Nuclear core positioning system

In a nuclear reactor which comprises a nuclear core including a plurality of vertically oriented elongated fuel assemblies supported in a side-by-side relationship, and wherein the assemblies are supported between an upper core plate and a lower core plate and each assembly includes nozzles which are supported within openings in said core plates for laterally positioning same;

• a radial restraint system surrounding said fuel assemblies for applying a constraining force to said nuclear core when said core is under operating conditions;
• vertically oriented resilient members positioned adjacent the core and supported at at least one end;
• load transmitting means interposed between said resilient members and the periphery of said nuclear core for transmitting resistance to displacement to said fuel assemblies as same tend to be displaced by thermal bowing and nuclear induced swelling and creep;
• a first relatively stiff band surrounding said resilient members and displaced therefrom a first predetermined distance so as to increase the resistance to displacement of said resilient member and said fuel assemblies after a small displacement of same, said band being arranged and constructed to expand only a predetermined fraction of the expansion of the core upon an increase in temperature,
• a second relatively stiff band surrounding said resilient members and displaced a second predetermined distance from said resilient members, said second predetermined distance being greater than said first predetermined distance so as to further increase resistance to displacement as greater displacements occur.