Thermal and structural behaviour of various first-wall concepts

The thermal-structural behaviour and performance of fusion power plant first-wall concepts is analysed with the aid of a finite element analysis code, and conclusions are drawn. This study is an integral part of a wider research effort undertaken by AEA Technology, which involves the development of methods for the detailed assessment of fusion-related systems and components. Outline designs based on earlier work are further developed and assessed, with emphasis placed on safety issues and performance. The technical objectives of this research effort comprise detailed design aspects of the first wall, assessment of materials performance, prediction of failure, estimation of service life and layout of modelling methodology, using available neutronics and finite element analysis software packages. Under normal operating conditions, the performance of the first wall depends on the thermal and internal coolant (if any) pressure loading conditions; during a disruption, it also depends on the plasma decay-current-induced magnetic pressure (force). The thermal and structural analysis comprises performance comparisons of rectangular, circular and elliptical cooling channel cross-sections, assuming as first-wall structural materials the austenitic (316) and martensitic (Manet) stainless steels and a vanadium alloy. A parametric study is included, with variable surface heat flux in the range 0.1-0.6MWm-2 and a volumetric heat flux in the range 15-25MWm-3. For steady state operation, the maximum temperature is in the range 550-650 C, the maximum thermal stress is in the range 150-650MPa and the maximum strain is in the range 0.13-0.27. In general, the designs examined are shown to be capable of withstanding the loading conditions imposed, although the effect of factors such as pulsed or part load operation should be carefully examined. ((orig.))