Review of R and D of thorium molten-salt reactor

Nuclear power will be used continuously as low-carbon energy for a sustainable society. On the other hand, prime attention is inclined to thorium molten-salt reactor (MSR) in recent years due to necessity for radioactive waste disposal, nuclear non-proliferation ('world without nuclear weapon') and higher safety of nuclear power. Thorium MSR is a type of liquid-fueled reactor utilizing thorium as fertile with some fissile materials contained in molten-salt. Research and development (R and D) of MSR started in the 1950s at Oak-Ridge National Laboratory (ORNL) for aircraft reactors. R and D activities were later extended to develop civilian power reactors using thorium, a concept which was completed in the 1970s. Nonetheless, technical problems still remained, such as temperature reactivity coefficient, material corrosion, and tritium permeation at heat exchanger. Since the 1980s several R and D activities to circumvent these problems have been done inside and outside ORNL. The problems relating to thorium MSR and recent R and D activities will be introduced in this paper. (author)