44 research outputs found
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Tensile property changes of metals irradiated to low doses with fission, fusion and spallation neutrons
Radiation effects due to low doses of spallation neutrons are compared directly to those produced by fission and fusion neutrons. Yield stress changes of pure Cu, alumina-dispersion-strengthened Cu and AISI 316 stainless steel irradiated at 36--55{degrees}C in the Los Alamos Spallation Radiation Effects Facility (LASREF) are compared with earlier results of irradiations at 90{degrees}C using 14 MeV D-T fusion neutrons at the Rotating Target Neutron Source and fission reactor neutrons in the Omega West Reactor. At doses up to 0.04 displacements per atom (dpa), the yield stress changes due to the three quite different neutron spectra correlate well on the basis of dpa in the stainless steel and the Cu alloy. However, in pure Cu, the measured yield stress changes due to spallation neutrons were anomalously small and should be verified by additional irradiations. With the exception of pure Cu, the low dose, low temperature experiments reveal no fundamental differences in radiation hardening by fission, fusion or spallation neutrons when compared on the basis of dpa
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Correlation of mechanical property changes in neutron irradiated pressure vessel steels on the basis of spectral effects
Defect production functions derived from atomistic modeling were evaluated for use in correlating yield stress changes of A212B and A302B pressure vessel steels irradiated in a wide variety of neutron spectra at low temperatures (40--90{degree}C) and low doses (<0.1 dpa). The irradiations were performed in RTNS-II, OWR, ORR and the HFIR pressure vessel surveillance positions. The data from RTNS-II, OWR and ORR are correlated fairly well on the basis of dpa, but the data from HFIR show that only one tenth as many dpa are needed to produce the same radiation-induced yield stress changes as in the other neutron spectra. About 96% of the neutrons in the HFIR surveillance position are thermal neutrons, and a significant fraction of the displacements is produced by recoils from thermal neutron captures. The best correlation of all the data is achieved when the property changes are compared on the basis of the production of freely migrating self-interstitial defects, which better represents the defects participating in the radiation strengthening process