Development of the transient analysis code for the space thermionic reactor

The Russian TOPAZ II reactor is a single-cell thermionic, Zirconium hydride moderated, epi-thermal design with a highly enriched UO₂ fuel. The waste heat from the reactor is removed by the eutectic sodium-potassium coolant, and given off to the space by a radiator. According to the special structure of this space power system, a new transient analysis code(TASTIN) is developed to analysis its thermal hydraulic characters during steady state, transient events and some typical accidents. The steady state calculation results are in good agreement with the design values. During the partial loss of flow accident, in a certain period of time, temperature of each layer material and coolant are lower than the safe limits. It proved that the TASTIN program can be achieved on the system safety analysis of space thermionic reactor. (authors)