Probabilistic safety assessment in Canada

The original basis for licensing power reactors in Canada was probabilistic, from which deterministic requirements were derived and developed. The AECB currently regulates in part by imposing unavailability targets on four special safety systems. In recent years, a number of Probabilistic Safety Assessment (PSA) studies have been performed in Canada, although a PSA is not yet formally required yet in licensing. These PSAs are used to derive the fault tree models for special safety systems, to show that their reliability targets are met. A policy and regulatory guides for using PSA in licensing are currently being developed. This article describes the evolution of safety objectives, the current status of PSA, future applications of PSA, and the regulatory aspects of PSA in Canada.