Dilute and disperse

Several modes of waste management are available. The simplest is to dilute and disperse. This practice is adequate for the release of small amounts of radioactive material to the atmosphere or to a large body of water. Noble gases and slightly contaminated water from reactor operation are eligible for such treatment. A second technique is to hold the material for decay. This is appHcable to radionucHdes of short half-life such as the medical isotope technetium-9 9m = 6 h), the concentration of which becomes negligible in a week s holding period. The third and most common approach to waste... 

Precipitation heavy rain dilutes and disperses chemical weapons snow increases persistence. 

Since the advent of the Industrial Revolution there has been an air pollution problem. For years the control of air pollutants was nonexistent. Many industries and governments suggested that the solution to pollution is dilution, that is, build larger and higher smokestacks to dilute and disperse the fumes before health or the environment are affected. This can no longer be diluted to insignificant concentrations, especially in large metropolitan... 

Hunt, G.J. (1985) Timescales for dilution and dispersion of transuranics in the Irish Sea near Sellafield. The Science of the Total Environment, 46, 261-78. 

Radioactive waste management involves the treatment, storage, and disposal of liquid, airborne, and solid effluents from the nuclear industry s operations, along with those from other activities that employ the radioactive products. Its strategy involves four approaches limit generation, delay and decay, concentrate and contain, and dilute and disperse. Combinations of all four of these usually are employed to manage each waste stream.39... 

Finally, both dilution and dispersion of large volumes of air and water effluents containing very low quantities of radioactivity generally are necessary. The concentration of radioactivity in these effluents is controlled by federal and international regulations, and such effluents are continuously monitored before release to the environment from the waste treatment and other activities. In a particular operation, the regulations may be reflected by a set of actions that are triggered by successively higher levels of radioactivity. 

A second and more likely possibility is that fuel from future reactors will have to be reprocessed, resulting in the dilution and dispersal of the fission products into many media. 

Products will need development and optimization for alcohol- and vegetable oil-based fuels. Evolution is likely to be both composition, to tolerate high levels of fuel dilution, and dispersancy to handle new types of sludge that are likely to be produced. 

The principal radionuclides to be discharged from the plant as originally designed are gaseous tritium and Kr. The 100-m stack provides adequate dilution and dispersion. Equipment for removing Kr will be added when fuel irradiated after 1982 is to be reprocessed. 

SPILL CLEAN-UP use water spray to dilute and disperse vapors flush remaining isobutyl alcohol with large amounts of water but not into confined spaces such as sewers because of danger of explosion absorb small quantities on paper towels and evaporate in fume hood absorb large quantities with non-combustible materials and atomize in a suitable combustion chamber remove all sources of ignition. 

All experiments to date have involved the injection of an iron sulfate solution into the ship s wake to achieve rapid dilution and dispersion throughout the mixed layer (Figure 6). The rationale for using ferrous sulfate involved the following considerations (1) ferrous sulfate is the most likely form of iron to enter the oceans via atmospheric deposition (2) it is readily soluble (initially) (3) it is available in a relatively pure form so as to reduce the introduction of other potentially bioactive trace metals and (4) its counterion (sulfate) is ubiquitous in sea water and not likely to produce confounding effects. Although mixing models indicate that Fe(II) carbonate may reach insoluble levels in the ship s wake, rapid dilution reduces this possibility. 

On the surface, water spraying, site selection, and SCTeening from winds are advantageous, while in underground working sites suppression by water, dilution and dispersion by ventilation and removal by filtration or electrostatic precipitation are advisable. 

Two conceptual models are provided for environments in which Type 3 behavior occurs. For sources with PCE and TCE, the major natural attenuation processes are dilution and dispersion alone (no biodegradation). As shown in 23.1.7, the PCE and TCE plumes extend from the source zone and concentrations are slowly reduced by abiotic processes. Chloride concentrations and oxidation-reduction potential will not change as groundwater passes through the source zone and forms die chlorinated ethene plume. If TCA is the solvent of interest, significant abiotic hydrolysis may occur, resulting in a more rapid decrease in TCA concentrations and an increase in chloride concentrations. 

A common feature of flow analysis is that during sample transport toward the detector, the combined effects of dilution and dispersion decrease the sample concentration, and the extent of these processes is very important for system design. Dilution occurs instantly at every confluence point due to mixing of the sample with the confluent stream. Under ideal mixing conditions, the concentration C of a chemical species in a fluid slice immediately before a confluence point is modified to C according to... 

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