Source Term Evaluation

Osborne, M.F., Collins, T.L., Lorenz, R.A. Strain, R.V. (1986) Fission product release and fuel behaviour in tests of LWR fuel under accident conditions. In Source Term Evaluation for Accident Conditions, IAEA, Vienna, pp. 89-104. 

The sets of ODEs represented by Equations 8.34 and 8.35 have I — 1 members for each chemical component and another 7-1 members for temperature. Three points at the old z location plus source terms evaluated at the old, central location are used to calculate the central point at the new, z + Az, location. Figure 8.2 shows a template that illustrates the calculation. The template is initially centered at the point i = 0 and is moved to higher values of iuntil the point 7 — 1 is reached. The value at the wall is obtained from the wall boundary condition, (e.g.. Equation 8.32). The template is then returned to t = 0 and moved one step in the axial direction, y new = j + 1, until the... 

STI/PUB/700 Source Term Evaluation for Accident Conditions STI/PUB/701 Emergency Planning and Preparedness for Nuclear Facilities STI/PUB/716 Optimization of Radiation Protection... 

S-17. D A. Powers, A re-examination of the steam explosion source term during severe accidents p.391. Source Term Evaluation for Accident Conditions, International Atomic Energy Agency, Vienna Austria, 1986. 

Source term evaluation and categorization, for example, LERF... 

There is a need to improve consistency in source term evaluation methods and other methods for calculating radiological consequences of accidents. 

Jones,A. V., Shepherd, I.M. ESTER - a European Source Term Evaluation System. The Phebus Fission Product Project (ed. W. Krischer M.C. Rubenstein) (Elsevier, London) (1992)... 

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. 

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... 

Except for the chemical source term, these equations have the same form as those used for the mixture fraction. Note that the chemical source term (S oo) is evaluated using the mixture fraction and reaction-progress variable in the particular environment. The average chemical source term (S2oo(Y2) will thus not be equal to S2cc, (( ), (Y2)) unless micromixing occurs much faster than the second reaction. 

The last term in (1.34) follows by approximating S evaluated at the bin center by its value at a sample point contained in the bin. In the limit where the fine grid becomes infinitely fine, the last term is just the spatial-average chemical source term ... 

In Section 5.6, Lagrangian micromixing models based on mixing environments were introduced. In terms of the joint composition PDF, nearly all such models can be expressed mathematically as a multi-peak delta function. The principal advantage of this type of model is the fact that the chemical source term is closed, and thus it is not necessary to integrate with respect to the joint composition PDF in order to evaluate the... 

In this equation, C is the concentration of element i in pore water at depth z below the seafloor and A is a reaction (sink and source) term. For reactions involving the oxidation of organic matter, A can be evaluated independently. For constant porosity , the sulfate transport equation becomes... 

Chen, Y. 2003. Using reactive transport modeling to evaluate the source term at Yucca Mountain. Computers Geosciences, 29, 385-397. 

To evaluate fission product release in a reactor, it is necessary to supply the appropriate particle geometry, diffusion coefficients, and distribution coefficients. This is a formidable task. To approach this problem, postirradiation fission product release has been studied as a function of temperature. The results of these studies are complex and require considerable interpretation. The SLIDER code without a source term has proved to be of considerable value in this interpretation. Parametric studies have been made of the integrated release of fission products, initially wholly in the fueled region, as a function of the diffusion coefficients and the distribution coefficients. These studies have led to observations of critical features in describing integrated fission product releases. From experimental values associated with these critical features, it is possible to evaluate at least partially diffusion coefficients and distribution coefficients. These experimental values may then be put back into SLIDER with appropriate birth and decay rates to evaluate inreactor particle fission product releases. Figure 11 is a representation of SLIDER simulation of a simplified postirradiation fission product release experiment. Calculations have been made with the following pertinent input data ... 

The DNS model can be deployed subsequently on the liquid water blocked CL structure pertaining to a saturation level for the evaluation of the hindered oxygen transport. In brief, the DNS model is a top-down numerical approach based on a fine-scale CFD framework which solves point-wise accurate conservation equations for species and charge transport in the CL with appropriate source terms due to the oxygen reduction reaction (ORR) directly on the CL microstructures.25-27 67 The conservation equations for proton, oxygen and water vapor transport, respectively, are given by 25-27 68... 

---