ML20128A273

Summary of ACRS ECCS Subcommittee 850403 Meeting w/B&W,C-E, Westinghouse & Louisiana Power & Light in Washington,Dc Re Exxon ECCS Model Errors,Bart/Bash ECCS Codes & Resolution of TMI Item II.K.3.30

ML20128A273
Person / Time
Issue date:	04/10/1985
From:	Advisory Committee on Reactor Safeguards
To:	Advisory Committee on Reactor Safeguards
References
TASK-2.K.3.30, TASK-TM ACRS-2299, NUDOCS 8505240172
Download: ML20128A273 (18)

Text

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• • DATE ISSUED: 4/10/85 D'

E 2 ACRS ECCS SUBCOMMITTEE MEETING MINUTES APRIL 3, 1985 WASHINGTON, DC l i

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Purpose:

The purpose of the meeting was to discuss: (1) Exxon ECCS Model Errors; (2) the W BART/ BASH ECCS codes; (3) the resolution of TMI Item II.K.3.30

- revision of small break LOCA ECCS Evaluation Models; and, (4) the resolution of the RCP trip issues given a small break LOCA. (Note:

Item 4 was not discussed due to lack of time.)

Attendees: Principal meeting attendees included:

ACRS NRC D. Ward, Chairman R. Jones H. Etherington, Member D. Langford C. Michelson, Member N. Lauben G. Reed, Member S. Sun I. Catton, Consultant J. Guttmann V. Schrock, Consultant E. Throm T. Theofanous, Consultant B. Sheron C. Tien, Consultant P. Boehnert, Staff, DF0 Westinghouse M. Young Babcock & Wilcox W. Tauche J. Paljug Combustion Engineering Louisiana Power & Light

• G. Menzel J. Holman Meeting Highlights, Agreements and Requests -

1. R. Jones detailed the problems NRC has been having with the Exxon LOCA analyses. The problems include code and input errors, concern 8505240172 850410 PDR ACRS PDR t,1. ED 021GIlilL 2299 L2.

Certified By hb .

ECCS Meeting Minutes April 3, 1985 i

over use of certain factors in the heat transfer calculations and l the validity of using the H K(Z) curve (defines allowable core '

peaking factor as a function of core elevation) in the ENC model.

(Exxon assumed the E K(Z) curve applied to ENC fuel). The K(Z) error is significant in that it can impact power operations (derates,etc.). The Ginna and Kewaunee plants require immediate Staff action in order to allow start-up from refueling. In response to Mr. Etherington, Mr. Jones said there are some problems with LOCA analyses for mixed fuel cores, i.e., the T/H analysis is not a straight-forward set of affairs.

The Staff is still wrestling with the overall problem of assuring compliance with Appendix K in a manner that will not unfairly penalize the affected licensees. One action under consideration would be to grant a temporary exemption to Appendix K requirements to allow timely start-up of the above noted plants. The Subcommittee requested that NRR keep it informed regarding progress to resolution of this issue.

An ENC representative (J. Owsley) made a brief statement describing ENC's efforts to resolve the above concerns.

Dr. Sheron noted that E has recently discovered an error in their ECCS EM that results in a PCT penalty of M 80'F. Because of the code used in the analysis (BART), only a few y plants are affected.

Upon reanalysis, none of the affected plants exceed 2200 F PCT.

2. The y BART/ BASH EM code models were described by Mr. Young of Westinghouse. BART replaces the FLECHT correlation and the steam cooling model in the y EM. Figure 1 lists the principal features of the BART code. NRC has reviewed and approved BART for use in LOCA calculations.

7 ECCS Meeting Minutes April 3,1985 The BASH code is proposed for the y EM in order to eliminate the current inconsistency between BART and the E REFLOOD code calculated entrainment rate. BASH is a combination of the BART and NOTRUMP codes. NOTRUMP models the loop thermal hydraulics outside the core. BASH is a 1-D code designed to improve modeling of the reflood portion of the LB LOCA. Comparison of-BASH code calculations with applicable reflood data (Figure 2) shows that the code outputs tend to give oscillations (Figure 3). This issue is under discussion with the NRC Staff as part of the on-going acceptance review. Overall, the code results are conservative with respect to the test data.

3. S. Sun (NRC) overviewed the NRC review and approval of the BART code. The original BART code was approved in December 1983.

Subsequently, improvements to the code and its use in different plant types (UHI) has been approved or review is on-going (Figure 4). Dr. Catton suggested that comparisons De made between BART and TRAC code calculations.

