JP2017062158A - Reactor core molten material holding device and nuclear reactor containment vessel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reactor core molten material holding device and a nuclear reactor containment vessel which are capable of much more stably cooling and holding reactor core molten materials.SOLUTION: A reactor core molten material holding device 15A, which is provided in a pedestal 12, and cools reactor core molten materials M resulting from melting of a reactor core 13 in a nuclear reactor pressure vessel 14 while retaining them on a holding surface 32, includes: a cooling passage 35 through which a coolant 25 passes so as to cool the reactor core molten materials M; first risers 34A, connected to a supply side of the coolant 25, of the cooling passage 35; and second risers 34B, connected to a discharge side of the coolant 25, of the cooling passage 35. The first risers 34A and the second risers 34B are arranged circumferentially along an inner peripheral surface of a pedestal sidewall 17 so that positions in a circumferential direction of the first risers 34A are different from those of the second risers 34B.SELECTED DRAWING: Figure 2

Description

  Embodiments described herein relate generally to a core melt holding device and a reactor containment vessel.

  In a water-cooled nuclear reactor, if cooling water is lost due to the stoppage of water supply to the reactor pressure vessel or the breakage of piping connected to the reactor pressure vessel, the water level in the reactor pressure vessel decreases and the reactor core Exposure may result in inadequate cooling. Assuming such a case, when the water level in the reactor pressure vessel drops, the reactor is automatically shut down, and the core is submerged by injecting coolant with an emergency core cooling system (ECCS). To prevent accidents in the core melting.

  However, although there is an extremely low probability, it may be assumed that the emergency core cooling device does not operate and water injection devices for other cores cannot be used. In such a case, the core is exposed due to a drop in the water level in the reactor pressure vessel and sufficient cooling is not performed, and the fuel rod temperature rises due to decay heat that continues to occur even after the reactor shuts down. A situation that leads to melting of the core is considered. If this happens, the hot core melt will melt into the lower part of the reactor pressure vessel, melt and penetrate the bottom of the reactor pressure vessel, and fall to the floor of the reactor containment vessel. become.

  The core melt heats the concrete floor of the containment vessel and reacts with the concrete when the contact surface becomes hot, generating a large amount of non-condensable gases such as carbon dioxide and hydrogen. Melt and erode. The generated non-condensable gas increases the pressure in the containment vessel and may damage the containment vessel. Moreover, there is a possibility that the reactor containment boundary may be damaged by melting and erosion of concrete, and the structural strength of the reactor containment may be reduced. When the reaction between the core melt and concrete continues and the reactor containment vessel is damaged, radioactive materials in the reactor containment vessel may be released to the external environment.

  In order to suppress the reaction between the core melt and concrete, the temperature of the contact surface of the concrete in contact with the core melt is cooled to below the erosion temperature (1500 K or less for general concrete), or the core melt and concrete are cooled. It is necessary to avoid direct contact with. For this reason, various countermeasures have been proposed in case the core melt falls.

  As a countermeasure against such a fall of the core melt, for example, a coolant that receives the core melt with a heat-resistant material provided on the surface of the structure that holds the dropped core melt and uses a coolant that circulates inside the structure is used. There has been proposed a core melt holding device (core catcher) for cooling the core melt from the bottom. In this conventional core melt holding device, the coolant in the pedestal is supplied from the outside of the riser into the cooling flow path in the structure, and the core melt received by the heat-resistant material is cooled from the bottom, and the core melt This suppresses thermal erosion of the heat-resistant material due to (see Patent Document 1).

  As a result, only the cooling water poured onto the top surface of the core melt that has fallen into the core melt holding device does not sufficiently remove heat from the bottom of the core melt, and the temperature of the bottom of the core melt remains high due to decay heat. Even if maintained, the core melt is also cooled from the bottom to prevent erosion of the reactor containment on the concrete floor.

JP 2014-81212 A

  However, in the conventional core melt holding device, since a gap for supplying the coolant into the cooling flow path in the structure is formed outside the riser, there is sufficient space for holding the core melt in the structure. There is a possibility that the bottom of the core melt cannot be stably cooled while holding the core melt.

  The need for such core melt retention measures is increasing both in Japan and overseas from the viewpoint of ensuring higher safety. Not only newly constructed reactors but also already constructed reactors (existing reactors) The same applies to. In particular, the lower structure of the reactor containment vessel of the existing reactor is often designed not to have a space for installing the above-described core melt holding device. It becomes difficult to apply to existing furnaces due to restrictions on the installation method. Furthermore, the riser is particularly limited in installation space in order to avoid interference with equipment arranged in the containment vessel. However, it is not preferable to cut the pedestal to secure a space for installing the core melt holding device from the viewpoint of maintaining the strength of the containment vessel.

