A study of transmutation of long-lived nuclides in fast reactor using new hydride material with high dissociation temperature

Six hydride materials were investigated for eliminating dissociation of hydrogen, which are loaded into a FR. The investigation for the six hydrides was performed for dissociation temperature, melting temperature, capture cross section, production of long-lived nuclides and transmutation performance of minor actinides and long-lived fission products. In the comparison of cross sections and transmutation performances, JENDL-3.2 library was employed, however, JEF-2.2 was also used for ⁸⁴Sr because the cross section is not included in JENDL-3.2. Among the six materials, the investigation indicated that CaH₂ is the most hopeful candidate and ZrV₂H_4.8 is the second. CaH₂ have no problem from the viewpoint of temperature, neutron capture cross section. The transmutation performance of CaH₂, which was the same as that of ZrH_1.6, is the best among the six. If CaH₂ or ZrV₂H_4.8 is employed in a FR, transmutation of long-lived nuclides is improved without introducing safety problem of positive reactivity insertion by hydrogen dissociation.