PNO-V-86-012, on 860327,loss of Both Shutdown Cooling Trains Experienced Due to Loss of Pump Suction & Cavitation.Caused by Reactor Vessel Water Vortexing Causing Air to Be Pulled Into Shutdown Cooling Lines

PNO-V-86-012:on 860327,loss of Both Shutdown Cooling Trains Experienced Due to Loss of Pump Suction & Cavitation.Caused by Reactor Vessel Water Vortexing Causing Air to Be Pulled Into Shutdown Cooling Lines

ML20140J542
Person / Time
Site:	San Onofre
Issue date:	03/28/1986
From:	Chaffee A, Narbut P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-86-012, PNO-V-86-12, NUDOCS 8604040354
Download: ML20140J542 (1)

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PRELIMINARY NOTIFICATION EVENT OR:UNOSUAL OCCURREN'CE-PNO-V-86-12 Dates.03/28/86

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Thia preliminary notification constitutes EARLY notic',of events off OSSIBLE safet'y or public i e P Tintsrsst significance. The information' presented is as initially received without. verification lcr

cysluation and is basically-all that is_known by Regio'n V staff on this:date.

, ,. ,,2 i 4.; FACILITY: Southern California Edison Company Licensee Emergency Classification San Onofre Unit s . . Notification of Unusual Event.

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DOCKET NO.'50-361 -

Alert Site. Area Emergency "

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General Emergency XX Not Applicable-

SUBJECT:

LOSS'0F SHUTDOWN' COOLING I

Tha unit has been shu'tdown for a refueling outage'since'3/15/86. -On the. evening of23/26/86.

'chutdown cooling was'in operation with the unit in Mode 5 with the Reactor Vessel head installed

.' At 00:50 EST 3/27/86, the l;cndeithwaterlevelat82inchesbelowtheReactorVesselflange.

unit had a loss of both trains of shutdown cooling because of loss of pump suction and pump a cavitation.:.This was apparently caused by reactor vessel water vortexing causing air.to be pulled into the shutdown cooling lines'. The LPSI pump No. 16 was manually stopped. -Pump starts?

cf LPSI pump Nos. 15 & 16 were made but did not resolve the' air binding. The line was then uvantid and the reactor vessel water level was raised .2 inches. The No. 16 LPSI pump' was regterted and

is operating without further problems. The entire event was less than I hour in-

duration. The bulk RCS temperature rose from 115'F to 180'F_during the event, as' reported to

tha hsadquarters' duty officer by licensee staff. The resident inspectors have been examining tha cvent including review of data and interviews of personnel. At this time unresolved quistions exist which will be pursued. It appears that a possibility exists that saturation temparatures may have been reached in local areas of the core based on a Th reading of 210'F

- during the period no ' flow was in progress.

Th2 licensee has~ determined that erroneous level readings were caused by a kink in the tygon tubs level indicator.- The kink.has been repaired. The licensee has implemented additional cdministrative controls,' including operator walkdown of the level indication system,:to prevent

-r:currence.

Lic3nzee management is pursuing.further definition of bulk temperatures achieved and has-dstsreined that no fuel damage cccurred due to the low heat flux values.

'Th2 licensee plans to continue with refueling operations at this time.

Th N.information is current as of 11:00 am PST March 28, 1986.

hCONTACT: . A. Chaffee , P. Narbut

. s FTS 463-3753 'FTS 463-3730 I DISTRIBUTION 4 H St.- MNBB Phillips E/W Willste Air Rights Mail:

Chairman Palladino EDO NRR IE NMSS ADM:DMB Comm.iZech - PA OIA RES DOT:Trans Only Comm. Bernthal MPA AEOD Comm,' Roberts ' ELD s Comm.'Asselst'ne Regions:

SECY 'INP@.% NSAC2/ WA

'ACRS Licensee: J2.' y>/

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CA . (Reactor Licensees) REGION V: FORM 211 PDR Resident Inspector _ (Revised 3/14/83) 8604040354 860328 _

PDR I8E PNO-V-86-012 PDR Q (

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