PNO-V-87-030, on 870410,RHR Sys Capability Lost for Approx 90 Minutes.Caused by Entrainment of Air within RHR Pumps When RCS Water Level Dropped Due to Water Leakage Through Two Valves.Augmented Insp Team Dispatched

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PNO-V-87-030:on 870410,RHR Sys Capability Lost for Approx 90 Minutes.Caused by Entrainment of Air within RHR Pumps When RCS Water Level Dropped Due to Water Leakage Through Two Valves.Augmented Insp Team Dispatched
ML20215G337
Person / Time
Site: Diablo Canyon Pacific Gas & Electric icon.png
Issue date: 04/13/1987
From: Burdoin J, Narbut P
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
IEIN-86-101, PNO-V-87-030, PNO-V-87-30, NUDOCS 8704170038
Download: ML20215G337 (1)


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PRELIMINARY NOTIFICATION OF EVENT Ol? VNySUAL OCCURRENCE--PMO-V-87-30 Date 04/13/87 This preliminary notification condtutet EARLY notice of events of POSSIBLE safety or public interest significance. The inforra den presented is as initially received without verification cr evaluation and is basically all the is known by Region Y staff on this date.

FACILITY: PACIFIC GAS & ELECTRIC COMPANY Emergency Classification D!ABLO CANYON UNIT 2 Notification of Unusual Event DOCKET NO. 50-323 --~~ Alert 5AN LUIS OBISP0 COUNTY. CA Site Area Imergency General Emergency

' TNot Applicable SU8 JECT: AUGMENTED INSPECTION TEAM DISPATCHED TO SITE AS A RESULT OF LOSS OF RESIDUAL HEAT REMOVAL SYSTEM (RHR) CAPABILITY At923pm(PDT).onApril 10. 1987, Aile in Mode 5 with RCS temperature at 90*F and the tater level being maintained at mid-ranga of the reactor vessel hot leg, in preparation for removal of steam generator primary w. ways. Residual Heat Removal System (RNR) capability was lost for a period of approximately 90 minutes. Loss of RHR capability resulted from~

entrainment of air within the RHR pumps when RCS water level dropped unexpectedly due to water leakage through two RCS system valves. During the 90 minute period when RNA capability was lost the RCS temperature increased from 90'F to boiling. The reactor vessel was vented and the contairment equipme,nt hatch was open in preparation for refueling i activities, as allowed by the Technical Specifications. No significant radioactivity releases occurred during this event.

As a result of this incident, and other similar incidents (loss of RHR capability at San Onofre on March 19. 1986, at Zicn-2 on December 10, 1985, at Catawba on April 22, 1985, etc.), an Augmented Inspection Tea'n (AIT) is being dispatched to arrive at Diablo Canyon Unit 2 on the afternoon of April 14, 1987 The primary purpose of the Team is to review the lessons learned from IE Informatica Notice 86-101 and look into such areas as reactor vessel level indication reliability, operator performance, event classification and reporting, and unexpected valve leakage as related to the Diablo Cartyon Unit 2 incident of April 10,1987.

Updates to this PN will be issued as significant findings from the AIT inspection become available.

There has been regional media attention. The*1icensee has issued a press release. Region V has responded to media inquiries.

This information is current as of 6:00 pm (PST) on April 13. 1987.

CONTACT: J. Burdoin RV. P. Narbut .

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