JP2013096700A - Molten material collector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molten material collector capable of improving safety by early cooling molten materials dropped from a reactor.SOLUTION: A cavity 86 is formed under a pressurized water reactor 12, a ramp 93 for diffusing molten materials dropped from the pressurized water reactor 12 is arranged in the bottom of the cavity 86 so as to be located under the pressurized water reactor 12, and a plurality of spherical recesses 94 are formed on the ramp 93 in a staggered manner at a predetermined interval.

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. An inclined surface for diffusing the melt falling from the nuclear reactor, and a plurality of spherical concave portions formed in a staggered pattern at predetermined intervals on the inclined surface.

  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 inclined surface, and flows along the inclined surface. It is collected in the spherical concave portion, and the melt falling from the nuclear reactor is separated into small volumes, and the melt can be cooled early to improve safety.

  In the melt collecting apparatus of the present invention, the cavity has a melt receiving area provided below the nuclear reactor and a collecting area for diffusing and cooling the melt adjacent to the receiving area. The inclined surface is inclined downward in a first direction of transition from the receiving area to the collecting area, and the plurality of spherical concave portions are provided at least in the collecting area. .

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

  In the melt collecting apparatus of the present invention, the receiving area and the collecting area are communicated with each other through a communication path narrower than a passage area of the receiving area and the collecting area.

  Therefore, the melt from the nuclear reactor falls to the receiving region, moves to the collection region through the communication path narrower than the passage area, and is collected in the plurality of spherical recesses. It becomes possible to guide to the spherical recess appropriately, and the melt can be cooled early.

  In the melt collecting apparatus of the present invention, the communication path or the collecting region is widened in the first direction.

  Therefore, the melt from the nuclear reactor spreads in the width direction while moving from the receiving area to the communication path or the collection area, and this melt can be properly guided to a plurality of spherical recesses. Can be cooled early.

  In the melt collecting apparatus of the present invention, the inclined surface is inclined downward toward the first direction away from the communication path, and is directed to a second direction intersecting the first direction. It is characterized by tilting downward.

  Therefore, the melt from the nuclear reactor is received by the inclined surface, and moves widely from the receiving area to the collection area and moves in the width direction of the collection area. It becomes possible to guide to the spherical recess appropriately, and the melt can be cooled early.

  In the melt collecting apparatus of the present invention, a cooling water supply device capable of supplying cooling water to the cavity is provided.

  Accordingly, the melt that has become a small volume collected in the plurality of spherical concave portions is efficiently cooled by the cooling water, and the melt can be cooled early.

  In the melt collecting apparatus of the present invention, the inclined surface is provided with a space below, and the cooling water supply device can supply cooling water to the space.

  Therefore, the melt that has become a small volume collected in the plurality of spherical recesses is cooled by the cooling water not only from above but also from below, and the melt can be cooled early.

  According to the melt collecting apparatus of the present invention, an inclined surface for diffusing the melt falling from the reactor is provided, and a plurality of spherical recesses are formed in a staggered pattern at predetermined intervals on the inclined surface. It is possible to improve the safety by separating the molten material falling into a small volume and cooling the molten material 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. 3 is a cross-sectional view taken along the line III-III in FIG. 2 illustrating the melt collecting apparatus of 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 schematic configuration diagram of a melt collecting device applied to a reactor containment vessel according to Embodiment 2 of the present invention. FIG. 8 is a schematic plan view illustrating the melt collecting apparatus according to the second embodiment. FIG. 9 is a schematic configuration diagram of a melt collecting device applied to a nuclear reactor containment vessel according to Embodiment 3 of the present invention. FIG. 10 is a schematic configuration diagram of a melt collecting device applied to a nuclear reactor containment vessel according to Embodiment 4 of the present invention.

  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 taken along the line III-III of FIG. 2 showing the melt collecting apparatus of the first embodiment, and FIG. 4 is a schematic configuration diagram showing 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, and FIG. 6 is a schematic configuration diagram of the reactor containment vessel of 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 reactor core 53 having a cylindrical shape is disposed with a predetermined gap from an inner wall surface. The reactor core 53 is connected to an upper core plate 52 at an upper portion and a disk shape at a lower portion. 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.

  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.

