ML20140C146
| ML20140C146 | |
| Person / Time | |
|---|---|
| Issue date: | 03/28/1997 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| ACRS-T-2096, NUDOCS 9704020104 | |
| Download: ML20140C146 (49) | |
Text
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Official Transcript cf Proceedings O
NUCLEAR REGULATORY COMMISSION ACRST~ 2.0 9 6
Title:
Advisory Committee on Reactor Safeguards Thermal Hydraulic Phenomena Subcommittee OPEN SESSION TRO4 (ACRS)
RETURN ORIGINAL TO BJWHITE M/S T-2E26 Docket Number:
(not applicable)
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Location:
Rockville, Maryland O
Date:
Friday, March 28,1997
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, 3 Work Order No.:
NRC-1061 Pages 1-14/327-355 CloSE$ y) I T-B 2.G l
NEAL R. GROSS AND CO., INC.
Court Reporters and Transcribers O~ gi0 l
1323 Rhode Island Avenue, N.W.
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PUBLIC NOTICE BY THE l
UNITED STATES NUCLEAR REGULATORY COMMISSION'S l
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS l
l MARCH 28, 1997 The contents of this transcript of the proceedings of the United States Nuclear Regulatory
,(7 Commission's Advisory Committee on Reactor Safeguards on C) i MARCH 28, 1997, as reported herein, is a record of the discussions recorded at the meeting held on the above date.
This transcript has not been reviewed, corrected and edited and it may contain inaccuracies.
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NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RllODE ISLAND AVENUE, NW (202)234-443t WASlilNOTON DC. 20005 (202)234-4433
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UNITED STATES OF AMERICA 2
NUCLEAR REGULATORY COMMISSION i
,m s
i
>LJ 3
+++++
4 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 5
+++++
6 THERMAL HYDRAULIC PHENOMENA SUBCOMMITTEE 7
+++++
8 FRIDAY 9
MARCH 28, 1997 10
+++++
11 ROCKVILLE, MARYLAND 12
+++++
13 The Subcommittee met at the Nuclear Regulatory
[ \\
14 Commission, Two White Flint North, Room T2B3, 11545, 15 Rockville Pike, Rockville, Maryland, at 8:30 a.m.,
Thomas 16 S.
Kress, Chairman, presiding.
17 18 MEMBERS PRESENT:
19 THOMAS S.
KRESS CHAIRMAN 20 MARIO H.
FONTANA MEMBER 21 ROBERT L.
SEALE MEMBER 22 23 24
(~N.
(]
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ACRS STAFF PRESENT:
2 John Larkins Executive Director
\\v/
3 Paul Boehnert 4
Noel Dudley l
5 Amarjit Singh i
6 7
ACRS CONSULTANTS PRESENT:
8 Ivan Catton 9
V.J.
Dhir 10 Novak Zuber
\\
11 12 ALSO PRESENT:
13 Larry Hochreiter f3
)
v' 14 Bob Kemper 15 Dan Garner 16 17 18 19 20 21 22 23 24
./^s) 25 NEAL R. GROSS COURT REPORTERS AFD TRANSCRIBERS 131'3 RHODE ISLAND AVE., N W.
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A-G-E-N-D-A j
2 Aaenda Item Pace
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3 Introduction, Thomas Kress 4
4 NRC Presentation 327 5
Sucommittee Caucus 336 i
6 7
i l
8 9
10 11 12 13 C 'N
,b 14 15 16 17 18 19 20 21 22 23 24 rm
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P-R-O-C-E-D-I-N-G-S 2
(8:35 a.m.)
fs 3
CHAIRMAN KRESS:
The meeting will now please 4
come to order.
5 This is a meeting of the ACRS Subcommittee on 6
Thermal Hydraulic Phenomena.
I 7
I am Tom Kress, the present chairman of the 8
subcommittee.
ACRS members in attendance are Bob Seale, 9
Mario Fontana, and myself, of course.
And we have some 10 consultants here, Ivan Catton, Novak Zuber and V.J.
Dhir.
11 The purpose of this meeting is for the 12 subcommittee to continue its review of the Westinghouse 13 test and analysis program being conducted in support of (k) 14 AP600 design certification.
15 For this meeting the subcommittee will hear 16 presentations from Westinghouse on the use of the 17 Westinghouse COBRA / TRAC code for calculation of AP600 18 longterm cooling performance.
19 The subcommittee will gather information, l
l 20 analyze relevant issues and facts and formulate proposed l
l 21 positions and actions as appropriate for deliberations by 22 the full committee.
23 Paul Boehnert is the cognizant ACRS staff j
24 engineer for this meeting.
Notice of this meeting was r~N l
25 previously published in the Federal Register on March 10,
(,)
\\
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1 1997.
2 With the exception of this opening session
-.s l
i 3
and the last two sessions of this afternoon, this meeting 4
will be closed to the public to discuss Westinghouse 5
proprietary information.
6 A transcript of the meeting is being.kept.
7 It is requested that speakers first identify themselves 8
and speak with sufficient clarity and volume so that they 9
can be readily heard.
10 We have received no written comments or 11 requests for time to make oral statements from members of 12 the public.
13 The subject that we are dealing with is the g
1 6
\\ /'
14 proposed use of OSU APEX data to validate the Westinghouse 15 COBRA / TRAC code for use in predicting the behavior or 16 AP600 under longterm cooling conditions.
17 You know when you reach the longterm cooling 18 conditions, the blow down phase is over and things are 19 changing rather slowly, the decay heat is at a relatively 20 low level.
Steam that gets generated goes out the ADS-4 21 valve, generally, and maybe some out a little break.
22 But, it is condensed and then refluxes back 23 to the sump, fed back to the vessel by gravity again.
24 These slowly changing conditions do look to r~N
(
)
25 me like they are a quasi-steady state and Westinghouse NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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claims that in order to use the code to analyze the test 2
data under these conditions, it really takes an awfully
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3 long time because things have dragged way out and are 4
changing slowly and it is time consuming and expensive.
5 So, Westinghouse has proposed what they call 6
a windows approach which has nothing to do with PCs.
What 7
this is, of course, is looking at specific shorter time 8
increments of the full transient and letting the code make 9
an initial transient from initial conditions to arrive at 10 the quasi-steady state conditions for that little time 11 window.
12 Then you would use the ability of the code to 13 predict that window area as a way to validate it for the C\\
14 full transient.
s 15 The input for the initial conditions comes 16 directly from the test data.
I am not sure what all these 17 inputs are but I am sure they would include things like 18 the initial decay heat, the various levels of water in the 19 vessel and the pressure, perhaps even the temperatures.
