Comparison of numerical and semi-analytical analyses of temperature fields of loaded dry casks

A key parameter to predict the integrity of the fuel rod cladding during dry storage is the temperature. Almost all degradation mechanisms are temperature dependent. A realistic prediction of the temperature field at a given time for the loaded cask is needed to investigate predictions for long-term degradation mechanisms properly. Overly conservative temperature estimates with the purpose to assure peak cladding temperatures within technical specifications might lead to non-justified, even counterproductive conclusions. In this work, we present two modelling approaches used to calculate temperature fields of loaded casks. One approach is a detailed numerical simulation via a specific code, and the second is a semi-analytical approach focusing on a faster and feasible calculation. Steady-state and transient calcidations are compared and discussed for both modelling approaches.