UTGARD LAB PHASE II: A SIMFUEL FABRICATION & CHARACTERISATION FACILITY

英国目前约有16%的电力来自核裂变，这是我们低碳电力的重要组成部分。为了让这种情况继续下去，为了让我们的能源使用按计划去碳化，未来很长一段时间都需要新的核电站。英国作为核裂变先驱的历史留下了储存乏核燃料（SNF）的遗产，预计在国家先进气冷堆（AGR）机群和Sizewell轻水堆（LWR）的生命周期内，乏核燃料（SNF）将增长到6200 teU。如果按照目前的预计产能进行新建，将会产生约16000 teU的uo2基乏轻水堆燃料。根据各个核国家的政策，SNF要么被再处理，要么注定要在地质处置设施（GDFs）中处置。发展先进的、更安全的再处理循环或安全的湿/干储存、回收和随后交付给GDF，需要详细了解SNF在与这些活动相关的条件下的演变和行为。在英国，由于实际SNF产生的极高辐射场，除了由Sellafield或NNL运营的少数专门的“热室”外，其他所有研究都被禁止。这种获取必然受到资源限制，因此阻碍了SNF研究关键领域知识的进步。避免这个问题的一种方法是模拟SNF (SIMFUELs)，由特殊制备的UO2（耗尽）颗粒组成，这些颗粒具有与实际SNF相同的微观结构，并添加化学成分来模拟反应堆中形成的钚和裂变产物。广泛的SIMFUEL成分的现成可用性将加速和加强对SNF中不同相的相对作用的理解以及对关键燃料行为的机理理解。目前，SIMFUEL在英国的制造仅在NNL进行，这再次出现了访问问题。因此，该提案的愿景是建立一个SIMFUEL制造和表征的大学设施，这将是英国高等教育景观中独一无二的设施，通过向外部用户提供开放访问，将有助于推动和加速英国SNF研究。考虑到英国目前的agr和LWR所使用的燃料，以及在新建的LWR中使用的燃料，我们的重点将放在氧化物SIMFUELs上——尽管着眼于未来的燃料循环，这将包括MOX和基于tho2的燃料。因此，拟议的设施将启动、支持和实现以下主题的研究：主题1：开发新的先进烧结路线，用于制造具有孔隙、裂变产物负载和缺陷微结构的simfuel，以更好地模拟真实的SNF。主题2：研究这些先进的simfuel，以及使用传统陶瓷加工技术制备的simfuel，在与燃料循环后端相关的一系列条件下的行为，包括湿/干临时储存、地质处置和新的后处理路线。潜在的学术用户包括任何与SNF的基本物理、化学和材料特性有关的人，以及它的储存、回收和处置。这不仅包括以退役/处置为重点的EPSRC TRANSCEND联盟和beis资助的回收和废物管理国家核创新计划，还包括在这一领域工作的核CDT学生。在工业上，我们已经从RWM有限公司，NNL和Sellafield那里获得了兴趣，他们希望以比目前更灵活的方式委托制造样品。拥有这样一个国家设施不仅对英国用户来说是一个巨大的推动因素，而且对来自海外的裂变研究合作者来说也是一个巨大的推动因素，因为一些国际实验室报告说，要获得SIMFUEL样品非常困难，这些样品可以快速生产和交付，并且由正在进行的研究项目迭代通知一系列成分。

The UK currently derives ~16% of its electricity from nuclear fission which constitutes a significant proportion of our low-carbon power. For this to continue, and for our energy use to be decarbonised as is planned, new nuclear plant will be needed well into the future. The UK's history as a nuclear fission pioneer has left a legacy of spent nuclear fuel (SNF) in storage that is projected to grow to 6200 teU of UO2-based fuel over the lifetime of the national Advanced Gas cooled Reactor (AGR) fleet and the Light Water Reactor (LWR) at Sizewell. If new build is implemented to current projected capacity, this will lead to a further ~16,000 teU of UO2-based spent LWR fuel.Depending on the policies of individual nuclear nations, SNF is either reprocessed or destined to be disposed of in Geologic Disposal Facilities (GDFs). Development of advanced, safer reprocessing cycles or safe wet/dry storage, retrieval and subsequent consignment to GDF requires a detailed understanding of the evolution and behaviour of SNF under conditions relevant to those activities. In the UK, the very high radiation fields arising from real SNF prohibits their study in all but a few specialised "hot cells" operated by Sellafield or NNL. This access is necessarily resource constrained, so impeding the advancing of knowledge in key areas of SNF research.One way to obviate this problem is to work on simulated SNF (SIMFUELs) consisting of e.g. specially prepared UO2 (depleted) pellets with the same microstructures expected for real SNF with chemical components added to simulate plutonium and fission products formed in-reactor. Ready availability of a wide range of SIMFUEL compositions would both accelerate and enhance understanding of the relative roles of different phases in SNF and mechanistic understanding of key fuel behaviours. Currently, SIMFUEL fabrication in the UK is only conducted at NNL, which again presents access issues. Thus, the vision for this proposal is to establish a university facility for SIMFUEL fabrication & characterisation - a facility that will be unique within the UK HEI landscape and, by offering open access to external users, will serve to drive and accelerate UK SNF research. Reflecting the fuel used in the UK's current AGRs & LWR, and to be used in new build LWRs, our focus will be on oxide SIMFUELs - although, with an eye to future fuel cycles, this will include MOX and ThO2-based fuels. The proposed facility will therefore initiate, support and enable research in the following themes:Theme 1: The development of new, advanced sintering routes for the fabrication of SIMFUELs with porosities, fission product loadings, and defect microstructures that better simulate those of real SNF.Theme 2: Study of the behaviour of these advanced SIMFUELs, as well as those prepared using conventional ceramic processing techniques, under a range of conditions relevant to the back end of the fuel cycle - including wet/dry interim storage, geologic disposal and new reprocessing routes.Potential academic users include any concerned with the fundamental physical, chemical and materials properties of SNF, its storage, recycle and disposal. This includes not only the decommissioning / disposal focussed EPSRC TRANSCEND Consortium and the BEIS-funded National Nuclear Innovation Programme in Recycle and Waste management, but also those nuclear CDT students working in this area. Industrially, we have already sequestered interest from RWM Ltd, NNL and Sellafield who would wish to commission the fabrication of samples on a more flexible basis than currently available. To have such a national facility will be a great enabler not only for UK users but also for fission research collaborators from overseas as some international laboratories report great difficulty in getting access to SIMFUEL samples that can be produced & delivered quickly and in a range of compositions iteratively informed by on-going research programmes.