Impact property degradation of ferritic/martensitic steels after the fast reactor irradiation ‘ARBOR 1’

In an energy generating fusion reactor, structural materials will be exposed to very high levels of irradiation damage of about 100 dpa. These damage conditions can be realized – in reasonable times – only in fast reactors. For this purpose a cooperation between Forschungszentrum Karlsruhe and State Scientific Centre of Russian Federation Research Institute of Atomic Reactors had been implemented. The irradiation project is named ‘ARBOR 1’ (Latin for tree). Impact, tensile and low cycle fatigue specimens of reduced activation ferritic/martensitic steels, e.g. EUROFER 97, F82H mod., OPTIFER IVc, EUROFER 97 with different boron contents and ODS-EUROFER 97 have been irradiated in a fast neutron flux of 1.8 × 1015 n/cm2 s (>0.1 MeV) at a temperature <340 °C up to ∼30 dpa. In the post irradiation impact tests a dramatic increase in the ductile to brittle transition temperature as an effect of irradiation has been detected.