RESUMEN
Radiocesium is one of the more prevalent radionuclides in the environment as a result of weapons production-related atomic projects in the USA and the former Soviet Union. Radiocesium discharges during the 1950s account for a large fraction of the historical releases from US weapons production facilities. Releases of radiocesium to terrestrial and aquatic ecosystems during the early years of nuclear weapons production provided the opportunity to conduct multidisciplinary studies on the transport mechanisms of this potentially hazardous radionuclide. The major US Department of Energy facilities (Oak Ridge Reservation in Tennessee, Hanford Site near Richland, Washington, and Savannah River Site near Aiken, South Carolina, USA) are located in regions of the country that have different geographical characteristics. The facility siting provided diverse backgrounds for the development of an understanding of environmental factors contributing to the fate and transport of radiocesium. In this paper, we summarize the significant environmental releases of radiocesium in the early years of weapons production and then discuss the historically significant transport mechanisms for 137Cs at the three facilities that were part of the US nuclear weapons complex.
Asunto(s)
Radioisótopos de Cesio/historia , Guerra Nuclear/historia , Residuos Radiactivos , Animales , Radioisótopos de Cesio/análisis , Ambiente , Exposición a Riesgos Ambientales , Historia del Siglo XX , Monitoreo de Radiación , Liberación de Radiactividad Peligrosa/estadística & datos numéricos , Residuos Radiactivos/análisis , Residuos Radiactivos/estadística & datos numéricos , South Carolina , Tennessee , WashingtónRESUMEN
In 1989, Pacific Northwest National Laboratory developed a program, for the U.S. Department of Energy, to involve local citizens in environmental surveillance at the Hanford Site. The Community-Operated Environmental Surveillance Program was patterned after similar community-involvement efforts at the Nevada Test Site and the Three Mile Island nuclear facility. Its purpose is to increase the flow of information to the public, thereby enhancing the public's awareness and understanding of surveillance activities. The program consists of two components: radiological air monitoring at nine offsite locations and agricultural product sampling at selected locations near the site. At each air-monitoring station, two local school teachers collect air particulate samples and operate equipment to monitor ambient radiation levels. Atmospheric tritium samples (as water vapor) are also collected at some locations. Four of the air-monitoring stations include large, colorful informational displays for public viewing. These displays provide details on station equipment, sample types, and sampling purposes. Instruments in the displays also monitor, record, and show real-time ambient radiation readings (measured with a pressurized ionization chamber) and meteorological conditions. Agricultural products, grown primarily by middle-school-aged students, are obtained from areas downwind of the site. Following analysis of these samples, environmental surveillance staff visit the schools to discuss the results with the students and their teachers. The data collected by these air and agricultural sampling efforts are summarized with other routinely collected sitewide surveillance data and reported annually in the Hanford Site environmental report.
Asunto(s)
Participación de la Comunidad , Monitoreo de Radiación , Protección Radiológica , Contaminación Radiactiva del Aire/análisis , Contaminación Radiactiva del Aire/prevención & control , Agencias Gubernamentales , Humanos , Conceptos Meteorológicos , Estados Unidos , WashingtónRESUMEN
This review is concerned with exposure risk and the environmental pathways models used for predictive assessment of radiation dose. Exposure factors, the adequacy of available data, and the model subcomponents are critically reviewed from the standpoint of absolute error propagation. Although the models are inherently capable of better absolute accuracy, a calculated dose is usually overestimated by from two to six orders of magnitude, in practice. The principal reason for so large an error lies in using "generic" concentration ratios in situations where site specific data are needed. Major opinion of the model makers suggests a number midway between these extremes, with only a small likelihood of ever underestimating the radiation dose. Detailed evaluations are made of source considerations influencing dose (i.e., physical and chemical status of released material); dispersal mechanisms (atmospheric, hydrologic and biotic vector transport); mobilization and uptake mechanisms (i.e., chemical and other factors affecting the biological availability of radioelements); and critical pathways. Examples are shown of confounding in food-chain pathways, due to uncritical application of concentration ratios. Current thoughts of replacing the critical pathways approach to calculating dose with comprehensive model calculations are also shown to be ill-advised, given present limitations in the comprehensive data base. The pathways models may also require improved parametrization, as they are not at present structured adequately to lend themselves to validation. The extremely wide errors associated with predicting exposure stand in striking contrast to the error range associated with the extrapolation of animal effects data to the human being.