Modeling particle deposition in the primary circuit of pressurized water reactors for the OSCAR code

Abstract

Particulate corrosion products are generated in the primary system of pressurized water reactors (PWRs) by volume precipitation and by erosion of oxides formed on metal surfaces through their uniform corrosion. The activation of corrosion products, mainly 58Co and 60Co (respectively coming from the activation of 58Ni and 59Co) leads to radiation field growth around the primary system, directly impacting system integrity and the radioprotection of nuclear workers. In order to understand and mitigate contamination by activated corrosion products, contamination predictions can be performed using the OSCAR code, which relies on the development of models to describe the numerous and complex interactions at stake. Particulate corrosion products account for a significant portion of corrosion products, as such the deposition/erosion mechanisms have their importance for the overall computation of surface or volume contamination. The aim of this article is to present an updated and inclusive deposition model for particulate corrosion products by taking into account surface interactions. The impact of the new deposition model on contamination predictions is then evaluated and has enabled to reproduce, for the first time using the OSCAR code, the preferential contamination in 58Co in the cold side of the circuit, measured by gamma spectrometry with the EMECC device on commercially PWRs.