Classifications

• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23L—FOODS, FOODSTUFFS, OR NON-ALCOHOLIC BEVERAGES, NOT COVERED BY SUBCLASSES A21D OR A23B-A23J; THEIR PREPARATION OR TREATMENT, e.g. COOKING, MODIFICATION OF NUTRITIVE QUALITIES, PHYSICAL TREATMENT; PRESERVATION OF FOODS OR FOODSTUFFS, IN GENERAL
  • A23L7/00—Cereal-derived products; Malt products; Preparation or treatment thereof
  • A23L7/10—Cereal-derived products
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C9/00—Emergency protection arrangements structurally associated with the reactor, e.g. safety valves provided with pressure equalisation devices
  • G21C9/016—Core catchers
• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23P—SHAPING OR WORKING OF FOODSTUFFS, NOT FULLY COVERED BY A SINGLE OTHER SUBCLASS
  • A23P30/00—Shaping or working of foodstuffs characterised by the process or apparatus
  • A23P30/20—Extruding
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E30/00—Energy generation of nuclear origin
  • Y02E30/30—Nuclear fission reactors

Definitions

• the present invention relates to an apparatus and a method for retaining and cooling molten core material in a reactor cavity, and more particularly, to an apparatus and a method for stably retaining and cooling molten core material inside a reactor cavity, by which when the molten core material releases out of a reactor vessel at a severe accident of meltdown in a nuclear power plant, the released molten core material does not erode the reactor cavity contaminating neighboring soil or threaten safety of a containment building.
• a nuclear power plant includes hundreds of systems having separate functions. These systems are roughly classified into a nuclear steam supply system (NSSS) having a nuclear reactor as its main element, a turbine/generator system having a generator driven by supplied steam and other auxiliary equipments.
• NSSS nuclear steam supply system
• the nuclear reactor controls large amount of energy instantaneously produced during a nuclear reaction to be slowly released so that nuclear energy can be utilized for real life.
• a method for cooling the molten core material by directly supplying the cooling water to the molten core material has high efficiency, but it is problematic in that the molten core material of high temperature directly reacts to the cooling water in a closed space to cause rapid steam generation thereby potentially creating steam explosion.
• a core catcher having elongated molten core catch parts was proposed in Japanese Patent Publication No. 1996-43575.
• the conventional apparatus has a plurality of molten core catcher parts 110 below a reactor vessel 100.
• molten core released from the reactor vessel 100 during a severe accident in a nuclear power plant is retained in the molten core catcher parts 110, and the retained molten core is cooled by cooling water 120 filled around the molten core catcher parts 110.
• the above-described apparatus cools the molten core of high temperature by bringing the molten core into indirect contact with the cooling water. Accordingly, heat transfer efficiency between the molten core and the cooling water is undesirably reduced and thus a very large cooling water tank is required.
• the apparatus for cooling the molten core material of the related art is designed to forcibly cool down the molten core material using an active device such as a pump.
• an active device such as a pump.
• this not only degrades the reliability when a severe accident occurs but also decreases cooling ability of the pump as time goes on so that decay heat coming from the molten core material cannot be effectively removed. Accordingly, it is particularly problematic in a long-term cooling.
• the object of the present invention is to provide an apparatus and a method for effectively removing decay heat as well as guaranteeing safety of neighboring buildings by preventing steam explosion during cooling process that uses interaction between molten core material and cooling water while effectively retaining the molten core material within a containment building.
• the present invention provides an apparatus for retaining and cooling molten core material releasing from a reactor vessel due to meltdown, the apparatus comprising: a plate-shaped glass-material mixing part formed in a lower portion of the reactor vessel and having a glass material layer on its upper surface, such that molten core material that has passed through the reactor vessel mixes with glass material to lower a heat generation density; and a plurality of cooling- water retention tanks stacked in form of multi-layers below the glass-material mixing part, with cooling water containing inert gases being filled inside the cooling-water retention tanks, for cooling down the molten core material of high temperature.
• an apparatus for retaining and cooling molten core material for performing a long-term cooling which includes: a cooling- water supply part provided in a lateral side of the glass-material mixing part and the cooling-water retention tanks, the cooling-water supply part including a cooling-water storage tank, and a passage and a valve formed at one side of the cooling- water storage tank, for removing decay heat by additionally supplying the cooling water to the molten core material cooled down by the cooling water in the cooling-water retention tanks.
