ML20151J454
| ML20151J454 | |
| Person / Time | |
|---|---|
| Issue date: | 07/29/1997 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | |
| References | |
| ACRS-T-3006, NUDOCS 9708050155 | |
| Download: ML20151J454 (67) | |
Text
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Official Transcript o N [
oceedings
~$0Q(p
) NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards Thermal Hydraulic Phenomena Subcommittee
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RETURN ORIGINAL Docket Number: (not applicable) TO BJWHITE M/S T-2E26 415-7130 THANKS!
Location: Rockville, Maryland 1
Date: Tuesday, July 29,1997
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[ote ufe of the Committee Work Order No.: NRC-1188 DPEN: eases 1-48 '
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Official Transcript o ocesdings 4
1 . NUCLEAR REGULATORY COMMISSION
Title:
Advisory Committee on Reactor Safeguards Thermal Hydraulic Phenomena Subcommittee f
TRO4 (ACRS)
RETURN ORIGINAL
- Docket Number: (not applicable) hS IE 415-7130 THANKS1
. Location: Rockville, Maryland
-Date: Tuesday, July 29,1997 .
gas yfECopy-Re 1
[oie le of ti~ef,or;y.4 ee .
Work Order No.: NRC-1188
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DPEN: eages 1-48 classeliPP 49 2&9 NEAL R. GROSS AND CO., INC.
. Court Reporters and Transcribers -
1323 Rhode Island Avenue, N.W. - -- -
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PUBLIC NOTICE-BY THE
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'a UNITED STATES NUCLEAR' REGULATORY COMMISSION'S ADVISORY COMMITTEE ON REACTOR SAFEGUARDS i.
- l. ' JULY 29, 1997 I I
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The contents of this- transcript of the
- proceedings of the United States Nuclear Regulatory f:
. Commission's Advisory Committee on Reactor Safeguards on JULY l
'\
29, 1997, as reported herein, is a record of the-discussions i
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I recordad at the meeting held on the above date.
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This transcript has not been reviewed, corrected i
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NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RilODEISLAND AVENUE,NW
. (202)234-443 L WAS!!!NOTON,D.C. 20005 (202)234-4433
__ _ - _ . . _ _ . _. _ __ __, ..,_.c_.. _ . - _ - .
Il 1 UNITED STATES OF AMERICA
, 2 + + +++
3 NUCLEAR REGULATORY COMMISSION 4 + + +++
5 MEETING 6 + + +++
7 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 8 THERMAL HYDRAULIC PHENOMENON SUBCOMMITTEE 9 + + +++
10 OPEN SESSION 11 + + +++
12 TUESDAY, 13 JULY 29, 1997 l'h
(,) 14 + + ++ +
15 ROCKVILLE, MARYLAND 16 + + +++
17 The subcommittee met at the Nuclear Regulatory 18 Commission, Two White Flint North, Room T2B3, 11545 19 Rockville Pike, at 8:30 a.m., Thomas S. Kress, Chairman, 20 presiding.
21 22 PRESENT:
23 COMMITTEE MEMBERS 24 THOMAS S. KRESS, Chairman
(,,,') 25 MARIO FONTANA, Member v
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i 2
1 ACRS STAFF 2 SAM DURAISWAMY 3 RICHARD P. SAVIO 4 PAUL BOEHNERT 5 MEDHAT M. El-ZEFTAWY 6 AMARJIT SINGH 7
8 ACRS CONSULTANTS PRESENT:
9 10 IVAN CATTON 11 VIRGIL SCHROCK 12 13 ALSO PRESENT:
,m i
'v') 14 Ralph Landry 15 Bill Huffman 16 Earl Novendstern 17 Bob Kemper 18 Brian McInyre 19 Mike Young 20 Andy Gagnon 21 Jim Lyons 22 Ted Quay 23 24 t' 3
(.) 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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3 1 A-G-E-N-D-A h 2 AGENDA ITEM PAGE J w o 3 Introduction by Chairman Kress 4 4 NRR Introductory Comments, R. Landry 6 5 Westinghouse Trasentation, D. Novenstern 18 G
7 8
9 10 11 12 13
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U/ 14 15 16 17 18 19 20 21 22 23 24
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) 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE , N W.
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4 1 P-R-O-C-E-E-D-I-N-G-S 2 (8:35 a.m.)
3 CHAIRMAN KRESS: The meeting will now lease 4 come to order. This is a meeting of the ACRS Subcommittee 5 on Thermal Hydraulic Phenomena.
6 I'm Thomas Kress, Chairman of the 7 Subcommittee.
8 ACRS member in attendance is Mario Fontana and 9 we have ACRS consultants in attendance, Ivan Catton and 10 Virgil Schrock.
11 The purpose of this meeting is for the 12 subcommittee to begin its review of the application of the 13 Westinghouse (W) NOTRUMP small-break (SB) LOCA code to the 14 AP600 plant design. the subcommittee will gather 15 information, analyze relevant issues and facts, and 16 formulate proposed positions and actions as appropriate, 17 for deliberation by the full committee.
18 Paul Boehnert is the cognizant ACRS staff 19 engineer for this meeting.
20 Most of this meeting will be closed to the 21 public to discuss Westinghouse proprietary information, 22 and as has been noted on the agenda.
23 A transcript of the meeting is being kept so 24 it's requested that speakers first identify themselves and i i
1 25 speak with sufficient clarity and volume so that they can NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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5 l
1 be readily heard.
1 f~s 2 We have received no written comments or i i
'~'
3 requests for time to make oral statements from members of l 4 the public.
5 I have no introductory comments so I'll ask if 6 any of my fellow members or consultants want to make some 7 introduc.c>/ remarks before we start. Seeing none, I
]
8 guess I'll start out with Mr. Ralph Landry of the Office l 9 of Nuclear Regulatory Regulation to begin.
10 Ralph.
l 11 MR. LANDRY: Is that in a position that it's l
12 working?
13 I'm Ralph Landry, technical review staff of I
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' /
14 NRR, Reactor Systems Branch. With us today is also Bill 15 Huffman, one of the project managers from the 16 standardization project directorate at NRR.
17 We began our review of the NOTRUMP code in 18 approximately 1994. NOTRUMP is a 10 CFR 50, Appendix K 19 methodology code for analysis of small-break LOCAs. The 20 staff approved the NOTRUMP applicability to the operating 21 plants in 1985. The WCAP10079-P-A document describes the 22 code and its applicability to the current generation l
! 23 operating plants.
24 In 1994, Westinghouse came in with the code CN 25 applicability document for the AP600 design, and that is
( ,/
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6 1 WCAP14205.
I t
,- 2 DR. CATTON: Ralph, that approval in 1985, was
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l 3 that for small-break?
4 MR. LANDRY: That was for small-break LOCA 1 I
5 only. )
6 DR. CATTON: Now, the ACRS, as I recall, only 7 reviewed large-break. I don't believe they reviewed the 1
1 8 small break. .
l 9 MR. LANDRY: At that point, that may be true, l
10 Ivan. j i
11 DR. CATTON: Yes.
1 12 MR. LANDRY: The staff, in the review of the 13 documentation on NOTRUMP was assisted by INEL, currently p
14 it's INEEL. In the process of the review of the CAD, the l
15 staff and the contractor said that the CAD was woefully i 16 inadequate, I guess would be a way of couching the term.
17 The document was about a quarter of an inch thick and we 18 said this just does not adequately address the 19 applicability of this code to a reactor design.
20 In the process of reviewing the CAD and the 21 test analysis reports from the test program performed in 22 support of AP600, the staff and the contractor developed 23 104 .equests for additional information. We had many, l
24 mauf meetings with the applicant subsequently, discussed
(
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%j 25 wrat we expected to see in a final verification and NEAL R. GROSS COURT REPORTERS AND TRANSCRIF#AS 1323 RHODE ISLAND AVE., N W 9 02) 234-4433 WASHINGTON, D.C. 20005 370I (202) 234 4433
!! 7 1 validation report, which we received last fall in the REV
,-_s 2 0 version of WCAP14807. Aid our first look at the final
( )
3 V&V report resulted in another 46 RAIs.
4 So, you can see that material comes in. Staff 5 has reacted rather sharply and asking a lot more 6 questions, and asking for a lot of clarification. In the 7 process, we've asked 150 total RAIs on this code.
8 DR. CATTON: Ralph, I understand what makes a 9 large-break LOCA code an Appendix K code. But in reading 10 through all this documentation, I'm having a lot of 11 trouble figuring out why a particular small-break LOCA 12 code is called Appendix K. Can you help me?
13 MR. LANDRY: Let me do that tomorrow
(~%
k-m 14 afternoon, Ivan.
