ML17291B011

Documents Util Understanding of Conditions Specified in NRC SER for TR WPPSS-FTS-131, Applications TR for BWR Design & Analysis,

ML17291B011
Person / Time
Site:	Columbia
Issue date:	08/28/1995
From:	Parrish J WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
G2-95-169, GO2-95-169, TAC-M81723, NUDOCS 9509070188
Download: ML17291B011 (12)

Text

PRIORITY 1 (ACCELERATED RZDS PROCESSING)

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9509070188 DOC.DATE: 95/08/28 NOTARIZED: NO DOCKET g FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 P AUTH. NAME AUTHOR AFFILIATION PARRISH,J.V. Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Documents util understanding of conditions specified in NRC SER for TR WPPSS-FTS-131, "Applications TR for BWR Design &

Analysis,"

DISTRIBUTION CODE: A001D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: OR Submittal: General Distribution NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD4-2 LA 1 1 PD4-2 PD 1 1 CLIFFORD,J 1 1 INTERNAL: ACRS 6 6 E CEN 1 1 1 NRR/DE/EMCB 1 1 NRR/DRCH/HICB 1 1 NRR/DSSA/S PLB 1 1 NRR/DSSA/SRXB 1 1 NUDOCS-ABSTRACT 1 1 OGC/HDS3 1 0 EXTERNAL: NOAC 1 1 NRC PDR 1 1 D

0 N

NOTE TO ALL "RZDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESKi ROOM OWFN SDB (415-2083) TO ELIMINATE YOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 18 ENCL 17

yl WASHINGTON PUBLIC POWER SUPPLY SYSTEM RO. Box 968 ~ 3000 George Washington Way ~ Richland, Washington 993S2-0968 ~ (509) 372-SOOO August 28, 1995 G02-95-169 Docket No. 50-397 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station Pl-137 Washington, D.C. 20555 Gentlemen:

Subject:

NUCLEARPLANTNO. 2, OPERATING LICENSE NPF-21 CLARIFICATION REGARDING THE SAFETY EVALUATION FOR TOPICAL REPORT WPPSS-FTS-131, "APPLICATIONS TOPICAL REPORT FOR BWR DESIGN AND ANALYSIS" (TAC NO. M81723)

References:

1) Letter dated October 12, 1994, from James Clifford (NRC) to J.V. Parrish (SS), "Approval of Topical Report FTS-131, 'Applications Topical Report for BWR Design and Analysis,'or the Washington Public Power Supply System Nuclear Project No. 2 (TAC No. M81723)"

2) Letter, G02-93-021, dated January 27,1993, from G.C. Sorensen (SS) to NRC, "Nuclear Plant No. 2, Operating License NPF-21, Notification of Request for NRC Review of Topical Report WPPSS-FTS-131, Rev, 1,

'Applications Topical Report for BWR Design and Analysis'"

3) Letter, G02-91-134, dated July 15, 1991, from G.C. Sorensen (SS) to NRC, "Nuclear Plant No. 2, Operating License NPF-21, Response to Request for Additional Information Regarding Topical Report WPPSS FTS-129, 'BWR Transient Analysis Model'" (TAC No. 77048)

Reference 1 provides a Safety Evaluation Report (SER) for the Supply System Topical Report WPPSS-FTS-131 "Applications Topical Report for BWR Design and Analysis," (Reference 2) for use in licensing applications, subject to the conditions specified in the SER.

This letter documents the Supply System's understanding of certain of these conditions and provides a foundation for further clarification. Based on the results of the open meeting held on June 20, 1995, the clarifications provided below may require staff review and approval prior to implementation.

