ML13324A935
| ML13324A935 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 08/21/1986 |
| From: | Lear G Office of Nuclear Reactor Regulation |
| To: | Baskin K Southern California Edison Co |
| References | |
| NUDOCS 8608250105 | |
| Download: ML13324A935 (3) | |
Text
Docket No.:
50-206 Mr. Kenneth P. Baskin, Vice President Nuclear Engineering Safety and Licensing Department Southern California Edison Company 2244 Walnut Grove Avenue P.O. Box 800 Rosemead, California 91770
Dear Mr. Baskin:
SUBJECT:
SAN ONOFRE 1 - CLARIFICATION OF LONG-TERM SERVICE (LTS) SEISMIC SAFETY EVALUATION REPORT On July 11, 1986, the NRC issued to you a safety evaluation report on the LTS Seismic reevaluation of San Onofre Unit 1. In subsequent discussions with members of your staff, it was apparent that one section of our evaluation was confusing and could be misinterpreted. This was on page 15 of the evaluation, discussing the review of effects of failure non-seismically qualified equipment.
The sentence read:
"The effects of failure of other non-seismically qualified equipment on the plant were previously evaluated as discussed in a November 3, 1984 (Ref. 31) submittal from the licensee."
A more complete discussion should have been included to properly characterize the reviews done by both SCE and the NRC in this area.
The November 3, 1984 evaluation assessed the effects upon those systems, structures, and components which were included in the return-to-service (RTS) that might be caused by failure of systems, structures and components whose seismic qualification was deferred to LTS. Other evaluations have previously been performed of pipe break effects and flooding. In addition walkdowns were done to look for fragile components that might be affected by failure of other equipment. Seismically induced settlement of equipment on backfill soil, both safety-related and non safety-related, was evaluated to ensure that the equipment would not overturn onto safety-related equipment.
8608250105 860821 PDR ADOCK 05000206 IP PDR
-2 Two possible adverse interactions were identified by these reviews:
the condensate storage tank and the ventilation stack. Since failure of the ventilation stack might affect safety-related equipment, it was qualified for the earthquake and is included in the scope. As discussed in the July 11, 1986 SER, the effects of failure of the condensate storage tank were evaluated and determined to be acceptable.
A specific interaction study of all components within the complete seismic scope from failure of any other equipment was not performed. However, such a study was not considered necessary by the staff based on the extensive upgrading that has been completed and on the other studies that have been done as noted above. Therefore, the staff concluded in the safety evaluation that the effects of failure of non-qualified equipment had been adequately considered.
The above discussion is provided to clarify the extent of the review of this issue; the conclusions of our July 11, 1986 evaluation are not affected.
George E. Lear, Director PWR Project Directorate #1 Division of PWR Licensing-A cc:
See next page Office:
V/PAD#1 PUP Surname:
EMcKenna/1p RDudley GLear Date:
08/.1/86 08/1&/86 08/ti /86
Distribution Copies:
Docket No. 50-206 NRC PDR Local PDR PAD#1 r/f PAD#1 p/f TNovak, Actg. DD NThompson, DHFT OGC-Bethesda EJordan BGrimes JPartlow EMcKenna RDudley GLear PShuttl eworth ACRS (10)