15 DR. CATTON: That's fine.
16 MR. LANDRY: Let me go through a little bit of 17 that tomorrow afternoon because in the staff's 18 supplemental draft SER, the SDSER, one of the things that 19 1 did was go through and look at the documents, NUREG-20 0737, and 0611, which set down the requirements for 21 satisfying the post-TMI lessons learned and also the l 22 requirements for a small-break LOCA analysis. And in the l
i i 23 SDSER, went through item by item and determined where the 24 code met or did not meet the requirements of those two
/~S 25 documents to satisfy Appendix K requirements for a small-()
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8 1 break LOCA analysis. ,
,s-2 So, if you can, let me put that off until
() 3 tomorrow afternoon and try to address the little bit of it 4 at that time.
5 DR. CATTON: I'm going to ask Westinghouse the 6 same question because in reading through these documents, 7 I found it very perplexing. You usually when you say 8 Appendix K, this means well, gee, I'm going to relax the 9 rigor a bit and I can be a bit sloppy because I'm so 10 conservative. And I just didn't see that when I went 11 through this.
12 MR. LANDRY: I don't see --
13 DR. CATTON: So I'll ask for the explanation
/ ~ ~. \
( ) I k_/ 14 from them, too.
15 MR. LANDRY: I don't see where the law says, 16 or where the regulation say you can relax and be a little 17 sloppy because --
18 DR. CATTON: Well, that's been the practice.
19 MR. LANDRY: I have a different perspective.
20 I don't see any words in there that allow me to relax the 21 requirements.
22 DR. CATTON: You can make up for rigor with 23 conservatism.
24 MR. LANDRY: Yes. Let me go through a little
/x l
(v ) 25 bit of that tomorrow.
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9 1 DR. CATTON: Good.
,- 2 MR. SCHROCK: I had a little trouble, Ralph, >
N) 3 in understanding the regulatory view of mixing up 4 evaluation model and best estimate model calculations of 5 the same phenomenon in the same code, which is what we're 6 doing in NOTRUMP for critical flow. In some places, the 7 break flow, that is, is presumably constrained by Appendix 8 K. Whereas, flow through deliberate breaks is not 9 constrained by Appendix K. I don't understand the 10 regulatory philosophy which permits this.
11 MR. LANDRY: Let me try to address that 12 because we had some very long discussions on that, Virgil, 13 with my own management and with former members of the
%l 14 Westinghouse staff. We talked about the philosophy of the 15 Appendix K critical flow requirements versus the flow 16 requirements or permissions, whatever term you want to 17 use, the correlations you can use for such things as the 18 ADS. We've gone through that argument extensively. Let 19 me make a mental note to try to talk about that a little 20 bit tomorrow afternoon.
21 MR. SCHROCK: Do you have a clear explanation 22 for it?
l l 23 MR. LANDRY: Let me try to address it. Not 24 commit to a clear explanation.
25 In looking at the NOTRUMP code, we've noted NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W (202) 234-4433 WASHINGTON, D C. 20005-3701 (202) 234-4433
10 1 that there are a number of extensions to models within the 7s 2 code, whether you want to call them extensions,
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3 enhancements, modifications, whatever the terminology.
4 But Westinghouse has modified specific hardware components 5 within the code to handle the AP600 hardware components l 6 such as the ADS, CMT, PRHR, IRWST, different reactor 7 coolant pumps.
8 They've also extended the phenomenological 9 models. Most heavily in the drift flux in two phase level 10 swell area but in a number of other models. In the 11 documentation which we reviewed, and one of the reasons we 12 came out with so many initial RAIs was going through the
,_ 13 test reports we found that,the CAD did not describe 18 I\ ') 14 phenomenological models which were changed in the code, or 15 enhanced in the code. It was through the test reports 16 that we fout.d that these models had been modified.
17 Eighteen models were modified. Three of those 18 modifications were subsequently dropped and termed not 19 necessary. However, if you read the final V&V report, 20 revision 2, you'll find that there's still 18 models 21 described because in the assessment process Westinghouse 22 further enhanced other models. So, we're still at 23 approximately 18 phenomenological models which were 24 enhanced or modified in the code.
(Q) 25 A year ago the staff prepared a supplemental NEAL R. GROSS i COURT HLPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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11 1 draft SER, the SDSER, in which the review of NOTRUMP l
,_s 2 identified 24 open items and six confirmatory items. We 1
)
'# 3 identified numerous model and code assessments which had 4 to be performed. And tomorrow afternoon I'll go through a 5 little more of the detail of those assessments which we 6 have iterated with Westinghouse on to have reperformed 7 reanalyses of some of the integral system test program 1
8 that were performed for the AP600. Reanalyses of some of 9 the separate effects tests. Analysis of benchmark tests 10 which we specified must be performed. And an extensive l
11 list of two phase level swell analyses which we felt had l l
l 12 to be performed to assess the two phase level swell model l 13 changes, e
\m / 14 At this point, the staff is in the process of 15 preparing the final safety evaluation report on the 16 NOTRUMP code. The sc'ledule is to have the FSER two 17 projects approximately the end of August, first of 18 September. That means it will not be available tot he 19 public for several weeks after. But our target date is to 20 provide the FSER to projects at the end of the summer.
21 Our gut reaction at this point is that the REV 22 2 of the final V&V report appears to be complete. In the 23 process of interacting with Westinghouse and all the 24 questions we've asked, all the responses we've received,
(~S 25 we feel that the REV 2, just from the cursory review so (w/)
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12 1 far, is a fairly complete document. Westinghouse has
,_s 2 responded to all of our concerns and provided extensive
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k l
3 documentation. We did not like the idea of having to 4 search through piles of documents to find answers to REIs, 5 so Westinghouse has incorporated all of the RAIs, all the 6 questions, all the responses, as a separate appendix to 7 the final V&V report. So that we've attempted to get a 8 complete document so that you can come in to the final V&V 9 report and have all of the answers in one document.
10 Now, you still may have to go through some of 11 the old references, the old reports, to find real 12 phenomenological models such as the description of McBeth 13 correlation, Henry Fauske, those type correlations.
(~
(/ 14 They're not in extreme detail in the final V&V.
15 The final V&V, we believe at this point is a 16 complete document and it does support the code. We are in 17 the process of reviewing it. The members of the committee 18 have the copies of it and it's a formidable document.
19 It's taking us an extensive amount of time to get through 20 this document. So, our goal, though, is to complete the 21 review and have the FSER the end of the summer.
22 DR. C?.TTON: In that I have complained about 23 documentation in the past, I have to agree with you. This 24 is probably the best set of documents that I've seen in D,
t, d 25 some time. But, the -- what's lacking is there's no tie RJ NEAL R. GROSS COURT REPORTERS AND TRANSCRlBERS l 1323 RHODE ISLAND AVE., N W (202) 234-4433 WASHINGTON. D C. 20005-3701 (202) 234-4433 1
13 1 in between the RAI and the text. So, where a question has 2 been asked and answered, you don't know it until you go 73
()
3 read the RAIs.
4 MR. LANDRY: Westinghouse --
5 DR. CATTON: It would be really helpful if 6 they would footnote the damn document so that you would 7 know when you're reading something because you wind up 8 going through it and saying this is wrong. That's wrong.
9 This is no damn good. But it's been addressed in an RAI ,
1 1
10 and probably fixed, and you don't know that unless you 11 read all of the RAIs.
12 MR. LANDRY: One of the things that we had 13 pressed Westinghouse for was a road map to do that sort of ,
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15 MR. NOVENDSTERN: This is Earl Novendstern.
l 16 To add to that, what we attempted to do is we put together l 17 a -- it's Appendix A, I believe, a road map which points 18 to the sections of text where things were incorrect in the 19 text, in the main body of the report, the things that were 20 lacking, we changed that text in REV 2. So, the text, to 21 our knowledge, should be correct.
1 22 DR. CATTON: Will I be able to track it, then?
l 23 Because where it really became kind of obvious was the 24 sudden dropping of the momentum flux terms. You went from O
( j)
~
25 one equation to the next. Not text. No nothing in
! NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS
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14 1 between. I found an RAI.
.s 2 MR. SCHROCK: More than that, it says that you
/ \
3 will find an explanation in Section 1.9 and I look at 4 Section 1.9 and it does not deal with this topic. So, I 5 was unable to find the justification for elimination of 6 those terms. I don't understand the motivation for 7 eliminating them. Is it that much of a saving in 8 computational effort to do that? A prejudgment that it's 9 categorically negligible throughout all AP600 analysis is 10 naive, in my view. Certainly there is no way any critical 11 flow event can be calculated correctly with the neglect of 12 those terms.
