液态锂铅合金残渣中微量氚的回收

On the more efficient trace tritium recovery from the residue of liquid Li-Pb alloy

氚提取的系统设计中,如何严格限制氚损失和减小其辐射风险是非常重要的问题。利用同位素交换法对模拟液态锂铅合金残渣中的微量氚进行回收。研究结果表明,同位素交换法对液态锂铅合金残渣中的氚回收是有效的;交换载带气的最佳组成为He+0.1%D2。载带气相同时,交换温度和交换次数对渣中氚的回收率有显著影响。温度越高、交换次数越多,氚回收率越高;823K时,经过6次交换后的氚回收率接近80%。此外,依据气体与液态金属接触的动力学数学模型,推导出了锂铅合金滞留氚量释放的数学近似表达式。

The present paper is aimed at introducing our study on how to reduce the loss of tritium effectively and to minimize the radioactive exposure, in the process of trace tritium recovery from the residue of liquid Li-Pb alloy. For this purpose, we have investigated the isotope exchange process for the trace recovery from the imitative residue of the alloy. Our study results indicate that the isotope exchange system we have developed is an effective way for such recovery practices with the best component of exchange carrier gas being He ＋ 0.1% D2 and the optimal exchange temperatures and excfiange data being the main influential factors to the recovery efficiency. As the actual process shows, the trace tritium recovery efficiency is likely to increase with the rising of the exchange temperature and exchange amount. The highest tritium recovery efficiency can be made to reach 80% with the residue treated at 6 times at 823 K. In addition, we have also worked out a dynamic mathematical model for liquid metal recovery in the medium of gaseous atmosphere and the approximate mathematical equation of tritium residue in Li-Pb alloy on the basis of our experiments. Theoretical analysis of these data shows that the overall desorption process is likely to be governed by the diffusion of tritium atoms in the Li-Pb and by the heterogeneous reaction at the gas-eutectic interface of the tritium atoms recombination. Howeyer, for the time being, it remains impossible to deduce any kinetic parameters, such as the diffusion coefficient of tritium and the reaction rate of tritium on the alloy surface, for the tritium residence time involves a few other processes. Therefore, further investigations are needed to test the variables the amount and surface area of the sample may involve.