JP2013108772A - Melt collector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a melt collector capable of improving safety by cooling melt dropped from a reactor at an early stage.SOLUTION: A cavity 86 is formed under a pressurized water reactor 12, a collection plate 93 located under the pressurized water reactor 12 to receive melt dropped from the pressurized water reactor 12 is formed in the cavity 86, a plurality of recesses 94 are formed on the collection plat 93 at a predetermined interval, and cooling water passages 95 are formed between the plurality of recesses 94.

Description

  The present invention relates to a melt collecting device for quickly cooling a melt falling from a core when a severe accident occurs in a nuclear power plant.

  One of the nuclear power plants is a pressurized water reactor. In this pressurized water reactor, light water is used as a reactor coolant and a neutron moderator, and high-temperature and high-pressure water that does not boil throughout the primary system is used. Water is sent to a steam generator to generate steam by heat exchange, and this steam is sent to a turbine generator to generate electricity.

  In such a pressurized water reactor, the reactor containment vessel is erected on a solid ground such as a bedrock, and a plurality of compartments are partitioned inside by reinforced concrete or the like. And the reactor vessel is suspended and supported at the center by a cylindrical concrete structure that defines this compartment, and a cavity is defined below the reactor vessel. In this nuclear reactor, a predetermined number of fuel assemblies in which a predetermined number of control rods are inserted between a plurality of fuel rods and arranged in a grid are stored in the reactor vessel.

  When a loss of coolant accident (LOCA) or a transient event (transient) occurs in a nuclear power plant configured in this way, an emergency core cooling device is activated to cool the core inside the reactor vessel. The generated heat is sufficiently removed. However, if this emergency core cooling system fails, the core cannot be cooled, the core inside the reactor vessel is melted, and molten material such as molten fuel breaks the reactor vessel and penetrates the lower part. And fall into the cavity. In general, in preparation for such an accident, when the melt in the core flows out of the reactor vessel, the molten melt is received in the cavity and cooled with cooling water to ensure safety. .

  Examples of such a technique include those described in Patent Documents 1 and 2. In the core melt collection repository described in Patent Document 1, a reservoir having a bottom recess for forming a core melt collection area is provided with respect to the core melt inlet, and a separation web is provided for each bottom web. It is provided between the recesses. In the reactor containment vessel described in Patent Document 2, a cavity that can supply cooling water in an emergency is provided below the pressurized water reactor, and an inclined plate that diffuses the melt from the pressurized water reactor into this cavity. Is provided.

Japanese Patent No. 3117952 JP 2010-266286 A

  In a conventional nuclear reactor containment vessel, it is necessary to temporarily cool the fallen melt in this cavity and then remove it. And in order to cool a melt efficiently, it is desirable to separate this melt into a plurality of small deposits, hold it at predetermined intervals, and cool it. In the conventional apparatus described above, it is difficult to efficiently cool the melt by separating the melt into a plurality of small volumes at an early stage and holding the melt at a predetermined interval.

  This invention solves the subject mentioned above, and aims at providing the collection apparatus of the melt which aims at the improvement of safety | security by cooling the melt falling from a nuclear reactor at an early stage.

  In order to achieve the above object, a melt collecting apparatus of the present invention is a melt collecting apparatus provided in a cavity below a nuclear reactor, and is located below the nuclear reactor in the cavity. A collection surface for receiving the melt falling from the nuclear reactor, a plurality of recesses formed at predetermined intervals on the collection surface, and a cooling medium flow path provided between the plurality of recesses. It is characterized by.

  Therefore, in the event of an emergency, when the nuclear reactor breaks down and the melt falls into the cavity, the melt is received and diffused by the collection surface, and collected in a plurality of recesses on the collection surface. The melt as a small volume collected in the recess is cooled by the cooling medium flowing through the cooling medium flow path, and the melt falling from the nuclear reactor is separated into small volumes, and this melt is quickly removed. Cooling can improve safety.

  In the melt collecting apparatus of the present invention, the cavity includes a melt receiving area provided below the nuclear reactor, and a collecting area for collecting and cooling the melt adjacent to the receiving area. And the collection surface in the receiving region is an inclined surface inclined downward toward the collection region side, and the plurality of recesses are formed in the collection surface in the collection region. It is a feature.

  Therefore, the melt from the nuclear reactor is received by the collecting surface and diffused by moving from the receiving region to the collecting region by the inclined surface, and is collected in a plurality of recesses in the collecting region, By separating the melt into small volumes in a collection region separated from the reactor, the melt can be cooled early.

  In the melt collecting apparatus of the present invention, a collecting plate having a predetermined thickness is fixed to the upper part of the protective concrete, and the collecting surface is formed on the upper surface of the collecting plate.

  Therefore, the structure can be simplified by fixing the collecting plate to the upper part of the protective concrete and forming the collecting surface.

  In the melt collecting apparatus of the present invention, the collecting plate is configured by joining an upper plate on which the plurality of concave portions are formed and a lower plate having a planar shape, and the upper plate and the The cooling medium flow passage is formed between the lower plate and the lower plate.

  Therefore, the upper plate and the lower plate in which the recesses are formed are joined to form the collection plate, and the cooling medium flow passage is formed therebetween, thereby easily securing the cooling medium flow passage in the collection plate. It is possible to perform local cooling of the collecting plate and improve the manufacturability.

  In the melt collecting apparatus of the present invention, the collecting plate is characterized in that a heat-resistant member is fixed to the upper surface of the upper plate.

