Observations on the geology and geohydrology of the Chernobyl' nuclear accident site, Ukraine

The most higly contaminated surface areas from cesium-137 fallout from the April 1986 accident at the Chernobyl' nuclear power station in Ukraine occur within the 30-km radius evacuation zone set up around the station, and an 80-km lobe extending to the west-southwest. Lower levels of contamination extend 300 km to the west of the power station. The deposition of this radioactive dust on the surface and the subsequent entombment of the damaged reactor effectively result in the de facto establishment of an above-ground nuclear waste storage site. This site is located on a thick sedimentary sequence of loose, mostly clastic deposits, with a shallow (generally 3-5 m) water table. The geology, the presence of surface water, a shallow water table, and leaky aquifers at depth make this an unfavorable environment for the long-term containment and storage of the radioactive debris. An understanding of the general geology and hydrology of the area is important to assess the environmental impact of this unintended waste storage site, and to evaluate the potential for radionuclide migration through the soil and rock and into subsurface aquifers and nearby rivers.