  The upper surface of the protective concrete 85a is an inclined surface 85b, and an inclined plate 93 as an inclined surface for diffusing the melt falling from the pressurized water reactor 12 constituting the collection device 91 is inclined to the protective concrete 85a. It is fixed to the surface 85b. The inclined plate 93 extends from the receiving area 86a to the collection area 86b through the communication path 92. The inclined plate 93 has an upper surface (inclined surface) inclined downward in the first direction A from the receiving region 86a toward the collection region 86b.

  Further, the inclined plate 93 has a plurality of spherical recesses 94 arranged in a staggered pattern at predetermined intervals on the upper surface (inclined surface) in the collection region 86b. Adjacent ones of the spherical recesses 94 are arranged at equal intervals, and are formed in contact with the wall surface of the cavity 86.

  In this case, the collection area 86 b has its passage width widened from the communication passage 92 in the first direction A. In addition, the inclined plate 93 is inclined downward from the communication path 92 toward the first direction A, and is inclined downward toward the second direction B intersecting (orthogonal to) the first direction A. Yes.

  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 for cooling, the core inside the reactor vessel 41 is melted, and the melted material is the reactor vessel 41. Is dropped 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 collection device 91 falls on the upper surface portion of the inclined 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 by the inclination of the inclined plate 93.

  That is, the melt that has fallen on the inclined plate 93 in the receiving area 86a moves to the collection area 86b through the communication path 92. Here, the inclined plate 93 in the collection region 86b is inclined downward toward the first direction A away from the pressurized water reactor 12, and downward toward the second direction B that is the width direction thereof. Because of the inclination, the melt on the inclined plate 93 is diffused as a whole on the inclined plate 93 in the collection region 86b. Therefore, the molten material diffusing on the inclined plate 93 is collected in a plurality of spherical concave portions 94 arranged at equal intervals and separated into small volumes. Then, the small volume melt collected in each spherical concave portion 94 of the inclined plate 93 is cooled by removing heat from 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. An inclined plate 93 for diffusing the melt falling from 12 is provided, and a plurality of spherical concave portions 94 are formed in a staggered pattern at predetermined intervals on the inclined plate 93.

  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 and diffused by the inclined plate 93 and flows along the inclined plate 93. Thus, the light is collected in a plurality of spherical concave portions 94 arranged in a staggered manner. Therefore, the melt falling from the pressurized water reactor 12 is collected in each spherical recess 94 to be separated into small volumes, and the melt as the small volumes is cooled at an early stage to improve safety. Can be planned.

  Further, in the melt collecting apparatus of the first embodiment, the melt receiving region 86a located below the pressurized water reactor 12 in the cavity 86, and the melt is diffused and cooled adjacent to the receiving region 86a. The collection area 86b is provided, and the inclined plate 93 is inclined downward in the first direction A that moves from the receiving area 86a to the collection area 86b, and the plurality of spherical concave portions 94 are inclined plates 93 of the collection area 86b. Is formed. Therefore, the melt from the pressurized water reactor 12 is received by the inclined plate 93, diffused by moving from the receiving area 86a to the collecting area 86b, and collected in a plurality of spherical recesses 94 in the collecting area 86b. Is done. Therefore, the melt is separated into small volumes in the collection region 86b located at a position away from the pressurized water reactor 12, and the melt can be cooled early.

  In the melt collecting apparatus according to the first embodiment, the receiving region 86a and the collecting region 86b communicate with each other through a communication passage 92 having a small passage area. Accordingly, the melt from the pressurized water reactor 12 falls to the receiving region 86a and moves to the collection region 86b through the communication path 92, and therefore, an appropriate amount of melt is supplied to the collection region 86b and diffused. , Collected in a plurality of spherical recesses 94. Therefore, the melt can be properly guided to the plurality of spherical concave portions 94, and the melt can be cooled early.

  Further, in the melt collecting apparatus of the first embodiment, the communication path 92 side in the collecting region 86b is widened in the first direction A. Therefore, when the molten material from the pressurized water reactor 12 moves from the receiving region 86a to the collection region 86b through the communication path 92, it spreads in the width direction by the widened portion. Therefore, this melt can be appropriately guided to the plurality of spherical concave portions 94, and the melt can be cooled early.

