ABSTRACTThe production of nuclear energy as well as the application of other nuclear technologies produces large volumes of low- and intermediate-level radioactive wastes. In many countries, these wastes are sorted and treated separately in well-developed treatment schemes. Plasma treatment, in particular, with microwave-driven plasma torches promises many advantages. To explore the feasibility of that technology, plasma treatment with a plasma torch controlled by a 2.45-GHz microwave signal of up to 200 W was investigated in previous work. It could be shown that all materials can be successfully treated, that is, combusted or melted in an open laboratory setup. Here, design and construction of a plasma oven with controlled material and gas flow with the surrounding are reported. In exploratory experiments, it was found that the efficiency can be increased by utilizing a rotating crucible which is hit by the plasma zone at an angle of 40°. In addition, it was shown that shredding the material to 2–3 mm was advantageous. Further milling did not improve the results significantly. These results were transferred to the oven design. A further increase in treatment efficiency of up to ∼45% has been found when performing the plasma treatment in the oven. The formation of NOx, a toxic component of the flue gas, was systematically investigated. The flue gas concentrations are high above legal limits during combustion so flue gas scrubbing is required. The basic design goals of the plasma oven were met and further investigations can be undertaken to investigate more details of plasma processing of radioactive waste.