20 But se will hear more about that later.
21 The issue before us is, is this a legitimate 22 approach to validate in the code?
And I remind members 23 and consultants that what we are really interected in here 24 is how well does the core stay covered.
That is basically l
(~n
(_)
25 the bottom line thing that we are interested in.
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And, are there any pitfalls to this approach?
2 I think the staff thinks there could be cumulative effects 73 i
L~'/
3 that are missed that if you just look at increments 4
instead of the full transient progressing all the way that 5
there might have been cumulative effects that cause 6
increasing divergence data from the results that aren't 7
captured by this approach.
8 With that as introductory comments, I ask if 9
any of the c;nsultants want to make a few preliminary 10 remarks before we get started or ask any questione that 11 need to be focused on?
12 MR. CATTON:
I would just to maybe put some 13 things on the table so that we can be sure that they get
/~N 14 discussed.
15 CHAIRMAN KRESS:
Good idea.
16 MR. CATTON:
Longterm cooling is very 17 different from other types of ECCS problems that we have 18 to deal with.
19 What wasn't clear to me in looking through 20 this is what constitutes an EM model.
21 Now, I don't know that the reports ever 22 really came out and said that it is an EM model; but the 23 hints are kind of there.
I would like to hear the problem 24 be really well defined; just what is it you are looking at (3
(,)
25 so that one can then think about whether or not this NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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windows approach makes any sense.
f3 2
The second thing is the code itself.
The i
/
a
3 windows approach with a complex code like COBRA / TRAC may 4
or may not converge to the correct answer and you can't do 5
the usual space / time convergence tests with codes like 6
COBRA / TRAC.
7 So, you really don't know where you are at.
8 It is highly empirical as a result.
9 And you have to start somewhere.
And where 10 they start is with initial conditions taken from the AP600 11 tests and I think in this instance they take them from 12 APEX or the OSU facility.
13 Now, if indeed I had a ccie where everything
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14 was healthy -- I am not saying that COBRA / TRAC ia 15 unhealthy.
But if I knew everything, I wouldn't have to 16 go through an initial transient.
17 CHAIRMAN KRESS:
If you fix those initial 18 conditions.
19 MR. CATTON:
If I take the set of data and I 20 put it in to the code as initial conditions and it is a 21 quasi-steady program, I wou]o leap right on to the curve 22 and just track it.
But apparently that doesn't happen.
l 23 Now why Jocsn't it happen?
It doesn't happen 24 because probably the data set that you get from a facility 1p
(_)
25 like OSU is not going to be complete.
And I think to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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expect it to be complete is foolishness.
So we know that 2
it is not complete.
,3
(
)
x_/
3 When you set up the code to run, obviously 4
somethings are a little bit out of whack.
It was 5
comforting to see that the code does converge tot what 6
they felt was correct.
7 So, is there anything wrong with the window?
j 8
I think if they show enough of this, probably not 9
The question that I have then, is how the 10 hell do I get the initial conditions to run the window 11 when 1 am dealing with a real plant?
12 Somehow, you have to track that whole damn 13 transient because the things that become the boundary
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14 conditions when you run the quasi-steady case, they are 15 changing, slowly albeit, and somewhere you are getting 16 those.
17 I would like to see a description of the 18 process that enables us to grab hold of it and I couldn't 19 get that out of any of the documentation.
20 And by the way, your curves are really 21 crappy.
Half the time I can't figure out which is the 22 COBRA calculation and which is the data.
You use these 23 dash things.
Sometimes there are four citations at the 24 top of the graph and two curves.
I mean, what am I (3
s_,)
25 supposed to do with that?
t NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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With that, I will stop.
2 CHAIRMAN KRESS:
Ivan, let me ask.
My
\\,/
3 mpression from reading the information that I had was 4
that the windows approach was for using the data from the 5
APEX test to validate the code.
6 I didn't see anywhere that they planned on 7
using the windows approach for the actual calculations for 8
the AP600.
9 MR. CATTON:
But that is the name of the 10 game, isn't it?
11 MR. HOCHREITER:
No.
12 This is Larry Hochreiter, Westinghouse.
13 No, we are going to use the windows approach 14 for the plant calculation.
15 CHAIRMAN KRESS:
Okay.
So Ivan's question is 16 relevant.
j 17 MR. HOCHREITER:
With the exception that we 18 do not use the initial conditions from the test or plant 19 calculations.
20 CHAIRMAN KRESS:
Of course.
But you will 21 have to use some sort of extrapolation process to get the 22 initial data.
l 23 MR. HOCHREITER:
Well, we are kind of getting 24 into our presentations.
But we will use the conditions at f%()
25 the beginning of longterm cooling from previous NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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calculations for either a large break or small break 2
p-(_'
3 CHAIRMAN KRESS:
Oh, from a previous 4
calculation.
5 MR. HOCHREITER:
Right.
If we do a small 6
break, we will have NOTRUMP.
We will run NOTRUMP through 7
stable IRWST injection.
Then we have a set of initial 8
conditions that we can then use for longterm cooling.
9 CHAIRMAN KRESS:
But you are right; it sounds 10 like we are getting into the presentations.
11 MR. HOCHREITER:
Right.
12 MR. CATTON:
If you start off Larry, maybe 13 with a nice picture of how you are going to use COBRA / TRAC i
(_/
14 and the windows approach in an evaluation of the plant, 15 then we can see how all of this fits.
16 Does that screw up your presentation?
- Yeah, 17 but then we usually do.
18 MR. HOCHREITER:
I guess it is just a 19 question of where we sant to screw it up.
20 Why don't you give us a few minutes.
21 CHAIRMAN KRESS:
Okay.
Well, we'll continue.
22 or maybe we ought to wait until they could listen here.
23 MR. BOEHNERT:
Use the mike, Novak.
24 MR. ZUBER:
I have several but I would like
(
)
25 to keep them for the end.
x/
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I agree with what Ivan is saying.
The only 2
thing that I would is I would like Westinghouse to address
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3 why do they have to use this approach and really spell it.
4 Because this would lead us into something else that should 1
5 be interest to the committee later on.
6 MR. CATTON:
It could be that it is because j
7 they own the Cray.
8 CHAIRMAN KRESS:
We'll loan them our Sun work 9
station.
10 V.J.?
11 MR. DHIR:
You know, I didn't see anyplace I
12 where they have shown that the correlations and models 13 which are used in COBRA / TRAC for the slow transient are
,7 3 I
k/
14 applicable to the conditions for which they are using 15 them.
