Abstract: Systems and methods for injecting a carbonate-based sacrificial material into a nuclear reactor containment for containment of molten corium in severe nuclear reactor accidents are disclosed. Molten corium can be quickly cooled and solidified by the endothermic decomposition of the sacrificial material.

Abstract: System for confining and cooling melt from the core of a water-moderated nuclear reactor comprising a melt trap. The melt trap is installed in the reactor vessel bottom and provided with a cooled containment, consisting of outer and inner housings between which there is a sealant, and the filler for the melt dilution placed in the melt trap inner body. The melt trap inner body has a damper consisting of a central mantle, bearing ribs connected with the central mantle, titled plates, placed between the bearing ribs, the stops providing fastening of the damper to the melt trap body.

Abstract: This invention involves systems which provide for the safety of nuclear power plants that can be used in the event of serious accidents leading to the destruction of the housing and sealed containment structure of a reactor. In one aspect, the system can increase nuclear power plant safety by preventing the escape of liquid and solid radioactive materials (corium) from a melt confinement device in the event of a serious accident involving the escape of core melt from a nuclear reactor. The invention addresses the problem of increasing the efficiency and reliability of a melt confinement device by improving the conditions for cooling corium. The problem is solved by the use of a filler formed in upper cassettes and in a lower cassette. Said cassettes are configured with vertical and horizontal channels which provide for the uniform distribution of melt in the housing undergoing cooling.

Abstract: A device for confining nuclear reactor core melt comprising a melt trap and provided with a multilayer vessel containment, a filler, an upper support, and a bottom support comprising a horizontal embedded plate mounted in the concrete of a reactor pit. The plate comprises radial supports, the melt trap comprising radial supports, based on the radial support of the plate. The plate radial supports and the melt trap radial supports are connected with fasteners having holes in the form of hyperbolic surfaces. The radial supports and the clamps have oval holes. The upper support comprises turnbuckles, mounted in pairs on the upper part of the melt trap body so that the longitudinal axis of each radial support of the melt trap bottom support passes in projection at an equispaced distance from the fitting location of the paired turnbuckles and connecting the melt trap body with the reactor pit vertical wall.

Abstract: Systems and methods for injecting a carbonate-based sacrificial material into a nuclear reactor containment for containment of molten corium in severe nuclear reactor accidents are disclosed. Molten corium can be quickly cooled and solidified by the endothermic decomposition of the sacrificial material.

Abstract: An in-vessel cooling and power generation system according to the present disclosure may include a small scale reactor vessel, a heat exchange section provided inside the reactor vessel, and formed to supply supercritical fluid to receive heat from a reactor coolant system in the reactor vessel, an electric power production section comprising a supercritical turbine formed to produce electric energy using the energy of the supercritical fluid whose temperature has increased while receiving heat from the reactor coolant system, a cooling section configured to exchange heat with the supercritical fluid discharged after driving the supercritical turbine to shrink a volume of the supercritical fluid, wherein the supercritical fluid that has received heat from the reactor coolant system in the heat exchange section is formed to circulate through the electric power production section, and the cooling section.

Abstract: According to an embodiment, a core catcher has: a main body including: a distributor arranged on a part of a base mat in the lower dry well, a basin arranged on the distributor, cooling channels arranged on a lower surface of the basin connected to the distributor and extending in radial directions, and a riser connected to the cooling channels and extending upward; a lid connected to an upper end of the riser and covering the main body; a cooling water injection pipe open, at one end, to the suppression pool, connected at another end to the distributor; and chimney pipes connected, at one end, to the riser, another end being located above the upper end of the riser and submerged and open in the pool water.

Abstract: There is provided a cooling apparatus for a molten core material, including: two or more cooling material containers disposed under a reactor vessel including a nuclear reactor core and including a cooling material therein; a first screen disposed under the two or more cooling material containers and including two or more first through-holes; and a second screen disposed under the first screen and including two or more second through-holes, wherein an average size of the two or more first through-holes is greater than an average size of the two or more second through-holes.

