Patent Number: 
Section: claims

1. A system for attenuating seismic forces in a nuclear reactor module comprising an inner nuclear reactor pressure vessel surrounded by an outer containment vessel, the outer containment vessel including a first portion and a second portion detachably connected to and extending above a top end of the first portion, and containment vessel extensions extending outward from an outside surface of the outer containment vessel, the system comprising:a reactor building comprising a reactor building floor; anda support structure securely connected to the reactor building floor, wherein the support structure comprises:a receiving structure including walls extending up from the reactor building floor along an outside of the first portion of the outer containment vessel and at least partially surrounding the first portion of the outer containment vessel, anda retention system comprising support members extending inward from an inner surface of the walls of the receiving structure, whereindistal ends of the support members are spaced apart and disconnected from the outer containment vessel and configured to contact the outer containment vessel during a seismic event, and wherein pairs of the support members extend along opposite lateral sides of the containment vessel extensions. 2. The system of claim 1, wherein an elevation of the support members above the reactor building floor is less than one-half an overall height of the outer containment vessel, and wherein the second portion of the outer containment vessel extends above the retention system without contacting the support structure during the seismic event. 3. The system of claim 2, wherein the support members are configured to restrict a circumferential rotation of the containment vessel about its longitudinal axis and restrict a radial movement of the containment vessel towards the walls of the receiving structure. 4. The system of claim 1, wherein the first portion of the outer containment vessel is detachably connected to the second portion of the outer containment vessel by a flange, and wherein the retention system is configured to contact the flange during the seismic event. 5. The system of claim 1, wherein the reactor module comprises a base support that rests on the reactor building floor, and wherein the support structure is configured to at least partially surround the lower portion of the reactor module without contacting the base support. 6. The system of claim 5, wherein the base support is not securely connected to the reactor building floor, wherein the reactor module is configured to tilt within the support structure during the seismic event, and wherein the retention system is configured to contact the lower portion of the reactor module when the reactor module tilts. 7. The system of claim 1 wherein the one or more support members are configured to contact the second portion of the outer containment vessel during the seismic event. 8. The system of claim 7, wherein the one or more support members are located near a steam generator connection that passes through the outer containment vessel. 9. The system of claim 7, wherein an elevation of the one or more support members above the reactor building floor is greater than or equal to one-half an overall height of the reactor module, and wherein the second portion of the outer containment vessel extends above the one or more support members. 10. The system of claim 9, wherein the elevation of the one or more support members is two-thirds of the overall height of the reactor module, and wherein a length of the second portion of the outer containment vessel is one-third of the overall height of the reactor module. 11. A support structure for attenuating seismic forces in one or more nuclear reactor modules housed in a reactor building, wherein at least some of the nuclear reactor modules comprise an inner nuclear reactor pressure vessel surrounded by an outer containment vessel, the outer containment vessel includes a first portion and a second portion detachably connected to and extending above a top end of the first portion, and a containment vessel extension extends outward from an outside surface of the outer containment vessel, the support structure comprising:a receiving structure including walls extending up from a floor of the reactor building and at least partially surrounding the first portion of the outer containment vessel, anda retention system comprising a support member located near a top inner surface of one of the walls of the receiving structure, wherein:a distal end of the support member is spaced and disconnected from the outer containment vessel and the support member extends along a lateral side of the containment vessel extension;the support member is configured to contact the outer containment vessel during a seismic event and to restrict a radial movement of the outer containment vessel; andthe support member is configured to contact the lateral side of the containment vessel extension during the seismic event and restrict a circumferential rotation of the outer containment vessel. 12. The support structure of claim 11, further comprising:a first receiving structure configured to receive a first reactor module housed in the reactor building;a second receiving structure configured to receive a second reactor module housed in the reactor building; anda ligament structure that connects the first receiving structure to the second receiving structure, wherein the ligament structure is configured to maintain a minimum spacing between the first reactor module and the second reactor module. 13. The support structure of claim 12, wherein the retention system is configured to allow the first reactor module to be removed from the support structure without removing the second reactor module. 14. The support structure of claim 11, wherein the first portion of the outer containment vessel is removably connected to the second portion of the outer containment vessel at a flange. 15. The support structure of claim 11, wherein the receiving structure comprises a recessed space sized to fit the first portion of the outer containment vessel that is lowered into the support structure. 16. The support structure of claim 15, wherein the recessed space forms a substantially cylindrical shaped receiving area that extends from a top surface of the receiving structure to the floor of the reactor building. 17. The support structure of claim 15, wherein the recessed space is formed by five or more contiguous walls of the receiving structure. 18. The support structure of claim 15, wherein the receiving structure walls extend around three sides of the outer containment vessel. 19. A support structure for attenuating seismic forces on a nuclear reactor module housed in a reactor building having a floor, the nuclear reactor module including an inner nuclear reactor pressure vessel surrounded by an outer containment vessel, and the outer containment vessel including a first portion and a second portion detachably connected to and extending above a top end of the first portion, and containment vessel extensions extending radially outward from the outer containment vessel, the support structure comprising:a base structure supporting the nuclear reactor module on the reactor building floor;walls surrounding at least partially the first portion of the outer containment vessel and extending up from the reactor building floor; andmultiple pairs of spaced apart support members, each pair extending out from one of the walls with the support members of each pair extending along opposite lateral sides of the containment vessel extensions, wherein each of the support members:have distal ends spaced apart and disconnected from the outer containment vessel and configured to contact the outer containment vessel during a seismic event and restrict a radial movement of the outer containment vessel; andare further configured to contact the lateral sides of the containment vessel extensions during the seismic event and restrict a circumferential rotation of the outer containment vessel. 20. The apparatus of claim 19, wherein an elevation of the support members is located at an elevation above the reactor building floor equal to or less than one-half of an overall height of the outer containment vessel, and wherein the second portion of the outer containment vessel extends above the support members without contacting the support structure during the seismic event.