ML19290B740

RO-79-055-01P:Westinghouse Notified Util of Potential for P-4 Permissive Failures to Remain Unidentified During Performance of Surveillance Tests.Details Will Be Provided in Followup Rept

ML19290B740
Person / Time
Site:	Farley
Issue date:	11/08/1979
From:	Hairston W ALABAMA POWER CO.
To:
References
FNP-79-1354, NUDOCS 7912130621
Download: ML19290B740 (2)

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n Alabama Power P. O. Drawer 470 Ashford, AL 36312 November 8, 1979 FNP-79-1354 Mr. J. P. O'Reilly, Director U. S. Nuclear Regulatory commission 101 Marietta Street, N.W.

Atlanta, Georgia 30303

Dear Mr. O'Reilly:

This is to confirm the telephone call to Mr. William Bradford at 1243 on November 8, 1979 by Mr. W. G. Hairston.

Westinghouse Electric Corporation notified Alabama Power Company that the potential exists for certain P-4 permissive failures not being identified during the performance of surveillance tests.

The P-4 permissive is used as an input to the Engineered Safety Features Actuation System (ESFAS) to indicate the status (open or closed) of the Reactor Trip breakers. The P-4 permissive provides an interlock in the ESFAS to enable or defeat the capability to manually reset and block Safety Injection (SI).

In operation the initiation of SI instantly trips the reactor and simultaneously starts an electric timer. Af ter a preset time interval, the timer effectively returns system control to the operators for manual reset and block of SI in order to either begin ECCS switchover from the injection phase to the recirculation phase or terminate SI. The system permits manual reset and block of SI only if the P-4 permissive indicates that the trip breakers are open (i.e. , the reactor is tripped).

During normal plant power operation, the P-4 permissive prevents manual actions which could electrically block SI.

The failure modes of the P-4 contacts are (1) contacts fail to close when the reactor trip breakers open, or (2) contacts fail to open when the breakers are closed. Failure mode (1) could prevent the normal mode of resetting and blocking SI.

The consequences of failure mode (2) are such that following a previous initiatien of SI and manual reset and block, the block of SI would remain AgJ following the reset of the reactor trip breakers. $

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Alabama Power Company has not fully evaluated this information; however, it is felt that this is a potential item of reportability under Technical Specification 6.9.1.8.i. Further details will be provided in the followup report.

Sincerely, vd . .M,MW W. G. Hairston, III Plant Manager Joseph M. Farley Nuclear Plant WGH/HMM:kw1 cc: Mr. H. O. Thrash Mr. R. D. Hill File 1555 068