Abstract: The present invention provides a porous cooling block for cooling corium, comprising: a base part that includes a plurality of pores; a plurality of porous cooling blocks that include a channel part that communicates with some of the plurality of pores of the base part; a sacrificial part that covers the exposed upper surfaces of the porous cooling blocks; and a cooling-water supply unit that supplies cooling water to the porous cooling blocks. Corium is cooled by using steam or cooling water discharged from the porous cooling blocks. Therefore, the corium can be cooled and solidified in the shape of a porous form. Further, the cooling water is uniformly supplied to one surface formed by the cooling block on the whole, thereby easily cooling the corium.

Abstract: According to an embodiment, a core catcher has: a main body including: a distributor arranged on a part of a base mat in the lower dry well, a basin arranged on the distributor, cooling channels arranged on a lower surface of the basin connected to the distributor and extending in radial directions, and a riser connected to the cooling channels and extending upward; a lid connected to an upper end of the riser and covering the main body; a cooling water injection pipe open, at one end, to the suppression pool, connected at another end to the distributor; and chimney pipes connected, at one end, to the riser, another end being located above the upper end of the riser and submerged and open in the pool water.

Abstract: The present invention relates to passive cooling systems and methods for cooling a spent fuel pool in a nuclear power plant in the absence of onsite and offsite power, e.g., in a station blackout event. The systems include a gap formed along the periphery of the spent fuel pool, a heat sink, one or more thermal conductive members, a water supply system for delivering water to at least partially fill the gap and conduct heat generated from the spent fuel pool through the gap to at least one thermal conductive member for transporting heat to the heat sink, and a thermal switch mechanism for activating and deactivating the water supply system. In particular, the passive spent fuel pool cooling systems and methods of the invention are useful when the active spent fuel pool cooling system is unavailable or inoperable.

Abstract: A nuclear reactor includes a pressure vessel and a nuclear reactor core comprising fissile material disposed inside the pressure vessel at the bottom of the pressure vessel. A secondary core containment structure includes a containment basket comprising insulation with a maximum stable temperature of at least 2200K cladded by steel. The bottom of the pressure vessel and the nuclear reactor core are disposed inside the containment basket with the containment basket spaced apart from the bottom of the pressure vessel by a clearance gap. The containment basket may comprise zirconia insulation cladded by steel. In some embodiments the clearance gap between the containment basket and the bottom of the pressure vessel is no larger than one meter. The secondary core containment structure may further comprise conduits arranged to inject water into the clearance gap between the containment basket and the bottom of the pressure vessel.

Abstract: A nuclear reactor includes a reactor core disposed in a reactor pressure vessel. A radiological containment contains the nuclear reactor and includes a concrete floor located underneath the nuclear reactor. An ex vessel corium retention system includes flow channels embedded in the concrete floor located underneath the nuclear reactor, an inlet in fluid communication with first ends of the flow channels, and an outlet in fluid communication with second ends of the flow channels. In some embodiments the inlet is in fluid communication with the interior of the radiological containment at a first elevation and the outlet is in fluid communication with the interior of the radiological containment at a second elevation higher than the first elevation. The radiological containment may include a reactor cavity containing a lower portion of the pressure vessel, wherein the concrete floor located underneath the nuclear reactor is the reactor cavity floor.

Abstract: A nuclear reactor including a lateral seismic restraint with a vertically oriented pin attached to the lower vessel head and a mating pin socket attached to the floor. Thermally insulating materials are disposed alongside the exterior surface of a lower portion of the reactor pressure vessel including at least the lower vessel head.

Abstract: There is provided a holding device which can hold a molten corium for a predetermined period even when the molten corium is exposed to heat or undergoes any chemical reaction and which is applicable to practical use. There is provided a holding device provided below a nuclear reactor pressure vessel for holding a molten corium, wherein the holding device includes a base material in contact with a cooling medium, and a multilayer stack structure on the base material. The multilayer stack structure has a first layer having heat-resistant property, a second layer formed on the first layer and having heat-resistant property with lower heat conductivity than that of the first layer, and a third layer formed on the second layer and having corrosion-resistant property and impact-absorbing property.

