ML19276F636

LER 79-026/03L-0 on 790306:RHR Discharge Valve Opened Accidentally Causing Loop C Accumulator Level to Drop Below Min Volume Required.Caused by Accidental Operation of MOV-1720B.Valve Closed & Loop Accumulator Level Restored

ML19276F636
Person / Time
Site:	North Anna
Issue date:	04/03/1979
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19276F577	List: ML19276F576 ML19276F636
References
LER-79-026-03L, LER-79-26-3L, NUDOCS 7904060283
Download: ML19276F636 (2)

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b 00 63 OO KETrM.%EH EVENT DESCRIPTION AND PROB AHLE CONSEQUENCES O 2 l 0n 3/6/79 at approximately 0031, an RHR Discharge valve opened accidentally causinq l g 3  ; the loop C accumulator level to drop below the minimum volume of 7580 gal. required l g , ;by Tech. Spec. 3.5.1. During this occurrence, the loop A and 8 Accumulators remained I g s; ,available. Therefore, the health and safety of the 9eneral public were not affected. l O a lThis event is reoortable under Tech. Spec. 6.9.1.9.b. I l o 171 I I O H l l

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33 34 36 3/ 40 41 43 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i o IThe cause was accidental operation Of MOV-1720R- Thn ir,T'ndiato enernctivo actinne

, i lwere to close the valve and restore the 1000 C accumulator level within One hour as I i 7 l permitted by Action Statement T.S. 3.5.1.a.

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NAME OF PREPAREH

• 0 PHONE: 703-894-5151

Virginia Electric and Power Company

Attachment:

Page 1 of 1 North Anna Power Station, Unit #1 Docket No. 50-338 Report No. LER 79-026/03L-0 Description of Event On 3/6/79 at approximately 0031, an RHR Discharge Valve (MOV-1720B) was accidently opened when a control room chart recorder door with a loose -inge fell open striking the valve open pushbt.tton. This caused an abnormal system lineup connecting the " loop C" Safety Injection Accumulator to the pressurizer relief tank via the RHR pump suction relief valves RV-1721 A & B. The " loop C" accumulator level then dropped below the 52.9% Tech Spec. minimum level.

Probable Consequences of Event:

The estimated water loss from the " loop C" accumulator during this event was 400 gal. This is based on the amount of water required to refill the accumulator. This amounts to about 5.3% of the minimum required volume of 7580 gal. During this event the loop A & B accumulators were both unaffected and remained available if required to mitigate the consequences of an accident.

'iherefore the health and safety of the general public was preserved.

Cause Loose screws on a control room chart recorder door caused the door to fall and strike the "open" pushbotton of MOV-1720B when the operator attempted to open the chart recorder door.

Immediate Corrective Action The immediate corrective action was to close MOV-1720B and restore accumu-lator level to within the operating band required by Tech. Spec. 3.5.1. The chart recorder door screws were replaced and tightened as necessary.

Scheduled Corrective Action No further action required.

Action Taken To Prevent Recurrence A deflecting device will be installed to protect the controls for MOV-1720A and MOV-1720'