Design of small reduced-moderation water reactors

The reduced-moderation water reactor (RMWR) has been developed aiming at effective utilization of uranium resource, multiple recycling of plutonium and high burn-up and long operation cycle as one of the innovative nuclear systems. Under the collaboration of industry, academia and national institute, design of small RMWR has been carried out based on natural circulated core cooling with passive safe and simple components. Obtained reactor specifications are electric power of 330 MWe, breeding ratio of 1.01, negative void coefficient and core burnup of 65 GWd/t with 25 months continuous operation periods. Capital costs per unit power of the first small RMWR is estimated to be 35% higher than ABWR and expected to be largely reduced to the level of large plants with more successive construction of standardized units. (T. Tanaka)