Transient Analyses for a Molten Salt Transmutation Reactor Using the Extended SIMMER-III Code

Recent developments extending the capabilities of the SIMMER-III [1, 2] code for the dealing with transient and accidents in Molten Salt Reactors (MSRs) are presented. These extensions refer to the movable precursor modeling within the space-time dependent neutronics framework of SIMMER-III, to the molten salt flow modeling, and to new equations of state for various salts. An important new SIMMER-III feature is that the space-time distribution of the various precursor families with different decay constants can be computed and took into account in neutron/reactivity balance calculations and, if necessary, visualized. The system is coded and tested for a molten salt transmutater. This new feature is also of interest in core disruptive accidents of fast reactors when the core melts and the molten fuel is redistributed.