The UK challenge - developments in materials nuclear research facilities
Professor Andrew H Sherry is Director of the Dalton Nuclear Institute at The University of Manchester. Here he discusses the developments in UK materials nuclear research facilities.
The UK is developing challenging plans to move towards a low carbon economy that will deliver an 80% reduction in CO2 emissions by 2050. Aligned with this target, the UK energy mix is shifting. Greater reliance is being placed on low carbon electricity generation that includes nuclear power and renewables. As highlighted in the recent House of Lord’s report on nuclear research and development capabilities, this shift creates both challenges and opportunities. The contraction of expertise and facilities over the last 25 years has made it a challenge to deliver the necessary materials research to address nuclear issues. However, targeted investment in UK research facilities over the last five years has created opportunities for the materials community to engage in research again.
Materials research and development is required to address the grand challenges of the UK nuclear programme, including:
- plant life extension
- new nuclear build and future reactor systems
- nuclear fuel cycle
- radioactive waste management and disposal
Cross-cutting these challenges are materials research issues relating to component manufacture and performance. Manufacturing innovation will enable components to be fabricated using cost-competitive and energy-efficient technologies that deliver high quality and reliability. Materials performance research will develop the new understanding needed to ensure the reliable operation of nuclear components during and beyond their design lives.
Nuclear component manufacture
According to the World Nuclear Association, 60 nuclear power stations are being built in 14 countries around the world, with more than 150 planned and 340 proposed. The scale of this new nuclear build creates a significant opportunity for the UK manufacturing sector. One example is the pressurised water reactor (PWR), which is fabricated from materials including ferritic steel forgings, stainless steels, nickel-based alloys and a range of welds, including transition welds. The opportunities to develop and deploy new manufacturing technologies into new plant are many, and can have a positive effect on the UK supply chain.
Key areas include:
- innovative joining – research into improved arc welding and alternative joining technologies such as laser, laser hybrid and electron beam welding will help to improve the speed, quality and reliability of welds
- advanced machining – research into the link between machining parameters and surface engineering will help to deliver components that are more resistant to the initiation of defects in service
- near-net shape manufacture – research into processes including hot-isostatic pressing and shape-welded additions will optimise the shape and function of nuclear components
These manufacturing research challenges are being addressed within new facilities at the Nuclear Advanced Manufacturing Research Centre (Nuclear AMRC), a collaboration between the Universities of Sheffield and Manchester. With more than 30 industrial partners – including reactor vendors and manufacturing companies – state-of-the-art manufacturing, testing and analytical laboratories and an 8,000 m2 R&D factory, the Nuclear AMRC is driving manufacturing innovation from research through development to deployment. Coupled with this, the world-leading ISIS Engine-X engineering materials beamline provides neutron diffraction capability for internal stress measurement, including weld residual stresses.
Nuclear component performance
The reliable operation of a nuclear plant relies on high quality materials processing and manufacturing technologies, and the capability to assess and predict in-service degradation. This requires materials test data generated under relevant environmental conditions, and a fundamental understanding of degradation processes.
The 2010 Materials UK report on materials R&D for nuclear applications highlighted two research priorities:
- understanding mechanisms of material corrosion in-service, including behaviour within nuclear power reactors
- understanding and predicting radiation effects on materials, including microstructural, microchemical, and environmental aspects
Advancing mechanistic understanding and predicting in-service degradation requires access to specialist facilities where relevant materials can be exposed to the extreme environment of nuclear power reactors and examined. For corrosion studies, active loading autoclaves with advanced chemistry control are available in a few UK industrial and academic centres of excellence. Such facilities require specialist knowledge and advanced techniques to monitor oxide formation, crack initiation and growth. Of particular note is the development of the imaging autoclave in which the specimen surface is observed during active loading in high temperature pressurised water. The application of digital image correlation enables the initiation of stress corrosion cracks to be directly observed from surface strain maps and correlated with predictive models.
Materials irradiation research presents a greater challenge to the UK materials community because of the specialist facilities and costs associated with handling radioactive materials. The facilities at the National Nuclear Laboratory’s Central Laboratory offer the capability to undertake active materials R&D, and access to 10% of these facilities is now available to UK academic researchers through a third party user process facilitated by the Nuclear Decommissioning Authority. Active materials research is costly and two novel approaches are now available to expand the UK radiation research capability.
First, extracting microscopic volumes of material from radioactive components enables samples to be handled outside active facilities. Irradiated material can be examined within analytical facilities, such as the 3D Local Electrode Atom Probe (LEAP) at the University of Oxford. This approach is enabling the development of a fundamental understanding of in-service changes in the materials structure. The second approach is to employ ion beam facilities to simulate the influence of neutrons on materials using high-energy protons and heavy ions. The University of Manchester’s new Dalton Cumbrian Facility (DCF) opened in October 2011, and when fully operational, will offer the capability to undertake radiation studies as a National User Facility. At its heart is a 5MV tandem ion-beam accelerator capable of supplying 10MeV protons, 15MeV helium ions and a variety of partially stripped heavy ions. Supporting materials laboratories facilitate the development of new understanding of materials subjected to radiation.
Materials R&D is critically important to the UK and global nuclear energy programme, with challenges and opportunities existing across the full nuclear lifecycle. For new nuclear build, the opportunity exists to develop and deploy new manufacturing techniques within the UK supply chain. For operating plant, new understanding of materials degradation will enhance component reliability in the aggressive environment of a nuclear reactor. A number of major new facilities for materials R&D have been established that will enhance the UK materials research community and help them to contribute significantly to the global nuclear renaissance.
The new nuclear R&D facilities highlighted in this article have been made possible through strategic investment by a number of bodies, including Central and Regional Government, the Research Council UK, the Nuclear Decommissioning Authority, the National Nuclear Laboratory and The University of Manchester.