ML20156A214
| ML20156A214 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 06/04/2020 |
| From: | Christopher Hunter NRC/RES/DRA/PRB |
| To: | |
| Littlejohn J (301) 415-0428 | |
| References | |
| LER 1980-006-00 | |
| Download: ML20156A214 (4) | |
Text
March 24, 1980 Total Loss of Saltwater Cooling System at San Onofre I ilure sequence was:
With the reactor at full power and south saltwater cooling (SWC) pump G-13B in operation, G-13B shaft failed due to excessive vibration from worn bearings.
This resulted in low flow and low discharge pressure alarms in the control room and auto start of north SWC pumps G-13A.
North pump G-13A discharge valve failed to open due to an O-ring Failure caused by desiccant in the instrument air lines. This resulted in no flow from either pump.
Auxiliary saltwater cooling pump G-13C was manually started from the control room but failed to develop sufficient flow because of insufficient prime, and the pump was shut down.
The screen wash pumps were manually started from the local panel and valves manually aligned to discharge to the bottom component cooling water (CCW) heat exchanger, which reestablished CCW cooling.
Adequate prime was restored to SWC pump G13-C and the pump was placed in service.
ctive action:
North SWC pump valve POV-5 was opened and the north SWC pump placed rvice. The auxiliary SWC pump surveillance testing was increased once per week to daily durjng low tide conditions.
n purpose of failed system or component:
The salt water cooling system provides essential cooling flow to omponent cooling water system (RC pumps, RHR pumps, charging pumps, ulation heat exchanger).
to open due to inadequate flow to component prime cooling water heat exchangers No No - but reactor shutdown and natural circulation cool-ing required without com-ponent cooling water; turbine cycle cooling still available No - turbine-driven AFW pump apparently self cooled No 55475 - Actual Occurrence for Loss of Saltwater Cooling System at San Onofre 1
Screen Wash Pumps Manual Reactor Auxiliary Feedwater Potential Sequence Provide Adequate Shutdown, RCPS and Secondary Heat Severe No.
CCW Cooling Tripped Removal Core Damage No No 7ý5ý9' Yes NSIC 155475 -' Sequence of Interest for Loss of Saltwater Cooling System at San Onofre 1
NO.: 80-006 OF LER: March 24, 1980 E OF EVENT: March 10, 1980 EM INVOLVED: Saltwater cooling system PONENT INVOLVED: South pump, north pump discharge valve, auxiliary pump SE: Pump and valve failures UENCE OF INTEREST: Loss of service water system AL OCCURRENCE: Loss of service water system TOR NAME: San Onofre 1 KET NUMBER: 206 CTOR TYPE: PWR GN ELECTRICAL RATING: 436 MWe TOR AGE: 12.7 years DOR: Westinghouse HITECT-ENGINEERS: Bechtel RATORS: Southern California Edison ATION: 5 miles south of San Clemente, California ATION: N/A T OPERATING CONDITION: Full power OF FAILURE: Inadequate performance; failed to start OVERY METHOD: Operational event MENT: