The need to protect operators and to control the spread of contamination during Joint European Torus (JET) machine maintenance leads to the generation of soft housekeeping materials contaminated with tritium. These materials consist mostly of various plastics. A portion of the material falls into the category of intermediate-level waste and might need to be processed rather then disposed of as waste. This study deals with combustion in pure oxygen as a primary process for waste volume reduction. A mass reduction factor of 13 or greater has been demonstrated. The facility tested is of scale sufficient to meet the JET needs. The results of inactive experimental trials for the individual plastics and their mixtures are presented. The collection of chlorine-containing compounds released into the process gas during decomposition of polyvinylchloride and issues of complying with air pollution prevention regulations in the European Union have been addressed.