Thermal Hydraulic Phenomena - January 16, 2002
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: Wednesday, January 16, 2002
Work Order No.: NRC-177 Pages 1-19/187-193
NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers
1323 Rhode Island Avenue, N.W.
Washington, D.C. 20005
(202) 234-4433UNITED STATES OF AMERICA
NUCLEAR REGULATORY COMMISSION
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ADVISORY COMMITTEE ON REACTOR SAFEGUARDS
THERMAL-HYDRAULIC PHENOMENA SUBCOMMITTEE
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JANUARY 16, 2002
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The Subcommittee met at the Nuclear
Regulatory Commission, Two White Flint North, T2B3,
11545 Rockville Pike, at 1:00 p.m., Graham Wallis,
GRAHAM WALLIS, Chairman
PETER FORD, Member
MARIO BONACA, Member
THOMAS KRESS, Member
WILLIAM SHACK, Member
ACRS CONSULTANT PRESENT:
Introduction . . . . . . . . . . . . . . . . . . . 4
G. Wallis, ACRS
CPPU Topical Report. . . . . . . . . . . . . . . . 4
GE Nuclear Energy Presentation
Introduction . . . . . . . . . . . . . . . . 4
NRC Staff Presentation . . . . . . . . . . 187
CHAIRMAN WALLIS: The meeting will now
come to order.
This is a meeting of the ACRS Subcommittee
on Thermal Hydraulic Phenomena. I am Graham Wallis,
the Chairman of the Subcommittee.
Other ACRS members in attendance are Peter
Ford, Thomas Kress, and I think William Shack, but not
Mario Bonaca. The ACRS Consultant in attendance is
The purpose of this meeting is for the
Subcommittee to discuss the GE Nuclear Energy
Licensing Topical Report NEDC-33004-P, "Constant
Pressure Power Uprate," and to begin review of the
Framatome ANP-Richland S-RELAP5 realistic thermal-
hydraulic code version and its application to large-
break LOCA analyses. The Subcommittee will gather
information, analyze relevant issues and facts, and
formulate proposed positions and actions, as
appropriate, for deliberation by the full Committee.
Mr. Paul Boehnert is the Cognizant ACRS Staff Engineer
for this meeting.
The rules for participation in today's
meeting have been announced as part of the notice of
this meeting previously published in The Federal
Register on December 20, 2001.
Portions of the meeting will be closed to
the public, as necessary, to discuss information
considered proprietary to General Electric Nuclear
Energy and Framatome ANP-Richland.
A transcript is being kept, and the open
portions of this transcript will be made available as
stated in The Federal Register notice. It is
requested that speakers first identify themselves and
speak with sufficient clarity and volume so that they
can be readily heard.
We have received no written comments nor
requests for time to make oral statements from members
of the public.
We would now like to proceed with the
meeting. I will call upon Mr. Israel Nir of GE
Nuclear Energy to begin after my colleague, Dr. Ford,
makes a statement.
MEMBER FORD: I have a conflict of
interest on this afternoon's discussion since I am a
General Electric retiree.
CHAIRMAN WALLIS: Thank you.
MR. NIR: My name is Israel Nir,
representing General Electric, who will be presenting
today the GE BWR Constant Pressure Power Uprate
Earlier last year we submitted the
Constant Pressure Power Uprate Licensing Topical
Report for NRC review. We anticipate shortly that the
Draft Safety Evaluation will be issued, and we would
like to take this opportunity to provide you some
background information and facilitate your upcoming
review of this LTR.
Let's start with a short open session,
review briefly some of the past EPU briefing to the
ACRS, go over the key elements of the GE Power Uprate
Program, and provide you an update on the GE BWR Power
Uprating Implementation status.
The closed session will consist mainly of
fairly brief BWR overview, a brief discussion on the
CPPU/LTR approach, and then we are going to review
selected topics associated with the submittal.
GE, as of now, has extensive experience
with EPUs. EPUs are being implemented at --
CHAIRMAN WALLIS: You don't really have
experience with implementing, do you? You have
experience with preparing for and justifying?
MR. NIR: GE has extensive analysis
experience with EPU--
CHAIRMAN WALLIS: That's different from
MR. NIR: -- and growing experience with
implementation. However, EPUs are now being
implemented in 10 different BWRs, and that is now a
pretty significant number, and NRC review is ongoing
on an additional three plants.