• the glass-material mixing part includes: a support plate installed at a lower portion of the reactor vessel, inclined at a predetermined angle, and formed with material not molten even if it contacts the molten core material; a glass material layer formed with a predetermined thickness on an upper surface of the support plate; and a blocking wall installed at a lower end of the inclined support plate, and formed of material that melts when it contacts the molten core material, for preventing the glass material formed on an upper surface of the support plate from flowing down.
• the glass material layer may be made of glass or graphite.
• Each of the cooling- water retention tanks may have a body made of material that melts when it contacts the molten core material of high temperature.
• the cooling-water supply part may further include a filtering unit on an upper portion of a cooling- water storage tank so that water from the condensing steam generated by interaction between the cooling water and the molten core material can flow back to the cooling- water storage tank.
• a method for retaining and cooling down molten core material releasing from a reactor vessel due to meltdown including steps of: (1) retaining the molten core material in a cavity of a containment building to restrict a passage thereof and mixing the molten core material with glass material to lower a heat generation density; and (2) causing the molten core material mixed with the glass material to flow down to cooling-water retention tanks stacked at a lower portion and contacting the mixture with cooling water containing inert gases in the cooling- water retention tanks, thereby cooling the molten core material.
• the method may further include the step 3 of, after the step 2: opening a valve of a cooling-water supply part to supply cooling water through a passage from a cooling- water storage tank to remove decay heat from the molten core material, thereby achieving a long-term cooling.
• the method may further include the step of: allowing water from the condensing steam generated by interaction between the cooling water and the molten core material to flow back to the cooling-water storage tank, thereby recycling the cooling water.
• the molten core material may be mixed with glass material in a glass material layer formed on an upper surface of a support plate inclined at a predetermined angle below the reactor vessel.
• the molten core material mixed with the glass material may fall down to the cooling-water retention tanks, which have a predetermined slope with respect to a bottom of a containment building and are stacked in form of multi-layers at a lower portion, and the mixture may sequentially flow along the predetermined slope to melt the cooling-water retention tanks and contact the cooling water containing inert gases inside the cooling-water retention tanks.
• FIG. 1 is a schematic view of a non-contact type apparatus for cooling molten core material of a related art
• FIG. 2 is a schematic view of an apparatus for cooling molten core material according to the present invention
• FIG. 3 is a detailed view of a glass-material mixing part of the present invention.
• FIGs. 4A and 4B are cross-sectional views of stacked cooling-water retention tanks of the present invention.
• FIG. 5 is a transversal, cross-sectional view of the cooling- water retention tank illustrated in FIG. 4.
• FIG. 2 is a schematic view of an apparatus for cooling molten core material according to the present invention, which will be described as follows.
• a reactor vessel 10 is arranged in an upper portion of a containment building 1 of a predetermined size, and a glass- material mixing part 20 and cooling-water retention tanks 30 are provided in a lower cavity inside the containment building 1.
• the glass-material mixing part 20 is intended to mix the molten core material 5 releasing from the reactor vessel with glass material first in order to lower a heat generation density.
• the glass-material mixing part is shaped as a plate inclined at a predetermined angle ⁇ .
• the cooling-water retention tanks 30 are stacked in form of multi-layers below the glass-material mixing part 20.
• the molten core material 5 mixed with the glass material in the glass-material mixing part 20 falls down to the cooling- water retention tanks 30, where the mixture interacts with the cooling water containing inert gases inside the cooling-water retention tanks 30, whereby the mixture is cooled down.
• a body of the cooling-water retention tanks 30 may be made of material that can be molten by the molten core material of high temperature.
• the molten core material 5 is mixed with the glass material first so that the heat generation density is lowered and further a steam explosion due to interaction with the cooling water can be suppressed using the inert gases, thus heat transfer efficiency by a direct contact with the cooling water can be increased and risk of steam explosion can be remarkably reduced.
• the cooling-water retention tanks 30 stacked in multi-layers may be inclined at a predetermined angle ⁇ with respect to a bottom of the containment building 1 so that the molten core material 5 may sequentially flows down.