Abstract: An apparatus for retention of molten material for a Generation IV reactor after a nuclear power plant accident comprises an inner wall which is peripherally closed, a vapor channel wall with an opening at the bottom fixed in the inner side of the inner wall, a pressure vessel disposed in the vapor channel wall, a vapor rising channel formed between the pressure vessel and the vapor channel wall, and it further comprises an outer wall surrounding the inner wall, a core molten material retention apparatus fixed at the bottom of the inner wall, and a deflector keeping away from the inner wall and the core molten material retention apparatus to form a gap; wherein a coolant falling channel is formed between the outer wall and the deflector, a coolant inlet is disposed at the bottom of the deflector, and a coolant channel is disposed between the inner wall and the core molten material retention apparatus; a core molten material retention recess is disposed at the upper surface of the core molten material retention

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: When a power source is lost after an operation stop of a nuclear power plant, a first open/close valve is opened via a first battery at an early stage and steam in a reactor pressure vessel (RPV) is condensed in a suppression pool. The heat of the water in the suppression pool is transmitted to a cooling water pool located below inner space between first and second reactor containment vessels surrounding the RPV. A second open/close valve is opened via a second battery at the early stage and cooling water in a tank is injected into the RPV. After the early stage, a third open/close valve is opened via a third battery, and a cooling medium becomes steam by an evaporator in the RPV, the steam being condensed by a condenser disposed in the inner space to become a liquid of the cooling medium and is returned to the evaporator.

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: There is provided a holding device which can hold a molten corium for a predetermined period even when the molten corium is exposed to heat or undergoes any chemical reaction and which is applicable to practical use. There is provided a holding device provided below a nuclear reactor pressure vessel for holding a molten corium, wherein the holding device includes a base material in contact with a cooling medium, and a multilayer stack structure on the base material. The multilayer stack structure has a first layer having heat-resistant property, a second layer formed on the first layer and having heat-resistant property with lower heat conductivity than that of the first layer, and a third layer formed on the second layer and having corrosion-resistant property and impact-absorbing property.

Abstract: Core debris generated during a molten reactor core in a reactor containment vessel penetrating the reactor containment vessel is configured to be caught by a core catcher located beneath the reactor containment vessel which has a main body having first stage cooling water channels and second stage surrounded by cooling fins extending radially. The number of the second stage cooling channels is larger than that of the first stage cooling channels. Cooling water is supplied from a cooling water injection opening and distributed to the first cooling water channels at a distributor. An intermediate header is formed between the first and the second cooling water channels, and the cooling water is distributed to the second cooling water channels uniformly.

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 core catcher includes a holding surface that catches and holds corium and that introduces a coolant with which surroundings of the core catcher are filled into the core catcher and cool a whole of the core catcher by heat exchange with the introduced coolant. The holding surface and the cooling unit are constructed by arranging blocks which each include a polyhedron having at least one pair of parallel surfaces and having opening portion formed in a surface located in a lateral direction when a first surface that is one of the parallel surfaces is arranged as a bottom surface and are configured such that the polyhedrons communicate with each other via the opening portion when the polyhedrons are arranged adjacent in the lateral direction. The core catcher, as described above, can be achieved easier installation of the blocks without an increase in installation cost.

Abstract: An object is to provide a corium cooling structure that is capable of accumulating corium and debris that have flowed out from a reactor in small divided portions and of sufficiently cooling the high-temperature corium and debris, a reactor containment vessel provided with the same, and a nuclear power plant provided with the same. A capture portion that captures the corium that has flowed out from a reactor and a plurality of pipe portions that are provided in a coolant storing portion and into which the corium flows via the capture portion are provided.

Abstract: According to an embodiment, a nuclear reactor containment vessel has: a primary reactor containment vessel which contains a nuclear pressure vessel; a secondary reactor containment vessel and which is disposed outside the primary reactor containment vessel which has the pressure resistant properties and the leak-tightness which are equivalent to those of the primary reactor containment vessel; an air bag which is disposed within the secondary reactor containment vessel and which, when a failure occurs in primary reactor containment vessel, expands while receiving and encapsulating a high pressure gas discharged from the inside of the primary reactor containment vessel; and a gas phase vent pipe which connects the primary reactor containment vessel and the air bag.

Abstract: In a corium cooling promoting apparatus and a containment, a pressurized water reactor (12) is contained inside the containment (11), and a cavity (56) to which cooling water can be supplied in an emergency is provided below the pressurized water reactor (12). The cooling promoting apparatus (61) is disposed in the cavity (56), and an inclined plate (62) for spreading a corium (debris) from the pressurized water reactor (12) is provided, as the cooling promoting apparatus (61), at a position below the pressurized water reactor (12) in the cavity (56). The cooling of the corium falling from the nuclear reactor is thereby facilitated, and the corium is cooled at an early stage to improve safety.