  In the melt collecting apparatus according to the first embodiment, the inclined plate 93 is inclined downward in the first direction A away from the communication path 92 and intersects the first direction A. It is inclined downward in the direction B. Therefore, the melt from the pressurized water reactor 12 is received by the inclined plate 93, and moves widely from the receiving area 86a to the collecting area 86b and moves in the width direction of the collecting area 86b. Become. Therefore, this melt can be appropriately guided to the plurality of spherical concave portions 94, and the melt can be cooled early.

  Further, in the melt collecting apparatus of the first embodiment, a reactor cooling path 89 and a reactor containment vessel cooling path 90 are provided as cooling water supply apparatuses capable of supplying cooling water to the cavities 86. Accordingly, the melt that has become a small volume collected in the plurality of spherical recesses 94 is efficiently cooled by the cooling water, and the melt can be cooled early.

  In the first embodiment, the collection region 86b is configured such that the passage width is widened from the communication path 92 toward the first direction A. However, the communication path 92 is directed toward the first direction A. You may expand to the same width as the collection area | region 86b. In the first embodiment, the inclined plate 93 is configured to incline downward in the first direction A and incline downward in the second direction B. The degree may not be uniform with respect to the first direction A, and the degree of inclination on the upstream side may be reduced or increased.

  FIG. 7 is a schematic configuration diagram of a melt collecting device applied to a reactor containment vessel according to a second embodiment of the present invention, and FIG. 8 is a schematic plan view illustrating the melt collecting device of the second embodiment. It is. In addition, the same code | symbol is attached | subjected to the member which has the function similar to the Example mentioned above, and detailed description is abbreviate | omitted.

  In the second embodiment, as shown in FIGS. 7 and 8, a cavity 86 capable of supplying cooling water is provided below the pressurized water reactor 12, and the cavity 86 drops 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. 86a and the collection area | region 86b are formed continuously.

  The upper surface of the protective concrete 85a on the steel plate liner 82 is an inclined surface 85b, and the inclined plate 102 constituting the collection device 101 is fixed to the inclined surface 85b of the protective concrete 85a. The inclined plate 102 extends from the receiving area 86a to the collecting area 86b, and the upper surface (inclined surface) is inclined downward in the first direction A from the receiving area 86a toward the collecting area 86b.

  The inclined plate 102 has a plurality of spherical recesses 103 arranged in a staggered pattern at predetermined intervals on the upper surface (inclined surface) in the receiving region 86a and the collection region 86b. The spherical concave portions 103 are arranged adjacent to each other at equal intervals, and are formed in contact with the wall surface of the cavity 86.

  The cavity 86 is provided with a cooling water circulation path 104 for circulating the stored cooling water, and a pump 105 and a heat exchanger 106 are provided in the cooling water circulation path 104. That is, when an accident such as loss of coolant occurs in an emergency, the pump 105 is driven and the cooling water stored in the cavity 86 is circulated through the cooling water circulation path 104, so that it is stored in the cavity 86 by the heat exchanger 106. Cooling water 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 is melted, and the melt breaks the reactor vessel. Drop 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 inclined plate 102 in the receiving region 86 a of the cavity 86. The melt falling on the inclined plate 102 in the receiving area 86a moves to the collection area 86b due to the inclination. At this time, since the melt on the inclined plate 102 diffuses throughout the receiving area 86a and the collection area 86b, it is collected in a plurality of spherical recesses 103 arranged at equal intervals and separated into small volumes. The Then, the small volume melt collected in each spherical recess 103 of the inclined plate 102 is cooled by removing heat from 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. An inclined plate 102 for diffusing the melt falling from 12 is provided, and a plurality of spherical recesses 103 are formed in a staggered pattern at predetermined intervals in all regions of the inclined plate 102.

  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 inclined plate 102 and diffused, and flows along the inclined plate 102. Thus, the light is collected in a plurality of spherical recesses 103 arranged in a staggered manner. For this reason, the melt falling from the pressurized water reactor 12 is collected in each spherical recess 103 to be separated into small volumes, and the melt as this small volume is cooled at an early stage to improve safety. Can be planned.

  FIG. 9 is a schematic configuration diagram of a melt collecting device applied to a nuclear reactor containment vessel according to Embodiment 3 of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the function similar to the Example mentioned above, and detailed description is abbreviate | omitted.

