A Review of Possible Origins of the Uranium “Plume” in the Aquifer under the EPIC Site in the Chernobyl Exclusion Zone

The uniqueness of the Chernobyl accident lies in the fact that so much radioactive material was discharged to the atmosphere as solid fuel particles from the reactor core. Between the 26th of April and the 6th of May 1986 more than 6 tons of small particles of highly radioactive uranium oxide fuel were discharged to the atmosphere and were responsible for more than 75% of the radioactive contamination on the ground in the exclusion zone. In 1987, about 800 trenches had been dug in the exclusion zone to prevent re-suspension and to protect workers from contamination. In 1999, the IRSN, in collaboration with IGS and UIAR, equipped trench 22 (CPS) in order to monitor radionuclide migration in the environment (water, soil, plants). At the EPIC site high uranium concentrations were observed in the groundwater downstream from trench 22. We discuss the possible origins of this uranium “plume”.