Improving the safety, security and reliability of the UK’s nuclear industry
Research by Manchester's Nuclear Graphite Research Group has helped to ensure the safe continued operation of the UK's ageing advanced gas-cooled (AGR) nuclear reactors by up to ten years.
Working with bespoke technology
Around 18% of the UK’s electrical power is generated by graphite-moderated AGRs licenced by EDF Energy Nuclear Generation Limited. They are between 30 and 40 years old and well beyond their design life of 25 years.
Maximising the lifespan of AGRs is critical: they are expensive to replace and integral to our electricity supply. However, these face life-limiting factors which could affect their safety. Over time, the AGRs' irreplaceable core can start to degrade and affect its structural integrity.
The Office for Nuclear Regulation (ONR) require EDF Energy to demonstrate, through their safety case, that they have adequate understanding of the material changes to the graphite and their rate of progression, to ensure safe operation of the core.
Currently, the UK is the only country to employ AGR technology as most of the world uses pressurised water reactors. This means, while other regulators can share knowledge and expertise as a global community, the ONR is alone and reliant on developing its own, UK-based community to advance its knowledge.
Advancing nuclear knowledge and skills
To help the ONR combat these challenges, the Nuclear Graphite Research Group (NGRG) was created: an independent panel of graphite experts, led by Professor Abbie Jones and based at The University of Manchester.
The NGRG, the largest pool of expertise in graphite in universities worldwide, conducts research to develop independent models and provide advice. Using advanced modelling and simulation, and the development of material model, the NGRG can undertake stress analysis – that is completely independent from EDF Energy – to give ONR the impartial evidence to verify or challenge the licensee’s safety case, and ultimately ensure the safe operating of reactors.
The NGRG created bespoke facilities and software to create a UK hub of expertise on nuclear graphite so they can advance their research capabilities. It has created independent software (ManUMAT) with several statistically based models to carry out structural analysis of graphite and established new laboratories for handling irradiated graphite at the University's Henry Royce Institute.
In supporting the UK regulator, the NGRG have investigated mechanisms of graphite behaviour that were previously impossible or impractical to conduct. This has included establishing novel approaches to nuclear graphite research, spanning multiple aspects of graphite core degradation, such as core weight loss, brick cracking and oxidation lifetime behaviour.
Additionally, the Group has discovered microstructure/property relationships and identified and shared ways to extend reactor operating life by up to ten years by assessing the structural integrity of reactor graphite components and understanding age development processes.
At the forefront of nuclear graphite technology
The NGRG has helped to deliver an economic impact valued at £1.5 billion per year by extending the operational lifetime of nuclear reactors. As well as supporting an annual UK supply chain income of around £650 million and 2,000 jobs.
The continued safe operation of EDF’s AGRs has saved more than 17 million tonnes of CO2 emissions each year – the equivalent of taking 7.5 million cars off the road, in addition to enabling the UK to save up to £745 million in excise from the Climate Change Levy.
The UK is at the forefront of the nuclear graphite community worldwide due to the NGRG's research. NGRG has been able to investigate the mechanisms of graphite behaviour and will continue to undertake this research to support the development of high-temperature gas-cooled reactors which also use graphite advancing the UK towards net zero and clean energy generation.
The NGRG openly shares its knowledge with the ONR, government bodies and the public through technical and peer reviewed reports, publications and presentations. They’ve also created a bespoke nuclear graphite technology course aimed at building professional capability within the nuclear sector.
The Group's commitment to enhancing the skills of the nuclear workforce has contributed to the UK's net zero ambition by enabling AGRs to continue producing low-carbon electricity while providing the UK with the expertise to build, operate and maintain high-temperature gas-cooled reactors – the government's preferred advanced reactor technology for the future.