Study on transmutation technology of Long-Lived-Fission-Products (LLFP) using commercial fast reactors; Loading type of LLFP target assembly and transmutation performances of cores designed in FS phase-II

Naganuma, Masayuki  ; Aida, Tatsuya*; Hayashi, Hideyuki

In the Feasibility Study in Japan (FS), transmutation technology of LLFP using commercial fast reactors has been studied to reduce the environmental burden. In this report, loading type of LLFP target assembly, transmutation performances of FS designed cores and capability of transmutation core with high SF (transmutation / production ratio) are studied. Design studies for two loading types cores (in-core and ex-core loading type) were conducted for comparison. The in-core loading type core was found to decrease LLFP inventories significantly, thus, that was selected as the reference of FS. For FS phase-II designed cores, LLFP transmutation performances were evaluated. Every core was confirmed to have the capability to attain SF 1.0. Then, we conducted sensitivity evaluations of design conditions to SF for transmutation core with high SF. Since sensitivities of every condition were found to be small, we concluded that large SF may be impossible for the commercial reactors.