The effects of displacement damage, plasma exposure and heat loads on T retention in reduced-activation ferritic/martensitic (RAFM) steels were investigated by exposing the steels to DT gas at 473 K. Despite enormous change in surface morphology, T retention in the heat-loaded specimen was comparable with that in the unloaded specimen. The exposure to plasma resulted in a drastic increase in T retention at the surface and/or sub surface. However, the T trapped at the surface/subsurface was easily removed by maintaining the specimens in air at ∼300 K. Formation of radiation-induced defects led to a significant increase in T retention, and T trapped in the defects was not removed at ∼300 K. These observations suggest that displacement damages have the largest effects on T retention at ∼473 K.