR. ARCHITZEL: We will do that after the
break. And we can work out the order of presentation
after the break.
CHAIRMAN WALLIS: And we are approaching
the break as we approach the end of this presentation.
MR. ARCHITZEL: Well, I think that is
about it for ultimate heat sink. Part of the issue
also is whether the calculations were conservative or
not, or formalized, and those issues are still being
considered.
DR. SCHROCK: And that issue is limited to
the Dresden?
MR. ARCHITZEL: That's correct.
DR. FORD: And the feed water issues and
corrosion, that will come in later?
MR. ARCHITZEL: Yes. There is something
there on feed water, and about flushing out and how
the system changed, which was not in the application.
And getting additional information on the logic behind
running the pumps and saving the plan, and the plant
availability on how you run it, and where the suction
trips come in.
And actually trying to maintain the plant
on line was the focus of my review in the feed water
area. And the next slide.
CHAIRMAN WALLIS: This is the last one.
MR. ARCHITZEL: That's it. And the last
one was just going over the -- well, it is sort of an
open listing of areas that we reviewed, and if you had
questions, I could go into more. But if you don't
have questions, then -- you know.
CHAIRMAN WALLIS: Are we ready for a break
now? Are there any questions from members of the
committee?
MR. HANNON: Excuse me, but this is John
Hannon. I wanted to make sure that one of the points
that Ralph made is clear, because it relates back to
one of your concerns on the Duane Arnold review, and
John Zalinski asked me to follow up on that.
One of your points was that the staff
should develop criteria for when independent
assessments should be performed to compliment our
reviews of the applicant's submittal.
And this is one case where we did it on an
ad hoc basis. We sent Ralph to the site to do some
independent verification of the calculations that they
had done for the ultimate heat sink.
And the point that I wanted to make is
that we do do that on an ad hoc basis when it appears
to be appropriate. And this is a case where we
thought it would be appropriate for us to do it.
MR. ARCHITZEL: And also when I went to
the site also, you looked at the calculations for the
net positive suction head that the licensee had done.
So it was two different areas where we examined,
including that.
CHAIRMAN WALLIS: Thank you. So are we
ready for a break? So we will take a break until 25
until 11:00, a 15 minute break; and after the break my
colleague, Jack Sieber, is going to Chair, and I am
going to turn the Chair over to him.
I would ask my colleagues to send me
comments on this whole issue so I can prepare a letter
for the full committee.
(Whereupon, the meeting was recessed at
10:19 a.m., and resumed at 10:36 a.m.)
MR. SIEBER: I would like to call the
meeting to order. In looking at the agenda, we have
on the last page a response to ACRS questions, which
I think we should go through at this time.
And then we had some additional questions
on source term in the PRA, and so we can deal with
those at the staff's convenience. You can arrange
however you want to give the remaining presentations.
MR. BAILEY: We wanted to make a small
change in the agenda to address your request for a PRA
presentation.
MR. SIEBER: Okay.
MR. BAILEY: Donnie Harrison will present
his PRA analysis, and if this is all right with you,
then we would return to the responses to ACRS
questions portion.
MR. SIEBER: Okay. That's fine.
MR. BAILEY: And for clarification, we did
not get somebody or we were not able to get somebody
here to answer the questions related to the
radiological analysis.
MR. SIEBER: Okay.
MR. BAILEY: So if there are questions or
information you would like us to bring to the full
committee, we can offer you that.
DR. KRESS: I think those were mostly
clarification questions that I had, and I can dig in
to the stuff we have and get them out.
MR. BOEHNERT: So why don't you stand by
and we will let you know if we want something in
follow-up on that.
MR. BAILEY: All right. Very well.
MR. SIEBER: Okay. Why don't we begin.
MR. HARRISON: Good morning. My name is
Donnie Harrison, and I did the PRA portion of the
review of the power uprate. And these slides are just
back up information in response to your questions.
MR. BOEHNERT: We will need copies of
these.
MR. HARRISON: We will walk you through
it. If we could just move on to the next slide.
Basically, the information that we received from the
licensee is provided on this slide, as well as what
the staff used in its review.
We have the original submittal by the
licensee, which was just a couple of paragraphs if I
remember correctly. That was supplemented in about
the February time frame to address the key areas of
review that the staff typically looks at in the risk
area.
We then had a series of -- one major round
of RAIs with a series of clarifications and meetings
and such, and conversations on, and again this covers
the areas of internal events, external events,
shutdown operations, and then also just an area of PRA
quality, and does the plant reflect the as-built as
operated facilities.
The staff review looked at the licensee
provided information. We also looked at other areas.
For example, much of the external events questions
from the staff were derived from the Ses that were
written on the IPEEEs. We also pursued areas that
maybe the SE called out on the IPE.
DR. KRESS: And how exactly did you assess
the quality of the PRA?
MR. HARRISON: The quality of the PRA was
done in a couple of different ways. One is in July,
at the end of July, we actually -- two members of the
staff took a trip down to the Exelon facility to look
at their maintenance procedures and processes, to see
how Exelon actually ensures for themselves that their
models are up to date to ensure that the models
actually reflect significant changes to the facilities
that go on throughout a period of time.
They did -- and I will return Dr.
Burchill's compliment. They did an excellent job of
providing us information, and providing us a whole
series of their PRA materials, their procedures. We
understand that it is an evolving process, and it is
getting better all the time.
DR. KRESS: Has their PRA undergone the
industry peer review process?
MR. HARRISON: Both PRAs have undergone
that. Dresden went through it twice, and if you talk
to Dr. Burchill, he will say the first time was
probably premature for them to go through.
