Effects of weld-overlay cladding on the structural integrity of reactor pressure vessel during pressurized thermal shock

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

Weld-overlay cladding of austenitic stainless steel is applied to the inner surface on ferritic low-alloy steel of RPV for protecting from corrosion. After the manufacturing processes of an RPV including weld-overlay cladding, post-weld heat treatment (PWHT) and pressure test, welding residual stress still remains in such dissimilar metal welds, which could affect the structural integrity of RPV during PTS. In the present study, thermal-elastic-plastic analysis using finite element method has been performed to evaluate residual stress distribution in reactor pressure vessel produced by weld-overlay cladding. Stress intensity factor during PTS has been calculated using PFM analysis code (PASCAL2). The stress intensity factor considering weld-overlay cladding is larger than that of no weld residual stress.