For all these EPUs, plant safety margins
are maintained. We anticipate high volume of power
uprate requests in the coming years up to--
CHAIRMAN WALLIS: Do you expect that to
happen with almost every BWR?
MR. NIR: I'm sorry?
CHAIRMAN WALLIS: Do you think that will
happen with almost every BWR?
MR. NIR: Almost all, yes. It may not be
necessarily to the maximum of 120 percent of the
regional license, but to some extent, and most of them
a very large extent.
We anticipate approximately four BWR
requests per year. In anticipation of this load and
to facilitate NRC review and ACRS reviews, we propose
a streamlined approach --
CHAIRMAN WALLIS: Well, GE's approach is
MR. NIR: I will not dispute that.
It is experience-based. It is focused on
the potential impacts to power uprate, maintain safety
margins, and facilitate regulatory review.
We've met with you back in June 1998.
This was to describe the EPU approach as it was
evolving from the 5 percent Stretch Power Uprate
Program. There was no change to the licensing basis
plan. NSSS expected to be capable for EPU even though
there was a potential for operating pressure increase.
We anticipated that there will be some modification
needed for the balance of plant. which we identified
in a feasibility study initiated prior to the effort.
We limited operating domain to the maximum
extended load line limit analysis boundary, the
MELLLA. The plant-specific submittal was supposed to
be based on the generic LTR approved by the NRC in a
We discussed with you the ELTR-1, the
guidelines, and, two, the generic evaluations. That
was coordinated in conjunction, although in parallel
to, the Monticello EPU effort, and after Hatch Unit 1
and 2 pursued the same approach, we concluded that the
EPU approach is effective and acceptable, as a result
of the NRC and ACRS reviews.
We also met with you in June of 2001 to
initially describe to you the CPPU approach, and it
facilitates BWR power uprate application. We
introduced a simplification. We indicated it utilizes
established proven process, provides insurance that
all safety aspects are addressed, and we also
indicated effects and aspects that are not related to
power increase or separated from the power uprate.
We submitted the LTR initially in March of
2001. We received significant feedback from the NRC.
Subsequent to that, we revised the submittal and
resubmitted it in July of 2001.
The LTR version that we will review is
based on the July 2001 version, plus additional
changes as a result of subsequent RAIs from the NRC.
CHAIRMAN WALLIS: Are you going to tell us
what some of those significant changes were, or
MR. NIR: The significant changes from
REV-0 to REV-1?
CHAIRMAN WALLIS: Right.
MR. NIR: It was not included in the
presentation, but I can tell you now that most of it
had to do with the level of detail of the submittal,
the plant-specific submittal. What we proposed
initially was to reduce the level of detail. That was
not acceptable in certain areas, and we've corrected
that. The level of detail will be comparable to the
most recent EPUs.
CHAIRMAN WALLIS: Okay. So it's sort of
asking for more detail from the specific applicant in
the specific applications?
MR. NIR: Yes, that's right.
Also, I will talk about the different
dispositions of the various topics that are addressing
the CLTR, and the initial approach was somewhat
involved, and we simplified the disposition process.
These were the main two areas.
MR. SCHROCK: As I've read it, you've also
deleted the requirement for testing? Have I got that
MR. NIR: What I suggest is that we'll
wait until the closed session to discuss that.
MR. SCHROCK: That's okay, not appropriate
for open sessions.
MR. NIR: Yes.
MR. SCHROCK: Okay.
MR. BOEHNERT: I have a question. On this
key elements slide, how is the MELLLA Plus going to
impact this, if at all?
MR. NIR: Okay, let me defer that question
to the closed session.
MR. BOEHNERT: Okay.
MR. NIR: I will address that.
MR. BOEHNERT: Okay.
CHAIRMAN WALLIS: While we're on this
general area here, you folks tend to emphasize what
you're not changing: You're not changing the call
flow rate; we're not changing the pressure, and so on.
So the question always arises, how do you do it?
I think we have been convinced or
persuaded that this has something to do with clever
design of fuel and management of the fuel, and that's
really the key thing that you've brought technically
to this power management or power uprate, which makes
it possible. Is that a true statement? Am I wrong in
saying that it's the way in which you manage the fuel
which is sort of the key to making this happen?
MR. NIR: I don't think that this full
answer. I think it's part of it. It's only part of
it. I think part of it is just the BWR design and its
CHAIRMAN WALLIS: But you couldn't take
the BWR without doing something and just jack up the
power by 20 percent?
