Data on the influence of low dose 400–550°C irradiation on the mechanical properties of structural steels (Types 304, 316, 316L, 316H and 316L(N) and associated weld metals) at temperatures from 20°C to 750°C, have been compiled from published literature and the results of British, Dutch, French and German laboratories. Properties evaluated include tensile, impact, creep, fatigue, and creep-fatigue. The preliminary results, which cover the dose range from 0 to 5 displacements per atom (and/or up to 9 appm helium) are presented as comparisons between irradiated and unirradiated control data, covering a range of strength and cyclic properties. The results show that low dose irradiation can have a significant influence on the properties, i.e.:• increases in tensile proof strength,• reductions in tensile ductility,• decreases in impact energy,• reductions in creep-rupture strength and ductility, and • reductions in creep-fatigue endurance.

By considering the influence of irradiation temperature and dose level, the results are rationalised in terms of irradiation hardening and grain boundary embrittlement mechanisms.