Volatile fission products transfer from hot sodium pools

Abstract

This study focuses on the release of the most relevant volatile fission products from the hot sodium pools. From an exhaustive review of the open literature, a critical review of a model based on the film theory and its estimates in comparison to data from the NALA experimental program has been conducted. Due to certain assumptions embedded in the approach, the fitting-to-data transport coefficients derived and some inconsistencies found between its formulation and the reported estimates, an alternate approach including other phenomena anticipated in the scenario is here proposed. Based on diffusive and convective mechanisms in the gas phase, the assumption of the analogy between heat and mass transport (HMT) and the ideal-dilute solutions laws to set the fission products concentration at the Na pool interface, a good agreement has been found with experimental data, which mean a substantial enhancement of qualitative and quantitative predictability while maintaining a conservative nature.