ML20156A131

Final ASP Analysis - Pilgrim (LER 293-80-080)

ML20156A131
Person / Time
Site:	Pilgrim
Issue date:	06/04/2020
From:	Christopher Hunter NRC/RES/DRA/PRB
To:
Littlejohn J (301) 415-0428
References
LER 1980-080-00
Download: ML20156A131 (4)

Text

November 14, 1980 Inadvertent Opening of Relief Valve at Pilgrim I re sequence was:

e reactor was at full power.

quid nitrogen passing by its ambient air vaporizer froze an line nitrogen supply regulator in place while it was in the fail-en position, due to oversight in system design.

e full pressure nitrogen supply actuated a reactor vessel relief alve's solenoid, which caused the "A" relief valve to open.

e valve was manually cycled 4 to 5 times in an attempt to close but the valve remained open.

e high nitrogen pressure at the relief valve's solenoid prevented osure of the relief valve while the reactor was at operating essure.

e operator reduced core power to 50% and initiated a manual ram.

e reactor continued to depressurize. At 340 psig reactor essure the "A7 relief valve was manually cycled and closed.

ive action:

e relief valve's solenoid actuator supply was switched from trogen to compressed air while changes in the nitrogen system re considered.

placement of the nitrogen regulator valve was considered along th reduction in the nitrogen supply tank pressure and tallation of a nitrogen header relief valve.

purpose of failed system or component:

e nitrogen system provides motive power for opening and closing relief valves (among other control functions) upon automatic as well as manual demands.

e reactor relief valve provides RCS pressure protection.

No No No - auto scram and SBLCS available No 0559 - Actual Occurrence for Inadvertent Opening of Reactor Relief Valve at Pilgrim 1

No 1 Yes 2 No 3 Yes 4 Yes S Yes 6 No 7 Yes 8 Yes 9 Yes 10 NSIC 160559 - Sequence of Interest for Inadvertent Opening of Relief Valve at Pilgrim 1

IC ACCESSION NUMBER: 160559 NO.: 80-080 TE OF LER: November 14, 1980 TE OF EVENT: October 31, 1980 TEM INVOLVED: Pressure relief system MPONENT INVOLVED: Relief valve USE: Excessive nitrogen pressure to valve operator UENCE OF INTEREST: Main steam line break TUAL OCCURRENCE: Inadvertent opening and sticking of a reactor relief valve CTOR NAME: Pilgrim 1 CKET NUMBER: 50-293 CTOR TYPE: BWR SIGN ELECTRICAL RATING: 655 MWe CTOR AGE: 8.4 years NDOR: General Electric CHITECT-ENGINEERS: Bechtel RATORS: Boston Edison Co.

CATION: 4 miles SE of Plymouth, Massachusetts RATION: N/A NT OPERATING CONDITION: Full power E OF FAILURE: Inadequate performance COVERY METHOD: Operational event MENT: See accession 160497 for a similar event at Pilgrim 1, LER 80-69, but with a different cause.