D-T Fusion Reactors Could Produce 2 Metric Tons of Gold Annually Per Gigawatt, Study Claims

A novel proposal suggests that deuterium-tritium (D-T) nuclear fusion reactors could unexpectedly produce significant quantities of gold as a valuable byproduct, potentially doubling their economic output. This innovative concept involves integrating Mercury-198 into the reactor's breeding blanket, a component typically designed for tritium fuel production. The method, detailed in a recent paper by Marathon Fusion, aims to enhance the financial viability of fusion energy by leveraging fast neutrons to transmute mercury into gold.

The process centers on bombarding the stable isotope Mercury-198 (198Hg) with high-energy neutrons generated by D-T fusion reactions. This interaction triggers an (n, 2n) reaction, converting 198Hg into unstable Mercury-197 (197Hg), which then rapidly decays into stable Gold-197 (197Au) within approximately 64 hours. This transmutation occurs within a specialized breeding blanket, a layer surrounding the plasma chamber in a tokamak reactor.

Simulations by Marathon Fusion project that a gigawatt-scale thermal fusion reactor could yield up to 2 metric tons of gold annually, valued at over $550 million at current prices. This substantial revenue stream, generated without compromising energy output or tritium breeding, could significantly subsidize the deployment of fusion power plants. The company believes this "scalable chrysopoeia" could dramatically enhance the economic attractiveness of fusion energy.

While promising, the concept faces several practical considerations, including the need for a cooling period of up to 17.7 years for the produced gold due to small amounts of other radioactive isotopes. The proposed method also requires an initial inventory of enriched mercury and reactor materials capable of handling the process. The paper, authored by Adam Rutkowski and Kyle Schiller, is currently a preprint and has not yet undergone peer review.

The potential for such a valuable byproduct was highlighted by Artem Andreenko, who stated in a tweet, > "One of the surprising by-products of D-T fusion could be gold if the breeding blanket is composed of Lithium and Mercury-198, improving overall economic value of the reactor output." This sentiment aligns with Marathon Fusion's goal of enhancing fusion's economic appeal and accelerating its widespread adoption.