13 So, you need go into a little more explanation
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\- J 14 about that and some documentation, it seems to me, as to a 15 comparison _of some carefully considered results with and 16 without those terms. How do we arrive at the conclusion 17 that they are always negligible in the AP600? I don't 18 believe it.
19 MR. LANDRY: It's a lot of these kinds of 10 questions the staff is very interested in hearing.
21 Because you have to realize, we've been very close to the 22 code and the documentation from all the interactions going 23 back and forth with Westinghouse, trying to understand l
24 what they've done. We may read material also with other
(~%
j i
(_) 25 knowledge and pass it over. So, the comments that you NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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15 ,
l 1 make will be beneficial to us so that we can see, have we j
.x 2 left something out, too.
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l 3 DR. CATTON: You caught this particular issue i l
4 but the RAI response is kind of weak.
5 MR. LANDRY: We want to hear back and forth 6 your feedback, also, so that we can make sure that we have 7 our description adequately supported, too.
8 DR. CATTON: Don't you have to go back to 9 RELAP3 to get rid of the inertial terms?
10 MR. SCHROCK: You know, my first reading of it i
11 was kind of disastrous and I set it aside for several 12 days. Because I thought, Oh, God, how am I ever going to 13 figure out anything from this about what this code is.
( )
N/ 14 It's 13 years since I read the original documentation. I 15 don't have the original documentation side by side to look 16 at this stuff. I look at a description of the code 17 section and it doesn't even set forth all of the 18 conservation equations that are solved. It claims to have 19 non-equilibrium capability. It doesn't explain how. I 20 don't remember all of the details that were in NOTRUMP 21 that deal with all of these questions.
l 22 In the end, my second reading turned me around t
23 and I understood a whole lot of what was dore and I don't 24 think it's a disaster as I did on the first reading. But A
( ,) 25 I don't think it's good documentation and I wonder, does
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1
I 16 l l
1 there exist a separate version of NOTRUMP which is clearly )
,. s 2 documented somehow that's retrievable by your staff, by
/ T i /
3 the Westinghouse people, separate from the NOTRUMP version 4 that's used for other purposes?
5 MR. LANDRY: We have access to the old NOTRUMP 6 documentation. We still have that on file.
7 MR. SCHROCK: Do you have the equivalent 8 documentation for this new one? Are people then going to i 9 have to look at this report and try to sort out what are 10 the differences between these?
11 MR. LANDRY: There will have to be some of 12 that.
l l
13 MR. SCHROCK:
In reading the description of fm )
(_/ 14 the changes, there's not a clear picture as to what it had 15 been, why it had to be changed, what it is now, and what 16 is the difference in the result calculated for a critical 17 problem one way and the other. I couldn't put my hands 18 around that at all.
19 MR. LANDRY: Let's hear Westinghouse's 20 description the next two days, see if those answers are 21 given. And we'll go back and try to make sure that we 22 negotiate back and forth when the documentation is all l
23 thorough, which is the requirements.
24 Part of this rcview, we had the advantage of
. c f 25 having some very good support in the review. We had v
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17 1 assistance of Len Ward while he was still at INEL who was ,
i
- g. 2 one of the old authors of FLASH. So, one of the old bases l
( )
s
'} 3 for all these codes. We had the support of the ACRS in l
4 having Novak Zuber attend a number of our meetings, thanks l 5 to Ivan when he was the chairman of the subcommittee and i
6 Doctor Kress when he was committee chairman, allowed l 7 Doctor Zuber to attend some of our meetings. And the 1 l
8 feedback from these people was extremely beneficial in the i I
9 review of the material, the technical review of the model 10 changes. l l
11 Before I get down, stand down, today, there l 12 are two people who I want to take a chance to introduce.
13 Jim Lyons who is branch chief of the Reactor Systems i
th
- V 14 Branch at NRR, and Ted Quay who is the director of the 15 Standardization Project Directorate. So, we do have some 16 of NRR management in support today.
17 MEMBER FONTANA: Yes. Approximately how much 18 staff effort has gone into reviewing this code and how 19 much contractor effort, approximately?
20 MR. LANDRY: I've been nominally working ful.'.-
21 time on it for two years. There are other codes I'm 22 responsible for and other problems, inspection of work on
. 23 operating plants and some other work. But, it's pretty l
24 close to full-time.
,r8 t,
) 25 Contractor work, we have spent, if you want to NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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1 18 1 put it in terms of dollars, on this code, close to l
2 $200,000.00 in contractor support. So, that would be
\ )
! 3 equivalent to a little over a full contractor staff year,
' l I
4 full-time.
l
\
l 5 MEMBER FONTANA: Thanks.
l l
6 CHAIRMAN KRESS: Thank you, Ralph.
7 This leads us to the start of the Westinghouse l 8 presentation and so, I'll turn it over to Dr. Novendstern.
l 9 DR. CATTON: You just push all the buttons 10 until one works.
11 DR. NOVENDSTERN: I know. Every one of these 12 machines are different.
13 I am Earl Novendstern. I have been with
\p_/ 14 Westinghouse for -- associated with Westinghouse for 30 15 some odd years. I have most recently in the past three 16 years been leading the effort on the V&V of all the 17 Chapter 15 LOCA and non-LOCA codes, and also leading the 18 effort on the preparation of the SAR work.
19 What I wanted to do in this presentation is 20 give a very brief overview of some history, and I'll skip 21 over what Ralph has already gone over. I go over quickly.
22 DR. CATTON: You're not going to skip over our 23 discussion of Appendix K, right?
24 DR. NOVENDSTERN: We will be getting into
()
( ,) 25 Appendix K a little bit --
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i 19 1 DR. CATTON: What I'd like to hear is a l
g~ 2 discussion of what makes NOTRUMP Appendix K. And why do
( )
l 3 you call it Appendix K?
l 4 DR. NOVENDSTERN: That will be covered 5 primarily by Doctor Young. I'll go a little bit to the 6 philosophy of how we --
7 DR. CATTON: And he's next. Okay.
8 DR. NOVENDSTERN: He's next. It's going to be 9 part of the presentation.
10 We talked about the licensing history. I'll 11 briefly go over test facilities and the structure of the 12 report. This report is very voluminous, very large and 13 thorough.
/T
's-) 14 I wanted to initially refresh everyone on the 15 passive features of the AP600 design. And the passive 16 features which we'll be talking about a little bit later l
l 17 are the ADS, the automatic depressurization valves, ADS 1 l
18 through 4. The ADS 1 through 3 come off the pressurizer.
19 And I'm trying to look for 4 now. It's on the hot leg.
20 Here it is.
21 We have the CMT. We have the PRHR. We have 22 the IRWST. And, oh, the other significant difference 23 between this a.id an operating plant is the flow back into 24 the vessel equivalent to the ECCS flow is a direct vessel y-,
( ,) 25 injection as opposed to going into a loop.
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l 20 l
1 Very quickly, a typical or operating PWR fw 2 pressure transient for small-break looks like this where
/ )
~'
3 we have the break at zero. The reactor trip and that l 1
l 4 signal is coming around 1,700 psi. We reach a quantity, 5 steadies equilibrium, pressure for a period of time. Then ),
6 we continue depressurizer. The accumulators inject here 7 later in the transient and we'll compare AP600 and l
l 8 operating plants, and high pressure safety injection '
9 really starts and goes through the whole transient. We do 10 have core uncovery in operating-- in a lot of cperating I 11 plants. Not all. AP600 has lots of margin to core l
12 uncovery.
1 13 For AP600, we get the S-signal in around l
("')
i 1 l x- 14 1,700. Once we've started due to the gteam generator and 15 the PRHR performance, we start with natural circulation ,
1 l
l 16 and blow down. There is a phase which we will be 17 describing later. We've really lumped it and you will see l
18 later in the presentations a blow down natural circulation l 19 phase and then later on in the transient where we start 20 with ADS-1 firing, and ADS-1 fires at 67 and a half i
21 per.ent of CMT draining. The CMT initially has started 22 recirculating, then starts draining over this period of 23 time. ADS-2 fires 70 seconds later. And ADS-3 120 24 seconds later than ADS-1. They are on timers.
/
k ,g) 25 As we're draining the CMT, ADS-4 eventually NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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21 1 fires. That is opens on a 20 percent CMT level. When ADS l ,~s 2 fires, the biggest difference between this and current day
!(' )
'~
l 3 plants is we rapidly decrease the system pressure. We 4 event' Ily get into IRWST injection.
5 We have called the small-break LOCA and 6 evaluation we have done, is to the start of stable IRWST 7 injection. From that point on, we talk -- we go into a 8 long term cooling phase. We had a presentation before the 9 ACRS. I believe it was the end of March with COBRA / TRAC 10 where we had talked about the approach we used and the 11 windows modes.
