ML20210A645

Safety Evaluation Supporting Temporary Waiver of Compliance from Tech Specs 1.8 & 3.11 Re Opening of Manual Containment Isolation Valves SI-V-863A - D & SA-V-413

ML20210A645
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	09/11/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20210A602	List: ML20210A596 ML20210A645
References
NUDOCS 8609170294
Download: ML20210A645 (5)

Text

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, #  % UNITED STATES

• 8  % NUCLEAR REGULATORY COMMISSION 5 E WASHINGTON, D. C. 20565

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION CONCERNING A WAIVER OF COMPLIANCE FROM TECHNICAL SPECIFICATIONS 1.8 AND 3.11 CGNNECTICUT YANKEE ATOMIC POWER COMPANY HADDAM NECK PLANT DOCKET N0. 50-213

1.0 INTRODUCTION

By letter dated August 29, 1986, Connecticut Yankee Atomic Power Company (CYAPCO) requested a license amendment to permit the opening of normally closed manual conteinment valves (SI-V-863 A, B, C, and D, and SA-V-413) in order to perform routine maintenance activities and required surveillances. Valves SI-V-863 A, B, C, and D are in the high pressure safety injection system. Periodic surveillance of these valves has been detennined to be important to safety because they can be used to ensure safety injection check valves (SI-CV-862, A, B, C, and D) are passing flow, there is proper boron comentration in the recirculation line, and any precipitated boron is either flushed or redissolved.into solution.

Periodic surveillance of valve SA-V-413 can enhance the operability of the containment continuous leak monitoring system and is also used to maintain the containment pressure within technical specification limits, ff necessary, by injecting outside air to maintain a slightly positive pressure.

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• 4 2.0 EVALUATION In their letter dated August 29, 1986, CYAPC0 has stated that valves SI-V-863 A, 8, C, and D cannot be operated remotely and therefore would j require local manipulation of the subject valves by an operator to perform surveillance tests. Each valve is opened and closed independently so that during the surveillance tests only one valve is open at any time. Further, the licensee has stated that the operators perfonning the valve surveillance tests are in constant communication with the control room. In the event of a containment isolation actuation signal, the operator manipulating the subject valves will be promptly notified and the open valve will be isolated within 60 seconds.

Further, CYAPC0 has stated that if valves SI-V-863 A, B, C, or D should fail to close for any reason, isolation valve SI-V-865 is immediately downstream and in close proximity to the subject valves and can be readily isolated to ensure containment inte'g rity.

CYAPC0 performed a probabilistic risk assessment concerning the unavailability of the subject HPSI valves. Using-statistics on the reliability of check valves, a probabilistic assessment quantitatively confirms that increased surveillance testing would f.T. prove availability f of the HPSI system. A probabilistic risk assessment sensitivity study-was conducted to determine the change in core melt frequency if the ECCS check valves were not tested for a period of three (3) months. The

three (3) month interval was selected as a representative amendment approval interval. The evaluation concluded that the unavailability

of the HPSI system increased approximately 9% assuming a three (3) -

month test interval (compared to a monthly interval) and, the core melt frequency increased approximately 0.4% (over the core melt

frequency assuming monthly testing).

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r The licensee also concluded that the risk associated with opening these manual containment isolation valves for monthly surveillance testing was determined to be negligible in comparison to the risk (contribution to 1 core melt frequency) of not testing of ECCS check valves for a period of three months.

In the August 29, 1986 application, CYAPC0 also requested a license amendment authorizing the opening of Service Air Valve SA-V-413. This would allow periodic testing to verify the operability of containment pressure instrumentation, which is required in determining the operability of the containment continuous air leakage monitoring system. It would also allow charging of the containment atmosphere, if required, to main-

- tain administrative li. nits (again, to ensure the operability of the containment continuous air leakage monitoring system) which are bounded by technical specification limits for containment pressure.

The staff has reviewed the information presented concerning operation of SA-V-413 as requested by the licensee. Valve SA-V-413 requires local manipulation by an operator during the routine maintenance or surveillance activities. The valve is opened and closed independently so that during the surveillance or maintenance operations, only this isolation valve is open at any time. Further, the licensee has stated that the operator performing the valve manipulation is in constant communication with the

control room. In the event of a containment isolation actuation signal, the operator manipulating the subject valve will be promptly notified and the valve can be isolated within 60 seconds. Further discussions with CYAPC0 have indicated that, if valve SA-V-413 should fail to close for any reason, isolation valves SA-V-410 and SA-V-411 are in close proximity

! to the subject valve and can be readily isolated by the local operator within 60 seconds to ensure containment integrity.

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- i Lastly, the licensee also concluded that the. risk associated with opening valve SA-V-413 for limited intervals was extremely small or negligible.

Based upon the information presented above, the staff concludes that the safety benefit associated with operability of the containment continuous air leakage monitoring system far outweighs the potential risk (negligible) of operation of this manual isolation valve.

3.0 CONCLUSION

The staff has reviewed the material provided in the CYAPC0 letter dated August 29, 1986, and concludes that CYAPC0 has demonstrated that the routine monthly surveillance of valves SI-V-83 A, B, C, and D provide a net benefit to plant safety and that the monthly surveillance tests should continue to be condr:ted. The staff also concludes that the safety benefits of reducing the potential core melt frequency and ensuring the operability of the HPSI system far outweighs the risk associated with opening of the subject manual isolation valves under the circumstances described above. Therefore, the staff temporarily waives the compliance with technical specifications 1.8 and 3.11 for valves SI-V-863 A, B, C, and D until the proposed license amer.' ment can be formalized through the nonnal review process.

Similarly, the staff concludes that the safety benefit associated with operability of the containment continuous air le' kage a monitoring system far outweighs the potential risk associated with operation of this manual isolation valve in the interim. Therefore, the staff concludes that a temporary waiver from compliance with Technical Specifications 1.8 and 3.11 for valve SA-V-413 to ensure operability of the containment

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continuous air leakage monitoring system is acceptable until the proposed license amendment can be formalized through the normal review process.

The operation of the subject valve during maintenance-related activities not associated with operation of the stated monitoring system will be reviewed separately as part of our normal review process. We reiterate that these waivers are acceptable given the licensee's commitnent that the operators manipulating the subject valves are in constant communi-cation with the control room and that given a containment isolation signal, these operators are immediately available to isolate the subject valves within 60 seconds.

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