ML20148N235

Safety Eval Rept of Main Stream Isolation Valve Test Results. Util Request for Continuing CNS in Present Fuel Cycle for Addl mid-cycle Msltv Leak Test Is Approved

ML20148N235
Person / Time
Site:	Cooper
Issue date:	11/01/1978
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20148N233	List: ML20148N228 ML20148N235
References
TAC-06754, TAC-6754, NUDOCS 7811270043
Download: ML20148N235 (2)

Text

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, SAFETY EVALUATION REPORT OF MAIN STEAM

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O ISOLATION VALVE TEST RESULTS COOPER NUCLEAR STATION DOCKET N0.: 50-298 1.0 Introduction The Cooper Nuclear Station (CNS) Technidal Specifications

! establish a leak rate of 11.5 SCFH/hr at 29 psig as the limiting

, condition for each of the main steam line isolation valves (MSLIV's)atCNS. To assure that the MSLIV leakage will be

controlled within the acceptable limits, in Supplement No. 1, to the CNS SER, dated July 16, 1973, and by letter dated July 27, 1973, the staff approved an augumented program i for the measurement of MSLIV leak rates. This program required an additional mid-cycle leak rate measurement during the first operating fue.1 cycle. The objective of the program was to obtain sufficic-t leak rate data to determine whether a positive sealing system should be installed on the MSLIV at CNS. The licensee, Nebraska Public Power District (NPPD),

has committed to install a positive sealing system if the results of the program indicate that the technical specifi-l cation limit could not be maintained.

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8 The MSLIV's were tested in September,1975, September,1976, and April 1977. The results of the three tests were reported a

by NPPD's letters dated October 30, 1975 and June 2, 1977.

Our evaluation of the test results was contained in the Safety Evaluation Report dated July 14, 1977. Our evaluation indicated that the three MSLIV leak test data were inconsis-

. tent because two of the three tests were in excess of the l specification limits. We, therefore, concluded that additional l test data should be obtained by extending the augumented

test program to the next Type A leak test.

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! By letter, dated September 11, 1978, NPPD reported two additional l MSLIV leak test results of routine Type C testing. Our evaluation of the information presented by the licensee follows.

.6 2.0 Evah.a ti on ,

,. Since the July 14, 1977 Safety Evaluation Report, CNS has conducted two additional MSLIV leakage tests (one in September, 1977 and the other in April,1978). The tests were routine Type C tests and were conducted in accordance with the same

, testing procedure as described in NPPD's letter dated October 30, 1975. The results of both tests are 33.6 SCFH and 28.0 SCFH, and are within the technical specification limit of 46.0 SCFH.

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- 2-The results of the last two tests along with the previous tests provide us consistent and sufficient data base to conclude (1) that the internal seating surface of the MSLIV's has been functioning satisfactorily over the past two-year period, and (2) that the four consistent MSLIV leak tests over a two-year period has met the origii.al intent of the augmented test program.

3.0 Conclusion -

Based on the above disucssions, we find that NPPD's request is acceptable for not shutting down CNS inthe present fuel cycle for the specific purpose of conducting one additional mid-cycle MSLIV leak test.

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