ML13330A076

Requests Addl Info Re Failure of Saltwater Cooling Sys on 800310.Info About Events Where Multiple Equipment Failures Occur & Contributing Factors Would Be Beneficial

ML13330A076
Person / Time
Site:	San Onofre
Issue date:	06/20/1980
From:	Lainas G Office of Nuclear Reactor Regulation
To:	Dietch R SOUTHERN CALIFORNIA EDISON CO.
References
TAC-65149, NUDOCS 8007210591
Download: ML13330A076 (5)

Text

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,UNITED STATES F REGULATORY COMMISSION WASHINGTON, D. C. 20555 Docket No. 50-206 JUN 2 0 1990 Mr. R. Dietch Vice President Nuclear Engineering and Operations Southern California-Edison Company 2244 Walnut Grove Avenue Post Office Box 800 Rosemead, California 91770

Dear Mr. Dietch:

This letter is in regard to the failure of the San Onofre Unit No. 1 Salt Water Cooling System on March 10, 1980, as.described in your letter dated March 24, 1980. We are concerned about events such as this where multiple equipment failures occur and we need.additional information con cerning that event to determine what could have been contributing factors and whether remedial measures can be identified which would be of benefit to the industry and the regulatory process. We, therefore, ask that you provide the following information:

1. The south pump, G-13B, shaft failed due to apparent excessive vibration resulting from worn bearings.

A. Was the vibration noticed by the auxiliary operators in the course of shift tours? How often do they tour this area? Are vibration measurements made on these pumps?

B. When was the last time, previous to this event, that the bearings and shaft were inspected?

How often is this performed?

What were the manufacturer's maintenance recommendations in this regard?

C. Have you experienced any similar failures of pump bearings or shafts?

2. We understand that the failure of POV-5 to open at the discharge of the.

north pump was caused-by.a deteriorated 0-ring in the ASCO solenoid valve supplying air to the valve operator.

A. When was the last time, previous to this event, that the 0-ring was inspected or replaced? What was the manufacturer's recommendations in regard to 0-ring inspections or replacement?

8 oo007210

ir. R. Dietch

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2. Continued:

B. Had you experienced any previous difficulty in the operation of this valve or other similar valves and if so what were the corrective measures needed?

C. How often is the non-operating pump placed in service?

D. How often is the automatic start of the pumps tested?

3. We understand that the loss of pumping capability of the auxiliary salt water cooling pump was caused by a leak in the suction line.which allowed air into the line so that the pump lost its prime.

A. When was the last time, previous to this event, that the auxiliary salt water pump was operated? How frequently is it operated?

B. Was the leak associated with a gasket or seal?

How often are gaskets or seals inspected and/or replaced?

4. Please provide an analysis of the-effect of the loss of the Salt Water Cooling System during the design basis loss of coolant accident or the main steam line break inside containment,.whichever is more limiting with regard to heat load on the Component Cooling System and necessary operator actions.

No additional failures need be assumed.

Your analysis should determine the following:

A. The time that it takes for the Component Cooling Water System to reach its design temperature limit with the heatload it will experience during the injection phase and recirculation phase, both with and without containment spray; B.

The time and manpower that it would take to align back-up salt water cooling capability with and without off-site power available; C. *The time and manpower that is used for other manual actions required during this accident, such as shifting from injection to recircula tion and any other operator actions required by your emergency pro cedures; and D. The heat removal capability of the backup salt water cooling provided and a comparison with the component cooling water heat load at the time.

Mr.

JN UMNE 20-1980 Please provide the above information within 30 days of your receipt of this letter.

Sincerely, Original signed by Gus C. Lainas, Assistant Director for Safety Assessment Division of Licensing cc:

cc:

DISTRIBUTION:

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Please provide the above information within 30 days of your receipt of this letter.

Sincerely, Gus C. Lainas, Assistant Director for Safety Assessment Division of Licensing cc:

See next page

Mr. R. Dietch

-4 OWE 2 0 N0 CC:

Charles R. Kocher, Assistant Director, Technical Assessment General Counsel Division Southern California Edison Company Office of Radiation Programs Post Office Box 800 (AW-459)

Rosemead, California 91770 U. S. Environmental Protection Agency David R. Pigott Crystal Mall 12 SSamuel B. Casey Arlington, Virginia 20460 Chickering & Gregory Three Embarcadero Center U. S. Environmental Protection Twenty-Third Floor Agency San Francisco, California 94111 Region IX Office ATTN: EIS COORDINATOR Jack E. Thomas 215 Freemont Street Harry B. Stoehr San Francisco, California 94111 San Diego Gas & Electric Company P. 0. Box 1831 San Diego, California 92112 Resident Inspector C/o U. S. NRC P. 0. Box AA

-Oceanside, California 92054 Mission Viejo Branch Library 24851 Chrisanta Drive Mission Viejo, California 92676 Mayor City of San Clemente San Clemente, California 92672 Chairman Board of Supervisors County of San Diego San Diego, California 92101 California Department of Health ATTN: Chief, Environmental Radiation Control Unit Radiological Health Section 714 P Street, Room 498 Sacramento, California 95814