A Point Kinetics Model of the Medical Isotope Production Reactor Including the Effects of Boiling

Previously, a point kinetics model of the Medical Isotope Production Reactor has been presented, which included representations of instantaneous power, delayed neutron precursors, fuel solution temperature, radiolytic gas content, and coolant temperature. This model has been extended to include the effects of a vertically discretized temperature profile with a mixing of heat energy by eddies, boiling, and condensation and an extended model of bubble velocity and radius. It is found that the most striking change to the behavior of the system is caused by the effects of steam, which provides a strong negative feedback that tends to depress average powers in cases where the fuel solution temperature rises above the saturation temperature but can also lead to large, sharp power peaks through steam exiting the system (which can remove a large amount of negative reactivity in a short amount of time). The overall effect, however, does not lead to any unbounded power excursions. Possibilities for further extension of the model include the modeling of the composition of the plenum gas and the modeling of global pressure and its effects.