  A core melt that can cool and hold the core melt in a stable manner in order to ensure higher safety and to further improve the measures to hold the core melt in the future. A holding device is desired.

  Therefore, embodiments of the present invention have been made in view of the above circumstances, and provide a core melt holding device and a reactor containment vessel that can cool and hold a core melt even more stably. The purpose is to do.

  A core melt holding device according to an embodiment is provided in a pedestal surrounded by a pedestal side wall and a pedestal bed, and holds a core melt generated by melting a core in a reactor pressure vessel on a holding surface. A core melt holding device for cooling, a cooling passage through which a coolant for cooling the core melt passes, a first riser connected to the coolant supply side of the cooling passage, A second riser connected to the coolant discharge side of the cooling passage, and a plurality of the first risers and the second risers along the inner peripheral surface of the pedestal side wall, The first riser and the second riser are arranged circumferentially so that the positions in the circumferential direction are different.

  A reactor containment vessel according to another embodiment comprises the above-described core melt holding device disposed on the pedestal bed below the reactor pressure vessel.

  According to the present invention, the core melt can be cooled and held even more stably.

It is the schematic explaining the reactor containment vessel to which the core melt holding device concerning a 1st embodiment was applied. It is the schematic which shows the structure of the core melt holding | maintenance apparatus by 1st Embodiment. It is a perspective view explaining the structure of a core melt holding | maintenance apparatus. It is a top view of a core melt holding device. It is a perspective view explaining a part of structure of a core melt holding | maintenance apparatus. It is the figure seen from the AA direction of FIG. It is a figure which shows an example of a structure of a riser. It is a figure which shows an example of the other structure of a riser. It is a figure which shows an example of the other structure of a riser. It is the figure seen from the vertical-axis direction of FIG. It is a top view of an example of other composition of a core melt maintenance block. It is the schematic which shows the structure of the core melt holding | maintenance apparatus by 2nd Embodiment. It is a figure which shows the state which fixed the riser. It is the schematic which shows the structure of the core melt holding | maintenance apparatus by 3rd Embodiment. It is a perspective view explaining a part of structure of a core melt holding | maintenance apparatus. It is the schematic which shows the structure of the core melt holding | maintenance apparatus by 4th Embodiment. It is a figure which shows the other structure of a core melt holding | maintenance apparatus. It is the schematic which shows the structure of the core melt holding | maintenance apparatus by 5th Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail.

(First embodiment)
A core melt holding device according to a first embodiment will be described with reference to the drawings. In the following description, the reactor pressure vessel direction of the core melt holding device may be referred to as “up” or “upper”, and the pedestal bed direction of the core melt holding device may be referred to as “down” or “down”.

  FIG. 1 is a schematic diagram illustrating a reactor containment vessel to which a core melt holding device according to the present embodiment is applied, and FIG. 2 is a schematic diagram illustrating a configuration of the core melt holding device according to the present embodiment. 3 is a perspective view illustrating the configuration of the core melt holding device, FIG. 4 is a plan view of the core melt holding device, and FIG. 5 is a part of the configuration of the core melt holding device. FIG. 6 is a view as seen from the AA direction in FIG. 5. As shown in FIG. 1, a nuclear reactor facility 10 includes a reactor pressure vessel (reactor vessel) in which a cylindrical pedestal 12 whose axis is a vertical direction and a core 13 are housed in a reactor containment vessel 11. 14 and a core melt holding device 15 </ b> A provided in the pedestal 12.

  The pedestal 12 has a circular pedestal floor 16 and a cylindrical pedestal side wall 17 extending upward from the pedestal floor 16. A space surrounded by the pedestal floor 16 and the pedestal side wall 17 below the reactor pressure vessel 14 is referred to as a lower dry well. The reactor pressure vessel 14 is provided above the lower dry well. The reactor pressure vessel 14 is supported on the pedestal side wall 17. The support structure for the reactor pressure vessel 14 is not shown.

  In the reactor containment vessel 11, suppression pool water 18 is stored around the outside of the pedestal 12. When the water in the reactor pressure vessel 14 decreases, an emergency core cooling device (ECCS) (not shown) guides the suppression pool water 18 into the reactor pressure vessel 14 as a coolant to prevent a core melting accident.

