High temperature reactor design evaluation program for metallic pressure boundary with multiple transient peak-valley determination and graphite components

The design evaluation procedures of Class A metallic pressure boundary and graphite components under high temperature conditions, such as in Generation IV reactors, are highly complex. In particular, creep-fatigue damage evaluation requires the identification of peak and valley points for multiple transient cycles. In this paper, design evaluation procedures for Class A metallic pressure boundary and graphite components are implemented in a design evaluation program, named HTRspro (High Temperature Reactor structural evaluation computer program) for reliable and efficient evaluation. The design evaluation program includes not only creep-fatigue damage evaluation but also procedures for load-controlled stress limits, strain and deformation limits, and for graphite core component evaluation. Methods for determining peak and valley points to evaluate creep and fatigue damage under multiple transient cycles are proposed and applied to the program. Material properties presented in the ASME B&PV Code are embedded in the program, and detailed parameters can be input by users. The program is verified by comparison with Excel-based hand calculation results for an example of Volume Control Tank (VCT). In addition, creep-fatigue damage evaluation, including a cycle combination procedure for multiple transient cycles, is performed, and the evaluation results based on the proposed peak-valley determination methods are analyzed.