Effects of Neutron-Irradiation on Tensile Properties of 3.5%Ni Steel

In an aerated soil layer under natural condition, water that infiltrates into it flows discontinuously because of repeated cycles of rainfall and drying. Therefore, column tests, in which 2,000 mi of deionized water was fed into sandy soil layer dried for 3~90 days after it is contaminated by ⁶⁰Co, ⁸⁵Sr and ¹³⁷Cs aqueous solution, were carried out to examine influence of the drying period on migration behavior of those nuclides.

All the radionuclides showed both a steeply decreasing part corresponding to their cationic form and a gradually decreasing part corresponding to their particulate form in the concentration distribution curve along the soil column depth. In the vicinity of the top surface of soil layer, no influence of drying on ⁶⁰Co and ¹³⁷Cs concentrations was observed, but ^S5Sr moved a little into a deeper part from the top surface with longer drying period. Such moving tendency of ^8ESr was found to be connected with the Ca²⁺ concentration in the interstitial water. In the deeper soil layer, no influence of drying on ⁸⁵Sr concentration was observed, but the ⁶⁰Co and ¹³⁷Cs concentrations were increased with the drying period. This is considered to be caused from that each product of the movable ⁶⁰Co(OH)₂ and the ¹³¹Cs adsorbed on the fine particle increased with the rise of pH and the fine particle concentration, respectively, during the drying period. Thus, this study has suggested possible causes affecting on the radionuclide migration under discontinuous flow condition.