JP6320271B2 - Core melt holding device and nuclear facility - Google Patents

Description

  Embodiments of the present invention relate to a core melt holding device that receives and holds a core melt penetrating a reactor pressure vessel when a core melting accident occurs.

  In a nuclear reactor facility, when a primary coolant loss accident or the like occurs and the core cooling continues to be insufficient, the core may melt. In such a case, the emergency core cooling system (ECCS) is usually activated to remove the residual heat of the core, thereby preventing an accident that the core melts (hereinafter referred to as a core melting accident). .

  However, it is assumed that the emergency core cooling device does not operate for some reason, and other devices that can inject cooling water into the core cannot be used. When a core melting accident actually occurs, the hot core melt may melt into the bottom of the reactor pressure vessel (so-called lower mirror) and penetrate the bottom. The core melt that has penetrated the bottom of the reactor pressure vessel may fall into a portion of the containment vessel that faces the bottom of the reactor pressure vessel (hereinafter referred to as a containment vessel floor).

  Such a containment vessel floor is usually mainly composed of concrete. When a high temperature core melt comes into contact with the containment floor and reacts, noncondensable gases such as carbon dioxide and hydrogen are generated and the concrete on the containment floor is melted and eroded. As a result, if the reaction between the concrete on the floor of the containment vessel and the core melt continues, the containment vessel may be damaged due to erosion of the concrete or an increase in pressure in the containment vessel due to the generated incompressible gas.

  For this reason, when the core melt contacts the containment vessel floor, the core melt is cooled so that the temperature of the contact surface is equal to or lower than the erosion temperature of concrete (for example, 1500 K or less). It is desired that the concrete constituting the storage container floor is not in direct contact.

  Therefore, in case the core melt falls from the reactor pressure vessel, the core melt that catches the core melt that falls through the reactor pressure vessel vertically below the reactor pressure vessel in the dry well. Techniques for providing an object holding device (so-called core catcher) have been proposed (see, for example, Patent Documents 1 and 2). Patent Documents 1 and 2 disclose a technique for cooling the core melt holding device and the core melt by guiding the cooling water stored in the pressure suppression pool to the core melt holding device in the event of a core melting accident. Proposed.

Japanese Patent No. 3150451 JP 2005-195595 A

  By the way, in the techniques described in Patent Documents 1 and 2 described above, the cooling water is used to divide the space that is vertically below the reactor pressure vessel and the pressure suppression pool among the dry wells formed in the containment vessel. It communicates with a passage which can be circulated, and the passage is provided with a valve which can block the flow of cooling water. The core melt holding device holding the high temperature core melt by opening this valve and guiding the cooling water stored in the pressure suppression pool to the vertically lower side of the core melt holding device in the dry well. Is cooling.

The above-described valve is generally configured such that the valve body is driven from the closed position to the open position in response to radiant heat from the core melt. Therefore, for example, about 15 minutes from when the core melt holding device receives the core melt melted down through the reactor pressure vessel until the cooling water of the pressure suppression pool is guided to the core melt holding device. Time may be required. In addition, it may take about 10 minutes before the cooling water is filled around the core melt holding device. During this time, the core melt holding device needs to receive and hold the core melt, and among the core melt holding device, in particular, in the portion facing the bottom of the reactor pressure vessel in the vertical direction, Extremely high heat resistance is required. For this reason, in the core melt holding device, the portion facing the bottom of the reactor pressure vessel in the vertical direction is generally a material having a high melting point (for example, about 2500 K to 3000 K) (hereinafter referred to as a high melting point heat-resistant material). It is composed of As the high melting point heat-resistant material, for example, zirconium oxide (ZrO ₂ : hereinafter simply referred to as “zirconia”), tungsten (W), tantalum (Ta), or the like is used.

  However, such a high melting point heat-resistant material may be eroded by a chemical reaction with the core melt until the core melt holding device is cooled by the cooling water. Also, the core melt, which is a high-temperature liquid state ejected in a jet form from the bottom of the reactor pressure vessel, locally collides with the high-melting point heat-resistant material, and erosion due to melting of the high-melting-point heat resistant material (hereinafter simply referred to as “high melting point heat resistant material” So-called jet impingement may occur which causes “melt erosion”).

  For this reason, it is conceivable to make the member composed of the high-melting-point heat-resistant material thicker, etc., but the high-melting-point heat-resistant material is more expensive than a general steel material, and the core melt holding device There is a problem that the cost spent for the increase. It is also conceivable to store cooling water in the lower space where the core melt holding device is installed from the normal operation, but there is a risk of steam explosion when the cooling water contacts the core melt. There is. In a boiling water reactor, a work space for exchanging control rods is required vertically below the reactor pressure vessel, and the space and the space for storing cooling water must be structurally separated. There is.

