Small space nuclear reactors

Space nuclear power systems in the range of 10-30 kWe are discussed in this paper. It has been thought advisable to widen the basis for future technical choices within the French preliminary studies in this low power range. In addition to a reference Brayton cycle, NaK-cooled, fast spectrum, 930 K reactor system, a 1130 K direct cycle, gas-cooled, ZrH moderated reactor concept has been investigated. Gas cycle adaptations for core temperature conditioning have been studied and have already enhanced the Brayton converter utilization. Following a recent U.S. proposal of high power level, light water moderated reactor space power systems, a research work for applying this technique to small reactors is being performed. The Brayton cycle can offer adequate temperature conditions for that. Relevant conversion data are presented. Because of the use of a main low temperature, pumped-loop radiator, a multiple tubes support structure could be advantageously used for the heat rejection. Comparative results are given