  Therefore, by fixing the heat-resistant member on the upper surface of the collection plate, damage to the collection surface due to the melt can be suppressed.

  In the melt collecting apparatus of the present invention, the plurality of recesses are arranged and formed in a staggered manner, and the cooling medium flow passage is bent and arranged avoiding the plurality of recesses.

  Therefore, the melt collected by the cooling medium can be efficiently cooled by arranging the plurality of recesses in a zigzag manner and bending the cooling medium flow path.

  In the melt collecting apparatus of the present invention, the plurality of recesses have an inverted truncated cone shape or an inverted truncated pyramid shape.

  Therefore, the cooling efficiency of the melt can be improved by enlarging the surface area by the concave portion having the inverted truncated cone shape or the inverted truncated pyramid shape.

  According to the melt collecting apparatus of the present invention, a collecting surface for receiving the melt falling from the nuclear reactor is provided, and a plurality of concave portions are formed on the collecting surface at a predetermined interval, and the plurality of concave portions are formed between the plurality of concave portions. Since the cooling medium flow passage is provided, it is possible to improve the safety by separating the melt falling from the nuclear reactor into small volumes and cooling the melt at an early stage.

FIG. 1 is a schematic configuration diagram of a melt collecting device applied to a nuclear reactor containment vessel according to Embodiment 1 of the present invention. FIG. 2 is a schematic plan view illustrating the melt collecting apparatus according to the first embodiment. FIG. 3 is a cross-sectional view of a collecting plate in the melt collecting apparatus according to the first embodiment. FIG. 4 is a schematic configuration diagram illustrating a nuclear power plant to which the reactor containment vessel of the first embodiment is applied. FIG. 5 is a cross-sectional view showing a reactor structure of a pressurized water reactor. FIG. 6 is a schematic configuration diagram of the reactor containment vessel according to the first embodiment. FIG. 7 is a plan view of a collection plate in the melt collection apparatus applied to the reactor containment vessel according to the second embodiment of the present invention. FIG. 8 is a plan view of a collection plate in the melt collection apparatus applied to the reactor containment vessel according to Example 3 of the present invention. FIG. 9 is a schematic configuration diagram of a melt collection device applied to a nuclear reactor containment vessel according to Embodiment 4 of the present invention. 10-1 is a side view illustrating a first member of the collection plate of Example 4. FIG. 10-2 is a plan view illustrating the first member of the collection plate of Example 4. FIG. FIG. 11A is a side view illustrating the second member of the collection plate of the fourth embodiment. 11-2 is a plan view illustrating a second member of the collection plate of Example 4. FIG. FIG. 12 is a plan view illustrating a connection state of the first member in the collection plate of the fourth embodiment. FIG. 13 is a plan view illustrating a collecting plate according to the fourth embodiment. 14 is a cross-sectional view of the collection plate of Example 4. FIG.

  Exemplary embodiments of a melt collecting apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this Example, Moreover, when there exists multiple Example, what comprises combining each Example is also included.

  FIG. 1 is a schematic configuration diagram of a melt collecting device applied to a reactor containment vessel according to a first embodiment of the present invention, and FIG. 2 is a schematic plan view illustrating the melt collecting device of the first embodiment. 3 is a cross-sectional view of an inclined plate in the melt collecting apparatus of Example 1, FIG. 4 is a schematic configuration diagram showing a nuclear power plant to which the reactor containment vessel of Example 1 is applied, and FIG. FIG. 6 is a schematic diagram of a reactor containment vessel according to the first embodiment.

  The nuclear reactor applied to the nuclear power plant of Example 1 uses light water as a reactor coolant and a neutron moderator to produce high-temperature and high-pressure water that does not boil over the entire primary system, and sends this high-temperature and high-pressure water to a steam generator. This is a pressurized water reactor (PWR) that generates steam by heat exchange and sends the steam to a turbine generator to generate electricity.

  That is, in the nuclear power plant having this pressurized water reactor, as shown in FIG. 4, the pressurized water reactor 12 and the steam generator 13 are stored in the reactor containment vessel 11. The furnace 12 and the steam generator 13 are connected via cooling water pipes 14 and 15, a pressurizer 16 is provided in the cooling water pipe 14, and a cooling water pump 17 is provided in the cooling water pipe 15. In this case, light water is used as the moderator and the primary cooling water, and the primary cooling system is controlled by the pressurizer 16 so as to maintain a high pressure state of about 160 atm in order to suppress boiling of the primary cooling water in the core. Yes. Therefore, in the pressurized water reactor 12, light water is heated as primary cooling water using low-enriched uranium or MOX as fuel, and the high-temperature primary cooling water is maintained at a predetermined high pressure by the pressurizer 16 through the cooling water pipe 14. It is sent to the steam generator 13. In the steam generator 13, heat exchange is performed between the high-pressure and high-temperature primary cooling water and the secondary cooling water, and the cooled primary cooling water is returned to the pressurized water reactor 12 through the cooling water pipe 15.

  The steam generator 13 is connected to a turbine 18 and a condenser 19 provided outside the reactor containment vessel 11 through cooling water pipes 20 and 21, and a water supply pump 22 is provided in the cooling water pipe 21. ing. Further, a generator 23 is connected to the turbine 18, and a condenser pipe 19 is connected to a water intake pipe 24 and a drain pipe 25 for supplying and discharging cooling water (for example, seawater). Accordingly, the steam generated by exchanging heat with the high-pressure and high-temperature primary cooling water in the steam generator 13 is sent to the turbine 18 through the cooling water pipe 20, and the turbine 18 is driven by this steam to generate the generator 23. To generate electricity. The steam that has driven the turbine 18 is cooled by the condenser 19, and then returned to the steam generator 13 through the cooling water pipe 21.

