Performance and radiological analyses of a space reactor power system deployed into a 1000–3000 km earth orbit

Abstract

This paper presents the results of performance and radiological analyses of a space reactor power system to support space-based, radar satellites in a 1000–3000 km orbit for global civilian air and ocean traffic control. The power system with six primary and secondary loops to avoid single point failures in reactor cooling and energy conversion employs a sectored, liquid NaK-78 cooled fission reactor that has a negative temperature reactivity feedback and SiGe thermoelectric energy conversion modules, nominally generating 37.1 kW e for up to 6 years. The reactor nominally generates 1183.6 kW th at an exit temperature of ∼992 K. Thermoelectric–electromagnetic (TEM) pumps circulate the liquid NaK-78 in the primary and secondary loops and passively remove the decay heat from the reactor core after shutdown. The system parameters during the startup and shutdown transients and nominal steady-state operation are calculated. The effects of the period of incrementally inserting external reactivity on the system parameters during nominal operation are also investigated. The radioactivity buildup in the reactor during nominal operation up to 6 years and the decay in radioactivity after shutdown and as a function of storage time in orbit up to 1000 years are calculated.