Modelling the Transport in the Porous Layer of Oxide Films Formed on Material Surfaces in Nuclear Power Plants. Model Extension to More General Conditions

摘要

In this study, the role of the porous oxide film, deposited on top of the primary passive (compact) film to control activity incorporation on the primary circuit surfaces of nuclear power plants (NPPs) is investigated. To serve this purpose, a computerized steady-state transport model, previously developed for a simplified BWR case, has been extended to take into consideration more general high-temperature aqueous and oxide compositions. In practical terms, computationally laborious multi-species reactions for ion, aqueous complexes, precipitates and dissolved gases as well as three types of boundary conditions at the compact film/porous film interface can now be included in the revised model. The model is rendered flexible enough to enable comparison of the effects of various NPP operating conditions, including those prevailing in PWRs. In this report, results calculated with the revised transport model for a BWR system are presented and discussed.