EFFECT OF NEUTRON DOSE AND SPECTRA, HE DPA RATIO AND NI AND ZN ACCUMULATION ON IRRADIATION DAMAGE OF PURE COPPER AND PH AND DS COPPER-ALLOYS/

The present analysis is based mainly on the results of recently undert aken investigations of radiation resistance of copper alloys irradiate d in the SM-2 and BOR-60 reactors, as well as on the results of the ju st accomplished collaborative spectrally tailored experiment in the SM -2 reactor. Low-temperature radiation embrittlement at T(irr)similar t o 100 degrees C presents considerable problems for dispersion strength ened (DS) and precipitation-hardened (PH) copper alloys, as their tota l elongation at T-test=T-irr=100 degrees C drops to similar to 1% and uniform elongation to similar to 0.1%. At irradiation temperatures abo ve 300 degrees C, the most significant mechanical property change for PH copper alloys is the softening effect due to radiation enhanced pre cipitate coarsening and dislocation recovery and recrystallization pro cesses. The softening effect is sensitive to the neutron spectrum, and the threshold temperature of its manifestation in a mixed-spectrum re actor is apparently similar to 100 degrees C less than in a fast neutr on reactor. The results of copper alloys irradiation in mixed-spectrum reactors serve as the basis for an analysis of the neutron spectrum e ffect and the problem of fission-fusion correlation. At irradiation te mperatures greater than 350 degrees C, helium embrittlement associated with the high helium accumulation rate for copper alloys exposed to f usion neutrons will be one of the main problems limiting the lifetime. At increased irradiation temperatures, creep will present a special p roblem. It is apparent that the DS copper alloys have some advantage i n their radiation resistance compared to PH alloys such as CuCrZr, thi s being attributable to the high-temperature stability of their harden ing structure. (C) 1998 Elsevier Science S.A. All rights reserved.