  Embodiments of the present invention have been made in view of the above circumstances, and are capable of receiving and holding a core melt for at least a predetermined time during a core melting accident while suppressing the amount of high melting point heat-resistant material used. An object is to provide a possible core melt holding device.

In order to achieve the above object, a core melt holding device of an embodiment of the present invention is provided on a vertically lower side of a bottom portion of a reactor pressure vessel in a containment vessel, and on a vertically upper side of the holding plate. A plurality of receiving spaces extending in the vertical direction, a buffer member having a plurality of openings facing the bottom of the reactor pressure vessel on the vertical upper side of the receiving space, and a cooling member disposed in each of the receiving spaces And a heat-dissipating member that extends along the shock-absorbing member vertically below the shock-absorbing member, and in which a cooling liquid is enclosed, and that can dissipate heat received from the shock-absorbing member. It is characterized by.

A nuclear facility according to an embodiment of the present invention includes a containment vessel for storing a reactor pressure vessel, a holding plate provided on a vertical lower side of the bottom of the reactor pressure vessel in the containment vessel, and A plurality of receiving spaces provided on the vertical upper side and extending in the vertical direction, a buffer member having a plurality of openings facing the bottom portion of the reactor pressure vessel on the vertical upper side of the receiving space, and the receiving space are arranged in each of the receiving spaces. A cooling member that extends along the buffer member vertically below the buffer member, and in which a cooling liquid is enclosed, and is capable of radiating heat received from the buffer member; It is characterized by providing.

  According to the embodiment of the present invention, a core melt can be received and held for at least a predetermined time in a core melting accident.

1 is a sectional elevation view of a nuclear facility including a core melt holding device according to a first embodiment. 1 is a sectional elevation view showing a core melt holding device of a first embodiment and its peripheral configuration. It is a perspective view which shows the vicinity of the opening which opposes the bottom part of a reactor pressure vessel among the core melt holding apparatuses of 1st Embodiment, and is a buffer facing a bottom part of a reactor pressure vessel among core melt holding apparatuses. It is a figure which shows the example by which the member is comprised by the several box-shaped member. FIG. 2 is a sectional elevation view showing a peripheral configuration of an opening facing the bottom of the reactor pressure vessel and a receiving space in the core melt holding device of the first embodiment, and a bag-like cooling capsule is arranged as a cooling member FIG. FIG. 5 is a cross-sectional elevation view showing a peripheral configuration of an opening facing the bottom of the reactor pressure vessel and a receiving space in a core melt holding device of a modification of the first embodiment, and a spherical cooling capsule as a cooling member The mode which is arranged is shown. FIG. 5 is a sectional elevational view showing a peripheral configuration of an opening facing the bottom of a reactor pressure vessel and a receiving space in a core melt holding device of a modification of the first embodiment, and a solid coolant is arranged as a cooling member FIG. FIG. 5 is a sectional elevation view showing a peripheral configuration of an opening facing the bottom of the reactor pressure vessel and a receiving space in a core melt holding device of a modification of the first embodiment, and a granular coolant is arranged as a cooling member FIG. It is a perspective view which shows the opening and receiving space which oppose the bottom part of a reactor pressure vessel among the core melt holding apparatuses of 1st Embodiment, and opposes the bottom part of a reactor pressure vessel among core melt holding apparatuses. It is a figure which shows the example by which the buffer member is comprised by the plate-shaped member combined in the grid | lattice form. FIG. 4 is a cross-sectional view of an opening facing a bottom of a reactor pressure vessel and a receiving space in the core melt holding device of the second embodiment, and for cooling with a cooling liquid sealed between adjacent box-shaped members It is a figure which shows the example by which the capsule was arrange | positioned. FIG. 9 is a sectional elevation view showing a peripheral configuration of an opening facing the bottom of a reactor pressure vessel and a receiving space in a core melt holding device of a third embodiment, in which a cooling liquid is enclosed, and the buffer The heat dissipation member that can dissipate the heat received from the member extends along the buffer member.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the embodiments described below, and various modifications can be made without departing from the scope of the invention.

[First Embodiment]
A schematic configuration of a nuclear facility including the core melt holding device of the first embodiment will be described with reference to FIG. FIG. 1 is a sectional elevation view of a nuclear facility including a core melt holding device of the present embodiment.

  In each figure, the upper side of the vertical direction is indicated as “vertical upper side” and indicated by arrow U, and the lower side is indicated as “vertical lower side” and indicated by arrow D. In addition, the horizontal direction is indicated by an arrow H. Further, the side closer to the core in the horizontal direction is referred to as “horizontal inner side”, and the direction opposite to the horizontal inner side is referred to as “horizontal outer side”.

