- Bristol fusion startup Astral Systems has closed a £23M Series A led by Mercia Ventures to scale production of medical isotopes critical to cancer diagnosis and treatment.
- Unlike most fusion companies that are still building toward long-term power generation, Astral already operates reactors and has generated more than £3M in revenue from research contracts.
- More than 50 million nuclear medicine procedures a year depend on a global isotope supply chain with no reliable UK domestic source.
Every year, more than 50 million cancer scans and treatments depend on a handful of ageing nuclear reactors scattered around the world to produce the radioactive materials they need. When those reactors go offline for maintenance, accidents, or end-of-life decommissioning, hospitals run short on supplies, and patients wait.
Astral Systems was founded to fix that, and it just raised £23M to prove it can.
The Bristol-based deeptech firm closed the first tranche of its Series A, led by Mercia Ventures, with participation from Tees River, Daphni, Blast Club, and returning investors Speedinvest and Playfair. The raise brings Astral’s total funding to more than £28M.
“We are rewriting how we approach fusion and, in doing so, redefining what it means to be a fusion company. With this new funding, we can accelerate our ambition of building a profitable, impactful fusion business,” says Talmon Firestone, Astral’s CEO and co-founder.
A supply chain most people don’t know is broken
The radioisotopes used in nuclear medicine, the radioactive atoms that power cancer scans and emerging targeted therapies, are not manufactured like conventional drugs. They are produced by bombarding materials inside nuclear reactors, most of which are decades old and concentrated in a small number of countries. The UK currently produces almost none domestically.
The fragility of this supply chain became painfully visible in 2009 and 2010. In summer 2009, Canada’s Chalk River reactor and the Dutch High Flux Reactor at Petten were both offline simultaneously, causing shortages across Europe and North America. When Petten shut down again in February 2010 for further repairs to the cooling pipes, hospitals faced anticipated but serious shortfalls for months. The problem has not been structurally solved since.
Astral’s answer is a compact fusion reactor it calls a multi-state fusion, known as MSF, device, a design that combines different fusion states in a single unit to generate high-intensity neutron beams, the particles needed to irradiate target materials and produce isotopes.
Founded in 2021 by Firestone and Dr Tom Wallace-Smith, the startup has multiple reactors operating at Technology Readiness Level 9, meaning real-world deployment rather than lab testing. It has three commercial fusion facilities running and has signed research contracts worth more than £3M.
In partnership with McMaster University and Brazil’s Institute for Energy and Nuclear Research, Astral has been working to produce Actinium-225 and Lead-212, two isotopes increasingly used in targeted cancer therapies that have few reliable alternative sources. It plans to bring at least one to market by early 2027.
Why Berkeley and why now
With the new capital, Astral plans to run multiple next-generation reactors at full capacity by the end of 2026 at its new facility at the former Berkeley Power Station in Gloucestershire, a decommissioned nuclear site with existing grid connections, nuclear-grade infrastructure, and an established relationship with the Office for Nuclear Regulation.
The company aims to reach profitability within 2027 and grow its team from 23 to more than 40 people by the end of 2026. Nuclear physicist Dr Theresa Benyo, a NASA Laureate, recently joined as chief research officer, alongside chief scientist Dr Mahmoud Bakr, giving Astral scientific depth at a critical growth stage.
Astral is not the only company chasing the radioisotope gap. SHINE Technologies in the US has raised more than $1 billion in total funding, including a $240M round in February 2026, to produce medical isotopes using fusion-adjacent neutron technology, and currently operates one of the largest Lutetium-177 production facilities in North America.
Niowave, also US-based, uses electron accelerators for isotope production. Both are further along commercially in isotope supply, but neither operates in the UK market. Astral’s case to investors rests on its MSF technology producing a broader range of isotopes than single-purpose competitors, at a modular scale that could be replicated across sites.
Lee Lindley, who led the deal at Mercia Ventures, said the near-term commercial application was central to the firm’s conviction. “Astral’s technology has the potential to transform the manufacturing and supply of medical isotopes, which are vitally important for diagnostic and therapeutic purposes. Astral Systems is a perfect example of the bold ideas that Mercia likes to back,” he says.
According to Grand View Research, the global nuclear medicine market was valued at $17.77 billion in 2024 and is projected to reach $34.51 billion by 2030, growing at just over 10% a year, driven by an ageing population and rising demand for precision oncology.
Whether Astral can hit profitability in 2027 while scaling novel reactor production at a former power station is the question investors are now betting on, and the one that will determine whether fusion’s first commercial chapter is written in Bristol.
