ML20086G922
| ML20086G922 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 07/07/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20086G916 | List: |
| References | |
| NUDOCS 9507170287 | |
| Download: ML20086G922 (3) | |
Text
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coces p-Jh UNITED STATES B
NUCLEAR REGULATORY COMMISSION E
f WASHINGTON. D.C. 206eH001
.....f SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO. 89 TO FACILITY OPERATING LICENSE NPF-68 AND AMENDMENT N0. 67 TO FACIllTY OPERATING UCENSE NPF-81 GEORGIA POWER COMPANY. ET AL.
V0GTLE ELECTRIC GENERATING PLANT. UNITS 1 AND 2 DOCKET NOS. 50-424 AND 50-425 1.0 INTRODUCTIOU By letter dated December 27, 1994, Georgia Power Company, et al. (GPC or the licensee) proposed changes to the Vogtle Electric Generating Plant (VEGP),
Units I and 2, Technical Specifications (TSs).
The proposed amendments revise the leakage testing frequency for containment isolation valves installed in the containment purge lines from every 3 months to every refueling outage.
2.0 EVALVATION Primary containments are provided with vent / purge systems to enable the containment to be vented and purged as necessary for control of containment pressure and airborne radiation levels.
Large lines (i.e., 24-inch diameter) are used during outages.
These lines are sealed closed during power operation.
Smaller (i.e., 14-inch diameter) " mini-purge" lines are used on a non-routine basis during power operation.
The containment penetration arrangement is depicted in the figure below. The purpose and use of these lines is discussed in greater detail in Branch Technical Position CSB 6-4 in Standard Review Plan Section 6.2.
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MINJ-PURGE St; TEM TYPICAL PENETRATION ARRRANGEMENT 9507170287 950707 PDR ADOCK 05000424 P
. The 24-inch and 14-inch diameter containment isolation valves installed in the VEGP vent / purge system are butterfly-type valves with seals made of a resilient material.
Because valves of this design have a history of high leakage rates and rapid deterioration, and because the associated leakage path provides significant potential for release of fission products in the event of an accident, the staff imposed accelerated testing requirements (i.e., beyond the minimum Appendix J leak rate requirements) on such valves. The staff 1
position related to surveillance testing of large containment vent / purge valves with resilient seal material is identified in the improved Standard Technical Specifications (STS). The improved STS specify a leakage testing frequency of 184 days and within 92 days of opening the valve. These requirements are intended to apply to all sizes of containment purge valves with resilient seals except for valves installed in lines that are isolated by blind flanges during power operation.
In order to minimize personnel radiation exposure, the staff permits the additional leakage tests that are conducted at power to be performed using methods that do not require containment entry.
The at-power tests may involve a test method that is not identical to the 10 CFR Part 50, Appendix J test procedure.
(The VEGP TS do not reflect this position, but instead indicate that all purge valve leakage tests will be " Type C** [i.e., use the 10 CFR Part 50, Appendix J methodology and criteria for leakage testing of containment isolation valves]).
Operating experience has shown that for well-maintained butterfly valves with resilient seals, used at suitable environmental and operating conditions, the 24-month Appendix J leakage rate test interval is sufficiently frequent.
Accordingly, the staff will approve a reduced leakage testing frequency if supported by plant-specific data (i.e., history of test results).
Generic data is not acceptable for this purpose, since local environmental conditions and frequency of valve operation affects seal performance.
The 24-inch and 14-inch vent / purge valves at the VEGP are currently required by TS to be Appendix J/ Type C leak-tested at 3-month intervals.
Because the Type C test method is specified, the tests involve containment entry and the erection of scaffolding to permit installation of blank flanges to enable the inboard valves to be tested with the pressure applied in the accident direction.
The licensee proposes to reduce the Type C test frequency for containment purge valves to 24 months consistent with 10 CFR Part 50, Appendix J test interval requirements for Type C leakage testing.
The application is based on the results of a total of over 400 Type C tests conducted on the four valves in each of the four penetrations over the period of 1987-1994. No valve exceeded its leakage rate test acceptance criterion of 26,320 standard cubic centimeters per minute on either an initial test or retest.
(On some of the tests, above-average leakage rates were observed and retests conducted.
In these cases, the leakage was found to be due to reasons other than resilient seat leakage).
The VEGP licensee has provided 7 years of historical evidence that the containment vent / purge valves are not subject to accelerated seal deterioration and gross leakage. As 4 confirmatory action, the staff performed a search of its Licensee Event Report database in an attempt to i
1
, identify any vent / purge leakage test failures due to resilient seals. at the VEGP. This search did not reveal any such reports.
Based on this evidence, the valves do not need to continue to be subjected to an accelerated leakage testing frequency. The 24-month test interval prescribed by Appendix J is, therefore, acceptable.
The leakage testing interval for the VEGP vent / purge valves may be extended to 24 months, the maximum interval permitted by 10 CFR 50, Appendix J.
3.0 STATE CONSULTATION
In accordance with the Comission's regulations, the Georgia State official was notified of the proposed issuance of the amendments. The State official had no coments.
4.0 ENVIRONMENTAL CONSIDERATION
The amendments change surveillance requirements. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Comission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (60 FR 6301 dated February 1, 1995). Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
5.0 CONCLUSION
The Commission has 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, (2) such activities will be conducted in compliance with the Comission's regulations, and (3) the issuance of the amendments will not be inimical to the comon defense and security or to the health and safety of the public.
Principal Contributor: William O. Long Date:
July 7, 1995 6
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