  As shown in FIG. 1, the nuclear facility 1 of the present embodiment has a boiling water reactor (BWR), and specifically accommodates a reactor core 2 and a reactor internal structure (not shown). A reactor pressure vessel 10 and a containment vessel 20 for storing the reactor pressure vessel 10 are provided. In this embodiment, the reactor pressure vessel 10 is made of steel, and the containment vessel 20 is made of reinforced concrete having a steel lining.

  The reactor pressure vessel 10 includes a cylindrical portion 12 that is a cylindrical portion whose axial center extends in the vertical direction, a pressure vessel bottom portion 14 that is a portion that forms a vertically lower side than the cylindrical portion 12, and the cylindrical portion 12. It has the top part 16 which is a part which comprises the more vertically upper side. When the state in which the core 2 is not sufficiently cooled is continued and the core 2 is melted, the pressure vessel bottom 14 is heated to receive a melt of the core, that is, a so-called core melt. In such a core melting accident, the core melt passes through the pressure vessel bottom 14 that has become high temperature and melts downward from the pressure vessel bottom 14.

  The storage container 20 is partitioned into a dry-well 21 and a wet-well 22. In the containment vessel 20, a wet well 22 is provided with a pool (hereinafter referred to as a pressure suppression pool) 23 that condenses steam (coolant) released from the reactor pressure vessel 10 and returns it to water. Note that a portion of the storage container 20 that extends in the horizontal direction vertically below the pressure container bottom 14 is referred to as a “floor” and denoted by reference numeral 24 below.

  The pressure suppression pool 23 stores water as a coolant (hereinafter simply referred to as “cooling water”). The pressure suppression pool 23 suppresses the pressure rise in the dry well 21 by cooling and condensing the steam from the reactor pressure vessel 10. The pressure suppression pool 23 is provided outside the containment vessel 20 in the horizontal direction from the reactor pressure vessel 10.

  Of the wall bodies 25 and 26 that define the wet well 22, a wall body that supports the reactor pressure vessel 10 with respect to the floor portion 24 of the containment vessel 20 (hereinafter referred to as a wall body 26 extending in the vertical direction) , Pedestal) 28 is provided. The pedestal 28 protrudes from the floor portion 24 of the containment vessel 20 and extends vertically upward, and is coupled to the tubular portion 12 to support the reactor pressure vessel 10. The pedestal 28 is mainly made of concrete. In the dry well 21, a space that is horizontally inward from the pedestal 28 and vertically below the pressure vessel bottom 14 is hereinafter referred to as a “lower space” and is denoted by reference numeral 21 c in the drawing.

  Of the space in the containment vessel 20, the core melt that penetrates the pressure vessel bottom 14 is located at the bottom of the lower space 21 c (the space below the containment vessel 20 inside the pedestal 28 on the vertical lower side of the reactor pressure vessel 10). A core melt holding device 30 is provided to receive the core melt. The core melt holding device 30 is disposed vertically below the pressure vessel bottom 14 and faces the pressure vessel bottom 14 in the vertical direction. The core melt holding device 30 is configured to receive the core melt that has penetrated through the pressure vessel bottom 14 and dropped vertically downward from the pressure vessel bottom 14 in the event of a core melting accident.

  In the nuclear facility 1 of the present embodiment, the pressure suppression pool 23 and the lower space 21c are communicated with each other in the containment vessel 20 so that the cooling water stored in the pressure suppression pool 23 at the time of the core melting accident is stored. A passage (not shown) leading to the lower space 21c and a valve 7 provided in the passage and blocking communication between the pressure suppression pool 23 and the lower space 21c during normal operation are provided. The valve 7 is configured to open by receiving radiant heat from the core melt. When the valve 7 is opened in the core melting accident, the cooling water stored in the pressure suppression pool is guided to the lower space 21c, and the periphery of the core melt holding device 30 in the lower space 21c is Filled with cooling water. In this way, the core melt holding device 30 can be cooled.

  Next, a detailed configuration of the core melt holding device 30 of the present embodiment will be described with reference to FIGS. FIG. 2 is a sectional elevation view showing the core melt holding device of the present embodiment and its peripheral configuration. FIG. 3 is a perspective view showing the vicinity of the opening facing the bottom of the reactor pressure vessel in the core melt holding device of the present embodiment, and facing the bottom of the reactor pressure vessel in the core melt holding device. It is a figure which shows the example in which the buffer member to be comprised by the some box-shaped member. FIG. 4 is a sectional elevation view showing the peripheral configuration of the opening and receiving space facing the bottom of the reactor pressure vessel in the core melt holding device of the present embodiment, and a bag-like cooling capsule as a cooling member The mode which is arranged is shown. In FIG. 2, the axis of the cylindrical portion 12 of the reactor pressure vessel 10 is indicated by a one-dot chain line A, and hereinafter referred to as “reactor axis”.

