LLFP Transmutation Performance in Sodium,Pb-Bi and He Cooled Fast Reactors

Takaki, Naoyuki; Naganuma, Masayuki  ; Mizuno, Tomoyasu

The performance of Sodium, Pb-Bi and He cooled fast reactors in terms of LLFP transmutation has been investigated from view points of nuclear, thermal and material characteristics. The targeted LLFP are two elements as I and Tc. Transmutation performance target set here is simultaneous achievement of the ratio of transmutation rate / production rate of 1.0 and transmutation ratio of 30% at the removal. In the thermal hydraulic analysis for the cores loaded with LLFP assemblies, it is turned out that the hydrogen penetration is still the most significant design restriction of the required coolant flow rate. MOX fueled sodium cooled and Pb-Bi cooled reactors loaded with LLFP assemblies in the core periphery region have a potential to transmute self-produced LLFP at 30% of transmutation rate without significant design modification. As for He cooled reactor, the transmutation rate is below the target value in this study.