PNO-V-88-021, on 880315,leak of About 100 Gpm Occurred from Downstream Pressure Relief Valve While Opening Upstream Isolation Valve.Approx 650 Gallons of Water Released.No Radioactivity Released.Investigation Underway

PNO-V-88-021:on 880315,leak of About 100 Gpm Occurred from Downstream Pressure Relief Valve While Opening Upstream Isolation Valve.Approx 650 Gallons of Water Released.No Radioactivity Released.Investigation Underway

ML20148C252
Person / Time
Site:	Rancho Seco
Issue date:	03/16/1988
From:	Miller L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-88-021, PNO-V-88-21, NUDOCS 8803220312
Download: ML20148C252 (1)

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PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-V-88-21 Date: 03-16-88 This preliminary notification constitutes EARLY notic! of events of POSSIBLE safety or -

public interest significasse. The information presented is as initially received '

without verification or evaluation and is basically all that is known by Region V staff on this date.

FACILITY: SACRAMENTO MUNICIPAL UTILITY DISTRICT Emergency Classification RANCHO SECO UNIT 1 x Notification of Unusual Event DOCKET N0. 50-312 - - Alert .

HERALD, CA Site Area Emergency General Emergency  :

Not Applicable .

SUBJECT:

COOLANT LEAK IN THE LETDOWN SYSTEM ,

On March 15, 1988 at 2230 PST, with the reactor in Hot Shutdown at normal operating i 1

temperature and pressure, a leak of about 100 gpm occurred from a downstream pressure  !

, relief valve (PSV 22021) while opening the upstream isolation valve to the 'A' Letdown l

, Cooler (SFV 22005) for MOV testing. The leak was within the capacity of the Makeup Pump.

The leak started when SFV 22005 was opened, allowing RCS pressure (about 2200 psi) to be seen' at the Cooler relief valve, PSV 22021. The relief setpoint of PSV 22021 is 2500 psi. In addition to blowdown through the tailpipe discharge to the Reactor Building Sump, the relief valve also blew a bonnet gasket which allowed leakage into the local containment atmosphere. The licensee shut SFV 22005 and isolated the leak at about 2237.

Due to the valve testing in progress, the leak was initially thought to be a packing leak -

from SFV 22005. Inspection subsequent to the event determined the leak was from PSV 22021.

Based on containment sump drainage, it was estimated that about 650 gallons of water was  !

released. An Unusual Event was declared at 2249 and terminated at 2317 PST.

No radioactivity was released as a result of the leak. l The licensee is investigating the cause of the relief valve malfunction, and is in the  ;

process of repairing the valve. The licensee does not expect this to impact the restart i schedule. The Senior Resident Inspector responded to the site upon the initial notification, and the resident inspection staff is continuing to review the event, j This information is current as of 10:00 a.m. PSI. .

CONTACT: L. Miller FTS 463-3700 l

DISTRIBUTION BY 5520: FAX T0: i i

Date d //G Time // , JC Date Time i Chairman Zech EDO RI INP0 Comm. Roberts AE00 RII NSAC Com. Bernthal PA0 RIII LICENSEE r Comm. Carr SLITP RIV RFSIDENT INSPECTOR i Comm. Rogers NRR HQS. OPERATIONS OFFICER SECY NMSS ,

J CA ARM MAIL T0:

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OGC OIA ACRS RES

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1 GPA

RV FORM 211 of; g32g12880316 Revised: 8/19/87 PNO-V-SS-021 DCD h, 3 Y lj

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