High-abundance Pu-238 produced by nuclear transmutation of liquid MA fuel in reactor

The feasibility of mass producing high-abundance ²³⁸Pu using liquid fuel containing minor actinides (MA) in a reactor is discussed. A chemically stable liquid solution or molten salt with MA dissolved, is evenly distributed in the inner or outer region of the reactor core to ensure that the MA materials receive sufficient neutron irradiation and achieve a high transmutation rate. The transmutation products of ²⁴¹Am or ²³⁷Np are mainly ²³⁸Pu and fission products. After being burned, the liquid fuel is extracted from the reactor and separated in a reprocessing plant to obtain high-abundance ²³⁸Pu material.

To maximize the abundance of ²³⁸Pu in reaction products, a thorium-based molten salt fast reactor was adopted. Its inner and outer regions of core are loaded with molten salts LiF + ThF₄+XF₄ and LiF + ThF₄, where X is ²³³U or ²³⁵U. Fluoride salts of ²⁴¹Am, ²³⁷Np, or TRU-MAs (a mixture primarily composed of ²⁴¹Am and ²³⁷Np) are added to one of these molten salts. Depending on the different driving fuels and MA targets, the annual output of ²³⁸Pu ranges from 6.9 to 130.2 kg, with abundances varying from 67.7 % to 99.4 %. The annual transmutation rates for single nuclide ²⁴¹Am or ²³⁷Np, can reach up to 21.4 % or 20.0 %.