The future is fusion.
And it starts here.

A giant step-change for humankind.

The first of its kind, STEP is the UK’s major technology and infrastructure programme to build a prototype fusion powerplant that will demonstrate net energy, fuel self-sufficiency and a viable route to plant maintenance. 

This will pave the way for the potential development of a fleet of future fusion powerplants around the world and the commercialisation of fusion energy. 
 
We’ll achieve this by producing a prototype tokamak powerplant — in an innovative spherical shape — that will demonstrate net energy. That’s why the programme is called STEP: it stands for ‘Spherical Tokamak for Energy Production’.  
 
But STEP is about more than tokamak technology — it’s a huge endeavour encompassing design, site development and construction, alongside supply chain logistics and industry. Fusion research and development has the potential to catalyse new ideas and technologies that will benefit multiple industries and help secure our future on this planet.  
 
By fusing government and business, inspiration and pragmatism, theory and practice, UK-expertise and international impact, we’re going to realise the step-change that will secure humanity’s bright future.

Digital view of Earth at night, with glowing city lights outlining continents against the blackness of space.

why fusion?

Humanity faces a future of severe challenges. If we want to continue to flourish, we need revolutionary new technology. That technology is fusion.

By harnessing the process that powers the Sun and stars, fusion has the potential to provide a safe, abundant source of low carbon energy.  
 
It’s also remarkably clean. Fusion is carbon-free at the point of generation. The process itself produces no carbon emissions — the waste product is helium, which doesn’t contribute to global warming. Currently, carbon is used to manufacture the components and buildings needed to start up a power plant — but there’s already a focus on reducing this.  
 
Ultimately, fusion could be an environmentally responsible part of the world’s energy supply in the second half of this century.

How fusion works:

Harnessing the power of the sun and stars.

A combination of hydrogen gases — deuterium and tritium — are heated to over 100 million degrees Celsius (that’s 10 times hotter than the core of the Sun) in an advanced device called a tokamak.

Computer-generated cross-section of the STEP tokamak concept, with the inner vacuum vessel highlighted in green.

The hydrogen gasses form an intensely hot plasma that is confined with powerful magnets.  Inside this magnetic field, the gasses collide to create Helium and an energetic Neutron.

Computer generated concept of STEP's Tokamak, cut in half so the machine's cross section is visible, with plasma within.

With each combination, as per Einstein’s famous equation E=MC2, a small fraction of mass converts into energy. This ‘fusion’ energy is produced in vast amounts, as millions of these reactions occur in the plasma every second, generating a significant amount of energy from a very small amount of fuel.  Additionally, the neutrons produced in the process interact with other materials in the reactor, which breeds more tritium – and that tritium is injected back into the plasma to promote fuel self-sufficiency. 

Computer-generated cross-section of the STEP tokamak concept, with the breeder blanket highlighted in pink.

This energy is used to create steam, to turn a turbine, generating electricity — just like in any conventional power plant.

Computer-generated cross-section of the STEP tokamak concept, with the divertor regions highlighted in blue.

Fusion power falls to zero in seconds if control of the plasma is lost — there’s zero chance of a ‘runaway reaction’ with fusion (the challenge is sustaining it, not containing)

Computer-generated cross-section of the STEP tokamak concept, with the poloidal field coils highlighted in orange.
Computer-generated cross-section of the STEP tokamak concept, with the inner vacuum vessel highlighted in green.
Computer generated concept of STEP's Tokamak, cut in half so the machine's cross section is visible, with plasma within.
Computer-generated cross-section of the STEP tokamak concept, with the breeder blanket highlighted in pink.
Computer-generated cross-section of the STEP tokamak concept, with the divertor regions highlighted in blue.
Computer-generated cross-section of the STEP tokamak concept, with the poloidal field coils highlighted in orange.

The future’s bright. The future’s pink. And shaped like A cored apple.

STEP’s spherical tokamak design is unique – and revolutionary. Here’s why.

It’s the result of 66+ integrated concepts with 150+ iterations — going through 66 technical decision boards that have taken 165+ decisions.

The plasma inside will form a shape like a cored apple (rather than the ring shape type such as the Joint European Torus). This brings the plasma closer to the wall of the machine, and allows for a more compact tokamak, with smaller magnets. 

STEP’s technical team will have access to Dawn — a UK supercomputer developed by the University of Cambridge, Intel and Dell. They’ll be able to create a next generation ‘digital twin’ for STEP’s design that will speed-up modelling capabilities.

Spherical tokamaks are more space efficient, and produce a higher quality plasma. It’s also possible to build them in a modular way, simplifying the assembly and maintenance process. 

The Phases (or tranches) of the STEP programme

Computer generated concept of STEP's Tokamak, cut in half so the machine's cross section is visible, with plasma within.
Two people at a table, one writing on a document with pen in hand, and the other with clasped hands.
Two construction cranes above a building site, against a dusky sky.

In the first phase, to 2024, we’ve focused on the concept design, development of the organisation to enable us to deliver a major technology and infrastructure programme, selection of a site, and getting the right regulatory framework in place where the UK is world leading.

We now have a concept design for the powerplant: a view on how we’ll design each of the major systems. We also have a site, West Burton in Nottinghamshire.
 
Our current focus is on site characterisation work at West Burton. This includes things like:

  • Ground Investigation (how geology will inform construction).
  • Biodiversity Net Gain (understanding local flora and fauna, and how we can add to the environment overall).
  • Transport (understanding limits, capacity and modelling).
  • Ash characterisation (working out how best to manage large quantities of ash, including recycling some into new construction materials).
Computer generated concept of STEP's Tokamak, cut in half so the machine's cross section is visible, with plasma within.

The second phase develops the programme and the design and demonstrates critical technologies, all with major industry involved, moving into component manufacture.   
 
We will also be working closely with our West Burton local authority collaboration partners and the community surrounding site to secure planning consent and permissions.  

Two people at a table, one writing on a document with pen in hand, and the other with clasped hands.

The third phase is about plant assembly and infrastructure construction which will start in the 2030s, when planning permissions and consents are in place. The prototype plant will commence first operations in 2040 with at least 100MW of net energy demonstrated as soon as practicable

Two construction cranes above a building site, against a dusky sky.

Don’t wish upon a star.
Build one.

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