Gamma-ray (electron) irradiation effects on tensile properties of ferritic alloys

We demonstrate that high-energy electron irradiation can be used to study gamma-ray embrittlement of reactor pressure vessels. Observed changes in tensile properties, in ferritic alloys electron irradiated at low temperature (less than or equal to 50 degrees C), correlate well with neutron irradiation data when compared simply on a displacement per atom basis. The similarity in embrittlement behavior between gamma-rays (electrons) and neutrons can be explained in terms of a reaction-rate theory model of defect production and clustering. The present results, obtained under well-controlled experimental conditions, provide strong support for a previous analysis implicating gamma-ray damage as the source of the ''accelerated'' embrittlement of the High Flux Isotope Reactor (HFIR) pressure vessel.