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Introduction
Published in Michael J. Kennish, Ecology of Estuaries: Anthropogenic Effects, 2019
The input of radioactivity in estuaries and oceans is treated in Chapter 6. Radionuclides found in estuaries originate from naturally occurring terrigenous and cosmic sources. Nuclear explosions, power and propulsion reactors, as well as wastes from hospitals, research laboratories, and industries, represent sources of artificial radioactivity that have entered estuaries. Since 1944, a significant quantity of radioactive wastes accumulating in estuarine and marine systems have been derived from nuclear weapons testing and power productions. Fallout from nuclear weapons testing spread low concentrations of radioactivity across the surface waters of the marine biosphere between 1946 and 1980. The amounts and types of radioactive wastes generated in power productions are primarily a function of the nuclear fuel cycle employed. A typical nuclear fuel cycle consists of uranium mining, milling, conversion, uranium enrichment, nuclear fuel fabrication, irradiation of fuel elements in a nuclear reactor, and the reprocessing or disposal of spent fuel. Accidents, such as the loss of nuclear submarines (e.g., the USS Tresher in 1963 and the USS Scorpion in 1968) and airborne nuclear weapons contribute to anthropogenic releases of radionuclides to the marine environment. One of the primary concerns of radioactivity in estuarine and marine environments, similar to heavy metals, is their uptake by organisms and transference through food chains to man.
Air, Noise, and Radiation
Published in Gary S. Moore, Kathleen A. Bell, Living with the Earth, 2018
Gary S. Moore, Kathleen A. Bell
Most attention is focused on the nuclear power plants, due to their perceived threat. Nuclear power production involves a number of steps, referred to as the nuclear fuel cycle. These steps include mining the uranium, crushing and processing or milling the uranium, converting yellowcake to gaseous uranium hexafluoride, and enriching uranium to increase the concentration of the desired isotope from its original concentration.
Radioactive wastes and the public
Published in R.J. Pentreath, Nuclear Power, Man and the Environment, 2019
As to be expected, the more recent recommendations of the ICRP (No. 26) will alter, to some extent, the description which has been given in this chapter of the methods used to regulate the exposure of the general public to radionuclides via environmental materials. There will be changes in terminology: for example it is recommended that derived limits be set in defined models which relate either directly to dose limits or to secondary standards. More important, however, is the application of the change in ICRP philosophy. There are already differences in the application of ICRP guidelines at a national level. Having adopted the ICRP dose equivalent limits as the appropriate standards, some countries, such as the United Kingdom, have then made decisions on what is ‘as low as reasonably achievable’ for individual sites. Other countries, whilst again accepting the ICRP recommendations, have published ‘standards’ which, although specific to a particular situation, incorporate a general judgement on what is ‘as low as reasonably achievable’. There are also national differences resulting from the methods of legislation. For example, in the USA the Environmental Protection Agency (EPA) issues, at a federal level, generalized ‘standards’ for most of the different stages in the nuclear fuel cycle; and the Nuclear Regulatory Commission (NRC), which actually licenses the nuclear installations, issues guidelines on such matters as radioactive effluents that are specific for individual reactors. These overall guidelines may then be further modified locally by authorities which are involved at the State, rather than the Federal, level of government.
Demand-Driven Deployment Capabilities in Cyclus , a Fuel Cycle Simulator
Published in Nuclear Technology, 2021
Gwendolyn J. Chee, Roberto E. Fairhurst Agosta, Jin Whan Bae, Robert R. Flanagan, Anthony M. Scopatz, Kathryn D. Huff
The nuclear fuel cycle represents the nuclear fuel life cycle from initial extraction through processing to its use in reactors, and eventually, final disposal. This complex system of facilities and mass flows collectively provide nuclear energy in the form of electricity.1 Nuclear fuel cycle simulator tools were introduced to investigate nuclear fuel cycle dynamics at a local and global level. These simulators track the flow of materials through the nuclear fuel cycle, from enrichment to final disposal of the fuel, while also accounting for decay and transmutation of isotopes. The impacts are evaluated in the form of metrics, which are quantitative measures of performance.2 These metrics are calculated from mass balances and facility operation histories calculated by a fuel cycle simulator.2 By evaluating the performance metrics of different fuel cycles, we gain an understanding of how each facility’s parameters and technology choices impact the system’s performance. Therefore, these results can be used to guide research efforts, advise future design choices, and provide decision makers with a transparent tool for evaluating fuel cycle options to inform policy decisions.1