Delayed Station Blackout Event and Nuclear Safety

Abstract EN

The loss of off-site power (LOOP) event occurs when all electrical power to the nuclear power plant from the power grid is lost.

Complete failure of both off-site and on-site alternating current (AC) power sources is referred to as a station blackout (SBO).

Combined LOOP and SBO events are analyzed in this paper.

The analysis is done for different time delays between the LOOP and SBO events.

Deterministic safety analysis is utilized for the assessment of the plant parameters for different time delays of the SBO event.

Obtained plant parameters are used for the assessment of the probabilities of the functional events in the SBO event tree.

The results show that the time delay of the SBO after the LOOP leads to a decrease of the core damage frequency (CDF) from the SBO event tree.

The reduction of the CDF depends on the time delay of the SBO after the LOOP event.

The results show the importance of the safety systems to operate after the plant shutdown when the decay heat is large.

Small changes of the basic events importance measures are identified with the introduction of the delay of the SBO event.