ML20156A135

Final ASP Analysis - Pilgrim (LER 293-83-039)

ML20156A135
Person / Time
Site:	Pilgrim
Issue date:	06/04/2020
From:	Christopher Hunter NRC/RES/DRA/PRB
To:
Littlejohn J (301) 415-0428
References
LER 1983-039-00
Download: ML20156A135 (1)

Text

LER 293/83-039 Event

Description:

Trip with HPCI Inoperable Date of Event: July 2, 1983 Plant: Pilgrim Summary During reactor startup surveillance tests on July 2, 1983, the high-pressure coolant injection (HPCI) system was declared inoperable when the HPCI turbine stop valve required more than the normal amount of time to open. A manual scram occurred six days earlier.

Assuming HPCI was inoperable during the scram, the conditional core damage probability estimated for this event is 5.2x10-6. 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).