Study on highly-efficient enrichment of tritium water by use of distillation column packed with hydrophilic adsorbent

氚废水将从未来聚变反应堆的氚燃料循环设施中排出，或目前从裂变反应堆的铀燃料后处理厂排出。当其浓度低于法律规定的浓度（60 Bq/cm ^3）时，可直接从设施中排出。当其高于法律的值时，必须用大量淡水稀释排水或必须在设施中富集/分离。稀释过程中的困难较少。然而，当其氚浓度远高于规定水平时，我们需要开发一种新的同位素分离系统，以在低于规定水平的情况下对氚废水排放进行净化，并分离出少量的高水平氚水。CANDU反应堆重水分离的H_2H_2O同位素交换法虽然可以应用于氚的富集，但氘的分离设备还不成熟，需要进一步研究。 ...更多信息 并且它们需要特殊且昂贵的Pt催化剂。此外，Pt催化剂性能由于将包含在聚变设施的废气中的CO而劣化。因此，该工艺需要预处理以减少某些污染物。本文提出了一种新的同位素分离方法，利用亲水性吸附剂提高传统精馏塔的性能。作为亲水性吸附剂的候选者，硅胶和沸石吸附剂在本研究中进行了比较实验。根据H_2O和HTO之间的蒸汽压差计算的原始同位素分离因子为1.028。结果发现，通过使用亲水性吸附剂，同位素分离因子提高到1.1至1.2，因此可以缩小氚富集和分离的规模。该硅胶柱在不同的流速范围内均具有较大的分离性能。另一方面，沸石柱（商品名Linde分子筛13 X）在非常小的蒸气流速下获得最大的同位素分离性能，但在较高流速下分离因子降低。这是因为HTO在气相中与吸附剂上的H_2O交换反应比较慢。因此，沸石柱的传输单元（NTP）的数量远小于硅胶柱。沸石柱被认为是有效的，特别是对于非常小的蒸气流速。实验测定了瞬态氚富集性能，发现采用转移单元数的平板模型数值计算与实验结果吻合较好。实验和数值计算结果在下一页列出的研究论文中介绍。目前科学研究的摘要在一份报告中作了总结。少

Tritium-waste water will be drained from facilities for a tritium fuel cycle of a future fusion reactor or is presently exhausted from uranium fuel reprocessing plant for a fission reactor. When its concentration is lower than the legally regulated one (60Bq/cm^3), it can be drained from the facilities as it is. When it is higher than the legal value, the drain water has to be diluted by a large amount of fresh water or has to be enriched/separated in the facilities. There is less difficulty in the dilution process. However, when its tritium concentration is much higher than the regulated level, we need to develop a new isotope separation system to decontaminate the tritium-waste water drain at a lower level than the regulated level and to separate a small amount of high-level tritium water. Although the H_2H_2O isotopic exchange method that was used for a heavy water separation of CANDU reactor can be applied to the tritium enrichment, the facilities for the deuterium separation are h … More uge, and they need a special and expensive Pt catalyst. In addition, the Pt catalyst performance is deteriorated by CO that will be included in the exhaust gas of fusion facilities. Therefore, the process needs pretreatment to reduce some pollutants. In the present study, a new isotope separation method to enhance the performance of a classical distillation column with use of hydrophilic adsorbents. As candidates for the hydrophilic adsorbent, silica-gel and zeolite adsorbents were comparatively experimented in the present study. The original isotope separation factor based on the difference in vapor pressure between H_2O and HTO is 1.028. It was found that the isotope separation factor was enhanced to 1.1 to 1.2 with the use of the hydrophilic adsorbent, and therefore it can downsize the scale of the tritium enrichment and separation. The silica-gel column attained the comparatively large separation performance in the various ranges of vapor flow rate. On the other hand, the zeolite column (commercial name Linde molecular sieve 13X) attained the largest isotope separation performance at very small vapor flow rate, but the separation factor decreased at higher flow rate. This is because the exchange reaction between HTO in the vapor phase and H_2O on the adsorbent is comparatively slow. Therefore, the number of transfer unit (NTP) of the zeolite column was much smaller than that of the silica-gel column. The zeolite column is considered to be effective especially for the very small vapor flow rate. The transient tritium enrichment performance was experimentally determined, and it was found that the numerical calculation based on the plate model that uses the number of transfer unit fitted the experimental ones. The experimental and numerical results were presented in the research papers listed in the next page. The abstract of the present scientific research is summarized in a report. Less