And they learned a lot of lessons and
reflected that in the Quad Cities and in the revision
to the Dresden PRA. So both events were both received
by March, and with their evaluation criteria, all of
them were -- all of the elements were at a high level
that could be used in a risk informed submittal
supporting deterministic information.
DR. SHACK: Was that the owners' group one
or the NEI? I mean, could we assign a Level-3 to this
thing? I mean, was there a number? I am not sure
whether the owner's group gives you that.
MR. SIEBER: The BWR owners group.
MR. HARRISON: They assign a number for
each of the 11 elements. For 10 of the elements, they
received a three; and for the 11th one they received
a four. So, higher is better than lower. So it was
a 3-4.
MR. BOEHNERT: Out of what?
MR. HARRISON: Out of four. That is a
good question. So, yes, the staff actually spent some
time, a few days, at the facility just to look at the
process. We looked at their -- they have a software
program that is kind of like an XL spreadsheet that
they track the modifications going on at the plant.
They evaluate those modifications to see
if they need to do an update immediately of the PRA,
or if it is something that they can wait until their
next periodic update.
Today, they have never had anything rise
to the level that requires that immediate update. One
of the things that the staff noted in its draft SE
write-up was given all of the changes going on with
the plant with this power uprate, and things in
parallel with this power uprate, the staff would
probably recommend doing an update on these
PRAs just to make sure that everyone is reading from
the same sheet of music.
But again that is more of a statement of
what the staff would recommend, and it is not a
required thing.
MR. SIEBER: If I look at the Section 10
of the safety evaluation, I see a lot of places -- and
I guess I have both Dresden and Quad Cities here --
where a statement was made that the delta-risk was
insignificant.
Does that mean that they actually modeled
the changes in the PRA and then looked at the numbers,
or does it mean that in the PRA the issue wasn't even
modeled at all?
MR. HARRISON: What I would say is that
there is a couple of things that the licensee did.
There were places where they put something in the
model and recalculated, and reran the model.
There is places where they used a
simplified model, where they were making the design of
the -- let's say the recirc run back circuit, and that
was in design at the same time they were doing their
PRA evaluation.
So they put in a simple model and ran that
through and saw what the impact was. Other cases --
and typically in response to the staff's RAIs, they
may provide us a calculation that says that the loss
of off-site power fast transfer is a new event that we
are going to evaluate.
And that we will just give you the
calculation to show you that the number is 10 to the
minus 10, or that the loss of off-site power
initiating event frequency would have been increased
by 2 times 10 to the minus 6, but it is a very simple
calculation.
So there is a smattering of different
approaches, depending on what the issue was, and how
we are dealing with it.
MR. SIEBER: Is it possible to pick that
out of the safety evaluation report on which method
they used when they were rerunning the model, or --
MR. HARRISON: I think I pointed out in
the write-up where they used simplified models or
simplistic calculations. I tried to make it clear
-- and that is where after going into each of those
sections the staff made a conclusion that it was using
a simplistic model.
If it had been a risk-informed submittal,
we might have sought for the licensee to confirm that
the design and the simple model either match, or the
simple model actually bounds it for sure.
So I think that would come out. We don't
necessarily go through and say here is all the
modeling changes that they did.
MR. SIEBER: Right. Well, I think that
would be too extensive, and would make this too long.
MR. HARRISON: Right. As it is, for a
section that is supposed to be an insight section, it
is still 20 pages long.
MR. SIEBER: Right.
MR. HARRISON: I hope that there is a lot
of insights.
MR. SIEBER: Okay. Thank you.
MR. HARRISON: We can move on, and the
next few slides are just going to repeat really what
Dr. Burchill mentioned yesterday, with maybe a
different slant on it from the staff's perspective.
They evaluated the key areas, and in the
initiating events area, component reliability, success
criteria, and operator actions. They addressed all
those areas.
There were some impacts pretty much
identified either by the staff or by the licensee in
each area. Again, as you mentioned, each area seemed
to have -- we are talking a percent here or two
percent there change in CDF.
We weren't seeing any major changes. The
next result is that there is -- and I think yesterday
that you saw Exelon had a CDF delta increase of 9
percent, and I listed 8 percent.
Maybe we count different. I have probably got more of
an error in the way that I added them.
Quad Cities is looking at a five percent,
and those are very small risk increases. The LERF
numbers again are 10 percent at Dresden, and 4 percent
at Quad Cities.
The difference between Dresden and Quad
Cities, I would probably argue, is mostly because the
base CDF and base LERF numbers at Quad Cities are
about twice as high as they are at Dresden, and
therefore, the change in risk is half at Quad Cities.
DR. KRESS: So the actual deltas were
about the same?
MR. HARRISON: Yes, for the most part.
The numerical number would be about the same. Again,
we would just point out that there were simple models
and simplistic calculations performed, as well as on
the transformers, and there was some question on the
switch gear and the breakers.
And there were some tests that the
licensee stated that they were going to perform to
show that they were acceptable, and they might have to
make some field modifications to make that acceptable.
It wasn't clear to me that those tests had
been completed and that the modifications had actually
been implemented. So that was to recognize that there
was some uncertainty there.
And then on the thermal hydraulic area,
the staff recognizes that they did an analysis of what
their typical thermal level will be, and not what
their licensed thermal level would be, which means
that they did the thermal hydraulics runs using MAP
about two percent below what the licensed level is.
And the staff recognizes that puts us into
a little bit of an uncertainty area as far as success
criteria and operator action time. But again we are
only talking about two percent in a 17 percent uprate,
and we don't see that as being something that would
trip us into a concern.
