Effect of Neutron Irradiation on the Mechanical Properties of Type 348 Stainless Steel in-Pile Pressure Tubes

摘要

This report presents the results of a post-irradiation destructive examination of a Type 348 stainless steel inpile pressure tube, which was removed from the Advanced Test Reactor after exposure to a peak fluence of 3.2 x 10 exp 22 n/cm exp 2 (E > 1.0 MeV). This in-core portion of the tube operated under a hoop stress of 10,500 psi at a mean wall temperature of 725 exp 0 F. The test results indicate the occurrance of radiation saturation of the tensile, elongation, and fracture toughness properties, a reduced but adequate 800 exp 0 F creep-rupture strength, and the absence of 800 exp 0 F notch sensitivity. Radiation induced changes in density and thermal diffusivity were minimal. The material incurred an in-reactor creep of 1.8% and a concomitant stress relaxation. Transmission electron microscopy also indicates that radiation-induced lattice damage had achieved saturation.