British Energy funded a large programme to pre-emptively investigate the use of structural weld overlays (SWOLs) to mitigate against crack initiation and growth within the dissimilar metal welds (DMW) found in the pressuriser safety/relief valve nozzle components in their Sizewell B nuclear power plant (NPP). Deep-hole drilling (DHD) measurements were carried out to provide confidence in and hence validate the residual stresses predicted along the DMW centreline of the “virgin” and “overlaid” nozzle using finite element analysis (FEA). The predicted residual stresses were then used for subsequent fatigue crack growth rate analysis. The residual stresses measured at all three locations within the “virgin” nozzle were in very good agreement, while for the “overlaid” nozzle good agreement was seen at depths greater than 25% from the inner surface of the nozzle. It was found that the SWOL reduces the magnitude of the tensile stresses in the underlying DMW and causes a much deeper compressive stress zone. Relatively good agreement was observed between the FEA results and the measurement results.
|Translated title of the contribution||Through Thickness Residual Stress Measurement in a Full Structural Weld Overlay on PWR Pressuriser Nozzle|
|Title of host publication||International conference on Structural Mechanics in Reactor Technology|
|Pages||1 - 8|
|Volume||Div-II: Paper ID 153|
|Publication status||Published - 2011|