Radioactive releases from candu power reactors during an end-fitting failure postulated accident

Abstract

An accident scenario in which the end-fitting of one channel of the Pickering-B, Canadian Pressurized Heavy Water Reactor (CANDU) is assumed to fail completely is considered. All of the 12 bundles of the channel are assumed to be discharged to the fuelling-machine vault and onto the floor. Three cases are analysed; the case of intact bundle, bundle broken into separate intact fuel pins and broken bundle with broken pins. Release of 1311and Xe+ Kr to the atmosphere are estimated for both cases of intact and impaired containment using AECL computer codes HOTSPOT, CURIES, FIREBIRD and PRESCON. For conservatism, the channel with the maximum power was used in the analysis. The activity released to the environment in both events of intact containment (single failure) and impaired containment (dual failure) was estimated to be below the permissible regulatory limits. How-ever, the activity released in the dual failure case is much higher than that for the single failure.