In situ decontamination of KRB primary circuit components

In 1977 and 1978, decontamination work had to be carried out in some areas of the steam generators and their piping of the 250 MWe boiling water reactor of the Gundremmingen Nuclear Power Station (KRB). Little experience on a technical scale has so far been available about the decontamination of primary circuit components. This is particularly true of unassembled components of the type described here. Decontamination, which was carried out as a radiation protection measure prior to repair work, was performed after more than ten years of plant operation. After eight months of outage dose rates between 500 and 1000 mr/h were measured in areas in which welding work had to be carried out. At one other point, to which a remotely controlled manipulator had to be moved for repair purposes, the dose rate was between 5 and 15 r/h. Both mechanical and chemical decontamination techniques were possible. These activities also required the provision of supply and measuring systems. (orig.)