Composition of insoluble materials in highly active liquid waste at Tokai Reprocessing Plant

The elemental composition of insoluble materials in highly active liquid waste (HALW) at the Tokai Reprocessing Plant was analyzed. To evaluate the composition of insoluble materials between the treatment and storage processes, samples from the evaporator and two vessels which differ in the storage period, were taken. The amount of insoluble materials was evaluated on difference of weight of the filter before and after filtration. Inductively coupled plasma atomic emission spectrometry and isotope dilution mass spectrometry were used to determine the elements in samples dissolved by sulfate fusion. Zr and Mo were the main components of insoluble materials and small amounts of Rh, Ru and Pd were also found. Zr concentration of the filtrate was decreased as storage term, while Zr content in insoluble materials was increased. These results indicated that Zr compound could be re-precipitated in the HALW during the long term storage. (author)