12 DR. CATTON: These timers, how do they work?
13 What are they? Little electronic timers?
(_/ 14 DR. NOVENDSTERN: They're electronic timers.
15 There's a level signal at -- for ADS-1. And then there is 16 a timer --
17 DR. CATTON: The clock starts, 18 DR. NOVENDSTERN: The clock starts ticking, 19 really, and electronically through the I&C system, it will 20 open up the valves and send the signal 70 seconds or 120 21 seconds later.
22 DR. CATTON: What kind of reliability are you 23 going to ask of these timers?
24 DR. NOVENDSTERN: They're safety grade timers.
! (~'N l i, ) 25 DR. CATTON: That wasn't the question.
\
g ,-
t NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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l 22 i
l l 1 DR. NOVENDSTERN: I don't know much more about '
i
! f3 2 the details of the timers. Let me ask whether Bob Kemper l k) 3 or Brian McIntyre would know much more.
4 DR. CATTON: Are they like the ones I have in l
5 my kitchen stove, or what? ,
l 6 MR. McINTYRE: I think they're probably a step 7 above that. They're part of the control and protection 8 monitoring system. It's the same thing that controls the 9 rest of the safety functions.
10 DR. CATTON: See, when you look through, you 11 find that there's some evaluation of inadvertent actuation 12 of the ADS system. But there is no -- I didn' t see 13 anywhere any evaluation of a partial actuation of the ADS O
\- / 14 system. And what happens to you if 3 doesn't open, or 15 something, or maybe 4 doesn't open on the clock?
16 DR. NOVENDSTERN: Four is a pressure but let's 17 talk 2 and 3 are the ones which are timers.
18 MR. McINTYRE: I think for that you see the 19 PRA.
20 DR. CATTON: But don't you have to do the 21 thermal hydraulic evaluation to feed the PRA?
22 MR. McINTYRE: That's the thermal hydraulic 23 uncertainty and there are certain success criteria that l
l 24 are looked at as part of the PRA. You look at things l
<^x
( ,), 25 there on more of a best estimate basis.
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l 23 l 1 DR. CATTON: Do you actually pick a scenario 7, 2 and calculate your way through it?
, ( )
3 MR. McINTYRE: They have tried -- They have 4 picked --
5 DR. CATTON: Your people can't do thermal 6 hydraulics. George is not here to defend that.
7 So, you let your PRA people do the thermal 8 hydraulics? I'm not understanding you.
9 MR. McINTYRE: I haven't been able to finish 10 the sentence.
11 This is a question that the staff has come up 12 with and it was the thermal hydraulic uncertainty issue as 13 to whether or not our PRA was sufficiently robust, did 'e O
\~sl 14 have the right success criteria pick. What happens it ou 15 do have partial failures of things.
I 16 So they went through and they picked what were )
1 17 they thought the limiting success criteria for each of the 18 different types of scenarios that you could have. And 19 what we found was that we went back and looked at using 20 NOTRUMP, what the limiting -- the I guess how you describe 21 this. The certain PRA sequences were on the edge, low 22 margin, if you will. And so, we went back and did those 23 calculations. Because we had done most of the 24 calculations with NOTRUMP. Excuse me, with MAAP.
, /"~N l ( ,)
1 25 And we went back and looked at ones that were NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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24 1 tr.arginal using the NOTRUMP code showing that yes, they fx 2 were either, indeed they were okay. Didn't have a peak
(
)
3 clad temperature that it exceeded. I can't remember what 4 the limit was. I don't know if it was 1200 degrees or 2200 5 degrees because you're looking at a PRA in this case. Or, 6 they were over that and they should be considered 7 failures. But that's the whole purpose of this thermal 8 hydraulic uncertainty question.
9 The PRA people actually did talk to the 10 thermal hydraulic people for this.
11 DR. CATTON: Were there RAIs on this?
12 MR. McINTYRE: The thermal hydraulic 13 uncertainty report is in good Westinghouse tradition, one p- y
! i
(_ / 14 of those things--
15 DR. CATTON: Is it available here?
16 MR. McINTYRE: Yes.
17 DR. CATTON: Has it been given to the staff?
18 MR. McINTYRE: Yes.
19 DR. CATTON: Paul, could you get it for me?
20 MR. BOEHNERT: Sure.
21 MR. McINTYRE: It was turned in, I think it 22 was in, I think in June.
I 23 DR. CATTON: See, for PRA, you're supposed to 24 do best estimate calculations.
(D
( ,) 25 MR. McINTYRE: Yes sir.
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25 1 DR. CATTON: That's another reason that I'm
, ~s 2 interested in the difference and what the designation
\s) 3 Appendix K does to you.
4 DR. NOVENDSTERN: We'll be getting -- as we 5 get into the presentation, we'll be getting more into 6 that.
7 Shown here is a ccmparison of operating plants 8 versus AP600 on one graph. Let me first discuss the left-9 hand side showing pressure versus time. This is what we 10 had just discussed before.
11 The basic difference between AP600 and an 12 operating plant is AP600, as the ADS valves open, go down 13 to a significantly lower pressure. That significantly 1
\ 'i 14 lower pressure means you're not dumping out the break as 15 much liquid. There's also much more volume in the plant l 16 itself, water volume. When you look at the mixture level 17 above the top of the core, for AP600, we basically have l
l 18 lots of margin to the top of the core. There's over five l
l l 19 feet.
20 Typical of Westinghouse operating plants is we l
21 get to core uncovery and then core recovery. That's a 22 major difference. AP600 has lots and lots of water and 23 inventory, and it's very, very hard if not impossible, to 24 get it to uncover. One of the reasons which leads to --
(3
(_) 25 which addresses a question which was asked before with NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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l 26 1 regard to the ADS not being treated as with Appendix K l
7- 2 requirements and the greater flow requirements has to do 3 with the L -t that if you did treat the ADS valves with 4 Appendix K, you would get a better answer because you 5 would have greater -- you would depressurize even quicker.
6 Coming down quicker which would lead to a more non-7 conservative result.
8 DR. CATTON: Is that closer to truth?
9 DR. NOVENDSTERN: That's closer to truth.
10 DR. CATTON: I guess I'm just -- I don't 11 understand.
12 DR. NOVENDSTERN: Let me try going back.
13 MR. SCHROCK: You don't expect Appendix K to
,n
- v. 14 be close to the truth, do you?
15 DR. CATTON: No, but the fact that they don't 16 use Appendix K and they're further from truth, little I 17 bothersome.
l 18 DR. NOVENDSTERN: We use Appendix K for the l 19 break. For the ADS-1 through 3, we do not use Appendix K.
20 T2 we use Appendix K, we would get greater flow for a 21 given pressure out the system and more rapid 12 depressurization. That more rapid depressurization winds 23 up with AP600 performing better. It would be analogous to i
24 putting in larger valves in AP600.
- (v ) 25 DR. CATTON: See, break flow is not something NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE-, N W.
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27 1 I know a lot about. But I can look at the figures. And
,e 2 in one figure you see a gross under prediction. Gross.
3 Factor of 2 or 3. On another figure you see over 4 prediction. And then you find a common -- well, the net 5 result is reasonable.
6 In the past, we've called that compensating l
7 error. And I don't care whether it's because you put 8 Appendix K in one place and not in another. It seems to 9 me you should do something consistent.
10 DR. NOVENDSTERN: We will be getting into that 11 in a lot more detail in the subsequent presentations. We 12 recognize that is a difficulty and we'll be talking about 13 it more and why we treat it like that.
7~
f 4
'V 14 DR. CATTON: Would you agree with me that the 15 word is not misapplied? I'm talking about the integrated 16 mass loss through ADS-1 through 3. There are some cases 17 where it is a factor of 3 off.
18 DR. NOVENDSTERN: Yes.
19 DR. CATTON: That I would consider gross for 20 any code, including Appendix K.
21 DR. NOVENDSTERN: I would agree --
22 DR. CATTON: Good.
23 DR. NOVENDSTERN: -- that it is a factor of 3 24 off, p)
(v 25 DR. CATTON: Oh.
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28 DR. NOVENDSTERN: Let's not agree on the 1
2 wording. That is very subjective.
