T.J. Tarnowsky
Los Alamos National Laboratory,
United States
Keywords: tritium, fusion energy, critical materials
Summary:
On-Ramping the Fusion Economy with Kilogram Quantities of Commercial Tritium Terence J. Tarnowsky, Ph.D. Los Alamos National Laboratory LA-UR-24-33273 For many reasons, the US has no commercial, domestic tritium production capabilities. The value (2024 $) of commercial tritium is ~$33,000,000/kg [1]. A 1 GWth D-T fusion energy plant full power year (FPY) will need more than 55 kgs of tritium/year. These power plants are hoping to breed tritium during operation and the required Tritium Breeding Ratio (TBR) to feed back to the fusion reactor must be > 1.0 (ideally, 1.1 – 1.2). Small uncertainties (~1%) in system TBRs can still lead to changes of over +/- 500 g = per FPY at 1 GWth [2]. Starting a fusion plant with no tritium (using D-D reactions to breed tritium) is not economically viable [3,4]. Currently, commercial tritium supplies are produced in heavy-water reactors like the 600 MW, Canada Deuterium Uranium (CANDU) at rates of 0.1 kg / yr. We propose to investigate the design, development, performance requirements and cost of an accelerator-driven system (ADS) using molten salt (MS) technology as the working material for transmuting used reactor fuel and producing a supply of commercial tritium. Recycling and transmuting used nuclear fuel (UNF) in an ADS satisfies multiple needs: 1) Long-lived transuranic material is destroyed, thereby improving the acceptance of a UNF repository, 2) Energy is produced by fission (offsetting the power used by the accelerator), and 3) The system is operated in a sub-critical configuration, which improves safety while minimizing criticality constraints. This ADS+MS concept is well-suited for a commercial tritium production mission and the US Department of Energy has the requisite experience with handling, processing, storing, and transporting the products. An ADS+MS facility can achieve TBRs > 20 with current technology, provide kg quantities of tritium annually, decrease the overall cost of construction and operations at a fusion power plant, and lower proliferation risks. References: 1. Clery, D., "Out of Gas". Science, 1372-1376, 2022. 2. Khater, H., “Review of Challenges to Achieving Tritium Self-sufficiency”. Workshop for Applied Nuclear Data Activities (WANDA 2024)” February 27, 2024. 3. Kovari, M., et al., "Tritium resources available for fusion reactors", Nucl. Fusion 58 (2018) 026010, 2018. 4. Siccinio, M., et al. " Feasibility of D-D start-up under realistic technological assumptions for EU-DEMO." Fusion Engineering and Design, 171, 112554, 2021.