ML20156A136

Final ASP Analysis - Pilgrim (LER 293-83-052)

ML20156A136
Person / Time
Site:	Pilgrim
Issue date:	06/04/2020
From:	Christopher Hunter NRC/RES/DRA/PRB
To:
Littlejohn J (301) 415-0428
References
LER 1983-052-00
Download: ML20156A136 (1)

Text

LER 293/83-052 Event

Description:

Trip with HPCI Inoperable Date of Event: September 23, 1983 Plant: Pilgrim Summary While monthly surveillance of the high-pressure coolant injection (HPCI) system was being performed during steady-state operation on September 23, 1983, the HPCI was declared inoperable when the HPCI motor operated valve 2302-3 failed to open. Fourteen days earlier, on September 9, 1983, a scram occurred during surveillance testing.

Assuming HPCI was failed at the time of the scram, a conditional core damage probability of 5.2x10-6 is estimated. The dominant sequence involved a transient initiator followed by successful reactor shutdown, failure of the power conversion system, failure of two safety relief valves (SRVs) to close, unavailability of HPCI, and failure of the automatic depressurization system (ADS).