The progress of considerations of cask decommissioning technology in Japan.

As the nuclear fuel cycle is fulfilled, the necessity has arisen of advancing technological development and standardization for implementing measures to decommission (disassemble, dispose of, etc.) used transport casks for spent fuel which have exceeded their service life.It is important to identify the requirements necessary for development of reasonable measures for disassembling and disposing of used casks, and to get a projection for disassembling and disposing of the used casks. Therefore, we gathered existing knowledge and information on caskdecommissioning technology. This paper describes the progress made in examining cask decommissioning technology in order to support future work.Specifically, we investigated contamination of casks, which have been used in Japan, with radioactive materials, assessed activation of casks prior to disposal, and report on the results of classifying the generated waste material, amount of material, and other elements into specific categories.