Applicability of subcritical water treatment for degradation of spent tannin-based uranium adsorbent; Fundamental research

岩本 敏広 ; 大森 康平; 荒井 陽一 ; 船越 智雅; 渡部 創  ; 中村 雅弘 ; 渡邉 賢*

Iwamoto, Toshihiro; Omori, Kohei; Arai, Yoichi; Funakoshi, Tomomasa; Watanabe, So; Nakamura, Masahiro; Watanabe, Masaru*

TANNIX loaded with uranium and nitric acid ions has accumulated as a secondary waste of radioactive water decontamination. Establishment of treatment procedure of the spent TANNIX is an important issue for facility management. In this study, applicability of the subcritical water treatment for the spent TANNIX decomposition was experimentally examined. As the results, temperature conditions contributed significantly to the decomposition efficiency, and the solid-liquid ratio had a limited effect. The decomposition rate tends to decrease as the test time increases, suggesting that decomposition preferentially occurs around at functional groups. These experimental results showed that most of the TANNIX could be decomposed at high temperatures and longer reaction times. This study demonstrated that hydrothermal reactions can be used both to recover uranium from TANNIX and to decompose it.