Nuclear reactor system with lift-out core assembly

Abstract

A modular nuclear reactor system includes a lift-out, replaceable nuclear reactor core configured for replacement as a singular unit during a single lift-out event, such as rather than lifting and replacing individual fuel assemblies and/or fuel elements. The system includes a reactor vessel and a power generation system configured to convert thermal energy in a high temperature working fluid received from the reactor vessel into electrical energy. The reactor vessel includes: a vessel inlet and an adjacent vessel outlet arranged near a bottom on the vessel; a vessel receptacle configured to receive a unified core assembly; locating datums in the base of the vessel receptacle and configured to constrain a core assembly in multiple degrees of freedom; and an interstitial zone surrounding the vessel receptacle and housing a set of control or moderating drums.

What is claimed is: 
     
         1 . A nuclear power system, comprising:
 a reactor vessel comprising:
 a vessel inlet and a vessel outlet disposed coaxially with the vessel inlet; 
 a core receptacle defining a central axis and comprising a set of locating datums; 
 a plurality of control drums disposed about a periphery of the core receptacle, and a set of control drum actuators coupled to the set of control drums for selectively rotating the plurality of control drums; 
   a reactor core comprising:
 a lift-out support plate for vertically supporting the reactor core during insertion of the reactor core into the core receptacle and during removal of the reactor core from the core receptacle; and 
 a removable plug arranged along the central axis of the reactor vessel, the plug arranged along a central axis of the reactor core structure, the removable plug removable during refueling operations to enable a lift adapter to engage with the lift out support plate to remove the reactor core from the reactor vessel; and 
 a jacket sized for an interference fit with a moderating core structure of the reactor core at 0° C., the jacket having a greater coefficient of thermal expansion than a coefficient of thermal expansion of the moderating core structure so that the jacket is expandable to a larger size than the moderating core structure during operation, thereby creating a gap between an inner face of the jacket and an outer face of the moderating core structure to reduce stress on the moderating core structure during operation; and. 
   a spring-loaded reactor vessel head for applying a compressive force against a portion of the reactor core to allow the reactor core to selectively expand in a vertical direction while immobilizing the reactor core within the reactor vessel.   
     
     
         2 . The nuclear power system of  claim 1 , further comprising a heat exchange system comprising a helium pump connected to the vessel inlet by an input conduit and the vessel outlet by an output conduit, the helium pump configured to pump cooled helium into the vessel inlet through the input conduit and to pump heated helium from the vessel outlet through the output conduit. 
     
     
         3 . The nuclear power system of  claim 2 , the heat exchange system further comprising a supercritical carbon dioxide exchanger thermally coupled to the output conduit and configured to exchange thermal energy with the heated helium to cool the heated helium to cooled helium; and
 an extractor coupled to the supercritical carbon dioxide exchanger and configured to extract thermal energy from the supercritical carbon dioxide exchanger and to convert the thermal energy into one of heat and electricity.   
     
     
         4 . The nuclear power system of  claim 1 , the reactor core further comprising a core restraining plate for receiving the compressive force of the spring-loaded reactor vessel head. 
     
     
         5 . The nuclear power system of  claim 4 , further comprising a plurality of upper restraining pins for selectively coupling the spring-loaded reactor vessel head to the restraining plate; each of the plurality of upper restraining pins comprising a pin coupled to a spring such that in an extended position the spring causes the pin to exert a compressive immobilizing force on the restraining plate. 
     
     
         6 . The nuclear power system of  claim 5 , wherein the restraining plate comprises a plurality of alignment holes configured to receive the set of upper restraining pins; and each of the plurality of upper restraining pins defines a first cross section and each of the plurality of alignment holes defines a second cross section different than the first cross section to accommodate different rates of thermal expansion in the vessel head, the restraining plate, and the set of upper restraining pins. 
     
     
         7 . The nuclear power system of  claim 1 , wherein the lift-out support plate further comprises a set of perforations for allowing heated working fluid to exit the reactor core to an external heat exchange system. 
     
     
         8 . The nuclear power system of  claim 1 , wherein the lift out support plate further comprises an integrated connector to which an elongated member is attachable for moving the reactor core in a direction vertically with respect to the reactor vessel. 
     
     
         9 . The nuclear power system of  claim 1 , wherein the lift-out support plate includes a plurality of projections for selectively engaging a plurality of locating datum in the reactor vessel to position the reactor core within the reactor vessel. 
     
     
         10 . The nuclear power system of  claim 9 , wherein the plurality of projections and the plurality of locating datum are engageable with each other to laterally constrain the reactor core within the reactor vessel. 
     
     
         11 . A nuclear reactor core, comprising:
 a lift-out support plate for vertically supporting the reactor core during insertion of the reactor core into the core receptacle and during removal of the reactor core from the core receptacle;   a removable plug arranged along the central axis of the reactor vessel, the plug arranged along a central axis of the reactor core structure, the removable plug removable during refueling operations such that a lift adapter can engage with the lift out support plate to remove the reactor core from the reactor vessel; and   a jacket sized for an interference fit with a moderating core structure of the reactor core at 0° C., the jacket having a greater coefficient of thermal expansion than a coefficient of thermal expansion of the moderating core structure so that the jacket is expandable to a larger size than the moderating core structure during operation, thereby creating a gap between an inner face of the jacket and an outer face of the moderating core structure to reduce stress on the moderating core structure during operation.   
     
     
         12 . The nuclear reactor core of  claim 11 , the reactor core further comprising a core restraining plate for receiving compressive force of a spring-loaded reactor vessel head. 
     
     
         13 . The nuclear reactor core of  claim 12 , wherein the core restraining plate comprises a plurality of alignment holes configured to receive a set of upper restraining pins of the spring-loaded reactor vessel head. 
     
     
         14 . The nuclear reactor core of  claim 11 , wherein the lift-out support plate further comprises a set of perforations for allowing heated working fluid to exit the reactor core to an external heat exchange system. 
     
     
         14 . The nuclear reactor core of  claim 11 , wherein the lift out support plate further comprises an integrated connector to which an elongated member is attachable for moving the reactor core in a direction vertically with respect to the reactor vessel. 
     
     
         15 . The nuclear reactor core of  claim 11 , wherein the lift-out support plate includes a plurality of projections for selectively engaging a plurality of locating datum in a reactor vessel to position the reactor core within the reactor vessel. 
     
     
         16 . The nuclear reactor core of  claim 15 , wherein the plurality of projections are configured to be engageable with the plurality of locating datum to laterally constrain the reactor core within the reactor vessel. 
     
     
         17 . The nuclear reactor core of  claim 11 , further comprising a central opening for receiving a graphite plug, the graphite plug disposed in the central opening during operation of a nuclear reactor in which the nuclear reactor core is disposed, the graphite plug being removable to enable a lift adapter to be disposed within the central opening to engage an integral connector of the lift-out support plate. 
     
     
         18 . The nuclear reactor core of  claim 17 , the lift adapter coupleable to a gantry to enable the core to be moved vertically with respect to a reactor vessel of the nuclear reactor. 
     
     
         19 . The nuclear reactor core of  claim 11 , further comprising a lower reflector plate coupled to an upper surface of the lift-out support plate. 
     
     
         20 . The nuclear reactor core of  claim 12 , further comprising an upper reflector plate coupled to a lower surface of the core restraining plate.