Abstract: Nuclear reactor systems and methods are described having many unique features tailored to address the special conditions and needs of emerging markets. The fast neutron spectrum nuclear reactor system may include a reactor having a reactor tank. A reactor core may be located within the reactor tank. The reactor core may include a fuel column of metal or cermet fuel using liquid sodium as a heat transfer medium. A pump may circulate the liquid sodium through a heat exchanger. The system may include a balance of plant with no nuclear safety function. The reactor may be modular, and may produce approximately 100 MWe.

Abstract: An apparatus for passively cooling and retaining molten core material discharged from a damaged reactor vessel during a severe accident in the nuclear plant including: a molten core material retention tank to retain molten core material; a compressed gas tank storing high-pressure inert gas; a cooling water storage tank being installed higher than the molten core material retention tank; and a mixing means. The molten core material retention tank includes an outer retention vessel having at least one coolant hole, a porous protection vessel formed at an inside of the outer retention vessel, and a gravel layer formed between the outer retention vessel and the porous protection vessel. The apparatus can be installed in a reactor cavity without changing the compartment structure of a containment building, and makes it possible to prevent a steam explosion during the cooling process for the ultrahigh-temperature molten core material and to secure the reliability of the cooling process.

Abstract: A technical installation, especially a nuclear power plant, has a number of system components that are respectively supported by a number of beams, and a number of pressurized conduits. The technical installation is designed in such a way that secondary damage occurring in the surroundings of pressurized conduits are kept particularly low even if the pressurized conduits rupture. This is achieved in that at least one of the beams is embodied in a segmented manner in an area that is expected to be affected if a pressurized conduit ruptures, adjacent segments preferably being connected to each other via screw connections.

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: Heat from an ex-vessel mass of core material is removed to cooler regions of a containment envelope via liquid and/or vapor phase transport. Various aspects provide for contacting the ex-vessel core material with a material having properties including melting point, boiling point, and condensation kinetics such that condensation of the material in cooler regions of the containment envelope is at least as fast as evaporation of the material due to heat absorption from the core material and associated species.

Abstract: An assembly includes a base grid configured to be disposed below a pressure vessel and spaced vertically above a floor of a containment vessel to define a sump therebetween. The assembly further includes an annular wall extending vertically upwards from the floor and laterally bounding the base grid and the sump. The wall separates the sump from a suppression pool, an inlet passage extending through the wall and providing flow communication between the sump and the suppression pool, and an outlet passage extending through the wall and providing flow communication between the sump and the suppression pool.

Abstract: An apparatus for passively cooling and retaining molten core material discharged from a damaged reactor vessel during a severe accident in the nuclear plant including: a molten core material retention tank to retain molten core material; a compressed gas tank storing high-pressure inert gas; a cooling water storage tank being installed higher than the molten core material retention tank; and a mixing means. The molten core material retention tank includes an outer retention vessel having at least one coolant hole, a porous protection vessel formed at an inside of the outer retention vessel, and a gravel layer formed between the outer retention vessel and the porous protection vessel. The apparatus can be installed in a reactor cavity without changing the compartment structure of a containment building, and makes it possible to prevent a steam explosion during the cooling process for the ultrahigh-temperature molten core material and to secure the reliability of the cooling process.

Abstract: Core debris generated during a molten reactor core in a reactor containment vessel penetrating the reactor containment vessel is configured to be caught by a core catcher located beneath the reactor containment vessel which has a main body having first stage cooling water channels and second stage surrounded by cooling fins extending radially. The number of the second stage cooling channels is larger than that of the first stage cooling channels. Cooling water is supplied from a cooling water injection opening and distributed to the first cooling water channels at a distributor. An intermediate header is formed between the first and the second cooling water channels, and the cooling water is distributed to the second cooling water channels uniformly.

Abstract: The invention relates to a Tub-like retainer for a nuclear core melt, comprising an outer envelope with a multi-layer lining along its inner surface, wherein said lining comprises, from inside to outside, a monolithic sacrificial layer, a layer made of high temperature resistant shaped parts and a monolithic filling layer between said envelope and said layer made of shaped parts.

