ML13331B384
| ML13331B384 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 05/20/1980 |
| From: | Ottoson H SOUTHERN CALIFORNIA EDISON CO. |
| To: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| Shared Package | |
| ML13331B385 | List: |
| References | |
| NUDOCS 8005230477 | |
| Download: ML13331B384 (2) | |
Text
Southern California Edison Company P.O. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 May 20, 1980 U. S. Nuclear egulatory Commission Region V Office of Inspection and Enforcement Suite 202, Walnut Creek Plaza 1990 North California Boulevard Walnut Creek, California 94596 Attention:
Mr. R. H. Engelken, Director DOCKET No. 50-206 SAN ONOFRE -
UNIT 1
Dear Sir:
This letter describes a reportable occurrence involving the failure of portions of the Nuclear Instrumentation System.
Submittal is in accordance with the reporting requirements stipulated in Section 6.9.2(b) of Appendix'A to the Provisional Cperating License DPR-13.
On April 20, 1980 at 2130 during the preliminary steps of the refueling process after the refueling canal had been flooded, Source Range Nuclear Instrumentation channel 1202 was observed to be indicating erratically. At 2345 on the same day Source Range Nuclear Instrumentation channel 1201 high voltage failed.
Although an installed spare Source Range Nuclear Instrument ation channel and two intermediate range channels continued to provide visual indication of neutron level, audible indication requIired by Section 3.8.A.2 of the TILchnical Specifications was not in service.
In accordance with the requirements of Technical Specification 3.8.A.7 refueling operations were stopped and repairs initiated. At 0925 on April 21, 1980 the neutron detectors from the spare channel were connected to channel 1201 restoring audible indication.
8005 2830 9
Mr.
R. H. Engelken May 20, 1980 Page 2 Concurrent with the failure of channel 1201 a Reactor Cavity Hi Level Alarm had been received.
Subsequent investigation revealed that leakage had occurred through the reactor vessel to cavity seal flange allowing water to enter the channel 1201 and 1202 neutron detectors and preamps. The refueling canal was drained and the source range channels 1201 and 1202 repaired on April 23, 1980. After conpletion of repairs refueling operations were resumed.
Should you have any questions regarding this matter, please contact me.
Sincerely, H. L. Ottoson Manager of Nuclear Operations cc:
Director, Office of Inspection and Enforcement (30)
Director, Office of Management Information & Program Control (3)
Director, Nuclear Safety Analysis Center (1)