Numerical Study on the Creep Strain Characteristics for TMSR Reactor Coolant Piping Under Thermal Loading

Safety assessment and economy design of piping system at high temperature is highly important in power and nuclear engineering. ASME-NH code considers cyclic failure modes at elevated temperature and provides the rules and damage limits for creep-fatigue interaction. Based on the calculation methods for creep strain increment of ASME-NH code, this paper investigated the creep-fatigue damage of reactor coolant piping in Thorium Molten Salt Reactor-Solid Fuel (TMSR-SF0) loop. By designing different stress cycles, the different creep strain increment and creep-fatigue assessments are systematically conducted. It was found that the creep strain increment of SF0 loop accumulated in one stress cycle time was higher than that accumulated during the entire service life divided by the number of stress cycles. Similarly, the creep-fatigue damage was also lower. And thus, an economical design method for SF0/SF1 loop was given.