Abstract: A containment vessel for containing a reactor pressure vessel, a reactor core, and a steam generator of a pressurized water reactor includes a main body equipped with a polar crane, a diaphragm set above the polar crane that partitions the main body, before and after a loss-of-coolant accident (LOCA), into an upper vessel including a dome part having an open space and a lower vessel isolated from the upper vessel, a pressure suppression chamber including a suppression pool that stores water and a gas phase in communication with the open space, a LOCA vent pipe connecting the suppression pool to the lower vessel, and a vacuum breaker that equalizes pressure by allowing gas flow from the upper to the lower vessel when a pressure difference between the upper and lower vessels exceeds a preset value. The lower vessel contains all equipment and piping constituting a reactor pressure boundary.

Abstract: According to an embodiment, a pressurized water reactor plant has a primary system which includes: a reactor vessel for housing a reactor core which is cooled by a primary coolant, a single steam generator, a hot leg pipe for connecting the reactor vessel and the steam generator, cold leg pipes, at least two primary coolant pumps, and a pressurizer for pressurizing the primary coolant pressure boundary in which the primary coolant flows. The plant also has: a passive cooling and depressurization system which is a primary depressurization means for equalizing the primary system pressure to the secondary system pressure at the time of a tube rupture accident of the steam generator, and a reactor containment vessel containing the primary system and cooling the primary system by air cooling. Thus, a compact pressurized water rector with high economic efficiency, safety, and reliability can be provided.

Abstract: According to an embodiment, a molten-core retention structure comprises the following inside a reactor vessel that contains a reactor core: a bottom support plate, in which vertically penetrating flow holes are formed, that is provided beneath the core and supports the core; a bottom support plate support that is affixed to the reactor vessel and supports the bottom support plate; a thermally insulating spacer; a reticulated heat path that is affixed to the bottom support plate support with the thermally insulating spacer interposed therebetween and contacts the bottom support plate; and vertical heat paths that extend downwards from the reticulated heat path. The reticulated heat path and the vertical heat paths have higher coefficients of thermal conductivity than the thermally insulating spacer.

Abstract: A passive cooling and depressurization system for a pressurized water nuclear plant is provided with a cooling water pool, a steam supply piping, a heat exchanger, a steam supply valve, a coolant return pipe and an outlet valve. The steam supply piping extends from the gas phase of the pressurizer. The heat exchanger exchanges heat between water stored in the cooling water pool and steam flowing through the steam supply piping. The steam supply valve is equipped on the steam supply piping. The coolant return pipe extends from the heat exchanger to a liquid phase of the reactor pressure boundary. The outlet valve is equipped on the coolant return pipe.

Abstract: A passive cooling and depressurization system for a pressurized water nuclear plant is provided with a cooling water pool, a steam supply piping, a heat exchanger, a steam supply valve, a coolant return pipe and an outlet valve. The steam supply piping extends from the gas phase of the pressurizer. The heat exchanger exchanges heat between water stored in the cooling water pool and steam flowing through the steam supply piping. The steam supply valve is equipped on the steam supply piping. The coolant return pipe extends from the heat exchanger to a liquid phase of the reactor pressure boundary. The outlet valve is equipped on the coolant return pipe.

Abstract: According to an embodiment, a pressurized water reactor plant has a primary system which includes: a reactor vessel for housing a reactor core which is cooled by a primary coolant, a single steam generator, a hot leg pipe for connecting the reactor vessel and the steam generator, cold leg pipes, at least two primary coolant pumps, and a pressurizer for pressurizing the primary coolant pressure boundary in which the primary coolant flows. The plant also has: a passive cooling and depressurization system which is a primary depressurization means for equalizing the primary system pressure to the secondary system pressure at the time of a tube rupture accident of the steam generator, and a reactor containment vessel containing the primary system and cooling the primary system by air cooling. Thus, a compact pressurized water rector with high economic efficiency, safety, and reliability can be provided.

Abstract: A containment vessel for containing a reactor pressure vessel and steam generators has a main containment vessel, a diaphragm, a pressure suppression chamber, LOCA vent pipes. The reactor pressure vessel contains a reactor core of a pressurized water reactor. The diaphragm partitions the main containment vessel into an upper vessel and a lower vessel. The pressure suppression chamber has a suppression pool to store water and gas phase of the pressure suppression chamber communicates with the upper vessel. The LOCA vent pipes connect the pressure suppression chamber to the lower vessel. All of the equipments and piping that constitute the reactor pressure boundary, including the reactor pressure vessel, the steam generators, a cold leg pipe and a hot leg pipe, are contained in the lower vessel.