- The fatigue assessment of safety relevant components is of importance with regard to safety and reliability of nuclear power plants. Due to their excellent mechanical and technological properties as well as their corrosion resistance austenitic stainless steels are often used for reactor internals. Internals are subject to mechanical and thermo-mechanical loading in all fatigue regimes. This work presents the current status of the research project VHCF-II with the goal of improved fatigue life prediction for safety assessment of the materials AISI 304L, AISI 347 and ER 347. For improved fatigue life prediction, the static and cyclic material behavior is characterized at ambient and operation relevant temperatures. A detailed characterization of the material behavior is required to determine the components’ fatigue life up to 109 load cycles with Ultrasonic Fatigue Testing Systems (UFTS) working at 20 kHz. The characterized material data serve the purpose to expand the data for improving methods of fatigue calculations. For this purpose, numerical simulations of thermo-mechanically loaded components with focus on their welded joints are conducted. Experiments are conducted in order to further validate the methods of fatigue life assessment under operating conditions of nuclear power plants. Foreseen and ongoing work of the VHCF-II project is presented in this paper.