MR. NIR: You absolutely have to adjust
the core and fuel design, absolutely, and that is a
very challenging part of the design.
CHAIRMAN WALLIS: I know fuel is very
complicated and custom-built, and there's all kinds of
different areas and different enrichments.
MR. NIR: It's evolving. The pressure to
improve the fuel and core design was there prior to
EPU, just because of the economical pressure to
produce more energy --
CHAIRMAN WALLIS: I also think
computationally, when you have a very complicated
fuel, you've got to get your neutronics down right.
MR. NIR: Yes.
CHAIRMAN WALLIS: Really different bits of
fuel in different parts of the core behaving
differently with different histories and all that, but
an awful lot of things to keep track of. So maybe
modern computers make it possible to manage this
tremendously varied population of fuel elements.
MR. NIR: And we believe we are doing it
pretty well. Actually, one of the topics that we'll
discuss in the closed session will be the fuel and
core design. If needed, we can get into a little bit
more discussion on this. Actually, you get, I think,
a flavor of some of the design fuels that are being
CHAIRMAN WALLIS: Okay.
MR. NIR: I listed here actually the
evolution of the Power Uprate Core Program. We
started with 5 percent. It evolved to the EPU, 120
percent. That's actually 20 percent increase over the
original licensed thermal power.
The TPO, the thermal power optimization,
which is based on pool feedwater flow measurement
uncertainty, that's about a percent and a half or so.
And, finally, the constant pressure power uprate,
which we will discuss today.
I wanted just to add one more element and
ask to do actually to implementation. This is the
concept of online implementation, and I'm doing that
just to provide maybe the concept or the timeline so
that you can tie actually the SCR and your function in
this timeline to the power uprate process.
CHAIRMAN WALLIS: Now just to clarify
this, you're talking here about thermal power, 20
MR. NIR: Yes.
CHAIRMAN WALLIS: And the efficiency
actually goes down a little bit, doesn't it? Or
what's the effect on mechanical power?
MR. NIR: It depends. Efficiency may or
may not go down. Typically, when you uprate by 20
percent or so, you replace the high-pressure turbine.
CHAIRMAN WALLIS: But you take more
pressure drop in the steamline and things like that.
MR. NIR: That's true, but typically the
designs are much more advanced, and on balance, we
actually see potentially improving in efficiency just
because the technology on the balance of plant is
CHAIRMAN WALLIS: So have we concluded
that it is still 20 percent electrical? That would be
a good conclusion to make with that?
MR. NIR: Yes, it's --
CHAIRMAN WALLIS: Close enough?
MR. NIR: Close enough. You know,
actually, the efficiency depends, as you know, on the
environment. It can vary, but, yes, to your point, if
you perform the power uprate with constant pressure,
you do not change the turbine; you do not change the
system; efficiency will go down, I agree.
The vertical bars on this slide represent
the refueling outages. They are spaced typically
uniformly every 18 months or 24 months, and the
timeline represents the EPU process. We start with
the evaluation and then, following the NRC submittal,
NRC review, and the vertical line, indicated by SER,
is basically the combination of NRC review and ACRS
At that point the license is issued, and
with constant pressure power uprate, almost
immediately, without any power reduction, the power
can be increased.
Following this online implementation,
well, at that point the power may be limited by core
design or BOP limitations. Following the subsequent
refueling outage, these limitations can be addressed,
some modifications in fuel design and appropriate core
design, and then full power, EPU power can be
Let me just tell you that this approach
was successfully demonstrated both for Duane Arnold
and Dresden 2.
CHAIRMAN WALLIS: So how far along is
MR. NIR: Duane Arnold is right now at
about 113 percent of original thermal power, and I
believe that Dresden 2 is actually at the generator
limit. So they reached the maximum electric
production or their target, I would say. The thermal
power is lower. It's about 95 percent, I believe, of
the new rate of --
CHAIRMAN WALLIS: Anything unexpected
which happened would have been reported then? The
agency would know about it at this point?
MR. NIR: That's true. I believe that
both power increase ascensions were very successful
This is a summary of GE BWR power uprate
experience. On the left you can see most of the
initial power uprates were associated with power
increase. On the right the recent applications is
with dome pressure remaining constant, and as I
indicated, there are three applications, three
projects in progress: Clinton, Brunswick, and the two
Browns Ferry units.
