High-temperature material properties of type 316L stainless steel for the design of pressure boundary components subjected to 700°C coolant

The high-temperature material properties of Type 316L stainless steel (hereafter referred to as "316L SS") were determined through a series of material tests to enable the design of pressure vessels and piping operating up to 700 degrees C. Currently, the only applicable design rule for 316L SS components in the high-temperature creep range is French high-temperature design standard, RCC-MRx. However, the material properties provided by RCC-MRx are limited to approximately 600 degrees C. In this study, new material properties and relevant design coefficients for Type 316L components subjected to 700 degrees C coolant were determined based on material tests including tension, fatigue and creep tests conducted on 316L SS specimens. Utilizing these supplemented properties and design coefficients, the design of pressure boundary components and piping made of 316L SS in a large-scale test facility known as TESET, subjected to 700 degrees C coolant, was carried out. Several large-scale sodium tests at high temperatures up to 700 degrees C were successfully conducted at the TESET facility, with the main components and piping designed and constructed using 316L SS.