3 MR. SCHROCK: I still have trouble with how 4 you persuaded the staff that you're complying with the 5 law. If you claim you're doing an Appendix K evaluation 6 model calculation, it seems to me that it says clearly 7 thou shalt use the Moody model calculation for critical 8 discharge of the system. And you somehow have chosen to l have multiple breaks combined in different ways. You have l 9 10 a break which initiated the event and then you have breaks 11 which you create. And you say, we don't have to consider 12 these as breaks. That's -- to me, that's very -- and I think sets a preceaent in dealing with what is law. Which 13 14 is -- I'm not sure whether that's good or bad but I think 15 it deserves a considerable amount of consideration to 16 answer that question. Personally, I view Appendix K as an 17 unfortunate fact of life in 1997.
18 DR. NOVENDSTERN: Yes.
19 MR. SCHROCK: We've argued that exhaustively.
20 But we have it and it's an option that you have to pursue.
21 But I don't think you're pursing it according to the 22 letter of the law.
23 The staff is evidently agreeing with you that 24 it's okay because if you didn' t do it that way, the 25 nonsense of Appendix K becomes very obvious and you are NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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29 1 very clearly aiding your argument that the thing is safe.
,y 2 Because you charged more than really you're going to do.
I 1 3 DR. NOVENDSTERN: That's correct. That's, as 4 you said, the nonsense --
5 MR. SCHROCK: That doesn't solve, in my mind, 6 any aspect of are you or are you not presenting a 7 calculation which is a clearly defined Appendix K 8 calculation. I think you're not.
9 DR. NOVENDSTERN: One could debate that and 10 the NRC --
11 MR. SCHROCK: What is the argument in this 1
12 debate. An intentional break was not the intent of the l 13 law, that's essentially what you have to be arguing. Have
? ?
\/ 14 you consulted the writers of Appendix K to find out what -
l 15 - It's written down in the law.
, 16 DR. NOVENDSTERN: I know. The other argument 1
j 17 is if we did the SAR calculations with Appendix K applied 1
18 to ADS, we clearly would have better results and we're l
l 19 presenting a conservative case by not using Appendix K.
20 Ralph?
l l
l 21 DR. CATTON: But in Appendix K, you're 22 supposed to pick the conditions that give the worse 23 result. That's the basis of Appendix K. And you're now 24 making the argument you don't want to do that. You want
())
(_ 25 to -- You're kind of half and half. The break you picked NEAL R. GROSS COURT REPORTERS AND TRANSChlBERS 1323 RHODE ISLAND AVE., N W.
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l 30 1 in the past, high break flow, was bad news because that 2 dip that you see there. In your case, it's the opposite.
rv w]
3 So, if you want to do an Appendix K evaluation, you should 4 reverse and pick what is worse for you as far as the break 5 is concerned. And you're not doing that. And I don't 6 understand that.
7 DR. NOVENDSTERN: Ralph, do you want to -- did 8 you want to say something and then let me add?
9 MR. LANDRY: Let me address this a little bit 10 more tomorrow, Virgil, as I said earlier. But this is not 11 setting the precedent for following this procedure. The 12 precedent was set with the BWRs where this was the same 13 procedure using automatic depressurization of BWRs.
1(\-)
l 14 That's part of the argument that we went I
15 through on the staff in why we would agree to this 16 process. The other part is what Earl has been alluding l
17 to. That it is more conservative to use a realistic break I l
18 flow for the ADS because it makes the transient worse as l l l l
19 far as lowering the core -- or, lowering the system l l
, 20 inventory. l 21 And our view was that we want to make the most 22 conservative calculation possible. If we have to use 4 23 Moody critical flow for the break and use something such 24 as Henry Fauske HEM flow for the ADS, and it gives us a
( ,)
t i 25 more conservative calculation, that that is what our goal NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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31 1 is.
2 You realize that this is mixing break
( )
3 calculations. We argued this on the staff considerably, 4 discussed this with Westinghouse. We've discussed it 5 philosophically with Westinghouse and former Westinghouse 6 staff, trying to understand why the ADS is not governed by 7 the Appendix K Moody critical flow requirements.
8 Let me just say at this point that we feel 9 this gives a more conservative calculation using more 10 realistic ADS flow. That was our goal.
11 DR. CATTON: But the problem, Ralph, is not --
12 is that the calculations they do to the ADS flow are way 13 off. They're not realistic. If you look at the figures p
(/ 14 that are in that volume, you find that the integrated mass 15 loss through ADS is way off. I mean, it's not a little 16 bit. We're not talking plus or minus 10, 20 percent.
17 We're talking factors of 3 in one case that I recall.
18 DR. NOVENDSTERN: Let me suggest --
19 DR. CATTON: Just a minute.
20 Now, what are you doing now? You're 21 compensating with a high break flow so that the net result 22 is near realistic. To me, that is compensating error and ;
23 compensating error has always been a no-no because we 24 don't know how to extrapolate it.
(m) b 25 MR. LANDRY: I would agree.
l NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W. l (202) 234 4433 WASHINGTON, D.C. 20005-3701 (202) 234-4433
32 1 DR. CATTON: I think it's just wrong. I don't
- 2 know what --
/si 3 MR. LANDRY: But Ivan, this is -- and Virgil.
4 This is why we had such a difficult argument on the staff.
5 Excuse me. I shouldn't say argument. Difficult 6 discussion among ourselves debating what is the proper 7 approach to take. And this has given us a lot of arguing 8 back and forth.
9 MR. SCHROCK: Well, I thought you were setting 10 precedents here but I think it's the most significant 11 thing you said in my mind is that the precedent already 12 existed.
13 MR. LANDRY: Virgil.
,y l \
(,/ 14 MR. SCHROCK: I didn't know about that 15 precedent.
16 Excuse me. I said that I thought the 17 precedent having been set by BWR example previously was 18 probably the most significant part of Ralph's answer to j 19 the question. l l
i 20 CHAIRMAN KRESS: Well, I think the purpose of l \
21 an Appendix K analysis is to end up with a robust design. l l
l 22 And if you follow the letter of the law of Appendix K, the l
l 23 intent is that it meets robust design. If you don't 1 24 follow the letter of law but depart from it in a
,a (u. ) 25 " conservative" manner, you still get a robust design. And NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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1 33 1 I think that's the bottom line. But then --
n 2 MR. SCHROCK: In my mind, the bottom line is f )
3 even a little lower down on the bottom. And that is here 4 is a very clear example of why it was a really major 5 mistake to continue with Appendix K as a licensing bassi 6 without qualifications on that.
7 CHAIRMAN KRESS: I agree with that statement, 8 yes.
9 DR. CATTON: And here, you don't know what to 10 do. On the one hand the estimates of the break flow in 11 their manmade break are very low. Appendix K is very 12 high. And tl.cy're going in the opposite directions. So, 13 how the hell do you know where robust is?
O 14 CHAIRMAN KRESS: Well, the way you know that 15 is you go to the PRA and look at the uncertainty analysis 16 in the PRA. But we haven't had a chance to review that 17 yet.
18 DR. CATTON: But I'm not sure the PRA will 19 deal very well with factors of 3.
20 CHAIRMAN KRESS: If it has a good uncertainty 21 analysis it should.
22 DR. CATTON: Maybe. It depends on how well 23 tuey do it.
! 24 CHAIRMAN KRESS: But that's the only way n
, ,s. j 25 you're going to know. The answer to your question, I NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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34 1 think, is to turn to a PRA and see what the total effect 7m 2 on the whole plant risk status is.
- \
3 DR. CATTON: I don't know why Westinghouse 4 wasn't just told fix the flow model so that you get at 5 least somewhere near your experiment. It's not often you 6 see results so bad.
7 DR. NOVENDSTERN: Let's -- Fe're going to be 8 discussing that and some of the deficiencies. We 9 recognize there are some deficiencies in the code. We're 10 going to be discusaing that, u.w they are treat ed and 11 dealt with. We recognize the It wasn't something which 12 was ignored and not dealt with. And you'11 be hearing 13 that in subsequent presentations.
n I l
's _/ 14 DR. CATTON: Sure ' a't dealt with in the text 15 that discusses it. If I wouldn't have looked at the 16 figures, I wouldn't have known.
17 CHAIRMAL KRESS: Wall, we'11 see if it comes 18 out later.
19 DR. NOVENDSTERN: We'll see.
23 MR. S". ROCK: Earl, the descript..on of the 21 model, Henry Fauske HEM, is puzzling to me. The Henry 22 Fauske model deals with something different from HEM. So, j 23 if it is homogeneous e<ailibrium, Henry and Fauske were 24 not the inventors of . .mogeneous equilibrium. And so, f7
) 25 it's a misnomer in that respect. If it's something other NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS l 1323 RHODE ISLAND AVE., N.W.
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i 35 l
1 than homogenous equilibrium, I hope somebody will explain l
lrx 2 why the model that's in there, which I can't find l 3 described in the document, is title Henry Fauske/ HEM.
