UTGARD LAB PHASE II: A SIMFUEL FABRICATION & CHARACTERISATION FACILITY

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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.