An Atomic-Scale Characterisation Facility for Active Nuclear Materials

The design, build and maintenance of next generation fission and fusion reactors must be underpinned by research into how materials for their construction will degrade when exposed to the harsh reactor environment. This deterioration is largely driven by the extensive bombardment of high energy neutrons, which both damage the structure of the materials, and ultimately over extended periods can transform it, changing its properties. This process is initiated at the atomic level. Hence a better understanding of how the microstructure evolves, from this scale, under the combination of extreme temperature and irradiation conditions within the reactor, and correlating this to the deterioration of mechanical properties, is essential to predict safe operating lifetimes of critical components.
This proposal is to establish a state-of-the-art Active Atom Probe Facility as a national user facility for UK researchers. Atom probe tomography (APT) is a type of microscopy that provides unique insight into 3D atomic distributions within materials at a scale that even the most advanced electron microscopes cannot routinely achieve. APT can be used to identify and characterise the very onset of irradiation-induced damage in nuclear materials. It is now an indispensable materials characterisation tool utilised in a wide variety of research and development into nuclear materials.
APT is a destructive characterisation technique, meaning that when active specimens are analysed, during the experiment sample material will be deposited within the instrument. In the case of active materials, this represents serious logistical and safety concerns for the maintenance and operation of the instrument. Hence, for UK researchers to undertake such analyses routinely, effectively and safely requires the establishment of an APT facility dedicated to the characterisation of radioactive materials.
The Active Atom Probe Facility represents a collaboration between the University of Oxford and the UKAEA's Materials Research Facility (MRF) to maximise the effectiveness of UK expertise and infrastructure. While the atom probe instrumentation will be installed at Oxford, prior to analysis APT specimens must be prepared from larger, significantly more radioactive samples. This will be undertaken utilising a Focused Ion Beam instrument to be installed at the MRF, which has the experience and facilities for safe handling, preparation and examination of irradiated reactor materials.
This Active Atom Probe Facility will provide fully-supported access and training to scientists from UK academia and industry across every step of the APT experiment, from specimen preparation through to data analysis and interpretation of the results. Users of the new instruments will be trained to an expert level in all aspects of the technique, with an emphasis on all specific precautions required to undertake experiments radioactive materials. It will therefore play a key role in the development of the next generation of UK scientists who will contribute to re-establishing international leadership in nuclear materials research. Access to this unique capability will support research across a range of different stages in the fission and fusion nuclear energy cycle, including: design and manufacture of new irradiation resistant materials for next generation reactors, contributions to safety critical reactor monitoring, validating ion/proton irradiation as a neutron surrogate, developing effective, long-lasting waste storage solutions and steering research for future fusion plants.

The Active Atom Probe Facility will underpin research into design and manufacture of new materials across a wide range of nuclear materials applications, under a variety of EPSRC themes, such as Physical Sciences, Manufacturing the Future, Engineering and Energy. This highlights a key reason for the recent growth in influence and impact of APT, namely a rapid broadening in the range of research topics which require 3D atomic-scale chemical information to develop the next generation of high performance materials. This is evident in the fact that nuclear materials research already accounts for more than half of current APT usage in the UK, despite access for the analysis of active materials being highly constrained. Given the critical effects that neutron irradiation has on the in-service performance of structural reactor materials and waste-forms, and the increasingly prominent role of APT in UK nuclear materials research, it is clear that the Active Atom Probe Facility will have immediate, and long-term impact in this area.
A central feature of our vision for the new facility is that it will deliver important, novel results and understanding to university partners and their industrial collaborators. This is not an activity that will have to be built up from scratch, as many of the investigators already hold a substantial portfolio of projects funded by UK industry. However, the range, depth and significance of output on problems related to the design and performance of nuclear materials that are scientifically extremely challenging and of direct and immediate commercial relevance will be substantially increased by the availability of this unique facility. With academic partners, we will generate impact by output of first class papers in the scientific literature.
Access to the new Active Atom Probe Facility will also benefit researchers at earlier stages of their careers, ensuring adequate access for them to explore ambitious lines of new research. A key emphasis will be placed on training. Users of the new instruments will be trained to an expert level in all aspects of the technique. Furthermore, the MRF provides an excellent training ground for young researchers to learn all aspects of how to safely plan and run experiments using radioactive materials. Hence it will play a vital role in training and development for the next generation of students and ECRs who will take up nuclear-focused roles in UK academia and industry. This is critically important in the field of nuclear research where there is emphasis on re-establishing technical competency and international leadership.
More than 8 UK and international companies are actively involved in projects outlined in this proposal. These collaborators share ambition to use the new facility to underpin development of next-generation materials across a range of nuclear engineering applications. The new facility will make critical contributions to multi-institutional collaborative research programmes, supported by both UKRI and industry, with the potential for immediate real-world impact to manufacturing in the UK.
Examples of projects that we plan to undertake with these industrial partners underpins materials research across many different stages in the nuclear energy cycle: examining structural materials for GenIV reactors, contributing to safety-critical monitoring of reactor steels, developing effective waste storage solutions and steering research for future fusion plants. Furthermore, we are continually in discussion with new partners who have problems that will benefit from the access to unique insights offered by the new instrument.
Another important impact of this project is to ensure that academia and industry has access to competitive facilities within the UK. Without this, there is real risk that industrial partners could move entire projects, not just the APT aspects, to international competitors who are actively installing similar facilities.