Bias Voltage Effects on the Removal of Co and Mo by SF6/O2 Plasma for Radioactive Waste Decontamination

The equipments and components used in nuclear power plant such as piping and valves usually are contaminated by TRU elements and radioactive corrosion and fission products. In this experiment, the principle contaminants Co of corrosion product and Mo of fission product are examined by SF6/O2 plasma. To enhance the reaction rate, DC bias voltage is applied on the specimens. Experimental results demonstrate the applicability and effectiveness of plasma decontamination processing. Results show that the reaction rate of molybdenum is 10.21 um/min. at 290 .deg. C. In the case of cobalt, etching reaction hardly takes place at low temperatures. However, it begins to increase as temperature exceeds 350 .deg. C. The reaction rate is 2.56 um/min. at 420 .deg. C. Ion-assisted experiments are under conduction. To support these results OES, SEM, and AES analysis are followed