Advance in and prospect of moderator materials for space nuclear reactors

Abstract

Since 1960s, many countries led by the United States and Russia have done a lot of research on space nuclear reactor power. Moderator is an important functional component in a nuclear reactor operating with a thermal neutron spectrum. This paper reviews the moderation principle, main existing problems, research status as well as main challenges ahead and possible solutions of moderator materials in space nuclear reactor. Aiming at the problems of hydrogen cracking, the low utilization rate of nuclear fuel and hydrogen loss of moderator materials, the assumption of using high entropy alloy hydride as a moderator material is put forward. Moreover, this paper also points out the metal elements suitable for nuclear reactor, while discussing the advantages and disadvantages of several typical elements, hoping to provide a reference for the selection and fabrication of moderator materials. Highlights Sketch the moderating mechanism and the moderator selection principle. Summarize the problems and solutions in the preparation of metal hydride. Summarize the application status of zirconium hydride and yttrium hydride moderator materials. Predict the future development trend and feasible methods of moderator materials.