  Further, in the pressurized water reactor 12, as shown in FIG. 5, the reactor vessel 41 has a reactor vessel main body 42 and a reactor vessel mounted on the upper portion thereof so that the internal structure can be inserted therein. A lid (upper mirror) 43 is configured, and the reactor vessel lid 43 is fixed to the reactor vessel body 42 by a plurality of stud bolts 44 and nuts 45 so as to be opened and closed.

  The reactor vessel main body 42 has a cylindrical shape in which the upper portion can be opened by removing the reactor vessel lid 43 and the lower portion is closed by a lower mirror 46 having a spherical shape. The reactor vessel main body 42 is formed with an inlet nozzle (inlet nozzle) 47 for supplying light water (coolant) as primary cooling water and an outlet nozzle (exit nozzle) 48 for discharging light water on the upper part. Yes. In addition to the inlet nozzle 47 and the outlet nozzle 48, the reactor vessel main body 42 is formed with a water injection nozzle (water injection pipe stand) (not shown).

  In the reactor vessel main body 42, an upper core support plate 49 is fixed above the inlet nozzle 47 and the outlet nozzle 48, while a lower core support plate 50 is fixed near the lower mirror 46 below. Has been. The upper core support plate 49 and the lower core support plate 50 have a disk shape and are formed with a number of communication holes (not shown). The upper core support plate 49 is connected to an upper core plate 52 formed with a plurality of communication holes (not shown) below via a plurality of core support rods 51.

  In the reactor vessel main body 42, a cylindrical core tank 53 having a cylindrical shape is disposed with a predetermined gap from the inner wall surface. The core tank 53 is connected to the upper core plate 52 at the upper part, and has a disk shape at the lower part. The lower core plate 54 in which a large number of communication holes (not shown) are formed is connected. The lower core plate 54 is supported by the lower core support plate 50. That is, the core tank 53 is suspended and supported by the lower core support plate 50 of the reactor vessel main body 42.

  The core 55 is formed by an upper core plate 52, a core tank 53, and a lower core plate 54. The core 55 has a large number of fuel assemblies 56 disposed therein. Although not shown, the fuel assembly 56 is configured by bundling a large number of fuel rods in a lattice shape by a support lattice, and an upper nozzle is fixed to the upper end portion and a lower nozzle is fixed to the lower end portion. The core 55 has a large number of control rods 57 arranged therein. The large number of control rods 57 are combined at the upper end portion into a control rod cluster 58 that can be inserted into the fuel assembly 56. A number of control rod cluster guide tubes 59 are fixed to the upper core support plate 49 so as to pass through the upper core support plate 49, and the lower end portion of each control rod cluster guide tube 59 is controlled in the fuel assembly 56. It extends to the bar cluster 58.

  The reactor vessel lid 43 constituting the reactor vessel 41 is provided with a control jack drive device 60 of a magnetic jack at the upper portion, and is accommodated in a housing 61 that is integrated with the reactor vessel lid 43. A large number of control rod cluster guide tubes 59 are extended at the upper end to the control rod drive device 60, and the control rod cluster drive shaft 62 extends from the control rod drive device 60 in the control rod cluster guide tube 59. It extends to the fuel assembly 56 and can grip the control rod cluster 58.

  The control rod driving device 60 extends in the vertical direction and is connected to the control rod cluster 58, and a plurality of circumferential grooves are arranged on the surface thereof at equal pitches in the longitudinal direction. The power of the reactor is controlled by moving up and down with a magnetic jack.

  The reactor vessel main body 42 is provided with a number of instrumentation nozzles 63 penetrating the lower mirror 46. Each instrumentation nozzle 63 has an in-reactor instrumentation guide pipe 64 fixed to the upper end portion inside the reactor. On the other hand, a conduit tube 65 is connected to the lower end portion outside the furnace. Each in-core instrumentation guide tube 64 has an upper end connected to the lower core support plate 50, and upper and lower connecting plates 66 and 67 for suppressing vibration are attached. The thimble tube 68 is equipped with a neutron flux detector (not shown) capable of measuring a neutron flux, passes from the conduit tube 65 through the instrumentation nozzle 63 and the in-core instrumentation guide pipe 64, and passes through the lower core plate 54. The fuel assembly 56 can be inserted through.

  Accordingly, the control rod cluster drive shaft 62 is moved by the control rod drive device 60 and the control rod 57 is inserted into the fuel assembly 56, thereby controlling the nuclear fission in the reactor core 55 and the generated thermal energy to the reactor vessel. The light water filled in 41 is heated, and high-temperature light water is discharged from the outlet nozzle 48 and sent to the steam generator 13 as described above. That is, the nuclear fuel constituting the fuel assembly 56 is fissioned to release neutrons, and the light water as the moderator and the primary cooling water reduces the kinetic energy of the released fast neutrons to become thermal neutrons, and new It is easy to cause nuclear fission and takes away the generated heat to cool. Further, by inserting the control rod 57 into the fuel assembly 56, the number of neutrons generated in the core 55 is adjusted, and the control rod 57 is rapidly inserted into the core 55 when the reactor is urgently stopped.

