Thermo-mechanical Analysis of a Helium Cooled Divertor of a Fusion Reactor I. Simonovski, B. Koncar and L. Cizelj

摘要

The development of the divertor for the forthcoming DEMO fusion reactor stipulates heat flux loads larger than 10 MW/m~2. Successful design should withstand such high loads for a number of load cycles. One of the possible divertor configurations is also a divertor concept where the cooling is provided by multiple helium cooling jets (HEMJ) Widak and Norajitra [2009]. In this work we propose a combined computational fluid dynamics and structural model for evaluating the structural response pf the HEMJ design under the EFREMOV test experimental conditions Gervash et al. [2006]. Heat transfer coefficients between the helium and inner surface of the thimble are first calculated using a steady state response solution. Calculated coefficients are then used as a boundary condition in a thermo-mechanical analysis of the divertor. The analysis is performed for a number of load cycles under different surface heat flux levels. Good agreement of the highest temperatures on the tile's top surface with the experimental data is obtained. The calculations suggest that there are three areas in the design where excessive fatigue would occur: a) the thimble's inner surface with the highest thermal gradients, b) tiles outer surface and c) the layer between the tile and the thimble where the temperature is higher that permissible. Post-examination data of the performed tests confirm these conclusions as cracks were observed at the above mentioned areas a) and b), while melting of the layer c) was also observed.