The Feed Materials Production Center, northwest of Cincinnati, processed uranium concentrates and uranium compounds recycled from other stages of nuclear weapons production, as well as some uranium ore and thorium. Particulate releases were primarily uranium (natural, depleted, and slightly enriched. In addition, two large silos containing radium-bearing residues were emission sources of radon and its decay products. The Fernald Dosimetry Reconstruction Project was undertaken to help the Centers for Disease Control and Prevention to evaluate the impact of the Feed Materials Production Center on the public from radionuclides released to the environment from 1951 through 1988. At this point in the study, the project has estimated the quantities of radioactive materials released to air, surface water, and in groundwater; developed the methodology to describe the environmental transport of the materials; developed mathematical models to calculate the resulting radiation doses; and evaluated environmental monitoring data to verify that the estimates of releases and transport are reasonable. Thorough review of historical records and extensive interaction with former and current employees and residents have been the foundation for reconstructing routine operations, documenting accidents, and evaluating unmonitored emission sources. The largest releases of uranium to air and water occurred in the 1950's and 1960's. Radon releases from the silos remained elevated through most of the 1970's. The quantity of uranium released to surface water was much less than that released to air. Best estimates of releases are reported as median values, with associated uncertainties calculated as an integral part of the estimates. Screening calculations showed that atmospheric pathways dominate the total dose from Feed Materials Production Center releases. Accordingly, the local meteorology, effluent particle size and chemical form, and wet and dry deposition, were particularly important in this study. The final goal of the project is the calculation of radiation doses to people living in the study domain, which is represented by a circle with radius of 10 km centered on the Feed Materials Production Center production area.
Agency for protectionof the general public. The calculations involved modeling the transport of radionuclidesfrom buried waste, to surface soil and subsurfacemedia, and eventuallyto members of the general public via air, ground water, and food chain pathways. Projectionsof doses were made for both offsite receptors and individuals intrudingonto the site after closure. In addition, uncertainty analyses were performed.Results of calculationsmade using nominal data indicate that the radiologicaldoses will be below appropriateradiologicalcriteria throughout operations and after closure of the facility.Recommendationswere made for future performanceassessment calculations. Three time periods of concern were addressed in this evaluation of the RWMC:I. The operational period, 1964 through 2089, during which radioactivewaste is actively disposed of at the facility. 2.The institutionalperiod, 2089 through 2189, which follows site clo_ure and during which periodic maintenance and monitoring activities are conducted. The facility is assumed to be stabilized but is still part of the INEL reservation and is fenced and patrolled. 3.The post-institutionalperiod, 2189 through 11975, during which the facility is no longer maintainedby the DOE and may be accessible to the public. iii DRAFT boundary at the location of maximum concentrationof airborne radionuclides in the transport medium of concern (i.e., air or ground water).The second type of receptor evaluated is an intruder. This hypotheticalreceptor is assumed to inadvertentlyintrude on the RWMC during the post-institutionalcontrol period. Two general kinds of scenarios were evaluated. The first is an agriculture scenario in which the receptor obtains half of his produce from farming at the RWMC. This individualalso drinks water from a well drilled at the edge of the waste. The second is an acute exposure scenario that includes a constructionscenario and a well-drillingscenario. In the construction scenario, the receptor is an individualwho is building a house at the RWMC and is exposed to contaminatedsoil while excavating the cellar. In the well-drilling scenario, the receptor is exposed to contaminateddrill cuttings that are deposited in a mud pit.Results of the monitoring, special studies, and modeling efforts to date indicate that the greatest potential for transport of radionuclides from the RWMC to offsite receptors (now and in the future) is via airborne transport of resuspended contaminatedsurface soil particles and ground water transport of radionuclidesleached from buried waste. For this reason, the performance assessmentonly addresses these two transport pathways.The exposure pathways evaluated include ingestion of food and water, inhalation of contaminatedairborne particulates,and external exposure to radionuclidesin air and soil. The agriculturalproducts consumed by the general public are contaminatedvia food chain transport of radionuclides deposited from air onto soil or plant surfaces. Projections of radionuclideconcentrationsin surface soil and subsurfacemedi...
Twenty-eight antibiotics were tested with the Limulus amoebocyte lysate assay to determine their non-inhibitory concentrations (NICs). The Limulus amoebocyte lysate assay was found to be a valid test for most of the antibiotics tested; the NICs were found to be greater than the minimum valid test concentrations. Borderline results were obtained with cefamandole nafate and neomycin sulfate. Polymyxin B and colistimethate contained too much endotoxin to permit determination of NICs. The NIC of tetracycline hydrochloride was dependent on the initial concentration of antibiotic. This dependence was most likely caused by the amount of base required to adjust the pH before testing.
This paper describes the application of simple linear models to help design environmental monitoring systems. This process involves five steps: (1) The derivation of a schematic of the identified pollutant's transport and fate. (2) The derivation of the equation in the schematic. (3) Estimation of input data and numerical solution. (4) Comparison with initial field data. (5) Design of a monitoring system.Two examples of how this system was applied under field conditions are given. Advantages of this approach are: (1) It forces a consideration of the system as a whole rather than a series of distinct environmental components. (2) It forces a consideration of the physical-chemical and biological factors effecting pollutant transport in the system. (3) It sets up an analytical procedure for data analysis at the time the monitoring system is designed. (4) It helps show the functional relationship between pollutant levels in different environmental media. (5) It identifies points where sampling design could be changed to provide for a more efficient monitoring system. (6) It identifies gaps in our knowledge base.
The growth rate of a eukaryotic population dividing at a constant rate can be estimated from the equation, tm/g In 2 = in (1 + R), in which tm is the time required for mitosis, g is the generation time, and R is the fraction of cells undergoing mitosis. Values for tm and R can be determined by direct microscope examination of the population. The validity of the derived equation has been checked with an exponentially growing culture of a prokaryote, Escherichia coli, in which chloramphenicol was administered to inhibit protein synthesis. Cells having enough protein completed the division process whereas the rest of the population was inhibited. From the plot of the growth curve before and after administration of chloramphenicol, tm and R were estimated. The calculated and actual growth rates were almost identical.
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