Aquatic Transport

Regulatory Guide 1.113 provides procedures for estimating the aquatic transport of accidental nd routine releases from nuclear reactors. Because these methods are complex and have not been included in PSAs, they are not discussed. 

The analysis of the consequences of nuclear accidents began with physical concepts of core melt, discussed the mathematical and code models of radionuclide release and transport within the plant to its release into the environment, models for atmospheric transport and the calculation of health effects in humans. After the probabilities and consequences of the accidents have been determined, they must be assembled and the results studied and presented to convey the meanings. 

Suppose an interstate highway passes 1 km perpendicular distance from a nuclear power plant control room air intake on which 10 trucks/day pass carrying 10 tons bf chlorine each. Assume the probability of truck accident is constant at l.OE-8/mi, but if an accident occurs, the full cargo is released and the chlorine flashes to a gas. Assume that the winds are isotropically distributed with mean values of 5 mph and Pasquill F stability class. What is the probability of exceeding Regulatory Guide 1-78 criteria for chlorine of 45 mg/m (15 ppm). 

How long can you remain in a very large flat field that is contaminated with radioactivity at a density of 1 curie m emitting gamma rays of 0.6 MeV mean energy before you exceed lOCFRlOO limits for whole body Assume the receptor is at 1 m. 

What whole body dose will you get from a 100 megacurie puff release passing at a perpendicular distance of 1 km traveling in a straight line at 3 mph  

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Webster, G.R.B., Muldrew, D.H., Graham, J.J., Sama, L.P., Muir, D.C.G. (1986) Dissolved organic matter mediated aquatic transport of chlorinated dioxins. Chemosphere 15, 9-12. 

The aquatic transport of uranium as carbonate complexes is reflected in the formation of the uranyl carbonate minerals Rutherfordine, U02(C03), Leibigite, Ca2[U02(C03)3]-10-llH20, and Andersonite, Na2Ca[U02(C03)3]-6H20. Both natural and synthetic UO2CO3 have similar structures which contain sheets of planar ions. The uranyl groups have the normal trans... 

Such molecular studies offer some advantages over the pollen record when reconstructing local climate, because pollen distributions are strongly influenced by ae-olian transport and the amount of pollen produced by different species, whereas leaf and wood components are more likely to be deposited in situ (although some aquatic transport is possible). 

PROCESSES AEEECTINC AQUATIC TRANSPORT AND FATE 4.1. Mercury Oxidation and Reduction... 

These appHcations require withdrawal of water from a source and subsequent treatment and conveyance to the point of use. Water is also used without being withdrawn from a source, eg, for navigation, recreation, wild and aquatic life propagation, hydroelectric-power generation, and waste assimilation and transport. The principal types of withdrawal uses and their average rates are given in Table 2. Some of these withdrawal rates represent multiple uses of the same water along main rivers in metropoHtan and industrialized areas. 

Environmental problems associated with PCBs are the result of a number of factors. Several open uses of PCBs have resulted in thein direct introduction into the environment, eg, organic diluents careless PCB disposal practices have resulted in significant releases into aquatic and marine ecosystems higher chlorinated PCBs are very stable in thein persistence in different environmental matrices and by a variety of processes (Fig. 1) PCBs are transported throughout the global ecosystem and preferentiaHy bioconcentrate in higher trophic levels of the food chain. 

Acid deposition refers to the transport of acid constituents from the atmosphere to the earth s surface. This process includes dry deposition of SO2, NO2, HNO3, and particulate sulfate matter and wet deposition ("acid rain") to surfaces. This process is widespread and alters distribution of plant and aquatic species, soil composition, pH of water, and nutrient content, depending on the circumstances. 

Source Terms and In-Plant Transport the fraction of the inventory that makes it to the environment must be estimated. Computer models are to track the hazardous materials that are released from their process confinement through transport and deposition inside the plant to their release into the environment as a source term for atmospheric and aquatic di.spersion. 

The CESARS database contains comprehensive environmental and health information on chemicals. It provides detailed descriptions of chemical toxicity to humans, mammals, aquatic and plant life, as well as data on physical chemical properties, and environmental fate and persistence. Each record consists of chemical identification information and provides descriptive data on up to 23 topic areas, ranging from chemical properties to toxicity to environmental transport and fate. Records are in English. Available online through CCINFOline from the Canadian Centre For Occupational Health and Safety (CCOHS) and Chemical Information System (CIS) on CD-ROM through CCIN-FOdisc. 

Generally, the main pathways of exposure considered in tliis step are atmospheric surface and groundwater transport, ingestion of toxic materials that luu c passed tlu-ough the aquatic and tcncstrial food chain, and dermal absorption. Once an exposure assessment determines the quantity of a chemical with which human populations nniy come in contact, the information can be combined with toxicity data (from the hazard identification process) to estimate potential health risks." The primary purpose of an exposure assessment is to... 

The Reactions and Physical Transport tlie chemical and biological transfornuition, and water movement, that result in different levels of water quality at different locations in time in an aquatic ecosystem. 

Research into the aquatic chemistry of plutonium has produced information showing how this radioelement is mobilized and transported in the environment. Field studies revealed that the sorption of plutonium onto sediments is an equilibrium process which influences the concentration in natural waters. This equilibrium process is modified by the oxidation state of the soluble plutonium and by the presence of dissolved organic carbon (DOC). Higher concentrations of fallout plutonium in natural waters are associated with higher DOC. Laboratory experiments confirm the correlation. In waters low in DOC oxidized plutonium, Pu(V), is the dominant oxidation state while reduced plutonium, Pu(III+IV), is more prevalent where high concentrations of DOC exist. Laboratory and field experiments have provided some information on the possible chemical processes which lead to changes in the oxidation state of plutonium and to its complexation by natural ligands. 

These various broad research observations generated questions about the influence of chemical environments in aquatic systems upon plutonium and what chemical species might be present. The oxidation states of plutonium, its associations with DOC, and its complexation by inorganic ions all seemed interrelated and important to the understanding of environmental transport. 

The Table of Contents for this collection will facilitate this discussion. Notice that the papers are grouped into the categories of Atmospheric, Aquatic and Terrestrial Components, Global Carbon Cycle and Climate Change, and Global Environmental Science Education. The reader may want to consider the various chemical species studied in each paper. Next, the reader may wish to group the papers by whether they address the source or the receptor, the transport or transformation processes for the chemical species. Finally, the reader needs to establish the time scales and the spatial resolution used. 

On a global scale, the atmosphere serves as the major pathway for the transport and deposition of contaminants from emission sources to terrestrial and aquatic ecosystem receptors (22, 27). Once a contaminant is airborne, the processes of atmospheric di sion, transport, transformation, and deposition act to determine its fate. These processes are complex and the degree to which they influence the fate of a particular contaminant is dependent on its physico-chemical characteristics, the properties and concentrations of coexisting substances, and the prevailing meteorological conditions, including wind, precipitation, humidity, temperature, clouds, fog, and solar irradiation. 

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