Calculation of a materials relocation experiment simulating a core discruptive accident condition in fast breeder reactors Original Research Article

This paper describes an interpretation of the SIMBATH (Simulationsexperimente in Brennelementattrapen mit Thermit) experiments that use the Simmer-II code. A series of SIMBATH experiments has aimed at simulating fuel pin disintegration and following materials relocation in the test sections of a single pin to 37-pin bundles. In the calculation, three modifications were incorporated into the Simmer-II code. With these modifications, the calculation showed good agreement with the experimental measurements with respect to the void region propagation in sodium flow and the molten materials relocation leading to flow blockage. A set of parametric calculations has clarified the range of applicability of parameters for materials relocation and flow blockage formation. The particle radius rp in blockage regions and the multiplier for particle viscosity (PARVIS) are recommended to be rp ⪆ built12Dh and 0.001 Pa s ⪅ PARVII ⪅ Pa s respectively.