Experimental values for 241Am and 239+240Pu Kdʹs in French agricultural soils

Experiments resulted in determination of Kd values for 241Am and 239+240Pu in 6 soils whose characteristics are representative of agricultural soils found around French nuclear power plant sites. These experiments were conducted in stirred batch reactors and the sorption isotherms were plotted. For americium, the experimental Kd values varied from 60 to 4000 L kg−1 (d.w.) and correlated well with soil pH, Kd increased with increasing pH. As regards plutonium, the experimental Kd values varied between 300 and 9600 L kg−1 and decreased with increasing total sand content. The estimation of the total residence time determined by using a particular and experimentally refined value for Kd—with a model similar to those currently used for impact assessments—illustrates the importance of establishing values that are better suited to specific soils than generic values. Lastly, depending on the type of evaluation envisioned, it might be important to look for a specific value of Kd—and even modelling—more suited to the specificity of the scenario studied, by performing more complex, or even in situ, experiments.