Assessment of Challenges for Tritium Accountancy and Control in Fusion Energy Systems

The D-T fusion reactor energy systems are expected to have large (kg level) inventory of tritium inprocess for moderate-to-large (up to 500 MWth) power plants. Accountancy of tritium in these plants is expected be established for several needs including systems efficiencies; radiological safety; safety basis accident scenarios; and environmental release. In addition, because tritium with deuterium can be used to boost the yield of nuclear weapons, the question has arisen as to whether the same or similar safeguards’ controls used to manage inventories of special nuclear material (SNM) against theft or diversion should be applied to fusion tritium inventories. Although until 2011 regarded as a SNM by the U.S. Department of Energy (DOE), at present tritium is categorized as an “other nuclear material” for Nuclear Material Control and Accountability (NMC&A) program purposes per DOE-STD-1194-2019 as driven by DOE Order 474.2 for NMC&A. Neither the U.S. Nuclear Regulatory Commission (NRC) nor the International Atomic Energy Agency (IAEA) consider tritium as a SNM. This paper outlines the challenges for tritium accountancy in generic fusion energy systems and discusses the practicality of establishing a regulatory framework for safeguards controls.