A Study of the Effectiveness for Response to Loss of Class IV Power of One Standby Class III Generator Operating in a Continuous or Test Cycle Mode

Abstract

This paper presents the results of a reliability study that models, evaluates and compares the effectiveness for response to loss of Class IV power (LOCLIV) of a single available Class III standby generator (SG) at an operating CANDU plant. The modelling is based upon operating and licensing considerations at Point Lepreau Generating Station (PLGS) and is applicable to cases where one of its two SG's is out of service for maintenance when a LOCLIV event occurs. The different licensing requirements for two modes of SG operation, either continuous or in a series of successive testing cycles when the reactor is shut down or operating at power, have been modelled. Techniques have been developed to convolve the modelled probability of occurrence of a LOCLIV at a particular time instant with the probability of successful SG response and Class III system reconfiguration from the existing operational state to the required safety response state. The concepts, techniques and models developed to measure the response to a LOCLIV event by an SG in continuous or cyclic mode of operation are described in this paper.