Review of Fissile Material Exemptions and General Licenses in 10 CFR Part 71

摘要

Title 10 of the United States (US) Code of Federal Regulations (CFR), Part 71, Packaging and Transportation of Radioactive Material includes requirements for the transport of fissile material in packages. These regulations provide requirements for packaging that is certified by the US Nuclear Regulatory Commission (NRC) to transport fissile material, but the regulations also include provisions that allow for shipment of fissile material in packages that are not required to be certified by the NRC. These provisions include criteria for exemptions from classification as fissile material (10 CFR 71.15) and permit general licenses for limited quantities of fissile material and plutonium-beryllium special form sources (10 CFR71.22 and 10 CFR71.23, respectively). These regulations were revised by NRC as part of a broad rulemaking effort in 2004. These regulations are used frequently for a wide-variety of fissile material shipping operations and shippers must interpret the regulations for particular shipping situations. The quantity of fissile material that presents a criticality safety risk depends on the other materials in the system that might absorb neutrons emitted from fission or moderate (slow) those neutrons to lower energies where the probability of them creating an additional fission is highest. Besides the absorption and moderation of neutrons, other parameters that must be considered to ensure criticality safety are: the mass, concentration, or isotopic distribution of the fissile material; and the system geometry and neutron reflection of the package from surrounding materials. These parameters were carefully considered in developing the requirements for the exemptions from the classification of fissile material and the requirements for general licenses for fissile material. This paper will review the technical basis, intent, and anticipated usage of each of the fissile material exemption and general license provisions. Additionally, this paper will discuss the recent regulatory history of the Part 71 fissile material exemptions and general licenses, including the 2015 rulemaking effort. Finally, this paper will outline an upcoming NUREG/CR document regarding the fissile material exemptions and general licenses, and discuss recommendations that are being formulated for potential future revisions to the regulations.