Finally, this is actually a slide that we
showed you about six or seven months ago. Since then,
it changed actually pretty significantly. This shows
the addition to the U.S. electrical grid as a result
of GE BWR power uprates, and you can see that to date
we added 750 megawatts. That's a combination of the
5 percent uprate and the EPU. In progress is an
additional 800, and that will cover slightly above 50
percent of what we believe the potential for power
increase in the BWR fleet.
CHAIRMAN WALLIS: Explain this a little
bit. On the left it says, "Completed," and it starts
at 1,000 and it goes up to 1750? It looks like a 75
percent increase? I don't understand that.
MR. NIR: This is 750-megawatt electric.
CHAIRMAN WALLIS: So it's increased by 25
MR. NIR: I'm not following your question.
CHAIRMAN WALLIS: Well, there is sort of
a grayish shaded thing and then there's a blackish
shaded charcoal thing on top of it --
MR. NIR: Oh, yes. The charcoal is the
TPO. There you see the light is the 5 percent power
uprate. The darker gray is the EPU, and the dark
CHAIRMAN WALLIS: Oh, I see the light is
what you've already gained?
MR. NIR: Right, yes.
CHAIRMAN WALLIS: Okay. So it's not the
base. The base is zero.
MR. NIR: Absolutely. Yes, this is the
addition. I'm sorry.
MR. BOEHNERT: Yes, it's all addition.
MR. NIR: These are all additions due to
the different programs.
CHAIRMAN WALLIS: These are the total
megawatts added to the grid by these various
MR. BOEHNERT: Yes.
MR. NIR: Yes. So it's actually, as you
can see, a very significant contribution. The
potential there is equivalent of five units of 940-
megawatt electric and more than two of them are
already effectively online.
CHAIRMAN WALLIS: Does this include Ramone
Yankee? You say "Forecast," so I guess you're looking
into the future.
MR. NIR: The forecast -- well, the two
columns represent the potential that exists. The
actual will depend on the --
CHAIRMAN WALLIS: It is not going to be
specific about plants?
MR. NIR: That's right.
That is the conclusion of the open
CHAIRMAN WALLIS: Okay, thank you.
MR. BOEHNERT: We will go to closed
session now. So the transcriber will go to a closed
(Whereupon, at 1:25 p.m., the proceedings
continued in closed session. The open session resumed
at 5:25 p.m.)
CHAIRMAN WALLIS: Thank you.
MR. DONOGHUE: Good afternoon. My name is
Joe Donoghue, and I'm here for a very brief discussion
on where the staff review stands.
When this meeting was originally
conceived, the staff anticipated being at the stage
where we would be giving you, basically today, giving
you the draft SER, but we're a couple of weeks away
from that. I will give you that schedule in a little
First, I wanted to thank GE. The staff
really appreciates the effort that General Electric
put into this presentation. It is always good to hear
the overview and the material and meet people face to
I think you have heard a little bit about
this earlier in Dr. Nir's discussion. I will just
point out that the staff's got very recent experience
with extended power uprates, and I think you heard
earlier, there was a remark made that there are
reviews ongoing with the staff. I think Brunswick was
one of them, where the CPPU process is at least in
part being applied.
There are some common technical issues,
the ones we just talked about, just heard about, that
came up in some of these other reviews, this large
transient testing issue, and it is going to be covered
in the staff review on CPPU.
My final slide, the draft SER is coming
together as we speak. Large portions of it are
prepared by the staff, still under review by some
management. I think some of these parallel efforts --
I bring up one here, the Brunswick review, where the
staff actually did a lot of review at GE on some of
the analysis work, is benefitting the CPPU effort.
There is a balance we have to play because
a lot of the same people are involved in plant-
specific work that are doing the generic topical
report review here. But I think in total it is
probably a benefit. They probably learned enough to
actually help speed up the review process for this
As I mentioned, the draft SER we expect to
have delivered to the ACRS early February. That's
really all I had to say today.
CHAIRMAN WALLIS: Now we had some comments
on your previous SERs on power uprates which your
management assured us were being taken to heart.
MR. DONOGHUE: Yes.
CHAIRMAN WALLIS: There wasn't much
change, however, in the SER, the last one we saw. I
wonder if you are making more effort this time?
MR. DONOGHUE: Well, I know that the
reviewers are using information and comments that they
got from meetings on the other uprates.
