Colloquium: Ian Bourg

Ian Bourg, Assistant Professor, Department of Civil and Environmental Engineering, Princeton University

Abstract - Two radioisotopes of cesium, ¹³⁵Cs and ¹³⁷Cs, are among the most important contaminants associated with the nuclear fuel cycle. In particular, ¹³⁷Cs released during the Fukushima nuclear disaster on March 11, 2011 is the main source of external radiation dose in a region covering roughly 3 to 8 % of the land area of Japan. The predominant process controlling the solubility and mobility of cesium in soils and sedimentary environments is the formation of strong surface complexes with clay minerals, and particularly with micaceous minerals (illite, vermiculite, mica).  Experimental data indicate that illite, in particular, carries a small density of surface sites with a very high affinity for cesium, but the detailed properties of these sites remain poorly understood.  Here, we present new molecular dynamics (MD) simulation results on the adsorption of cesium on illite and mica.  Our results provide new insights into the structure and stability of surface complexes formed by cesium on micaceous minerals.