DR. SCHROCK: Did they have some reason
for doing that?
MR. HARRISON: The rationale again is that
the PRA is supposed to reflect more of your realistic
operations, and the plant will typically be operating
at a lower thermal limit to achieve the same
electrical output, except for I think during the
summer months.
And there might be periods during the
summer where they actually have to increase that to
get that output. So, yes, it was mostly just to get
a realistic perspective.
Again, the staff would have preferred that
they do it at the license level to just take any doubt
out. So that was just to recognize that that was the
condition.
DR. KRESS: Did they do any uncertainty
analysis?
MR. HARRISON: No. They did do
sensitivity analysis I think in the past, and I think
you heard some of that yesterday. But there were no,
if you will, sensitivity calculations done at a higher
thermal limit, or at least not provided to the staff
to verify that they were acceptable in that area.
DR. FORD: To somebody in the public, the
use of your words, use of simplified models and
simplistic calculations, is somewhat negative. Could
they have used a more professional approach?
MR. HARRISON: This is not questioning
their professionalism. This is more of just
recognizing -- and maybe I need to change my words,
but recognize the fact that in some cases they were
designing a circuit, or designing a feature at the
same time that they were modeling that feature.
And Exelon took the approach of trying to
bound that, and they bounded it by using simple
models.
DR. FORD: But that --
DR. SHACK: Simplified bounding.
MR. HARRISON: Simplified bounding, or
simplified conservative models. Again, there is not
a confirmation at the end to ensure that the circuit
that they actually did install is bound. I mean,
there is uncertainty there.
And again if this had been a risk informed
scenario, we would probably be chasing down that
confirmatory analysis to make sure that what was
installed is truly bounded by what they actually
analyzed.
Typically, an example would be that on the
reactor recirculation pump run back feature. They
increased their turbine trip initiating event
frequency by a few percent, and ran it through their
model, and did not take credit for at Dresden the fact
that the recirc pump would keep you from tripping.
So in that sense the staff then has
confidence that their analysis should have bound the
impact.
DR. FORD: The only reason why I am
bringing up this question is that this is open to the
public, and someone in the public could construe that
as being a simple, but inadequate, analysis, and that
is not your meaning.
MR. HARRISON: Right. That is not my
meaning. I am meaning to say that it is a -- if you
want to use a conservative -- well, I don't like using
bounding in PRA language, but that seems like an
oxymoron.
It is a conservative approach to trying to
address the condition you are in, where you are
designing a component while you are modeling it at the
same time. So it just recognizes that fact. If we
could move to the next slide.
We also looked at external events and
shutdown operations and PRA quality, and we have
already touched a little bit on the last one. The
staff spent quite a bit of time on the external events
portion, primarily in the area of seismic outliers.
The IPEEE for both of these stations
identified outliers in the seismic margins analysis,
and we aggressive pursued those with the licensee.
And especially for the seismic dam failure, which I
think you have heard about now at least partially
twice.
We saw after addressing those scenarios
specifically from a risk specific to see where we
were. At Dresden, the rest of the plant meets its
seismic margins analysis criteria for a .3G focus
scope plant.
We didn't pursue those things that were
already at that level. We wanted to see where the
outliers were. The results of that were that we had
some -- I think if you add it all up on the seismic
side, it comes out just a little below 10 to the minus
5 as the risk.
And that includes not just the outliers,
but also taking into account the fact that you could
lose the isolation condenser seismically as well. And
if you add that on, you get it right around 10 to the
minus 5 as a CDF value.
And the isolation condenser does meet the
.3G margins analysis, but I put that in just as a
perspective. On the fire analysis, they indicated
that there was a small risk increase that is mostly
due to operator actions.
However, again, using Dresden as an
example, their methodology is what I would call a
progressive screening criteria type methodology, where
if you get an acceptable answer, you stop analyzing.
MR. SIEBER: That was strictly a control
room fire.
MR. HARRISON: That was a control room
fire, and they took a 50 percent chance of going to
core damage if I lose the control room. So any kind
of operator actions that changed by 5, 10, 15 percent,
are never going to raise to the level that would
offset that high of a conditional core damage
probability, unless you find out that you just can't
do it. That would be about the only way to get there.
I think we have talked in the past about
shutdown operations for BWRs. Typically, you have
long times to boil, and it is not a concern as much as
it would be for, say, a PWR.
MR. SIEBER: They did not have a shutdown
PRA?
MR. HARRISON: They do not have a shutdown
PRA. They do have a risk management program called
ORAM.
MR. SIEBER: Yes, and I am not sure that
you get a quantitative number out of that. You get a
color, and it really just looks at multiple paths.
MR. HARRISON: Right, success paths.
MR. SIEBER: So I am not exactly sure how
you can draw a conclusion that says negatively small
increase in risk from using an ORAM as a tool.
MR. HARRISON: Right. We are not basing
our conclusion there on a model. It is more of a
qualitative conclusion saying operator actions will be
reduced by some amount because of the higher decay
heat.
However, they do have a risk management
process in place, and I think there was a discussion
yesterday about their backup cooling systems, and that
whole topic becomes moot because of their short
refueling cycles, and refueling outages.
If you are only out for 20 days and it
takes you 26 days of cool down to get to a point where
you could use a pump, it becomes a non-issue. That
pump is not available.
So given that, we are just acknowledging
the fact that there would be some impact, but we don't
believe that it would be significant.
MR. SIEBER: Okay. Now, I do not recall
anyplace in the safety evaluation where the idea that
the refuelings are probably going to be a day or so
longer because of the higher decay heat level. Was
that evaluated at all, and will that have an impact on
shutdown risk?
