Recent research trends of thorium fuel cycle. Fuel cycle with effective non-proliferative properties and other attractive characteristics. Part 2

Following a previously published report on thorium fuel cycle from the Atomic Energy Society of Japan in 1980, progress made since then is reviewed focusing of studies in chemical, thermodynamic and mechanical properties of thorium oxides including their behavior under irradiation. Variation of melting point of mixed oxides (Th, Pu)O₂ with the thorium oxide/plutonium oxide ratio and thermal conductivity change with temperature (1000 - 1900 K), and some diffusion properties of composing atoms are also described. Fabrication methods of mixed oxide fuel, pellet and particle, are reported. Characteristics of molten salt of thorium fluorides are reported. Possible technologies for reprocessing processes for thorium fuels, as dissolution of thorium oxide by nitric acid solutions, followed by solvent extraction using TBP (THOREX process), including protactinium problem and pyrochemical process, are also reported. Present status for economic assessment for thorium cycle is briefly discussed. (S. Ohno)