A study on the production and separation of transuranium elements

In advance of the experiments, build up of transuranium nuclides by multiple capture of neutrons in natural uranium was computed for the neutron flux expected in JMTR (Japan Material Testing Reactor). The yields of fissile Pu and 252Cf, the important nuclear fuel and the most useful heavy transuranium nuclide respectively, were discussed with respect to the stimulative contribution of epithermal neutrons. Next, the natural uranium pellets were irradiated up to 1,500 MWD in JMTR. After irradiation each transuranium element was separated and the isotopic abundances of them were determined radiochemically. Taking into account the self-shielding effect in the sample, the yields of the nuclides under the actual operation condition of the reactor were computed. The agreement between the computation and the experimental results was found when the thermal flux is 9x1013 n/cm2 sec and the ratio of thermal flux to the epithermal one is one tenth. (auth.)