Recent development in nuclear ship reactor in Japan

JAERI is conducting a design study on advanced nuclear ship reactors. Concepts of two types of reactor have been formulated so far. One is the 100 MWt-power MRX for the use of a bigger merchant ship or an ice breaker, and the other is the 750 KWt-power DRX for the use of a deep sea research submersible. They are adopted new technologies such as the integral type reactor with in-vessel steam generators and control rod drive systems, the water-filled containment, and the passive decay heat removal system. These new systems enable to satisfy the essential requirements for the next generation ship reactors, i.e. compact, light, highly safe and easy operation. JAERI is also performing research and development works on the peculiar components to be used, the advanced automatic operation systems, the study of the thermal hydraulic phenomena for the safety analysis of new system, etc.. This paper summarizes the design study of the MRX and the DRX and the research and development activities being carried out in the JAERI