  In the reactor vessel 41, an upper plenum 69 communicating with the outlet nozzle 48 is formed above the core 55, and a lower plenum 70 is formed below. A downcomer portion 71 that communicates with the inlet nozzle 47 and the lower plenum 70 is formed between the reactor vessel 41 and the reactor core 53. Accordingly, the light water flows into the reactor vessel main body 42 from the inlet nozzle 47, flows down the downcomer portion 71 and reaches the lower plenum 70, and is guided upward by the spherical inner surface of the lower plenum 70. Then, after passing through the lower core support plate 50 and the lower core plate 54, it flows into the core 55. The light water that has flowed into the core 55 absorbs heat energy generated from the fuel assemblies 56 constituting the core 55 to cool the fuel assemblies 56, and at the same time passes through the upper core plate 52 at a high temperature. Ascending to the upper plenum 69 and discharged through the outlet nozzle 48.

  As shown in FIG. 6, the nuclear reactor power plant containment vessel 11 described above is erected on a solid ground 81 such as a bedrock via a steel plate liner 82 that forms a pressure boundary with the outside, and is internally formed by reinforced concrete or the like. A plurality of compartments, for example, an upper compartment 83 and a steam generator loop chamber 84 are defined. A concrete structure 85 having a cylindrical shape that defines a steam generator loop chamber 84 is formed in the central portion of the reactor containment vessel 11, and the pressurized water reactor 12 (reactor container) is formed by the concrete structure 85. 41) is suspended and supported. The steam generator 13 is disposed in the steam generator loop chamber 84 and is connected by cooling water pipes 14 and 15.

  Further, in the reactor containment vessel 11, a cavity 86 is defined by the concrete structure 85 located below the reactor vessel 41, and this cavity 86 is connected to the steam generator loop via the drain line 87. It communicates with the chamber 84. The reactor containment vessel 11 is provided with a fuel replacement water pit 88. In an emergency, a coolant cooling path (cooling) for supplying the cooling water of the fuel replacement water pit 88 to the pressurized water reactor 12 for cooling is provided. A water supply device) 89 and a reactor containment vessel cooling path (cooling water supply device) 90 for spraying and cooling cooling water to the reactor containment vessel 11 are provided. Then, the cooling water sprayed in the reactor containment vessel 11 is stored in the cavity 86 from the steam generator loop chamber 84 through the drain line 87.

  Although not shown, the reactor containment vessel 11 is provided with an external injection path such as fire extinguishing water for supplying cooling water to the cavity 86, and the base end portion of the external injection path is outside the reactor containment vessel 11. While connected to an external supply facility such as fire extinguishing water installed at the top, the tip portion communicates with the cavity 86.

  In the reactor containment vessel 11 configured as described above, in this embodiment, a cavity 86 capable of supplying cooling water is provided below the pressurized water reactor 12, and the pressurized water atom is provided in the cavity 86 in an emergency. A collecting device 91 that receives and cools the molten material dropped from the furnace 12 is provided.

  When a loss of coolant accident (LOCA) or the like occurs in a nuclear power plant, an emergency core cooling device is activated and cooling water is supplied into the reactor cooling facility including the pressurized water reactor 12 to cool the core. Thoroughly remove generated heat. However, if this emergency core cooling system fails, the core cannot be cooled, the core inside the reactor vessel is melted, and molten material such as molten fuel breaks the reactor vessel and penetrates the lower part. Then, it falls into the cavity 86. At this time, cooling water can be supplied to the cavity 86, and the melt falling into the cavity 86 is cooled by the cooling water. However, the melt that has fallen into the cavity 86 is finely granulated or solidified by the interaction with the cooling water. However, when the solid debris accumulates in a mountain shape, the inside should be sufficiently cooled. It becomes difficult.

  The collection device 91 of the present embodiment receives the melt dropped from the pressurized water reactor 12 and separates and diffuses the melt into a small volume, thereby increasing the surface area of the melt and improving the cooling efficiency.

  In this collection device 91, as shown in FIGS. 1 to 3, the cavity 86 is formed below the pressurized water reactor 12 by the concrete structure 85. The cavity 86 has a horizontal hole shape extending from the lower side of the pressurized water reactor 12 to one side in the horizontal direction, the proximal end portion is located below the pressurized water reactor 12, and the distal end side is the pressurized water reactor 12. It is spaced apart from below. In this case, the cavity 86 communicates with the steam generator loop chamber 84 (see FIG. 6) through the drain line 87 at the upper end on the tip side.

  In the cavity 86, a protective concrete 85a for protecting the steel liner 82 is provided on the upper portion of the steel liner 82, and a collecting device 91 is disposed on the upper surface of the protective concrete 85a. That is, the cavity 86 has a melt receiving area 86a provided below the pressurized water reactor 12, and a collection area 86b adjacent to the receiving area 86a for diffusing and cooling the melt. The area 86 a and the collection area 86 b are communicated with each other through the communication path 92. The communication passage 92 has a passage area that is narrower than the passage areas of the receiving region 86a and the collection region 86b.

  In the receiving area 86a including the communication path 92, the upper surface of the protective concrete 85a is an inclined surface 85b, and the upper surface of the collection area 86b is a horizontal plane 85c. The collection plate 93 constituting the collection device 91 is fixed to the upper surface portion of the protective concrete 85 a, and the upper surface constitutes a collection surface for receiving the melt falling from the pressurized water reactor 12. In the collection plate 93, an inclined surface 93a is formed in an area from the receiving area 86a to the communication path 92, and an area of the collection area 86b is a horizontal plane 93b. The inclined surface 93a is inclined downward toward the collection region 86b.

