Impact of Kr and Ar seeding on D retention in ferritic-martensitic steels after high-fluence plasma exposure

•Kr and Ar seeding of D plasma did not result in the formation of new D trapping sites in RAFM steel Eurofer’97 and commercial steel P92.•The majority of the retained D was trapped in the steel bulk, irrespective of the substantial surface damage by ion impact and effective removal by Kr and Ar sputtering.•D desorption from the bulk material of the ferritic-martensitic steels after Kr/Ar-seeded plasma exposures exhibits lower, but similarly positioned desorption peaks as after pure D exposures.•Kr causes more intensive steel sputtering than Ar, and therefore results in much less D retention.