Imagine an energy source that generates no carbon emissions and has fuel for millions of years just in the water that surrounds us. Sounds too good to be true? Maybe not. A world-wide research programme is making good progress on developing just such a process – nuclear fusion, the power source of the sun and stars – into a viable electricity source for the years after 2050. And the UK Atomic Energy Authority’s fusion lab at Culham, in the science hotspot of South Oxfordshire, is leading the world in this highly promising field.
The fusion, or sticking together, of the nuclei of hydrogen isotopes has long been known to release huge amounts of energy. It is an inherently safe process and only produces short-lived radioactive waste. Perfecting fusion is one of the most enduring – and elusive – quests in science. Getting it to happen is very difficult – temperatures ten times hotter than the core of the sun (a staggering 150-200 million degrees Celsius) are needed in the gaseous fuel or ‘plasma’, before the nuclei fuse and unlock their energy.
The most promising route to harnessing the power of fusion is using strong magnetic fields to control and confine a ring-shaped body of plasma at these temperatures inside a machine known as a ‘tokamak’. Among the forty or so tokamak experiments working collaboratively worldwide, two of the most important are at Culham.
UKAEA operates the world’s largest tokamak, JET, on behalf of European fusion researchers. JET is the only fusion experiment capable of using the optimal fusion fuels, isotopes of hydrogen – deuterium and radioactive tritium. It routinely heats and holds plasmas at the temperatures required for fusion. Indeed, JET holds the world record for fusion power produced, at 16 megawatts; though this was only 70% of the power needed to heat the plasma.
Progress on JET has enabled the design of its successor, ITER – a collaboration between Europe, Japan, China, USA, South Korea, India and Russia, which is currently under construction at Cadarache in the south of France. Bigger and more powerful than JET, ITER will when started in 2025 produce 500MW of fusion energy (approaching powerplant scale) and tackle some of the engineering challenges – such as advanced materials, robotic maintenance and superconducting magnets – standing in the way of commercially viable fusion power stations.
The UK’s own fusion experiment, MAST, is also answering vital questions. With a more compact and efficient ‘spherical tokamak’ design, MAST is presently undergoing a wholesale upgrade. When MAST Upgrade starts operation in late 2017, it will further explore the spherical tokamak as an innovative reactor design for a second or third generation fusion power plant. In the shorter term it will start to test technology for the power stations that will directly follow ITER; for example an innovative exhaust system designed to extract hot waste from the plasma without damaging its surfaces. Successful experiments on MAST Upgrade in this area could have a big impact on the design and economics of the first fusion power plant – the ‘DEMO’ reactor currently being designed in the EU.
Whilst creating artificial stars for energy may seem difficult, the science is now well understood. The largest challenges on the path to realising economically viable fusion power stations lie in advanced and very demanding engineering; building the box to put the star into. Developing and integrating these engineering systems will ultimately determine whether fusion is putting electricity on the grid in the years after 2050 or remains a plot line in science fiction films.
Two brand new UKAEA facilities – the Remote Applications in Challenging Environments (RACE) centre and the Materials Research Facility – are working with industry and academia on some of the most pressing challenges. RACE exploits JET’s expertise in robotic maintenance and is working with UK consortia to develop remote handling systems for ITER and DEMO, enabling UK plc to win contracts worth well over £100million so far. Meanwhile the Materials Research Facility specialises in materials testing at the nanoscale – key in developing reactor structures that can withstand the very high energy neutrons produced by fusion reactions.
Both are vital for the future of the international fusion research programme, but also for Culham as a world leading research centre. JET is the only major European science project on UK soil, and with two thirds of UKAEA’s funding coming directly from the European Commission to operate JET, the UK’s decision to leave the EU is felt more keenly at Culham than almost anywhere else.
Whilst funding is secure until 2018, further vital work on JET to prepare the way for ITER is less clear. Detailed discussions with UK Government are just starting to find a way for the UK to remain fully within Euratom (Europe’s nuclear research treaty, which is outside the European Union Treaty) and hence secure JET operation well into the 2020s.
Sooner or later, JET will close, but the investment in MAST Upgrade and in Culham’s robotics and materials facilities will ensure Britain remains an important player in the programme to develop commercial fusion. In addition, UKAEA intends Culham to become a design centre for the first fusion power stations, ensuring that the UK and its industry capitalises from this multi-billion energy technology of the future.
The benefits to the UK extend beyond fusion. RACE’s design expertise and testing facilities are supporting the much wider robotics and autonomous systems community, which includes space, deep sea exploration and the nuclear fission industry. Similarly, the Materials Research Facility’s capabilities are deliberately synergistic with the testing of fission materials; vital in areas such as advanced reactor design activities and lifetime extension of existing nuclear plant.
These technology growth areas at Culham will ensure that we continue to be a pioneer in fusion research and help the UK to benefit from the nascent nuclear renaissance – vital for the low-carbon economy we all strive for.
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