ML20074A338
| ML20074A338 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 05/03/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20074A336 | List: |
| References | |
| NUDOCS 8305120508 | |
| Download: ML20074A338 (3) | |
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION t'
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o2%y. v f, SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENTS N05. 79 AND 46 TO FACILITY OPERATING LICENSES NOS. DPR-51 AND NPF-6 ARKANSAS POWER & LIGHT COMPANY ARKANSAS NUCLEAR ONE, UNITS 1 AND 2 DOCKET NOS. 50-313 AND 50-368 Introduction By letters dated September 17, 1981 and March 12, 1982, supplemented by letter dated March 16, 1983, Arkansas Power and Light Company (the licensee or AP&L) requested amendments of the Technical, Specifications (TS), Appendix A, appended to Facility Operating Licenses Nos. DPR-51 and NPF-6 for Arkansas Nuclear One, Units Nos. 1 and 2 (AN0-1&2), respectively.
The proposed change would require verification of leak rate testing of the purge supply and exhaust valves prior to reactor startup after every cold shutdown unless the test had'been successfully completed within the previous three months for both ANO-1&2.
Backcround As a result of the numerous reports on unsatisfactory performance of the resilient seats for the isolation valves in containment purge and vent lines (addressed in OIE Circular 77-11, dated September 6, 1977), Generic Issue B-20, " Containment Leakage Due to Seal Deterioration," was established to evaluate the matter and establish an appropriate testing frequency for the isolation valves.
Excessive leakage past the resilient seats of isolation valves in purge / vent lines is typically caused by severe environmental con-ditions and/or wear due to frequent use.
Consequently, the leakage test frequency for these valves should be keyed to the occurrence of severe en-vironmental conditions and the use of the valves, rather than the current requirements of 10 CFR, Appendix J.
It was recommended that the following provision be added to the TS for the leak testing of purge / vent line isolation valves:
" Leakage integrity tests shall be performed on the containment isolation valves with resilient material seals in (a) active purge / vent systems (i.e., those which may be operated during plant operating Modes 1 through 4) at least once every three months and (.b) passive purge systems (i.e., those which must be administratively controlled closed during reactor operating Modes 1 through 4) at least once every six months."
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_ l By way of clarification, the above proposed surveillance specification was predicated on our expectation that a plant would have a need to go to cold shutdown several_ times a year. To cover the possibility that this may not occur, a maximum test interval of 6 months was specified. However, it was not our intent to require a plant to shut down just to conduct the valve leakage integrity tests.
If licensees anticipate long duration power oper-ations with infrequent shutdown, then installation of a leak test connection that is accessible from outside containment may be appropriate. This would permit simultaneous testing of the redundant valves.
. Discussion ANO-1&2 do not have the capability to leak test the purge vent and exhaust valves from outside the containment during power operation.
In order to test these ve.1ves every six months to comply with our position, it would require a shutdown of the plants in order to make entry into the containment. However, it is not the intent of our position to require shutdown only to leak test these valves. Therefore, the licensee, by letter dated March 16, 1983, proposed a TS change which would leak test these valves before startup after each cold shutdown unless the valves were tested within the previous three months. To
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support the licensee's proposed TS change, by letter dated June 7, 1982, the licensee indicated that seal failure was not a problem at AN0-1&2. Past failures of these valves during leak testing were duet in all cases but one, to failure of the valve to seat properly. Also, AN0-1&2 are located in a relatively mild climate which decreases the probability of seal deterioration.
l Also by letter dated March 16, 1983, the licensee provided a review of the operating history for ANO-1&2. This review indicated that each unit has an average operation period of about two months. Therefore, the valves would be tested within six-month intervals under the proposed TS. based on the operating experience that cold shutdown have occurred at least within six months intervals Evaluation We have reviewed the licensee's submittals regarding this' issue and have determined that the proposed TS changes are acceptable based on the following plant unique considerations:
1.
A review of the operating history for both ANO-1&2 shows that each unit has an average operation period of about two months. This will result in a higher frequency of valve testing than our recommendation of every six months.
2.
ANO-1&2 are located in a relatively mild climate, which decreases the probability of seal deterioration.
3.
Seal deterioration has not been a problem at AN0-1&2. Past failures of these valves during leak testing were due, in all cases but one, to failure of the valve to seat properly.
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Environmental Consideration We have determined that the amendments do not authorize a change in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendments involve an action which is insigni.ficant from the standpoint of environmental impact and, pursuant to 10 CFR SSI.5(d)(4), that an environmental impact statement or negative declaration and environ-mental impact appraisal need not be prepared in connection with the issuance of these amendments.
Conclusion We have concluded, based on the considerations discussed above, that:
(1) because the amendments do not involve a significant increase in the probability or consequences of an accident previously evaluated, do not create the possibility of an accident of a type different from any evaluated previously, and do not involve a significant reduction in a margin cf safety, the amendments do not involve a significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (3) such activities will be conducted in compliance with the Commission's regulations and the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Date: May 3, 1983 Principal Contributor:
G. Vissing M. Fields l
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