D. Langford provided the status of the NRC review of the BASH code.

The Staff review required verification of BART/NOTRUMP (the BASH code components) for the regimes of interest for EM conditions.

Review tasks remaining include: (1) y explanation of large reflood oscillations noted above, (2) E documentation and formal submittals, (3) retiew of new NOTRUMP materials (i.e., revisions to the code) and (4) review of new and revised BASH submittals. An SER for BASH is targeted for late August 1985.

Additional discussion brougtit out the fact that N50% of the ~

Appendix K margin is at the discretion of the NRC Staff, i.e., only 50% of the margin is tied up in the Appendix K features.

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. ECCS Meeting Minutes April 3, 1985 Mr. Ward questioned NRR's review practices vis-a-vis competence of users of the LOCA codes. NRR indicated much of their confidence in the licensees code capabilities rests on their track record.

, Initially, NRR will perform audit calculations.

4.. 'W. Tauche (g) discus,ed the development of the NOTRUMP code to meet the TMI II.K.3.30 recuirenent to revise the SB LOCA EM codes. In the wake of the II.K.3.30 requirements, E decided to develop a new l

BE code. Figures 5 i.nd 6 outline the NOTRUMP features. gcompared NOTRUMP calculations to four LOFT and one Semiscale SB LOCA tests.

Results shown indicate good agreement with data, t

!' J.'Guttmann (NRC) detailed the NRC's review of the g NOTRUMP code to meet the II.K.3.30 requirements. NRC had six action items in their review (Figures 7-8). The code was found acceptable for use

- provided the phenomena of core water level depression seen prior

! to loop seal clearing in the Semiscale S-UT-08 tests is adequately modeled in follow-on work. Follow-on tests of this phenomena are planned in Semiscale and ROSA-IV. g will be required to confinn the capability of NOTRUMP to predict the test results if the follow-on tests show significant PCTs during pre-loop seal clearing.; It was noted that both TRAC and RELAP were initially unable t7 calculate this phenomenon. This observation caused some expressWns of concern among the Subcomittee consultants.

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5. The CE presentation on the II.K.3.30 issue was given by J. Holman and G. Menzel. CE's approach to resolution of this issue was to

. justify the adequacy of the existing apprnved SB LOCA EM. The EM was compared with test data and sensitivity studies. Figure 9 .

outlines the technical concerns and resolution effort. Regarding the steam generator model and verification of the Semiscale i phenomenon noted above, CE will do a post-test analysis of the

S-UT-08 Semiscale test.

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ECCS Meeting Minutes April 3, 1985

.NRC's review of the CE SB LOCA model revision effort was detailed by J. Guttmann. Figure 10 lists the NRC action items for its review. NRC found the CE LOCA EM acceptable but, like W, the e

acceptability is conditioned on CE's successful analysis of the Semiscale S-UT-08 test data vis-a-vis the pre-loop-seal-clearing core level depression phenomena.

During discussion of the details of the CE SB EM, the Consultants repeatedly noted that several of the correlations used were quite dated and while they may produce conservative results, the vendor should use more current or physically correct correlations in their models. In response to Mr. Ward, Mr. Guttman indicated that the S-UT-08 phenomena is believed to be typical and was seen at LOFT after very close examination of SB test data.

6. J. Paljug discussed the B&W resolution effort for II.K.3.30. As with CE, B&W decided to justify use of their existing SB LOCA EM.

Figure 11 outlines the II.K.3.30 issues for the B&W EM. B&W noted that the Owners Group commitment to analyses of the MIST integral system test data will be applied to this issue.

NRR's review of the B&W SB LOCA reanalysis effort was discussed by E. Throm. NRR finds the B&W EM acceptable but is requiring confirmatory analysis using the CRAFT-2 EM code against the MIST /0 TIS data. In response to Mr. Ward, Mr. Throm said there are no near-term requirements for CRAFT-2 comparisons against currently available GERDA/0 TIS test data. Mr. Ward was disturbed with this situation. Mr. Lauben (NRR) indicated that the MIST data is most applicable to the Semiscale test (i.e., is the most challenging to .

the code). B&W said the OTIS data will be applied to code development for the MIST test analyses. The B&W Owners Group has )

committeed to some form of verification of the SB EM based on the results of the OTIS/ MIST integral test program (Figure 12).

