Hot topic: the future of fusion

Just imagine a source of energy that generates no carbon emissions and has millions of years of fuel. Sound too good to
be true? Well maybe not; a worldwide research programme is making real progress into developing the process of nuclear fusion into a viable electricity source for the years after 2050.

The fusion, or sticking together, of deuterium and tritium nuclei (heavy isotopes of hydrogen) has long been known to release huge amounts of energy. It is inherently safe and produces short-lived radioactive waste compared with nuclear fission. However, fusion is very difficult – temperatures ten times hotter than the core of the Sun (a staggering 150-200 million degrees C) are needed in the gaseous fuel or ‘plasma’, before the nuclei fuse and release their energy.

Culham leading the world

The most promising route to harnessing the power of fusion is using strong magnetic fields to control and confine a ring-shaped plasma at these temperatures inside a machine known as a ‘tokamak’. The UK Atomic Energy Authority (UKAEA) runs two tokamaks – JET and MAST – at its Culham site near Oxford. JET is Europe’s tokamak and remains today – more than 30 years after its first experiments – the largest and most powerful fusion device in the world. Back in 1996, JET achieved the world record for fusion power produced, 16MW, some 70% of the power needed to heat the plasma.

JET continues to push the boundaries of fusion research today – currently preparing for experiments in 2019/20 which aim to use the optimal fusion fuels, deuterium and tritium, to sustain high fusion powers for much longer periods. JET experiments continue to be fundamental to the design and operation of its successor, Iter – a collaboration between Europe, Japan, China, US, 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 produce 500MW of fusion energy; approaching power plant scale.

By the mid to late 2030s, Iter will be informing the design of the first true fusion power station, DEMO, which it is expected will start up in around 2050.

In addition to JET, UKAEA also hosts the UK’s own fusion experiment, MAST at Culham. With a more compact and efficient ‘spherical tokamak’ design, MAST is exploring the spherical tokamak as an innovative reactor design for a second or third generation fusion power plant. Presently coming to the end of a £45 million major upgrade, the new MAST Upgrade when it starts operation later this year, will specifically test technologies, notably plasma exhaust systems, for DEMO and the first commercial power stations.

Demanding engineering

Whilst creating artificial stars for energy may sound difficult, because of JET, MAST Upgrade and other tokamaks, the science is now relatively well understood. The largest challenges on the path to realising economically viable fusion power stations lie in advanced and very demanding engineering. Solving these engineering challenges will ultimately determine whether fusion is putting electricity on the grid in the years after 2050 or remains the domain of science fiction movies.

Addressing these challenges head on are two brand new facilities at Culham – the Remote Applications in Challenging Environments (RACE) centre and the Materials Research Facility. RACE exploits UKAEA’s expertise in robotic maintenance inside JET and is working with UK consortia to develop remote handling systems for Iter and Europe’s proposal for DEMO. RACE has already enabled UK plc to win contracts worth well over £100 million. Meanwhile the Materials Research Facility specialises in materials testing at the nanoscale – key in developing specialist materials that can withstand the very high-energy neutrons produced by fusion reactions.

The future looks bright

Presently two-thirds of UKAEA’s funding comes directly from Europe to operate JET, and whilst funding is secure till the end of 2018, Brexit makes planned operation up to 2020 and beyond more uncertain, but UKAEA is working closely with the UK government to make sure that the investment in JET up to now is not squandered. Sooner or later of course, JET will close, but the investment in MAST Upgrade and in Culham’s robotics and materials facilities will ensure the UK remains a key player in the programme to develop commercial fusion. Indeed, UKAEA is determined to become a major design centre for the European DEMO device, ensuring that Europe remains world leading and UK industry capitalises from this multi-billion pound energy technology of the future.

Furthermore, the benefits to nuclear extend beyond fusion. RACE’s design expertise and testing facilities are supporting the much wider robotics and autonomous systems community, which includes 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 the UK and Europe continue to be a pioneer in fusion research and also benefit more generally from the nuclear renaissance – vital for the low-carbon economy we all strive for.