  In Example 3, as shown in FIG. 9, a cavity 86 capable of supplying cooling water is provided below the pressurized water reactor 12, and the melted material dropped from the pressurized water reactor 12 in an emergency. A collecting device 111 is provided for receiving and cooling. The collector 111 receives the melt that has fallen 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 111, 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. 86a and the collection area | region 86b are formed continuously.

  The upper surface of the protective concrete 85a on the steel plate liner 82 is a horizontal surface 85c, and the inclined plate 112 constituting the collection device 111 is disposed above the protective concrete 85a. The inclined plate 112 extends from the receiving area 86a to the collecting area 86b, and the upper surface (inclined surface) is inclined downward in the first direction A from the receiving area 86a toward the collecting area 86b.

  In addition, the inclined plate 112 is formed with a plurality of spherical recesses 113 arranged in a staggered pattern at predetermined intervals on the upper surface (inclined surface) in the receiving region 86a and the collection region 86b. The spherical recesses 113 are arranged adjacent to each other at equal intervals, and are formed in contact with the wall surface of the cavity 86.

  Furthermore, the cavity 86 has a space 114 provided between the protective concrete 85a and the inclined plate 112 by arranging the inclined plate 112 from the receiving region 86a to the collection region 86b. In this case, since the gap is provided between both side portions of the inclined plate 112 and the wall surface of the cavity 86, the space portion 114 communicates with the upper portion of the inclined plate 112, and the cooling supplied to the cavity 86 is performed. Water can be circulated.

  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 melt that has fallen from the pressurized water reactor 12 in the collection device 111 falls to the upper surface of the inclined plate 112 in the receiving region 86 a of the cavity 86. The melt falling on the inclined plate 112 in the receiving area 86a moves to the collection area 86b due to the inclination. At this time, since the melt on the inclined plate 112 diffuses throughout the receiving area 86a and the collection area 86b, it is collected in a plurality of spherical recesses 113 arranged at equal intervals and separated into small volumes. The At this time, the melt of the small volume collected in each spherical recess 113 of the inclined plate 112 is cooled by being removed by the cooling water supplied above the inclined plate 112 or the cooling water circulating in the space 114. Is done.

  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 below the pressurized water reactor 12 in the cavity 86. An inclined plate 112 for diffusing the melt falling from 12 is provided, and a plurality of spherical concave portions 113 are formed in a staggered pattern at predetermined intervals in all regions of the inclined plate 112, and cooling water is supplied below the inclined plate 112. A possible space 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 inclined plate 112 and diffused, and flows along the inclined plate 112. Thus, the light is collected in a plurality of spherical concave portions 113 arranged in a staggered manner. Therefore, the melt falling from the pressurized water reactor 12 is collected in each spherical recess 113 to be separated into small volumes, and the melt as the small volumes is cooled early to improve safety. Can be planned. At this time, the small volume melt collected in each spherical recess 113 of the inclined plate 112 is cooled by the cooling water supplied above the inclined plate 112 or the cooling water circulating in the space 114. The melt can be cooled early.

  FIG. 10 is a schematic configuration diagram of a melt collecting device applied to a nuclear reactor containment vessel according to Embodiment 4 of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the function similar to the Example mentioned above, and detailed description is abbreviate | omitted.

  In the fourth embodiment, as shown in FIG. 10, a cavity 86 capable of supplying cooling water is provided below the pressurized water reactor 12, and the melted material dropped from the pressurized water reactor 12 in an emergency A collecting device 121 is provided for receiving and cooling. The collector 121 receives the melt that has fallen 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 collecting device 121, the upper surface of the protective concrete 85a on the steel plate liner 82 is a horizontal surface 85c, and an inclined plate 122 constituting the collecting device 121 is disposed above the protective concrete 85a. The inclined plate 122 extends from the receiving area 86a to the collecting area 86b, and the upper surface (inclined surface) is inclined downward in the first direction A from the receiving area 86a toward the collecting area 86b. In addition, the inclined plate 122 has a plurality of spherical recesses 123 arranged in a staggered pattern at predetermined intervals on the upper surface (inclined surface).

