Study on release behavior of volatile ruthenium species with thermal decomposition of ruthenium(III) nitrosyl nitrate

Abe, Hitoshi ; Masaki, Tomoo; Watanabe, Koji; Tashiro, Shinsuke ; Yamane, Yuichi  ; Amano, Yuki ; Yoshida, Kazuo ; Uchiyama, Gunzo 

The release and transport characteristics of radioactive materials under the boiling and drying accident of the high active liquid waste (HALW) in a reprocessing plant have been studied. It has been reported that Ru, which is one of the important nuclides for evaluating public dose from the volatile viewpoint, is released mainly with progressing dryness of HALW. In this work, to grasp the release behavior of Ru, release ratio of Ru with thermal decomposition of Ru nitrate, which would be in the dried HALW, was measured and release rate constant of Ru from the nitrate was estimated. It was found that the calculation result of release rate of Ru from the nitrate with rise of temperature by using the constant could well simulate the result acquired from the beaker-scale experiment.