MR. HARRISON: I would answer that in two
ways. No, I did not evaluate that, but off the top of
my head, if you are -- and again if I am not going to
get -- well, yes, there would be some increased risk,
because you are operating another day out there.
MR. SIEBER: Right.
MR. HARRISON: Again, the backup systems
that would be available are marginal at that point
anyway. So you would be just progressing your risk
management just a little further.
You could also argue that backwards and
say then if I can shorten my outage by a day or two I
save risk. Given the drive of the industry, the
shorter they go -- it is an economics question.
The licensee is going to drive for a short
outage, and if he can shorten that outage, he will.
So there is no way to quantify that type of an answer.
On PRA quality, like I said before, they
did go through the owners group peer certification
process. The last two bullets just point out the fact
that with simple models and simplistic calculations,
you don't necessarily have a hundred percent
confidence that everything is precise.
When you are in PRA, nothing is precise.
So there is a little bit of -- I would like to make me
feel a little if they did a few extra things, but they
don't think -- I don't think that would be -- it
wouldn't change the answers and that is the bottom
line.
The last bullet really just recognizes
that in the IPEEE the plant too credit for conditions
that do not exist, and they are in the process of
making modifications to make that fit.
And as part of our review, I believe they
conducted their -- they had a seismic condition with
the dam failure, and they had assumed that the LOCA
conditions were fine.
And as part of our questioning, I think
they went back and did the study that they had
committed to in the IPEEE a few years ago, and the
results of that were that they do need to add a means
of -- an alternate means of -- or a seismically
qualified means of getting a containment cooling
service water path in.
MR. SIEBER: But those modifications were
just hangers in supports, right?
MR. HARRISON: Those modifications for
Quad Cities were mostly anchorage. For Dresden, it is
not. For Dresden, the modifications that we are
talking about are the portable pumps, the hoses, the
connections, being able to route the lines through,
and drop the pumps in, and get the water where you
need it.
MR. SIEBER: Right.
MR. HARRISON: That is how they are going
to address the seismic issues at Dresden. It is not
going to be a hard-wired implant system. The next
slide just goes over what we concluded through our
review.
Again, this recognizes that we identified
a number of issues, and the licensee -- the
methodology that they used, and the simple
calculations, this just kind of goes over that again.
With the last couple of bullets just
recognizing that they had been risk informed, we would
probably require some type of confirmation that the
simple models and the simple calculations truly are
bounding the conditions.
And to actually analyze the procedures
that they are creating for like load shedding in a
transformer, to verify that their screening human
error probability really is screening, and there is
not something out there that might be higher.
The last bullet there just says, however,
the submittal is not risk informed. They are meeting
their deterministic requirements, and the information
that we have does not make us question the adequate
protection of the plant.
So with that conclusion, we pass it back
to the deterministic folks to address the issues in
their areas, and that's all that I had on the risk
assessment piece of it. Are there any questions?
MR. SIEBER: Does anyone have any
questions? If not, thank you very much.
DR. FORD: Again -- well, I'm sorry, but
just about the last thing, when you say that submittal
is not risk-informed. It doesn't have to be risk-
informed does it by the regulations?
MR. HARRISON: No.
DR. FORD: The deterministic requirements,
are they adequate?
MR. HARRISON: That is not a judgment for
me to make. That is a judgment for each of the
deterministic branches that do their reviews
collectively and come together as a basis for the
final solution.
MR. SIEBER: Actually, the submittal is
risk-informed, and the decision making was not.
MR. HARRISON: Was not, yes. And we may
be talking about technical questions, but risk
information is provided, but in the terminology of
risk informed, it is not risk informed.
MR. SIEBER: Right.
MR. HARRISON: And again we kind of talked
past ourselves.
MR. RUBIN: This is Mark Rubin from the
staff. It was not submitted as a risk informed
licensing action.
DR. FORD: Well, the reason that I am
bringing it up is that it might sound nitpicking, but
again I come to this public perception being that it
is out there, and that bold statement of not risk
informed.
On the face of it, it would sound
negative. It is not negative. It just is not
required. It is a factual statement.
MR. HARRISON: And it is a factual
statement in that it just recognizes that the LTAR
requires them to provide risk information. We review
that information, and it is not conveying that there
is something wrong with the submittal the way it is.
I don't want to convey that. Thank you.
MR. BOEHNERT: Again, I would like to get
copies of your slides.
MR. HARRISON: I will make them now and
give them to you.
MR. BOEHNERT: Thank you very much.
MR. ROSSBACH: Okay. Next in our
presentation -- well, actually, we didn't have further
presentations prepared, but we do have reviewers
available to answer questions in these other areas.
The first one we have listed is material
degradation issues, and it is because in your letter
responding to Duane Arnold, you pointed out the
significance of flow assisted corrosion and irradiated
stress corrosion cracking to the evaluations.
Although in yesterday's licensee's
presentation, you seemed to be satisfied with that,
but we do have reviewers here if there are questions
in these areas.
MR. SIEBER: Do we have any questions? I
recall someone suggesting that they would like further
information on seismic.
DR. FORD: As an independent person with
a conflict of interest, I have no problems at all with
the materials degradation. I was more interested in
just the process by which you evaluated those
potential degradation modes. And I don't know if this
is the forum to ask those questions. For instance --
MR. ROSSBACH: Would you like us to
address the process?
DR. FORD: -- in the flow area, a lot
depends on the CHECWORKs and its qualification, et
cetera. Did you perform or did you oversee that
qualification of the use of CHECWORKs?
