Addressing self-irradiation damage and its impact on the long-term behaviour of nuclear waste matrices

核裂变提供了一种可靠的低碳能源，但核反应堆运行产生的核废料需要在耐用材料中进行适当处理和限制，以确保生物圈在近期和长期内不会受到放射性元素的污染。地质处置(GD)--将宿主材料限制在安全屏障(通常是金属罐)内，然后将这些废物永久堆积在预先选定的地质地点--现在是包括英国在内的国际公认的方法。尽管如此，几千年后，外部安全屏障会被腐蚀，宿主材料会暴露在周围的地质条件下。当与水/湿气接触时，放射性元素可能从宿主基质释放到周围的地质环境中，在那里它们可以被输送到生物圈。了解废物包装的长期变化--从制造之日起--是解决放射性同位素最终释放问题的关键因素。除了腐蚀，废物包装在地质处置条件下会发生变化的原因之一是受限放射性同位素的放射性衰变会在原子水平上破坏基质，称为自辐射损伤。这种几十万到几百万年的损害积累可能会改变废旧包装的化学和机械耐久性。这些辐射诱导的修饰可以对放射性同位素的最终释放产生重大影响。因此，解决废物包装的辐射稳定性是证明地质处置长期安全的重要组成部分。这项研究计划将利用哈德斯菲尔德大学的迈阿密辐射设施来研究从玻璃到玻璃陶瓷复合材料等各种类型的废物包装中自辐射损伤和He积累的影响。使用具有原位双离子束照射的透射电子显微镜，将实时监测辐照引起的修饰。双离子束辐照是核废料中最接近自辐照损害的一种，可产生可靠和现实的结果。这些离子辐照效应将与将与核工业合作伙伴合作进行的鳗系元素掺杂研究进行比较，从而能够确定模拟自辐照损害所需的辐照条件。这项研究将对浸出(凝胶)和未浸出的材料进行，以了解辐射诱导的废物包装的演变，并解决辐射损伤对浸出的影响，反之亦然。通过与澳大利亚ANSTO、法国CEA MarCoule、剑桥大学和英国国家核实验室等外部合作伙伴的合作，这项建议将汇集国际公认的研究人员的经验和专业知识，以更好地了解地质处置条件下(包括淋滤)自辐射破坏所造成的废物形态演变。

Nuclear fission offers a reliable low carbon source of energy, but, the nuclear waste generated as a result of nuclear reactor operation needs proper treatment and confinement in a durable material to ensure that the biosphere is not contaminated with radioactive elements in the near and long-term future. Geological disposal (GD) - which involves confining the host material inside a safety barrier (usually a metal canister) and then permanent deposition of such wastepackages in a pre-selected geological site - is now an internationally accepted methodology including the UK. Nonetheless, after thousands of years, the outer safety barrier will get corroded and the host material will be exposed to the surrounding geological conditions. When in contact with water/moisture, the radioelements may be released from the host matrix into the surrounding geology from where they can be transported into the biosphere. Understanding long-term changes in the wastepackages -starting from the day of their fabrication - is a key element in addressing the eventual release of the radioisotopes. Besides corrosion, one of the reasons why the wastepackages will change under geological disposal conditions is the fact that radioactive decay of the confined radioisotopes will damage the host matrix at atomic level called as self-irradiation damage. This damage accumulation over hundreds of thousands to millions of years can potentially alter the chemical and mechanical durability of the wastepackages. These irradiation induced modifications can have a significant effect on the eventual release of the radioisotopes. Thus, addressing radiation stability of the wastepackages is an essential part of demonstrating long-term safety of the geological disposal.This research proposal will utilize MIAMI irradiation facility at the University of Huddersfield to study the effects of self-irradiation damage and He accumulation in various types of waste packages ranging from glasses to glass-ceramic composites. Using a transmission electron microscope with in-situ dual-ion-beam irradiation, the irradiation induced modifications will be monitored in real time. The dual-ion-beam irradiation represents the closest analogue to self-irradiation damage in nuclear wasteforms yielding reliable and realistic results. These ion irradiation effects will be compared with actinide doping studies to be undertaken in collaboration with nuclear industry partners, thereby, allowing establishing the irradiation conditions necessary to simulate the self-irradiation damage. The research will be undertaken on leached (gels) and non-leached materials to understand the irradiation induced evolution of the wastepackages and address the effect of radiation damage on the leaching and vice versa. By collaborating with external partners such as ANSTO Australia, CEA Marcoule France, University of Cambridge and, National Nuclear Lab UK, this proposal will bring together the experience and expertise of internationally recognised researchers to develop a better understanding of the wasteform evolution due to self-irradiation damage under geological disposal conditions including leaching.