Strain-relief cracking is a generic creep failure mode that has been observed in many welded stainless steel structures operating at high temperatures in UK nuclear power plant. One of the challenges currently faced by nuclear utility EDF Energy is the need to predict, with high certainty, the life-time of ageing engineering plant operating in the creep regime. Following our successful studies using SANS, and having developed reliable SANS measurement procedures and a robust analysis route for heterogeneities in stainless steel, we propose using this powerful technique to probe the nature of creep cavitation associated with creep crack growth. The aim of this test will be to look for evidence of creep cavitation adjacent to the crack flanks and around the crack tip and to compare the findings with SEM observations.