MR. PARCZEWSKI: Yes, we did look at it,
you know, because this is the only way --
MR. BOEHNERT: Could you identify yourself
for the record, Kris?
DR. FORD: Kris Parczewski, from Material
Chemical Engineering Branch, NRR. You need to look at
the other CHECWORKs prediction, and we were satisfied
that there were relatively low, and what is most
important is that the licensee has the program,
ongoing program.
And you can always verify, and if you are
going to verify the prediction, then he will be able
to project it in the future. So this will be a well
controlled process for the licensee.
And I find that it is not really a very
significant change due to a power uprate. The highest
one is obviously in the feed water because of the high
velocity change.
The other components are considerably
smaller changes, and so it is not very significant
really.
DR. FORD: There are a few other minor
questions in the area of flow induced vibrations, for
instance, and in the new design of putting in a steam
dryer. Were those reviewed?
MR. ROSSBACH: That would be the
mechanical engineering branch.
DR. FORD: And the transfer of those loads
to the support brackets, and the effect they may have
on stress corrosion cracking in that area which is not
protected by Noble Chem.
MR. MANOLY: My name is Ken Manoly, and I
am a section chief in the Mechanic Branch, and I would
like to address your questions on the steam dryers.
I have one slide to maybe give you a summary of what
are the conclusions in that area.
We noticed that you were interested in the
topic last time and that's why we gave it more of a
focused attention this time, and pretty much the
conclusions from both plant reviews, both from Dresden
and Quad, were pretty much the same.
That there is no increase in the actual
pressure of the temperature, and the core flow is not
much increased. The only increase is in the steam
flow, and to get into flow induced vibration, maybe I
can get into detail if you want to get into that.
The key thing to emphasize in the
submittal is that the component is not faulty, but
they still want to ensure its integrity for the fault
condition, which is a main steam line break.
And for that they evaluate the stresses to
the ASME NG Section 3, which is fairly new. It came
way after the plant was built. The stresses all meet
the code limits.
DR. FORD: Just to interrupt you and to
save time, I can see all those factual things there.
What is not covered is when we had the Duane Arnold
review, they stated that there would be a transference
of those stresses to the dryer support brackets welded
to the RPV.
MR. MANOLY: Right.
DR. FORD: I assume the same would apply
in this situation, too.
MR. MANOLY: That's true.
DR. FORD: Was there an analysis done on
your behalf of the impact that it might have on
environmentally specific cracking on that welded
bracket?
MR. MANOLY: Well, we didn't do that
analysis. We responded to questions in REIs about the
adequacy of the anchorages.
DR. FORD: Good.
MR. MANOLY: And they said to evaluate the
anchorages, and they were fine.
DR. FORD: And how would that be managed,
by the inspection process? Would the dryer brackets
also be inspected by BWRVIP-06?
MR. MANOLY: Yes. I think with every
refueling that the dryers are inspected and removed.
DR. FORD: And the brackets, the brackets
are also inspected?
MR. MANOLY: I am not certain, but I can
get back to you on that. I am not quite so certain
about the brackets.
DR. FORD: The reason that I keep pushing
this is because if they fail, then the whole thing
falls, or potentially falls.
MR. MANOLY: Right. That would be a very
easy thing to verify, the statement in the VIP,
because we have the VIP SERs already written up.
DR. FORD: I am moving along here, Jack,
and I am just trying to get a feeling of the
assessment that went through. On the cracking issues,
the cracking of the main structural welds in the
reactor, in the core shroud, for instance, H-4 and H-
3, H-6 welds, was there any analysis done on how the
increase in flux of 17 percent, how that is going to
affect the cracking of those components?
MR. MANOLY: I will have to defer that to
the materials branch.
MR. CARPENTER: This is Gene Carpenter
with the materials and chemical engineering branch.
Basically, what we have done with the core shroud or
other internals is that we have asked licensees to
take a look at just what their fluence levels are.
And when they get to a certain threshold
limit, that drops them into a higher crack growth rate
regime, and at that time they have an increased amount
of inspection that is required.
DR. FORD: Okay. Is the current -- I have
forgotten the VIP numbers. There are so many of them.
But are those fluence values that might be accrued in
the next -- since they are going for license renewal
in the next 10 years, are they likely to get into
fluence regions where they might be a marked increment
in cracking susceptibility?
MR. CARPENTER: Some licensees have
already reached the 5E to the 20th neutrons per square
centimeter fluence value, which is what we consider
the threshold value.
And as these reactors age, they obviously
have more internals coming to that point. Now, when
I say some licensees, what I am saying is that is at
the core shroud. We are not talking about the vessel.
DR. FORD: I asked a question the other
day about the delta-P across the access hole covers,
and I presume there will be an increased delta-P, and
they mentioned that they had a redesign of the access
hole covers. Was that analyzed or examined by the
staff? Is there any increase in the cracking of --
and I am not too sure what the redesign is. Are they
still welded designs or bolted designs for the access
hole covers?
MR. MANOLY: I cannot respond to the
question right now. I need to get back to you to see
what information we have on it.
DR. FORD: It is not a major safety issue
I don't believe. Thank you. Those are the only major
questions that I had. I just wanted to understand
what the process was.
MR. SIEBER: Do we have anything else that
the staff would like to present?
MR. ROSSBACH: Earlier, we did have one
question from the ACRS dealing with the pipe supports
modifications, and if you want any information on
that, I can tell you that some main steam and TORUS
attached piping systems were determined to require
support modifications to bring the piping within code
level stress limits.
