Experimental determination of residual stress by neutron diffraction in a boiling water reactor core shroud

Residual strains in a 51mm (2-inch) thick 304L stainless steel plate have been measured by neutron diffraction and interpreted in terms of residual stress. The plate, a square measuring 305mm on a side, was removed from a 6m (20-ft) diameter unirradiated boiling water reactor core shroud, and included a multipte-paas horizontal weld which joined two of the cylindrical shells which comprise the core shroud. Residual stress mapping was undertaken in the heat affected zone, concentrating on the outside half of the plate thickness. The variations in residual stresses with location appeared consistent with trends expected from case histories and from finite element calculation.