Paper Notes #1: The Value and Cost of Fusion Neutrons

The Value and Cost of Fusion Neutrons

A D-T fusion reactor is, at its core, a neutron source. While electricity is one of the ultimate prizes, those neutrons can do a lot more than generating heat and driving a steam cycle. They can transmute materials into valuable isotopes, from medical radioisotopes like actinium-225 down to precious metals like gold. The revenue per neutron spans roughly ten orders of magnitude depending on what you make with it, and that range is the key insight of this paper.

We wanted a simple, rigorous way to ask: when does it actually pay to run a fusion device for its neutrons? So we introduced the levelized cost of a neutron, or LCON - the neutron analogue of levelized cost of energy (LCOE). Just as LCOE tells you the minimum electricity price for a power plant to break even, LCON tells you the minimum value you need to extract per neutron for your fusion system to be economically viable. It depends on the things you’d expect like plasma gain, capital intensity, availability, neutron flux, and it’s offset by whatever revenue you can pull in from co-produced electricity or transmutation products.

What falls out of this is something we call the “neutron ladder”: a staged, revenue-positive development pathway from today’s experiments to future power plants. Current fusion devices produce neutrons that are very expensive, but the most valuable neutron applications (like Ac-225 production) can tolerate high costs, meaning even early fusion systems can be economically productive if pointed at the right products. As the technology matures and LCON drops, you step down the ladder to progressively cheaper products, eventually reaching electricity at the bottom. The exciting takeaway is that fusion doesn’t have to wait for breakeven power plants to start generating real value: there’s a viable economic path that begins with the machines we’re already operating.