Now, some TORUS attached piping support
MODS are required due to higher power uprate thermal
loads, and some main steam support modifications are
required as a result of applying the turbine stop
valve closure loads. If you want any elaboration on
that the staff is here.
MR. SIEBER: Well, that is basically in
the SER, almost verbatim. So does anyone have any
questions? Okay. I would like to -- I think we are
done now, and so I would like to thank the staff for
their presentation, and also Exelon and G.E.
I think it was very informative, and very
knowledgeable, and you certainly brought enough people
with you to cover anything and everything that we
could have asked.
What I would like to do now though is
spend some time with the members so that we can get an
idea of what members comments are at this point so
that we can provide those comments to Dr. Wallis while
he begins drafting a letter.
I presume that the staff wants a letter
from us at their next full meeting, and so with that,
Dr. Shack, do you have any comments that you would
like to make?
DR. SHACK: No. I missed much of
yesterday's presentation and so I feel a little
restricted about making comments and so I will just
defer to the members who attended the full session.
MR. SIEBER: Okay. Dr. Ford.
DR. FORD: There seems to me to be five
kind of areas in the materials degradation area that
needed or should have been addressed, and in large
part were.
And those include the flow induced
vibration, and the flow assisted corrosion, the
embrittlement of the pressure vessel, and the whole
question of cracking of the main structural welds in
the reactor, all of which could conceivably be
affected one way or the other.
I think they all have been addressed both
by the licensee and analysis done by the staff of all
of those. And I don't think that with the ACRS that
they should be discussed in any detail. I don't think
there is a major problem that cannot be managed with
the management programs that exist.
It would be an idea just to put those up
as I mentioned yesterday in just one page just to
record that they have been analyzed. And one area
that wasn't discussed yesterday was a question of
Nitrogen-16, which would depend very much on the
adherence of Noble Chem with the higher flow rates.
I personally don't think it is a problem,
but it is something that should be addressed
somewhere.
MR. BAILEY: Would you like to discuss
that now?
DR. FORD: Well, I am just asking has it
really been looked at and are people satisfied. Can
it be managed.
MR. CARPENTER: This is Gene Carpenter
again with materials and chemical engineering branch.
We have been looking quite closely at the chemistry
that is involved with the BWR internals, and
specifically hydrogen water chemistry and the Noble
Chem issues.
Obviously if you have an increase in N-16,
you are going to have an increase in shine, and so it
is a very easy problem to ascertain that you have.
We have also asked the industry to go back
and have a monitoring program to ensure that the NMCA
is appropriately applied, and that it is maintained
throughout the operating cycles so that they do need
to know when they are going to reapply it to maintain
effectiveness.
We have also asked them to have an
effective hydrogen water chemistry program in place,
and we have been making some great strides towards
that. So the N-16 problem, I think, is under control.
MR. SIEBER: Well, that was actually
discussed in the safety evaluation report and the
issues were does this provide additional safety to
workers, and does it affect equipment qualification,
and things of this nature.
And obviously N-16 without some additional
offsetting treatment is proportional to the change in
power, and that the safety evaluation radiological
evaluation indicated that the increase was negligible
as far as to workers and potential dose off-site.
And in equipment qualifications space, I
think they had to run or get additional data on
Rosemont transmitters. And there were some
transmitters that were installed that weren't EQ, and
that had to be changed out to make them EQ.
And so I think the N-16 issue was pretty well covered.
MR. CARPENTER: Yes.
MR. SIEBER: And as far as fluence is
concerned, it seems to me that the Dresden and Quad
Cities reactor vessels are fairly large compared to
the core that is inside them. So there is some
absorption that takes place, which means that the
fluence does go up by 17 percent at the vessel wall or
the shroud.
And so the impact isn't as great as one
might presume, and also in that type of vessel there
are other plants that operate with higher power
levels, and so that doesn't make Dresden or Quad
Cities any different than those plants, at least in my
way of reasoning.
DR. FORD: That is my point.
DR. SHACK: Just to come back to Peter's
question, and again it is a question for Gene. The
way the hydrogen water chemistry will run under the
Noble Chem is that they may not be continuously
modeling potential.
And so they will probably be putting in a
fixed amount of hydrogen, which means that if they
lost their Noble metal coating, what would really
happen would be their susceptibility to cracking would
go up for a portion of the cycle.
MR. CARPENTER: That is correct.
DR. SHACK: And then with an N-16 concern,
their susceptibility would increase presumably until
the end of the cycle and they found out that they had
somehow mis-estimated the potential wear rate for the
Noble Chem. Isn't that the way it would work
basically?
MR. CARPENTER: That is the way that it
would work, and we have also asked the industry to go
back and have a way to monitor during the operation
that they do have an effective hydrogen water
chemistry in place at least 80 percent of the time,
which we believe is sufficient to ensure the crack
growth rate will maintain itself at a sufficiently low
level.
MR. SIEBER: Okay. I guess from my
standpoint, I am not -- I need to study some more
about the unit auxiliary transformer and the RAT to
assure myself in my mind that what has been done is
okay from an electrical standpoint and I will do that
on my own.
I did have another question where I would
note that a number of set points have been changed,
and the safety evaluation, the draft safety evaluation
discusses the set point change methodology, which I
presume originally came from Commonwealth Edison?
MR. BAILEY: Actually, it was done more
recently. We just approved a new revision or a new
version of their set point methodology with the ITS or
improved tech specs, which was granted to these two
plants this March.
MR. SIEBER: Since March?
MR. BAILEY: Yes, since March.
