关键词：大气；大气污染；放射性元素
摘 要：Department of Energy Technical Standard 1027 categorizes DOE facilities by the off-site radiation dose consequence resulting from a design basis accident, using this postulated event to determine if a facility is considered to be a radiological facility or a nuclear facility. The accident scenario used in this type of assessment is an uncontrolled release of the entire radioactive material inventory within the facility, using standard assumptions on air plume dispersion, uptake of radionuclides, distance to receptor, and other parameters that are consistent for all DOE facilities. Thus, the primary input on determining off-site dose in this assessment is the quantity of radioactive material within the facility. Controlling and tracking this inventory becomes the principal method of managing a facility's hazard categorization. A radiological facility is considered to pose very little risk to the public, while nuclear facilities have increasing amounts of controls required in their processes due to the increasing hazards of their operations and increasing radioactive material inventories. The dose threshold between a radiological facility and a Hazard Category 3 nuclear facility is a 10 rem dose to an individual located 30 meters from the facility. Prior to 2011, the amount of radioactive material inventory that would correspond to this 10 rem dose was 8.4 grams of plutonium-239 or equivalent material. Facilities track their radioactive material inventory relative to the threshold quantities of nuclides used in that facility, using a gsum of fractionsh method.