16 There are also compensating errors but they 17 may be canceling out.
But one has to be assured that the 18 correlations in the code which are applicable are usable.
19 CHAIRMAN KRESS:
Okay.
Do any of the other 20 members present want to make any comments before we start?
21 Bob Seale?
22 MEMBER SEALE:
Well, I guess the fact that 23 you get this tendency to home in on the right answer, if 24 you will, Ivan, when you do these calculations for the (j
25 OSU tests, suggests that you have all the important NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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phenomena as far as the OSU experiments are concerned.
2 I assume that the scaling tells you that at fs
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least you think you have all of the phenomena as far as 4
the real thing is concerned, too.
5 MR. CATTON:
The concern that I have --
6 certainly what you say is correct.
But when you are 7
looking at a long transient, thousands and thousands of 8
seconds and you are marching along, small errors tend to 9
accumulate.
10 You can end up particularly with a code where i
11 a code and spatial convergence has not bee demonstrated 12 and you tend to move off track.
There are lots of 13 examples where they're good clean CFD that this happens to
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14 you.
15 You have to be very careful.
16 MEMBER SEALE:
Physics can drive you off the 17 track and mathematics can drive you off the track.
18 MR. CATTON:
But it is just a numerical 19 representation of the problem, and with these big 20 systems's coeds, it is not done with rigor.
As a result 21 you just don't know.
22 And that is the concern.
How are you going 23 to do this?
How are you going to put it all together when 24 you have to walk out in time so far?
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(,)
25 CHAIRMAN KRESS:
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anything.
2 MEMBER FONTANA:
I have some but I will wait
~.
/LJ 3
for our presentations.
4 CHAIRMAN KRESS:
With that then, at this 5
point I think we have to close the meeting which you know 6
how to do.
7 Anyone who doesn't belong here, please leave.
8 MR. BOEHNERT:
Hey Tom, that's right.
9 (Whereupon, at 8:49 a.m.,
the proceedings 10 went immediately into a Closed Session.)
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21 22 23 24
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CHAIRMAN KRESS:
We are now in open session.
2 MR. LOIS:
Thank you, Mr. Chairman.
(7_ )
3 (Slide) 4 MR. LOIS:
I'm Lambros Lois.
I'm designated 5
the reviewer for the long-term cooling for AP600.
And 6
I've been with the agency since in case you're asking for l
7 credentials almost 25 years.
8 (Slide) 9 MR. LOIS:
Right now let me show you what we 10 are trying to do is the windows approach under review.
11 The criterion is core coverage.
And that explains why I 12 could not answer more specifically the question that was 13 asked before by Dr. Dhir, namely whether or not we caught r w]
- (_-
14 this particular discrepancy in the flow.
15 Our approach questions were geared primarily 16 towards level; therefore, combined inflow and outflow.
We 17 did question, in particular, the SB01, that particular 18 one, because it seems to have the highest discrepancies 19 than any of the other three tests.
20 We received responses to a bunch of RAIs 21 about a couple of weeks ago.
And we are having that j
1 22 review right now.
We still have some outstanding j
1 23 questions which were directed to Westinghouse.
And what 24 Westinghouse doesn't know is they are going to receive a (x_-)
25 few more.
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Independently, beyond what we have received 2
from Westinghouse, we have confirmed the quasi-steady
,-l i
'~'
3 state nature of the transient using RELAP5 and MOD 3.
4 CHAIRMAN KRESS:
How did you do that?
5 MR. LOIS:
RELAP5/ MOD 3 has even benchmarked 6
versus a number of other transient tests.
We utilized 7
that one.
8 CHAIRMAN KRESS:
You actually ran it for a 9
long-term cooling transient?
10 MR. LOIS:
Yes.
11 CHAIRMAN KRESS:
Okay.
How long did it take?
12 MR. LOIS:
I do not know.
I was not 13 responsible for that.
That information came from
/^N x/
14 Research.
The questions were asked --
15 MR. ZUBER:
Research ran a RELAP calculation 16 on this problem for long-term cooling?
- 1. 7 MR. LOIS:
Yes.
And they had to --
18 MEMBER SEALE:
Norm Lauben's here.
19 MR. LAUBEN:
Norm Lauben from Research.
20 In the long-term cooling report which was 21 given to ACRS about the capability of RELAP to do 22 long-term calculations, there are a number of calculations 23 described in this.
Also, this was information we provided 24 to the ACRS subcommittee in Los Angeles last month.
7g()
25 But to answer your question in short, with NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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the boundary conditions that were used in that document, 2
it takes about one to two days to do a RELAP calculation 7-3 for 50,000 seconds.
4 MR. CATTON:
It's interesting how these 5
things are phrased.
"RELAP5/ MOD 3 Confirmed Quasi-steady 6
state nature of the transient."
That isn't what you did.
7 The OSU experiment confirmed the quasi-steady nature.
8 What you did is you showed that indeed RELAP5/ MOD 3 9
predicts.
You didn't confirm it.
You knew it.
10 If you put "could" in there, it would be all 11 right.
12 MR. LOIS:
Yes.
You can look at that that 13 way.
hctually, what we are trying to do is to see whether
,e3
(
)
14 or not calculating numerically, are there any other 15 phenomena that the code could lend it --
16 MR. CATTON:
You can run the code out to 17 steady state, and it has some meaning.
That's what you 18 investigated.
19 MR. LOIS:
Yes.
We can look at that later.
20 Questions that we are asking ourselves right 21 now and trying to extract out from the data are:
Does the 22 WCOBRA/ TRAC provide the correct solution versus OSU, of 23 course, since that's what we have to validate against?
Is 24 the solution conservative for the AP6007 Again, these are
,ey q_)
25 the questions that Westinghouse has been elaborating all i
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day long today.
And is the solution analytically stable?
2 That's what has led into the extended calculations and, of i
7s
(
)
3 course, some of the thoughts that Westinghouse has been l
1 4
going over.
5 And is the range of the experiments adequate?
j i
6 Well, this is kind of an old question as to:
In other i
7 words, would it lead to the same long-term cooling 8
response if one were to have a large-break LOCA and a 9
small-break LOCA?
The answer I guess we have already 10 known that it is independent of tne size of the break.
11 However, beyond those questions, --
12 (Slide) 13 MR. LOIS:
-- we have some other issues that rN
!i
')
14 we considered independent again from the submittal from
)
15 Westinghouse.
It was the oscillations of the OSU 16 experiments potential and the potential oscillations in 17 the AP600, the flooding of the dead spaces.
18 Again, initially the head was supposed to be 19 the 107 or 108 and then eventually one would have a more 20 conservative approach if you assume that we have the dead 21 spaces flooded, the wall to wall we saw earlier from Dr.
