The subsurface radioactive disposal site located at the Idaho National Laboratory contains neutron-activated metals from non-fuel nuclear-reactor-core components. A long-term corrosion study is being conducted to obtain site-specific corrosion rates to support efforts to more accurately estimate the transfer of activated elements in an arid vadose zone environment. The study uses non-radioactive metal coupons representing the prominent neutron-activated material buried at the disposal location namely two types of stainless steels nickel-chromium steel alloy zirconium alloy beryllium and aluminum. Additionally carbon steel (the material used in cask disposal liners and other disposal containers) and duplex stainless steel (proposed for high-integrity containers) are also included in the study. This paper briefly describes the test program and presents the corrosion rate results through twelve years of underground exposure. Key words: beryllium aluminum zirconium duplex stainless steel stainless steel neutron-activated metals nuclear reactor components underground corrosion microbiologically induced corrosion arid vadose zone.