Abstract: A nuclear reactor housing includes a vertically held pressurized water reactor and a cavity formed below the pressurized water reactor. A granulating member is positioned between the pressurized water reactor and the cavity and that accelerates granulation of debris falling from the pressurized water reactor into the cavity.

Abstract: An apparatus is described for catching and cooling a melt, in particular a core melt in a containment of a nuclear power plant. A porous body with which the melt comes into contact is provided. A pre-pressurized coolant is fed to the porous body so that the cavities in the porous body are filled with the coolant. After contact between the melt and the porous body, the pre-pressurized coolant penetrates into the melt and as a result leads to fragmentation, solidification and long-term cooling.

Abstract: A nuclear power plant (18) and its heat exhanger (26) are enclosed in an envelope (22) which is suspended above a bored shaft (14) from a support stem (30). When appropriate, the stem (30) can be melted by a furnace (34) to drop the envelope (22) to the bottom of the shaft (14). Sand (42) can then be dropped onto the envelope (22) through a drainage pipe (46). While the nuclear power plant (18) is operating and suspended in the shaft, spent fuel rods (70) are dropped into a sand blasting machine's hopper (130), mixed with sand and dropped into a bag (134) containing a small explosive device. The bag (134) is then dropped to the bottom of the shaft (14) and the explosive detonated to scatter the contents of the bag (134). Optionally, more sand or earth is then added to reduce heat and radiation to acceptable levels.

Abstract: An apparatus is described for catching and cooling a melt, in particular a core melt in a containment of a nuclear power plant. A porous body with which the melt comes into contact is provided. A pre-pressurized coolant is fed to the porous body so that the cavities in the porous body are filled with the coolant. After contact between the melt and the porous body, the pre-pressurized coolant penetrates into the melt and as a result leads to fragmentation, solidification and long-term cooling.

Abstract: A heat removal system for the under reactor pressure vessel area of a boiling water nuclear reactor system that provides both protection of the containment boundary from attack by molten core debris and cools the molten core debris to prevent a breach of the containment boundary in the unlikely event of a severe accident where the molten core penetrates the lower head of the reactor vessel is described. The heat removal system includes a glass matrix slab positioned adjacent the floor of the containment and a plurality of heat tubes at least partially embedded in the glass matrix slab and extending into the area under the nuclear reactor pressure vessel. The cooling system also includes a passive containment cooling system, and fused vent pipes connecting the suppression pool with the drywell.

Abstract: The container collects and spreads core melt in a nuclear power plant. The container has a structured bottom, particularly a cartridge-like bottom. The bottom has a material of good thermal conductivity, a plurality of geodetically highest points and a plurality of geodetically lowest points (5) and an outer wall. The outer wall extends with an upward slope between a geodetically lowest point and an adjacent geodetically highest point. A steam conduit which runs through the container interior is provided at each geodetically highest point. The container allows external cooling of core melt. As a result, the formation of radioactive aerosols, the occurrence of a steam explosion and the formation of hydrogen are avoided. In addition, the cooling is made particularly effective by the upward slope of the outer wall since the formation of a spatially fixed steam region, which is associated with a decrease in thermal conductivity, is prevented.

Abstract: The present invention relates to a safety design and risk management of a reactor of a nuclear plant, and more particularly, to an ex-vessel core melt device preventing molten core concrete interaction, which is to handle very severe accidents caused by cooling-function loss to nuclear fuel. Due to the large quantity of nuclear fuel existing in the reactor and decay heat which is latent and continuously generated within the fuel mass for a long time after the nuclear chain reaction, the nuclear fuel is melted in gross at temperature up to 2,500 degrees centigrade, and thereby the surrounding structures and a reactor vessel are attacked and damaged, and in the end, a containment building floor is eroded. This situation may cause environmental radioactivity either by ultimate penetration of the cavity floor or by the buildup of non-condensable gas pressure (i.e., pressurizing the containment building structure), unless the reaction is arrested.

