Dissolution behavior of (U,Zr)O-based simulated fuel debris in nitric acid

(U,Zr)Oをベースとする模擬燃料デブリの硝酸中での溶解挙動

池内 宏知  ; 石原 美穂; 矢野 公彦 ; 鍛治 直也; 中島 靖雄  ; 鷲谷 忠博 

Ikeuchi, Hirotomo; Ishihara, Miho; Yano, Kimihiko; Kaji, Naoya; Nakajima, Yasuo; Washiya, Tadahiro

To explore the possibility of dissolving fuel debris as a potential pre-treatment for waste treatment, dissolution tests of UZrO and (U,Pu)ZrO were carried out in 6 M HNO at 353 K. While the U and Zr indicated congruent leaching from the simulated debris with U-rich compositions, a preferential leaching of U was observed with Zr-rich compositions. Taking into account these different dissolution phenomena, the dissolution rate analysis was carried out using surface-area model to calculate the instantaneous dissolution rate (IDR). From these findings, dissolution with HNO is expected to be only applicable in U-rich compositions ( 0.3) if the dissolution in 6 M HNO at 353 K is assumed. Application of complexing acids such as mixture of HNO and HF should be considered to increase the dissolution rate of the phases with Zr-rich compositions.