  The core melt holding device 15 </ b> A is installed on the pedestal floor 16 below the reactor pressure vessel 14. If a core melting accident occurs, the core melt M may melt the bottom of the reactor pressure vessel 14 and fall to the concrete pedestal floor 16 below the reactor pressure vessel 14. Assuming such a case, the core melt holding device 15A receives and holds the core melt M below the reactor pressure vessel 14 and prevents leakage of radioactive materials from the reactor containment vessel 11 to the outside. Is to do.

  A core melt cooling device 21 is installed outside the reactor containment vessel 11 in order to cool the core melt M held in the core melt holding device 15A in the event of a core melting accident. The core melt cooling device 21 has a coolant storage pool 22, a coolant pipe 23, and a coolant introduction valve 24. The coolant storage pool 22 is a pool for storing in advance a coolant (water) 25 for cooling the core melt M in the event of a core melt accident, and is disposed at a position higher than the core melt holding device 15A. ing. Although the coolant storage pool 22 is installed outside the reactor containment vessel 11, it may be installed inside. The coolant pipe 23 connects the coolant storage pool 22 and the lower dry well, and is arranged so that the coolant 25 can be introduced from the coolant storage pool 22 to the core melt holding device 15A. An introduction valve 24 is arranged. The coolant introduction valve 24 is driven to open and close by a valve drive mechanism. The coolant introduction valve 24 is closed when the nuclear reactor is in normal operation, and is configured to open when the core melt holding device 15A needs to be cooled in the event of a core melting accident. At the time of the core melting accident, the water in the reactor pressure vessel 14 and the coolant 25 injected from the core melt cooling device 21 are supplied to the space below the reactor pressure vessel 14 in the reactor containment vessel 11. The core melt holding device 15A is submerged by the coolant 25.

  As shown in FIGS. 2 to 6, the core melt holding device 15 </ b> A includes a heat resistant material (heat resistant part) 31, a holding part 33 having a holding surface 32 for holding the core melt M, and a riser 34.

  The refractory material 31 is maintained after the fall of the core melt M until the circulation of the coolant 25 and the steam flowing in the holding portion 33 reaches a steady state and the heat removal function of the core melt holding device 15A is activated. It has a function to prevent melting of the holding portion 33 during a period of no time. The heat-resistant material 31 is preferably formed using a material having a high melting point that can hold the core melt M. For example, ceramics such as zirconium oxide or aluminum oxide, tungsten, or the like can be used. The heat-resistant material 31 is joined to the holding portion 33 and the riser 34 with an adhesive or the like. In the present embodiment, the heat-resistant material 31 is laid on the holding surface of the holding portion 33 and the entire inner circumference of the riser 34, but the heat-resistant material 31 is provided only on a part of the holding surface of the holding portion 33. Alternatively, it may be laid only on a part of the inner periphery of the riser 34, such as near the bottom surface of the inner periphery of the riser 34.

  The holding part 33 has a cooling passage 35 through which the coolant 25 passes. The cooling passage 35 includes a first passage 36 constituting an inlet side (supply side) of the coolant 25, a second passage 37 constituting an outlet side (discharge side) of the coolant 25, and an outlet portion of the first passage 36. It is formed by a connecting portion 38 that connects the inlet portion of the second passage 37. The cooling passage 35 has a two-layer structure of a first passage 36 and a second passage 37, and the inlet side of the first passage 36 is disposed below the outlet side of the second passage 37. In the embodiment, the entire first passage 36 is disposed below the second passage 37.

  The 1st channel | path 36 is provided in the bottom part of the holding | maintenance part 33, and is connected with 34 A of 1st risers. The second passage 37 is provided closer to the holding surface 32 than the first passage 36 in the holding portion 33 and is connected to the second riser 34B. The connecting portion 38 is a communication opening that allows the first passage 36 and the second passage 37 to communicate with each other inside the holding portion 33.

  A plurality of first communication holes 39 are formed on the side surface of the first passage 36, and a plurality of second communication holes 40 are formed on the side surface of the second passage 37. The first communication hole 39 is a hole that communicates the first passages 36, and the second communication hole 40 is a hole that communicates the second passages 37. Therefore, the coolant 25 flowing in the first passage 36 can pass through the adjacent first passages 36 through the first communication hole 39. The coolant 25 flowing in the second passage 37 can pass through the second communication holes 40 and the adjacent second passages 37. Accordingly, the adjacent first passages 36 are connected to each other through the first communication hole 39, and the adjacent second passages 37 are connected to each other through the second communication hole 4038. The passage 37 is branched in the horizontal direction to form a flow path in the mesh structure.

