Probabilistic Safety Assessment of Support Systems for CANDU Stations

Atomic Energy of Canada Limited (AECL) has performed probabilistic safety assessments (PSAs) of Canada deuterium uranium (CANDU) reactor support systems since 1975. AECL’s experience in the use of PSAs on support systems and the application of the PSA for the CANDU 3 are described. The PSA work reviews support system failures such as loss of service water and loss of instrument air as initiating events during full power and during plant shutdown conditions. The design changes resulting from this work, with respect to prevention of loss-of-coolant accidents and maintaining a long-term heat sink, are described. The use of PSAs is being initiated early in the design of the next-generation CANDU reactor (CANDU 3) to avoid the possibility of design changes and backfits during the construction phase of the project.