Decontamination process using CF4-O-2 microwave discharge plasma at atmospheric pressure

Application to decontamination is proposed of microwave discharge plasma in carbon tetrafluoride and oxygen mixture at atmospheric pressure. Prelimina ry cold experiments were conducted using cobalt oxide deposited on stainles s steel plate. Fluorine atoms proved to be generated in high concentration in the plasma, which fluorinated the deposited metal oxide into volatile ga seous form. Upon plasma irradiation during about 200s, the cobalt oxide dep osit was removed to 100% from plate surface. Thermodynamic equilibrium calc ulations on CF4-O-2 systems containing cobalt served to elucidate the mecha nism of metal oxide removal by microwave discharge plasma, and similar calc ulations on systems containing actinides (U, Pu etc.) and lanthanides (La, Gd etc.) indicated that the process should be applicable also to the remova l of these radioactive elements. It is concluded from the experimental and calculated results that decontamination is basically feasible with the prop osed method of using microwave discharge plasma in a CF4-O-2 system at atmo spheric pressure.