Vitrification of high-level waste

Following decommissioning of the Karlsruhe Reprocessing Plant (WAK) in 1991, complete disposal has been planned by 2010 on the basis of the revised overall decommissioning, demolition and disposal concept. In the nearly twenty years of plant operation, reprocessing 208 t of spent nuclear fuel gave rise to a total of approx. 80 m3 of high-level waste concentrate (HLWS) currently stored in two shielded, cooled stainless steel tanks. Complete disposal of WAK requires the disposal also of this waste. Under the previous general concept, thirty HLWC shipments by rail were to be made to Mol, Belgium, and the waste was to be conditioned in the Mol Pilot Plant for the Production of Waste for Storage (Pamela). Between 1985 and the end of operations in 1991, some 900 m3 of high-level fission product solutions were processed in that plant, and 490 t of vitrified product was filled into some 2000 glass canisters. As shipments of high-level liquid waste to Belgium are now being considered more difficult, because of new developments and changed boundary conditions, and as the cost risk of such transports has also increased, in situ vitrification is now being proposed. This offers advantages arising from the absence of filling and shipping, but requires a new Karlsruhe Vitrification Plant (VEK) to be planned and built. In view of the comparatively small waste volume, a cost-effective plant is envisaged which is to be adapted to technical boundary conditions in a modern design concept. (orig.)