PNO-V-87-041, on 870602,engineer in Containment Noted Weepage from RHR Sys Line While RHR in Svc.Cause of Effect Undetermined.Licensee Preparing Work Orders to Isolate, Examine & Repair Weld

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PNO-V-87-041:on 870602,engineer in Containment Noted Weepage from RHR Sys Line While RHR in Svc.Cause of Effect Undetermined.Licensee Preparing Work Orders to Isolate, Examine & Repair Weld
ML20214W476
Person / Time
Site: Diablo Canyon Pacific Gas & Electric icon.png
Issue date: 06/03/1987
From: Mendonca M, Narbut P
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:
References
PNO-V-87-041, PNO-V-87-41, NUDOCS 8706160039
Download: ML20214W476 (1)


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PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PNO-V-87-41 Date 06/03/87

.This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. 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: PACIFIC GAS & ELECTRIC COMPANY Emergency Classification DIABLO CANYON UNIT 2 Notification of Unusual Event DOCKET NO. 50-323 Alert SAN LUIS OBISP0 COUNTY, CA Site Area Emergency General Emergency XX Not Applicable

SUBJECT:

RESIDUAL HEAT REMOVAL SYSTEM VENT LINE WELD CRACK On June 2,1987 at 11:00 pm (PDT) an engineer in containment noted weepage from a residual heat removal (RHR) system line while RHR was in service. The unit is in its first refueling outage, and drain down of the refueling cavity in preparation for head reinstallation was in progress. The licensee stopped drain down with the water level approximately five feet above the reactor vessel flange The licensee made a four hour reportable event to the NRC. This notification was based on the fact that the RHR system may have not been able to fulfill its safety function. The licensee is analyzing the affect on the system of the potential break. Leakage from the vent line would slightly reduce RHR injection flow in the event the system were needed for a large break LOCA. However, the vent line is potentially isolable and the use of the RHR hot leg recirculation piping (about 19.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> after the initial break to preclude boric acid precipitation) is optional in the licensee's procedure.

The weepage noted was from a weld on a 3/4" vent line on the hot leg recirculation RHR piping in containment (high point vent 2-932 just prior to valve 8703). The weepage is located at a sockolet fitting in the hot leg recirculation piping where the 3/4" vent piping is attached. The configuration is understood to be similar to a socket weld.

The licensee is preparing work orders to isolate, examine, and repair the weld. The licensee intends to determine the cause of the defect. The licensee also intends to continue drain down and reinstall the reactor vessel head to reduce a growing airborne contamination problem and to reduce local radiation levels due to " shine" from the cavity.

The licensee public affairs personnel do not intend to issue a press release today, but will include a statement in tomorrow's normal plant status press release.

No media interest has been expressed. .

This information is c rent as of 12 noon (PDT) June 3, 1987.

CONTACT: M. Mendonca, RV P. Narbut FTS 463-3720 805-595-2354 ~

8706160039 870603 DISTRIBUTION $ _yl 8 -041 PDR H St. MNBB Phillips E/W Willste ~

Air Rights Mail:

Chairman Zech ED0 NRR IE NHSS ADM:DMB Comm. Roberts PA OIA RES D0T:Trans Only Comm. Asselstine MPA AE0D Comm. Bernthal OGC Comm. Carr Regions:

SECY INP0/: 20 NSAC /: 2S ACRS Licensee: #177 CA (Reactor Licensees) REGION V: FORM 211' PDR Resident Inspector fl# (Revised 3/14/83) .

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