Body-centered-cubic metals are used extensively as structural materials in reactor cores. However, there is a knowledge gap regarding the underlying deformation mechanisms associated with such metals under nuclear reactor conditions. An LDRD project is building atomistic-based knowledge of deformation behavior under varying conditions. The research enables scientists and engineers to better understand and predict how irradiation and inert gases may affect structural material performance in the reactor. Such a capability will extend the lifetime of existing nuclear power plants and allow improved material designs for future plants.