MR. SIEBER: And do you have a safety
evaluation specifically for subpoint methodology?
MR. BAILEY: It is part of the approved
tech spec safety evaluation.
MR. SIEBER: Which is probably huge,
right?
MR. BAILEY: It is big.
MR. SIEBER: Is there a chance that
somebody could send me the pages that relate to the
set point methodology?
MR. BAILEY: You would like the pages
related to the set point methodology?
MR. SIEBER: Right, because you referenced
them, and I remember Commonwealth Edison set point
methodology from a few years back, and so I would like
to assure myself that what they are doing now is in
conformance with the way that the industry is doing
that.
MR. BAILEY: Okay. It was done as part of
their transition to a 24-month fuel cycle.
MR. SIEBER: Okay. But just send me the
pages, as opposed to sending me the whole thing,
because my office is now full of papers. Dr. Kress.
DR. KRESS: One of my points that I would
like to have a little more help from the staff was how
they were able to assure themselves that the LOCA
codes to meet the figures of merit, and Appendix K
requirements were still valid for flat flux, knowing
that the validation was based on 2D and 3D type tasks,
which did not have a flat flux.
I would like to know how they assured themselves
that the codes were still valid. The other thing that
I would be interested in is maybe a little more on
Virgil's point about the Origin code, and how they
assured themselves that it was used properly to get
the right inventory.
MR. SIEBER: Okay.
DR. KRESS: And I guess I would like to
see a little better explanation of why the MELLLA
curves were different, even though I understand that
there is good reason for them to be different. But
maybe a little explanation of why precisely they were
different.
MR. SIEBER: Okay.
MR. BAILEY: I understand at the break
that the licensee has looked at them again, and sees
only differences in the low flow region. Did you want
to --
MR. PAPPONE: I don't know where the
proper forum is to address that is, but we can address
that with the staff or with the ACRS afterwards, or at
any time.
MR. BAILEY: Okay.
MR. SIEBER: Well, I think if we are going
to discuss it, we ought to discuss it while we are in
formal session, as opposed to having a sidebar that is
not on the record.
MR. BAILEY: Dan, can you give a
description of what we learned about those curves.
MR. PAPPONE: This is Dan Pappone from
G.E. As I said yesterday, when we draw that MELLLA
line on the power flow map, we are using a generic
line for all the plants and all the product, and so
that licensing line does not change. The line on that
map for Dresden and Quad Cities, that line is the same
for that.
DR. SCHROCK: Say that one time again?
MR. PAPPONE: The line itself is the same.
It is following the same equation as was proposed for
the license.
MR. BAILEY: Are there scaling factors
that make the figures look different?
MR. PAPPONE: Where the point of confusion
is coming in --
DR. SCHROCK: Let me say that Point A has
numerical values in the little table in the set of 43
pressure, and 23 full.
MR. PAPPONE: Right.
DR. SCHROCK: And I don't have the other
one in front of me, but the numbers were more like 58
and something else.
MR. PAPPONE: Right. The difference
between the two flow maps is in the natural
circulation line, and we do have to investigate why we
have a difference in the two lines, and what the basis
for that is.
But that corner point, I can take the
equation for the rod line, which is a function of core
flow, and put in that core flow value, and calculate
the corresponding power value.
MR. BAILEY: And the points going down to,
but not including, this natural cert point, would also
be calculated from the same equation for both plants?
MR. PAPPONE: That's right. If you laid
a ruler on that line, you would see a slight curve.
If you would also take a look at each corresponding
core flow, that power value would be the same. It is
a piece that we need to go back and investigate for
the basis for the natural circulation line, and the
difference between the plants.
DR. SCHROCK: And so that is an item to be
followed up on prior ot the full committee meeting?
MR. PAPPONE: That's right. We don't have
that information.
DR. SCHROCK: But let me ask it another
way. I think the question that Graham followed up
with was that this line is in operation limits, and so
if during your maneuvers you approach that line, you
have to back off?
MR. PAPPONE: That's right.
DR. SCHROCK: The position of the line in
the vicinities, say, of core flow of 50 and minimal
power on the order of 60, is different on the two
presentations in the two SERs. So which of those is
it that --
MR. PAPPONE: Well, you may be seeing
different sizes of the plots if you put the two
together, and you may be looking at physical plot
scales, but the equation for that line is the same for
both.
DR. SCHROCK: I don't understand how the
equation can be the same and then when you use the
equation to plot a line, you get a different line.
MR. PAPPONE: That's what I am saying. If
I go to each one of those points along the line for a
given core flow for either unit, I get the same power.
It is just that the difference in those
two plotted lines, the natural circulation line, and
in one case it is minimum and in the other it is 32
percent, it is not quite the same.
So where those points that are identified
in the table, we are looking at different core flow
going into the calculation, and so we have a
corresponding different power. Does that make sense?
DR. SCHROCK: Not yet.
MR. PAPPONE: So the difference in failing
is the core flow.
MR. BAILEY: And what you are measuring is
in percent?
MR. PAPPONE: Absolutely.
MR. NIR: This is Israel Nir from G.E.
Let me help you. This is a quick mathematical
exercise. Look at the two maps and establish what is
the power level associated with 40 percent core flow,
and you will find that in both maps it is 58 or
approximately 58.
And I am just selecting one point, and
that should convince you that these two lines are
identical, except that one of them is extended further
relative to the other all the way to natural
circulation. But the same equation is used in the
definition of the two lines.
MR. PAPPONE: Right.
DR. SCHROCK: Does that explain the
differences in the position of Point A?
MR. PAPPONE: No, Point A is --
DR. SCHROCK: Point A is a different thing
in each case?
