NEW CONSTRUCTION OF “KAIEI-MARU” FOR THE TRANSPORT OF NUCLEAR FUEL MATERIALS

The Nuclear Fuel Transport Co., Ltd. (NFT) has been safely transporting radioactive materials by 3 exclusive ships for LLW and SF transport. The oldest ship Hinoura Maru, however, retired in 2005 after 30 years of service and the NFT was required to build a replacement transport ship for the Japan Atomic Energy Agency (JAEA) Fugen SF after 2006. The NFT ordered a new exclusive ship from the Mitsui Engineering & Shipbuilding Co., Ltd. and on September 7th, 2005, construction of the new ship began in the Tamano Works. On February 2nd of the following year, she was christened “Kaiei Maru” during the launching ceremony, and was completed on August 31st . Kaiei Maru has the following features that make it distinct from conventional ships: - Her safety equipment is updated and she is equipped with various devices for emergencies and physical protection. - MCNP was used for as the shielding calculation code. This is the first time in Japan that MCNP codes were utilized for the licensing of radioactive material transportation. This utilization eventually led to the reduction of weight of shielding concrete by more than 100 tons when compared to DOT code calculation. - Collision analysis was carried out by the FEM code to calculate the risk in the event of a collision between a VLCC and Kaiei Maru. The result of the analysis has proved that the loaded cask and the longitudinal bulkhead do not come into contact, even if a 15kt VLCC were to hit the center of her hull.