A boiling water reactor includes a reactor building, a reactor cavity pool, a primary containment vessel, and a passive containment cooling system. The reactor building includes a top wall defining a penetration therein, a bottom wall, and at least one side wall, which define a chamber. At least a portion of the primary containment vessel is in the chamber. The passive containment cooling system includes a thermal exchange pipe including an outer pipe and an inner pipe. The outer pipe has a first outer pipe end and a second outer pipe end. The first outer pipe end is closed and in the primary containment vessel. The second outer pipe end is open and extends into the reactor cavity pool. The inner pipe has a first inner pipe end and a second inner pipe end, which are open. The second inner pipe end extends into the reactor cavity pool.

A boiling water reactor system includes a reactor vessel including a reactor core. A steam line is in communication with the reactor core and a turbine that is connected to an electrical generator. A dry standby liquid control system includes a standby vessel containing dry powder containing boron and including a high pressure water supply in communication with the standby vessel via a first closed valve, wherein the standby vessel is in communication with the reactor vessel via a second closed valve.

A boiling water reactor system includes a reactor vessel including a reactor core. A steam line is in communication with the reactor core and a turbine that is connected to an electrical generator. A dry standby liquid control system includes a standby vessel containing dry powder containing boron and including a high pressure water supply in communication with the standby vessel via a first closed valve, wherein the standby vessel is in communication with the reactor vessel via a second closed valve.

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.

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.

A long-term cooling system in a nuclear power plant according to the present disclosure may include a boundary section disposed inside a containment to enclose a reactor coolant system, and configured to restrict steam containing radioactive materials generated in the reactor coolant system from leaking into paths other than a discharge part, an In-Containment Water Storage Tank (IRWST) disposed outside the boundary section and configured to store refueling water therein, an emergency cooling tank disposed outside the containment and provided with a condensation heat exchanger, a gas-liquid separator connected to the emergency cooling tank outside the containment, and a return line configured to connect the gas-liquid separator and the boundary section such that condensate generated by condensing the steam within the boundary section through the emergency cooling tank and the gas-liquid separator is discharged toward the boundary section upon an occurrence of a nuclear power plant accident.

A long-term cooling system in a nuclear power plant according to the present disclosure may include a boundary section disposed inside a containment to enclose a reactor coolant system, and configured to restrict steam containing radioactive materials generated in the reactor coolant system from leaking into paths other than a discharge part, an In-Containment Water Storage Tank (IRWST) disposed outside the boundary section and configured to store refueling water therein, an emergency cooling tank disposed outside the containment and provided with a condensation heat exchanger, a gas-liquid separator connected to the emergency cooling tank outside the containment, and a return line configured to connect the gas-liquid separator and the boundary section such that condensate generated by condensing the steam within the boundary section through the emergency cooling tank and the gas-liquid separator is discharged toward the boundary section upon an occurrence of a nuclear power plant accident.

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.

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.

A steam separation system includes a standpipe configured to receive a gas-liquid two-phase flow stream and a diffuser configured to receive the gas-liquid two-phase flow stream from the standpipe. The diffuser includes a swirler configured to separate the gas-liquid two-phase flow stream. The swirler includes a plurality of swirler vanes and a straightener structure. The straightener structure includes a hub. The plurality of swirler vanes is mounted radially around the hub, and a straightener extends in an upward direction from the hub. The system also includes a separation barrel configured to receive the gas-liquid two-phase flow stream from the swirler. The separation barrel includes a rifled channel having orifices along an inner surface thereof. The plurality of swirler vanes is tuned with the rifled channel, such that an angle of each of the plurality of vanes corresponds to an angle of the rifled channel.