A catalytic recombiner and filter apparatus is especially suited for placement in a containment of a nuclear reactor. The apparatus has a natural convection flow duct with a number of catalytic elements for recombining hydrogen and oxygen contained in a gas flow through the flow duct. The catalytic recombiner and filter apparatus provides for reliable hydrogen reduction and iodine filtering for a gas flow even for a comparatively long period of operation. The catalytic recombiner and filter apparatus includes a number of adsorber elements with iodine adsorbing surfaces and with macroscopic flow channels in between. The iodine adsorbing surfaces are flown over by the gas flow, and the adsorber elements are arranged, when in use, downstream of the catalytic elements in a direction of the gas flow.

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.

An operating floor confinement has an operating floor, a sidewall that surrounds the operating floor, a ceiling that is provided on an upper portion of the sidewall, a reactor well, a fuel pool, a dryer and separator pit, an equipment hatch that is provided on the sidewall, an air lock that is provided on the sidewall, and an isolation valve that is provided in a penetration line. The operating floor confinement forms a pressure boundary having pressure resistance and a leakage protection function. The operating floor confinement is separated from an equipment area of the reactor building and has no blowout panel.

A nuclear power system includes a reactor vessel that includes a reactor core mounted within a volume of the reactor vessel, the reactor core including one or more nuclear fuel assemblies configured to generate a nuclear fission reaction; a containment vessel sized to enclose the reactor vessel such that an open volume is defined between the containment vessel and the reactor vessel; and a boron injection system positioned in the open volume of the containment vessel and including an amount of boron sufficient to stop the nuclear fission reaction or maintain the nuclear fission reaction at a sub-critical state.

A nuclear power system includes a reactor vessel that includes a reactor core that includes nuclear fuel assemblies configured to generate a nuclear fission reaction; a riser positioned above the reactor core; a primary coolant flow path that extends from a bottom portion of the volume through the reactor core and through an annulus between the riser and the reactor vessel; a primary coolant that circulates through the primary coolant flow path to receive heat from the nuclear fission reaction and release the heat to generate electric power in a power generation system; and a control rod assembly system positioned in the reactor vessel and configured to position control rods in only two discrete positions.

A nuclear power system includes a reactor vessel that includes a reactor core mounted, the reactor core including nuclear fuel assemblies configured to generate a nuclear fission reaction; a riser positioned above the reactor core; a primary coolant flow path that extends from a bottom portion of the volume below the reactor core, through the reactor core, within the riser, and through an annulus between the riser and the reactor vessel back to the bottom portion of the volume; a primary coolant that circulates through the primary coolant flow path to receive heat from the nuclear fission reaction and release the received heat to generate electric power in a power generation system fluidly or thermally coupled to the primary coolant flow path; and a control system communicably coupled to the power generation system and configured to control a power output of the nuclear fission reaction independent of any control rod assemblies during the normal operation.

A filtered containment venting system includes a filtered containment venting tank having: an organic iodine remover for collecting organic iodine; scrubbing water for collecting inorganic iodine; and an alkalizing agent for adding an action of buffering a pH value to the scrubbing water.

In view of above problems, an object of the invention is to provide a primary containment vessel venting system having a structure capable of continuously discharging vapor in a primary containment vessel out of the system and continuously reducing pressure of the primary containment vessel without discharging radioactive noble gases to the outside of the containment vessel and without using an enclosing vessel or a power source. In order to achieve the above object, an nuclear power plant of the invention includes a primary containment vessel which includes a reactor pressure vessel, a radioactive substance separation apparatus which is disposed inside the primary containment vessel and through which the radioactive noble gases do not permeate but vapor permeates, a vent pipe which is connected to the radioactive substance separation apparatus, and an exhaust tower which is connected to the vent pipe and discharges a gas, from which a radioactive substance is removed, to the outside.

A catalytic recombiner and filter apparatus is especially suited for placement in a containment of a nuclear reactor. The apparatus has a natural convection flow duct with a number of catalytic elements for recombining hydrogen and oxygen contained in a gas flow through the flow duct. The catalytic recombiner and filter apparatus provides for reliable hydrogen reduction and iodine filtering for a gas flow even for a comparatively long period of operation. The catalytic recombiner and filter apparatus includes a number of adsorber elements with iodine adsorbing surfaces and with macroscopic flow channels in between. The iodine adsorbing surfaces are flown over by the gas flow, and the adsorber elements are arranged, when in use, downstream of the catalytic elements in a direction of the gas flow.

The invention is related to safety systems for nuclear power plants (NPP) which can be used in various operational modes, including emergency mode, and is aimed at controlling air flows inside NPP containment buildings.

NPP containment building separation system dividing the NPP containment building into isolated rooms. It includes the containment building separation shutters located in the circular gap which divides the containment building rooms and the containment building walls; an air supply unit connected to a manifold ring which, in turn, is connected to the air-inflated shutters designed to ensure insulation of the airspace inside the containment building rooms when inflated and at connecting the airspace when deflated. In emergency mode the air supply to the air-inflated shutters is terminated, the shutters get deflated and fully open the circular gap which ensures convection process throughout the whole area of containment building.