• blanket
• fusion
• ITER
• thermo mechanical analyses

The aim of this thesis is to perform thermo-mechanical analyses and design optimization of the Helium Cooled Pebble Bed Test Blanket Module (HCPB-TBM) box. In the frame of the EU-TBM Consortium of Associates, and with the support of Fusion for Energy (F4E), the Karlsruhe Institute of Technology (KIT) designed and developed the HCPB-TBM. The TBM works as first wall, breeding blanket, shielding and structure. In particular the TBM box has to withstand extremely severe thermo-mechanical conditions. The thermal and mechanical analyses have been carried out with the Finite Element commercial code ANSYS and have been compared by a theoretical approach. Starting from the reference configuration of the HCPB-TBM box and its loading conditions, steady state and transient thermal analyses of the box and its internal components have been performed, under normal and accidental conditions. Subsequently design optimizations of the reference configuration have been proposed and analyzed in order to improve the thermal behavior of the components. Moreover the TBM first wall has been analyzed. Steady state and transient thermal analyses have been performed in order to identify critical areas and to investigate the impact of key design parameters on the FW thermal performances. Two transient thermal analyses have been carried out. The first transient thermal analysis simulates an ITER pulse, while the second has been based on accidental scenario, that is an ex-vessel loss of coolant accident (LOCA) caused by a double-ended pipe break of a helium coolant pipe. Ex-vessel LOCA is considered as one of the most critical accident for the HCPB TBM. The loss of helium could cause an immediate loss of the TBM cooling capabilities, and would initiate a prompt plasma shutdown. Even after the plasma shutdown the temperature on the TBM FW could increase above the design limit and the accident sequence could cause the break of the TBM box. Models sensitivity studies were performed. The sensitivity studies have been performed for all subcomponents in order to analyze the model response to the variation of the input parameters. The sensitivity studies allow to take into account the uncertainties of the input data and their impact on the temperature distribution. After the thermal studies, mechanical analysis of the TBM first wall, based on a simplified model was performed. FE simulations as well as theoretical approaches have been compared. The obtained stresses have been compared with the allowable stress limits prescribed by SDC-IC ITER structural codes.