Abstract: Nuclear reactors have very few systems for significantly reduced failure possibilities. Nuclear reactors may be boiling water reactors with natural circulation-enabling heights and smaller, flexible energy outputs in the 0-350 megawatt-electric range. Reactors are fully surrounded by an impermeable, high-pressure containment. No coolant pools, heat sinks, active pumps, or other emergency fluid sources may be present inside containment; emergency cooling, like isolation condenser systems, are outside containment. Isolation valves integral with the reactor pressure vessel provide working and emergency fluid through containment to the reactor. Isolation valves are one-piece, welded, or otherwise integral with reactors and fluid conduits having ASME-compliance to eliminate risk of shear failure. Containment may be completely underground and seismically insulated to minimize footprint and above-ground target area.

Abstract: Simplified nuclear reactors include depressurization systems or gravity-driven injection systems or both. The systems depressurize and cool the reactor without operator intervention and power. An underground containment building may be used with the depressurization and injection systems passing through the same from above ground. Depressurization systems may use a rupture disk, relief line, pool, and filter to open the reactor and carry coolant away for condensation and exhausting. Injection systems may use a coolant tank above the nuclear reactor to inject liquid coolant by gravity into the reactor through an injection line and valve. The rupture disk and valve may be integral with the reactor and use penetration seals where systems pass through containment. Rupture disks and valves can actuate passively, at a pressure setpoint or other condition, through fluidic controls, setpoint failure, etc. The depressurization system and injection system together feed-and-bleed coolant through the reactor.

Abstract: A passive containment cooling system (PCCS) condenser, for reducing some non-condensable gases in the PCCS, includes a first and a second stage condenser that each include channels in fluid communication between an inlet and an outlet header. The inlet header of the first stage condenser is configured to receive a fluid mixture through a first inlet opening. The channels are configured to condense water from the fluid mixture flowing through the channels from the inlet header to the outlet header, respectively, of the first and second stage condenser. The PCCS condenser includes a catalyst in at least one of the outlet header of the first stage condenser or the inlet header of the second stage condenser. The catalyst catalyzes a reaction for forming water from hydrogen and oxygen in the fluid mixture. The outlet header of the second stage condenser is in fluid communication with a combined vent-and-drain line.

Abstract: Nuclear reactors include isolation condenser systems that can be selectively connected with the reactor to provide desired cooling and pressure relief. Isolation condensers are immersed in a separate chamber holding coolant to which the condenser can transfer heat from the nuclear reactor. The chamber may selectively connect to an adjacent coolant reservoir for multiple isolation condensers. A check valve may permit coolant to flow only from the reservoir to the isolation condenser. A passive switch can operate the check valve and other isolating components. Isolation condensers can be activated by opening an inlet and outlet to/from the reactor for coolant flow. Fluidic controls and/or a pressure pulse transmitter may monitor reactor conditions and selectively activate individual isolation condensers by opening such flows. Isolation condenser systems may be positioned outside of containment in an underground silo with the containment, which may not have any other coolant source.

Abstract: Nuclear reactors include isolation condenser systems that can be selectively connected with the reactor to provide desired cooling and pressure relief. Isolation condensers are immersed in a separate chamber holding coolant to which the condenser can transfer heat from the nuclear reactor. The chamber may selectively connect to an adjacent coolant reservoir for multiple isolation condensers. A check valve may permit coolant to flow only from the reservoir to the isolation condenser. A passive switch can operate the check valve and other isolating components. Isolation condensers can be activated by opening an inlet and outlet to/from the reactor for coolant flow. Fluidic controls and/or a pressure pulse transmitter may monitor reactor conditions and selectively activate individual isolation condensers by opening such flows. Isolation condenser systems may be positioned outside of containment in an underground silo with the containment, which may not have any other coolant source.

Abstract: Nuclear reactors have very few systems for significantly reduced failure possibilities. Nuclear reactors may be boiling water reactors with natural circulation-enabling heights and smaller, flexible energy outputs in the 0-350 megawatt-electric range. Reactors are fully surrounded by an impermeable, high-pressure containment. No coolant pools, heat sinks, active pumps, or other emergency fluid sources may be present inside containment; emergency cooling, like isolation condenser systems, are outside containment. Isolation valves integral with the reactor pressure vessel provide working and emergency fluid through containment to the reactor. Isolation valves are one-piece, welded, or otherwise integral with reactors and fluid conduits having ASME-compliance to eliminate risk of shear failure. Containment may be completely underground and seismically insulated to minimize footprint and above-ground target area.

