Fate and transport of radiocesium, radiostrontium and radiocobalt on urban building materials

Kinetics of 137Cs, 60Co and 85Sr sorption on powdered building materials in aqueous suspensions at 20 °C for interaction times of 1, 7, 14 and 28 days were studied. The 137Cs distribution coefficient (Kd) values for all building materials except limestone practically did not change during 28 days of sorption. The Kd (85Sr) was several orders of magnitude lower than for 60Co. The highest values were observed for asphalt and granite. An effective method to study the radionuclide distribution in depth of building materials using layer-by-layer sanding was developed. Using the developed method, the 137Cs, 60Co and 85Sr distribution with depth of selected building materials at different air humidity, time and temperature was studied. Relative humidity (RH) was found to influence significantly the 85Sr depth distribution in the case of granite (unlike 137Cs and 60Co). While 85Sr penetrated to 0.5 mm in depth of granite at RH 30%, at RH 87% the depth of 85Sr penetration to granite reached up to 7 mm.