Proliferation Risks of Fusion Energy: Clandestine Production, Covert Production, and Breakout

Nuclear proliferation risks from fusion associated with access to weapon-usable material can be divided into three main categories: 1) clandestine production of fissile material in an undeclared facility, 2) covert production of such material in a declared and safeguarded facility, and 3) use of a declared facility in a breakout scenario, in which a state begins production of fissile material without concealing the effort. In this paper we address each of these categories of risk from fusion. For each case, we find that the proliferation risk from fusion systems can be much lower than the equivalent risk from fission systems, if commercial fusion systems are designed to accommodate appropriate safeguards.