The performance of cold-worked Zircaloy 2 reactor pressure tubes has been assessed by destructive tests of tubes irradiated under CANDU-PHW power reactor conditions of temperature (240 to 280 C), stress (10,500 to 17,200 psi), and neutron irradiation. Reactor service increases biaxial burst strength, accompanied by a change in deformation mode that leads to reduced ductility after irradiation. Crack tolerance of the tubing is virtually unaffected by reactor service, and the critical crack length exceeds 3 in. (75 mm) at 16,000 psi (11.3 kg/mm²) hoop stress and 300 C.

Uniaxial tension tests indicate that operating stress reduces the transverse tensile strength of unirradiated tubing. Irradiation strengthening appears to be direction dependent, suggesting a possible influence of operating stress on the distribution of irradiation damage. Transmission electron microscopy shows the damage to be in the form of discrete dislocation loops.

Oxidation rate in water is enhanced by neutron irradiation but is acceptably low, as is hydrogen/deuterium pickup. Diameter measurements support the evidence from in-pile creep investigations that creep rate partly depends on fast neutron flux.