Strontium-90 migration to the geo-sphere from a waste burial in the Chernobyl exclusion zone
L. Dewiere, D.A. Bugai, C. Grenier V.A. Kashparov and N. Ahamdach
Journal of environmental Radioactivity, 74, 139-150
Results are presented from an ongoing field scale experimental study (namelyy the Chernobyl pilot site project) of processes controlling 90Sr releases from a shallow trench containing nuclear fuel particles and subsequent radionuclide transport in the underlying sandy aquifer at Chernobyl Nuclear power plant Site. Microscopic analyses of waste particles ans leaching experiments have shown that 10-30% of the radioactive inventory is associated with chemically extra-stable Zr-U-0 particles. The largest fraction of 90-Sr activity in the trench (= 30-60%) is currently associated with relatively slowly dissolving non-oxidized UO2 fuel particles. The 90Sr migration velocity in the eolian sand aquifer is retarded by sorption to =9% of groundwater flow velocity (Kd=2ml/g). The dispersity values for non-reactive solute transport in the aquifer predicted by geostatistics (i.e. 1.86 cm) were confirmed by a natural gradient tracer test usign 36Cl. The observed negative correlation between hydraulic consuctivity and Kd of aquifer sediments suggests thes 90Sr could be subjected to larger dispersion in the subsurface compared to 36Cl.