22 Hochreiter's presentation.
And we'll try to interface 23 with the containment with the GOTHIC and the solutions 24 that they are providing.
,.\\
j 25 This is a difficult issue since at this time NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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it is difficult to get numbers or solutions that GOTHIC 2
has provided.
But hopefully by the time we are ready to
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)
x'/
3 decide as to what to do with our response, we may have 4
some more definitive responses from GOTHIC.
5 The robustness of database.
Risk has been 6
put up.
And this is in the back of our minds.
We're 7
trying to deal with it and wrestle with it, namely we only 8
have one set, a set from one, experimental setup.
One 9
conveys questions as to what that means.
However, we do 10 have other considerations.
That's just the scaling, the 11 PIRT, the conservatisms, and so forth.
12 So we're trying to take a lock as an integral 13 problem and not isolate the question as to:
Could there n
14 be a bias in the set in the fact that they come only from 15 one point, from one type of facility?
16 And, of course, is the PIRT acceptable?
17 There should be a question mark there.
We're settling 18 with that and the Appendix K use of the WCOBRA/ TRAC.
19 Well, responding to Dr. Hochreiter's comment, 20 at this stage we have not published anything.
So if 21 anybody says, "Well, have you decided on the PIRT?" I will 22 say I don't know because we haven't formally responded to 23 anything.
So it's in that context that I said there 24 should be a question mark next to it.
,.(,)
25 MR. ZUBER:
May I make a comment?
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MR. LOIS:
Yes, sir.
2 MR. ZUBER:
I think this report, the scaling p
i 4
3 was submitted to NRR, I think, just beginning of March.
I 4
think the 4th or 5th, something like that.
5 MR. LOIS:
Yes.
6 MR. ZUBER:
I think the PIRT also.
7 MR. LOIS:
Yes.
8 MR. ZUBER:
So there was little time for 9
anybody to respond and evaluate.
10 MR. LOIS:
Thank you.
Thank you.
- Again, 11 it's in the context that it has not been responded to in a 12 formal way.
13 MR. HOCHREITER:
That's not true.
This PIRT
,e k_)
14 was in the WCAP.
We're talking about the long-term 15 cooling PIRT.
Okay.
That PIRT was in the WCAP that was j
16 issued at the beginning of November.
17 MR. ZUBER:
Okay.
Okay.
18 MR. LOIS:
Yes, yes, yes.
And also I may --
19 I'm sorry.
20 MR. ZUBER:
See, there are many versions.
21 Wait, wait, wait, wait, wait, wait.
Based on the 22 discussions I heard at this meeting, they're still going 23 to change it.
24 MR. HOCHREITER:
We're not changing it.
,n
\\
(
25 MR. ZUBER:
Well, then talk to --
s_)
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333 1
MR. HOCHREITER:
Unless we get feedback from 2
the NRC for something that --
73
(
)
3 MR. ZUBER:
Wait, wait, wait, wait, wait.
4 I'm sorry.
I'm sorry.
You are talking --
5 MR. BOEHNERT:
You're about the PCCS.
6 MR. ZUBER:
I'm talking about the 7
containment.
I'm sorry.
I'm sorry.
You are right.
8 MR. LOIS:
Thank you.
Thank you.
9 And finally, of course, is the Appendix K use 10 of the WCOBRA/ TRAC, which again we have to figure into our 11 final decision on the overall situation.
So, therefore, 12 we're still working with it, and hopefully we'll come back 13 with a response.
/~'\\
's_)
14 As far as the schedule of problems is 15 concerned, hopefully we think we need about eight weeks 16 from the time we have the last response from Westinghouse 17 to come back with -- this is our estimate -- with a final 18 product on that.
19 Thank you.
20 CHAIRMAN KRESS:
How do you feel at the 21 moment about the windows approach?
22 MR. LOIS:
I'm sorry?
23 CHAIRMAN KRESS:
How do you feel about the 24 windows approach for validating WCOBRA/ TRAC?
(A) 25 MR. LOIS:
We feel it's possible, yes.
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1 a technique which could be viable.
I don't have an 2
opinion as to yes or no as far as acceptability is
,-\\]
3 concerned because I don't make the decision by myself.
So 4
based on that, the technique is viable.
5 CHAIRMAN KRESS:
Any other questions from 6
consultants or members?
Yes?
You're welcome to ask a 7
question.
6 MR. McINTYRE:
In your first slide, I think 9
you said:
Westinghouse doesn't know about this, but there 10 are some more RAIs on the way.
11 MR. LOIS:
Yes.
12 MR. McINTYRE:
What are the units on a few?
13 MR. CATTON:
Do you want to know if it's tens V
14 or hundreds?
15 MR. McINTYRE:
Well, ones, tens, hundreds.
16 Those are the --
17 MR. LOIS:
It's less than ten.
18 MR. McINTYRE:
Less than ten?
19 And finally, of course, is the Appendix K use 20 of the WCOBRA/ TRAC, which again we have to figure into our 21 final decision on the overall situation.
So, therefore, 22 we're still working with it, and hopefully we'll come back l
23 with a response.
24 As far as the schedule of problems is
,3 i
")
25 concerned, hopefully we think we need about eight weeks v
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from the time we have the last response from Westinghouse 2
to come back with -- this is our estimate -- with a final
,s
(
)
3 product on that.
4 Thank you.
5 CHAIRMAN KRESS:
How do you feel at the 6
moment about the windows approach?
7 MR. LOIS:
I'm sorry?
8 CHAIRMAN KRESS:
How do you feel about the 9
windows approach for validating WCOBRA/ TRAC?
10 MR. LOIS:
We feel it's possible, yes.
It is 11 a technique which could be viable.
I don't have an 12 opinion as to yes or no as far as acceptability is 13 concerned because I don't make the decision by myself.
So
/ h
(
1
\\ s' 14 based on that, the technique is viable.
15 CHAIRMAN KRESS:
Any other questions from 16 consultants or members?
Yes?
You're welcome to ask a 17 question.
18 MR. McINTYRE:
In your first slide, I think 19 you said:
Westinghouse doesn't know about this, but there 20 are some more RAIs on the way.
21 MR. LOIS:
Yes.
22 MR. McINTYRE:
What are the units on a few?
23 MR. CATTON:
Do you want to know if it's tens 24 or hundreds?
p)
(,
25 MR. McINTYRE:
Well, ones, tens, hundreds.
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Those are the --
2 MR. LOIS:
It's less than ten.
7S
(
)
3 MR. McINTYRE:
Less than ten?