  FIG. 5 is a sectional elevation view showing the peripheral configuration of the opening and the receiving space facing the bottom of the reactor pressure vessel in the core melt holding device of the modification of the present embodiment, and a spherical shape as a cooling member The mode which the capsule for cooling of this is arrange | positioned is shown. FIG. 6 is a cross-sectional elevation view showing the peripheral configuration of the opening facing the bottom of the reactor pressure vessel and the receiving space in the core melt holding device of the modification of the present embodiment, and a solid coolant as a cooling member The mode which is arranged is shown. FIG. 7 is a sectional elevation view showing the peripheral configuration of the opening and receiving space facing the bottom of the reactor pressure vessel in the core melt holding device of the modification of the present embodiment, and a granular coolant as a cooling member The mode which is arranged is shown. FIG. 8 is a perspective view showing an opening and a receiving space facing the bottom of the reactor pressure vessel in the core melt holding device of the present embodiment, and the bottom of the reactor pressure vessel in the core melt holding device. It is a figure which shows the example by which the opposing buffer member is comprised by the plate-shaped member combined in the grid | lattice form.

  As shown in FIGS. 1 and 2, the core melt holding device 30 is installed at the bottom of the space inside the pedestal 28 on the vertical lower side of the reactor pressure vessel 10 in the containment vessel 20 with the vertical upper side opened. As a result, the core melt that has fallen vertically downward from the pressure vessel bottom 14 is received.

  The core melt holding device 30 includes a mortar-shaped holding plate 40 that includes a high melting point heat-resistant material and receives the core melt, and a lower plate 44 that is provided below the holding plate 40 and is in contact with cooling water. A cooling water passage 48 through which cooling water can be circulated provided on the lower side of the lower plate 44, and a buffer member 31 installed on the upper side of the holding plate 40 so as to face the pressure vessel bottom 14. Yes. That is, in the core melt holding device 30 of the present embodiment, the core melt that has passed through the pressure vessel bottom portion 14 and has melted down vertically is first received by the buffer member 31 on the vertical upper side of the holding plate 40. It is configured to accept. The detailed configuration of the buffer member 31 will be described later.

  The holding plate 40 has a plate shape and includes a high melting point heat-resistant material such as zirconia. The lower plate 44 has a plate shape, is provided along the holding plate 40, and is made of a relatively high anticorrosion material such as stainless steel.

  A cooling water passage 48 formed under the lower plate 44 and through which cooling water can flow is used for cooling water supplied from the pressure suppression pool 23 (see FIG. 1) to the lower space 21c in the event of a core melting accident. It is a passage that circulates. Each of the holding plate 40 and the lower plate 44 has a constant height within a predetermined range from the reactor core (indicated by a one-dot chain line A in the figure) that is the central portion, but outside the predetermined range, It has a mortar-like shape (reverse frustoconical shape) toward the center so that its height increases toward the outside in the horizontal direction (located vertically above). The cooling water passage 48 increases in height toward the outer side in the horizontal direction along the lower plate 44 outside the predetermined range from the center portion where the height of the lower plate 44 is constant (vertical upper side). Is located).

  When the core melt holding device 30 receives the core melt at the buffer member 31, the core melt holding device 30 cools the cooling water passage 48 from the buffer member 31 via the holding plate 40 and the lower plate 44. It can be transmitted to water. The cooling water supplied to the lower space 21c at the time of the core melting accident receives heat from the lower plate 44 in the cooling water passage 48, the cooling water temperature rises or becomes water vapor, and the cooling water passage 48 is horizontally moved by natural convection. Flows from the inside to the outside.

  On the other hand, the buffer member 31 extends vertically above the holding plate 40 and has a plurality of spaces 33 (hereinafter referred to as receiving spaces) in which the core melt can be received. A plurality of openings 32 facing the pressure vessel bottom 14 are arranged in the horizontal direction vertically above the space 33. In the present embodiment, the receiving space 33 is configured as a rectangular parallelepiped space. The receiving space 33 receives the core melt melted through the pressure vessel bottom 14 in the event of a core melting accident. The openings 32 respectively provided on the upper vertical side of the receiving space 33 face the lower side of the pressure vessel bottom 14 in the vertical direction. A plurality of openings 32 are arranged in the horizontal direction corresponding to each of the receiving spaces 33.