  Furthermore, in the cavity 86, the inclined plate 122 is disposed from the receiving region 86a to the collection region 86b, so that a space 124 is provided between the protective concrete 85a and the inclined plate 122. The inclined plate 122 has a cooling water passage 125 formed along its longitudinal direction (inclination direction). The cooling water passage 125 is provided with a cooling water circulation path 126 for circulating the cooling water, and the cooling water circulation path 126 is provided with a pump 127 and a heat exchanger 128. That is, in the event of a coolant loss accident or the like in an emergency, the pump 127 is driven, and the cooling water stored in the cavity 86 is circulated to the cooling water passage 125 through the cooling water circulation path 126, so Can be cooled to.

  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 in the collection device 121 falls to the upper surface portion of the inclined plate 122 in the receiving region 86 a of the cavity 86. The melt that has fallen on the inclined plate 122 in the receiving area 86a moves to the collection area 86b due to the inclination. At this time, since the melt on the inclined plate 122 diffuses throughout the receiving area 86a and the collection area 86b, it is collected in a plurality of spherical recesses 123 arranged at equal intervals and separated into small volumes. The At this time, the melt of the small volume collected in each spherical recess 123 of the inclined plate 122 is the cooling water supplied above the inclined plate 122, the cooling water circulating in the space portion 124, and the internal cooling. Heat is removed by cooling water flowing through the water passage 125 and cooled.

  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 in the cavity 86 below the pressurized water reactor 12. An inclined plate 122 for diffusing the melt falling from 12 is provided, and a plurality of spherical concave portions 123 are formed in a staggered pattern at predetermined intervals in all regions of the inclined plate 122, and a cooling water passage 125 is formed inside the inclined plate 122. 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 inclined plate 122 and diffused, and flows along the inclined plate 122. Thus, the light is collected in a plurality of spherical recesses 123 arranged in a staggered manner. For this reason, the melt falling from the pressurized water reactor 12 is collected in each spherical recess 123 to be separated into small volumes, and the melt as the small volumes is cooled early to improve safety. Can be planned. At this time, the melt of the small volume collected in each spherical recess 123 of the inclined plate 122 is cooled by the cooling water flowing through the cooling water passage 125 provided in the inclined plate 122, and the melt Can be cooled early.

  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, in each of the above-described embodiments, the inclined plates 93, 102, 112, 122 are provided above the concrete structure 85. However, an inclined portion may be provided directly on the upper surface of the concrete structure 85, and concrete may be provided. The upper surface of the structure 85 may be an inclined surface, which may be an inclined portion. Furthermore, although the spherical concave portions 94, 103, 113 are provided in a part or all of the inclined plates 93, 102, 112, 122, the positions to be provided are not limited to the embodiment.

  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.

11 Reactor containment vessel 12 Pressurized water reactor 13 Steam generator 85 Concrete structure 85a Protective concrete 85b Inclined surface 86 Cavity 86a Receiving area 86b Collection area 89 Reactor cooling path (cooling water supply device)
90 Reactor containment cooling path (cooling water supply device)
91, 101, 111 Collection device 92 Communication path 93, 102, 112, 122 Inclined plate (inclined surface)
94, 103, 113, 123 Spherical concave portion 114 Space portion 125 Cooling water passage

Claims (7)

A melt collector provided in a cavity below a nuclear reactor,
An inclined surface for diffusing the melt falling from the reactor located below the reactor in the cavity;
A plurality of spherical recesses formed in a staggered pattern at predetermined intervals on the inclined surface;
An apparatus for collecting a melt, comprising:   The cavity has a melt receiving area provided below the reactor, and a collection area for diffusing and cooling the melt adjacent to the receiving area, and the inclined surface extends from the receiving area. 2. The melt collection according to claim 1, wherein the plurality of spherical concave portions are provided at least in the collection region, and are inclined downward in a first direction of transition to the collection region. apparatus.   3. The melt collecting apparatus according to claim 1, wherein the receiving region and the collecting region are communicated with each other through a communication path narrower than a passage area of the receiving region and the collecting region.   The melt collecting apparatus according to claim 3, wherein the communication path or the collection region is widened in the first direction.   The inclined surface is inclined downward in the first direction away from the communication path, and is inclined downward in a second direction intersecting the first direction. Item 5. The melt collecting apparatus according to Item 3 or 4.   6. The melt collecting apparatus according to claim 1, further comprising a cooling water supply device capable of supplying cooling water to the cavity.   The inclined surface is provided with a space portion below, and the cooling water supply device is capable of supplying cooling water to the space portion. Melt collector.

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