Realistic partition coefficients on radionuclide migration under near-surface condition

Sato, Kazuhiko ; Koga, Osamu; Tokizawa, Takayuki

For the purpose of safety analysis on reclamation of uranium mine and site release after decommissioning of uranium utilizing facilities at Ningyo-toge Environmental Engineering Center, realistic selection of partition coefficients from published data has been carried out based on groundwater chemistry. It is concluded as follows; (1) Values of selected partition coefficients on uranium, thorium, lead, polonium, protactinium and actinium were larger compare to conservative values applied for the preliminary study in the reclamation plan of uranium mine site at Ningyo-toge, whereas values on radium were smaller. (2) Radionuclide fluxes estimated for Yotsugi mill tailings site with those coefficients would be smaller than that of conservative settings due to potential existence of clay and iron-bearing minerals. However, (3) it is necessary to consider validation with certain real data and application of modeling such as surface complex model to make them more reliable.