Treatment and decomposition of HLW-79Y-4T type transportation cask for liquid radioactive fuel material

The HLW-79Y-4T type transportation cask for liquid radioactive fuel material (commonly called 'Cendrillon') was imported from France and modified for Japanese regulation in order to obtain high-level radioactive liquid waste (HLW) for partitioning tests in JAERI by transportation from Tokai Establishment of Japan Nuclear Fuel Cycle Development Institute. The cask was used for the HLW transportation five times from 1982 to 1990. After that, it was kept and maintained for next transportation of HLW from facilities outside JAERI. Finally, we decided to decompose the cask because HLW can be obtained in JAERI Tokai. For the decomposition, radiation dose and contamination by radioactivity were first measured and then the methods to reduce those levels were determined. The cask was decomposed after the decontamination to separate the part that has high radiation level. The separated part was put in a vessel specially prepared. The present report describes those procedures for the decomposition of the transportation cask. (author)