地層中移行試験に用いる放射性核種供給源構成素材の核種吸着・脱離特性

抄録

In order to select an available inlet source material for a migration test of radionuclides in a sedimentary layer, 8 different materials; carbonated cement, coastal sand, chromosorb, sandstone, cation-exchange resin, zeolite, silica gel and Toyoura standard sand, were tested in terms of adsorption ability and leaching rate with time for ⁶⁰Co, ⁸⁵Sr and ¹³⁷Cs. The adsorption terms of adsorption ability and leaching rate with time for 60Co, 85Sr and 137Cs. The adsorption abilities obtained as distribution coefficients (Kds) were tested by batch-type experiments, and the leaching rates were examined using column-type experiments.
Among the materials, silica gel had the smallest Kd of approximately 60ml/g for the three radionuclides, and its Kd values did not fluctuate with time. Cement, sandstone and silica gel had a constant leaching rate for ⁶⁰Co, ⁸⁵Sr and ¹³⁷Cs, ranging from 50 to 300ml inflow of groundwater. Approximately 70% of the three radionuclides were leached out from silica gel by 500ml inflow of groundwater. These results suggest that the silica gel is a suitable inlet source material for constantly supplying a solution with various radioactivities into a geologic layer.