Migration estimates

The text of this clause is yet provisional and will be improved later. To develop and validate a migration estimation model for the above purpose, the Commission approved a project entitled Evaluation of Migration Models to be Used under Directive 90/128/EEC . A final objective of this project is a proposal of a validated migration model to the European Committee of Standards (CEN) for standardization. 

In Chapter 11 it was shown that Limm and Hollifield (1996) proposed a somewhat similar approach to calculate DP for migration estimation purposes ... 

From the point of view of compliance applications the use of Eq. (15-3) and the parameters from Table 15-2 for migration estimation may in principle lead to two types of results. 

Once these two experimental steps are done their results can be used to obtain the necessary specific parameters in Eq. (15-3), which then can be used in conjunction with Eq. (7-51) to perform migration estimations for a new or unknown plastic material. 

Prinzhofer, a., Mello, M. R. Takaki, T. 2000. Geochemical characterization of natural gas a physical multivariable approach and its applications in maturity and migration estimates. American Association of Petroleum Geologists Bulletin, 84, 1152-1172. 

S. M. Ah, "An Updated Version of Computer Code CORA II for Estimation of Corrosion Product Mass and Activity Migration ia PWR Primary Circuits and Related Experimental Loops," Eourth International Conference on Water Chemistry of Nuclear Systems, Bournemouth, U.K., Oct. 1986, pp. 107-109. 

Many times solids are present in one or more phases of a solid-hquid system. They add a certain level of complexity in the process, especially if they tend to be a part of both phases, as they normally will do. Approximate methods need to be worked out to estimate the density of the emulsion and determine the overall velocity of the flow pattern so that proper evaluation of the suspension requirements can be made. In general, the solids will behave as though they were a fluid of a particular average density and viscosity and won t care much that there is a two-phase dispersion going on in the system. However, if solids are being dissolved or precipitated by participating in one phase and not the other, then they will be affected by which phase is dispersed or continuous, and the process will behave somewhat differently than if the solids migrate independently between the two phases within the process. 

Simplified environmental fate estimation procedures are based on the predominant mechanisms of transport within each medium, and they generally disregard intermedia transfer or transformation processes. In general, they produce conservative estimates (i.e., reasonable upper bounds) for final ambient concentrations and the extent of hazardous substance migration. However, caution should be taken to avoid using inappropriate analytical methods that underestimate or overlook significant pathways that affect human health. 

This equation has been used for estimating migration velocities of radionuclides (e.g. 66). Here Pr is the density of the rock (kg/m3), p the density of water, e the fissure porosity, af the specific surface of fissures in the bedrock (m2/m3) and ap the specific surface of particles used in the Kd determinations (m2/m3). The distribution coefficient Kd represents ar. equilibrium value for the particular rock under the pertinent conditions. 

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