ML20210K488
| ML20210K488 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 08/03/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20210K484 | List: |
| References | |
| NUDOCS 9908060141 | |
| Download: ML20210K488 (2) | |
Text
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UNITED STATES g
j NUCLEAR REGULATORY COMMISSION o
WASHINGTON, D.C. 2066H001 s...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS.113 AND 101 TO FACILITY OPERATING LICENSE NOS. NPF-76 AND NPF-80 STP NUCLEAR OPERATING COMPANY DOCKET NOS. 50-498 AND 50-499 SOUTH TEXAS PROJECT. UNITS 1 AND 2
1.0 INTRODUCTION
By application dated March 2,1999, as supplemented by letter dated July 13,1999, STP Nuclear Operating Company, et al., requested changes to the Technical Specifications (TSs) for the South Texas Project, Units 1 and 2. The proposed changes would allow the use of a
" check valve with flow through the valve secured" as an additional means to isolate an affected containment penetration (i.e., a penetration with an inoperable barrier) in TS 3.6.3, Action b, and the associated Bases section.
The July 13,1999, supplement provided additional clarifying information within the scope of the original Federal Reaister notice and did not change the staff's initial proposed no significant hazards consideration determination.
2.0 BACKGROUNQ The South Texas Project containment isolation system design includes several inside containment isolation valves, which are check valves. This design is consistent with and satisfies the requirements of Title 10 of the Code of Federal Reaulations, Part 50, Appendix A, General Design Criteria 55 and 56.
3.0 EVALUATION The containment isolation valves form part of the containment pressure boundary and provide a means for fluid penetrations to be provided with two isolation barriers. Often, a penetration has two containment isolation valves that may be open, but which close automatically if there is an accident. If a containment isolation valve becomes inoperable, degrading the redundancy of containment isolation for that penetration, the current TSs allow plant operation to continue if the penetration is closed and positively isolated within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. This is done with a closed and deactivated automatic valve, a closed manual valve, or a blind flange.
The licensee proposes to add one more item to this list of allowed means for isolating a penetration with one inoperable containment isolation valve, this being a check valve with flow through the valve secured. A simple check valve, by its very nature, cannot be directly secured in the closed position. There is no hand wheel to turn or lock; no operator to control or deactivate. However, the staff has found that,if flow through a check valve has been secured i
9908060141 990803 PDR ADOCK 05000498 P
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. (for example, by closing another valve somewhere in the line), then it can effectively close the line, since the staff can assume it will remain in its closed position when there is no flow.
However, this assurance is not so great as that provided by a closed and deactivated automatic valve, closed manual valve, or blind flange. Therefore, the staff only allows the check valve to be used in this way in a line that still has one operable containment isolation valve, which provides redundant isolation capability. That is why the licensee has included, in its proposed TSs, a note that states: "A check valve may not be used to isolate an affected penetration flow path in which more than one isolation valve is inoperable or in which the isolation barrier is a closed system with a single isolation valve (i.e., General Design Criteria 57 penetration)"
' (July 13,1999, letter).
Based on the ab' ve, the proposed change to allow the use of a " check valve with flow through o
the valve secured" as an additional means to isolate an affected containment penetration (i.e., a l
penetration with an inoperable barrier), with certain restrictions, in TS 3.6.3, Action b, and the associated Bases section, is acceptable. The staff also notes that the proposed change, as supplemented, is consistent with NUREG-1431, " Standard Technical Specifications, l
Westinghouse Plants."
4.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Texas State official was notified of the j
proposed issuance of the amendments. The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
i The amendments change a requirement with respect to installation or use of a facility component located within the restricted area a defined in 10 CFR Part 20. The NRC staff has i
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 Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration, and there has been no public comment on such finding (64 FR 17030). 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.
6.0 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 J
operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor: J. Pulsipher Date:
August 3, 1999
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