Ruthenium: Nuclear's Volatile Problem

钌：核能的不稳定问题

• 批准号: 2504922
• 金额: --
• 依托单位: Lancaster University
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2504922
• 关键词: Ruthenium; Nuclear; Volatile; Problem

Ruthenium is a fission product possessed of two relatively long lived stable isotopes: Ru-103 (half life = 39.8 days) and Ru-106 (half life = 1 year). Both isotopes are present in UK spent fuel and so have had to be accounted for during the reprocessing or disposal of that fuel. At a number of stages during the processing of spent fuel, ruthenium can be exposed to high nitric acid, high temperature conditions that may lead to its transfer into the gas phase as ruthenium tetroxide. Two such stages are the dissolution of spent fuel into concentrated nitric acid at the start of reprocessing, and the vitrification of ruthenium into a glass waste form after reprocessing has occurred.Volatilisation is to be avoided as the resultant gas phase ruthenium may then redeposit within metal pipework elsewhere in the plant which will then have to be decontaminated. However, ruthenium volatilisation occurs at unexpectedly low temperatures. Whilst RuO2 is not seen to volatilise below 900oC, gaseous ruthenium oxides have been seen to evolve from solutions of Ru in nitric acid at temperatures as low as 150oC - making the management of ruthenium difficult during reprocessing and vitrification.Thus, given its volatile nature and high specific radioactivity ruthenium presents a strong challenge to the nuclear industry in effectively managing its abatement. Key challenges are to fully understand the highly complex solution/solid state chemistries that obtain not only under conditions relevant to dissolvers, evaporators and vitrification plants, but also in the decontamination methods used in its clean up. Using a combination of chemical, analytical and engineering approaches, we shall seek to address these challenges in this PhD. The specific objectives of the PhD will be to:1) Develop gravimetric, mass spectroscopic, electrochemical and spectroscopic analytical methods that will improve the understanding of ruthenium speciation in high nitric acid environments and oxidation state interconversion during oxidative / thermal treatment of same.2) Using these methods, to establish the kinetics of interconversion between ruthenium species, most especially Ru(III) to Ru(IV) and Ru(VIII) and Ru(IV) to Ru(VIII), and the resultant product distributions of these processes.3) To establish the influence that Ru(III) complexation may have on these interconversions and the role that RuO2 may have in supporting or inhibiting volatilisation.4) Establish the mechanism by which other fission product metal ions such as Ce(IV) may oxidise and thus potentially volatilise ruthenium.5) Investigate the role that key NOx species such as NO and HNO2 may have on oxidising Ru(III) directly or inhibiting the putative Ce(IV)-driven oxidation of Ru(III).

ruthenium是一种具有两个相对长的稳定同位素的裂变产物：RU-103（半寿命= 39.8天）和RU-106（半寿命= 1年）。这两种同位素都存在于英国用过的燃料，因此必须在重新处理或处置该燃料期间被考虑。在加工燃油的多个阶段，唯一可以暴露于高硝酸，高温条件可能导致其作为四氧化氟二氧化碳转移到气相中。这样的两个阶段是在重新加工开始时将用过的燃料溶解到浓缩的硝酸中，并且在重新加工发生后将氟化的玻璃化成玻璃废物形式。应避免使用量化，因为由此产生的气相ruthenium可能会在金属内红调在金属中。植物中其他地方的管道必须进行污染。然而，在意外的低温下发生了氟芬挥发。虽然没有看到RUO2在900oC以下挥发，但气态ruthenium氧化物已被认为是从硝酸在低至150oC的硝酸中的RU溶液中演变而来的 - 鉴于其在重新加工和玻璃化期间，难以管理芳族。高特异性放射性义族在有效管理其减排方面对核工业提出了巨大的挑战。主要挑战是完全了解高度复杂的解决方案/固态化学分配，这些化学不仅在与溶解度，蒸发剂和玻璃化植物相关的条件下获得，还可以在清理中使用的净化方法。使用化学，分析和工程方法的结合，我们将寻求解决该博士学位的这些挑战。博士学位的具体目标将是：1）发展重量，质谱，电化学和光谱分析方法，将改善高硝酸环境中对钌种种形成的理解，以及在氧化 /热处理期间的氧化态相互转化。2）使用这些方法，建立唯一物种（尤其是RU（III）到RU（IV）和RU（VIII）和RU（IV）到RU（VIII）的互连的动力学，以及这些过程的产物分布。 3）确定RU（III）络合物可能对这些互换具有的影响以及RUO2在支撑或抑制挥发时可能具有的作用。4）建立了其他裂变产物金属离子（例如CE（IV））可以氧化的机制。 5）研究了关键NOX物种（例如NO和HNO2）可能直接具有氧化RU（III）或抑制假定CE（IV）驱动的RU（III）的氧化作用。