  The riser 34 is arranged so as to surround the holding portion 33 circumferentially along the inner peripheral surface of the pedestal side wall 17, and has a flow path through which the coolant 25 passes. The riser 34 includes a first riser 34A and a second riser 34B, and the first riser 34A and the second riser 34B are arranged so that their positions in the circumferential direction are different from each other. In the present embodiment, a plurality of first risers 34 </ b> A and second risers 34 </ b> B are alternately arranged along the inner peripheral surface of the pedestal side wall 17. The first riser 34A is a riser connected to the supply side of the cooling passage 35, that is, the first passage 36, and the second riser 34B is a riser connected to the discharge side of the cooling passage 35, that is, the second passage 37. is there. In the present embodiment, the first riser 34 </ b> A is connected to the first passage 36, and the second riser 34 </ b> B is connected to the second passage 37. Although the first riser 34A and the second riser 34B are alternately arranged, the present invention is not limited to this. For example, after arranging two or more first risers 34A, the second riser 34B is arranged. One or more may be arranged side by side.

  The upper end of the second riser 34B is installed at a position higher than the upper end of the first riser 34A, and is higher than the position of the water surface of the coolant 25. Therefore, it is possible to prevent the coolant 25 from entering from the upper end of the second riser 34B and to allow the coolant 25 to enter only from the first riser 34A. Thereby, the coolant 25 in the pedestal 12 can be passed through the first riser 34A, the cooling passage 35, and the second riser 34B in this order.

  The core melt holding device 15A is configured as described above. Before the core melt M falls, the coolant (water) 25 is put into the pedestal 12, and the entire structure including the holding unit 33 and the riser 34 is included. Fill with coolant 25 and cool the entire device. The core in the reactor pressure vessel 14 is melted due to the core melting accident, and the falling core melt M is held by the holding surface 32 of the holding portion 33 on the inner side (inner peripheral side) surrounded by the riser 34.

  When the core melt M is held on the holding surface 32 of the holding unit 33, the coolant 25 in the second passage 37 cools the core melt M held on the holding surface 32 via the holding surface 32. At this time, at least a part of the coolant (water) 25 is vaporized by absorbing the heat of the core melt M by heat exchange with the decay heat of the core melt M, and the gaseous coolant (water vapor) 25. Is generated. The water vapor generated in the second passage 37 and the coolant 25 whose temperature has increased in the second passage 37 flow in the second passage 37 toward the second riser 34B due to the buoyancy generated by the density difference. It rises in the second riser 34B and is discharged upward from the upper part of the second riser 34B.

  Thereby, the coolant (water) 25 in the pedestal 12 is introduced into the first riser 34A, descends in the first riser 34A, and flows toward the first passage 36 side. Then, the coolant 25 flows into the second passage 37 from the connecting portion 38 in the central portion in the holding portion 33 through the first passage 36.

  As described above, in the core melt holding device 15A, the core melt M is caused by the coolant 25 that naturally convects sequentially to the first riser 34A, the first passage 36, the connecting portion 38, the second passage 37, and the second riser 34B. Is cooled, and the entire core melt holding device 15A is also cooled.

  In the present embodiment, the outer shape of the first riser 34A and the second riser 34B when viewed from the vertical axis direction is formed in an arc shape on the inner periphery and the outer periphery, but is not limited thereto. For example, as shown in FIG. 7, the outer shape of the first riser 34A and the second riser 34B when viewed from the vertical axis direction may be a trapezoid. In this case, since the inner periphery of the entire riser 34 is a regular polygon that is nearly circular, the gap with the inner peripheral surface of the pedestal sidewall 17 can be reduced as much as possible. In addition, since the inner circumference of the entire riser 34 can be a regular polygon that is nearly circular, interference with equipment in the lower dry well, such as an elevator, can be easily avoided. In addition, the shape of the first riser 34A and the second riser 34B in the vertical axis direction is not limited to a trapezoidal shape, and the shape of the first riser 34A and the second riser 34B can be a single structure even in other shapes such as a rectangle. I just need it.

  Further, in the present embodiment, the shape of the riser 34 in the vertical direction is a trapezoid and has an outer periphery that opposes the inner peripheral surface of the pedestal side wall 17, but is not limited thereto, and at least one riser 34 is provided. It is good also as a structure which open | releases at least one part by the side of the pedestal side wall of 17 and does not have an outer periphery. When the riser 34 opens the contact surface with the pedestal side wall 17, as shown in FIG. 8, for example, when the existing pipe 41 is arranged in the lower dry well when used in an existing furnace, the existing pipe Since the interference with 41 can be easily avoided, the riser 34 can be easily incorporated into the lower dry well.

