ML20128B444

Safety Evaluation Re Error in Exxon LOCA-ECCS Analysis for Facility.Revised LOCA Analyses Fully Comply W/Requirements of 10CFR50.46 & App K

ML20128B444
Person / Time
Site:	Fort Calhoun
Issue date:	06/13/1985
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20128B416	List: ML20128B411 ML20128B444
References
NUDOCS 8507030229
Download: ML20128B444 (6)

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• g UNITED STATES g[ g NUCLEAR REGULATORY COMMISSION D p WASHINGTON, D. C. 20555

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION OMAHA PUBLIC POWER DI5TRICT DOCKET NO. 50-285 FORT CALHOUN UNIT 1 RESPON5ES REGARDING EXXON CODE ERROR INTRODUCTION On March 15, 1985 Exxon Nuclear Corporation infonned the NRC of a coding error in the T00DEE2 computer code stiich affected the LOCA-ECCS analyses for several PWRs. In refgrence 1 Exxon provided a description of the coding error. The error was in an expression for a multiplier on the reflood heat transfer coefficient. The incorrect coding caused the heat transfer co'fficient e multiplier to be 1.045, when it was intended to be 1.0.

In addition to the coding error in the T000EE2 code, the staff has also become aware of other errors in Exxon LOCA analyses. These include:  ;

-Use of heat transfer augmentation factors for local rod peaking and mixing vanes in some recently submitted LOCA analyses perfonned to support license amendment applications. The use of these factors was found unacceptable some time ago during our review of the EXEM/pWR ECCS evaluation model.

-Discovery of an input error in the St. Lucie Unit 1 LOCA analysis. This error is described in Reference 2.

-Assuming the validity and applicabilty of applying the Wettinghoute-derived K(z)curvetoExxonfuel.

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In order to determine the extent to which the staff concerns with respect to the Exxon LOCA models and analysis methods were generically applicable, the staff contacted all PWR licensees using Exxon fuel on March 20, 1985. At that time, the staff requested that each of the licensees evaluate these concerns with respect to their plants and determine if they were applicable.

On March 25, the licensee for Fort Calhoun Unit 1, Omaha Public Power District, provided in reference 3 their evaluation of the Exxon LOCA issues.

Supplemental information was provided by the licensee in reference 4. The staff's evaluation of this information follows:

2 EVALUATION The current Exxon LOCA analysis, applicable to Cycle 8 operation of Fort Calhoun Unit 1, was transmitted to the staff in reference 5. In reference 3, the licensee stated that they were informed by Exxon that the reference 5 analysis utilized the T00DEE2 code version which had the coding error. The reference 5 analysis did not utilize the unacceptable augmentation factors nor did it contain the St. Lucie Unit 1 input error.

The licensee also provided in reference 3 the results of a revised LOCA analysis using a corrected version of the T00DEE2 code. Via reference 4, the licensee provided supplemental information describing the ECCS evaluation model utilized for the revised analysis. The licensee reported that the corrected evaluation increased the peak cladding temperature from 2052*F to 2104'F.

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3 The staff has reviewed the licensee's revised analysis. Based upon the informa-tion contained in reference 4, the staff has concluded that the evaluation model utilized fully conforms to Appendix K to 10 CFR 50. Also, the staff has have also concluded that the licensee is in conformance with 10 CFR 50.46 as the peak cladding temperature is less than 2200'F.

The remaining Exxon LOCA issue for Fort Calhoun Unit I concerns the validity of assuming use of the Westinghouse-derived K(z) curve for Exxon fuel. Since Fort Calhoun Unit 1 is a Combustion Engineering plant and not a Westinghouse plant, the direct application of this concern is not possible. However, the intent of the K(z) curve is the Westinghouse Technical Specifications is to ensure conformance to 10 CFR 50.46 for a range of power distributions and peaking factors that may occur over the core lifetime per the requirement of Section I.A of Appendix K to 10 CFR 50. Thus, the concern for Fort Calhoun Unit 1 is whether the Exxon LOCA analyses, and the associated plant Technical Specifications, comply with the requirements of Section I.A of Appendix K.

In reference 4, the licensee stated that non-uniform axial power distributions l

were used in the Fort Calhoun Unit 1 LOCA analyses perforned by Exxon. These analyses are discussed in Section 14.15 of the Fort Calhoun Unit 1 FSAR. Based

. upon these analyses an allowable total peaking factor versus core height curve l

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4 was generated. Associated Technical Specifications are employed to-assure this curve is not e.<ceeded. Based upon this information, the staff has concluded that the Fort Calhoun Unit 1 LOCA analyses comply with Section I.A of Appendix K.

CONCLUSION Based upon the foregoing, the staff has concluded that the revised LOCA analyses for Fort Calhoun fully comply with the requirements of 10 CFR 50.46 and Appendix K.

Principal Contributor:

R. Jones, DSI l

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l Reference

1. Letter, G. F. Owsley (ENC) to H. Denton (NRC), " Error in the 48,000 MWD /MTU LOCA-ECCS Analysis for D. C. Cook Unit 1," GF0:85:008, March 21, 1985.

2. Letter, J. W. Williams, Jr. (FPL) to J. R. Miller (NRC), "St. Lucie Unit 1 Docket No. 50-335, ECCS Analysis," L-85-124, March 22, 1985.

3. Letter, R. L. Andrews (Omaha Public Power District) to J. R. Miller (NRC),

" Error in LOCA-ECCS Analysis for Fort Calhoun Station," LIC-85-122, March 25, 1985.

4. Letter, R. L. Andrews (Omaha Public Power District) to J. R. Miller (NRC),

" Error in LOCA-ECCS Analysis for Fort Calhoun Station," LIC-85-141, April 14, 1585. A

5. Letter, W. C. Jones (Omaha Public Power District) to R. A. Clark (NRC).

LIC-82-410, December 29, 1982.

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Mr. R. L. Andrews Omaha Public Power District Ft. Calhoun Station, Unit No. 1 Harry H. Voigt Esq.

LeBoeuf, Lamb, Leiby A MacRae -

1333 New Hampshire Avenue, NW Washington, DC 20036 Mr. Jack Jensen, Chairman Washington County Board of Supervisors Blair, Nebraska 68023 Metropolitan Planning Agency ATTN: Dagnia Prieditis 7000 West Center Road Omaha, Nebraska 68107 Mr. Larry Yandell U.S. NRC Resident Inspector Post Office Box 309 s Fort Calhoun, Nebraska 68023 Mr. Charles B. Brinkman, Manager Washington Nuclear Operations C-E Power Systems 7910 lloodmont Avenue Bethesda, Maryland 70814 Regional Administrator USNRC, Region IV Office of Executive Director for Operations 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011 1

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