• the present invention can include a cooling-water supply part 40 having a cooling- water storage tank 43, a cooling- water passage 42 and a valve 41 formed on one side of the cooling-water storage tank 43 in order to remove decay heat after the cooling by the cooling water of the cooling-water retention tanks 30.
• a cooling-water supply part 40 having a cooling- water storage tank 43, a cooling- water passage 42 and a valve 41 formed on one side of the cooling-water storage tank 43 in order to remove decay heat after the cooling by the cooling water of the cooling-water retention tanks 30.
• the present invention further includes a filtering device 44 at an upper portion of the cooling- water supply part 40. Steam generated by interaction between the cooling water and the molten core material is condensed into water, and the water flows back to the cooling- water storage tank 43, whereby the cooling water is recycled. Therefore, a long-term cooling can be effectively performed.
• a water-supply line (not shown) for maintaining supplied water to an appropriate level all the time is connected to the cooling- water storage tank 43.
• FIG. 3 is a detailed view of a glass-material mixing part of the present invention.
• the present invention has the glass-material mixing part 20 below the reactor vessel, which serves to mix the molten core material 5 with the glass material first in order to lower a heat generation density.
• the glass-material mixing part 20 includes a support plate 21 preferably inclined at a predetermined angle ⁇ .
• the support plate 21 is made of material that does not melt even if it contacts the molten core material 5. Such configuration is intended for allowing the molten core material 5 to flow toward a lower portion of the containment building after the material 5 that has passed through the reactor vessel is mixed with the glass material.
• a glass material layer 22 formed in a predetermined thickness is provided to an upper surface of the support plate 21.
• the molten core material that has passed through the reactor vessel is mixed with the glass material in the glass material layer 22.
• the glass material layer 22 may be made of glass or graphite.
• the glass or the graphite may be prepared in form of grains or powder.
• the glass material is mixed with the molten core material 5 to lower the heat generation density.
• a blocking wall 23 is installed at a lower end of the inclined support plate 21.
• the blocking wall 23 may be made of material that melts when it contacts the molten core material 5 of high temperature releasing from the reactor vessel. Then, the blocking wall 23 prevents the glass material formed on the upper surface of the support plate 21 from flowing down in normal times and is molten by the molten core material 5 of high temperature when a severe accident occurs in the nuclear power plant so that the material 5 mixed with the glass material can flow down to the lower portion of the containment building.
• FIGs. 4 and 5 are views illustrating a cross-section of stacked cooling-water retention tanks and a transversal, cross-section of a cooling-water retention tank.
• the present invention has the cooling- water retention tanks 30 including the cooling water containing inert gases to cool down the molten core material 5.
• the cooling- water retention tanks 30 can be stacked in multi-layers below the glass-material mixing part 20.
• an arrangement direction of the cooling-water retention tanks 30 of each layer can be the same as or perpendicular to that of an adjacent layer of the retention tanks 30.
• all of the cooling-water retention tanks 30 are arranged in the same direction and stacked in multi-layers.
• the cooling-water retention tanks 30 can be stacked in such a way that the tanks 30 of one layer are arranged perpendicular with those of adjacent layers as illustrated in FIG. 4B.
• the cooling-water retention tanks 30 may be so stacked as to form a predetermined angle ⁇ with respect to the bottom of the containment building.
• the molten core material 5 is cooled down by the cooling- water retention tanks 30 on the first layer while flowing at the predetermined angle ⁇ and then the molten core material 5 is sequentially cooled down again by the cooling- water retention tanks 30 on the second layer this time.
• a body 31 of such a cooling- water retention tank may be made of material having a low melting point to melt when it contacts the molten core material 5 of high temperature.
• the cooling water 33 containing inert gases 32 is filled inside the cooling- water retention tanks 30. After the bodies 31 of the cooling- water retention tanks 30 are molten due to a contact with the molten core material 5 of high temperature, the molten core material 5 reacts to the cooling water 33 containing the inert gases 32. Therefore, the molten core material 5 directly interacts with the cooling water so that cooling efficiency is increased and steam explosion can be remarkably reduced.
• the method includes the step 1 of retaining the molten core material in a cavity of the containment building to restrict a passage thereof and mixing the molten core material with the glass material to lower a heat generation density.
