Submerged Water Jet Decontamination Of Multi-Element Bottles - 11521

UK nuclear fuel reprocessing is carried out at Sellafield. Fuel is stored in a variety of storage vessels according to fuel type and dimensions. Within the THORP reprocessing plant and its associated storage ponds, the most significant vessels are Multi Element Bottles (MEBs) used for storage and transfer of PWR and BWR fuels. A number of MEBs are now becoming redundant and occupy pond space. The construction of each MEB type differs in one or more of the following, numbers of compartments (5-18), compartment lengths, or dimensions of compartment. The MEBs are internally contaminated with fuel crud, high in cobalt-60 and generally associated with iron deposits from reactor operations. The crud ranges from loose, lightly bound to being entrained into metal surfaces. Radiometric analysis of the MEB population indicates over half the MEB fleet to be ILW. This prevents withdrawal from the pond unless within a flask or allowed to decay store. Contaminating crud was mobilised with a spinning water jetting system deployed on a bespoke deployment lance, with liquids and mobilised solids extracted and then captured using existing plant infrastructure. All wastes could then be disposed of via existing waste routes. Building on the success of the trials, the plant will be commissioning design works to incorporate the decontamination process alongside normal operations.