トリチウムガスの酸化に及ぼす紫外線の影響 : 酸素圧及び水素圧依存性

概要

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It has been reported in the previous paper that UV-Photon irradiation significantly enhances the oxidation of tritium gas (HT) in an oxygen atmosphere. To understand the mechanisms of this effect, we studied the pressure dependence of this reaction. The oxidation rate was determined by measuring the amount of tritiated water formed as a function of irradiation time by use of a conventional liquid scintillation counter. It was found that the oxidation rate increased linearly with oxygen pressure in the range 0～160 Torr under a constant hydrogen pressure of 0.7 Torr: namely, the reaction obeys the first order kinetics with respect to oxygen. This indicates that excited oxygen atoms, O(3P), formed with UV-photon irradiation play an important role for the enhancement of the oxidation. Hydrogen pressure dependence was examined with varying hydrogen pressure in the range from 0～5.5 Torr under a constant pressure of 160 Torr. In this case, the amount of tritium used was kept constant. It was observed that the formation rate of tritiated water decreased with the increase in hydrogen pressure: the rate was approximately proportional to {[HT]/[H2]}1/2. Based on those observations, plausible mechanisms of the photon-induced oxidation of tritium gas in an oxygen atmosphere are discussed along with need for further systematic studied.
富山大学の論文