2009 年 27 巻 2 号 p. 245s-250s
Numerical simulations by thermal-elastic-plastic-creep analysis using finite element method (FEM) have been performed to evaluate residual stress distributions in a reactor pressure vessel (RPV) caused by weld-overlay cladding, post-weld heat treatment (PWHT), hydrostatic test, operation and pressurized thermal shock (PTS). The weld-overlay cladding gives tensile stress in the cladding layer and base metal near the cladding. Using the calculated welding residual stress, stress intensity factors (SIFs) during PTS have been computed based on the influence function method. The maximum value of SIF during PTS with weld-overlay cladding is higher than that without weld-overlay cladding. According to the structural integrity assessment procedure of an RPV against PTS, a comparison has been also made by defining a temperature margin. The result indicates that the residual stress makes the temperature margin smaller in a few degree C which may be within the range of the margin originally put in the structural integrity assessment procedure.
