Active demonstration of the thermal treatment of surrogate sludge and surrogate drums using the GeoMelt™ In Container Vitrification (ICV) melter installed in NNL Central Laboratory

Abstract

Under the auspices of the THERAMIN project, the GeoMelt™ in-container vitrification (ICV) melter system installed in the National Nuclear Laboratory (NNL) Central Laboratory at Sellafield, UK, has been used to demonstrate the immobilisation of two surrogate feeds. The streams selected for demonstration were a cementitious stream representative of legacy drums or failing cemented wastes packages and a wet waste stream made up of a surrogate for Magnox storage pond sludge and clinoptilolite, an ion exchange material, as a way of demonstrating co-immobilisation. The distribution of waste species throughout the vitrified block were assessed to determine the efficacy of the mixing during the thermal treatment process. Analysis of samples from the off-gas system was carried out to establish an activity balance across the process. This paper will outline the process set up, provide operational data from the melt concluding with an assessment of the applicability of the trials results to thermal treatment of these and similar waste streams.