Abstract: A PCCS condenser may include a first and a second stage condenser. Each of the first and second stage condensers may include channels in fluid communication between an inlet and an outlet header. The inlet header of the first stage condenser may be configured to receive a fluid mixture through a first inlet opening. The channels may be configured to condense water from the fluid mixture flowing through the channels from the inlet header to the outlet header, respectively, of the first and second stage condenser. The PCCS condenser may include a catalyst in at least one of the outlet header of the first stage condenser or the inlet header of the second stage condenser. The catalyst may catalyze a reaction for forming water from hydrogen and oxygen in the fluid mixture. The outlet header of the second stage condenser may be in fluid communication with a combined vent-and-drain line.

Abstract: A method of facilitating modeling of a system includes receiving, at a processor, an extensible markup language (XML) file corresponding to a piping and instrumentation diagram (PID) of the system; identifying, by the processor, components of the system that are described in the XML file, the XML file including information about attributes of the identified components; storing, by the processor, the information about the attributes of the identified components; and generating, by the processor, a simulation model page using syntax of a simulation modeling software environment, based on the stored information about the attributes of the identified components.

Abstract: Nuclear reactors have very few systems for significantly reduced failure possibilities. Nuclear reactors may be boiling water reactors with natural circulation-enabling heights and smaller, flexible energy outputs in the 0-350 megawatt-electric range. Reactors are fully surrounded by an impermeable, high-pressure containment. No coolant pools, heat sinks, active pumps, or other emergency fluid sources may be present inside containment; emergency cooling, like isolation condenser systems, are outside containment. Isolation valves integral with the reactor pressure vessel provide working and emergency fluid through containment to the reactor. Isolation valves are one-piece, welded, or otherwise integral with reactors and fluid conduits having ASME-compliance to eliminate risk of shear failure. Containment may be completely underground and seismically insulated to minimize footprint and above-ground target area.

Abstract: Simplified nuclear reactors include depressurization systems or gravity-driven injection systems or both. The systems depressurize and cool the reactor without operator intervention and power. An underground containment building may be used with the depressurization and injection systems passing through the same from above ground. Depressurization systems may use a rupture disk, relief line, pool, and filter to open the reactor and carry coolant away for condensation and exhausting. Injection systems may use a coolant tank above the nuclear reactor to inject liquid coolant by gravity into the reactor through an injection line and valve. The rupture disk and valve may be integral with the reactor and use penetration seals where systems pass through containment. Rupture disks and valves can actuate passively, at a pressure setpoint or other condition, through fluidic controls, setpoint failure, etc. The depressurization system and injection system together feed-and-bleed coolant through the reactor.

Abstract: Nuclear reactors include isolation condenser systems that can be selectively connected with the reactor to provide desired cooling and pressure relief. Isolation condensers are immersed in a separate chamber holding coolant to which the condenser can transfer heat from the nuclear reactor. The chamber may selectively connect to an adjacent coolant reservoir for multiple isolation condensers. A check valve may permit coolant to flow only from the reservoir to the isolation condenser. A passive switch can operate the check valve and other isolating components. Isolation condensers can be activated by opening an inlet and outlet to/from the reactor for coolant flow. Fluidic controls and/or a pressure pulse transmitter may monitor reactor conditions and selectively activate individual isolation condensers by opening such flows. Isolation condenser systems may be positioned outside of containment in an underground silo with the containment, which may not have any other coolant source.

Abstract: A method of facilitating modeling of a system includes receiving, at a processor, an extensible markup language (XML) file corresponding to a piping and instrumentation diagram (PID) of the system; identifying, by the processor, components of the system that are described in the XML file, the XML file including information about attributes of the identified components; storing, by the processor, the information about the attributes of the identified components; and generating, by the processor, a simulation model page using syntax of a simulation modeling software environment, based on the stored information about the attributes of the identified components.

Abstract: Nuclear reactors have very few systems for significantly reduced failure possibilities. Nuclear reactors may be boiling water reactors with natural circulation-enabling heights and smaller, flexible energy outputs in the 0-350 megawatt-electric range. Reactors are fully surrounded by an impermeable, high-pressure containment. No coolant pools, heat sinks, active pumps, or other emergency fluid sources may be present inside containment; emergency cooling, like isolation condenser systems, are outside containment. Isolation valves integral with the reactor pressure vessel provide working and emergency fluid through containment to the reactor. Isolation valves are one-piece, welded, or otherwise integral with reactors and fluid conduits having ASME-compliance to eliminate risk of shear failure. Containment may be completely underground and seismically insulated to minimize footprint and above-ground target area.

