The research presented in this paper is part of a project to help develop a risk-informed approach to the design optimization and licensing of a sodium-cooled fast reactor (SFR). The objectives of this research include analyzing accident scenarios that occur in SFRs and assessing their offsite consequences.
The reference plant design is similar to the ABR-1000 design using a 1000 MWth pool-type design with both metallic and oxide fuels and a dry containment. This paper uses a code developed at the Ohio State University called RCS to analyze the reactor kinetics and thermal-hydraulic behavior of accident scenarios and MELCOR to investigate radionuclide transport, deposition, and environmental releases. Offsite dose consequences are calculated at one-mile over a 24-hour time period using a spreadsheet for 95th percentile meteorology based on the approach found in Regulatory Guide 1.145. The WinMACCS code is also used to determine the probability of early fatality consequences one mile from the site boundary and latent cancer fatalities within ten miles.
Several accident scenarios were investigated including those with non-energetic events, energetic events, and core uncovery situations. For each scenario, analysis was performed for when the containment was both failed and intact and whether or not a gross or limited failure of the primary system had occurred. This analysis and resulting offsite dose consequences were then compared to the Frequency-Consequence curve of the NRC’s Technology Neutral Framework (TNF).