9509070188 950828 P,,

PDR ADOCK 05000397 PDR 1

'.S. Nuclear Regulatory Commission CLARIFICATIONREGARDING THE SAFETY EVALUATIONFOR TOPICAL REPORT WPPSS-FTS-131, "APPLICATIONS TOPICAL REPORT FOR BWR DESIGN AND ANALYSIS" (TAC NO. M81723)

Page Two

~ WATER LEVEL ALC LATIONS SER Statement:

"The algorithm was not qualified for use in any transients in which a large variation (more than 10%) in the mixture level is expected... If any of the transient assumptions, input or models are changed in the future, the licensee must demonstrate to the NRC prior to its use that the model yields conservative results."

The Supply System's interpretation of "large variation (more than 10%) in the mixture level" is "large variation (more than 10% or approximately 56") in the mixture level as measured from the Vessel Zero." In regard to the statement "If any of the transient assumptions, input or models are changed...", the Supply System does not intend to change the transient assumptions or models without prior approval from the NRC. However, the Supply System will make changes in input associated with changes in core composition from cycle to cycle, such as core flow area, hydraulic diameter, spacer loss coefficients and changes associated with plant characteristics. These changes willbe evaluated to ensure the transient assumptions and models are not adversely effected.

~ F EL PELLET-CLADDING GAP C ND TAN E Technical Evaluation Statement:

"The fuel-cladding gap conductance willbe computed by the vendor using an NRC approved methodology".

Supply System Topical Report WPPSS-FTS-131, Section 5.3.3.3, statement:

"Fuel-pellet gap conductance calculated by the vendor's approved methods is used in RETRAN-02 and VIPRE-01".

The RODEX2 code is an NRC-approved code for BWR fuel reload analysis. The code will be used by Supply System engineers to calculate the gap conductances using the same methodology as Siemens Power Corporation (SPC). The Supply System calculated gap conductances have resulted in good agreements in thermal limits as described below.

U.S. Nuclear Regulatory Commission CLARIFICATIONREGARDING THE SAFETY EVALUATIONFOR TOPICAL REPORT.

WPPSS-FTS-131, "APPLICATIONS TOPICAL REPORT FOR BWR DESIGN AND ANALYSIS" (TAC NO. M81723)

Page Three To further confirm the capability of the Supply System reload methodology, additional benchmarking has been performed since the submittal of the Applications Topical Report (Reference

2) and are provided for information. Attachment 1 compares the thermal limits in terms of ACPRs predicted by RETRAN/VIPRE using the Supply System methodology as approved in Reference 1 and those from the fuel vendor SPC for the limiting transients of Load Rejection without Bypass (LRNB) and Feedwater Controller Failure (FWCF). It should be noted that for Cycles 10 and 11, the most limiting transient analyzed by SPC is Turbine Trip without Bypass (1TNB) versus LRNB as predicted by the Reference 1 methodology. The reason that TTNB becomes limiting for SPC analyses is because they revised the turbine control valve operation model from full arc to partial arc to reflect current operating practice. This is an acceptable approach. However, the Supply System has kept the slightly more conservative input of full arc operation. The LRNB and TTNB transients yield about the same b,CPR.

The Cycle 8 results were reported in the Applications Topical Report.

The cases selected for comparison are based on the availability of the SPC data. As seen from Attachment 1, for the limiting fuel type (9x9-9X), the Supply System results are in excellent agreement with the vendor's results for the limiting transient at full power LRNB/TTNB through all four cycles. The differences in the third digit in hCPR between Supply System and vendor results can not be seen in the tables because of rounding-up to two digits by both methods. For the limiting transient at off-rated power levels (FWCF), the, Supply System results are consistently conservative relative to those of the vendor.

It should be pointed out that the Cycle 8 core consists of 564 SPC 8x8 fuel assemblies, 188 SPC 9x9-9X fuel assemblies, and 12 Lead Fuel Assemblies (LFA). The 8x8 assemblies were discharged and 9x9-9X fuel loaded in succeeding cycles. The current cycle (Cycle 11) consists of 136 SPC 8x8 fuel assemblies, 624 SPC 9x9-9X fuel assemblies, and 4 LFAs.

