Weld residual stress evaluation of reactor pressure vessel considering material property changes of heat-affected zone due to weld-overlay cladding

Nishikawa, Hiroyuki; Katsuyama, Jinya  ; Udagawa, Makoto; Nakamura, Mitsuyuki; Onizawa, Kunio 

In order to evaluate residual stress distributions in the vessel wall of a reactor pressure vessel (RPV) due to weld-overlay cladding and post-weld heat-treatment (PWHT), thermal-elastic-plastic-creep analysis considering the changes of material properties in heat-affected zone (HAZ) has been performed. Analytical results of stress distributions considered the material property changes in HAZ agreed well with the ones measured experimentally from weld-overlay cladded plates. Applying the analysis method to a RPV model, through-wall residual stress distributions caused by weld-overlay cladding, PWHT, hydrostatic test, operational load and transient loads during pressurized thermal shock (PTS) events have been computed. Effects of the weld-overlay cladding on the stress distributions in the vessel wall of a RPV have been evaluated. Using the stress distributions, stress intensity factors for a postulated crack during PTS events have been studied.