Neutronic study of SCR core for under-sea scientific research vessel

Odano, Naoteru; Ishida, Toshihisa; Wada, Koji*; Imai, Hiroshi*

A very small reactor, SCR (Submersible Compact Reactor), whose thermal output is 1250 kW, is an integral-pressurized type reactor to be used as a power source for a scientific research vessel in medium depth region of the Arctic Ocean. Neutronic study has been carried out for design of the SCR core of which could achieve continuous long-term operation without refueling for 10 years considering 50 % of load factor of the core. In the present study, arrangement of fuel rods, U enrichment of UO fuel rods and reflector materials were surveyed. The U enrichment has been determined to be 9.5 wt% to satisfy design criteria. In the present study Be metal was adopted as a reflector material. Reactor physics parameters including reactivity coefficients and power distributions were evaluated for the determined core specifications. Reactor physics parameters related to core safety were also confirmed and the evaluated parameters indicated that the determined core specifications in this study satisfied design conditions.