Decommissioning of back-end nuclear facilities

Concerning the decommissioning of facilities related to reprocessing of spent nuclear fuel and processing and disposal of radioactive waste, i. e., facilities for waste conditioning or storage, specific features prevail. Such facilities are generally optimised for the handling of radioactive substances and, therefore, are frequently highly contaminated, but do not contain any activated material. One main concern of their decommissioning will usually be the decontamination of extended surfaces of process equipment and building structures. Depending on the extent and success of the decontamination, dismantling tasks might have to be remotely performed. Based on a survey of the number of such facilities, typical issues associated with their decommissioning were found to be well presented by focussing on the examples of the decommissioning of the two prototype spent fuel reprocessing plants at Dessel/Belgium and Karlsruhe/Germany. Such issues are mainly associated with the presence of alpha-contamination of the process equipment and large building structures. Experience gained from solving associated problems is discussed. (orig.)