Migration behavior of particulate radioactive cesium species generated at ground surface

Tanaka, Tadao 

It is necessary to confirm that there is no significant radioactivity remaining on NPP site, for the site release beforehand. Cesium 137 (Cs) is the typical radionuclide caused from NPP. In this research, generation of particulate Cs species at ground surface and its migration behavior were examined. Migration experiments were carried out by a column method, in which deionized water was fed intermittently at the drying interval for 7 days into a sand layer contaminated with Cs. A portion of the Cs in the upper surface region, which formed particulate species by sorbing on fine particles, migrated into the deeper layer. Fine particle itself also was generated at the sand surface by weathering. The sand was weathered during the drying period, so that small amount of fine particles including Cs was newly dissociated from the sand. Such particulate Cs species may be accumulated slowly by repeated cycles of rainfall and drying, during long term.