  As shown in FIGS. 3 and 4, the buffer member 31 is configured by arranging a large number of bottomed box-like members (hereinafter referred to as box-like members) 50 without gaps in the horizontal direction. The bottom wall 34 is provided on the holding plate 40 and faces the opening 32 in the vertical direction, and the walls 51 and 52 are connected to the bottom wall 34 and extend vertically upward with respect to the holding plate 40. Specifically, the box-shaped member 50 is, for example, a flat wall body (hereinafter referred to as a first wall) extending in a predetermined direction (hereinafter referred to as a first horizontal direction) indicated by an arrow H1 in the drawing in the horizontal direction and a vertical direction. 51), a direction orthogonal to the first horizontal direction (hereinafter referred to as the second horizontal direction and indicated by an arrow H2 in the figure) and a flat wall body (hereinafter referred to as the second wall body) extending in the vertical direction. ) 52.

  By arranging the plurality of box-shaped members 50 without gaps to form the buffer member 31, a plurality of first wall bodies 51 are arranged at predetermined intervals in the second horizontal direction, and the second wall bodies 52 are A plurality are arranged at predetermined intervals in the first horizontal direction. In the buffer member 31 configured as described above, the plurality of first wall bodies 51 and the plurality of second wall bodies 52 extend so as to cross in a lattice shape in a cross section perpendicular to the vertical direction. In other words, when viewed from the pressure vessel bottom 14 side, the first wall body 51 and the second wall body 52 extend so as to intersect in a lattice pattern.

  In addition, the box-shaped member 50 which is the buffer member 31 of this embodiment is comprised with comparatively cheap metals, such as steel. It is also preferable to use a relatively inexpensive ceramic such as an aluminum oxide sintered body. For example, a film of a material having a relatively high melting point such as tungsten or tantalum is formed on the surface of the box-shaped member 50 on the surface of the first wall body 51 or the second wall body 52 by vapor deposition or thermal spraying. It may be good.

  In the present embodiment, the receiving space 33 (see FIG. 2) of the buffer member 31 includes two second wall bodies 52 that are provided to face each other at a predetermined interval in the first horizontal direction, and in the second horizontal direction. It is defined by being surrounded by two first wall bodies 51 provided to face each other at a predetermined interval, and a bottom (not shown) extending in the first horizontal direction and the second horizontal direction. That is, the opening 32 (see FIG. 2) on the upper vertical side of the receiving space 33 is surrounded by the vertical upper edge 51 a of the first wall body 51 and the vertical upper edge 52 a of the second wall body 52. Yes.

  As shown in FIG. 4, the buffer member 31 configured as described above has a receiving space 33 extending vertically downward from the opening 32, and a bottom wall body 34 that faces the opening 32 in the vertical direction is formed. Has been. In the present embodiment, the bottom wall body 34 is a bottom of the box-shaped member 50 that is the buffer member 31 described above, and is a portion that is installed on the holding plate 40. The bottom wall 34 receives the core melt flowing into the receiving space from the opening 32. A plurality of receiving spaces 33 are arranged in the horizontal direction.

  Each receiving space 33 is provided with a member for cooling the core melt flowing from the opening 32 (hereinafter referred to as a cooling member). As shown in FIG. 4, in the present embodiment, in the receiving space 33, a capsule (hereinafter referred to as a cooling capsule) in which a cooling liquid (hereinafter referred to as “cooling liquid”) 62 is sealed as a cooling member. 60) is arranged.

  The cooling capsule 60 has a bag shape, and is configured such that a cooling liquid 62 such as water is enclosed in a capsule body 61 made of a synthetic resin. The cooling capsule 60 is disposed on the bottom wall 34 defining the receiving space 33 in the buffer member 31, and is laid down so as to cover the bottom wall 34.

  In addition, although the cooling capsule 60 of the present embodiment is assumed to have a bag shape, the form of the cooling capsule is not limited to this. For example, as in the modification shown in FIG. 5, the cooling capsule 60 </ b> B may have a spherical shape, and a large number (multiple) may be spread over the bottom wall 34.

  As shown in FIG. 1, the nuclear facility 1 configured as described above has a core melt when a core melt accident occurs and the core melt melted in the core 2 falls through the pressure vessel bottom 14. The buffer member 31 of the holding device 30 receives the core melt. The core melt that has fallen from the pressure vessel bottom 14 flows into the receiving space 33 from the opening 32 of the buffer member 31. In the cooling capsule 60, the capsule main body 61 is broken by heat, and the cooling liquid 62 sealed inside evaporates in contact with the core melt. The cooling capsule 60 uses the latent heat of vaporization of the cooling liquid 62 to cool the core melt flowing into the receiving space 33.

  As a result, a part of the core melt in the receiving space 33 is solidified due to a decrease in temperature and becomes crusted. Thereby, it can suppress that the core melt which is high temperature and is in the liquid state contacts the bottom part wall body 34 and the holding plate 40 of the buffer member 31 directly. Since the core melt crusted on the bottom wall 34 has a higher thermal resistance than the liquid core melt, the liquid (that is, high-temperature) core melt that is vertically above the receiving space 33 It is possible to suppress heat from being transmitted to the holding plate 40.

