ML20147A488

Final ASP Analysis - Calvert Cliffs 2 (LER 318-83-061)

ML20147A488
Person / Time
Site:	Calvert Cliffs
Issue date:	05/26/2020
From:	Christopher Hunter Office of Nuclear Reactor Regulation
To:
Littlejohn J (301) 415-0428
References
LER 1983-061-00
Download: ML20147A488 (1)

Text

LER 318/83-061 Event

Description:

Transient with One LPSI Pump Inoperable Date of Event:

November 7, 1983 Plant:

Calvert Cliffs 2 Summary On November 7, 1983, during monthly surveillance testing of the engineered safety feature actuation system (ESFAS) logic, the 22 low-pressure safety injection (LPSI) pump could not be restarted after being stopped on a recirculation actuation signal (RAS). The trip mechanism on the pump breaker was out of adjustment, causing the breaker to trip free. A plant trip occurred on October 26, 1983, approximately I3 days prior to the discovery of the failed LPSI breaker.

This event was modeled as a transient with one LPSI residual heat removal (RHR) train failed.

The estimated conditional core damage probability for this event is 2.5x10-6. The dominant sequence was an anticipated transient without scram (ATWS) sequence with the failure of auxiliary feedwater (AFW). None of the highest ranking sequences involved the modified branch probability, residual heat removal (RHR).