Research and Development on C-14 Isotope Separation.

本文研究了碳同位素分离技术，以减少石墨反应堆退役时产生的碳-14污染废物。由于石墨最简单的处理方法是燃烧，因此选择CO和CO_2作为分离的工作材料。研究活动分为以下三个子主题。(1)用分子轨道理论研究碳同位素效应用高斯98 7A计算化学程序确定了CO与Cu (I)、Ag (I)离子配合物和CO_2与30种胺配合物的最适宜分子结构和分子振动。利用计算得到的振动频率，计算出各同位素分子的配分函数降阶比，从而计算出CO和CO_2配合物的分离因子（α）。(2) CO配合物碳同位素效应的实验研究CO可以与Ag (I)和Cu (I)离子形成配合物。本文测定了CO与Ag (I)配合物在非水溶剂和Cu (I)离子在水溶液和胺甲醇溶液中的同位素分离系数，测定了不同温度下CO与Ag (I)配合物的稳定同位素对^<12>C和^<13>C。在43℃时α的最大值为1.03。结果表明，对于^<12>C和^<14>C同位素对，可以预期α=1.06。(3)离子交换多级富集研究作为CO_2配合物体系同位素多级富集的基础研究，采用负离子交换树脂填充柱进行了Cu (I)和Fe （III）氯化配合物的色谱实验。在这些实验中，在Cu (I)和Fe（III）离子吸附带的边界处成功地观察到铜和铁的同位素分离。

The present work deals with the carbon isotope separation to reduce C-14 contaminated waste generated at the decommissioning of the graphite type reactors. Since the simplest treatment of the graphite is burning, CO and CO_2 were selected as the working materials for the separation. The research activities are divided into following three sub-topics.(1) Theoretical study on carbon isotope effects by molecular orbital theoryThe most appropriate molecular structures and molecular vibrations of CO complexes with Cu (I) and Ag (I) ions and CO_2 complexes with 30 amines were determined by using the computational chemistry program of Gaussian 98 7A.By using computed vibrational frequencies, the reduced partition function ratios of the isotopic molecules were calculated and thus the separation factors (α) of CO and CO_2 complexes were calculated.(2) Experimental study on carbon isotope effects of CO complexesCO is known to form complexes with Ag (I) and Cu (I) ions. In the present work the isotope separation coefficients of CO complexes with Ag (I) in non aqueous solvents and Cu (I) ions in aqueous solutions and amine methanol solutions were determined for the stable isotope pair of ^<12>C and ^<13>C at different temperatures. The maximum value of α observed was 1.03 at-43℃. The results suggest that one can expect the value α=1.06 for the isotope pair ^<12>C and ^<14>C.(3) Study on ion exchange multi-stage enrichmentAs a basic study on the multi-stage isotope enrichment of CO_2 complex systems, chromatographic experiments of Cu (I) and Fe (III) chloride complex were performed using column packed with anion exchange resin. In these experiments, the isotope separations of copper and iron were successfully observed at the boundaries of Cu (I) and Fe(III) ion adsorption bands.