  The core melt flowing into the receiving space 33 from the opening 32 of the buffer member 31 accumulates in the receiving space 33. As long as the core melt does not exceed the vertical upper side of the first wall body 51 and the second wall body 52 constituting the box-shaped member 50 or the first wall body 51 and the second wall body 52 are destroyed by melt erosion, Does not spread in the direction. Accordingly, the jet impingement described above prevents the bottom wall body 34 of the buffer member 31 and the holding plate 40 adjacent to the bottom wall body 34 from being melted and eroded.

  The core melt holding device 30 can delay the melt erosion of the bottom wall body 34 and the holding plate 40 of the buffer member 31 facing the pressure vessel bottom 14 during a core melting accident by a predetermined time. When a predetermined time has elapsed, the lower space 21c is filled with cooling water from the pressure suppression pool 23. With this cooling water, the core melt holding device 30 and the core melt held by the core melt holding device 30 are cooled.

  As described above, the core melt holding device 30 according to the present embodiment receives and holds the core melt penetrating the pressure vessel bottom 14 which is the bottom of the reactor pressure vessel. The buffer member 31 facing the pressure vessel bottom portion 14 of the core melt holding device 30 is provided with an opening 32 facing the pressure vessel bottom portion 14 and extends in the vertical direction on the vertical upper side of the holding plate 40. A plurality of receiving spaces 33 capable of receiving the core melt flowing in from 32 are formed. Each receiving space 33 has a cooling capsule 60 as a cooling member capable of cooling the core melt flowing into the receiving space 33. Is arranged. By cooling the core melt flowing into the receiving space 33 from the opening 32 by the cooling member, solidification (crusting) of the core melt in the receiving space 33 is promoted and around the core melt holding device 30. Until the cooling water is supplied, the core melt can be received and held.

  In the present embodiment, the cooling member disposed in the receiving space 33 is the bag-like cooling capsule 60 in which a cooling liquid such as water is enclosed. However, the cooling member according to the present invention is not limited thereto. The member is not limited to this embodiment.

  For example, as in the modification shown in FIG. 6, a cooling material (hereinafter, referred to as a solid cooling material) 70 made of solid as a cooling member may be arranged in the receiving space 33. The solid coolant 70 can be made of ceramics obtained by sintering a metal oxide such as aluminum oxide (alumina), for example. In this modification, the solid coolant 70 is disposed on the bottom wall 34 facing the receiving space 33 so as to cover the bottom wall 34. The solid coolant 70 can be made of a metal having a lower melting point than that of the core melt.

  Further, as in the modification shown in FIG. 7, as a cooling member, a large number of coolants 73 (hereinafter referred to as granular coolants) composed of granular solids are arranged in the receiving space 33. Also good. As the granular coolant 73, for example, a metal sphere can be used. In this modification, a large number of granular coolants 73 are arranged on the bottom wall 34 facing the receiving space 33 so as to cover the bottom wall 34. According to this aspect, the contact area with the core melt can be increased. The granular coolant 73 may be disposed in the receiving space 33 in a mixed manner with the cooling capsules 60 and 60B described above.

  Further, in the present embodiment, the buffer member 31 is configured such that a large number of box-shaped members 50 having a bottomed box shape are arranged without gaps in the horizontal direction. The aspect of the member is not limited to this. The buffer member according to the present invention is provided with a receiving space provided vertically above the holding plate 40 and extending in the vertical direction to receive the core melt, and an opening facing the bottom of the pressure vessel bottom 14 on the vertical upper side of the receiving space. If it is what is.

  For example, like the buffer member 31C of the modification shown in FIG. 8, a plate-like member (hereinafter referred to as a first vertical plate) extending in a predetermined first horizontal direction (indicated by an arrow H1 in the drawing) and a vertical direction in the horizontal direction. And a flat plate member (hereinafter referred to as a second vertical plate) 56 extending in the second horizontal direction (indicated by an arrow H2) orthogonal to the first horizontal direction and extending in the vertical direction. Is preferred. In the present modification, the first vertical plate 55 and the second vertical plate 56 are formed with notches (not shown) for combining them. The buffer member 31C is formed by combining the plurality of first vertical plates 55 and the plurality of second vertical plates 56 so as to form a lattice shape in a cross section perpendicular to the vertical direction (that is, viewed from the pressure vessel bottom 14). To do.

