PANEL ON NONPROLIFERATION AND SAFEGUARDS ASPECTS OF FUSION (SOME VISUALS) Alexander Glaser Princeton University 66th Annual INMM Meeting Washington, DC, August, 2025 Revision 1 Source: Universal Pictures NUCLEAR FUSION IN 2025 For many decades, largely a government-led effort, but fusion R&D is increasingly conducted by startups and/or involves public-private partnerships: - At least 45 companies are seeking to commercialize fusion energy - More than $7 billion in funding - More than 1,000 scientists and engineers recruited per year Most concepts pursued for energy applications are based on magnetic confinement fusion and rely on the DT fusion reaction: D + T → 4He + n + 17.6 MeV In-situ tritium breeding, primarily via: n + 6Li → 4He + T + 4.8 MeV Source: The Global Fusion Industry in 2024, Fusion Companies Survey by the Fusion Industry Association, Fusion Industry Association, 2024 There is enough nuclear explosive material in the world to make over 200,000 nuclear weapons - 1240 tons of highly enriched uranium (HEU) Each block corresponds to 12 kg of HEU, the amount necessary to make a fission bomb; about 100,000 bombs-worth total - 565 tons of separated plutonium Each block corresponds to 4 kg of plutonium, the amount necessary to make a fission bomb; about 140,000 bombs-worth total Graphic/concept by Alex Wellerstein and Tamara Patton Inventory estimates from fissilematerials.org Status as of beginning of 2024 FISSILE MATERIAL PRODUCTION POTENTIAL OF NUCLEAR FUSION REACTORS FUSION REACTORS AS NEUTRON-RICH ENVIRONMENTS Standard operation of a fusion reactor does not involve nuclear materials, which offers significant nonproliferation benefits compared to nuclear fission reactors; the presence of intense neutron fluxes provides an environment, however, that could be used for covert production of fissile materials. HOW MUCH FISSILE MATERIAL COULD POSSIBLY BE PRODUCED? Previous analyses have shown that a commercial-scale reactor with a fusion power of 1500 MW (600–750 MWe) could be used to make on the order of 10 kg of Pu-239 or U-233 per week. Source: iter.org (top); A. Glaser and R. J. Goldston, Proliferation Risks of Fusion Energy: Clandestine Production, Covert Production, and Breakout, Nuclear Fusion, 52 (4), 2012 PLUTONIUM BUILDUP IN THE BLANKET (1500 MW OF FUSION POWER; 25 TRISO PARTICLES/CC IN BREEDING CHANNELS) - In the reference scenario, about one significant quantity of plutonium builds up in one month. - Depending on the blanket type (Molten Salt [Flibe] vs Dual Coolant Lithium Lead [DCLL]), 60–85 MW of fission power are generated throughout the process. - Note that more aggressive production scenarios could deliver 8–10 kilograms of plutonium per week. References: - A. Glaser, R. J. Goldston, P. Huber, Detectability of Covert Fissile Material Production in Nuclear Fusion Reactors via Antineutrino Emissions, August 2025, arxiv.org/abs/2508.16358 - A. Glaser and R. J. Goldston, Proliferation Risks of Fusion Energy: Clandestine Production, Covert Production, and Breakout, Nuclear Fusion, 52 (4), 2012 ADDRESSING DUAL-USE ASPECTS OF FUSION: A PROACTIVE APPROACH FUSION TECHNOLOGY - Consider (and prioritize) system configurations and materials that make military use difficult, especially with regard to fissile material production (and tritium diversion). - Design reactors and other test facilities with inspections and verifiability in mind. POLICY & REGULATION FOR NUCLEAR FUSION - Acknowledge that nuclear fusion reactors can raise security (and safety) concerns. - Involve, at an early stage, the International Atomic Energy Agency on how to monitor fusion reactors. Source: Max Planck Institute for Plasma Physics (top) and iaea.org (bottom)