PNO-V-91-014, on 910715,licensee Inadvertently Drained 7,000 Gallons of Water from Spent Fuel Pool.Caused by Procedural Weakness.Health Physics Personnel Surveyed Area & Found Min Activity.Util Currently Removing Water from Radwaste Bldg

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PNO-V-91-014:on 910715,licensee Inadvertently Drained 7,000 Gallons of Water from Spent Fuel Pool.Caused by Procedural Weakness.Health Physics Personnel Surveyed Area & Found Min Activity.Util Currently Removing Water from Radwaste Bldg
ML20203C600
Person / Time
Site: San Onofre Southern California Edison icon.png
Issue date: 07/16/1991
From: Andrew Hon, Johnson P
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-91-014, PNO-V-91-14, NUDOCS 9712150364
Download: ML20203C600 (1)


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fy(/ /k n( p UNp (nDLIMINARY NOTIFICATION OF EVENT OR UNUSilAL OCCURRENCE--PNO-V-91-14 Date: July 16, 1991 Y]

This preliminary notification is IARLY notice of events of POSSIBLE safety or public icterest. significance. The infonnation presented is as initially received without verification or evaluation and is basically all that is known by t.he Region V st.aff on this date.

FACILITY: SOUTRERN CALIFORMIA EDISON COHpANY Emeraency Clanalfication San Onofte Unit 3 hotification of Unusual Event Ducket No. 50-362 Alert San Clemente, California Site Area Emergency

_,_,_, Gen 6ral EaHtraency X Not Applicable

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SUDJECT: INADVERTENT DRAININO 07 SPENT FUEL POOL b Q) '

On July 15,1991, at 1:20 p.m. PDT, while the Unit was at full power, the licensen itadvertently drained approximately seven inches (7,000 gallous) of water from the spent fuel pool (SFP). No spent fuel movement was i n p rog re s s a t. t.he t.ime . The control room cperator received an alarm indicating decreasing level in the SFP and immediately cvacuated t.he fuel handling building (FHB). Nu increase in THis radiation level was

(:tected. No plant safety function was affected and no contaminated water was released to the environment.

The cask pool, adjacent to the snain SFP, in normally separat.ed from the main pool by a gate. To provide cooling of the spent fue:1, water is drawn fram the main pool by the SFP p, passed through the SFP heat exchanger, and returned to the main pool and ensk pool rough separate discharge lines. The design of the SFP system is such that this 1 cusp nnot reduce SFP inventory below a safe level.

Before the event, the gate wac open between the main and eask pools, with the discharge volve to the cask pool open, in support of SFP reracking activities which began in Hsvember 1990. In order to support. a maintenance activity in the cask pool, operators closed the gate separating the cask pool tros the main pool. Due to an apparent procedure w:akness, the discharge valve to the cask pool was act closed. This caused some of the returned water to overfill the cask pool, flow to the radweste building susp, overfinwing the atuap to a depth of about two inches on the radwante building floor. This diversion resulted in a level decrease of approximately ten inches in tha main pool. Tbc control trana operator, upon receiving an alarm, recognized tne condition and stopped the SFP pump approximately five minutes after the gate was closed. The water level in the combined SFP aubsequently equaliend at approximately seven Sches below the initial level. Idrensee h:alth physics personnel surveyed the area and found minimal activity.

The licensee is currently removing the water from the radwnste building floor and cvaluating the root cause of thic event. The Resident Inspector responded to affected locatinus la the plant and is following the licenace's actions.

The licensee is preparing a press release. ,p This information is current an of 10:30 a.m. PDT on July 16, 1991. \i

h of CONTACT
A. Hon (7%)a92-2641 P. Johnson (PTS) 448 0300 (O.

o I

9712150364 910716 PDR 18cE PNO-V 014 PDR