REMOTE HANDLING OPERATION TECHNIQUE FOR HIGH-LEVEL RADIOACTIVE WASTE REPOSITORY INVESTIGATION AND PERFORMANCE TEST FOR SEVERAL DIFFERENT EMPLACEMENT CONCEPTS

During the operation of repository of high-level radioactive waste, waste package and engineered barrier will be transported from aboveground facility to underground facility, then be emplaced at a certain place of the repository. From the view point of operation safety and radiation safety through this process, technical feasibility for a variety of options for remote handling and remote emplacement of the waste package and engineered barrier must be provided at this moment in our repository program in Japan. In this study, several EBS concepts, especially for different types of buffer material – block, monolith, insitu compaction, pellet, and pre-assemble (pre-fabrication) – were combined with two emplacement concepts –vertical and horizontal-. Then key technical issues of these different remote operation methods from aboveground facility to underground facility were classified into hard- and soft-ware element. According to the key technical issues, priority and methodology of investigation and performance test for remote handling and remote emplacement were settled. In this paper the following two concepts were mainly discussed. For the block type buffer material, forming method and condition were investigated. Through a thick/ near full-scaled bentonite block forming test, a relationship between compaction pressure and density distribution of bentonite was confirmed, and a scale effect of full scale block forming was discussed. A vacuum suction cup was applied to lift the formed block, and several lifting properties and condition were evaluated. Degradation phenomena of formed bentonite block were also investigated under exposure condition of high-temperature with high humidity air, and relation between water content ratio and degradation phenomena was discussed. For the pre-assembled EBS concept, an air pressure used mechanism was investigated the applicability and property to lift and to transport in the underground drift for the heavily assembled module.