  Further, the collecting plate 93 is formed with a plurality of concave portions 94 arranged in a staggered pattern at predetermined intervals on a horizontal surface 93b corresponding to the collecting region 86b. The recesses 94 are arranged adjacent to each other at equal intervals, and are formed in contact with the wall surface of the cavity 86. The collecting plate 93 is provided with a cooling water flow passage (cooling medium flow passage) 95 between the plurality of recesses 94. The cooling water flow passage 95 is arranged inside the collection plate 93 in the front-rear and left-right directions, and all of them are in communication. The cooling water flow passage 95 is connected to a cooling water circulation path (not shown), and in the event of an emergency, when a coolant loss accident or the like occurs, the pump is driven and the cooling water stored in the cavity 86 flows from the cooling water circulation path. While being able to circulate through the passage 95, the cooling water circulated by the heat exchanger can be cooled.

  That is, the collection plate 93 is configured by joining an upper plate 96 in which a plurality of concave portions 94 are formed and a lower plate 97 having a planar shape, and is cooled between the upper plate 96 and the lower plate 97. A water flow passage 95 is formed. The collection plate 93 has a heat-resistant member 98 fixed to the upper surface of the upper plate 96. In this case, the upper plate 96 is formed with a plurality of concave portions 94 by, for example, pressing, and is fixed to the lower plate 97 using welding, bolts, or the like. The heat-resistant member 98 is a ceramic molded body, for example, and is fixed to the upper plate 96 with an adhesive or the like.

  The plurality of recesses 94 formed in the collection plate 93 has an inverted truncated cone shape. In this case, the concave portion 94 has an inverted truncated cone shape or an inverted truncated pyramid shape (for example, a quadrangular pyramid shape) for the purpose of increasing the surface area, and may be, for example, a spherical shape.

  Therefore, when an accident occurs, as shown in FIG. 6, a pump (not shown) is driven, and the cooling water stored in the fuel replacement water pit 88 is sent through the reactor containment vessel cooling path 90, and atoms are injected from a number of injection nozzles. Cooling water is sprayed into the furnace containment vessel 11. Then, this cooling water is sprayed with respect to a large amount of steam generated in the reactor containment vessel 11. Here, a large amount of energy is taken away and the inside of the reactor containment vessel 11 is cooled and then the temperature is increased. And is stored in the cavity 86 through the drain line 87 from the steam generator loop chamber 84. The energy released into the reactor containment vessel 11 can be taken away by the sprayed cooling water, and the integrity of the reactor containment vessel 11 can be maintained.

  Further, when an accident occurs, a pump (not shown) is driven, and the cooling water stored in the fuel replacement water pit 88 is sent from the reactor cooling path 89 to the pressurized water reactor 12. Then, this cooling water takes away the decay heat of the core generated in the core in the pressurized water reactor 12, a part of it becomes steam and is released to the atmosphere of the reactor containment vessel 11, and the rest becomes high-temperature water. Then, it flows out to the outside and is stored in the cavity 86 through the drain line 87 from the steam generator loop chamber 84.

  By the way, if the above-described emergency core cooling device breaks down, the cooling water cannot be sent to the pressurized water reactor 12 to be cooled, the core inside the reactor vessel is melted, and the melt causes the reactor vessel 41 to melt. It is broken and falls into the cavity 86. Even when the emergency core cooling device fails, it is possible to supply cooling water to the reactor containment vessel 11 or the pressurized water reactor 12 through at least one of the paths 89 and 90, and this cooling water is supplied to the cavity 86. Can be supplied to. Further, the reactor containment vessel 11 is provided with an external injection path such as fire-extinguishing water that supplies cooling water directly to the cavity 86, and cooling water can be supplied to the cavity 86 using this external injection path. . Therefore, even if the emergency core cooling device breaks down, the cavity 86 can be flooded with cooling water.

  Then, as shown in FIGS. 1 to 3, the molten material dropped from the pressurized water reactor 12 in the collecting device 91 falls onto the upper surface portion of the collecting plate 93 in the receiving region 86 a of the cavity 86. During the fall, the debris finely divided by the interaction with the cooling water stored in the cavity 86 falls on the inclined plate 93 to form a debris bed. The debris bed is diffused while moving in the cavity 86 due to the inclination of the collection plate 93.

  In other words, the melt that has fallen on the collection plate 93 in the receiving area 86a moves to the collection area 86b through the communication path 92 by the inclined surface 93a. Here, since the collection plate 93 in the collection region 86b has a large number of recesses 94 formed on the surface, a plurality of melts on the collection plate 93 are arranged at equal intervals in the collection region 86b. Are collected in the recesses 94 of the slab and separated into small volumes. And since the cooling water has circulated through the cooling water flow path 95 provided in the inside of the collection plate 93, the melt which became the small volume collected by the some recessed part 94 is this cooling water. It is cooled by. In addition, the small volume melt collected in each of the concave portions 94 is cooled by being removed by the surrounding cooling water.

  As described above, in the melt collecting apparatus according to the first embodiment, the cavity 86 is provided below the pressurized water reactor 12, and the pressurized water reactor is located in the cavity 86 below the pressurized water reactor 12. A collecting plate 93 for receiving the melt falling from 12 is provided, a plurality of recesses 94 are formed in the collecting plate 93 at predetermined intervals, and a cooling water flow passage 95 is provided between the plurality of recesses 94.

