铀吸氘和氚的动力学同位素效应

Kinetic Isotope Effects of Deuterium and Tritium Absorption by Uranium

应用反应速率分析方法,在高真空金属系统中测定了金属铀在恒容体系和150～300℃范围内吸收氘和氚的p-t曲线。由p-t曲线可知,在同一温度下,铀吸氚的速率与铀吸氘的速率基本相同;而随着温度的升高,由于解吸逆反应的影响,铀吸氚(氘)的反应速率降低。根据p-t曲线计算了吸气反应在不同温度的速率常数,得到铀吸氘和氚的表观活化能分别为(-42.8±0.3)和(-43.2±1.2)kJ·mol-1。从活化能数据可以看出,铀吸氘和氚的反应动力学同位素效应不明显。

The p-t curves of deuterium and tritium absorption by uranium were investigated at 150-300 oC by the reaction rate analysis in a constant volume system.The results show that the rate of tritium absorption is equivalent to the rate of deuterium absorption at the same temperature.However,the rate of tritium（deuterium） absorption is decreased when the tritium（deuterium） absorption temperature is increased due to the effect of contrary reaction namely desorption of uranium tritide（deuteride）.The rate constants of deuterium and tritium absorption at different temperatures are determined and the activation energy value obtained by this analysis is（-42.8±0.3） and（-43.2±1.2） kJ？mol-1,respectively.Therefore,there are not remarkable kinetic isotope effects for deuterium and tritium absorption by uranium.