Design Study on Core and Fuel Properties of Sodium Cooled Fast Reactor (Mixed Oxide Fuel Core); Results in JFY2003

Naganuma, Masayuki  ; Ogawa, Takashi; Takaki, Naoyuki; Mizuno, Tomoyasu

Sodium cooled fast reactor (mixed oxide fuel core) is one of promising candidates in Feasibility Study on Commercialized Fast Reactor Cycle System in Japan (FS). Its design study has been conducted thorough FS. In JFY2003's study, two types of core were evaluated. One is "Compact type" that follows a conventional type, and the other is "High internal conversion type (HIC type)". The HIC type is core concept aiming to reduce fuel cycle cost by increasing total average burn-up. As actual measurements, large diameter fuel pins are applied to increase the internal conversion, the amount of blankets is reduced as much as possible. The main results are summarized as follows:(1) Large scale reactor (Power 1,500 MWe)The cores to satisfy requirements and targets of FS could be constructed in Compact type and HIC type. Both types of core are found to enable to attain over 1.1 of breeding ratio at initial deployment of FBR with radial blankets and 1.04 of breeding ratio at major share stage of FBR without radial blankets under 150 GWd/t of core average burn-up.The total average burn-ups of HIS type core are 91 GWd/t at initial deployment and 110 GWd/t at major share stage. The fuel cycle cost reduces by 20~40 % in comparison to Compact type core. On the other hand, HIC type core becomes large in core diameter and increases the plant construction cost. However, that effect is very benign, unit cost of electricity generation that takes account of fuel cycle cost and plant construction cost is found to decrease. HIC type is recognized to be superior to Compact type in economics.(2) Medium scale reactor (Power 750 MWe)The cores to satisfy requirements and targets of FS could be constructed in Compact type and HIC type. The tendencies of both cores' characteristics are same as those in the larger scale reactor, and the decrease of unit cost of electricity generation is found to be larger than that in the large scale reactor.