Provided are a system and method for reducing the atmospheric release of radioactive materials caused by a severe accident. The system includes a steam generator disposed in a containment building, configured to generate steam by using heat of a coolant heated in a nuclear reactor, and connected to a turbine through a main steam line, a decontamination tank connected to the main steam line through a connection line and containing decontamination water for decontaminating the steam delivered from the steam generator and reducing atmospheric release of radioactive materials when a severe accident occurs, and a depressurizing power generation unit disposed on the connection line and configured to generate emergency power while depressurizing the steam delivered from the steam generator toward the decontamination tank when the severe accident occurs.

A safety injection device includes, a cooling water storage section accommodating cooling water injected into the reactor coolant system, a power producing section producing power with steam discharged from the reactor coolant system in case of an accident, a steam supply pipe transmitting steam discharged from the reactor coolant system to the power producing section, a steam discharge pipe discharging steam used to drive the power producing section and a safety injection line supplying cooling water accommodated in the cooling water storage section to the inside of the reactor coolant system. In addition, cooling water accommodated in the cooling water storage section is supplied to the inside of the reactor coolant system, based on the power produced by the power producing section, through a cooling water inlet pipe connecting the cooling water storage section and the power producing section.

A nuclear reactor is designed to couple the load path of the control elements with the reactor core, thus reducing the opportunity for differential movement between the control elements and the reactor core. A cartridge core barrel can be fabricated in a manufacturing facility to include the reactor core, control element supports, and control element drive system. The cartridge core barrel can be mounted to a reactor vessel head, and any movement, such as through seismic forces, transmits an equal direction and magnitude to the control elements and the reactor core, thus inhibiting the opportunity for differential movement.

A generator is installed on and provides electrical power from a turbine by converting the turbine's mechanical energy to electricity. The generated electrical power is used to power controls of the turbine so that the turbine can remain in use through its own energy. The turbine can be a safety-related turbine in a nuclear power plant, such that, through the generator, loss of plant power will not result in loss of use of the turbine and safety-related functions powered by the same. Appropriate circuitry and electrical connections condition the generator to work in tandem with any other power sources present, while providing electrical power with properties required to safely power the controls.

A nuclear reactor is configured with an intermediate coolant loop for transferring thermal energy from the reactor core for a useful purpose. The intermediate coolant loop includes a bypass flowpath with an air heat exchanger for dumping reactor heat during startup and/or shutdown. A fluidic diode along the bypass flowpath asymmetrically restricts flow across the bypass flowpath, inhibiting flow in a first flow direction during a full power operating condition and allowing a relatively uninhibited flow in a second direction during a startup and/or shut down low power operating condition.

A reactor cooling and power generation system according to the present disclosure includes a reactor vessel, a heat exchange section formed to receive heat generated from a core inside the reactor vessel, from a feedwater system through a fluid, and an electric power production section. A Stirling engine is provided to produce electric energy using the energy of the fluid whose temperature has increased while receiving the heat of the reactor. The system is formed to circulate the fluid that has received heat from the core in the heat exchange section through the electric power production section. The system operates even during a normal operation and during an accident of the nuclear power plant. The reactor cooling and power generation system accompanies a nuclear reactor vessel which includes a reactor coolant system, a feedwater system and a steam generator. A turbine produces electric power from the feed water system.

A nuclear reactor is designed to couple the load path of the control elements with the reactor core, thus reducing the opportunity for differential movement between the control elements and the reactor core. A cartridge core barrel can be fabricated in a manufacturing facility to include the reactor core, control element supports, and control element drive system. The cartridge core barrel can be mounted to a reactor vessel head, and any movement, such as through seismic forces, transmits an equal direction and magnitude to the control elements and the reactor core, thus inhibiting the opportunity for differential movement.

A nuclear reactor is configured with an intermediate coolant loop for transferring thermal energy from the reactor core for a useful purpose. The intermediate coolant loop includes a bypass flowpath with an air heat exchanger for dumping reactor heat during startup and/or shutdown. A fluidic diode along the bypass flowpath asymmetrically restricts flow across the bypass flowpath, inhibiting flow in a first flow direction during a full power operating condition and allowing a relatively uninhibited flow in a second direction during a startup and/or shut down low power operating condition.

A nuclear reactor is configured with a primary coolant loop for transferring heat away from the nuclear reactor core. In a shutdown event, the primary coolant pump may stop pumping primary coolant through the reactor core, resulting in decay heat buildup within the reactor core. An inertial energy coast down system can store kinetic energy while the nuclear reactor is operating and then release the stored kinetic energy to cause the primary coolant to continue to flow through the nuclear reactor core to remove decay heat. The inertial energy coast down system may include an impeller and a flywheel having a mass. During normal reactor operation, the flowing primary coolant spins up the impeller and flywheel, and upon a shutdown event where the primary coolant pump stops pumping, the flywheel and impeller can cause the primary coolant to continue to flow during a coast down of the flywheel and impeller.

A method and apparatus of limiting power of a boiling water nuclear reactor system includes a reactor pressure vessel, a reactor core disposed in the reactor pressure vessel, a core shroud surrounding the reactor core, a downcomer region disposed between an inner surface of the reactor pressure vessel and the core shroud, a steam line connected to an upper end of the reactor pressure vessel and a condenser system that receives steam from the reactor pressure vessel. A portion of the condenser system condensate is returned to the reactor pressure vessel of the boiling water reactor inside the core barrel above the core rather than into the downcomer. Returning the condensate in this way increases the effectiveness of an isolation condenser system or if the condensate is a portion of the feedwater from the main condenser it provides an effective means to regulate core flow and core power.