Abstract: A nuclear steam supply system having a start-up sub-system for heating a primary coolant. In one embodiment, the invention can be a nuclear steam supply system comprising: a reactor vessel having an internal cavity, a reactor core comprising nuclear fuel disposed within the internal cavity; a steam generating vessel fluidly coupled to the reactor vessel; a primary coolant loop formed within the reactor vessel and the steam generating vessel, a primary coolant in the primary coolant loop; and a start-up sub-system fluidly coupled to the primary coolant loop, the start-up sub-system configured to: (1) receive a portion of the primary coolant from the primary coolant loop; (2) heat the portion of the primary coolant to form a heated portion of the primary coolant; and (3) inject the heated portion of the primary coolant into the primary coolant loop.

Abstract: A nuclear steam supply system having a shutdown system for removing residual decay heat generated by a nuclear fuel core. The steam supply system may utilize gravity-driven primary coolant circulation through hydraulically interconnected reactor and steam generating vessels forming the steam supply system. The shutdown system may comprise primary and secondary coolant systems. The primary coolant cooling system may include a jet pump comprising an injection nozzle disposed inside the steam generating vessel. A portion of the circulating primary coolant is extracted, pressurized and returned to the steam generating vessel to induce coolant circulation under reactor shutdown conditions. The extracted primary coolant may further be cooled before return to the steam generating vessel in some operating modes. The secondary coolant cooling system includes a pumped and cooled flow circuit operating to circulate and cool the secondary coolant, which in turn extracts heat from and cools the primary coolant.

Abstract: A nuclear steam supply system having a shutdown system for removing residual decay heat generated by a nuclear fuel core. The steam supply system may utilize gravity-driven primary coolant circulation through hydraulic-ally interconnected reactor and steam generating vessels forming the steam supply system. The shutdown system may comprise primary and secondary coolant systems. The primary coolant cooling system may include a jet pump comprising an injection nozzle disposed inside the steam generating vessel A portion of the circulating primary coolant is extracted, pressurized and returned to the steam generating vessel to induce coolant circulation under reactor shutdown conditions. The extracted primary coolant may further be cooled before return to the steam generating vessel in some operating modes. The secondary coolant cooling system includes a pumped and cooled flow circuit operating to circulate and cool the secondary coolant, which in tun extracts heat from and cools the primary coolant.

Abstract: A nuclear steam supply system having a start-up sub-system for heating a primary coolant. In one embodiment, the invention can be a nuclear steam supply system comprising: a reactor vessel having an internal cavity, a reactor core comprising nuclear fuel disposed within the internal cavity; a steam generating vessel fluidly coupled to the reactor vessel; a primary coolant loop formed within the reactor vessel and the steam generating vessel, a primary coolant in the primary coolant loop; and a start-up sub-system fluidly coupled to the primary coolant loop, the start-up sub-system configured to: (1) receive a portion of the primary coolant from the primary coolant loop; (2) heat the portion of the primary coolant to form a heated portion of the primary coolant; and (3) inject the heated portion of the primary coolant into the primary coolant loop.

Abstract: A nuclear reactor cooling system with passive cooling capabilities operable during a loss-of-coolant accident (LOCA) without available electric power. The system includes a reactor vessel with nuclear fuel core located in a reactor well. An in-containment water storage tank is fluidly coupled to the reactor well and holds an inventory of cooling water. During a LOCA event, the tank floods the reactor well with water. Eventually, the water heated by decay heat from the reactor vaporizes producing steam. The steam flows to an in-containment heat exchanger and condenses. The condensate is returned to the reactor well in a closed flow loop system in which flow may circulate solely via gravity from changes in phase and density of the water. In one embodiment, the heat exchanger may be an array of heat dissipater ducts mounted on the wall of the inner containment vessel surrounded by a heat sink.

Abstract: A fuel core for a nuclear reactor in one embodiment includes an upper internals unit and a lower internals unit comprising nuclear fuel assemblies. The assembled fuel core includes an upper core plate, a lower core plate, and a plurality of channel boxes extending therebetween. Each channel box comprises a plurality of outer walls and inner walls collectively defining a longitudinally-extending interior channels or cells having a transverse cross sectional area configured for holding no more than a single nuclear fuel assembly in some embodiments. A cylindrical reflector circumferentially surrounds channel boxes and is engaged at opposing ends by the upper and lower core plates. Adjacent cells within each channel box are formed on opposite sides of inner walls such that the cells are separated from each other by the inner walls alone without any water gaps therebetween which benefits neutronics for some small modular reactor designs.