  Accordingly, when the pressurized water reactor 12 is damaged and the molten material falls into the cavity 86 in an emergency of the nuclear power plant, the molten material is received by the collecting plate 93 and diffused. Are collected in the concave portion 94. Therefore, the melt as a small volume collected in the plurality of recesses 94 is cooled by the cooling water flowing through the cooling water flow passage 95, and the melt falling from the pressurized water reactor 12 is reduced to the small volume. It is possible to improve safety by cooling the melt as a small volume at an early stage.

  In the melt collecting apparatus according to the first embodiment, the melt is collected in the cavity 86 adjacent to the melt receiving region 86a located below the pressurized water reactor 12 and the receiving region 96a. A collection region 96b to be cooled is provided, an inclined surface 93a inclined to the collection region side 86b side is formed on the collection plate 93 in the receiving region 86a, and a plurality of recesses 94 are formed in the collection plate 93 in the collection region 86b. doing. Therefore, the melt from the pressurized water reactor 12 is received by the inclined surface 93a, diffused by moving from the receiving area 86a to the collecting area 86b, and collected by the plurality of recesses 94 in the collecting area 86b. The Rukoto. Therefore, this melt can be cooled early by separating the melt into small volumes in the collection region 86b spaced from the pressurized water reactor 12.

  Moreover, in the molten material collection apparatus of Example 1, the collection board 93 of predetermined thickness is fixed to the upper part of the protective concrete 85a, a collection surface is formed in the upper surface of the collection board 93, and several recessed part 94 is formed. Is forming. Therefore, the structure can be simplified by fixing the collection plate 93 to the upper part of the protective concrete 85a and forming the plurality of recesses 94.

  In the melt collecting apparatus according to the first embodiment, the upper plate 96 formed with a plurality of recesses 94 and the lower plate 97 having a planar shape are joined to form the collecting plate 93, and the upper plate 96. A cooling water flow passage 95 is formed between the lower plate 97 and the lower plate 97. Therefore, the cooling water flow passage 95 can be easily secured in the collection plate 93, and the manufacturability can be improved.

  In the melt collecting apparatus according to the first embodiment, the heat-resistant member 98 is fixed to the upper surface of the collecting plate 93. Therefore, damage to the collection plate 93 due to the melt can be suppressed.

  In the melt collecting apparatus according to the first embodiment, the plurality of concave portions 94 have an inverted truncated cone shape or an inverted truncated pyramid shape. Therefore, the cooling efficiency of the melt can be improved by enlarging the surface area by the concave portion 94 having an inverted frustoconical shape.

  FIG. 7 is a plan view of a collection plate in the melt collection apparatus applied to the reactor containment vessel according to the second embodiment of the present invention. The basic structure of the melt collecting apparatus of the present embodiment is substantially the same as that of the above-described embodiment 1, and will be described with reference to FIG. 1 and has the same functions as those of the above-described embodiment. The members having the same reference numerals are given the detailed descriptions thereof.

  In the second embodiment, as shown in FIGS. 1 and 7, a cavity 86 capable of supplying cooling water is provided below the pressurized water reactor 12, and the cavity 86 falls from the pressurized water reactor 12 in an emergency. A collecting device 101 is provided for receiving and cooling the molten material. The collection device 101 receives the melt dropped from the pressurized water reactor 12 and separates and diffuses the melt into a small volume, thereby increasing the surface area of the melt and improving the cooling efficiency.

  In the collection device 101, the cavity 86 is formed below the pressurized water reactor 12 by the concrete structure 85. The cavity 86 includes a melt receiving region 86a provided below the pressurized water reactor 12, and a collection region 86b adjacent to the receiving region 86a for diffusing and cooling the melt. 86 a and the collection region 86 b communicate with each other through the communication path 92.

  In the protective concrete 85a, the collection plate 102 constituting the collection device 101 is fixed to the upper surface portion, the area from the receiving area 86a to the communication path 92 is an inclined surface, and the area of the collection area 86b is a horizontal plane. is there. The collection plate 102 is formed with a plurality of recesses 103 arranged in a staggered pattern at predetermined intervals at positions corresponding to the collection region 86b. The collecting plate 102 is provided with a cooling water flow passage (cooling medium flow passage) 104 located between the plurality of recesses 103 inside.

  The cooling water flow passage 104 is bent and arranged so as to avoid the plurality of concave portions 103 arranged in a staggered manner. In this case, it is desirable that the cooling water flow passage 104 is not a space portion between the upper plate 96 and the lower plate 97 but a pipe provided in this space portion as in the first embodiment. The cooling water flow passage 104 is connected to a cooling water circulation path (not shown). When an accident of loss of coolant occurs in an emergency, the pump is driven to cool the cooling water stored in the cavity 86 from the cooling water circulation path. While being able to circulate to the water flow path 95, the cooling water circulated by the heat exchanger can be cooled.

  Therefore, if the emergency core cooling device breaks down, the cooling water cannot be sent to the pressurized water reactor 12 for cooling, the core inside the reactor vessel 41 is melted, and the melt breaks the reactor vessel 41. To fall into the cavity 86. Even when the emergency core cooling device fails, it is possible to supply cooling water to the reactor containment vessel 11 or the pressurized water reactor 12 through at least one of the paths 89 and 90, and this cooling water is supplied to the cavity 86. Can be supplied to.

