Evaluation of Source Terms

The source term 5fg in the momentum equation represents the resistance of gas flow by the solid adsorbent (packing particles), which can be calculated by [5]  

The source term 6tg in the adsorbate conservation equation for gas phase can be expressed by  

The first term on the right-hand side of foregoing equation represents the transfer of heat of adsorption from the outer surface of solid adsorbent particle to the gas phase the second term represents the heat transfer from the gas phase to the column wall. In the equation, hg is heat transfer film coefficient between solid adsorbent surface and the gas phase Op is the outer surface of the solid adsorbent Ts is the outer temperature of the solid adsorbent Tq is the temperature of the gas 

The source term 5ts in the equation of energy conservation for solid adsorbent can be written as follows  

The source term 5xw in the energy conservation equation for the column wall is given by  

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The second element is the safety analysis and technology. It determines the conditions to meet the safety requirements, such as evaluation of source terms and consequences, engineering design to prevent and mitigate an accident. 

An accident at a nuclear power plant can be caused by many combinations of anomalous initiating event, malfunction and human error. The types of possible accidental situations are studied in the specific safety analysis of each plant and the safety systems described above are designed to prevent, or mitigate the effects of all the accidents chosen as DBAs. Table 3-1 provides an approximate indication of the effectiveness of various safety systems in limiting external releases in a typical loss of coolant accident (the break of a large primary circuit pipe). The figures are for the release of iodine-131 (often assumed as the reference isotope in indicative evaluations of source terms and for a 1000 MWe reactor). As can be seen, the reduction of the releases caused by the safety systems is very significant and corresponds to a factor of the order of one million. 

In this modeling form, abbreviated as interacted liquid phase model, the liquid phase is considered as the system to be concerned aiming to obtain the transport information of the liquid phase. The dispersed phase is considered as the sm-roundings. The action of the dispersed phase (bubbles) on the liquid phase is treated as the external forces acting on the system (liquid phase). Thus, the evaluation of source term Su in Navier—Stokes equation of liquid phase should cover all the acting forces by the dispersed gas phase to the liquid phase. Such model can reduce the number of model equations and computer load. Computation shows that whether the interaction source term Su is properly considered, the final simulated result is substantially equal to that using two-fluid model (Fig. 3.7). 

The boundary conditions and the evaluation of source terms are the same as... 

The simulation is by using standard Reynolds mass flux model the model equation sets, the boundary conditions, and the evaluation of source terms are the same as given in Sect. 5.1.3. The simulated results are given in the following sections. 

Evaluation of source terms The evaluation is the same as in Sect. 6.1... 

As described in Chapter 7, the source term can be treated using QBMM, where the weights and abscissas are computed from the multivariate moments. It will thus be necessary to design a realizable ODE solver for use with the source term in Eq. (B.l). In the remainder of this appendix, we assume that such an ODE solver exists, and thus we focus our attention on the spatial-transport solver. Nevertheless, the reader should consult Yuan Fox (2011) for details on how to use the CQMOM with multiple permutations to evaluate the source term in a statistically consistent manner. Briefly, when using the CQMOM... 

The accident analysis follows basically the same approaches described in Parts 2 and 3 except that it is quantitative and it requires more detailed information on facility designs and operations. The accident analysis includes development of scenarios, evaluation of probability of occurrence, calculation of source terms, and calculation of consequence. Based on the analysis, a set of safety requirements is developed for accident controls. Because of the time limit, the details will not be discussed here. 

This early work, and those that followed, illustrated issues that arise when using the MEF to predict drop size distributions formulating the constraints is not trivial because it is difficult to determine a priori which ones should be included and which ones omitted the presence of source terms, which are difficult to evaluate and the fact that/o does not always approach zero at small diameters. The latter issue was overcome by invoking an additional constraint ... 

IV-4. In the case of fast reactors, the secondary coolant circuit enters the neutron flux and it is necessary to evaluate the source terms that are due to corrosion of the secondary circuit. Some of the important phenomena that affect the source term for corrosion products are the following ... 

Design of experiments. When conclusions are to be drawn or decisions made on the basis of experimental evidence, statistical techniques are most useful when experimental data are subject to errors. The design of experiments may then often be carried out in such a fashion as to avoid some of the sources of experimental error and make the necessary allowances for that portion which is unavoidable. Second, the results can be presented in terms of probability statements which express the reliabihty of the results. Third, a statistical approach frequently forces a more thorough evaluation of the experimental aims and leads to a more definitive experiment than would otherwise have been performed. 

Emrit, R. et al., A Prioritization of Generic Safety Issues, NUREG-0933 suppliment. Reassessment of the Technical Bases for Estimating Source Terms, Draft, May 1985. Baranowsky, P.W., Evaluation of Station Blackout Accidents at Nuclear Power Plants, May 1985. 

The preceding oversimplified mathematical treatment really amounts to an evaluation of the absorption effect (6.1). The exponential term in Equation 6-4 is obviously a product of two exponential terms, each deriving from Beerks Law. One term governs the attenuation of the beam incident upon the volume element in question, and the other governs the attenuation of the characteristic line emerging frcJm this element. The films are so thin that the use of one value each for 6 and for 02 over the entire film thickness is justified. Finally, one must assume that the intensity measured by the detector remains proportional to the intensity of the source. An exact treatment of the problem would be so complicated that one is justified in seeing what can be done with the simple relationships obtained above. 

Here, the temperatures on the left-hand side are the new, unknown values while that on the right is the previous, known value. Note that the heat sink/source term is evaluated at the previous location, — A. The computational template is backwards from that shown in Figure 8.2, and Equation (8.78) cannot be solved directly since there are three unknowns. However, if a version of Equation (8.78) is written for every interior point and if appropriate special forms are written for the centerline and wall, then as many equations are... 

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