Conceptual design of Innovative Water Reactor for Flexible Fuel Cycle (FLWR)

Okubo, Tsutomu; Uchikawa, Sadao; Nakano, Yoshihiro ; Akie, Hiroshi  ; Kobayashi, Noboru; Fukaya, Yuji   

For the future sustainable energy supply based on the matured LWR technologies, a concept of FLWR has been studied in JAEA. The concept utilizes the tight-lattice core loaded with the MOX fuel, and consists of two steps. The first step realizes a high conversion type one (HC-FLWR) to keep the smooth technical continuity from the LWR technologies. The second is the RMWR concept, which realizes a high conversion ratio over 1.0 for Pu multiple recycling. The key point is that the two core concepts utilize the same size fuel assemblies, and hence, the former can proceed to the latter in the same reactor system based flexibly on the future fuel cycle circumstances. In the present paper, investigation results on the FLWR conceptual design are presented. The design of the HC-FLWR core has been recently improved, and detailed core properties have been evaluated by the neutronics and thermal-hydraulics coupled calculations. The core can achieve the average burn-up around 55GWd/t.