  31 C of buffer members comprised in this way are the 1st wall bodies 51C arranged in the 2nd horizontal direction at predetermined intervals as a wall body which demarcates receiving space 33C, and the predetermined 1st horizontal direction And a plurality of second wall bodies 52C arranged at intervals. The receiving space 33C is provided opposite to each other with two second walls 52C provided to face each other with a predetermined interval in the first horizontal direction, and to the two horizontal walls 52C with a predetermined interval in the second horizontal direction. The two first walls 51C are surrounded and defined. Also according to this aspect, the buffer member is formed with a plurality of openings facing the pressure vessel bottom portion 14 on the vertically lower side and a receiving space formed in the vertical upper side of the holding plate 40 in the vertical direction to receive the core melt from the openings. Can be realized.

[Second Embodiment]
A core melt holding device according to a second embodiment will be described with reference to FIG. FIG. 9 is a cross-sectional view of an opening facing the bottom of the reactor pressure vessel and the vicinity of the receiving space in the core melt holding device of the present embodiment, in which a cooling liquid is sealed between adjacent box-shaped members. It is a figure which shows the example by which the capsule for cooling was arrange | positioned.

  The core melt holding device of this embodiment is different from that of the first embodiment in that a cooling member is disposed between adjacent box-like members. In addition, about the structure substantially common to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the core melt holding device of the present embodiment, the buffer member 31E is configured by arranging a plurality of box-like members 50 as in the first embodiment (see FIGS. 3 and 4). As shown in FIG. 9, between the adjacent box-shaped members 50, specifically, between the first wall body 51 of one box-shaped member 50 and the first wall body 51 of the other box-shaped member. Is formed with a gap 36 extending in the vertical direction. Similarly, a gap 36 extending in the vertical direction is formed between the second wall body 52 of one box-shaped member 50 and the second wall body 52 of the other box-shaped member 50.

  In these gaps 36, cooling members for cooling the core melt flowing into the receiving space 33 are disposed. In the present embodiment, as a cooling member, a cooling capsule 60E in which a cooling liquid 62 is enclosed is inserted into the gap 36 and provided. In the cooling capsule 60E, a cooling liquid 62 such as water is sealed in a capsule body 61 made of synthetic resin. The cooling capsule 60 </ b> E is inserted into the gap 36 and extends in the vertical direction along the wall body 51 (52) of the box-shaped member 50.

  In addition, a lid 38 is provided on the wall 51 (52) of the box-shaped member 50 to close the gap 36 in which the cooling capsule 60E is inserted. The lid 38 is made of a highly heat-resistant member. By closing the gap 36 with the lid 38, the core melt that has dropped through the pressure vessel bottom 14 (see FIG. 1) The cooling capsule 60E is prevented from being broken by entering the inside 36.

  In the core melt holding device in which the buffer member 31E is configured in this way, when the core melt flows into the receiving space 33 and accumulates, the wall body 51 of the box-shaped member 50 is caused by the core melt in the receiving space 33. (52) can be prevented from being melted and eroded, and the timing at which the core melt diffuses in the horizontal direction can be delayed.

  In the present embodiment, the cooling member disposed in the receiving space 33 is the bag-like cooling capsule 60E in which a cooling liquid such as water is enclosed. However, the cooling member according to the present invention is not limited thereto. The member is not limited to this embodiment. As the cooling member, the above-described solid coolant 70 (see FIG. 6), a large number of granular coolants 73 (see FIG. 7), and the like may be disposed in the gap 36.

[Third Embodiment]
A core melt holding device according to a third embodiment will be described with reference to FIG. FIG. 10 is a sectional elevation view showing the peripheral configuration of the opening and receiving space facing the bottom of the reactor pressure vessel in the core melt holding device of the present embodiment, in which a cooling liquid is enclosed, The heat dissipation member that can dissipate the heat received from the buffer member extends along the buffer member.

  In the core melt holding device of the present embodiment, a cooling liquid is enclosed in the vertical lower side of the buffer member in which the receiving space is formed, and a heat radiating pipe capable of radiating the heat received from the buffer member is disposed. This is different from the first embodiment. In addition, about the structure substantially common to 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the core melt holding device 30G of the present embodiment, the buffer member 31 is configured by arranging a plurality of box-shaped members 50 with no gaps as in the first embodiment (see FIGS. 3 and 4). . As shown in FIG. 10, on the vertical lower side of the bottom wall 34 of the buffer member 31, as a member for radiating the heat received from the buffer member 31 (hereinafter referred to as a heat radiating member), a coolant is provided inside. A substantially tubular member (hereinafter referred to as a heat radiating pipe) 80 is provided. For example, water can be used as the coolant.

