Research metallurgist, Corporate Research and Development Center, General Electric CompanyVallecitos Nuclear Center, SchenectadyPleasanton, N.Y.Calif
Pages: 16 Published: Jan 1977
A laboratory testing method which is capable of imposing plane-stress and localized plane-strain loading conditions on tubing specimens was used to examine effects of annealing temperature and test environment on the strength and ductility of neutron irradiated Zircaloy-2 tubing. Tests were performed at 350°C in both air and iodine environments on specimens previously irradiated at 327°C in a helium atmosphere to fluences ranging between 1.26 and 1.60 × 1021 neutrons (n)/cm2 (E > 1 MeV). The tensile ductility under plane-strain loading conditions depended on preirradiation annealing temperature, with recrystallized specimens showing the largest plastic strain at maximum load (6 to 10 percent) in air. By way of comparison, stress-relieved specimens showed the largest plastic strain at maximum load (4 to 5 percent) under conditions of plane-stress loading in air. An iodine environment reduced the load-carrying capacity of the cladding (plane-strain loading) and lowered the strain at maximum load to near the detection limit of the test technique (approximately 1 percent), regardless of prior heat treatment. A change in failure mode from dimpled ductile rupture to quasicleavage and fluting accompanied this loss of ductility.
zirconium, mechanical properties, irradiation, zirconium alloys, iodine, stress corrosion, plastic instability, localized deformation, cladding properties
Paper ID: STP35591S