Abstract: An in-core restraint assembly is for a nuclear reactor core including an upper core plate, a lower core support plate and a plurality of fuel assemblies extending longitudinally therebetween. Each fuel assembly includes top and bottom nozzles and a plurality of elongated fuel rods extending therebetween. The in-core restraint assembly includes a first restraint element, such as a spring pack, coupled to the upper core support plate and providing a substantially axial compressive force on the top nozzle of the fuel assembly. An optional second restraint element is structured to be coupled to the lower core plate in order to engage and further restrain the fuel assembly proximate the bottom nozzle. The second restraint element includes a pin member extending from the bottom nozzle of the fuel assembly and received in a socket coupled to the lower core support plate, whereby this mating sustains a longitudinal (vertical) frictional force which must be overcome before fuel assembly lift off can occur.