Minimization of the effect of errors in approximate radiation view factors

Abstract

The maximum temperature of irradiated fuel rods in storage containers was investigated, taking account only for radiation heat transfer. Estimating view factors is often easy but the emphasis is often on calculating the quadruple integrals exactly. Selecting different view factors in the view factor matrix as independent, yields somewhat different view factor matrices. In this study, errors of 10%–20% in view factors produce small errors in the temperature, which are well within the uncertainty resulting from the surface emissivities uncertainty. However, the enclosure and reciprocity principles must be strictly observed, or large errors in the temperatures and wall heat flux are observed (up to a factor of 3). In addition to being an aid for calculating the dependent view factors, satisfying these principles, particularly reciprocity, is more important than the calculation accuracy of the view factors. Comparison with experiment showed that the results of the radiation calculation were definitely conservative, as desired, despite the approximations of the view factors.