Abstract: A passively-cooled spent nuclear fuel pool system in one embodiment includes a containment vessel comprising a thermally conductive shell and an annular reservoir surrounding the shell that holds a liquid coolant forming a heat sink. A spent fuel pool is disposed inside the containment vessel and includes a body of water in contact with a first peripheral sidewall of the fuel pool. At least one spent nuclear fuel rod submerged in the body of water heats the water. The first peripheral sidewall of the spent fuel pool is formed by a portion of the shell of the containment vessel adjacent to the fuel pool, thereby defining a shared common heat transfer wall. The heat transfer wall operates to transfer heat from the body of water in the spent fuel pool to the heat sink to cool the body of water. The heat transfer wall comprises metal in one embodiment.

Abstract: A nuclear reactor cooling system with passive cooling capabilities operable during a loss-of-coolant accident (LOCA) without available electric power. The system includes a reactor vessel with nuclear fuel core located in a reactor well. An in-containment water storage tank is fluidly coupled to the reactor well and holds an inventory of cooling water. During a LOCA event, the tank floods the reactor well with water. Eventually, the water heated by decay heat from the reactor vaporizes producing steam. The steam flows to an in-containment heat exchanger and condenses. The condensate is returned to the reactor well in a closed flow loop system in which flow may circulate solely via gravity from changes in phase and density of the water. In one embodiment, the heat exchanger may be an array of heat dissipater ducts mounted on the wall of the inner containment vessel surrounded by a heat sink.

Abstract: A passively-cooled spent nuclear fuel pool system and method therefor. In one embodiment, the invention can be a passively-cooled spent nuclear fuel pool system comprising: a spent nuclear fuel pool comprising a body of liquid water having a surface level, at least one spent nuclear fuel rod submerged in the body of liquid water that heats the body of liquid water; a lid covering the spent nuclear fuel pool to create a hermetically sealed vapor space between the surface level of the body of liquid water and the lid; and a passive heat exchange sub-system fluidly coupled to the vapor space, the passive heat exchange sub-system configured to: (1) receive water vapor from the vapor space; (2) remove thermal energy from the received water vapor, thereby condensing the water vapor to form a condensed water vapor; and (3) return the condensed water vapor to the body of liquid water.

Abstract: A passively-cooled spent nuclear fuel pool system in one embodiment includes a containment vessel comprising a thermally conductive shell and an annular reservoir surrounding the shell that holds a liquid coolant forming a heat sink. A spent fuel pool is disposed inside the containment vessel and includes a body of water in contact with a peripheral sidewall of the fuel pool. At least one spent nuclear fuel rod submerged in the body of water heats the water. The peripheral sidewall of the spent fuel pool is formed by a portion of the shell of the containment vessel adjacent to the fuel pool, thereby defining a shared common heat transfer wall. The heat transfer wall operates to transfer heat from the body of water in the spent fuel pool to the heat sink to cool the body of water. The heat transfer wall comprises metal in one embodiment.

Abstract: A nuclear steam supply system includes an elongated reactor vessel having an internal cavity with a central axis, a reactor core having nuclear fuel disposed within the internal cavity, and a steam generating vessel having at least one heat exchanger section, the steam generating vessel being fluidicly coupled to the reactor vessel. The reactor vessel includes a shell having an upper flange portion and a head having a head flange portion. The upper flange portion is coupled to the head flange portion, wherein the upper flange portion extends into the internal cavity, and the head flange portion extends outward from the internal cavity.

Abstract: A nuclear power generation system and related power cycle are disclosed, in one embodiment, the system includes primary coolant circulation through a hydraulically interconnected reactor containing nuclear fuel and a steam generating vessel collectively defining a steam supply system. Liquid secondary coolant for the power cycle flows through the steam generating vessel and is converted to steam by the primary coolant to drive a low pressure turbine of a turbine-generator set. Steam exiting the turbine is condensed and heated prior to return to the steam supply system, thereby completing a secondary coolant flow loop. In one embodiment, a majority of the secondary coolant heating occurs within the steam generating vessel via heat exchange with the primary coolant rather than externally in the secondary coolant flow loop. This creates a temperature differential between the primary and secondary coolant sufficient to create natural thermally induced convective circulation of the primary coolant.

Abstract: A passively-cooled spent nuclear fuel pool system comprising: a spent nuclear fuel pool comprising a body of liquid water having a surface level, at least one spent nuclear fuel rod submerged therein that heats the water; a lid covering the spent nuclear fuel pool to create a hermetically sealed vapor space between the surface level and the lid; and a passive heat exchange sub-system including a riser conduit comprising first and second riser inlet sections and a primary riser section that receives water vapor therefrom. Each riser inlet section has a respective inlet positioned in a respective section of the vapor space. A downcomer receives and condenses water vapor from the primary section forming condensed water vapor. A return conduit fluidly coupled to the downcomer and having an outlet located in the body of liquid water returns the condensed water vapor thereto.