4 MR. LOIS:
Half a dozen or thereabouts.
5 MR. McINTYRE:
These are the last?
6 MR. LOIS:
Hopefully, yes.
7 MR. BOEHNERT:
It depends on your answers, I 8
guess.
9 MR. LOIS:
That's true, of course.
10 Thank you.
11 CHAIRMAN KRESS:
Well, thank you very much.
12 We are now in a caucus mode.
And at this 13 time, I would --
,~
4
/
4 14 MEMBER SEALE:
Could I ask a question?
15 CHAIRMAN KRESS:
Yes, you may.
16 MEMBER SEALE:
What is it that we will be 17 expected to do in the short term insofar as a full 18 Committee action?
19 CHAIRMAN KRESS:
I don't think anything.
I 20 think right now Westinghouse is interested in our 21 reactions, which they have gotten throughout this meeting.
22 I don't think you're asking for anything else 23 at this stage, are you?
24 MR. McINTYRE:
We would have liked you to say
,a
(_,)
25 it was dandy.
]
I I
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1 MR. HOCHREITER:
And then write a letter to l
2 that effect.
l
,\\' '}
3 MEMBER SEALE:
That's premature.
4 CHAIRMAN KRESS:
Before we write a letter, 5
we'll have to schedule a full ACRS.
6 MR. BOEHNERT:
Well, staff hasn't completed 7
their review either.
8 CHAIRMAN KRESS:
And staff hasn't completed 9
their review.
So I don't think we're --
10 MR. McINTYRE:
Well, we told you what we'd 11 like.
I thought that was the question on the table, Mr.
12 Chairman.
13 CHAIRMAN KRESS:
I guess realistically about
(_//
14 all you can get is our reactions at this time.
15 MR. McINTYRE:
Yes.
And I think that's fair.
16 I think we have some good input.
We'll go back and get 17 the transcript and look at it and think about this and 18 look at the next round of the last round of the last six 19 RAIs from Lambrose.
20 CHAIRMAN KRESS:
So, with that, I think I'll 21 try to help with our reaction by inviting first the 22 consultants if they want to make some summary comments on 23 what they've heard today.
And we'll start with Ivan.
24 MR. CATTON:
In my view, I think what we t"N f
25 heard today clearly demonstrates that the window approach
\\__,)
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could achieve the desired result, namely an evaluation of 2
long-term cooling.
7_
\\
)
~'
3 The questions that remain have to do with 4
what is selected as conservative boundary conditions.
And 5
from what we heard today, I'm not convinced that this has J
6 been done except for things like single failure, Appendix 7
K decay heat.
8 There's a need, I believe, to revisit the 9
data / code comparisons of full pressure drop relationships 10 to assess the ability of the code to do blind predictions 11 of flow resistance under a number of different 12 circumstances.
13 It's not clear in my mind how our ability to t'x t
i/
14 predict scales when compensating effects are possible.
15 And the reason I focus on the flow resistance is because 16 it's a balance.
You have the flow in, and you have flow l
17 out.
And the resistances basically govern what goes on.
18 As far as the conservatism and demonstrating 19 it, I think that it would really be helpful if a set of 20 calculations of containment pressure were put in front of 21 us, a maximum, a best estimate, and a minimum, because 22 from that, you can very quickly get to what you need to do 23 a set of calculations for the long-term cooling.
24 And part of what was missing, you see, is if gy t,
)
25 I have a high pressure, I still have to deal with a low v
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temperature because of stratification.
You can always 2
argue that the upper temperature is set by the pressure s
i
\\
\\
)
' ^ ~ '
3 but the lower temperature is not.
And when you start 4
looking at these things separately, what does it do?
5 And, finally. -- let's see -- I just want to 6
preach a little bit.
This whole approach of these big 7
codes and all these calculations seems to me a waste of 8
everybody's time.
9 I think a great deal of resources are spent 10 in following convoluted, archaic paths, the result being 11 hard to follow and a disservice to both industry and the 12 public.
That's a Zuber kind of statement, but I couldn't 13 resist.
rm I
\\-)
14 I understand the history that's behind it, 15 and I guess in some respects I've been a part of it.
16 Nevertheless, quasi-steady flow and you're using this huge 17 code when you could do simple calculations.
18 Now, let's just for a moment think about what 19 you could do with the simple calculations.
You can change 20 things, like the level, and you could figure out what is 21 the lowest level at which this thing still works and then 22 make arguments about you're going to have a level higher 23 than that because there's just too damn much water.
You 24 can address a lot of the issues that way if you do a l
/
( j) 25 quasi-steady type analysis.
When I say " quasi-steady," I NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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340 1
don't mean extrapolating to the steady state using TRAC or 2
any other such codes.
7-~b 3
CHAIRMAN KRESS:
Why does it have to be 4
quasi-steady?
Why not just steady state?
5 MR. CATTON:
Well, that's what quasi-steady 6
means.
You're going to take a series of points.
It's 7
just that the response to --
8 CHAIRMAN KRESS:
But you're going to do a 9
steady state analysis.
10 MR. CATTON:
Yes.
Okay.
If you want.
11 Normally when somebody says, "I'm going to do a 12 quasi-steady calculation," something is varying with the 13 system response instantaneously to it.
(\\/
14 In this case, I mean, I have never seen 15 anything closer to quasi-steady or to steady state.
I 16 mean, those levels and everything else are just flat.
17 CHAIRMAN KRESS:
What about all of those 18 fluctuations in the red lines?
19 MR. CATTON:
Well, you're going to have to 20 deal with those, too, but you deal with them differently.
21 That's it.
22 CHAIRMAN KRESS:
Okay.
Novak, do you want to 23 add some to this?
24 MR. ZUBER:
A little bit.
(~)
(,/
25 CHAIRMAN KRESS:
Do you want to defend NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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341 1
yourself?
2 MR. ZUBER:
Let me say that being a man of i
3 advanced age, I appreciate more and more the wisdom of old 4
proverbs.
And one that comes to my mind now is:
Old men 5
pay for the sins committed by the escapades of their 6
youth.
7 (Laughter.)
8 MR. ZUBER:
Well, I won't comment to this as 9
far as me personally, but let me say applying to the 10 cause.
What we have seen here today in this effort, I 11 think this is exactly what I understand.
We are paying i
i 12 for the sins committed by applying a code which was 13 developed for a different purpose, for different kinds of
(~)
kl 14 transients 20 years ago, which after 20 years of working 15 with different computers, we reached the level I think we 16 cannot really make much improvements.
And I think the 17 best example is that you need 200 days to perform one 18 calculation.
