放射性廃棄物地中処分の安全性の評価に関する研究 (I)

放射性陽イオンの交換吸着体への分配におよぼすCa²⁺の影響

抄録

The adsorption of radioactive cations to clay minerals, which governs the movement of radioactive cations through saturated zone, was investigated.
In this study we dealt with calcium ion as the only ion in ground water which influenced the adsorption of radioactive cations to clay minerals.
The experiments were carried out with seven radioactive cations (²²Na, ¹³⁷Cs, ⁵⁴Mn, ⁶⁰Co, ⁶⁵Zn, ⁸⁵Sr and ¹³³Ba) and three ion exchangers (Amberlite IR-120B, Green Sand and KUR Sand) in stead of clay minerals.
The distribution coefficient Kd_A of a radioactive cation to a saturated ion exchanger with calcium ion, was investigated experimentally under several concentrations of calcium ion (C_Ca).
On the basis of experimental results, the following empirical equation obtained.
Kd_A=m·(C_Ca)^-n
In this equation, the values of m and n are determined mainly by the type of radioactive cations and ion exchangers.