1 4 DR. NOVENDSTERN: Mike, do you want to address l
l 5 that part of your presentation? .
I 6 DR. YOUNG: I can address that in my 7 presentation.
8 DR. NOVENDSTERN: Want to address it now?
9 DR. YOUNG: Or now. It doesn't matter.
10 DR. NOVENDSTERN: What would you prefer?
11 MR. SCHROCK: I don't care.
12 DR. NOVENDSTERN: Let's do it as part of the 13 presentation. It will be more logical.
I\ ')' 14 Back when we started on the small-break LOCA 15 efforts, and doing the predictions, we selected NOTRUMP in 16 part because it was used for operating plants. It was the 17 only code we really had available at that time.
18 COBRA / TRAK, best estimate, was in the process of being 19 developed. It was not even licensed at that time.
20 NOTRUMP has an emphasis on a more realistic representation 21 to address the TMI concerns. We tried to get it to 2 ?. predict as well as we can and then we apply Appendix K 23 conservatisms.
l l 24 Ralph talked about this. It's been used for a
! r^'
(N),
25 long time. Another reason it was selected, we recognize NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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36 that Appendix K conservatisms do penalize the design but 1
1 I
r_s 2 there was so much margin in the design that we could live
\
l
)
l
\
l 3 with that penalty. :
4 NRC review clearly was needed. The major i
5 enhancements we had were needed to get the code to run '
l I
6 reliably and meaningfully as low pressure applications.
1 7 Where density changes betveen liquid and gas are l 8 significant, we added models for the passive features, 9 CMT, ADS, et cetera. And the NRC clearly a review is l 10 needed because it's a new type of a plant. A passive 11 plant is a differen* PWR.
l 12 As Ralph said, we've had lots and lots of l 13 dialogue, both with the NRC, its reviewers, and Novak has rm l )
\J 14 attended a number of meetings. He's been very useful.
15 His feedback. He got us to do in some cases significant 16 additional work.
17 There was -- Here we're talking about Novak 18 again. We talked very briefly about this. It was 19 probably a half an hour and it got lost in the main 20 presentation when we were talking about testing, about 21 testing and codes, back in May of 1995 with the ACRS.
22 There was significant testing done l 23 specifically for AP600. We had separate effects tests for 24 core make up tank and ADS. Descriptions are here. I'm r"N
( ) 25 not going to go over them because they've been discussed l NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLi 'D AVE., N W.
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r 37 1 in detail at numerous ACRS meetings, the last one being of
, 2 May of '96. There is the integral effects or systems
> )
3 tests, Oregon State University which is a quarter height 4 low pressure facility and SPES which is a full height full 5 pressure facility.
6 DR. CATTON: When you did calculations of the 7 ADS behavior to compare with separate effects tests, my 8 recollection is you coached it reasonably well?
9 DR. NOVENDSTERN: Yes. We'll be talking --
10 Mike Young will be talking about that.
11 DR. CATTON: I just wanted to establish that.
12 So, I'd like to hear an explanation, Mike, when you're up 13 here, as to why they do so badly in the comparisons with, l'hi C/ 14 I guess it's OSU.
15 DR. NOVENDSTERN: It's OSU. SPES is fairly 16 good.
17 DR. CATTON: I'd like to hear the reasons for 18 the difference.
19 DR. YOUNG: We'll be focusing on that.
20 DR. NOVENDSTERN: The other thing, the other 21 set of tests which were not run specifical]y for AP600 was 22 a series of level swell tests that came out of review with 23 the NRC, its reviewer. And Novak and everyone said that l
l I
24 Westinghouse needs to focus more on showing NOTRUMP and l 25 predict level swell reasonably well.
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38 1 We went back into existing tests which are 20
,_. 2 or 30 years old. There's a Westinghouse EPRI G-2 test
[
3 which is a 17 by 17 rod bundle. The Achilles tests run 4 over in the U.K. which was also a 60 heated rod bundle, 5 both boil off tests and GE small vessel depressurization.
6 We needed to do three because when we started looking at 7 these, all these tests have a certain difficulties in 8 interpreting aspects of all these tests.
I 9 Again, Mike Young will be talking a lot more 10 in detail about what we've done here.
i 11 DR. CATTON: In the report, quite a few pages 12 are devoted to horizontal flow drift flux. Horizontal l
l 13 flow drift flux, I mean, those are just -- those words f}
(~ > 14 shouldn't be together. I don't see anything here that l l
15 allows you to evaluate that modeling.
16 Mike, when you're up and talking about these l 17 things, I'd like you to focus a little bit on horizontal 18 flow drift flux.
19 DR. YOUNG: I will.
20 DR. CATTON: And I'd like to know if you 21 talked about this before when Zuber was present?
22 DR. YOUNG: Horizontal drift flux?
l l
l 23 DR. CATTON: Yes.
24 DR. YOUNG: I believe Novak was at a meeting -
/N
( ) 25 -
x_/
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l
39 1 DR. NOVENDSTERN: Yes, yes, we did.
s 2 DR. CATTON: And he didn't become apoplectic?
/ \
\ /
^'
3 DR. NOVENDSTERN: Not particularly. He was 4 more apoplectic on level swell.
5 DR. CATTON: I'm surprised.
6 DR. NOVENDSTERN: He was very apoplectic about l
7 that. l l
8 CHAIRMAN KRESS: Ivan, are you saying you l 9 can't get a relative flow velocity between the phases in 10 horizontal flow?
11 DR. CATTON: I didn't say that. Drift flux is 12 strictly bubble rise relative to flow. That's what it is.
13 CHAIRMAN KRESS: I thought it was more
!^\
\I 14 generally applied to relative velocities between the 15 phases?
16 DR. CATTON: No.
17 MR. SCHROCK: Well, it does have --
18 DR. CATTON: The result is relative velocity 19 between phases, but the basis is buoyancy.
20 MR. SCHROCK: There's the distribution 21 parameter which is responsible in part for the relative 22 velocity going to the integration over the profile of 23 velocity and void distribution. Profiles of those two 24 quantities lead to different average velocities of the two 8
(0
( ,) 25 phases. And so, the distribution parameter does contain NEAL R. GROSS COURT REPORTERS AND TRANSCR!BERS 1323 RHODE ISLAND AVE.. N W.
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40 1 some of the contribution to relative velocit.y, but i
g-~\ 2 distribution parameter cannot be the same in horizontal
)
'. \x/
l 3 flow as it is in vertical flow. Cause of the void 4 distribution is a system of forces which act in part in 5 different directions for those two flows. And to make the 6 claim that the distribution parameter is the same in 7 horizontal flow as in vertical flow is conceptually 8 incorrect. Quantitatively it may not be terrible because 9 distribution paritmeter ranges over such a small span 10 anyway. But I think that's a fortuitous result that gives l
11 you numbers that consistent with other things that are in l
12 the code are probably okay.
l 13 But conceptually it's wrong and to state it j
/,,T
\ )
x' 14 that way I think is kind of irresponsib3e at this point in l 15 time. It's just not possible for the distribution of void 16 to be the same in a horizontal flow and a vertical flow.
17 CHAIRMAN KRESS: Only unless the gravity 18 forces are not what causes this distribution difference, 19 if it's something other than gravity forces that causes 20 such a distribution.
21 MR. SCHROCK: Well, that's a question of 22 extent. Gravity is always present.
23 CHAIRMAN KRESS: It's always present.
l l 24 MR. SCHROCK: It's always present. And 1
(_) 25 gravity will always have an influence on the horizontal NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE , N W.
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41 l
1 flow. Whether or not its a large influence sufficiently
,- 2 large, let's say, to cause stratification is a different
' /
\~ } \
3 question then is it correct to argue that the distribution '
4 is the same in one or tl other. It cannot be the same. l 5 The gravit.y is never going to be absent.
6 CHAIRMAN KRESS: It's never going to go away.
l 7 That's correct. !
l 8 MR. SCHROCK: It's clearly unreasonable to i 1
1 9 argue that it's always going to be negligible in the l l
10 horizontal flow.
11 CHAIRMAN KRESS: You have to know when it's 12 negligible and it's not.
13 MR. SCHROCK: Right. Exactly. .But it's a
/m V
1 14 l
i question of degree, i 15 CHAIRMA.N KRESS: But I understand you to be 16 saying that it's possible to use the drift flux type of 17 relationship although it would be different for horizontal 18 flow than it would be for vertical. And that Ivan may be 19 overstating the case, that you shouldn't even use the word 20 horizontal flow and drift flux in the same sentence.
21 MR. SCHROCK: I agree with him. It was 22 invented for vertical flow and it's extension to 23 horizontal flow has always been a source of difficulty for l
l l
24 me philosophically. I think it's a mistake to describe (v ,) 25 this as drift flux in the sense that the drift flux was NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE , N.W.
