ML20247E967
| ML20247E967 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 05/08/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20247E962 | List: |
| References | |
| NUDOCS 8905260384 | |
| Download: ML20247E967 (3) | |
Text
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- SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELAT' D TO' AMENDMENT NOS.116 AND 99 TO' E
FACILITY OPERATING LICENSE N05. NPF-4 AND NPF-7 VIRGINIA ELECTRIC AND POWER COMPANY l
i OLD DOMINION ELECTRIC COOPERATIVE j
NORTH ANNA POWER STATION. UNITS NO. I AND NO. 2 DOCKET NOS. 50-338 AND 50-339
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1.0 INTRODUCTION
By letter dated October 19, 1984, Virginia Electric and Power Company (the i
cations (TS) quested changes' to the North Anna, Units 1 and 2 Technical.Specifi-licensee)re I
to add additional surveillance requirements for the butterfly-type containment isolation valves in the containment purge lines and the containment vacuum ejector lines. The licensee proposed to test these valves each time containment integrity is established after containment vacuum has been broken.
The licensee stated that the. proposed TS change is part of the implementation of provisions of NUREG-0737, Item II.E.4.2, " Containment Isolation Dependability" and the guidance developed as part of Multi-Plant Action (MPA) B-24, " Containment Purging During Normal Plant Operation." The following evaluation addresses the
. licensee's TS changes.
2.0 EVALUATION The' licensee proposed to add TS 4.6.1.1.d (surveillance requirements) to the TS for both units to read as follows
" Primary containment integrity shall be demonstrated each time containment integrity is established after vacuum has been broken by pressure testing the butterfly isolation valves in the containment purge lines and the containment vacuum ejector line."
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i The purpose of the leakage integrity tests for these butterfly-type valves is to identify excessive degradation of the resilient seats of ther.e valves. Excessive 4
leakage past the resilient seat of a butterfly valve is typically caused by severe I
environmental conditions and/or wear d'Je to frequent use. Consequently, the leak testing frequency for these valves should be keyed to the occurrence of severe environmental conditions and the use of the valves, rather than to the current containment leak rate testing requirements of 10 CFR Part 50, Appendix J.
These tests are not the Type C tests of valves set out in 10 CFR Part 50, Appendix J.
f These valve leakage tests are to be performed in addition to the Type C tests of the valves required by Appenoix J.
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Each unit of the North Anna plant has seven butterfly containment isolation valves to be leak tested in accordance with the proposed surveillance require-ments of TS 4.6.1.1.d.
They include one 8-inch valve inside containment for the containment vacuum ejector line, two 36-inch valves inside containment and two 36-inch valves outside containment for the containment purge supply and exhaust lines, one 18-inch valve outside containment for containment purge alternate supply units, and one 8-inch valve outside containment for the containment purge bypass line.
Branch Technical Position (BTP) CSB 6-4, Item B.4 specifies that provisions should be made for testing the availability of the isolation function and the leakage rate of these valves during reactor operation, but it does not address test frequency. The criteria of MPA B-24 states that leakage integrity tests be performed for the containment isolation valves with resilient seals in (1) the active purge system (i.e., those which ma operation) at least once every 3 months, and (2) y be operated during reactor the passive purge system (i.e.,
those which must be administratively controlled closed during reactor operation) at least once every 6 months.
Rather than testing the passive purge system valves at 6-month intervals, the licensee proposed to test these valves when containment integrity is re-established after containment vacuum is broken.
The staff notes that the licensee's proposed test frequency deviates from the MPA B-24 recommended test interval.
However, the staff finds the proposed test frequency to be consistent with the intent of MPA B-24 for the following reasons:
(1) The valve leak tests require personnel entry into the containment because some of the test connections are located inside containment.
In addition, a blind flange must be installed on the lines inside containment to permit these valves to be tested individually in the appropriate direction. Therefore, personnel radiological exposure considerations make the leak testing impractical during power operation.
(2)
It is not reasonable to require a plant shutdown every 6 months to satisfy the MPA B-24 test interval guideline.
(3)
Since the leakage integrity tests are conducted following each cycling of the isolation valves, significant additional valve degradation is not expected while the valves are not used.
l (4) The proposed valve leak tests are performed in addition to the required Appendix J Type C test to verify possible valve degradation.
The licensee also proposed changes to the corresponding TS bases to justify the proposed TS changes. The staff concurs with the licensee's proposed TS changes j
and bases since they meet the intent of the staff guidelines for maintaining
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integrity of the containment isolation valves.
t Finally, the licensee also proposed revising the format of the Unit 1 TS to correspond to the Unit 2 TS. The staff agrees with this proposed change and finds it acceptable.
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3.0 CONCLUSION
The staff has reviewed the licensee's proposed changes to TS 4.6.1.1 regarding the frequency of leak testing for the butterfly type isolation valves in the 1
containment purge and vacuum systems.
Based on its review, the staff cone.ludes that the changes meet the intent of the guidelines of MPA B-24 and NUREG-0737, Item II.E.4.2, and therefore are acceptable.
ENVIRONMENTAL CONSIDERATION These amendments involve a change in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and q
changes to surveillance requirements.
The staff has determined that the amend-q ments involve no significant increase in the amounts, and no significant change in the types, of any eft uents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation i
exposu re.
The Comission has previously published a proposed finding that the j
amendments involve no significant hazards consideration and there has been no public comment'on such finding. - Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 651.22(c)(9).
Pursuant to 10 CFR 551.22(b), no environmental impact statement or environmental assess-ment need be prepared in connection with the issuance of the amendments.
CONCLUSION We have concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will i
be conducted in compliance with the Commission's regulations, and the issuance of the amendments will not be inimical to the comon defense and security or to the health and safety of the public.
Date:
May 8, 1989
' Principal Contributor:
J. S. Guo
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