Offices: The Netherlands Leeghwaterstraat 21 2628 CA Delft Tel.: +31 15 278 2907 Germany Weenermoorer Str. 193 26826 Weener Tel.: +49 4953 922 969 Consultancy for Heat Transfer and Fluid Dynamics CFD makes fluid dynamics visible. We solve every Flow problem. In times of increasing environmental awareness many governments have deci-  ded to reduce the contribution of nuclear power to the total primary energy pro-  duction. Since then there is a strong demand for containers to transport and store  the highly radioactive waste safely. The world market leader GNB develops and  manufactures such container taking enormously strict safety rules into account.   One of these rules are mechanical integrity (even in catastrophes), protection  against radiation and thermal load. Because of the interaction between the  various demands, the development and design of these containers requires a  multidisciplinary team of experts in materials, mechanics and fluid dynamics.  FlowMotion has been asked to add their expertise in fluid dynamics and heat  transfer to the team and to work on the heat transfer of the container to the  surroundings.  Heat dissipation is a very important topic for  the container. The nuclear waste in the inside  still producing a large amount of thermal energy. An insufficient heat dissipation  would lead to an strong increase of the container temperature, which could damage  the internal structure and therefore could cause leakages or high surface  temperatures could endanger the environment. Thus the container is protected by  a cap during transportation. Since this cap has a significant influence of the heat  dissipation of the container to the surroundings, the different version of the cap  have been taken into account in the thermal design of the container.  FlowMotion has simulated the air flow in and outside the cap and the resulting total  heat dissipation of the container with the help of CFD (Computational Fluid  Dynamics) calculations. In these simulations free convectional flow along all  components no approximation by heat transfer coefficients), thermal conduction within the solids and thermal radiation  have been calculated. Aim of the simulations was to determine the accuracy of the simulation with respect to real scale  measurements and finally to use the numerical results in the design process of the container and the cap.  In the future the CFD calculation will also help to optimize the entire heat transfer process, to continuously guarantee  safety for everybody even for the transportation and storage of nuclear waste with a much larger production of  thermal energy. Save containers for nuclear waste Heat transfer calculation for transportation container of nuclear waste Gesellschaft für  Nuklearbehälter mbH www.gns.de temperature