Abstract
The fatigue assessment of pressurized components is of high importance for the operation of nuclear power plants. However, the environmental influences on the fatigue behavior are highly discussed. On the one hand, laboratory specimens tested in high temperature water (HTW) conditions show a significant drop in fatigue lifetime, compared to tests at air environment, and question the conservatism of modern standards. On the other hand, the fatigue assessment methods based on uniaxial tensile testing seems to overestimate the fatigue damage of components during operation. To overcome these discrepancies, the environmental influences on material fatigue have to be better understood. Laboratory testing setups have to be adapted to the relevant loading conditions during power plant operation. Therefore, MPA Stuttgart is investigating the environmentally assisted fatigue (EAF) of steels under various loading conditions for smooth and notched specimens, as well as full scale component testing at HTW conditions. In this paper the results of ongoing research are presented. The low cycle fatigue experiments on steel materials for relevant nuclear applications are performed at air and under pressurized water reactor (PWR) environment. The shape of specimens, the loading spectra, loading rate and the multiaxiality of load are derived from piping components in power plant operation.
Analytical Approach to Sampling Estimation of Underwater Tunnels Using Mechanical Profiling Sonars
