Abstract: A restraint assembly for use in restraining lateral movement of a reactor core relative to a reactor vessel wherein a plurality of restraint assemblies are interposed between the reactor core and the reactor vessel in circumferentially spaced relation about the core. Each lateral restraint assembly includes a face plate urged against the outer periphery of the core by a plurality of compression springs which enable radial preloading of outer reflector blocks about the core and resist low-level lateral motion of the core. A fixed radial key member cooperates with each face plate in a manner enabling vertical movement of the face plate relative to the key member but restraining movement of the face plate transverse to the key member in a plane transverse to the center axis of the core.

Abstract: A spring pack for supporting a sprung mass relative to an unsprung mass includes a relatively low-rate spring unit and a relatively high-rate spring unit interconnected with each other and arranged between the sprung and unsprung masses, the relatively low-rate spring unit tending to respond to initial limited movement between the sprung and unsprung masses, a mechanical stop limiting the spring response of the relatively low-rate spring unit with relative movement beyond that limit tending to be absorbed by the relatively high-rate spring unit. A plurality of the spring packs are employed in a lateral restraint assembly for laterally supporting a reactor core relative to a vessel within a nuclear reactor, the relatively low-rate spring units absorbing initial multi-axial movement between the core and vessel with excessive movement of the core being absorbed by the relatively high-rate spring units.