ML20168A705

Final ASP Analysis - Pilgrim (LER 293-75-034)

ML20168A705
Person / Time
Site:	Pilgrim
Issue date:	06/16/2020
From:	Christopher Hunter NRC/RES/DRA/PRB
To:
Littlejohn J (301) 415-0428
References
LER 1975-034-00
Download: ML20168A705 (4)

Text

ember 13, 1975 s of Offsite Power and a Relief Valve Sticks Open at Pilgrim 1 e sequence was:

actor was undergoing a routine shutdown when a turbine trip occurred (no rea-s given for the turbine trip). This caused the startup and auxiliary 345 kv to de-energize (again reason unspecified resulting in a loop), and the reactor p.

esel generators started and re-energized the safety related buses.

ef valve .(203-2B) opened for pressure control.

alve stuck open until the reactor pressure fell to approximately 300 psig.

ilure was attributed to steam cutting the pilot valve assembly, which sed the pressure on the actuating side of the second stage piston, thereby ng the closing forces on this piston.

action:

action was not discussed in the LER.

pose of failed system or component:

artup. buses provide station power when the unit is not generating power.

valves provide for pressure control.

ity of system per WASH 1400:

• Loop: _10-3 /D following trip.

ity of component per WASH 1400:

• PORV failure to close: 10-2 /D ilabilities are in units of per demand D-1 . Failure rates are in r hour HR-1

xiliary buses

_ ________________I____ ___

No No No - 2 relief and 2 safety valves remained operational

- provided a.c. power is restored before RCIC supply steam is expended.

-No

- see above two comments 106616 - Actual Occurrence of Loss of Off site Power and a Relief Valve Sticks Open at Pilgrimd 1

Manually Driven in Cooling Damage No 1 Yes 2 No 3 Yes 4 Yes 5 No 6 Yes 7 Yes 8 No 9 Yes 10 No 11 Yes 12 Yes 13 Yes 14 Yes 15 IC 106616 - Sequence of Interst for Loss of Offsite Power and a Relief Valve Sticks Open at Pilgrim 1 A relief valve-stuck open.

NUMBER: 106616 eptember 14, 1975 September 13, 1975

electric power, reactor pressure relief system VED: startup and auxiliary transfers, relief valve trip (electric), mechanical failure (relief valve)

EREST: loss of offsite power CE: loss of offsite power and a relief valve sticks open at Pilgrim 1 Pilgrim 1 50-293 BWR AL RATING: 655 Mftq 3.3 yr l Electric EERS: Bechtel ton Edison iles SE of Plymouth, Mass.

CONDITION: undergoing a routine shutdown TYPE OF FAILURE: (a) inadequate performancý; (b) failed to start; emade inoperable; Q~/ag~~

D: operational event