ML20147A483

Final ASP Analysis - Calvert Cliffs 1 (LER 317-82-054)

ML20147A483
Person / Time
Site:	Calvert Cliffs
Issue date:	08/31/1982
From:	Christopher Hunter Office of Nuclear Reactor Regulation
To:
Littlejohn J (301) 415-0428
References
LER 1982-054-00
Download: ML20147A483 (1)

Text

LER 317/82-054 Event

Description:

Transient with One Turbine-Driven AFW Pump Inoperable Date of Event: August 31, 1982 Plant: Calvert Cliffs 1 Summary On August 31, 1982, while a surveillance test was being performed, the governor linkage of auxiliary feedwater (AFW) pump 12 vibrated loose, rendering the pump inoperable. A loose nut connecting the governor lever to the connecting rod backed off its pin, causing the pin to come out.

The linkage was repaired and returned to service approximately 45 minutes later. Other AFW pumps were checked for loose governor linkage nuts, but all were tight.

A plant trip occurred on August 22, 1982, nine days prior to the discovery of the faulted AFW pump. This event was modeled as a transient with one AFW pump assumed to be inoperable.

The estimated conditional core damage probability for this event is 2.9x10-6. The dominant sequence was an ATWS sequence involving the failure of AFW given ATWS. The second highest contributor involved a successful reactor trip, failure of AFW, failure of main feedwater, and failure of feed and bleed.