Start‐up simulation of a thermionic space nuclear reactor system Available to Purchase

The Thermionic Transient Analysis Model (TITAM) is used in this paper to simulate the start‐up of the TOPAZ‐II space nuclear power system in orbit. The start‐up procedures simulated herein are assumed for the purpose of demonstrating the capabilities of the model and may not represent an accurate account of the actual start‐up procedures of the TOPAZ‐II system. The temperature reactivity feedback effects of the moderator, UO₂ fuel, electrodes, coolant, and other components in the core are calculated and their effects on the thermal and criticality conditions of the reactor are investigated. Also, estimates of the time constants of the temperature reactivity feedback for the UO₂ fuel and the ZrH moderator during start‐up, as well as of the total temperature reactivity feedback as a function of the reactor steady‐state thermal power, are obtained.