05000312/LER-1978-012, Forwards LER 78-012/03L-0

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Forwards LER 78-012/03L-0
ML20147E617
Person / Time
Site: Rancho Seco
Issue date: 10/05/1978
From: Mattimoe J
SACRAMENTO MUNICIPAL UTILITY DISTRICT
To: Engelken R
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
Shared Package
ML20147E621 List:
References
NUDOCS 7810170199
Download: ML20147E617 (2)


LER-2078-012, Forwards LER 78-012/03L-0
Event date:
Report date:
3122078012R00 - NRC Website

text

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i()SMUD SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 S Street, Box 15830, Sacramento, California 95813; (916) 452-3211 October 5, 1978 Nuclear Regulatory Commission (>

A 1, ATTN: Mr. R. H. Engelken NRC Operations Office, g

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Region V 4 Jg/Syg'P Q

1990 North California Boulevard #

Walnut Creek Plaza, Suite 202 #

Walnut Creek, California 94596 hN/ -, \[

Re: Operating License DPR-54 Docket No. 50-312 Reportable Occurrence 78-12 I

Dear Mr. Engelken:

In accordance with Technical Specificat. ions for Rancho Seco Nuclear Generating Station, Section 3.14.4.1, and Regulatory Guide 1.16, Revision 4, Section C.2,b.2, the Sacramento Municipal Utility District is hereby sub-mitting a thirty-day report of Reportable Occurrence 78-12.

l On September 22, 1978, during routine testing of the Cardox (CO2 )

Fire protection System (specifically zone 40 and 41, Diesel Generator Rooms),

! the header f ailed to discharge. In accordance with Technical Specifications j section 3.14.4.2a, a continual fire watch with backup fire suppression equip-ment was initiated. Subsequent investigation revealed that the solenoid that operates pilot valve FY-99809 was not operating. The failure of the pilot valve rendered FV-99809, the main header isolation valve, inoperable for an automatic initiation. At that time, contrary to Technical Specifications i section 3.14.4.1, none of the CO2 z nes,could be considered operable. The

( situation was corrected by disconnecting 'the malfunctioning solenoid and i manually placing the main header isolation valve, FV-99809, in the open l position. This pressurized the header up to all the zone control valves and l made the system operable from automatic zone controls as well as manual pull stations.

Failure of the solenoid was traced to a faulty microswitch which l kept a coil energized, are closed a relay contact and allowed the solenoid to draw up to 20 amps continuously.

All the failed and faulty components were replaced.

Background investigation revealed that prior to the fire protection Technical Specifications, several failures had occurred with this system.

At least one of these previous f ailures was the same mode of f ailure as the latest occurrence. As a result, the District is contacting the vendor in an attempt to obtain a more reliable automatic control mechanism for FV-99809.

Until this is resolved, or some other fix is initiattd which the District feels still preclude a recurrence, the system will be left in the mode previously described (FV-99809 in the open p'o sition and the entire CO2 header g 9

78/0/70/97 0 AN ELLCTRIC S YST E M S E R vlN G MORL THAN 600,000 IN THE HLART Of C A li f 0 R N l A

i R. H. Engelken October 5, 1978 pressurized up to the zone control valves). This mode of operation is conservative and' adequately meets the requirements of Technical Specifications section 3.14.4.1.

The equipment and circuitry involved is supplied by CARD 0X, a Division of Chemetron Corporation.

There was no plant transient or shutdown associated with this event.

Respectfully submitted,

. htt$

J. J. Mattimoe Assistant General Manager and Chief Engineer JJM: RJR:HH:j im Enclosure l cs: Director, MIPC (3)

Director, IE (30) i i

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