Patent Number: 062333003
Section: claims

1. A shroud head to top guide interface in a nuclear reactor comprising a top guide flange, and a shroud head flange configured to couple to said top guide flange, said top guide flange comprising a plurality of frusto-conical shaped guide pins extending from a top surface of said top guide flange, each said frusto-conical guide pin comprising a first base and a second base, said first base having a larger diameter than said second base, said first base of said frusto-conical guide pins located adjacent said top surface of said top guide flange, said shroud head flange comprising a plurality of guide pin openings, each said guide pin opening comprising a frusto-conical shaped portion configured to receive a corresponding frusto-conical shaped guide pin. 2. An interface in accordance with claim 1 wherein a bottom surface of said shroud head flange is in surface to surface contact with said top surface of said top guide flange. 3. An interface in accordance with claim 2 wherein each guide pin opening is defined by an inside surface of said shroud head flange, each said inside surface defining said guide pin opening comprises a frusto-conical portion, said frusto-conical portion opening includes a large base and a small base, and extends from said bottom surface of said shroud head flange. 4. An interface in accordance with claim 3 wherein each guide pin opening further comprises a cylindrical portion, said cylindrical portion extending from said small base of said frusto-conical portion to a top surface of said shroud head flange. 5. An interface in accordance with claim 3 wherein a slope of said inside surface of said shroud head flange defining each said guide pin opening is configured to be equal to a slope of said frusto-conical guide pins. 6. An interface in accordance with claim 5 wherein a diameter of said large base of each said guide pin opening is configured to be larger than a diameter of said large base of each said frusto-conical guide pin so that there is a clearance of less than about 1.0 millimeter between each said inside surface of said shroud head defining said guide pin opening and each said guide pin when the shroud head flange is positioned in surface to surface contact with said top guide flange. 7. An interface in accordance with claim 5 wherein a diameter of said large base of each said guide pin opening is configured to be larger than a diameter of said large base of each said frusto-conical guide pin so that there is a clearance of less than about 0.8 millimeter between each said inside surface of said shroud head defining said guide pin opening and each said guide pin when the shroud head flange is positioned in surface to surface contact with said top guide flange. 8. An interface in accordance with claim 5 wherein each said frusto-conical guide pin comprises a cone angle of between about 20 to 80 degrees. 9. An interface in accordance with claim 8 wherein each said frusto-conical guide pin comprises a cone angle of between about 55 to 65 degrees. 10. A shroud for a nuclear reactor comprising a top guide and a shroud head, said top guide comprising a flange, said shroud head comprising a flange configured to couple to said top guide flange, said top guide flange comprising a plurality of frusto-conical shaped guide pins extending from a top surface of said top guide flange, each said frusto-conical guide pin comprising a first base and a second base, said first base having a larger diameter than said second base, said first base of said frusto-conical guide pins located adjacent said top surface of said top guide flange, said shroud head flange comprising a plurality of guide pin openings, each said guide pin opening comprising a frusto-conical shaped portion configured to receive a corresponding frusto-conical shaped guide pin. 11. A shroud in accordance with claim 10 wherein a bottom surface of said shroud head flange is in surface to surface contact with said top surface of said top guide flange. 12. A shroud in accordance with claim 11 wherein each guide pin opening is defined by an inside surface of said shroud head flange, each said inside surface defining said guide pin opening comprises a frusto-conical portion, said frusto-conical portion includes a large base and a small base, and extends from said bottom surface of said shroud head flange. 13. A shroud in accordance with claim 12 wherein each guide pin opening further comprises a cylindrical portion, said cylindrical portion extending from said small base of said frusto-conical portion to a top surface of said shroud head flange. 14. A shroud in accordance with claim 12 wherein a slope of said inside surface of said shroud head flange defining each said guide pin opening is configured to be equal to a slope of said frusto-conical guide pins. 15. A shroud in accordance with claim 14 wherein a diameter of said large base of each said guide pin opening is configured to be larger than a diameter of said large base of each said frusto-conical guide pin so that there is a clearance of less than about 1.0 millimeter between each said inside surface of said shroud head defining said guide pin opening and each said guide pin when the shroud head flange is positioned in surface to surface contact with said top guide flange. 16. A shroud in accordance with claim 14 wherein a diameter of said large base of each said guide pin opening is configured to be larger than a diameter of said large base of each said frusto-conical guide pin so that there is a clearance of less than about 0.8 millimeter between each said inside surface of said shroud head defining said guide pin opening and each said guide pin when the shroud head flange is positioned in surface to surface contact with said top guide flange. 17. A shroud in accordance with claim 14 wherein each said frusto-conical guide pin comprises a cone angle of between about 20 to 80 degrees. 18. A shroud in accordance with claim 17 wherein each said frusto-conical guide pin comprises a cone angle of between about 55 to 65 degrees. 19. A shroud for a nuclear reactor comprising a top guide and a shroud head, said top guide comprising a flange, said shroud head comprising a flange configured to couple to said top guide flange, said shroud head flange comprising a plurality of frusto-conical shaped guide pins extending from a bottom surface of said shroud head flange, each said frusto-conical guide pin comprising a first base and a second base, said first base having a larger diameter than said second base, said first base of said frusto-conical guide pins located adjacent said bottom surface of said shroud head flange, said top guide flange comprising a plurality of guide pin openings, each said guide pin opening comprising a frusto-conical shaped portion configured to receive a corresponding frusto-conical shaped guide pin. 20. A shroud in accordance with claim 19 wherein said bottom surface of said shroud head flange is in surface to surface contact with a top surface of said top guide flange. 21. A shroud for a nuclear reactor comprising a top guide and a shroud head, said top guide comprising a flange, said shroud head comprising a flange configured to couple to said top guide flange, said top guide flange comprising a plurality of frusto-conical shaped guide pins extending from a top surface of said top guide flange, and said shroud head flange comprising a plurality of frusto-conical shaped guide pins extending from a bottom surface of said shroud head flange, each said frusto-conical guide pin comprising a first base and a second base, said first base having a larger diameter than said second base, said first base of said frusto-conical guide pins extending from said shroud head flange located adjacent said bottom surface of said shroud head flange, said first base of said frusto-conical guide pins extending from said top guide flange located adjacent said top surface of said top guide flange, and said shroud head flange comprising a plurality of guide pin openings, each said guide pin opening comprising a frusto-conical shaped portion configured to receive a corresponding frusto-conical shaped guide pin, and said top guide flange comprising a plurality of guide pin openings, each said guide pin opening comprising a frusto-conical shaped portion configured to receive a corresponding frusto-conical shaped guide pin. 22. A shroud in accordance with claim 21 wherein said bottom surface of said shroud head flange is in surface to surface contact with said top surface of said top guide flange.