In the present paper, the use of small angle neutron scattering to study creep cavitation around reheat cracking in two 316H austenitic stainless steel header components is reported. The components had been removed after long time high temperature operation in nuclear power plants. Cavities up to 350 nm in size are quantified, and their distribution relative to the crack, near the crack origin and away from the crack tip along the crack direction, is measured. Cavitation increases significantly on approaching the crack near the crack mouth. Cavitation is less prominent near the crack tip with minimal variation away from the crack tip. More extensive cavitation near the crack is found in the component with the longer reheat crack.