A design based approach to material selection for advanced high temperature reactor components

Material selection decisions for advanced reactor concepts are frequently based on simple consideration of required wall thickness for a particular component and the resultant cost based on averaged cost per unit, usually by weight. However, this approach does not take into consideration the overall impact of other material properties on design feasibility. An example would be the interrelated roles of thermal conductivity, thermal expansion and creep-strength on the design of components to withstand cyclic and sustained loading. The problem is that this would nominally require a detailed design and loading definition. However, as presented herein, a meaningful comparison can be achieved by selective evaluation of the ratios of the material properties required to achieve a particular performance goal for a particular design objective; for example, the relative ability to accommodate axial thermal gradients in a pressurized cylindrical vessel. This paper covers the development of such critical parametric ratios for a number of component elements and loadings and illustrates their application.