Abstract: According to an embodiment, a nuclear reactor containment vessel is provided with a device for holding a molten material of the reactor core and with spacers. The device is installed on the pedestal floor. A holding container which is open upward and a water supply container which is provided below the holding container are provided inside the outer peripheral surface. A water supply flow path extends to the water supply container from the gap between the inner surface of the pedestal side wall and the outer peripheral surface of the device for holding a molten material of the reactor core. The spacers are engaged with the upper end of an outer riser extend between the outside of the outer riser and the inner surface of the pedestal side wall, and prevent the eccentricity of the device.

Abstract: An embodiment of a nuclear power plant has: a reactor vessel containing a core; a reactor containment vessel containing the reactor vessel; and a radiation heat reflecting member disposed at a portion below the reactor vessel inside the reactor containment vessel. The radiation heat reflecting member may block radiation heat, which is emitted toward a side wall surface of the reactor containment vessel from the core that has been put in a molten state by an accident and flowed downward from the reactor vessel to be accumulated at a lower portion of the reactor containment vessel. The radiation heat reflecting member may block radiation heat, which is emitted toward a supporting structure supporting devices disposed inside the reactor containment vessel.

Abstract: A pressure suppression and decontamination apparatus for a reactor container which is provided with a reactor pressure vessel containing nuclear core fuel and forms a dry well space including, a dry well cooling unit for cooling a gas in the dry well space and for producing a condensate of the gas, a circulation device for leading the gas in the dry well space to the dry well cooling unit, and a sprinkling device for sprinkling the condensate in the dry well space.

Abstract: A water leak detection floor transversally suspended by a pedestal side wall is installed between a reactor pressure vessel and a molten core holding apparatus. If a water leak occurs at the reactor pressure vessel, the water leak detection floor receives and detects the leak water. In a core meltdown accident, corium melts and penetrates the water leak detection floor and deposits on the molten core holding apparatus.

Abstract: A nuclear reactor containment vessel cooling equipment has: a dry well cooler casing in a containment vessel, having an opening at its top and a shutter at its lower part; a heat transfer tube arranged at an upper part in the dry well cooler casing; a forced cooling water circulation system for feeding cooling water from outside of the containment vessel into the heat transfer tube by a pump; a blower for mobilizing gas around the heat transfer tube; an external pool container arranged outside the containment vessel and above the heat transfer tube and containing cooling water; and a gravity-driven cooling system to supply cooling water in the external pool container into the heat transfer tube, utilizing gravity.

Abstract: A pressure suppression and decontamination apparatus for a reactor container which is provided with a reactor pressure vessel containing nuclear core fuel and forms a dry well space including, a dry well cooling unit for cooling a gas in the dry well space and for producing a condensate of the gas, a circulation device for leading the gas in the dry well space to the dry well cooling unit, and a sprinkling device for sprinkling the condensate in the dry well space.