ML13330B393
| ML13330B393 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 09/14/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML13330B392 | List: |
| References | |
| NUDOCS 8809270067 | |
| Download: ML13330B393 (2) | |
Text
ENCLOSURE 1 SAFETY EVALUATION REPORT DOCKET NO. 50-206 SAN ONOFRE NUCLEAR GENERATING STATION, UNIT 1 GENERIC LETTER 83-28, ITEM 4.5.2 REACTOR TRIP SYSTEM RELIABILITY, ON-LINE TESTING INTRODUCTION AND
SUMMARY
Generic Letter 83-28 was issued by NRC on July 8, 1983, indicating actions to be taken by applicants and licensees based on the generic implications of the Salem ATWS events. Item 4.5 states a staff position which requires on-line functional testing of the reactor trip system, including independent testing of the diverse trip features of the reactor trip breakers, for all plants. Item 4.5.2 requires applicants and licensees with plants not currently designed to permit this periodic on-line testing to justify not making modifications to permit such testing. By letters dated November 28, 1983, January 12, 1984, October 1, 1,984, June 3, 1987 and November 13, 1987, the licensee, Southern California Edison Company, responded to the staff position regarding Item 4.5.2 of Generic Letter 83-28. Our review of these responses finds them to be acceptable.
EVALUATION The licensee states that the San Onofre 1 plant is not designed to allow on-line testing of the Reactor Trip System. The San Onofre 1 design does not include bypass breakers, which are necessary to permit on-line tripping of the reactor trip breakers without tripping the reactor. The licensee states that installation of the equipment required to modify the plant would be very difficult to accomplish because of the lack of space in the switchgear room, and that the San Onofre 1 design provides simultaneous operation of both shunt and undervoltage trip attach ments. The licensee also states that maintenance and inspection of the RTBs revealed no indications of failure to trip during the past 19 years of operation, and that the RTS breakers are fail-safe since their control power is derived from the same 125 volt DC bus that supplies the control rod stationary grippers.
SO9270067 8:=:0914 PIR ADOCeK 05000206 P
PDC.
- 2 CONCLUSION The staff finds that the licensee's justification for not installing the modifi cations necessary to permit on-line testing of the Reactor Trip System at San Onofre 1 is acceptable, in view of the cost and difficulty of installing the necessary equipment, the fact that both the undervoltage and shunt trip attachments are actuated upon demand for reactor trips, the fact that the reactor trip system breakers are fail-safe since their control power is derived from the same 125 volt D.C. bus that supplies the control rod drive stationary grippers, and the satis factory history of reactor trip reliability at the plant.