[en] The open-cycle gas-core fission reactor (GCR) has been mentioned as one of the most promising advanced propulsion schemes that could readily meet the objectives of the space exploration initiative of sending a manned mission to Mars in the early part of the next century. The principle of operation in this system involves a critical fissile core in the form of a gaseous plasma that heats, through radiation, a hydrogen propellant, which is expelled through a nozzle, thereby converting thermal energy into thrust, as illustrated in Fig. 1