05000312/LER-1982-001, Forwards LER 82-001/01T-0.Detailed Event Analysis Submitted

Forwards LER 82-001/01T-0.Detailed Event Analysis Submitted

ML20042A854
Person / Time
Site:	Rancho Seco
Issue date:	02/09/1982
From:	Mattimoe J SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20042A855	List: 05000312/LER-1982-001, Forwards LER 82-001/01T-0.Detailed Event Analysis Submitted 05000312/LER-1982-001-01, /01T-0:on 820130,both Doors on Airlock Opened Simultaneously Resulting in Loss of Containment Integrity. Caused by Personnel Error & Failure of Inner Door Mechanism to Latch Properly
References
NUDOCS 8203240209
Download: ML20042A854 (2)

LER-1982-001, Forwards LER 82-001/01T-0.Detailed Event Analysis Submitted

Event date:
Report date:
3121982001R00 - NRC Website

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O SMUD SAC 9AMENTO MUNICIPAL UTILITY DISTRICT O 6201 s street, som 15 Califorrua 95813; (916) 452 3211 (9

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February 9, 1982 3

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DOCKET N0. 50-312 LICENSE N0. DPR-54 FOLLOW-UP TO REPORTABLE OCCURRENCE N0. 82-01 In accordance with Rancho Seco Nuclear Generating Station Technical Specification Section 6.9.4.1(i) and Regulatory Guide 1.16, Section C.2.a(9), the Sacramento Municipal Utility District hereby submits the following 14-day follow-up report of Licensee Event Report 82-01.

On January 30, 1982, maintenance personnel attempted to make a con-tainment entry for snubber inspection via the personnel hatch.

Initially both doors were closed. The individual attempted to open the inner door first, however recognized his error and reclosed the inner door. Then he began to open the outer door,as he properly should, to gain entry.

The door interlocks permitted the outer door to open although the inner door had not actually latched. Apparently, the inner door had closed then had rebounded from its seat a sufficient distance that the latching mechanism, although closed, did not engage. The closed mechanism pro-vided the mechanical interlock to pennit the outer door to open, even though the door itself was not latched closed. As soon as the outer door latching mechanism had cleared, the door swung open. This was due i

to the fact that the containment was at a pressure of approximately 5" water below the auxiliary building. This pressure difference was due to the purge that was then in progress.

At this mint, the outer door was fully open and the inner door had been forced open a few inches by the pressure surge.

Plant personnel imediately closed the outer door and latched it, then the inner door was closed and latched. Estimated time for the closing of the doors was two to three minutes.

The air lock doors appeared to close satisfactorily and the only damage was a pinion shaft that operates an equalizing valve in the air lock. f8})

This was repaired by the end of the day on February 1,1982.

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R H EflGELKEfi February 9, 1982 be noted that this valve does not have to operate for the air lock to be functional. The air lock doors were leak tested using the standard local leak rate procedure, SP 205.02, and were found to be acceptable.

The Plant Review Conmittee reviewed this event on February 2,1982 and recommended investigation of specific methods to avoid door misoperation.

A follow-up to this LER will be issued upon determination of what engineer-ing renedies, if any, are desirable.

The District feels that this event points out a potential generic problem, since the air lock at Rancho Seco was manufactured by Chicago Bridge and Iron and many other facilities use air locks of similar design manufactured by CB&l.

Since the plant was in hot standby and the doors were closed almost immedi-ately (within two to three minutes), there were no transients as a result of this event, nor was plant or public safety affected.

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/ John J. Mattimoe Assistant General flanager and Chief Engineer cc: I&E Wasnington (30)

MIPC (3)

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