Experimental Actinide Nano-chemistry for the Future of the Civil UK Plutonium Inventory

In the UK, electricity generation using Nuclear Power is key to energy security and to achieving Net Zero. After six decades of commercial nuclear fuel reprocessing by Sellafield Ltd (SL), the UK has the largest inventory of civil plutonium (Pu) worldwide. The current and future management of the UK's civil Pu inventory by SL on behalf of the Nuclear Decommissioning Authority (NDA) is one of the most important challenges presented by nuclear decommissioning. The difficulty and scale of the challenges are reflected in the provision of funding: £2 billion for the retreatment plant, £4 billion for storage until 2120, and £10 billion for future Pu management. The Pu inventory is in the form of actinide oxide AnO2 (An = uranium U, or Pu) or mixed-actinide oxide powders (MOX) and stored in gas-tight packages on the Sellafield site. Research commissioned by SL, undertaken by the National Nuclear Laboratory (NNL) at Central Lab, has revealed that there is a significant knowledge gap in the chemistry of actinide oxides. The data cannot currently be explained and show that the properties of the AnO2 have changed during storage. This has led to concerns about safety, and how to handle these materials going forward. Moreover, there is an urgent need to establish optimal operating conditions for Pu inventory retreatment and repackaging, which is scheduled to begin in 2027, and to ensure safe and secure inventory storage from 2027 onwards.
This knowledge gap results from the complexity of Pu chemistry under industrial conditions, and the difficulty of experimental studies. My insight is that not only are new experimental actinide materials needed, but so are new ways of studying them. This has been developed and informed through my recent secondment at SL, and working closely with key stakeholders (SL, NNL, NDA). The FLF will enable the synthesis of a new class of actinide nanomaterials, with broad application potential in nuclear decommissioning. This Fellowship will provide crucial experimental data on actinide structure and bonding on an atomic level, which has previously only been possible to study theoretically. Catalysis technology will be used to probe and quantify reactivity of actinide nanomaterials with problem industrial contaminants. This is also the first application of knowledge and technologies used in industrial catalysis to address nuclear industry technical challenges. This work is in partnership with SL and NNL and has been designed to generate data directly comparable to ongoing industrial work. Advanced characterisation and reactivity studies will be supported by the development of new spectroscopic tools. Synchrotron and neutron science will be utilised, ultimately in combination with vibrational spectroscopies, and in operando experiments. These studies will be a world-first. The impact of the FLF science will be realised through working in partnership with industrial stakeholders both in the UK (SL, NNL, NDA) and internationally through joint UK/US programmes (Los Alamos National Laboratory) and the European Commission Joint Research Centre (Karlsruhe). The translation of scientific knowledge to meet real end-user needs in nuclear decommissioning is a major goal of the FLF. This will be achieved by contributing to the scientific evidence base, therefore informing safety cases, engineering designs, and ultimately future UK government decision-making on Pu management.