  The heat radiating pipe 80 is a metal pipe whose both ends are closed, and a coolant such as water is sealed therein. The heat radiating pipe 80 is provided between the bottom wall 34 of the buffer member 31 and the holding plate 40, and extends along the bottom wall 34 and the holding plate 40. Note that the direction in which the heat radiating pipe 80 extends is particularly indicated as “pipe extending direction” and is indicated by an arrow H3 in the drawing. In the present embodiment, the pipe extension direction substantially coincides with the horizontal direction. In the present embodiment, a plurality of heat radiating pipes 80 are arranged in a direction orthogonal to the pipe extending direction in the horizontal direction, and a plurality of heat radiating pipes 80 are arranged to face the bottom wall 34 of the buffer member 31.

  As shown in FIG. 10, in the event of a core melting accident, the core melt 3 flows into a specific receiving space 33 among the plurality of receiving spaces 33 formed in the buffer member 31, and for each receiving space 33. The amount of core melt deposits is different. The bottom wall 34 on the vertically lower side of the receiving space 33 in which the amount of core melt 3 deposited is particularly high is particularly high. In the heat radiating pipe 80, the heat from the bottom wall 34 is received, and a temperature difference is generated in the cooling liquid sealed inside. Due to the temperature difference, natural convection (so-called thermal siphon phenomenon) occurs in the cooling liquid in the heat radiating pipe 80, as indicated by broken line arrows F1 and F2 in FIG.

  Thereby, the heat dissipation of the wall body which demarcates receiving space 33 with much deposition amount of core melt 3 among buffer members 31 can be promoted. While suppressing that the buffer member 31 is melted and destroyed by heat, the temperature of the core melt 3 received by the buffer member 31 can be lowered.

  In the present embodiment, the heat radiating pipe 80 extends in the horizontal direction along the bottom wall 34 of the buffer member 31, but the heat radiating member according to the present invention is limited to this mode. It is not a thing. The heat dissipating member only needs to extend along the buffer member 31 in which the cooling liquid is sealed and the core melt is received. The heat radiating member is not limited to a tubular one as long as the cooling liquid is enclosed therein, and can be realized using various shapes of members.

[Other Embodiments]
In the core melt holding device of each of the embodiments described above, a plurality of buffer members are formed, and the receiving space 33 for receiving the core melt at the time of a core melting accident has a rectangular parallelepiped shape. The receiving space and the buffer member are not limited to this form. A plurality of receiving spaces formed in the buffer member may be arranged so as to face the bottom of the reactor pressure vessel. For example, the receiving space may have a cylindrical shape or a polygonal column shape.

  Although several embodiments of the present invention have been described, these embodiments have been presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1 Nuclear Facility 2 Core 3 Core Melt 7 Valve 10 Reactor Pressure Vessel 12 Tubular Part 14 Pressure Vessel Bottom (Bottom)
20 containment vessel 21 dry well 21c lower space 22 wet well 23 pressure suppression pool 24 floor 25, 26 wall 28 pedestal 30, 30G core melt holding device 31, 31C, 31E buffer member 32 opening 33, 33C receiving space 34 Bottom wall body 36 Gap 38 Lid 40 Holding plate 44 Lower plate 48 Cooling water passage 50 Box-shaped member 51, 51C First wall body 52, 52C Second wall body 55 First vertical plate 56 Second vertical plate 60, 60B, 60E Capsule 61 for cooling Capsule body 62 Cooling liquid 70 Solid coolant 73 Granular coolant (solid coolant)
80 Heat dissipation pipe

Claims (4)

A holding plate provided vertically below the bottom of the reactor pressure vessel in the containment vessel;
A buffer member provided on the vertical upper side of the holding plate, and having a plurality of receiving spaces extending in the vertical direction and a plurality of openings facing the bottom of the reactor pressure vessel on the vertical upper side of the receiving space;
A cooling member disposed in each of the receiving spaces;
A heat-dissipating member that extends along the shock-absorbing member vertically below the shock-absorbing member, and in which a cooling liquid is enclosed, and that can dissipate heat received from the shock-absorbing member;
A core melt holding device comprising: The core melt holding device according to claim 1, wherein the cooling member includes a cooling capsule in which a cooling liquid is sealed. The cooling member includes a solid coolant composed of a solid,
3. The core melt holding device according to claim 1, wherein the solid coolant is disposed so as to cover a bottom wall that is a wall facing the opening in a vertical direction.   A containment vessel for storing the reactor pressure vessel;
  A holding plate provided vertically below the bottom of the reactor pressure vessel in the containment vessel;
  A buffer member provided on the vertical upper side of the holding plate, and having a plurality of receiving spaces extending in the vertical direction and a plurality of openings facing the bottom of the reactor pressure vessel on the vertical upper side of the receiving space;
  A cooling member disposed in each of the receiving spaces;
  A heat-dissipating member that extends along the shock-absorbing member vertically below the shock-absorbing member and encloses a cooling liquid therein, and that can dissipate heat received from the shock-absorbing member
A nuclear facility characterized by comprising:

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