ML20156A130

Final ASP Analysis - Pilgrim (LER 293-80-079)

ML20156A130
Person / Time
Site:	Pilgrim
Issue date:	06/04/2020
From:	Christopher Hunter NRC/RES/DRA/PRB
To:
Littlejohn J (301) 415-0428
References
LER 1980-079-00
Download: ML20156A130 (4)

Text

SIC Accession Number: 160926 ate: October 31, 1980 le: Stuck Open Relief Valve at Pilgrim 1 e failure sequence was:

. With the reactor at full power, a scram occurred due to main steam line high radiation.

. To control pressure, "C" relief valve opened for 1 minute and closed successfully. HPCI and RCIC were placed in full flow test.

. The MSIVs had closed during the event when the reactor depressurized beyond the MSIV closure set point of 880 psig. The "D" relief valve was opened to reduce the reactor pressure enough to be able to reset the scram and reopen the MSIVs.

. The "D" relief valve stuck open.

. Repeated attempts to energize/deenergize the relief valve solenoid valve from the control room failed to close the "'D" relief valve and the plant depressurized to 20 psig.

orrective action:

. The plant was shutdown and the valve assembly removed and tested.

The utility concluded that the probable cause of the failed valve was scoring on the main piston.

. A spare valve assembly and solenoid were installed and the unit was returned to service.

. The damaged valve was repaired.

esign purpose of failed system or component:

The pressure relief system provides overpressure protection for the S.

signal control depressurization to Core 20 psig Damage No - safety systems available for core cooling if required d

'No No NSIC 160926 - Acutal Occurrence for Stuck-Open Relief Valve at Pilgrim 1

Damage No 1 Yes 2 No 3 Yes 4 Yes 5 Yes 6 No 7 Yes 8 Yes 9 Yes 10 NSIC 160926 - Sequence of Interest for Stuck Open Relief Valve at Pilgrim 1

ACCESSION NUMBER: 160926 NO.: 80-079 OF LER: October 31, 1980 OF EVENT: October 1, 1980 EM INVOLVED: Pressure relief system PONENT INVOLVED: Relief valve E: Mechanical failure in valve operator ENCE OF INTEREST: Main steam line break AL OCCURRENCE: Stuck open relief valve TOR NAME: Pilgrim 1 ET NUMBER: 50-293 TOR TYPE: BWR GN ELECTRICAL RATING: 655 MWe TOR AGE: 8.3 years OR: General Electric HITECT-ENGINEERS: Bechtel ATORS: Boston Edison Co.

TION: 4 miles SE of Plymouth, Massachusetts ATION: N/A T OPERATING CONDITION: Full power OF FAILURE: Inadequate performance OVERY METHOD: Operational event ENT: