Measurements of Distribution Coefficient for U and Th on Sand Stone in Synthesized Sea Water and Distilled Water

Nakazawa, Toshiyuki*; Okada, Kenichi*; Yoshihiko, Saito,; Suyama, Tadahiro*; Shibata, Masahiro ; Sasamoto, Hiroshi   

Japan Nuclear Cycle Development Institute (JNC) has developed the sorption database for dentonite and rocks in order to assess the retardation capacities of important radioactive elements in natural and engineered barriers in the H12 report. However, there are not enough distribution coefficient data for radioactive elements in saline type groundwater in the database. Thus the batch sorption tests were performed for uranium(U) and thorium(Th) in saline type groundwater. For these elements, there are little registration numbers in the JNC's sorption database, and also these elements are important to evaluate the safety of disposal system. The experiments for each radioactive element were performed on the following conditions; *U:Kd measurements using the solutions (synthesized sea water and distilled water) reacted with sand stone as a function of carbonate concentration, under reducing conditions. *Th:Kd measurements using the solutions (synthesized sea water and distilled water) reacted with sand stone.