This really shows that this approach has a 19 limit of usefulness.
20 To continue on this approach, I'm talking 21 about the future.
And I'll make a suggestion that can be 22 done to address it a little bit later.
To use this 23 approach based on two fluids or three fluids and to 24 involve resources in this country tied to this problem for
'/N
()
25 the next five or ten years, if I may use an expression, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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will be a criminal thing to do.
2 It will not provide NRR with the tools they 7 _.
i\\
/
3 need.
It will put concrete blocks on the industry because 4
the industry always follows wha; NRC is doing.
It will be 5
a disservice to the technology and to the industry.
6 The only benefit it will be, for people who 7
conduct these calculations because they are lengthy and 8
expensive.
I think this will be no the producers of the 9
reactor but maybe some consulting firm or some national 10 laboratory or some university because they will have 11 guaranteed to generate so many Ph.D. students for the next 12 ten years, like they do it in particle research.
13 I think what we have se en today is the best
\\_/
14 that can be done with the tools we have.
What makes me 15 displaced as a technical man, that it's really using this 16 approach but a much better and more defensible approach 17 could be done by the way Ivan outlined, I think V.
J.
18 mentioned also.
19 Some of these problems. like a very simple 20 boiling water reactors, can be done very simple 21 calculations and good sensitivity a7alysis.
I refuse to 22 accept any responsibility that at least I or some of my 23 colleagues are insisting and asking Westinghouse to do l
24 these heavy calculations.
I doubt it that NRR is
(" 3
( )
25 requesting them to do it.
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MR. HOCHREITER:
That's right.
2 MR. ZUBER:
They are?
i
,_N f
l 3
MR. HOCHREITER:
No, no.
This was our 4
choice.
1 5
MR. ZUBER:
Okay.
I think that this approach j
l 6
could have been made more efficient, more defensible 1
7 having analyzed a problem like a boiling water with simple 8
models and many sensitivity analyses.
9 I hope -- Larry, you mentioned this -- that 10 perhaps maybe or so th.'s can be done in the future.
I 11 would really urge you to oc 4.t.
I don't think it will 12 cost much money.
)
13 And you will have a much better tool and n
i i
V 14 something defensible if it comes in the future.
I think 15 simple codes with boiling water reactors with some other 16 additional components are available.
And I think you can 17 do it as part of a Ph.D. program or something like this.
18 I think this should be done.
19 Now, concerning this approach, I agree 20 completely with Ivan.
I think it's reasonable.
It's not 21 elegant.
Technically, I don't like it, but I have 22 accepted it because there is nothing else you can do at 23 this point in time having made the decision.
24 The only thing I would urge you to do would r(h) 25 be to really examine very much the conservatism you have, NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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344 1
address them and evaluate them, what is the conservatism, 2
what is the effect, how much it is, and prepare it and put 7-s) t 3
it in a package.
I think then you will have something you 4
can defend and sell.
5 But I would also urge you to do these 6
calculations with a simple model in the next year or two.
7 Actually, you can do it probably in half a year.
8 CHAIRMAN KRESS:
Thank you.
9 V.
J.?
10 MR. DHIR:
Okay.
I'm much younger than my l
11 two senior colleagues.
So I will --
12 (Laughter.)
13 MR. ZUBER:
No, no, no, no.
Look --
f
\\
t
)
's/
14 CHAIRMAN KRESS:
You don't have any sins of 15 your youth?
16 MR. DHIR:
No, no.
17 MR. ZUBER:
He didn't want to say older 18 because he thought he would insult me.
If you said an old 19 man, you're not discriminating.
But senior gives you a 20 different connotation.
21 MR. HOCHREITER:
No, no.
That just means 22 he's still sinning.
That's what it means.
23 MR. DHIR:
But my comments are very similar 24 to what has been said by Ivan and Novak.
I don't think
('~%
y,/
25 WCOBRA/ TRAC is the right code for the long-term NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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1 345 1
I think it should have been much better and 2
much more valuable if Westinghouse had devoted this effort 1
7
(
)
~
3 to develop a simplified code, which could be just looking 4
4 at balancing between friction and your driving heads.
5 Number two, I would make the point that 6
windows approach can be applied. to steady these slow 7
transients with WCOBRA/ TRAC as the progression of the 8
transient is quite quasi-static.
However, the danger in 9
using this windows approach is that one can be fooled by 1
10 missing a certain critical scenario, the critical 11 conditions that may occur.
12 An example in my mind at least is the large 13 oscillations that may occur.
And if one school dries out,
/x 1
1
's /
14 it may be difficult to reflood or you may go into film j
15 boiling.
16 With respect to code validation with OSU, 17 generally you found agreement was good.
But there were 18 cases when there were large discrepancies between the code 19 predictions and the data.
It is somewhat unfortunate that 20 Westinghouse did not make any attempt to determine the 21 cause of these differences.
22 Again, it's unfortunate that Westinghouse did 23 not take this opportunity to test their prediction of 24 friction losses under single and two-phase conditions with (m,)
25 the data obtained at OSU.
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346 i
1 leaves one with a hollow feeling.
2 With respect to application of the code to s
l
)
3 the plant, Westinghouse claims that they have picked the 1
4 worst case scenarios.
To substantiate such a claim, I 5
think more needs to be done.
At the moment, today at 6
least, we were not told how the interplay between l
7 containment pressure and temperature affected the heat i
l 8
removal capability.
One dimensionless group one could use l
9 for this, for example, is the Jacob number.
10 Finally, I think that GOTHIC is going to 11 provide the boundary conditions for WCOBRA/ TRAC.
And the 12 uncertainties that we have with the GOTHIC code is going 13 to affect our cloud of fidelity of WCOBRA/ TRAC r~h i
\\m/
14 predictions.
15 CHAIRMAN KRESS:
Go ahead.
Yes?
16 MR. ZUBER:
I have one more.
17 CHAIRMAN KRESS:
Yes.
You go right ahead.
18 MR. ZUBER:
I would like to add something I 19 forgot to say.
I think I would urge both Westinghouse and 20 the staff, both at NRR and RES, to obtain and establish an 21 effective dialogue and cooperation between the groups 22 working with the containment and the reactor system.
I 23 think for this type of plant, I think this is essential.
24 By having it in two differing groups not
(~b (j
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1 designed is asking for prob 3 ems which are unnecessary.
I think maybe your Committee could really address this l
2 N',]
3 question and urge the staff to obtain this cooperation.
4 It was always my impression while I was still 5
in NRC and sitting through this meeting, there was never 6
really a good dialogue established.
I think this is 7
because the organization fines people.
