Chapter 9: Glossary
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Glossary 9-1 Depleted UF6 PEIS 9 GLOSSARY accident: An unplanned sequence of events accident risk: Risk based on both the severity resulting in undesirable consequences, such as of an accident (consequence) and the probability the release of radioactive or hazardous material that the accident will occur. High-consequence to the environment. accidents that are unlikely to occur (low probability) may pose a low overall risk. For accident consequence assessment: An assess- purposes of comparison, accident risk is typically ment of the impacts following the occurrence of calculated by multiplying the accident an accident, independent of the probability of that consequence (e.g., dose or expected fatalities) by accident. The PEIS provides estimates of the the accident probability. consequences of a large number of possible accidents, ranging from those with low proba- accident risk assessment: An assessment that bility (rare) to those with relatively high proba- considers the probabilities and consequences of bility (frequent). a range of possible accidents, including low- probability accidents that have high conse- accident frequency: The likelihood that a quences and high-probability accidents that have specific accident will occur, that is, the proba- low consequences. The overall risk associated bility of occurrence. If an accident is esti- with an accident is generally estimated by mated to happen once every 50 years, the multiplying the accident consequence by the accident frequency is generally reported as probability of occurrence. 0.02 per year (1 occurrence divided by 50 years = 0.02 occurrences per year). For the PEIS, accident source term: The amount of radio- accident frequencies were grouped as follows: active or hazardous material released to the environment in dispersible form following an • I, likely (L) — The average frequency of accident. occurrence is estimated to be greater than or equal to 1 in 100 years. adsorption: Process in which solid surfaces attract and retain a layer of ions from a water • II, unlikely (U) — The average frequency solution. of occurrence is estimated to be 1 in 100 to 1 in 10,000 years. advection: The process by which material is transported by the bulk motion of flowing water. • III, extremely unlikely (EU) — The average frequency of occurrence is esti- air quality: Measure of the health-related and mated to be 1 in 10,000 to 1 in 1 million visual characteristics of the air, often derived years. from quantitative measurements of the concen- trations of specific injurious or contaminating • IV, incredible (I) — The average fre- substances. Air quality standards are the quency of occurrence is estimated to be prescribed level of constituents in the outside air less than 1 in 1 million years. that cannot be exceeded during a specific time in a specified area. Glossary 9-2 Depleted UF6 PEIS Air Quality Control Region (AQCR): An workforce and the public) and releases of interstate or intrastate area designated by the radioactive material to the environment as low as U.S. Environmental Protection Agency for the social, technical, economic, practical, and public attainment and maintenance of National Ambient policy considerations permit. ALARA is not a Air Quality Standards. dose limit; it is a practice that has as its objective the attainment of dose levels as far below ALARA: see as low as reasonably achievable. applicable limits as possible. alpha particle ("): A positively charged Atomic Energy Act of 1954: The Act that, particle consisting of two protons and two along with other related legislation, provided the neutrons that is emitted during radioactive decay Atomic Energy Commission (a predecessor of from the nucleus of certain nuclides. It is the least the U.S. Department of Energy) with authority to penetrating of the three common types of develop generally applicable standards for radiation (alpha, beta, and gamma). protecting the environment from radioactive materials. ambient air: The surrounding atmosphere as it exists around people, plants, and structures. attainment area: An area considered to have air quality as good as or better than the National American Indian Religious Freedom Act of Ambient Air Quality standards as defined in the 1978: The Act that established national policy to Clean Air Act. An area may be an attainment protect and preserve for Native Americans their area for one pollutant and a nonattainment area inherent right of freedom to believe, express, and for others (see also nonattainment area). exercise their traditional religions, including the rights of access to religious sites, use and Bald and Golden Eagle Protection Act, as possession of sacred objects, and freedom to amended: The Act making it unlawful to take, worship through traditional ceremonies and rites. pursue, molest, or disturb bald (American) and golden eagles, their nests, or their eggs anywhere AQCR: see Air Quality Control Region. in the United States. aquifer: A saturated subsurface geologic forma- beta particle ($): An elementary particle tion that can transmit significant quantities of emitted from a nucleus during radioactive decay; water. it is negatively or positively charged, identical in mass to an electron, and in most cases easily Archaeological and Historic Preservation Act: stopped, as by a thin sheet of metal or plastic. Act directed at the preservation of historic and archaeological data that would otherwise be lost biota: The plant and animal life of a region. as a result of federal construction. It authorizes the U.S. Department of the Interior to undertake blending: The mixing of two quantities of recovery, protection, and preservation of archae- uranium with different levels of enrichment to ological and historic data. produce uranium enriched to a level suitable for manufacture into a fuel. Depleted uranium can be as low as reasonably achievable (ALARA): blended with highly enriched uranium to produce An approach to control or manage radiation nuclear reactor fuel. exposures (both individual and collective to the Glossary 9-3 Depleted UF6 PEIS bounding: In the case of accident analysis, graphic dimensions of census tracts vary widely, bounding is a condition, consequence, or risk that depending on population settlement density. provides an upper limit that is not exceeded by Census tracts do not cross county borders. other conditions, consequences, or risks. This term is also used to identify conservative Clean Air Act: The Act that mandates the assumptions that will likely overestimate actual issuance and enforcement of air pollution control risks or consequences. standards for stationary sources and motor vehicles. breach: A general term referring to a hole in a cylinder or container. A breach may be caused by Clean Air Act Amendments of 1990: An Act corrosion or by mechanical forces, such as those that expanded the enforcement powers of the caused by a drop or contact with handling U.S. Environmental Protection Agency and equipment. added restrictions on air toxins, ozone-depleting chemicals, stationary and mobile emissions cancer: A group of diseases characterized by sources, and emissions implicated in acid rain uncontrolled cellular growth. Increased incidence and global warming. of cancer can be caused by exposure to radiation. Clean Water Act of 1972, 1987: The Act that candidate species: Plant or animal species that regulates the discharge of pollutants from a point are not yet officially listed as threatened or source into navigable waters of the United States endangered but are undergoing status review by in compliance with a National Pollution Dis- the U.S. Fish and Wildlife Service. These species charge Elimination System permit. Also are candidates for possible addition to the list of regulates discharges to or dredging of wetlands. threatened and endangered species. Code of Federal Regulations (CFR): The carbon monoxide (CO): A colorless, odorless codified form in which all federal regulations in gas that is toxic if breathed in high concentration force are published. over a period of time. Carbon monoxide is one of six criteria air pollutants specified under Title I of collective dose: Summation of individual the Clean Air Act. radiation doses received by all those exposed to the source or event being considered. The collec- cascade: The process system that is used to tive radiation dose received by a population separate the isotopic streams of uranium-235 and group is usually measured in units of person-rem. uranium-238 in gaseous diffusion plants. collective population risk: A measure of cask: A heavily shielded, typically robust con- possible loss in a group of people that takes into tainer for shipping or storing spent nuclear fuel. account the probability that the hazard will cause Spent nuclear fuel casks are usually cylindrical harm and the consequences of that event. The containers with radiation shielding provided by collective population risk does not express the steel, lead, concrete, or depleted uranium. risk to specific individual members of the population. census tract: An area usually containing between 2,500 and 8,000 persons that is used for committed effective dose equivalent: The sum organizing and monitoring census data. The geo- of the committed dose equivalents to various Glossary 9-4 Depleted UF6 PEIS tissues of the body, each multiplied by its weight- reasonably foreseeable future actions regardless ing factor. It does not include contributions from of what agency (federal or nonfederal), private external doses. Committed