A 5% power uprate was also implemented at the start of Cycle 11. The additional benchmarks confirm the capability of the Supply System's methodology in simulating the changes in core compositions from cycle to cycle and additional changes associated with power uprate, such as increased steam flow, higher dome pressure and higher feedwater temperature.

CI U.S. Nuclear Regulatory Commission CLARIFICATIONREGARDING THE SAFETY EVALUATIONFOR TOPICAL REPORT WPPSS-FTS-131, "APPLICATIONS TOPICAL REPORT FOR BWR DESIGN AND ANALYSIS" (TAC NO. M81723)

Page Four Should you have any questions or desire additional information regarding this matter, please call me or contact Dale Atkinson at (509) 377-4302, incerely,

~ J.V.

Vice Parrish (Mail Drop 1023)

President, Nuclear Operations SHB:sic Attachment CC: LJ Callan - NRC RIV KE Perkins, Jr., - NRC RIV, Walnut Creek Field Office JW Clifford - NRC NS Reynolds - Winston & Strawn DL Williams - BPA (399)

NRC Sr. Inspector - 927N

ATTACHM<2)IT1 COMPARISON OF SUPPLY SYSTEM/VENDOR TRANSIENT ANALYSIS RESULTS IN cLCPR CYCLE 9 Transient %Power/ Scram 8x8 Fuel 9x9-9X Fuel Type %Flow Time+ RPT++ $ $ 440 Spco SS SPC LRNB~ 104/106 TSSS Yes 0.28 0.27 0.26 0.26 FWCF~~ 47/106 TSSS Yes 0.43 0.39 0.44 0.39 FWCF 104/106 TSSS Yes 0.24 0.22 0.22 0.21 Note: SPC data is from SPC Report EMF-93-047 "WNP-2 Cycle 9 Plant Transient Analysis", Siemens Power Corporation, May 1993 Load Rejection Without Bypass Feedwater Controller Failure

+ Technical Specification Scram Speed

++ Recirculation Pump Trip SS - Supply System,

~ SPC - Siemens Power Corporation

C.

'l

COMPARISON OF SUPPLY SYSTEM/VENDOR TRANSIENT ANALYSIS RESULTS IN hCPR CYCLE 10 Transient %Power/ Scram 8x8 Fuel 9x9-9X Fuel Type %Flow Time RPT SS SPC SS SPC LRNB/I%NB~ 104/106 TSSS 0.23 0.25+ 0.22 0.22+

FWCF 47/106 TSSS 0.36 0.34++ 0.38 0.34++

Turbine Trip Without Bypass

+ Data is from SPC Report EMF-94495 "WNP-2 Cycle 10 Plant Transient Analysis", Siemens Power Corporation, June 1994. It is noted that the ACPRs in the report are 0.01 higher than quoted here.

This 0.01 adder is not included here because it is not part of the code calculated hCPR. It was added by SPC to allow for flexibilityin Endwf-Cycle (EOC) axial power distribution achieved during actual operation.

++ Data from SPC "WNP-2 Cycle 10 Design Review 1"

COMPARISON OF SUPPLY SYSTEM/VENDOR TRANSIENT ANALYSIS RESULTS IN hCPR CYCLE 11 Transient, %Power/ Scram 8x8 Fuel 9x9-9X Fuel Type %Flow Time SS SPC SS SPC LRNBfITNB 104/106 TSSS 0.22 0.234'.21 0.214'WCF 45/106 TSSS 0.36 0.32'04'.37 0 31ee Data is from SPC Report EMF-95-006 "WNP-2 Cycle 11 Plant Transient Analysis", Siemens Power Corporation, March 1995. It is noted that the ACPRs in the SPC report are 0.01 higher than quoted here.

This 0.01 adder is not included here because it is not part of the code calculated hCPR. It was added by SPC to allow for flexibilty in EOC axial power distribution achieved during actual operation.

~* Data from SPC "WNP-2 Cycle 11 Design Review No. 1"

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