ECCS Meeting Minutes April 3, 1985 Mr. Ward expressed concern with the overall NRR approach to the II.K.3.30 review. He said he doesn't see any effort to develop a BE approach to SB LOCA modeling vis-a-vis emergency procedure I guideline development. It appears to be a strictly legalistic approach, i.e., models are conservative therefore they-are acceptable. After further dicussion, Mr. Lauben said he would follow-up on this as an action item for future response.

7. The meeting was adjourned at 6:00 p.m.

NOTE: Additional meeting details can be obtained from a transcript of this meeting available in the NRC Public Document Room, 1717 H Street, N.W., Washington, D.C., or one can be purchased from ACE-Federal Reports, 444 North Capitol Street, Washington, DC 20001(202)347-3700.

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CODE FEATURES -

e CONSTANT PRESSURE e NON-EQUILIBRIUM BETWEEN VAPOR AND LIQUID

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o ONE-DIMENSIONAL FLUID FLOW MODEL -

e SPECIAL TREATMENT OF INTERFACES BETWEEN DIFFERENT REGIONS e FLOW REGIME DEPENDENT HEAT TRANSFER MODEL e 2-D R0D QUENCH MODEL

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SYSTEM EFFECTS REFLOOD TESTS FOR ADDITIONAL BASH VERIFICATION Test Range of Parameters Congnents 1

Pressure initial

• Initial Peak (osia) Peak Temo (*F) Power (kw/f t)

FLECHT-SET 60 1100 .84 Reference Test 3105B FLECHT-SET 20 1100 .84 Reference Test 2714B CCT F -Cl -16 60 hot: 1099 .847 Compares to F/S test (Run 25) avg: 962 .667 31058 CCT F -Cl-19 30 hot: 1598 .899 Designated as the (Run 38) avg: 1337 .6308 NRC Evaluation Model Test PWR range of 20-40 hot: 1300-1600 .6 .8 .

parameters avg: 1000-1300 .4 .5

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REVIEd STATUS OF THE BART CODE .

CODES REVIEW STATUS COMPLETED AND APPROVED

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- Hot legs l - Upper plenum j - Cold legs - safety injection -

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TECHNICAL ITEMS AND RESOLilTION EFFORT ITEM RES0LllTION EFFORT o INTEGRAL MODEL VERIFICATION ANALYSIS OF LOFT TEST L3-1 AND L3-6 o MODELPNG 0F ECC INJECTION SENSITIVITY STUDIES OF EFFECT OF THERMAL NON-EQUILIBRIUM o CORE HEAT TRANSFER. COMPARIS0NS WITH THTF DATA o METAL HEAT TRANSFER DESCRIPTION OF EXISTING WALL HEAT TREATMENT IN CEFLASH-4AS o BREAK FLOW MULTIPLIER SENSITIVITY STUDIES OF SUBC00 LED .

AND 2-PHASE DISCHARGE COEFFICIENTS -

o CONDENSATION HEAT TRANSFER DESCRIPTION OF EXISTING METHODOLOGY IN IN SG AND NON CONDENSIBLE GASES CEFLASH-4AS o FLOW REGIME EFFECT ON SENSITIVITY STUDIES WITH PRESSURE DROP IN SG FLOW REGIMES o SG MODELING, PARTICULARLY WITH DESCRIPTION OF SG MODEL IN RESPECT TO SPIKE-LIKE CORE CEFLASH-4AS AND ITS CAPABILITY:

UNC0VERY OBSERVED IN S-UT-8 ANALYSIS OF S-UT-8 IN PROGRESS, e'

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[lI) ECCS MODELING & NON-EQUILIBRIUM EFFECTS

! [Ill}MODELVERIFICATION (IV) FLOW REGlWES (V) CORE HEAT TRANSFER (Yl?METALHEAT

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l NUREG-0737, Section II.K.3.30 Issues a SBLOCA methods evaluation for LOFT S SEMISCALE test data

. o NUREG-0565 Natural Circulation Pressurizer & Surge Line Core level & heat transfer Modeling detail ECC Injection NCGINolv-'""0'k8'E 60'

o Other concerns Two Phase flow effects Leak Discharge Model o ISTd/?t>SD sc7)

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B&WOG MODEL REVIEW

5. Systems Verification / Test Data

! Confirmatory Committments January 3,1985 OG Letter

a. Benchmark CRAFT 2 to OT

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b. Best Estimate CRAFT 2 to verified RELAP5/ MOD 2[

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c. Appendix K CRAFT 2 to verified RELAP5/ MOD 2 t

ACRS kpril 3,1985 E.D.Throm,NRR/DSI/RSB l

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