Basic study on radiolysis of potassium nickel ferrocyanide

Arai, Yoichi  ; Watanabe, So  ; Takahatake, Yoko  ; Nakamura, Masahiro  ; Nomura, Kazunori  ; Nakajima, Yasuo  

Potassium nickel ferrocyanide (KNiFC) is one of the most effective adsorbents for decontamination of Cs in the radioactive waste solutions. Although the ferrocyanides are known to be chemically stable, HCN and H gases are suspected to be generated by radiolysis. Generations of those gases should be suppressed or controlled in order to prevent hazards. In this study, ray irradiation experiment on KNiFC absorbing Cs was carried out to evaluate stability of used ferrocyanides. ray irradiation was performed using Co source, and the integrated dose was 0.13-6.0 MGy. After the irradiation, concentrations of H gas, of CN and of Cs were analyzed. G-value of H calculated from the concentration of H gas showed that generation of H gas prompted by adding KNiFC into water. And the Cs charge in the compound did not influenced on the G-value. Therefore, concentration of H gas in the tank for the used KNiFC has to be attenuated by ventilation. Although analyses on CN and Cs revealed that KNiFC is stable up to 3 MGy irradiation, small amounts of them were observed in the liquid phase after 6 MGy irradiation.