UC Davis

This paper describes measurements of residual stress in thin slices removed from the wall of a pressurizer safety/relief nozzle, which is a cylindrical welded component found in a nuclear power pressurized water reactor. Because the slices comprise a cross-section through a dissimilar metal weld that joins the low-alloy steel pressurizer to a stainless steel safe-end, the residual stress measurements are difficult. Typical welds have large grains and preferred orientations, along with chemical and phase gradients, that challenge diffraction techniques using neutron or x-ray beams. Welds also contain spatial gradients of residual stress that challenge mechanical release techniques like contour, slitting, and hole drilling. Therefore, the paper describes the application of, and compares the results from, three applicable residual stress measurement techniques: slitting, electronic speckle pattern interferometry hole drilling, and neutron diffraction. The results of slitting and neutron diffraction are in rough agreement, while the results from hole drilling are significantly different. An uncertainty analysis shows that slitting results had the smallest uncertainty, followed by hole drilling, and that neutron diffraction results had large uncertainty, particularly in the weld.