ML20198A280
| ML20198A280 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 12/18/1997 |
| From: | Huffman W NRC (Affiliation Not Assigned) |
| To: | Liparulo N WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 9801050331 | |
| Download: ML20198A280 (5) | |
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- Mr.' Nicholas J. Liparulo, Manager
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' Nuclear Safety an(Regulatory Analysis _ L _
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Nuclear and Advanced Technology Division,
f Westmghouse Electric Corporation" =
P.O. Scx 355 -
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4-Pittsburgh, PA}15230 ;
SUBJECT:
OPEN ITEMS ASSOCIATED WITH THE AP600 SAFETY EVALUATION REPORT
- (SER) ON THE APPLICABILITY OF NOTRUMP FOR ANALYSES OF AP600 SMALL BREAK LOSS-OF-COOLANT ACCIDENTS (SBLOCA)-
c Dear Mr. Liparuloi j The Reactor Systems Branch of the U.S. Nuclear Regulatory Commission has provided an SER Input to the Standardization Project Directorate on the applicability of the NOTRUMP computer -
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. crAe for analyses of SBLOCAs as part of SER Chapter 21. The input has open items as well as
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f application restrictions which have been extracted and designated as Final Safety Evalution (Report open items in the enclosure to this letter.
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.'If you have any questions regarding this matter, you ma'y contact me at (301) 415-1141.
Sincerelyi i
E original signed by:
William C. Huffman, Project Manager.
Standardization Project Directorate -
Division of Reactor Program Management 4
Office of Nuclear Reactor Regulation :
Docket No,52 003 h h -p S y
Enclosure:
As stated ec w/ encl: -See next page :
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DISTRIBUTION
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W IDOCUMENT NAMEFA:NOTRUMP.Ol1 1To receivs a copy.of this document, Indicate in the box:~"C" = Copy without attachment / enclosure ' "E" = Copy _-
i with attachment / enclosure "N" = No copy r
OFFICE' PM:PDST:DRPM-l BC:SRXB:DSSA~' I d D:PDST:DRPM l c : l-NAME WCHuffnian3bl-A TCollins - 4tir TRQuay4W DATE^
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f Mr. Nicholas J. Liparulo Docket No.52-003 -
Westinghouse Electric Corporation AP600 cci ' Mr. B. A. McIntyre Mr. Russ Bell.
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-Advanced Plant Safety & Licensing Senior Project Manager, Programs
. Westinghouse Electric Corporation -
Nuclear Energy institute i
Energy System'; ausiness Unit 1776 l Street, NW 1 P.O. Box 355
. Suite 300 Pittsburgh, PA 15230 Washington, DC 20006-3706-
?.8s. CMdy L.' Haag Ms. Lynn Connor 1
- Advanced Plant Safety & Licensing Doc-Search Associates : -
Westinghouse Electric Corporation
- Post Office Box 34 Energy Systems Business Unit '
Cabin John, MD 20818 Box 355 Pittsburgh, PA 15230 Dr. Craig D. Sawyer, Manager Advanced Reactor Programs Mr. Storting Franks GE Nuclear Energy U.S. Department of Energy 175 Curtner Avenue, MC-754 NE 50, _
San Jose, CA 95125
- 19901 Germantown Road Germantown, MD 20874 Mr. Robert H. Buchholz GE Nuclear Energy Mr. Frank A. Ross 175 Curtner Avenue, MC-781 U.S. Department of Energy, NE-42 San Jose, CA 95125 l
Office of LWR Safety and Technology 19901 Germantown Road' Barton Z. Cowan, Esq.
Germantown, MD 20874 Eckert Seamans Cherin & Mellott 600 Grant Street 42nd Floor Mr. Charles Thompson, Nuclear Engineer Pittsburgh, PA 15219 AP600 Certification NE 50'
- Mr. Ed Rodwell, Manager 3
PWR Design Certification 19901 Germantown Road Germa 1 town, MD 20874 Electric Power Research Institute 3412 Hillview Avenue Palo Alto, CA 94303.
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SER OPEN ITEMS AND RESTRICTIONS ASSOCIATED WITH THE APPLICABILITY OF NOTRUMP FOR ANALYSES OF AP600 SMALL BREAK LOSS-OF-COOLANT ACCIDENTS,
- FSER SECTION 21 -
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. 440.749F -
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. Westinghouse has not yet provided sufficient evidence to the staff to demonstrate that the use of L
the Henry /Fauske and HEM models for the calculation of the discharge rate from the ADS is conservative.
