The effects of residual elements on the service behavior of austenitic stainless steels in present reactor systems are reviewed with respect to alloy stability in the temperature ranges for current and advanced reactor concepts. The stringent demands on these alloys in advanced reactor systems, which require long service life of stressed components under combined neutron flux, high temperature, and reactive coolant environments, are outlined. Changes in phase stability and precipitation reactions caused by atomic displacements at relatively low temperatures are discussed from the background of current neutron damage theory. High temperature nonrecoverable embrittlement of these alloys is described in terms of both carbide precipitation and helium generation mechanisms. Thermal-mechanical treatments have been found to be successful in reducing the magnitude of this embrittlement. In the case of fast breeder reactors, neutronic reactions will cause a significant change in some alloy constituents and will cause the generation of helium and hydrogen gaseous products. Theoretical studies which have considered both the types of structural damage resulting from these neutronic effects in different neutron spectra and the resulting effects of this damage on metallurgical behavior are discussed.