Integral severe accident codes: IMPACT/SAMPSON

SAMPSON (Severe Accident analysis code with Mechanistic, Parallelized Simulations Oriented toward Nuclear Fields) is a code included in the IMPACT (Integrated Modular Plant Analysis and Computing Technology) code system, which was developed under the sponsorship from the Japanese Ministry of Economy, Trade and Industry. It is owned and developed by the Institute of Applied Energy (IAE), Japan and it has restarted substantial development after the occurrence of the accident at the Fukushima Daiichi Nuclear Power Station. The SAMPSON code contains lumped parameter and 3D modules that can analyze the severe accident phenomena occurring in a nuclear power plant from the fuel heat up and melt to the fission product transport to the reactor building and environment. SAMPSON was developed as a combination of various solid experiences in computer codes for nuclear plant safety analysis. Regarding thermal-hydraulics of the reactor coolant systems, the thermal hydraulics analysis module is designed based on the RELAP code, for the core degradation, it takes advantage of the mechanistic concepts contained in the SIMMER code for multiphase and multicomponent analysis. Finally, containment vessel pressure analysis traces back to the solid formulation of the CONTAIN code for the containment analysis. In addition, it features several three-dimensional codes developed at IAE for the analysis of the lower head and penetration failure, debris spreading and MCCI in a pedestal, and a module for the analysis of the suppression pool temperature distribution.