  Then, the molten material that has fallen from the pressurized water reactor 12 by the collection device 101 falls to the upper surface portion of the collection plate 102 in the receiving region 86 a of the cavity 86. The melt that has fallen on the collection plate 102 in the receiving area 86a moves to the collection area 86b through the communication path 92 by the inclined surface. Here, the melt on the collection plate 102 is collected in a plurality of recesses 103 arranged at equal intervals and separated into small volumes. Then, the melt that has become a small volume collected in the plurality of recesses 103 is cooled by the cooling water flowing through the cooling water flow passage 104 in the collection plate 103. In addition, the small volume melt collected in each of the recesses 103 is cooled by being removed by the surrounding cooling water.

  As described above, in the melt collecting apparatus according to the second embodiment, the cavity 86 is provided below the pressurized water reactor 12, and the pressurized water reactor is located below the pressurized water reactor 12 in the cavity 86. 12 is provided with a collecting plate 102 for receiving the melt falling from the substrate 12, and a plurality of concave portions 103 are arranged in a staggered pattern at a predetermined interval on the collecting plate 102, and a plurality of concave portions 103 are avoided between the plurality of concave portions 103. The cooling water flow passage 104 is provided by bending.

  Therefore, when the pressurized water reactor 12 is damaged and the melt falls into the cavity 86 in an emergency of the nuclear power plant, the melt is received by the collecting plate 102 and diffused, and a plurality of the melts in the collecting plate 102 are dispersed. Are collected in the concave portion 103 of Therefore, the melt as a small volume collected in the plurality of recesses 103 is cooled by the cooling water flowing through the cooling water flow passage 104, and the melt falling from the pressurized water reactor 12 is reduced to the small volume. It is possible to improve safety by cooling the melt as a small volume at an early stage. Further, by providing the cooling water flow passage 104 by bending between the plurality of recesses 103 while avoiding this, the melt collected in the plurality of recesses 103 can be efficiently cooled by the cooling water.

  FIG. 8 is a plan view of a collection plate in the melt collection apparatus applied to the reactor containment vessel according to Example 3 of the present invention. The basic configuration of the melt collecting apparatus of the present embodiment is substantially the same as that of the first and second embodiments described above, and members having similar functions are denoted by the same reference numerals. Detailed description is omitted.

  In the third embodiment, as shown in FIG. 8, in the collection device 111, the collection plate 112 is formed with a plurality of recesses 113 arranged in a staggered manner at a predetermined interval, and a plurality of recesses 113 inside. A cooling water flow passage (cooling medium flow passage) 114 is provided between the two. This cooling water flow passage 114 is arranged in a straight line between the plurality of recesses 103 arranged in a staggered manner. In this case, the cooling water flow passage 114 is not a space portion between the upper plate 96 and the lower plate 97 as in the first embodiment, but is a pipe provided in this space portion.

  As described above, in the melt collecting apparatus according to the third embodiment, the cavity 86 is provided below the pressurized water reactor 12, and the pressurized water reactor is located in the cavity 86 below the pressurized water reactor 12. 12 is provided with a collecting plate 112 for receiving the molten material falling from the plurality of recesses 113 in a staggered manner at predetermined intervals on the collecting plate 112, and a cooling water flow is formed in a straight line between the plurality of recesses 113. A passage 114 is provided.

  Accordingly, when the pressurized water reactor 12 is damaged and the melt falls into the cavity 86 in an emergency of the nuclear power plant, the melt is received by the collecting plate 112 and diffused, and a plurality of the melts on the collecting plate 112 are dispersed. Are collected in the concave portion 113 of Therefore, the melt as a small volume collected in the plurality of recesses 113 is cooled by the cooling water flowing through the cooling water flow passage 114, and the melt falling from the pressurized water reactor 12 is reduced to the small volume. It is possible to improve safety by cooling the melt as a small volume at an early stage. Further, by providing the cooling water flow passage 104 in a straight line between the plurality of recesses 103, it is not necessary to bend the cooling water flow passage 104, and the structure can be simplified and the cost can be reduced.

  FIG. 9 is a schematic configuration diagram of a melt collecting device applied to a reactor containment vessel according to a fourth embodiment of the present invention, and FIG. 10-1 represents a first member of the collecting plate of the fourth embodiment. Side view, FIG. 10-2 is a plan view showing the first member of the collecting plate of Example 4, FIG. 11-1 is a side view showing the second member of the collecting plate of Example 4, FIG. 2 is a plan view showing a second member of the collecting plate of Example 4, FIG. 12 is a plan view showing a connected state of the first member in the collecting plate of Example 4, and FIG. FIG. 14 is a plan view showing the collection plate, and FIG. 14 is a cross-sectional view of the collection plate of Example 4.

  In Example 4, as shown in FIG. 9, a cavity 86 is provided below the pressurized water reactor 12, and the cavity 86 receives and cools the melt that has dropped from the pressurized water reactor 12 in an emergency. A collection device 121 is provided. The collection plate 122 constituting the collection device 121 is horizontally fixed to the upper surface portion of the protective concrete, and the upper surface constitutes a collection surface for receiving the melt falling from the pressurized water reactor 12. . The collection plate 122 has a plurality of recesses 123 formed in a horizontal plane.

  As shown in FIG. 14, the collection plate 122 includes a first member 131, a second member 132, and a third member 134. As illustrated in FIGS. 10A and 10B, the first member 131 is formed with a concave portion 131a that opens to the side by bending a plate material having a predetermined size. Further, as shown in FIGS. 11A and 11B, the second member 132 is formed with a concave portion 132a that opens to the side by bending a plate material having a predetermined size. In this case, the second member 132 has a horseshoe shape in which the recess 132a is wide.

