What future for fusion in the UK?
An alternative to power generation by nuclear fission, which currently supplies 10% of the world’s electricity, is nuclear fusion, which uses the isotopes of hydrogen, tritium and deuterium, as fuel. Fission uses uranium.
The difference in fuel means the radioactive waste from fusion has a shorter lifetime than that from fission and so simplifies long-term waste handling. Unfortunately, fusion reactions are more difficult to initiate and contain than fission, meaning the power stations must be much more complex and expensive. While fission has produced electricity on world-wide grids for 70 years, fusion has been in a research and development phase during the same period. Despite the long timescale for achieving fusion power, there are still enormous numbers of development projects around the world.
The UK has been active in fusion research since the beginning. However, following Brexit, we left the longstanding international fusion project ITER, located in France. In addition, the JET fusion project, located in the UK, was closed down. This left us without involvement in a large-scale fusion project.
To fill this gap, the UK Atomic Energy Authority (UKAEA) proposed the Spherical Tokamak for Energy Production (STEP), to be built at West Burton in Nottingham, on the site of a decommissioned coal power plant. The completion date is said to be 2040. The budget of STEP has not been announced but, given the known machine parameters, the total cost of the project must be several billion pounds. This post explores if such a large investment in such a speculative project is justified in the current economic crisis, and concludes it is not.
There are currently about 90 operational fusion devices in 50 different countries around the world, of which 3 are in the UK. 40 more are under development. Among the operational projects, there are more than a dozen different technologies used, including 51 tokamaks, 9 stellarators and 8 laser fusion devices.
Tokamaks – the most popular approach – are mostly either in the ‘conventional’ shape of a doughnut, or ‘spherical’. JET and ITER were conventional tokamaks, but STEP is to be spherical. This choice, and the timescales, raise serious questions.
The shape of the spherical tokamak design – it is something like a cored apple – should greatly improve the longevity of the device – a major problem with conventional equivalents, although it remains to be seen if it will improve it enough to allow for commercial operation. [1] However, it may prevent efficient refuelling operation.[2]
The short timescales envisaged for STEP to reach commercial operation are unusual in the public sector, although common among the many private fusion companies, which have from around 2000, been launched alongside increasingly implausible claims about their ability to quickly deliver commercial fusion power. The experience of ITER, which is now at least ten years behind schedule, having spent about 50 billion euros, suggests that few of these – or STEP – will deliver on their promises. Moreover, the amount of electricity produced will be negligible for a long time. STEP aims for 100 MW of output – just 0.2% of UK peak electricity demand – and this would be intermittent. In reality, commercial fusion is probably at best 50 years in the future.
The STEP project is therefore highly speculative. Nor is it unique; there is a large number of spherical tokamaks projects around the world. Two of them are in the UK: the UKAEA’s MAST upgrade, which started up in 2020, and the ST40, run by a private company called Tokamak Energy, which started operations in 2018. Another UK company, First Light Fusion, is working on a very different ‘inertial fusion’ design.
The need for the UK taxpayer to fund a project that is not unique and for which success is far from assured is highly questionable. When the private sector has already stepped up to the mark, it seems crazy. Public research agencies should fund activities that do not attract venture capital. The STEP project should be cancelled as soon as possible, leaving UKAEA to concentrate on smaller projects such as the nuclear robotics RACE Centre, and to return to its original mission of basic research into nuclear fission technologies.
Editor’s note: The Secretary of State has today announced a £410 million investment in the STEP project.
Notes
[1] Fusion reactors work by creating highly reactive plasma, which has to be contained using powerful magnetic fields. Conventional reactors have frequently experienced so-called ‘disruptions’, when they are damaged by escaping plasma. This problem will be greatly reduced by spherical designs. However, disruptions need to fall to zero for commercial operation.
[2] Fusion reactors run on tritium (an isotope of hydrogen), which after initial seeding from outside, has to be generated in the reactor itself. However, the shape of STEP may mean that tritium generation (‘breeding’) is inadequate.