2022 年 130 巻 8 号 p. 731-734
In the present study, simultaneous gross immobilization of radioactive Cs and Sr in zirconium phosphate was investigated by two methods. In the “dry method,” a mixture of HZr2(PO4)3 with varying amounts of CsNO3 and Sr(NO3)2 was heat-treated at 700 °C for 5 h to prepare Cs + Sr immobilized samples. At Cs + Sr immobilization of 0.3 + 0.15, the leaching amounts of Cs and Sr in 1 mol·dm−3 of HCl solution treated at 160 °C for 24 h were 2.9 × 10−4 g·m−2 and 3.9 × 10−4 g·m−2, respectively. In the “autoclave method,” aqueous solutions containing 0.5 and 0.25 mol of CsNO3 and Sr(NO3)2, respectively, against 1 mol of (H3O)Zr2(PO4)3 were thermal-treated at 150–250 °C for 24 h to prepare Cs + Sr immobilized samples; immobilization of Cs and Sr was observed at 150 °C. The immobilized amount of Cs and Sr increased as the treated temperature increased, while the leaching amounts of Cs and Sr in 1 mol·dm−3 of HCl solution treated at 160 °C for 24 h decreased. The amount of immobilized Cs and Sr on (H3O)Zr2(PO4)3 at 250 °C were 0.30 and 0.20, and leaching amounts of Cs and Sr were 1.0 × 10−3 g·m−2 and 1.4 × 10−3 g·m−2, respectively.
