Abstract: A configurable unit cell of a core of a nuclear reactor is disclosed herein. The configurable unit cell includes a core block material and a plurality of interchangeable components configured to affect a performance parameter of the core of the nuclear reactor. The configurable unit cell further includes a plurality of channels defined within the core block material. Each channel of the plurality of channels is configured to engage an interchangeable component of the plurality of interchangeable components in an operating configuration. Each channel of the plurality of channels is separated from an adjacent channel of the plurality of channels by a predetermined pitch.

Abstract: A printed circuit heat exchanger for use in a reactor includes a core formed from a stack of plates diffusion bonded together. The core has: a top face, a bottom face disposed opposite the top face, a first side face extending between the top face and the bottom face, and a second side face disposed opposite the first side face. The printed circuit heat exchanger includes: a plurality of primary channels defined in the core, each of the primary channels extending from a primary inlet defined in the first side face to a primary outlet defined in the second side face; and a plurality of secondary channels defined in the core, each of the secondary channels extending among at least some of the primary channels from a secondary inlet defined in the top face to a secondary outlet defined in the top face.

Abstract: A printed circuit heat exchanger for use in a reactor includes a core formed from a stack of plates diffusion bonded together. The core has: a top face, a bottom face disposed opposite the top face, a first side face extending between the top face and the bottom face, and a second side face disposed opposite the first side face. The printed circuit heat exchanger includes: a plurality of primary channels defined in the core, each of the primary channels extending from a primary inlet defined in the first side face to a primary outlet defined in the second side face; and a plurality of secondary channels defined in the core, each of the secondary channels extending among at least some of the primary channels from a secondary inlet defined in the top face to a secondary outlet defined in the top face.

Abstract: A printed circuit heat exchanger for use in a reactor includes a core formed from a stack of plates diffusion bonded together. The core has: a top face, a bottom face disposed opposite the top face, a first side face extending between the top face and the bottom face, and a second side face disposed opposite the first side face. The printed circuit heat exchanger includes: a plurality of primary channels defined in the core, each of the primary channels extending from a primary inlet defined in the first side face to a primary outlet defined in the second side face; and a plurality of secondary channels defined in the core, each of the secondary channels extending among at least some of the primary channels from a secondary inlet defined in the top face to a secondary outlet defined in the top face.

Abstract: A lifting fixture for removing the upper internals from a nuclear reactor to provide access to the core during a refueling that does not require flooding of a refueling canal. A shield plate is integral to a lifting rig used to remove the upper internals. The shield plate is sized to be supported on the reactor vessel upper flange and to cover the reactor vessel opening with the closure head removed. The shield plate has openings that are in-line with the control rod assembly drive rod travel housings. Control rod assembly drive rods can be accessed through the openings. The lifting rig allows personnel to decouple the drive rods from the rod cluster control assemblies. The lifting fixture enables the decoupled drive rods to be lifted from the core with the upper internals, while shielding maintenance personnel without flooding the area above the reactor.

Abstract: A method of refueling a nuclear reactor that includes the steps of removing the reactor vessel head and upper internals to a storage location and installing a cylindrical tank having open upper and lower ends, on the reactor vessel flange. The cylindrical tank is sealed to the reactor vessel and a penetration on the side of the cylindrical tank is sealed to a refueling canal that is connected to a spent fuel pool. The level of reactor coolant within the reactor vessel is then raised to at least partially fill the cylindrical tank to a level equal to that of the spent fuel pool. The refueling canal is then opened and a refueling machine supported on the reactor vessel is employed to transfer fuel assemblies between the core and the spent fuel pool.

Abstract: A nuclear component transfer device that incorporates a shielded canister into the mast design of a conventional nuclear refueling machine. A moveable mast telescopes within a stationary mast which is attached to a bridge for lateral positioning. The canister allows for the addition of shielding that is positioned with the movement of the moveable mast without additional motorized components to deploy the shielding during nuclear component movement. The nuclear component is drawn up into the shielded canister as the moveable mast lifts the nuclear component. The nuclear component is then placed into a transfer cart that is also fitted with a shielded canister. The transfer is made without exposing the nuclear components resulting in completely shield movement.

Abstract: A combined makeup tank and passive residual heat removal system that places a tube and shell heat exchanger within the core makeup tank. An intake to the tube side of the heat exchanger is connected to the hot leg of the reactor core and the outlet of the tube side is connected to the cold leg of the reactor core. The shell side of the heat exchanger is connected to a separate heat sink through a second heat exchanger.

Abstract: A nuclear reactor having a penetration seal ring interposed between the reactor vessel flange and a mating flange on the reactor vessel head. Radial ports through the flange provide passage into the interior of the reactor vessel for utility conduits that can be used to convey signal cables, power cables or hydraulic lines to the components within the interior of the pressure vessel. A double o-ring seal is provided on both sides of the penetration flange and partial J-welds on the inside diameter of the flange between the flange and the utility conduits secure the pressure boundary.

Abstract: An integral pressurized light water reactor having most of the components of a primary side of a pressurized water reactor nuclear steam supply system housed in a single pressure vessel with a pressurizer separated from the remaining reactor system by a surge separator having multiple layers of separated steel plates with a number of concentric baffles extending therebetween. A circuitous flow path is provided through and between the plates and concentric baffles and a relatively stagnant pool of coolant is maintained within an innermost zone between the plates to provide thermal isolation.

