Testing of new techniques in decommissioning of a fuel (U,TH) fabrication plant, especial consideration to free release measurement of low uranium activities

For the decommissioning of a fuel fabrication plant like NUKEM-A the identification of uranium isotopes and thorium in large residue masses and volumes with contents down to natural levels is an important task. A contamination map of NUKEM-A was prepared and compared with the natural contents of uranium isotopes and thorium in conventional building materials. A liquid scintillation equipment was tested for detection of low uranium activities. A computer program was created to calculate calibration factors allowing the measuring techniques to be judged mathematically as used by a barrel scanner combined with height resolution gamma spectrometry. (author)