Nuclear fusion start-up claims to have cracked alchemy

Telegraph

22-07-2025

Over thousands of years, it has captivated thinkers such as Newton, the English physicist who developed the mathematical law of universal gravitation in the late 17th century.
Many dreamed of creating a 'philosopher's stone' that would be used as a catalyst for transmuting base metals such as lead into gold.
Marathon's idea relies on substituting materials used in the well-understood process of nuclear fusion instead.
Fusion takes place when two isotopes of hydrogen, deuterium and tritium, are forced together to create helium, releasing high-energy subatomic particles called neutrons.
It is accomplished by heating the deuterium and tritium atoms to extreme temperatures of more than 100 million degrees Celsius and then confining them into a tight space so that they collide.
The process becomes self-sustaining when helium atoms collide with the fuel particles, transferring their energy and ensuring the reaction keeps going.
But fusion reactors typically contain other materials, including isotopes of beryllium, lead, or lithium, to ensure there is continuously enough tritium in the mix.
These are known as 'multipliers' because when they are hit by a neutron, they release two neutrons in their place. These extra neutrons then react with lithium to produce tritium.
Radical transformation
Marathon's method uses mercury-198, a common form of mercury, as a multiplier. When hit by a neutron, these atoms change into a less stable form called mercury-197.
Over a few days, those atoms then naturally break down into a stable form of gold.
Marathon claims this means the fusion process can be used to generate supplies of gold as a byproduct, 'without any compromise to fuel self-sufficiency or power output'.
Using the new approach, the company says a fusion power plant with a capacity of about one gigawatt could generate 5,000 kilograms of gold per year.
The gold produced by the reaction is stable, but could contain some radioactive gold isotopes, potentially meaning it must be stored for up to 18 years, according to the company.
The start-up added: 'Marathon's techno-economic modelling suggests that fusion plants could create as much economic value from gold production as they do from electricity production, potentially doubling the value of these facilities, radically transforming the economics of fusion and of energy more broadly.'
Beyond gold, it also claimed the transmutation process could be used for making precious metals such as palladium, synthesising medical isotopes, or producing materials for 'nuclear batteries'.
Marathon was founded by Adam Rutkowski, a former engineer at Elon Musk's rocket company, SpaceX, and Kyle Schiller, who was a fellow at ex-Google boss Eric Schmidt