Optical emission spectroscopy diagnostics of oxygen plasma reaction of the accelerated oxidation of uranium dioxide

In this study, UO2 specimens are oxidated by O2/Ar plasma reaction. O2/Ar, O2/N2, and O2/He plasmas are diagnosed by OES. Experimental results shows that oxidation of UO2 is enhanced about 70-300% in oxygen plasma reaction than gas reaction. First, oxidation of UO2 in oxygen plasma at 400 .deg. C is accelerated about three times compared to that in oxygen gas at the same temperature and it is found that the reaction rate increases linearly with reaction time, which is in good agreement with earlier works. Experimental finding that higher plasma power brings to higher oxidation rate suggests that to acceleration may be ascribed to the increased oxygen radical which is produced by plasma reaction. At 500 .deg. C the reaction is also accelerated about 70%, However, it is not as high as than at 400 .deg. C. It seems that rate of UO2 oxidation in oxygen gas at 500 .deg. C is sufficiently high. It is confirmed by OES diagnostics that the number of Oxygen radical is increased by adding Ar, He,N2 gas on the O2 gas