PNO-IV-97-050, on 970911,completed Repair of Reactor Caisson Leak by Reducing in-leakage to Less than Ten Gallons/Day. Informed State of CA

PNO-IV-97-050:on 970911,completed Repair of Reactor Caisson Leak by Reducing in-leakage to Less than Ten Gallons/Day. Informed State of CA

ML20216G069
Person / Time
Site:	Humboldt Bay
Issue date:	09/12/1997
From:	Everett V, Spitzberg D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
References
PNO-IV-97-050, PNO-IV-97-50, NUDOCS 9709120201
Download: ML20216G069 (1)

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l 1- September 12,1997 Ef1ELIMINARY NQIlEl0AHQN OF EVENT OR UNULU AL OCCURRENCE PNO-IV 97 05 This preliminary notification constitutes EARLY notice of events of POSSIBLE saf ety or public interest significance. The inf ormation is as initially received without verification or evaluation, and is basically all that is known by Region IV staff in Arlington, Texas on this date.

EnrJJity Licensee Emergency ClassificJt1]pn

. Pacific Gas & Electric Co. Notification of Unusual Ever*

Humboldt Bay 3 Alert San Francisco, California Site Area Emergency General Emergency Dockets: 50133 X Not Applicable

Subject:

REACTOR CAISSON LEAK REPAIRED On September 11,1997 at approximately 4 p.m. (CDT), the licensee informed NRC Region IV that the ef fort to stop a 0,500 gallon / day leak of groundwater into the reactor caisson had been completed and was successful. As a result of the repair efforts, in leakage had been reduced to less than 10 gallonsiday. Humboldt Bay has been shut down since 1976 and in SAFSTOR, Following three earthquakes in April 1992, groundwater in leakage into the reactor colsson began to increase from about 100150 gallons / day to over 9,000 gallons / day in October 1990. The leak then decreased to between 6,000 to 7,000 gallons / day in November 1996, where it has remained relatively constant, in October 1990, the licensee initiated repair efforts. The sepair project involved the injection of a grout material under the floor of the reactor caisson to seal the leak. The reactor caisson, which houses the reactor, is a 60 foot diameter cylindrical concrete and steel structure extending 70 feet underground. The water table is near ground level. Water leaking into the caisson had collected in a floor sump at the lowest level of the caisson and was being pumped into the bay af ter passing through a radiation monitoring system to verify no contamination was present. A radiological waste processing system was available and operational had contamination been detected.

NRR has been informed and the state of California will be informed. The information in preliminary notification has been reviewed with licensee management.

Region IV received notification of this occurrence by telephone from Humboldt Bay at 4 p.m. (CDT) on September 11,1997.

This information has been discussed with the licensee and is current as of 4 p.m. (CDT) on September 11,1997.

Contact:

D. Blair Spitzberg Vincent Everett (817)860-8191 (817)860-8198 9709120201 970911 PDR I&E \ j,)()\

1 PNO-IV-97-050 PDR

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