Capillary Pumped Passive Reactor for Space Power

摘要

Advanced ground-based reactor designs, such as AP-600, AP-1000, SBWR, etc. feature the passive emergency core cooling via natural circulations to promote the passive safety of the reactor, reduce active mechanical elements such as the emergency core cooling system (ECCS) pumps, and minimize the need for human intervention in the event of accident. For space-based reactors, e.g. the long-endurance Lunar, Mars missions or the Jupiter Icy Moon Orbiter (JIMO) program under Project Prometheus, passive safety and unattended operation are even more desirable. The Applied Research Laboratory (ARL) of Penn State has developed the concept for the “capillary pumped reactor” (CPR) to facilitate passive cooling of the space reactor. In the sub-g or micro-gravity environment of space, gravity-driven natural circulation is not effective nor an option. On the other hand, the high surface tension of some liquid metals, particularly molten lithium, may be utilized to create the “capillary flow” that would remove heat from the reactor under both the normal and accident conditions without the use of mechanical devices such as the electromagnetic (EM) pumps. With the capillary wicking structure and the evaporation/condensation cycle similar to the heat-pipe operation, CPR systems have the potential to function effectively in both the gravitational fields near celestial bodies and more effectively in the micro-gravity of space - a unique attribute to the capillary pumped systems. System models of the passive CPR concept are presented as follows, along with the introduction of a “hybrid” space nuclear power concept that flexibly switches between the passive and active modes as the space mission requires.