CHAIRMAN WALLIS: I think we are not
concerned about the quality of the review. I think
our main concern is that it be properly reflected in
the SER itself, so that the written document properly
reflects all the work and consideration that the staff
put into the review of it.
Anyway, we have said this in letters, but
I just wanted to bring it up again because this was an
important point among my colleagues, that the SER
should reflect the quality of the technical review
perhaps more than some of the SERs tended to in the
MR. DONOGHUE: Well, our remark about the
plan for this SER is, and this is part of the process,
is seeing what questions the Subcommittee is going to
have, and we definitely are going to meet in the near
future, I believe, on the topical report itself.
Those comments will be factored into the SER. The
reviewers are prepared to use that. Because what we
are delivering to you is a draft SER with the intent
of factoring in any additional information that might
come up that we need to think about.
MR. BAJWA: Dr. Wallis, I can address --
MR. BOEHNERT: Identify yourself, Singh.
MR. BAJWA: This is Singh Bajwa, the NRR
Project Director for Project Directorate 3.
We are in finalizing the response to your
comments for the previous two applications which you
have reviewed. It is with the senior managers, and
there are a couple of issues which are in the final
stages. One is the SRP development for the power
uprate which is one of your recommendations, and the
second one, which you have just stated in reference to
the documentation of the reviews.
The present situation which we are facing
is that the two applications which you are receiving
this month, 95 percent of the work was completed prior
to receiving your comments. Staff is doing the best
to their ability with the time allowed and the
At the same time we are also seeing that
there will be a change in the SE development in light
of the CPPU if the topical report is approved. So we
have to keep that in mind, that the guidance which we
develop for our technical reviewers will be in light
of the new methodology to be used in developing the
So we are doing the best we know at this
point under given circumstances, but the staff has
definitely taken a very serious look to your comments
and the management was very mindful of that. At least
we believe that the Dresden/Quad City was a little bit
notch better than the first one, and I think hopefully
you will see the next will have an improvement over
the previous ones.
CHAIRMAN WALLIS: Yes, I think our
comments were rather independent of the actual
methodology. It was rather more a question of making
your technical case clearer to whoever read the SER.
That was a very general comment, but still I think
MR. BAJWA: I understand.
CHAIRMAN WALLIS: We are looking forward
to your next effort.
MR. BAJWA: All right, thank you.
CHAIRMAN WALLIS: Thank you.
Anything else we need to do now?
MEMBER KRESS: I take it you don't have
any real showstoppers at this time in your SER or
MR. DONOGHUE: None that I'm aware of.
I'm the Project Manager, not the Technical Reviewer,
but right now the inputs I have seen -- we have gone
through the RAI process on this. We have responses,
and reviewers are writing the SER input. So the
answer is, no, none that I am aware of.
CHAIRMAN WALLIS: So maybe with our
previous experience this will go quicker next time.
MR. DONOGHUE: That's the intent.
CHAIRMAN WALLIS: More streamlined, right?
MR. DONOGHUE: I didn't use that word.
I think process improvement is what
management just said.
CHAIRMAN WALLIS: Do my colleagues have
anything else to add?
I would appreciate your input to me in
terms of what we should say to the full Committee; by
email would be great from each one of you.
MR. BOEHNERT: You'll make your report to
the full Committee?
CHAIRMAN WALLIS: And I think we will make
a report, an oral report. I don't think there's any
letter involved this time around.
MR. BOEHNERT: No
CHAIRMAN WALLIS: Just what I would like
to be a consensus or at least a combination of views
that I have to put before the full Committee, I think
pretty briefly, at our next meeting.
Thank you very much.
Is there anything else we need to do, my
conscience over here?
MR. BOEHNERT: Not until tomorrow.
CHAIRMAN WALLIS: Okay, then I think we're
ready to -- what do we do?
MR. BOEHNERT: Recess.
CHAIRMAN WALLIS: We recess?
MR. BOEHNERT: Recess.
CHAIRMAN WALLIS: Recess until 8:30
tomorrow morning, when the topic will be entirely
MR. BOEHNERT: Yes.
CHAIRMAN WALLIS: Thank you very much.
Everybody who has been here contributed to our meeting
(Whereupon, at 5:33 p.m. the Subcommittee
recessed, to reconvene the following day, Thursday,
January 17, 2002, on a different matter.)