Longitudinal tension specimens fabricated from a reactor-operated pressure tube that had experienced 3.6 effective full power years of operation when tested at 573 K showed increases in the yield and tensile strength of 39 and 30%, respectively. The residual uniform elongation was 1.8%. The irradiation-induced tensile property changes were observed to be lower than those reported in unstressed tension specimens.
Reactor-operated garter springs which had also experienced 3.6 effective full power years of operation were subjected to load extension tests up to 9 kg of load. These springs exhibited lower residual extension at all loads up to 9 kg as compared to unirradiated springs and retained adequate spring properties. The girdle wires had uniform elongation of 4% typical.
Half-size Charpy specimens of end shield material were evaluated for increases in nil ductility transition temperature (NDTT) and dynamic fracture toughness (KId), after irradiating the specimens at a temperature lower than 423 K in a CIRUS test reactor to fluence levels of 1.5, 7, and 14 × 1019 n/cm2 (> 1 MeV). A saturation trend in NDTT was observed beyond the fluence level of 7 × 1019 n/cm2. KId values evaluated at 338 K were 44.7, 39.0, and 30.1 MPa√m for the three fluence levels studied.