MR. PAPPONE: That's right. And that is
the piece where we have to go back and get the
explanation for why that natural circ curve is showing
differently. We have a similar situation where one
unit plotted that minimum speed line --
MR. NIR: Let me make another
clarification. As part of this effort, we redefined
the power level and the MELLLA boundary. Those are
indicated on the flow map. There are certain portions
of the power flow map that are not affected by power
uprates, and the introduction of MELLLA.
And those lines are the natural
circulation, the cavitation lines, and these are the
same or maintained the same as a power uprate. And
the differences that you observe are differences that
exist now. Those features that are new are identical.
DR. SCHROCK: So you believe there is a
difference in the natural circulation characteristics
of Quad Cities versus the Dresden plants?
MR. NIR: There is a difference in the
presentation and we need to get back with you as to
the reason.
MR. PAPPONE: That piece may tie back to
the historical source that was provided and that Jason
talked about earlier.
DR. SIEBER: Dr. Schrock, do you have any
additional comments that you would like to give us?
DR. SCHROCK: Well, first of all, the open
issues, and the testing question I find a little
puzzling. I thought that the authorities case was
that testing would be unnecessary sounded pretty
convincing.
It is still unclear to me what the G.E.
position was. I heard that G.E. a new submittal
related to this, and I guess we didn't hear very
clearly a position put forth from G.E. representatives
about that, and if they could comment further on that.
It is a little unclear to me on why the
staff is unable to address that position of G.E. and
the utility with regard to this issue. I don't know
what evidence is missing that is going to be
forthcoming in the making of that decision. So I just
find that whole thing a bit puzzling.
And I understand the revision done on
Duane Arnold, and that we are not to take these graphs
for Dresden and Quad Cities is being final either, but
it is not clear to me where that stands with regard to
the nature of the modifications that are going to be
made, and that there are very many weaknesses in these
SERs.
And over-reliance on such statements as
that the submittal is done in accordance with existing
approved codes and using existing codes, and therefore
the results must be accepted, and that seems to me to
be overly simplistic.
And I don't think you need a one inch
thick SER to relay that message if that is really what
the SER has to say. I found the SER in both of these
cases to be rather weak statements of how the staff
has come to the conclusion that the SERs should be
accepted.
That is not to say that I don't think that
they are acceptable. It looks to me like they are,
but I do think that there are many ways in which
things can be done with this sweep of codes that will
produce different results.
And put them in the hands of different
users, and they will come up with different results,
and guaranteed almost every time. So, again I have
not heard enough to convince me that the staff knows
that the codes are applied in the right way to get the
answers that justify saying that the thing is an
acceptable uprate. That's really all I have.
MR. SIEBER: Well, I think that will give
us some meat that we can work on over the next 10 days
or so.
MR. BOEHNERT: Yes. I think I will get
with Graham and we will come up with some agenda items
for the licensing.
MR. SIEBER: That will be very good.
Well, again, I would like to thank the staff, the
Exelon, and General Electric, for their presentations.
MR. ROSSBACH: Mr. Sieber, I would want to
address a little bit of information on the question on
the access hole cover that was raised.
MR. PARCZEWSKI: Dr. Ford, you asked a
question about the access hole cover, and we asked the
question in the RAI and we evaluated the new
replacements and the loads increased from 70 ksi to 80
ksi, but that is still way below their limit of
159psi.
DR. FORD: This is a bolted design?
MR. PARCZEWSKI: Yes.
MR. NIR: This is Israel Nir of G.E.
again. Just for the record, there was a couple of
times that you mentioned the G.E. position on the
large transient. Let me just remind the subcommittee
that we were here back in June of this year, and
provided you some background on the constant pressure
power uprate.
If you go back to the minutes you will
find that we provided you some information related to
Hatch on start up tests, and elevated power up to
roughly 114 percent. We also provided you some
background on large transient events related to
constant pressure.
And we will be happy to discuss it
further, and I think it will be needed to be in a
closed session and clarify our position.
DR. SCHROCK: So the reason that we didn't
hear any G.E. position in this meeting is that it was
an open meeting?
MR. NIR: That is the reason, yes, and I
cannot get into any details, but we fully support
Exelon's position.
DR. SCHROCK: All right.
MR. SIEBER: Are there any additional
comments or statements? Yes, sir?
MR. BAJWA: Just a closing comment on the
staff's presentation. I would like to thank you for
the opportunity to present our review of the Dresden
and Quad Cities extended power uprate.
The Commission has given a high priority
to these amendments. These are the first applications
of many that I am sure that we will see for power
uprates of this magnitude. I would like to emphasize
that the NRR staff has undertaken an extensive review
of these applications and for all areas affected by
the uprate have been reviewed and evaluated.
The staff has critically examined the
methodologies and their application of this power
uprate request, and the exception of the open item as
we have mentioned, and that were discussed today on
the testing issue.
And I would like to emphasize that these
applications are not risk-based applications, and the
evaluations which were conducted on the deterministic
evaluation analysis have demonstrated that the
proposed increased power level for Dresden and Quad
Cities units are acceptable and meets the regulatory
requirements.
This concludes the staff's presentation,
and if you have any questions, we would be glad to
answer them.
MR. SIEBER: Thank you very much, and I
think with that, it is a quarter-to-12, and so we have
met all of our goals, and so I will adjourn the
meeting.
(Whereupon, the meeting was concluded at
11:45 a.m.)
Page Last Reviewed/Updated Tuesday, August 16, 2016
Page Last Reviewed/Updated Tuesday, August 16, 2016