Patent Number: 
Section: claims

1. An apparatus comprising:a pressure vessel comprising an upper vessel section and a lower vessel section;a nuclear reactor core comprising fissile material disposed the lower vessel section;a suspended support assembly that is suspended from the pressure vessel, including a plurality of hanger plates connected by tie rods, the plurality of hanger plates including a mid-hanger plate that is disposed between an upper hanger plate and a lower hanger plate; andupper internals disposed in the lower vessel section above the nuclear reactor core and mounted on the suspended support assembly, the upper internals including at least guide frames and internal control rod drive mechanisms (CRDMs) with CRDM motors;the internal CRDMs being disposed between the mid-hanger plate and the upper hanger plate, the guide frames being disposed below the mid-hanger plate, the mid-hanger plate engaging both the internal CRDMs and the guide frames. 2. The apparatus of claim 1, wherein the internal CRDMs are bottom supported by the mid-hanger plate. 3. The apparatus of claim 2, wherein the guide frames are top supported by the mid-hanger plate and hang below the mid-hanger plate. 4. The apparatus of claim 2, wherein the guide frames are bottom supported by the lower hanger plate that is disposed below the mid-hanger plate. 5. The apparatus of claim 4, wherein the mid-hanger plate provides lateral support for the guide frames. 6. The apparatus of claim 1, wherein the guide frames are top supported by the mid-hanger plate and hang below the mid-hanger plate. 7. The apparatus of claim 1, wherein the mid-hanger plate supports or includes a power distribution plate that distributes electrical power to the internal CRDMs. 8. The apparatus of claim 1, wherein the mid-hanger plate includes openings, each opening aligned with one internal CRDM and one guide frame. 9. The apparatus of claim 1, wherein:the upper hanger plate is disposed above the mid-hanger plate and engages the internal CRDMs but not the guide frames; andthe lower hanger plate is disposed below the mid-hanger plate and engages the guide frames but not the internal CRDMs. 10. The apparatus of claim 9, wherein the plurality of hanger plates consists of only said upper hanger plate, said mid-hanger plate, and said lower hanger plate. 11. An apparatus comprising:upper internals configured to be disposed as a unit in a pressure vessel of a nuclear reactor, the upper internals including:a suspended support assembly suspended from the pressure vessel, including a plurality of hanger plates connected by tie rods, the hanger plates including a mid-hanger plate, an upper hanger plate disposed above the mid-hanger plate, and a lower hanger plate disposed below the mid-hanger plate;guide frames mounted to the mid-hanger plate and the lower hanger plate; andinternal control rod drive mechanisms (CRDMs) with CRDM motors, the internal CRDMS mounted between the mid-hanger plate and the upper hanger plate. 12. The apparatus of claim 11, wherein the internal CRDMs are bottom supported by the mid-hanger plate and are laterally supported by the upper hanger plate. 13. The apparatus of claim 12, wherein the guide frames are top supported by the mid-hanger plate and hang below the mid-hanger plate, and are laterally supported by the lower hanger plate. 14. The apparatus of claim 12, wherein the guide frames are bottom supported by the lower hanger plate and the mid-hanger plate laterally supports the guide frames. 15. The apparatus of claim 11, wherein the guide frames are top supported by the mid-hanger plate and hang below the mid-hanger plate, and are laterally supported by the lower hanger plate. 16. The apparatus of claim 11, wherein the upper internals further include a distribution plate supported by the mid-hanger plate, the distribution plate configured to distribute electrical power to the internal CRDMs. 17. The apparatus of claim 11, wherein the mid-hanger plate includes openings, each opening aligned with one internal CRDM and one guide frame. 18. The apparatus of claim 11, further comprising a flange, the suspended support assembly of the upper internals being suspended from the flange.