Main Results of a Remediation of Uranium- and CHC-Contaminated Groundwater

Since July 2002 a pump & treat remedial action has been in operation for the extraction of Uranium- and “CHC-compounds” contaminated water flowing in the ground of a formerly used industrial site where nuclear fuel elements were produced. Meanwhile about 21 kg Uranium and 28 kg CHC-compounds have been eliminated. Two ground-water plumes have transported the dissolved Uranium down-stream to locations where two main remediation-wells were in use for most of the remediation-time. They showed characteristic kinetic differences with respect to their U-nuclide vector from the very beginning. A meanwhile additionally close-by set well influenced that observation so that the formerly used two wells were assimilated gradually due to their relatively downstream position. Almost 300,000 m³ ground-water of the overall 440,000 m³ have been pumped therefrom. The second area’s remediation started in-between not being affected by the first plume’s aquifer. This observed assimilation is the result of intensive ground-water blending when the two plumes’ waters penetrate in a specific area by flowing within preferred aquifer’s paths. The first plume’s water characterized by decreasing Uranium-235 ratios is meanwhile dominated by the second plume’s water of up to 90% in case of the two elder wells. The overall activity of 132 MBq Uranium-235 has been extracted from the aquifer. Only a small area remains where the extraction of the first plume’s pure ground-water was started in 2009. The progress of the two plumes’ remediation is described by reporting the Uranium- and CHC-results of all wells. Nevertheless both target values of 20 μg/l and 10 μg/1 for dissolved Uranium and CHC-compounds, respectively, could not yet be reached for all remediation wells. In accordance to the 10μSv-concept of radiation protection the activity parameters have to be improved still in order to release the complete site from the German Atomic Law.