440.750F -
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. Several logic additions have been made to the NOTRUMP code, including the Fluid Node Stacking, Mixture Level Overshoot, and Bubble Rise logic. The proper functioning of these logic schemes.
L while interacting can be demonstrated best in the analysis of the SPES and OSU integral system tests. These tests have been analyzed and documented in the NOTRUMP Final Verification and
- Validation Report. The results yield reasonable agreement between the experimental data and the
- NOTRUMP calculation'except for the double-ended guillotine break of the direct vessel injection
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(DVI) line transients in SPES and OSU. In the double-ended guillotine break of the DVI line, the L
core level is over predicted and the Westinghouse explanation does not identify the root cause of L
the problem within NOTRUMP.' The root cause needs to be explained by Westinghouse and a.
lt strategy nsads to be developed to reliably use the code for analysis of double-ended guillotine E
breaks of a DVI line in the AP600 design.
. 440.751F -
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The staff has not yet completed its review of the Westinghouse response to RAI 440.721 due to its late submittal. The acceptability of the response is an open item.
440.752F L
' The following application restrictions on using NOTRUMP for AP600 analyses should be clearly l
documented in both WCAP 14807, "NOTRUMP Final Verification and Validation Report," and the AP600 SSAR.
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- The NRC staff makes no judgment at this time regarding the changes in the numerical solution techniques in the NOTRUMP heat links when transition boiling is predicted to occur.
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Should NOTRUMP be applied to calculations for which there is indication that this methodol-L
-ogy is being invoked, the staff should be informed and requested to review !.he modified transition boiling correlation solution scheme.
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The staff notes that NOTRUMP can not calculate the effects of non-condensible gases injected into the primary coolant system during the AP600 SBLOCA. The presence of non-condensible gases is a concem due to the possible degradation in performance of the PRHR HX. However, the non-condensible gases generally enter the PRHR late in tFe transient,~ -
1-when the PRHR HX is no longer playing a significant role in heat removal. Thus, the non-condensible gases do not appear to have a significant effect on the course of the event. The staff accepts the NOTRUMP code for evaluation of the AP600 SBLOCA in spite of this shortcoming. However, if scenarios are found which cause non-condensible gases to reach th DRHR HX while it is actively removing heat from the primary system, the staff should be p
informeM requested to re evaluate this deficiency.
' 3.
The staff is aware that Westinghouse has submitted modifications to the NOTRUMP code incorporating a condensation model based on results of the COSI SI/ steam condensation experiments. The pressure range covered by the COSI tests is outside of the range of interest for the low pressure conditions expected in the AP600 SBLOCA. In addition, the i
AP600 design uses direct vesselinjection of the St. Westinghouse has not referenced use of the COSI condensation modelin any of the documentation, or RAI responses, pertaining to -
the NOTRUMP applicability to AP600, Westinghouse has stated that the COSI condensation
- model will not be used in the AP600 NOTRUMP code. The position of the staff is that the COSI condensation modelis neither applicable nor acceptable for evaluation of the AP600 l
4 440.795F-Westinghouse stated during the December 10,1997, ACRS Thermal / Hydraulic Subcommittee meeting that changes had been made to the NOTRUMP code numerics. The code numerics must be described in full detail, including derivation of all difference forms of the equations being solved.
In addition, every equation altered or changed from the form that exists in the original, apWved NOTRUMP code must be provided with derivation complete to the level of the difference form in the i
code.
I 440.796F The following commitments were made by Westinghouse at the conclusion of the December 10, 1997 ACRS T/H Subcommittee meeting and must be fu! filled.
. a. Momentum Flux - deficiencies are to be benchmarked against additional detailed calcula-tions using actual two-phase flow equations that include the effects of compressibility, including the condition of constant entropy.
- b. ADS 1 the test data analysis report is to be reviewed to assure that the data reduction was performed correctly,
- c. Entrainment - consider as part of the overall scaling and level penalty development.
. d. Level Penalty-a multiloop scaling analysis is to be performed for the time period of ADS 4 and IRWST draining. Justify the basis for ADS flow, ADS 4 flow affected by entrainment
- of liquid and the corresponding effect on the pressure loss due to two-phase flow. This is to be described in sufficient detail that a step towards scaling to AP600 can be made.
- e. Surge Line Flooding - an effort similar to that applied to the level penalty is to be made.-
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- f. Noding - provide more justification for the Dasis used which differs from the accepted approach developed under the CSAU work, especially for the PRHR and downcomer.
440.797F The "AP600 Scaling and PIRT Closure Report," WCAP 14727 is to be redone to support resolution of the issues identified in 440.795F and 440.796F above.
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