Abstract: Nuclear fuel assembly support castings direct fluid flow through nuclear fuel assemblies with relatively lower decay ratios and thus improved flow stability. The castings include an internal flow passage that is elongated to increase fluid flow inertia. The passage may be in excess of 0.3 meters and up to several meters in a straight, vertical direction that does not disrupt inertial fluid flow. Castings may omit an entry orifice and replicate any orifice-driven pressure drop with a specifically-sized flow passage that causes a similar pressure drop, or castings may use a side or bottom entry orifice at an entrance to the passage. Castings accommodate any number of fuel assemblies and other core structures including control blades, instrumentation tubes, core plates, and other core structures, such as four fuel assemblies arranged in a grid on the casting with a cruciform control element extending through a center of the casting.

Abstract: Systems passively eliminate noncondensable gasses from facilities susceptible to damage from combustion of built-up noncondensable gasses, such as H2 and O2 in nuclear power plants, without the need for external power and/or moving parts. Systems include catalyst plates installed in a lower header of the Passive Containment Cooling System (PCCS) condenser, a catalyst packing member, and/or a catalyst coating on an interior surface of a condensation tube of the PCCS condenser or an annular outlet of the PCCS condenser. Structures may have surfaces or hydrophobic elements that inhibit water formation and promote contact with the noncondensable gas. Noncondensable gasses in a nuclear power plant are eliminated by installing and using the systems individually or in combination. An operating pressure of the PCCS condenser may be increased to facilitate recombination of noncondensable gasses therein.

Abstract: Systems passively eliminate noncondensable gasses from facilities susceptible to damage from combustion of built-up noncondensable gasses, such as H2 and O2 in nuclear power plants, without the need for external power and/or moving parts. Systems include catalyst plates installed in a lower header of the Passive Containment Cooling System (PCCS) condenser, a catalyst packing member, and/or a catalyst coating on an interior surface of a condensation tube of the PCCS condenser or an annular outlet of the PCCS condenser. Structures may have surfaces or hydrophobic elements that inhibit water formation and promote contact with the noncondensable gas. Noncondensable gasses in a nuclear power plant are eliminated by installing and using the systems individually or in combination. An operating pressure of the PCCS condenser may be increased to facilitate recombination of noncondensable gasses therein.

Abstract: Systems passively eliminate noncondensable gasses from facilities susceptible to damage from combustion of built-up noncondensable gasses, such as H2 and O2 in nuclear power plants, without the need for external power and/or moving parts. Systems include catalyst plates installed in a lower header of the Passive Containment Cooling System (PCCS) condenser, a catalyst packing member, and/or a catalyst coating on an interior surface of a condensation tube of the PCCS condenser or an annular outlet of the PCCS condenser. Structures may have surfaces or hydrophobic elements that inhibit water formation and promote contact with the noncondensable gas. Noncondensable gasses in a nuclear power plant are eliminated by installing and using the systems individually or in combination. An operating pressure of the PCCS condenser may be increased to facilitate recombination of noncondensable gasses therein.

Abstract: Systems passively eliminate noncondensable gasses from facilities susceptible to damage from combustion of built-up noncondensable gasses, such as H2 and O2 in nuclear power plants, without the need for external power and/or moving parts. Systems include catalyst plates installed in a lower header of the Passive Containment Cooling System (PCCS) condenser, a catalyst packing member, and/or a catalyst coating on an interior surface of a condensation tube of the PCCS condenser or an annular outlet of the PCCS condenser. Structures may have surfaces or hydrophobic elements that inhibit water formation and promote contact with the noncondensable gas. Noncondensable gasses in a nuclear power plant are eliminated by installing and using the systems individually or in combination. An operating pressure of the PCCS condenser may be increased to facilitate recombination of noncondensable gasses therein.

Abstract: A chimney which can be reconfigured or removed during refueling to allow vertical removal of the fuel assemblies. The chimney is designed to be collapsed or dismantled. Collapse or dismantlement of the chimney reduces the volume required for chimney storage during the refueling operation. Alternatively, the chimney has movable parts which allow reconfiguration of its structure. In a first configuration suitable for normal reactor operation, the chimney is radially constricted such that the chimney obstructs vertical removal of the fuel assemblies. In a second configuration suitable for refueling or maintenance of the fuel core, the parts of the chimney which obstruct access to the fuel assemblies are moved radially outward to positions whereat access to the fuel assemblies is not obstructed.

Abstract: A nuclear reactor is joined to a steam turbine by a main steamline for discharging steam thereto. A plurality of flow control valves regulate flow to the turbine, and a bypass valve selectively bypasses a portion of the steam around the turbine to its condenser. A pressure regulator and turbine controller are operatively joined to the control valves and the bypass valve for controlling steamflow to the turbine. An apparatus for detecting failure of one of the control valves is operatively connected to the bypass valve, and upon failure of one of the control valves to channel sufficient flowrate, the bypass valve is automatically opened to reduce reactor pressure rise. The failure detecting apparatus also provides a reduction demand signal for reducing reactor power for allowing the bypass valve to close.