  First, as shown in FIG. 12, the first member 131 is connected by welding so as to be spread in all directions along the horizontal direction, thereby forming a predetermined size, and through holes 133 are formed at staggered positions. In this case, the through-hole 133 is formed in the inclined surface which the 1st member 131 opposes. Next, as shown in FIG. 13, each through-hole 133 is formed on the first member 131 connected in plurality, and the second member 132 is placed and fixed corresponding to the position. In this case, the second member 132 closes the through hole 133. Subsequently, the third member 134 having a flat plate shape is fixed under the plurality of first members 131 connected to each other. As a result, the position corresponding to the connecting portion of the first members 131 and the second member 132 becomes the concave portion 123, and a cooling water flow passage (cooling medium flow passage) 135 is formed between the concave portions 123. .

  As described above, in the melt collecting apparatus according to the fourth embodiment, the cavity 86 is provided below the pressurized water reactor 12, and the pressurized water reactor is located below the pressurized water reactor 12 in the cavity 86. 12 is provided with a collecting plate 122 for receiving the molten material falling from 12, a plurality of concave portions 123 are arranged in a staggered manner at predetermined intervals on the collecting plate 122, and a cooling water flow passage 135 is provided between the plurality of concave portions 133. Yes.

  Accordingly, when the pressurized water reactor 12 is damaged and the melt falls into the cavity 86 in an emergency of the nuclear power plant, the melt is received by the collecting plate 122 and diffused. Are collected in the concave portion 123 of Therefore, the melt as a small volume collected in the plurality of recesses 123 is cooled by the cooling water flowing through the cooling water flow passage 135, and the melt falling from the pressurized water reactor 12 is reduced to the small volume. It is possible to improve safety by cooling the melt as a small volume at an early stage. Further, by configuring the collection plate 122 from the first member 131, the second member 132, and the third member 134, the collection plate 122 can be easily manufactured, and the cost can be reduced. Can do.

  In each of the above-described embodiments, the shape of the cavity 86 is a horizontal hole shape extending from one side of the pressurized water reactor 12 to one side in the horizontal direction. However, the shape is not limited to this shape. A shape extending from one side to the other in the horizontal direction from the lower side of the type reactor 12 or a disk shape larger than the outer diameter of the pressurized water reactor 12 may be used. Further, although the receiving area 86a and the collection area 86b are communicated with each other by the communication path 92 in the cavity 86, the receiving area 86a and the collection area 86b may be integrated into a space.

  Moreover, in each Example mentioned above, although the collection plates 93,102,112,122 were provided above the concrete structure 85, you may provide an inclined part directly in the upper surface part of the concrete structure 85, The upper surface of the concrete structure 85 may be a collection surface. Furthermore, although the recessed portions 94, 103, 113, 123 are provided in part or all of the collection plates 93, 102, 112122, the positions to be provided are not limited to the embodiment. Moreover, although the collection plates 93, 102, 112, and 122 are composed of an inclined surface and a horizontal surface, all of them may be inclined surfaces.

  In each of the above-described embodiments, the cooling water is stored in the cavity 86. However, the cooling water may not be supplied when the nuclear power plant is normal, and may be supplied in an emergency of the nuclear power plant.

  In each of the above-described embodiments, the melt collecting apparatus of the present invention has been described as applied to a pressurized water reactor. However, the present invention can also be applied to a boiling water reactor (BWR). If so, it may be applied to any nuclear reactor.

DESCRIPTION OF SYMBOLS 11 Reactor containment vessel 12 Pressurized water reactor 13 Steam generator 85 Concrete structure 85a Protective concrete 85b Inclined surface 85c Horizontal surface 86 Cavity 86a Receiving area 86b Collection area 91,101,111 Collection apparatus 92 Communication path 93,102, 112,122 Collection plate (collection surface)
94, 103, 113, 123 Recess 95, 104, 114, 135 Cooling water flow passage (cooling medium flow passage)

Claims (7)

A melt collector provided in a cavity below a nuclear reactor,
A collection surface for receiving the melt falling from the reactor located below the reactor in the cavity;
A plurality of recesses formed at predetermined intervals on the collecting surface;
A cooling medium flow path provided between the plurality of recesses;
An apparatus for collecting a melt, comprising:   The cavity has a melt receiving area provided below the reactor, and a collecting area for collecting and cooling the melt adjacent to the receiving area, and the collecting surface in the receiving area Is an inclined surface that inclines downward toward the collection region, and the plurality of recesses are formed on the collection surface in the collection region. Collection device.   The molten material collection according to claim 1, wherein a collection plate having a predetermined thickness is fixed to an upper portion of the protective concrete, and the collection surface is formed on an upper surface of the collection plate. apparatus.   The collection plate is configured by joining an upper plate in which the plurality of recesses are formed and a lower plate having a planar shape, and the cooling medium flow path is provided between the upper plate and the lower plate. The melt collecting device according to claim 3, wherein the melt collecting device is formed.   The melt collecting apparatus according to claim 4, wherein a heat-resistant member is fixed to the upper surface of the upper plate.   The plurality of recesses are arranged and formed in a staggered manner, and the cooling medium flow path is bent and arranged avoiding the plurality of recesses. Melt collector.   The melt collecting device according to any one of claims 1 to 6, wherein the plurality of concave portions have an inverted truncated cone shape or an inverted truncated pyramid shape.

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