Improving the safety and reliability of geological disposal of higher activity radioactive waste via geothermal energy co-production

根据核退役管理局的规定，高放射性废物（HAW）包括高放射性废物（HLW）、中放射性废物和一些不适合在低放射性废物处置库处置的低放射性废物。来自再处理的高放废物通常以液体形式存在，并在长期储存和处置之前通过称为“玻璃化”的过程转化为固体产品。储存是通过将罐放入空气冷却储存，直到合适的处置路线可用。一个设施将储存玻璃化的高放废物至少50年，然后再处置。英国政府对有害废弃物的长期管理政策是地质处置，即将废弃物深埋在地下的地质处置设施（GDF）中。GDF包括多个工程屏障，位于地下数百米处，建造在合适的地质环境中，以确保废物中的放射性被充分隔离和控制，从而在数十万年内不会对人类和环境造成危害。目前英国没有GDF运行，但政府目前正在制定选址程序，以找到一个地质条件合适的志愿者收容社区。威尔士政府还决定采取地质处置政策，对HAW进行长期管理，并继续支持自愿参与政策。苏格兰政府的政策是，高放废物的长期管理应该在靠近废物来源的可回收近地表设施中进行。这在设计GDF时提出了技术挑战，因为释放的热能可能对天然和工程屏障的物理和化学稳定性产生影响，对GDF的长期安全性和可靠性产生潜在影响。例如，如果岩石的原始结构被改变，它可能会改变地下水的运动模式和放射性核素向环境的运输路径。本项目旨在研究通过定制的闭环地热能回收系统控制GDF中的温度场的潜在好处，其中HAW将充当高温人为地热源。考虑到深度、布局、现场地质特征、放射性存量和预期温度场随时间的发展，将开发和评估潜在GDF应用的地热工程设计概念。将评估其对GDF长期完整性的影响，以及用于热和/或发电或用于维持稳定储存库条件的可回收能量的数量，同时考虑安全，操作和环境限制。该项目为高度积极的地球科学家，物理科学家或工程师提供了一个理想的机会，以开发影响能源和环境的重要问题的解决方案。该奖学金将受益于格拉斯哥大学科学与工程学院研究生院的博士培训机会。这项工作将在格拉斯哥的工程学院与位于东基尔布莱德的苏格兰大学环境研究中心合作进行。

According to the Nuclear Decommissioning Authority, Higher Activity Waste (HAW) includes HighLevel Waste (HLW), Intermediate Level Waste and some Low Level Waste that is unsuitable fordisposal in the Low Level Waste Repository. HLW from re-processing typically occurs in liquid formand is converted into a solid product via a process called 'vitrification' prior to long-term storage anddisposal. Storage is via canisters placed into an air-cooled store until a suitable disposal routebecomes available. A facility would store vitrified HLW for at least 50 years before disposal. The UKGovernment's policy for long-term management of HAW is geological disposal, which involvesplacing waste deep underground in a Geological Disposal Facility (GDF). A GDF includes multipleengineered barriers, several hundred metres underground, constructed in a suitable geologicalenvironment to ensure that the radioactivity in the waste is sufficiently isolated and contained thatit will not cause harm to people and the environment for many hundreds of thousands of years.There is currently no GDF operating in the UK, but the Government is currently developing a siteselection process to find a volunteer host community with suitable geology. The Welsh Governmenthas also decided to adopt a policy of geological disposal for the long-term management of HAW andcontinues to support the policy of voluntary engagement. Scottish Government policy is that thelong-term management of HAW should be in retrievable near-surface facilities close to the origin ofthe waste.The temperature of HLW can rise significantly because of its radioactivity. This poses technicalchallenges when designing a GDF, due to the impact that the released thermal energy could have onthe physical and chemical stability of both natural and engineered barriers, with potentialconsequences for the GDF's long-term safety and reliability. If the original structure of the rock isaltered, for example, it may change a groundwater movement pattern and the transport pathwayfor radionuclides to the environment. Also, waste glass could undergo devitrification.This project aims to investigate the potential benefits of controlling the temperature field in a GDFvia bespoke, closed-loop geothermal energy recovery systems, where the HAW would act as a hightemperature anthropogenic geothermal source. Geothermal engineering design concepts will bedeveloped and evaluated for potential GDF application taking account of depth, layout, geologicalcharacteristics at the site, the radioactivity inventory and the anticipated temperature fielddevelopment over time. Their impact on the long-term integrity of GDFs will be assessed, as will theamounts of recoverable energy for heat and/or power generation or for use to maintain stablerepository conditions, taking account of safety, operational and environmental constraints.The project provides an ideal opportunity for a highly motivated geoscientist, physical scientist, orengineer to develop solutions to important problems affecting energy and the environment. Thestudentship will benefit from the doctoral training opportunities of the Graduate School of thecollege of science and Engineering in Glasgow University. The work will be conducted in the Schoolof Engineering in Glasgow, in collaboration with the Scottish Universities Environmental ResearchCentre in East Kilbride.