• the step 1 is performed, at a severe accident in the nuclear power plant, by retaining the molten core material 5 releasing below the reactor vessel 10 due to meltdown of the core in a cavity of the containment building 1 to restrict a passage thereof and mixing the molten core material 5 with the glass material to lower the heat generation density first.
• the glass-material mixing part 20 has the support plate 21 installed below the reactor vessel 10.
• the support plate 21 may be inclined at a predetermined angle ⁇ so that the molten core material 5 that has passed through the reactor vessel 10 may be mixed with the glass material of the glass material layer 22 and then flow down to the lower portion of the containment building 1. Therefore, the glass material layer 22 formed in a predetermined thickness is provided to an upper surface of the support plate 21 so that the molten core material 5 may be mixed with the glass material.
• the blocking wall 23 installed at a lower end of the inclined support plate 21 prevents the glass material formed on the upper surface of the support plate 21 from flowing down in normal times, but when a severe accident occurs, is molten by the molten core material 5 of high temperature so that the molten core material 5 mixed with the glass material may flow down to the lower portion.
• the method for cooling the molten core material includes the step 2 of causing the molten core material mixed with the glass material to flow down to cooling-water retention tanks 30 stacked at the lower portion to contact cooling water 33 containing inert gases 32 in the cooling-water retention tanks 30, thereby cooling the mixed molten core material.
• the step 2 is a cooling step by the inert gases 32 and the cooling water 33.
• the molten core material 5 mixed with the glass material falls down to the cooling- water retention tanks 30 stacked below the glass-material mixing part 20, the body 31 of the cooling-water retention tanks 30 is molten when it contacts the molten core material 5 of high temperature, and the molten core material is cooled down through interaction with the cooling water 33 containing the inert gases 32 in the cooling-water retention tanks 30.
• the cooling-water retention tanks 30 form a predetermined angle ⁇ with respect to the bottom of the containment building 1, and are stacked in multi-layers.
• the molten core material 5 may be cooled down by the cooling-water retention tanks 30 in the first layer and cooled down again by the cooling-water retention tanks 30 in the second layer, and cooled down step by step by subsequently underlying layers of the cooling-water retention tanks.
• the present invention mixes the molten core material 5 with the glass material first to lower the heat generation density and then has the molten core material touched with the stacked cooling-water retention tanks 30 to cool down its temperature. Therefore, the cooling can be efficiently performed and a danger of steam explosion can be remarkably reduced.
• the invention can additionally proceed with the step 3 of: opening the valve 41 of the cooling- water supply part 40 and supplying the cooling water through the passage 42 from the cooling- water storage tank 43, thereby removing decay heat from the molten core material.
• step 3 as the valve 41 of the cooling- water supply part 40 is opened, the cooling water is supplied through the passage 42 from the cooling- water storage tank 43, so that the decay heat of the molten core material 5 can be completely removed.
• the present invention has a cooling-water supply part 40 to effectively remove decay heat, and further, recycles the cooling water, which is very effective for a long-term cooling.
• the apparatus and method for cooling the molten core material can lower the heat generation density of the molten core material 5 by mixing the molten core material 5 that has passed through the reactor vessel 10 with the glass material first, and prevent the steam explosion and effectively cool down the molten core material 5 by having the molten core material 5 flow to the cooling-water retention tanks 30 containing the inert gases.
• the present invention has the cooling- water supply part 40 to completely remove decay heat from the molten core material 5.

Landscapes

• Engineering & Computer Science (AREA)
• Polymers & Plastics (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Food Science & Technology (AREA)
• Physics & Mathematics (AREA)
• Nutrition Science (AREA)
• Health & Medical Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Plasma & Fusion (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Structure Of Emergency Protection For Nuclear Reactors (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=36751964

Family Applications (1)

Country Status (3)

Cited By (3)

Families Citing this family (6)

Citations (2)

Family Cites Families (2)

• 2004
  • 2004-02-10 KR KR1020040008768A patent/KR100549862B1/ko not_active IP Right Cessation
• 2005
  • 2005-02-07 WO PCT/KR2005/000368 patent/WO2005076284A1/en active Application Filing
  • 2005-02-07 CN CNB2005800001709A patent/CN100375200C/zh not_active Expired - Fee Related

Patent Citations (2)

Also Published As

Similar Documents

Legal Events