But I think this 8
kind of system requires close cooperation.
I think this 9
way we could save money and obtain better results.
10 CHAIRMAN KRESS:
Are you through V.
J.?
I 11 guess at this time I'll invite comments from the other 12 members.
13 MR. LEVIN:
Mr. Chairman?
\\w 14 CHAIRMAN KRESS:
Staff is welcome to comment.
15 MR. LEVIN:
This is Alan Levin from NRR.
16 Responding to Dr. Zuber's last comment, we 17 are vitally aware of the need for good coordination with 18 the containment review, for the passive plants 19 particularly.
And we are taking the steps that we need to 20 do to make sure there is a continuing dialogue and 21 awareness of the state of the containment code reviews and 22 model there, both NRR and we have asked Research for their 23 help as well.
24 MR. ZUBER:
That's very gratifying.
/"N(
25 CHAIRMAN KRESS:
Good to hear.
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Comments, Bob?
2 MEMBER SEALE:
Well, I think they've said
)
,. s
(
)
'~'
3 pretty much everything I would think appropriate at this 4
time except I'd like to add one other comment to the 5
question about containment.
6 Somewhere down the road I think it would be j
7 nice to know whether or not everyone has convinced 8
themselves that thin steel shell containments, which have 9
been notoriously deceitful in the past and treacherous in 10 some cases, can really be reliably applied in this case, 11 the case you're talking about here, because I understand 12 there have been some real problems with tracking on those 13 things.
So as you look down the road, that would be a (D
/
14 question to address.
15 CHAIRMAN KRESS:
That's another issue you're i
16 l
17 MEMBER SEALE:
It's another issue, but it's 1
18 kind of square one as far as this other application is 19 concerned.
20 MR. CATTON:
Different subcommittee.
21 MEMBER SEALE:
Well, but --
l 22 MR. ZUBER:
The reactor does not know l
23 organizational --
24 MEMBER SEALE:
Unfortunately, it all r~s 25 integrates when it gets here.
()
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349 I
1 CHAIRMAN KRESS:
Mario?
2 MEMBER FONTANA:
Well, most of the questions
,s
(
)
l 3
that I had before I came in here have been answered.
One 4
thing that comes to mind is more philosophical.
It looks 5
like the AP600 missed an opportunity, could have avoided 6
excessive dependence on precedent and built a case from 7
scratch that would have been more useful in the future.
8 It might be neither here nor there.
9 It also appears that the code that's being 10 used is too detailed for the application.
It's kind of 11 like using a sledgehammer to drive a tack.
I wonder if it 12 would have been easier from scratch to start with a new 13 code.
(3
\\
l
%- /
14 One thing that comes to mind, if you insist 15 on using this code, it may have been less expensive to go 16 ahead and buy a work station, put it in an empty office, 17 and go ahead and let it run for 200 days, then come back 18 and say, "I told you so."
19 So that's the -- as I said, most of the 20 questions I have had been answered.
So I don't have any 21 more to say.
22 CHAIRMAN KRESS:
Well, I don't have a whole 23 lot to add.
I do agree with most of the comments that l
24 were made by the consultants.
I might want to expand a q(j 25 little on a couple of them.
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i 350 l
1 One, I recall a comment that Ivan made l
2 earlier that the temperature of the feedwater coming from
,,s 8
t
~
3 the IRWST or the sump could depend very much on whether 4
it's stratified or not.
And the timing which that hot 5
slug reaches is a function of the stratification.
And 6
that could be an important issue that I don't see was very 7
well-covered by the sensitivity analysis.
I think it's an 8
issue that you need to look at a little closer.
9 MR. CATTON:
Tom, here they should treat in 10 order to deal with --
11 CHAIRMAN KRESS:
They should deal with them 12 separately.
13 MR. CATTON:
Pressure and temperature need to rx 14 be separated.
~-
15 CHAIRMAN KRESS:
Yes.
And I started to say a 16 good way to do that would be a Monte Carlo-like 17 sensitivity analysis, just throwing the containment away 18 and using inputs that were developed from GOTHIC in terms of ranges and so forth.
But most of the guys didn't like 20 that.
I think it would be doable and would be very i
21 helpful to me.
22 Another comment that I was looking for l
23 answers for before I got here and I'm not sure I really 24 got was that the thing that could affect the level in the r~T i,)
25 core to me was mostly a question of balance of flow coming s
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351 1
in, steam going out, and the energy added to this.
And l
2 energy added came from the core decay heat and from the 7~
~
3 downcomer.
4 And I didn't see where you were actually 5
adding energy from the upper plenum and the exit piping.
6 And I suspect the time constants for those regions are 7
different than the time constants for the downcomer.
And 8
the energy storage content is different.
9 I didn't see a good -- yes, I was told that 10 these weren't important compared to the downcomer, but I 11 wasn't convinced.
So I needed more.
I needed to see more 12 like:
What is the energy content of this?
How hot do 13 they get over the whole transient?
What are their time O
's/
14 constants?
And how does this really affect it?
15 So from the same standpoint, if I had seen 16 time constants tabulated for different parts, that would 17 have helped me a lot.
So that's something in the future.
18 I would have liked to have seen these time constants for 19 the different areas.
20 Other than that, that's all the additional 21 comments I have.
I guess we can -- what I intend to do is 22 summarize this meeting to the full Committee and try to do 23 it justice.
Other than that, I don't know what else to 24 say about it.
/~ N.
(,)
25 MR. CATTON:
Are you going to ask us for NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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1 reports?
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2 CHAIRMAN KRESS:
Yes.
And it would be great
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3 if I could get a report before I have to summarize this 4
stuff next week.
5 MEMBER SEALE:
Could we ask Novak if these 6
guys are able to arrange something where you might 7
involved in that other containment thing, could you let 8
Tom know before if possible or let Paul know, I guess?
9 That would be worthwhile.
The rest of the Committee would 10 be interested to know what the possibilities look like in 11 that direction, I think.
12 CHAIRMAN KRESS:
With that, I think I'll ask 13 the staff if they have one last comment they want to make.
f3
(_)
14 Do you?
15 MR. LEVIN:
I'll make one final comment.
In 16 listening to the members' and the consultants' statements, 17 the main reason that we encouraged Westinghouse to come in 18 here on this was to get the ACRS to hear what they have 19 done in terms of the windows approach compared to about a 20 year ago, when we first met about this and discussed it in 21 detail.
22 At that time the Subcommittee and consultants 23 expressed a great degree of skepticism about the ability 24 of this methodology to do the job.
And the staff also had
()
25 a fair degree of skepticism, I think.