Abstract: A nuclear reactor plant with a light water reactor comprises a containment (1) having an upper space (2) and a lower space (3). The lower space is separated from the upper space by a separating member (4) and arranged to house a cooling medium (16). Furthermore, the plant comprises a reactor vessel (9) housing a reactor core (10) and provided in the upper space (2). The separating member (4) comprises a portion (7) which is arranged to be located at such a position that the surface portion (7) facing the lower space (3) is in contact with the cooling medium (16). The reactor vessel is provided above the portion (7).

Abstract: A gap forming structure for use with water cooled nuclear reactors is invented to prevent overheating and ultimately structurally failing of the lower head of a reactor vessel in a nuclear reactor core meltdown accident by virtue of a cooling effect in the gap structure for facilitating the retention of accumulated molten core debris. Single layer or multilayer gap structures can be installed either inside or outside the vessel lower head by joining, or fastening structures or secured to the instruments/control guide tubes within the vessel. The water cooling capacity inside the gap can prevent the vessel lower head from overheating and subsequently failing and thus defend against severe accidents by preventing the lower head of the reactor vessel from rupturing.

Abstract: A retaining device has a multi-layer protective cladding for protecting the bearing and containment structure of a spreading chamber for the controlled spread and cooling of a melt from a nuclear reactor pressure vessel. The spreading chamber is configured under the spreading concept, i.e. the melt spreads and cools therein. The protective cladding has at least two layers: an outer sacrificial layer acts as a thermal shock barrier and melting substance; a protective and insulating layer, disposed inside the sacrificial layer and protecting the underlying bearing and containment structure, acts as thermal protection layer and retaining layer for the hot melt. The protective and insulating layer includes a first partial layer of fireproof concrete adjacent the bearing and containment structure, and a second partial layer of temperature-resistant ceramic blocks, in particular ZrO2 adjacent the sacrificial layer.

Abstract: A nuclear reactor includes a core melt collection chamber having walls with multilevel protective layers. The layers include one layer part made of refractory concrete and another layer part made of ceramic bricks. The protective layers are anchored to the structural concrete of the collection chamber. In order to provide structural simplification, the layer part made of refractory concrete is constructed in the form of prefabricated blocks which are jointed together and are fastened to the structural concrete, and the layer part made of ceramic bricks is braced to the blocks of the layer part made of refractory concrete.

Abstract: A nuclear reactor includes a propagation space for core melt. The propagation space has a coolant conduit leading to a coolant reservoir and a device which opens in a temperature-dependent manner. The coolant conduit in the propagation space is a spray conduit having a spraying area which covers the cross-section of the propagation space over a large area. The device is controlled in such a way that it opens when the core melt enters the propagation space. Spraying gives rise to a crust on the core melt which reduces heat radiation. At the same time, the propagation space fills with a steam atmosphere which drastically reduces the thermal load on building structures.

Abstract: A device for collecting core melt from a reactor pressure vessel improves a flow of the core melt out of the reactor pressure vessel. A prechamber is disposed below the reactor pressure vessel and a spreading chamber for the core melt is disposed laterally next to the reactor pressure vessel. The spreading chamber is connected to the prechamber through a channel. A base unit forms a bottom region at least of the prechamber and is made of a material having high thermal conductivity.

Abstract: A nuclear power plant has a reactor core and a containment chamber for receiving core melt of the reactor core. A cooling system for cooling the containment chamber includes a flooding container to be filled with coolant fluid. A cooling pipe leads from the flooding container to the containment chamber. A passively opening closure element closes the cooling pipe in the flooding container and opens as a function of a level of the coolant fluid.

Abstract: A device for collecting and cooling reactor-meltdown products from a reactor pressure vessel includes an antechamber disposed below the reactor pressure vessel and an expansion chamber for the reactor-meltdown products. A channel which is disposed between the antechamber and the expansion chamber has a partition being destructible by the reactor-meltdown products. A closure element which connects a coolant reservoir to the expansion chamber is destructible by the reactor-meltdown products. A method for collecting and cooling reactor-meltdown products from a reactor pressure vessel includes collecting reactor-meltdown products in an antechamber disposed below the reactor pressure vessel and keeping them in the antechamber for a predetermined time interval. A partition disposed between the antechamber and an expansion chamber is destroyed with the reactor-meltdown products. The reactor-meltdown products penetrate from the antechamber into the expansion chamber and are spread in the expansion chamber.