Transmutation of waste actinides in thermal reactors: survey calculations of candidate irradiation schemes

Actinide recycle and transmutation calculations were made for twelve specific thermal reactor environments. The calculations included H2O-moderated reactor lattices with enriched U, recycled Pu, and 233'235U-Th. In addition two D2O reactor cases were calculated. When all actinides were recycled into 235U-enriched fuel, about 10 percent of the transuranic actinides were fissioned per 3-year fuel cycle. About 9 percent of the actinides were fissioned per 3-year fuel cycle when waste actinides (no U or Pu) were irradiated in separate target rods in a U-fuel assembly. When actinides were recycled in separate target assemblies, the fission rate was strongly dependent on the specific loading of the target. Fission rates of 5 to 10 percent per 3-year fuel cycle were observed