Reducing risk through uncertainty quantification for past, present and future generations of nuclear power plants

To ensure national resilience and productivity in an uncertain world, the UK needs a safe, reliable energy supply. Electricity generated by domestic nuclear fission plant creates an important contribution to this, currently generating around one sixth of the UK's requirements. Future fusion-powered plant provide a vision of lower waste, higher safety energy generation from essentially limitless fuel.

However, poor public perception of nuclear safety is limiting uptake, whilst poor understanding of the behaviour of critical nuclear materials exposed to thermal, mechanical and radiation loading increases engineering uncertainty, hence escalating design risk and operational cost.

This programme of research uses a multi-scale, multi-technique approach, combining high performance computer models with imaging analysis, to build a deeper understanding of the mechanical behaviour of several vital engineering materials subject to such stresses:
* silicon ceramics used for the containment of historic nuclear waste,
* graphite used for moderating reactions in the current generation of nuclear plant,
* beryllium and tungsten used to line containment vessels for future fusion generation.

Developing better, experimentally-validated models of the structural integrity of such vital components will enable increased accuracy in design, hence reducing the cost of build and operation of power generation and waste storage facilities and giving greater public confidence in the industry.

The research combines the strengths of two computational approaches:
* Fully physically-based materials models, which are well-developed, but are not yet applicable to large and complex engineering systems;
* Empirical engineering models, which are useful in the domain for which they have been calibrated, but currently have limited transferability;
along with rigorous error analysis, to create an approach that is transferable across length scales, enabling the tracking of fundamental physical mechanisms through to engineering application.

The experimental elements of the programme, using X-ray tomography to create 3D images of strain and damage inside samples and Digital Image Correlation to track real-time crack propagation, will provide new insight into the behaviour of these critical materials under stress and observational parameters to inform the modelling.

The project will draw from the strengths of the interdisciplinary team to develop experts of the future. It will involve and inform industrial partners and other key stakeholders, from regulators to plant workers, to ensure results are relevant to and taken up by UK energy generation and other strategically important industries.

Planned Impact
In addition to the knowledge and people impacts generated, described in the academic beneficiaries section above, the research programme also generates economic and societal impact for a wide range of stakeholders and end users who will benefit from its outcomes.

For national resilience and productivity, the UK requires reliable baseline power generation. This has been put at risk through the phase out of conventional fossil fuel plant in line with international carbon reduction obligations, with increasing dependence on variable renewable resource. Threats of "brown outs" and load management through reduction of factory operating hours are leading to UK concerns about quality of domestic energy supply and reliability of industrial processes. In addition, the need to reduce reliance on overseas power supplies becomes ever more important given the uncertain global political situation. Hence research programmes such as this, which improve the reliability and safety of domestically-generated energy and accelerate the fission to fusion transition, are of vital national importance.

The owners and operators of existing power plant and waste storage facilities, from government agencies such as the Nuclear Decommissioning Agency to private companies such as EDF, will directly benefit from this research programme through a better understanding of expected behaviour of critical engineering materials, leading to safer and more effective processes and hence greater public confidence in and acceptability of nuclear power generation.

More widely, connections between the research team and their existing collaborators in national, European and wider international institutions such as Culham Centre for Fusion Energy, the National Nuclear Laboratory, the French Alternative Energies and Atomic Energy Commission (CEA), and Lawrence Livermore and Los Alamos National Laboratories, will ensure strong uptake of results, hence increasing safety nationally and globally.

Whilst the primary focus of this project is the nuclear industry, the generality of the fracture problem is such that the methodology and results can also be extended to other industries where fracture is a concern, and which BEIS recognises as strategically important, thereby further strengthening UK industrial strategy. This includes aerospace, shipbuilding, defence, renewable power and other fields where high strain rate is a concern. Thus stakeholders such as AWE, BAE and Rolls Royce will also benefit from research outcomes.

Collaboration with the Health & Safety Executive, through project interactions with staff from HSE's Health & Safety Laboratory, will enable results of the fracture tests to be incorporated into regulation around handling and use of demanding materials, such as beryllium and irradiated graphite, in the industrial environment - hence improving industrial safety standards.

All these stakeholders will be engaged through the Advisory Panel, the communications programme and other activities described in the Pathways to Impact section that follows.