Dispersion, mitigation measures

In the analysis it was assumed that the water-spray curtain was activated within one minute of the start of the incident and that 86% of the HF vapor from the evaporating pool that reached it was removed. The balance of the HF not removed by the water sprays became the material that formed the reduced hazard zone and the input for the dispersion modeling. For the F/l meteorological conditions the mitigated hazard zone for the centerline concentration of 20 ppm was 750 m. The effectiveness of water spray as postrelease mitigation measure is shown in Table 7.6. 

Dispersion of chemicals into the environment may occur via ground and surface water or sanitary and storm sewer systems. Gases, vapors and combustion products can be dispersed in the air. In addition, particulate matter and condensate can precipitate out of smoke plumes. The risks to the public will be the result of several variables, including quantities, physical properties and hazards, as well as the adequacy and effectiveness of mitigation measures. 

The release mitigation procedure is part of the consequence modeling procedure shown in Figure 4-1. After selection of a release incident, a source model is used to determine either the release rate or the total quantity released. This is coupled to a dispersion model and subsequent models for fires or explosions. Finally, an effect model is used to estimate the impact of the release, which is a measure of the consequence. 

Since van der Waals forces are responsible for the coagulation of lyophobic colloids, the mitigating influence of the continuous phase on the attraction between dispersed particles imparts a measure of stability to the system. This result was anticipated in our remarks about... 

Such measurements could indicate the presence of significant levels of clay bearing minerals in the processed ores at any time hence the occurrence of the clay-related problems can be mitigated through the implementation of controlled dispersion strategies only when necessary. 

The temperature of tissue was measured by Barlow et al. in 1995 [125]. Absorbance changes in the water spectrum between 700 and 1600 nm (in transmission) and the spectrum between 800 and 2200 nm (reflectance) were found to correlate with the temperature of the tissue in which the water is contained. The standard error of estimate (SEE = 0.02 to 0.12°C) and standard error of prediction (SEP = 0.04 to 0.12°C) were found. Since tissue in general is a highly dispersing medium, various attempts have been made to mitigate this scattering. 

---