Nuclear power generation plants undergo start-up/shut-down load-temperature cycles during service operation. Components operating at temperatures in the creep regime can exhibit time dependent creep recovery during a shut-down. This behaviour is often termed anelasticity (recoverable strain) and can have a large effect on the materials performance; for example influencing remaining creep rupture life, creep ductility and creep strain rates. It is important that such effects are understood and quantified when life extensions of UK nuclear plant operating at high temperature are being assessed and justified. The objectives of the present experiment are to help understand creep behaviour at the crystal level during a start-up/shut-cycle and to reveal changes in dislocation density associated with anelastic behaviour.