(202) 234-4433 WASHINGTON, D C. 20005-3701 (202) 234-4433
42 1 originated in the context of vertical flow and especially l
2 the relative velocity that's associated with the buoyant (n) ,
3 force. Buoyant force has quite a different role in the 4 horizontal flow.
5 CHAIRMAN KRESS: It determines whether you're l 6 stratified.
1 l
7 DR. CATTON: In horizontal flow you -- it's 8 drag that if there's a difference in the velocity, it's 9 drag.
10 CHAIRMAN KRESS: It's drag. It has to drag 11 distribution, yes.
12 DR. CATTON: And so what happens is you have 13 them asymptotically approaching one another. And this is V) 14 the same kind of problem you deal with in aerosols. It's 15 exactly the same. If the bubbles are small enough, 16 they're actually the relative velocity goes to zip very 17 quickly and it's carried with the flow.
18 CHAIRMAN KRESS: Then you use homogenous 19 models.
20 DR. CATTON: It's very different. Now, if 21 it's a vertical flow, it's very different. I mean, you 22 have Stokes drag as a limiting velocity and you can i 23 calculate it. Everything's nice. You get slip. But all s 24 these words only apply to the vertical case, not to the l
,e n 25 l (v) horizontal. And when you wind up with a mixture, a phase '
1 NEAL R. GROSS I l
COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE , N W.
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I
43 1 mixture and it enters a pipe, and you want to figure out 2 how quickly it's going to separate out, that's a two 73 3 dimensional problem. In the vertical momentum equation, 4 you're treating the vapor. You've got forces. In the 5 horizontal direction, you've just got drag And you need 6 to put it together.
7 We did some interesting experiments with 8 bubbly flow in a porous media. And that slows everything 9 down so you can actually see it.
10 CHAIRMAN KRESS: I particularly had in mind, 11 Ivan, stratified horizontal flow. That would be a place 12 where you would expect --
13 DR. CATTON: But once it's stratified, it's a f~)
i 1
'xm/ 14 different kind of problem.
15 CHAIRMAN KRESS: Yes, but you could treat that 16 with drift flux like modeling.
17 DR. CATTON: What does drift flux mean if I 18 have a stratified flow?
19 CHAIRMAN KRESS: That just the same thing as 20 was in vertical. That there's a --
21 DR. CATTON: In vertical --
22 CHAIRMAN KRESS: -- difference in velocity --
23 DR. CATTON: In vertical, once all the vapor l
24 is above the liquid, drift flux has no meaning.
l
/~s (N/ ) 25 CHAIRMAN KRESS: I think you can still treat r
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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44
- 1 the interfacial forces and the -- You can treat it with i
, ~s 2 the same type of correlations.
t i i 1
l l
3 DR. CATTON: It's still drag and proportional l
4 to relative to the two velocities.
I 5 CHAIRMAN KRESS: Well, that's what drift flux 6 is, too.
7 But anyway, I share your concern about using 8 the same correlations for horizontal --
9 DR. CATTON: When you read it and the words 10 that are used in describing it, you have a hard time 11 accepting it at all and you wonder where the heck did 12 these guys come from that would do something like this.
13 And there is a credibility problem. When you put the 1 l
("~))
k- 14 report on the table, people have to think that you have 15 some technical competence. And I just wonder about it 16 when you use that kind of a description.
17 And some of the things that are reference for 18 horizontal flow really are dealing with vertical. The 19 slip velocity ratios are big numbers and if you have 20 bubbly flow, you don't see that. And the slip is going to 21 be very small, particularly in horizontal flow, because 22 there it's like an aerosol.
23 I just don't see any of this kind of technical 24 understanding in what's being written. It may well be. I i <~x
( j}
/
r 25 mean, you can hammer anything to fit most anything if you NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.
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I 45 I 1 put enough parameters in it. I agree with that view. But l
l fx 2 if that's what you're going to do, you ought to say it and
! ( )
~
3 don't lead the reader down this garden path.
l l 4 Enough preaching.
l l 5 DR. NOVENDSTERN: Let me go on to the l
6 organization of the NOTRUMP validation report. And 7 basically things are driven by the PIRT. We talk about 8 the model improvements. The description is in Chapter 2.
9 The benchmarks are in Chapter 3. Single effects 10 validation or separate validation, level swell, and there 11 are three tests which we talked about before, are Chapter 12 4, CMT and ADS.
13 The integral effects validation, OSU and SPES.
( \
\2 14 What we also did after we've really gone through this is 15 we tried to put everything together in code assessment and 16 overview. And that one wound up being in Chapter 1 where 17 we related it to the PIRT. We talk about areas of good 18 agreement. We talk about some of the -- we talk about the 19 deficiencies, the Appendix K application and how we're 20 going to deal with the deficiencies. It's recognize our 21 deficiencies.
22 Between the REIs and the DSER open items, 23 there are somewhere, as Ralph said, over 200 of them.
24 There are responses, a road map, where wa needed to. In
! r~N i ( ),,
25 REV 2, we went back and modified some af these sections NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISI AND AVE., N W.
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46 1 where it was appropriate and where the NRC and 2 Westinghouse agreed, and modified some of these sections
/~.ss i i
~# 3 to make it what we believe more readable. I heard the 4 comments before that maybe it's not complete enough even 5 though it's good documentation.
6 DR. CATTON: It is an improvement over what I 7 have read in the past.
8 DR. NOVENDSTERN: We very much appreciate 9 hearing that. It's very refreshing to hear that because 10 we think we've done a heck of a good job. It's a huge 11 report. It's three volumes, about a foot thick in total.
1 12 DR. CATTON: This kind of a diagram is very I l
13 helpful. Whj isn't something like this right in the '
(73j
(./ 14 beginning of your report?
15 DR. NOVENDSTERN: I recognize -- Why isn't it?
16 As we had the pressures of getting out the report and 17 that's not an excuse, but as you're putting together a 18 presentation and trying to understand how to present it to 19 an audience, this is what came up. I agree it's useful.
20 on hindsight it would have been nice to put it in the 21 report as well. But it's a good road map which we can use 22 here during this meeting.
23 MR. SCHROCK: Earl, I would really have liked 24 to have seen a clearer definition of what the model had
/~N been, why it wasn't good enough now for this application,
() 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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l 47 1 what the model was changed to, the comparison on some
,s 2 critically chosen examples of prediction, by the previous
. / i
~
' ') 3 model prediction, by the new model, and that isn't found 4 here.
5 DR. NOVENDSTERN: I hear that. We honestly 6 thought we did that. I think as Ralph said, it may be a 7 matter of being too close to it. We hope during the 8 presentations to bridge that gap.
9 MR. SCHROCK: That gap, okay.
10 DR. NOVENDSTERN: In summary, we have a new 11 plant design. It's passive. And the significant 12 difference with small-break LOCA is the low pressure.
13 That's driven us. We'll be spending a good part of the
(~~) l
'ws/ 14 next two days on the enhancements which were needed for l l
15 the lower pressure applications and the passive features, 1
16 and the extensive validation we have done, both integral 17 effects and separate effects tests.
1 18 And that ends my portion of the presentation. l l
19 Are there any other questions? We're going to be getting 20 into very mucn more technical detail with Mike Young and 21 Andy Gagnon as we go on.
22 With that, I turn it over to Mike.
23 CHAIRMAN KRE9S: I think at this time I need 24 to announce, according to our agenda, that we're going
/~'s t 25 into closed session and that anybody who is not approved Vl NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE , N W.
l (202) 234-4433 WASHINGTON. D C, 20005-3701 (202) 234 4433 l
1
48 1 to be here --
,_,s 2 DR. NOVENDSTERN: As I look around the room --
'/ \
s 3 CHAIRMAN KRESS: There's nobody here.
4 DR. NOVENDSTERN: I recognize everyone in the 5 room.
6 CHAIRMAN KRESS: As long as you recognize 7 everyone that's in the room, why we can leave it with l 8 that. !
i 9 (Whereupon, the meeting went into closed l 10 aession at 9:44 a.m.'
l 11 !
l l
12 ,
, l l
13 l
f~'b 4 l \. / 14 i
i 15 16 17 l
l 18 l
19 l 20 l
21 22 23 24 t'D/
i 25 N_/
NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N W.