Abstract: A method of removing the upper internals assembly from a nuclear reactor pressure vessel for refueling that simultaneously disconnects two or more of the in-core instrument thimble assemblies from the reactor vessel penetrations through which their signal cables extend. The signal cables are connected to the penetrations with an electrical connector that supports the two or more in-core instrumentation thimble assembly signal leads. Before the electrical connector is disconnected, water in the vessel is lowered below the connection so that the process is performed in a dry environment.

Abstract: A system for passively cooling nuclear fuel in a pressurized water reactor during refueling that employs gravity and alignment of valves using battery reserves or fail in a safe position configurations to maintain the water above the reactor core during reactor disassembly and refueling. A large reserve of water is maintained above the elevation of and in fluid communication with the spent fuel pool and is used to remove decay heat from the reactor core after the reaction within the core has been successfully stopped. Decay heat is removed by boiling this large reserve of water, which will enable the plant to maintain a safe shutdown condition without outside support for many days.

Abstract: A lifting fixture for removing the upper internals from a reactor to provide access to the core for refueling that does not require flooding of a refueling canal. The invention provides a means of shielding and ventilation that is integral to a lifting rig used to remove the upper internals. The lifting rig provides a means for personnel to decouple the drive rods from the rod cluster control assemblies so the drive rods can be lifted from the core with the upper internals while shielding maintenance personnel without flooding the area above the reactor.

Abstract: A nuclear component transfer device that incorporates a shielded canister into the mast design of a conventional nuclear refueling machine. A moveable mast telescopes within a stationary mast which is attached to a bridge for lateral positioning. The canister allows for the addition of shielding that is positioned with the movement of the moveable mast without additional motorized components to deploy the shielding during nuclear component movement. The nuclear component is drawn up into the shielded canister as the moveable mast lifts the nuclear component. The nuclear component is then placed into a transfer cart that is also fitted with a shielded canister. The transfer is made without exposing the nuclear components resulting in completely shield movement.

Abstract: A system for passively cooling nuclear fuel in a pressurized water reactor during refueling that employs gravity and alignment of valves using battery reserves or fail in a safe position configurations to maintain the water above the reactor core during reactor disassembly and refueling. A large reserve of water is maintained above the elevation of and in fluid communication with the spent fuel pool and is used to remove decay heat from the reactor core after the reaction within the core has been successfully stopped. Decay heat is removed by boiling this large reserve of water, which will enable the plant to maintain a safe shutdown condition without outside support for many days.

Abstract: A lifting fixture for removing the upper internals from a nuclear reactor to provide access to the core during a refueling that does not require flooding of a refueling canal. A shield plate is integral to a lifting rig used to remove the upper internals. The shield plate is sized to be supported on the reactor vessel upper flange and to cover the reactor vessel opening with the closure head removed. The shield plate has openings that are in-line with the control rod assembly drive rod travel housings. Control rod assembly drive rods can be accessed through the openings. The lifting rig allows personnel to decouple the drive rods from the rod cluster control assemblies. The lifting fixture enables the decoupled drive rods to be lifted from the core with the upper internals while shielding maintenance personnel without use of flooding the area above the reactor.

Abstract: A nuclear component transfer device that incorporates a shielded canister into the mast design of a conventional nuclear refueling machine. A moveable mast telescopes within a stationary mast which is attached to a bridge for lateral positioning. The canister allows for the addition of shielding that is positioned with the movement of the moveable mast without additional motorized components to deploy the shielding during nuclear component movement. The nuclear component is drawn up into the shielded canister as the moveable mast lifts the nuclear component. The nuclear component is then placed into a transfer cart that is also fitted with a shielded canister. The transfer is made without exposing the nuclear components resulting in completely shield movement.

Abstract: An integral pressurized water reactor that combines all of the components typically associated with a nuclear steam supply system, such as the steam generator, reactor coolant pumps, pressurizer and the reactor, into a single reactor pressure vessel. The reactor pressure vessel is itself enclosed in a containment pressure vessel that also houses a number of safety systems, such as the core make-up tanks, the primary side of residual heat removal heat exchangers, an automatic depressurization system and a recirculation system that enables continuous core cooling through natural circulation over an extended period of time. Actuation of the passive systems is done by single actuation of valves, powered from redundant batteries.

Abstract: A method of removing the upper internals assembly from a nuclear reactor pressure vessel for refueling that simultaneously disconnects two or more of the in-core instrument thimble assemblies from the reactor vessel penetrations through which their signal cables extend. The signal cables are connected to the penetrations with an electrical connector that supports the two or more in-core instrumentation thimble assembly signal leads. Before the electrical connector is disconnected, water in the vessel is lowered below the connection so that the process is performed in a dry environment.

Abstract: A system for passively cooling nuclear fuel in a pressurized water reactor during refueling that employs gravity and alignment of valves using battery reserves or fail in a safe position configurations to maintain the water above the reactor core during reactor disassembly and refueling. A large reserve of water is maintained above the elevation of and in fluid communication with the spent fuel pool and is used to remove decay heat from the reactor core after the reaction within the core has been successfully stopped. Decay heat is removed by boiling this large reserve of water, which will enable the plant to maintain a safe shutdown condition without outside support for many days.