Abstract: A component cooling water system for a nuclear power plant. In one embodiment, the system includes an inner containment vessel housing a nuclear reactor and an outer containment enclosure structure. An annular water reservoir is formed between the containment vessel and containment enclosure structure which provides a heat sink for dissipating thermal energy. A shell-less heat exchanger is provided having an exposed tube bundle immersed in water held within the annular water reservoir. Component cooling water from the plant flows through the tube bundle and is cooled by transferring heat to the annular water reservoir. In one non-limiting embodiment, the tube bundle may be U-shaped.

Abstract: A nuclear steam supply system includes an elongated reactor vessel having an internal cavity with a central axis, a reactor core having nuclear fuel disposed within the internal cavity, and a steam generating vessel having at least one heat exchanger section, the steam generating vessel being fluidicly coupled to the reactor vessel. The reactor vessel includes a shell having an upper flange portion and a head having a head flange portion. The upper flange portion is coupled to the head flange portion, wherein the upper flange portion extends into the internal cavity, and the head flange portion extends outward from the internal cavity. Primary coolant flow between the steam generating vessel and reactor vessel occurs via a fluid coupling comprising direct welding between forged outer nozzles of each vessel and welded inner nozzles between each vessel inside the outer nozzles.

Abstract: A system for removing thermal energy generated by radioactive materials comprising: an air-cooled shell-and-tube heat exchanger comprising a shell and plurality of heat exchange tubes arranged in a substantially vertical orientation within the shell, the plurality of heat exchange tubes comprising interior cavities that collectively form a tube-side fluid path, the shell forming a shell-side fluid path that extends from an air inlet of the shell to an air outlet of the shell, the first air inlet located at a lower elevation than the air outlet; a heat rejection closed-loop fluid circuit comprising the tube-side fluid path of the air-cooled heat exchanger, a coolant fluid flowing through the heat rejection closed-loop fluid circuit, the heat rejection closed-loop fluid circuit thermally coupled to the radioactive materials so that thermal energy generated by the radioactive materials is transferred to the coolant fluid; and the air-cooled shell-and-tube heat exchanger transferring thermal energy from the coola

Abstract: A vertical bundle air-cooled heat exchanger. In one embodiment, the invention can be a vertical bundle air-cooled condenser comprising: at least one tube bundle assembly comprising: a tube bundle comprising a plurality of finned tubes arranged in a substantially vertical and side-by-side orientation, each of the plurality of finned tubes comprising a cavity; a top header pipe comprising an inlet header cavity operably coupled to a source of steam; a bottom header pipe comprising an outlet header cavity for collecting condensate; top ends of the plurality of finned tubes coupled to the top header pipe and the bottom ends of the plurality of finned tubes coupled to the bottom header pipe; and a shell having an open top end and open bottom end, the at least one tube bundle assembly positioned within the shell.

Abstract: An autonomous self-powered system for cooling radioactive materials comprising: a pool of liquid; a closed-loop fluid circuit comprising a working fluid having a boiling temperature that is less than a boiling temperature of the liquid of the pool, the closed-loop fluid circuit comprising, in operable fluid coupling, an evaporative heat exchanger at least partially immersed in the liquid of the pool, a turbogenerator, and a condenser; one or more forced flow units operably coupled to the closed-loop fluid circuit to induce flow of the working fluid through the closed-loop fluid circuit; and the closed-loop fluid circuit converting thermal energy extracted from the liquid of the pool into electrical energy in accordance with the Rankine Cycle, the electrical energy powering the one or more forced flow units.

Abstract: A nuclear steam supply system utilizing gravity-driven natural circulation for primary coolant flow through a fluidly interconnected reactor vessel and a steam generating vessel. In one embodiment, the steam generating vessel includes a plurality of vertically stacked heat exchangers operable to convert a secondary coolant from a saturated liquid to superheated steam by utilizing heat gained by the primary coolant from a nuclear fuel core in the reactor vessel. The secondary coolant may be working fluid associated with a Rankine power cycle turbine-generator set in some embodiments. The steam generating vessel and reactor vessel may each be comprised of vertically elongated shells, which in one embodiment are arranged in lateral adjacent relationship. In one embodiment, the reactor vessel and steam generating vessel are physically discrete self-supporting structures which may be physically located in the same containment vessel.

Abstract: An autonomous self-powered system for cooling radioactive materials comprising: a pool of liquid; a closed-loop fluid circuit comprising a working fluid having a boiling temperature that is less than a boiling temperature of the liquid of the pool, the closed-loop fluid circuit comprising, in operable fluid coupling, an evaporative heat exchanger at least partially immersed in the liquid of the pool, a turbogenerator, and a condenser; one or more forced flow units operably coupled to the closed-loop fluid circuit to induce flow of the working fluid through the closed-loop fluid circuit; and the closed-loop fluid circuit converting thermal energy extracted from the liquid of the pool into electrical energy in accordance with the Rankine Cycle, the electrical energy powering the one or more forced flow units.