Researchers have proposed a method to leverage the high-energy neutron flux from deuterium-tritium (D-T) fusion power plants for the large-scale production of alpha-emitting isotopes used in nuclear batteries. A new preprint posted to arXiv outlines how a single gigawatt-scale fusion plant could produce these radioisotope power sources at a rate of tons per year, a significant increase over the current global supply of Plutonium-238, which is measured in kilograms per year. The study uses OpenMC, a Monte Carlo neutron transport code, to simulate transmutation channels within a tokamak blanket, identifying pathways to generate both established and novel battery fuels. Source: arXiv

The analysis focuses on the 14 MeV neutrons characteristic of the D-T fuel cycle, which can initiate neutron-induced reactions unavailable in fission reactors. The simulations predict that for each gigawatt-year of fusion operation, a plant could produce between 11 and 57 kg of Plutonium-236. This isotope's decay chain releases 18 gigajoules per gram over a century, ending at stable Lead-208. The process would also yield up to 5.2 tonnes of the conventional battery fuel Plutonium-238 as a co-product. These production volumes represent a potential paradigm shift for applications requiring long-duration, reliable power sources in remote or inaccessible environments. Source: arXiv

The simulations predict that for each gigawatt-year of fusion operation, a plant could produce between 11 and 57 kg of Plutonium-236.

Beyond plutonium isotopes, the paper identifies scalable production routes for other valuable alpha emitters. By irradiating thorium in the blanket, up to 1.4 tonnes of Protactinium-231 can be bred annually. This Pa-231 can then serve as a feedstock for further transmutation. With a dedicated Pa-231 channel, the same fusion plant could generate approximately 15 tonnes of Uranium-232 or 122 kg of Lead-210 per GW-year. The simulations also show a pathway to produce Actinium-227 at a rate of 21 grams per year for every tonne of Pa-231 feedstock present. These alternative isotopes offer different power densities and half-lives, expanding the design space for nuclear batteries. Source: arXiv

The study also proposes a method for upgrading existing radioisotope stockpiles. Neutron capture on Americium-241, a common nuclear waste product, can transmute it into a blend of Curium-242, Americium-242m, and Plutonium-238. According to the preprint, this resulting isotopic mixture exhibits a power density up to 10 times higher than the original Am-241, making it a more potent fuel for compact power systems. This illustrates a dual benefit of future fusion plants: generating clean electricity while simultaneously creating high-value materials and potentially mitigating certain classes of nuclear waste. This co-generation model could significantly alter the economic calculations for commercial fusion energy. Source: arXiv

While the findings are based on simulations, they present a compelling secondary application for first-generation D-T fusion power plants. The economic and strategic value of a domestic, high-volume supply of alpha emitters for space exploration, defense, and industrial applications could provide an additional revenue stream for plant operators. The next steps would involve experimental validation of the simulated neutron cross-sections and yields, followed by detailed engineering studies for integrating these transmutation channels into future power plant and tritium breeding blanket designs. The practical implementation will depend heavily on materials science, target fabrication, and chemical separation technologies. Source: arXiv