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 breaker valve assembly for a nuclear reactor containment includes a valve body, a valve body insert, and a lid. The valve body includes a first side wall defining a chamber, a first opening in a top portion of the first side wall, and a second opening in a bottom portion of the first side wall. The second opening communicates with the first opening of the valve body. The valve insert body includes a second side wall defining a second chamber, and a third opening in a bottom portion of the second side wall. The valve insert body is nested in the valve body. The lid is arranged on an upper edge of the side wall of the valve insert body. The valve insert body is configured to move substantially vertically with respect to the valve body.

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.

An organic iodine trapping apparatus and method efficiently traps organic iodine in a nuclear reactor container vessel. A liquid vessel contains a non-volatile liquid (e.g., ionic liquid or interfacial active agent solution) capable of decomposing organic iodine. An introduction pipe introduces a fluid containing organic iodine in the nuclear reactor container vessel to the non-volatile liquid. The non-volatile liquid is heated by heat in the nuclear reactor container vessel or reaction heat of the fluid in the nuclear reactor container vessel. Then, the trapping apparatus decomposes and traps the organic iodine. The organic iodine trapping method includes heating a non-volatile liquid capable of decomposing organic iodine by heat in the nuclear reactor container vessel or reaction heat of fluid in the nuclear reactor container vessel; making the fluid containing organic iodine pass through the heated non-volatile liquid; and decomposing and trapping the organic iodine in the non-volatile liquid.

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.

As an organic iodine remover that removes organic iodine in a containment vessel of a nuclear reactor, an organic agent (for example, an ionic liquid, an interfacial active agent, a quaternary salt, or a phase transfer catalyst) having a function of dissolving and decomposing the organic iodine and retaining iodine is used. The organic iodine remover is a substance composed of a cation and an anion. The organic iodine remover is, in particular, an organic iodine remover in which, in a structure of the cation of the organic agent, carbon or oxygen is bonded to, via a single bond, to a phosphorus element, a sulfur element or a nitrogen element, the number of carbon chains is 2 or more, and an anionic structure is configured with a substance with high nucleophilicity. By using such an organic agent, the organic iodine is removed with an efficiency of 99% or more.

To provide an iodine trapping apparatus capable of trapping organic iodine in a wide temperature range with high efficiency. The iodine trapping apparatus includes a first trapping agent 2 capable of trapping organic iodine in a gas in a nuclear power structure main body. The first trapping agent 2 contains a generating and trapping component which generates an iodide ion (I.sup.−) from organic iodine (RI) and traps the generated iodide ion, and a generating component which is different from the generating and trapping component, generates an iodide ion from the organic iodine at least at 100° C. to 130° C., and traps the generated iodide ion in the generating and trapping component.

A flow restrictor nozzle for a pressurized vessel of a nuclear reactor may comprise a nozzle body including an inlet face and an outlet face. The nozzle body may define a plurality of internal flow paths extending from the inlet face to the outlet face. Each of the plurality of internal flow paths may include a convergent section, a throat section, and a divergent section.

A nuclear reactor containment atmospheric filter system includes dedicated piping, valves, a control system, and a chemical injection system. An outlet of the piping can release atmospheric effluent from a reactor containment vessel into a lower portion of a spent fuel pool. The chemical injection system can release a chemical into the spent fuel pool to facilitate a reaction with the released atmospheric effluent. The reaction can assist in neutering deleterious environmental impact of the atmospheric effluent. The filter system can filter and cool contaminated air and steam vapor released from the reactor containment vessel, and prevent vessel overpressure and radioactive release.

A radioactive noble gas removal filter, a filter unit, and a nuclear reactor containment vessel vent system with improved durability are provided. The radioactive noble gas removal filter according to the present invention includes a polyimide film including a structural unit represented by general formula (1).

##STR00001##