Leaching of Radionuclides from a Cement Composite Incorporating Evaporator Concentrates Generated at a Pressurized Water Reactor Nuclear Power Plant

Composite Absorbers Consisting of Inorganic Ion-Exchangers and Polyacrylonitrile Binding Matrix: Leaching of 137Cs from Cemented NiFC-PAN Absorber

“…Comparison of the "steady state" diffusion coefficients with similar values found in other studies [9] shows that the values calculated from our results are at least by one order of magnitude lower. This result is in good agreement with the above discussed very low cumulative fraction of caesium leached.…”

“…This finding is rather surprising since the literature data [9] usually state the main rate-determining leaching mechanism to be diffusion.…”

“…Except for the procedure recommended by IAEA [7], the most widely recognized method is the procedure described in ISO international standard procedure [8], From the point of view of its behaviour in cement matrix, caesium belongs among the elements that are not subject to hydrolysis in unhardened cement (of pH ~12). Such elements generally exhibit the highest leachability [9]. Caesium leachability is usually especially high when highly saline solutions (e. g. evaporator concentrates) are directly cemented and can reach up to 90% of the original total activity during the first week [10].…”

“…Caesium leachability is usually especially high when highly saline solutions (e. g. evaporator concentrates) are directly cemented and can reach up to 90% of the original total activity during the first week [10]. Admixtures of zeolites or bentonites into the grout were found to reduce the leaching significantly [9,11].…”

Geochemical factors affecting radionuclide transport through near and far fields at a Low-Level Waste Disposal Site

“…It is often found that actual leach data indicate a much faster release in the early time periods of the leach test and later satisfy the linear dependence of square root of the time parameter. Matsuzuru and Moriyama (1982), Godbee et al (1980), Matsuzuru and Ito (1978), and Dayal et al(1983) discuss cement waste form leach experiments that show a simiiar initial rapid release.…”