Remediation of uranium- and CHC-contaminated groundwater on a former nuclear fuel-element production site - 16244

Since July 2002 a pump and treat remedial action has been in operation for the extraction of Uranium- and 'CHC-compounds' contaminated ground-water flowing below an industrial area used before as production site for nuclear fuel elements. So far about 17 kg Uranium and 22 kg CHC-compounds have been eliminated. As described earlier [1] two ground-water plumes have transported the Uranium down-stream to locations where two main remediation wells are placed. They show characteristic differences with respect to their Uranium-nuclide vector. More than 220.000 m3 ground-water of the whole 350.000 m3 have been pumped therefrom. Preferred ground-water paths cause blending the two plumes' waters. The first plume's water characterized by decreasing Uranium-235 ratios is meanwhile dominated by the second plume's water of up to 85% in case of well W10. The overall activity of 122 MBq Uranium-235 has been extracted from the saturated zone with decreasing quantities. Only a small area remains where the first plume's pure ground water will be extracted in future. Both target values of 20 μg/l and 10 μg/l for dissolved Uranium and CHC-compounds, respectively, could not yet be reached for all remediation wells. In accordance to the 10 μSv-concept of radiation protection the improvement of specific parameters will still be necessary in order to release the complete site from the German Atomic Law. (authors)