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. _ _ _ ~ _ _ _ __ _ ___ _ . _ .. _ _ _ . . _ _ ___ .._... _ .__._ _ _ ._ _ _ - - ...__ . . _ . _ _ _ . . _ _ . _
i CERTIFICATE This is to' certify that the attached proceedings before the United States Nuclear Regulatory Commission in the matter of: [
Name of-Proceeding: ACRS SUBCOMMITTEE ON THERMAL HYDRAULIC PHENOMENA Docket Number: N/A ,
Place of Proceeding: ROCKVILLE, MARYLAND ,
j were held as herein appears, and that this is the original transcript thereof for the file of the United States Nuclear i i l Regulatory Commission taken by me and, thereafter reduced to 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.
. # 4&A
'C6RB'ETT'NINdR l Official Reporter l Neal R. Gross and Co., Inc.
I NEAL R. GROSS COURT REPORTERS ANDTRANSCRIBERS 1323 R!lODEISLAND AVENUE,NW (202)234-4433 WASil!NOTON, D.C. 20005 (202)234-4433
/
, -c l
/~
INTRODUCTORY STATEMENT BY THE CHAIRMAN OF THE THERMAL HYDRAULIC PHENOMENA SUBCOMMITTEE l
11545 ROCKVILLE PIKE, ROOM T-2B3 ROCKVILLE, MARYLAND JULY 29-30, 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 Member in attendance is Mario Fontana. ACRS Consultants in attendance are Ivan Catton and Virgil Schrock.
The purpose of this meeting is for the subcommittee to begin its review of the application of the Westinghouse (W) NOTRUMP small-break (SB) LOCA code to the AP600 plant design. The subcommittee will gather information, analyze relevant issues and facts, and formulate proposed positions and actions as appropriate, for deliberation by the full Committee. ,
Paul Boehnert is the Cognizant ACRS Staff Engineer for this meeting.
(~)'
%)
Most of this meeting will be closed to the public to discuss Westinghouse proprietary information, as so noted on the Agenda.
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 and I call upon Mr. Ralph Landry of the Office of Nuclear Reactor Regulation to begin.
! .'"N N,sE
i AP600 NOTRUMP !
ACRS/ THERMAL-HYDRAULIC SUBCOMMITTEE ,
I JULY 29/30,1997 Ralph R. Landry ,
i Reactor Systems Branch, DSSA/NRR i
___ _____ __.__ ______________ _______ _ ___ _ _ ___ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ . _ _________ ____t
O O O -
NOTRUMP SB LOCA CODE 10 CFR 50, Appendix K Methodology Approved by Staff in 1985 for Operating Reactors (WCAP-10079-P-A) i Applicability to AP600 Passive Design j (NCAP-14206)
Staff Assisted by INEL (INEEL) Developed 104 RAls ,
Final V&V Report (WCAP-14807) Resulted in 46 Additional RAls 2
_ __ ___a
O O O 1
l i
Code Models Extended to Handle AP600 Hardware
- ADS t
- CMT
- PRHR/lRWST ft
- RCP i i
Code Models Extended to Handle T/H Phenomena. !
- Drift Flux
- Two-phase Level Swell
- 18 models (three subsequently dropped)
. f t
, 3 i
L i
f i
t t
Staff SDSER on AP600 identified I i
- 24 Open items
- 6 Confinnatory items !
c Identified Numerous Model and Code Assessments to be Performed k
l l
- i t
I l
h I
I i
f 4
t i i l !
t I
O O O l
NOTRUMP SB LOCA Staff FSER in Preparation Final V&V, Revision 2 Contents
- Appears to be Complete
- All RAls included i i
3 i
I
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e r
Advisory Committee on Reactor Safeguards Thermal Hydraulic Phenomena Subcommittee July 28 & 30,1997 NOTRUMP validation l Earl H. Novendstern Westinghouse Electric Corporation (412) 374-4790 i
o -
o o; Introduction h
. AP600 vs. Operating Plant SBLOCA Behavior
. Licensing History Operating Plants AP600 ,
. Summary of Test Facilities
. Topical Report Structure i
4k ( ._
O O O l AP6DD vs. Operating Plant Behavior AP600 Passive Safety Features n
.. . \ -
qp ,ngn nx N **"
NWs s a w Sa"'"
[ pt s G v ' '
M "I 5 % M
/r f, ,
/c P N so n -
pun,. ,
onpartmert acc laage 3
...---..-.-.:----..----E '-I. -i . . ' .'
O
~
O O .
AP600 vs. Operating Plant Behavior (con't)
Typical PWR Small Break LOCA Pressure Transient 2500 g i HPSI =
i,,me.aio.
ACC (Intennettent) m 2000 7 C '.7 : "'
a 1500 r
.L. _ .
=
~y ~
--==. . ,
0 im V L.m m
E Accessueuteto.. SW 500 ~
l .nye a 0 ' ' '
0 500 1000 1500 2000 2500 3000 IlMf (S)
O O
~
O .
AP600 vs. Operating Plant Behavior (' con't)
AP600 Two inch Cold Leg SBLOCA Pressure Transient 2,500
" Natur rc ton l= Aost Rwsr '. =l LTc =
1 1 3 4 %
2,000
.----Tnp @ 33 sec.
.---- S" Sqnal 0 40 sec.
p l g CMT Dran
- l E ',
g Acc. Ing.
1,000 -
g IRWST Injecton
=
SM -
i 0
O 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 Time (Seconds)
I O O O .
AP600 vs. Operating Plant Behavior (con't)
Comparison of Pressure and Mixture Level Behavior 2,500 15 -
g ,
, i
- I yp .j . . _ _ _ _ _ _ _ _ _ - . --- --
$ 10 - '-
~ ~} - t E ., .. l l l
~*
- ' - y- - - - , ,, ,,,
gg , . . _ _ _. _ _ . _ - _ _ . _ _ . . _ - _
o $ t. ,
a i
, a '
- , e l i
g k-
--+-.
, ! j :1 D
g 1,000 '
l, --
g 8 l Top ur Corn Ehrvation l 0
-%. 'jl g t
g ; ! .
\
ij b T i
[l 500 l,
i s
2 (5) - - - - - -- '
, i l
f 9 I ! I i I
O ~~ ' '
O 500 1,000 (10) 1,500 2,000 2.500 3,000 0 500 1,000 1,500 2.000 2,500 3.000 Time (Seconds) Time (Seconds) p,ge n
0 O O i t
Licensing History - Operating Plants
. Used for Operating Plant Small Break LOCA
. Emphasis on More Realistic Representation to Address Post TMI Concerns
. Appendix K Conservatisms Applied l
. NRC Approval in '1985 for Operating Plants Evaluation Model and V& V (WCAP-10054-P-A)
Coding Documentation (WCAP-10079-P-A) i
. .,o
Licensing History - AP600
~.
h 7 t
. NRC Review Needed Because: ,
Enhancements Needed for Low Pressure Applications Specific Models for Passive Features Added Overall System transient Performance of New Type of Plant \
t 1
. Meaningful dialog'ue for over Three Years NRC andit's Consultants ACRS Consultant ACRS (May 1996) l'.ge N l
1
o O O .
NOTREMP Assessed with Extensive -
r Amount of Test Data i
2 Core Makeup Tank Full Height Facility K Height CMT Full Pressure and Temperature ;
ADS ADS 1-3 Valves & Sparger (Full Size) ]
Full Pressure and Temperature Level Swell Westinghouse /EPRI G12 17x17 Heated Rod Bundle Boil-Off UKAEA Achilles ; 69 Heated Rod Bundle Boil rc I GE Small Vessel De ressurifation Vessel Blowdown Oregon State University
~
% Height t (7 Break Sizes / Locations) Low (~400 psi) Pressure l SPES-2 Full Height l
(7 Break Sizes / Locations) Full Pressure j nin 9
~
0 0 O '
[
t Report Contains all Relevant Information i
WCAP-14807 Rev. 2 l
l PIRT I
I I I I I Model Single Integral Code R Ats im provem ents Effects System s Assessment DSER Ols Validation Vahdation & Overview (Appendix A)
(C h.1) l '
-l Description Level S well (3) k OSU
' PIRT Relationship Responses (Ch. 2) (Ch. 4) ,
(Ch. 8)
I I I I l Benchmarks CMT S P E S-2 Areas of Good Agreement Road-map (C h. 3) (C h. 6) (C h. 7) .
i i
I ADS Defliciencies (C h. 5) ('
l Appendix K Apphcation n .mc so
O O O -
t Summary
. AP600 New Type of PWR Passive Features
^
Low Pressure During SBLOCA
. Enhancements Needed to NOTRUMP
. Validated with ENtensive Amount of Test Data Integral Effects Tests Separate Effects Tests i
n .,yc i s
. _ ____ ___ _______ _- __ _______________ __ - _______ - _ _ _ _ _ _ _ _ _ - _ __ _ ______ _________ -_______-____________________-____ __________