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As time has gone along here and Westinghouse 2
has begun to produce some results and has linked the 73
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3 windows out from their original 1,000 seconds or so to 4
something a little longer than that, been able to 5
demonstrate a little more consistency, I think we're all 6
pretty much on the same page with the Subcommittee.
There 7
are some questions that still need to be answered, but we 8
think that the approach probably is viable in terms of 9
what Westinghouse was trying to accomplish.
10 CRAIRMAN KRESS:
Thank you.
11 MR. CATTON:
I think the concern that we 12 expressed in the past was not so much that it's viable but 13 that it was dumb.
And it was dumb in the sense that it's N/
14 so costly to do the calculations that you're going to 15 reduce the number of calculations that you might do.
16 So that what happens is you reallv don't 17 properly explore the parameter space that you should.
And 18 you'll make arguments about conservative and bounding and 19 all of these other things where if you would have taken l
20 right from the outset this quasi-steady or, as Tom likes 21 to say, steady state approach, you could have beat the 22 problem up and have presented a much more convincing case.
23 But, again, that's Westinghouse's decision, not ours.
24 MR. McINTYRE:
I think this is what we're l
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25 doing right now.
It's what we do every time we talk about NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS j
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this.
And I think we've talked about why we did that and l
2 you understand the why we're doing it the way --
73 i
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3 MR. CATTON:
I heard everything you said, and 4
I still think it's dumb.
But that's my own opinion.
5 CHAIRMAN KRESS:
Yes.
But it is our job 6
mostly to respond as to whether it's sufficient and j
7 adequate what you're doing.
8 MR. McINTYRE:
That's right.
It may be 9
sufficient and adequate, Mr. Chairman, is exactly what l
10 we're looking for.
11 CHAIRMAN KRESS:
I think that's what we will 12 focus on also.
l l
13 MR. ZUBER:
What you provided from last time, i
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14 you had all these data, experimental, to show this is 15 really flat and steady, something.
So we should have l
16 enough data now to really say that it's okay.
It's not l
17 elegant.
It's probably dumb, definitely dumb, but it's l
18 possible.
l l
19 MR. CATTON:
It will do the job.
l 20 MR. McINTYRE:
Possible.
That's fine, too, i
21 Novak.
I'll take that.
l 22 MR. CATTON:
I don't think there's any 23 question it will do the job.
24 CHAIRMAN KRESS:
I now declare this meeting
(-
()
25 adjourned.
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1 (Whereupon, the foregoing matter was 2
concluded at 5:27 p.m.)
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l NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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CERTIFICATE This is to certify that the attached I
proceedings before the United States Nuclear Regulatory Commission in the matter of:
Name of Proceeding: ACRS SUBCOMMITTEE ON THERMAL HYDRAULIC PHENOMENA (OPEN SESSION)
Docket Number: N/A Place of Proceeding: ROCKVILLE, MARYLAND were held as herein appears, and that this is the original transcript thereof for the file of the United States Nuclear Regulatory Commission taken by me and, thereafter reduced to v
typewriting by me or under the direction of the court reporting company, and that the transcript is a true and accurate record of the foregoing proceedings.
fr7 1A1/4 -
kCOR' BET'T ftIN'ER official Reporter Neal R. Gross and Co.,
Inc.
O NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 R1IODE ISLAND AVENUE, NW (202)234-4433 WASil!NOTON,D.C. 20005 (202)234-4433
INTRODUCTORY STATEMENT BY THE CHAIRMAN OF THE THERMAL HYDRAULIC PHENOMENA SUBCOMMITTEE 11545 ROCKVILLE PIKE, ROOM T-2B3 ROCKVILLE, MARYLAND MARCH 28, 1997 The meeting will now come to order.
This is a meeting of the ACRS Subcommittee on Thermal Hydraulic Phenomena.
I am Thomas Kress, Chairman of the Subcommittee.
'The ACRS Members in attendance are:
Mario Fontana and Robert Seale. ACRS Consultants in attendance are Ivan Catton, "V.J." Dhir, and Novak Zuber.
The purpose of this meeting is for the Subcommittee to continue its review of the Westinghouse Test and ' Analysis Program being conducted in support of AP600 design certification.
For this meeting, the Subcommittee will hear presentations from Westinghouse on the use of the WCOBRA/ TRAC code for calculation of AP600 long-term cooling performance.
The Subcommittee will gather information, analyze relevant issues. and facts, and formulate proposed positions and actions as appropriate, for deliberation by the full Committee.
O--
Paul Boehnert is the Cognizant ACRS Staff Engineer for this meeting.
Notice of this meeting was previously published in the Federal Register _on March 10, 1997 With the exception of this opening session and the last two sessions of this afternoon, this meeting will be closed to the public to discuss Westinghouse proprietary information.
A transcript of the meeting is being kept.
It is requested that the speakers first identify themselves and speak with sufficient clarity and volume so that they can be readily heard.
We have received no written comments or requests for time to make oral statements from members of the public.
(Chairman's Comments - if any)
We will proceed with the meeting, IN CLOSED SESSION, and I call upon Dr. Larry Hochreiter of the Westinghouse Electric Corporation to begin.
O
7 O
O O'
r NRR STAFF PRESENTATION TO THE ACRS t
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SUBJECT:
AP600: WCOBRA/ TRAC Validation and Verification for Long Term Coohng i
DATE:
March 28,1997 PRESENTER:
Lambros Lois
.V i
PRESENTER'S TITLE:
Sr. Nuclear Engineer Reactor Systems Branch Division of Systems Safety and Analysis Office of Nuclear Reactor Regulation i
i PRESENTER'S TEL. NO.: (301) 415-3233 1
1 i
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AP600: LONG TERM COOLING WCOBRA/ TRAC Validation and Verification Based on the Results of OSU Experiments Under Review: the " Windows" Approach Criterion: Core Coverage (Latest RAI Response 3/12.
Minor Outstanding Questions)
RELAP5/ MOD 3 Confirmed Quasi-steady state nature O
of the transient Questions Asked:
- Does WCOBRA/ TRAC Provide the correct solution? (vs OSU) l
- Is the Solution Conservative for AP600?
- Is the Solution Analytically Stable?
- Is the Range of Experiments Adequate?
O
O AP600: LONG TERM COOLlhG l
1 OTHER ISSUES Oscillations in the OSU Experiments, Potential Oscillations in AP600 Flooding. of Dead Spaces Containment Interface O
(Containment reviewed by SCSB?
Robustness of Data Base PIRT: Acceptable
" Appendix K" use of WCOBRA/ TRAC O
.