  In the present embodiment, the first riser 34A and the second riser 34B are only required to allow the coolant 25 or water vapor to pass through them. For example, as shown in FIGS. 9 and 10, the first riser 34A A convection promoting plate 42 for circulating the coolant 25 in the first riser 34A may be installed therein. When the convection promoting plate 42 is installed in the first riser 34A, the coolant 25 flowing through the space between the inner peripheral wall of the first riser 34A and the convection promoting plate 42 is heated and vaporized by the core melt M. A part of the coolant 25 flowing in the space between the outer peripheral wall of the first riser 34A and the convection promoting plate 42 enters the space between the inner peripheral wall of the first riser 34A and the convection promoting plate 42, and again, It circulates in the space between the outer peripheral wall of the first riser 34A and the convection promoting plate 42. Therefore, since the coolant 25 flowing in the first riser 34A can be circulated around the convection promoting plate 42, the cooling effect of the core melt M can be improved from the first riser 34A side.

  As shown in FIGS. 4 to 6, the holding unit 33 is configured by combining a plurality of core melt holding blocks 32 </ b> A, and the holding surface 32 is formed in the upward direction. The core melt holding block 32A has a plurality of through holes inside, and by combining the plurality of core melt holding blocks 32A, the through holes of the plurality of core melt holding blocks 32A communicate with each other to hold the holding portion. A cooling passage 35 having a first passage 36, a second passage 37, a connecting portion 38, a first communication hole 39, and a second communication hole 40 is formed inside 33. The riser 34 is also formed, for example, by stacking a plurality of blocks similar to the holding portion 33 so that holes extending through the blocks extend in the vertical direction and are connected.

  Further, in the present embodiment, the holding unit 33 is configured by combining the core melt holding blocks 32A that are radially divided. However, if the holding unit 33 is configured to be accommodated in the riser 34, the holding unit 33 is particularly configured. The dividing method of 33 is not limited. For example, as shown in FIG. 11, the holding unit 33 may be configured by combining core melt holding blocks 32 </ b> A divided in a lattice shape.

  As described above, the core melt holding device 15A applied to the reactor containment vessel 11 has the two-layer structure in which the cooling passage 35 provided in the holding portion 33 includes the first passage 36 and the second passage 37 as described above. The first riser 34A is connected to the first passage 36, the second riser 34B is connected to the second passage 37, and the holding portion 33 is surrounded circumferentially along the inner peripheral surface of the pedestal side wall 17. One riser 34A and second riser 34B are alternately arranged to form a single structure. Therefore, it is not necessary to install the first riser 34A and the second riser 34B for each core melt holding block 32A so as to have a double structure, and even if the riser 34 has a single structure, the first passage extends to the entire bottom of the holding part 33. Both 36 and the second passage 37 can be stretched. Thereby, compared with the case where the first riser 34A and the second riser 34B have a double structure, the installation area of the holding portion 33 can be increased and the space where the core melt M spreads can be increased. The cooling efficiency of M can be increased. Therefore, according to the core melt holding device 15A, the core melt M can be cooled and held more stably.

  Further, as described above, the core melt holding device 15A can be easily installed even if the inside of the pedestal 12 is a narrow space by making the riser 34 including the first riser 34A and the second riser 34B into a single structure. Can do.

(Second Embodiment)
A core melt holding device according to a second embodiment will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the member which has the same function as the said embodiment, and detailed description is abbreviate | omitted. Further, the configuration other than the core melt holding device of the reactor containment vessel to which the core melt holding device according to the present embodiment is applied is the same as that of the reactor containment vessel shown in FIG. Therefore, in the present embodiment, only the configuration of the core melt holding device according to the present embodiment will be described.

  FIG. 12 is a schematic view showing the configuration of the core melt holding device according to the present embodiment, and FIG. 13 is a view showing a state where the riser is fixed. As shown in FIGS. 12 and 13, the core melt holding device 15 </ b> B includes first fixing holes (fixing holes) 51 </ b> A and 51 </ b> B provided on the wall surface on the adjacent riser 34 side, and the bottom of the first riser 34 </ b> A. The pedestal floor 16 has a projecting portion 52 that extends to the floor surface and fixes the first riser 34 </ b> A to the floor surface of the pedestal floor 16. In the present embodiment, the first fixing hole 51 </ b> A is provided on the upper side of the wall surface of the riser 34, and the first fixing hole 51 </ b> B is provided on the lower side of the wall surface of the riser 34.

  The first fixing holes 51A and 51B are holes for fixing the adjacent risers 34 to each other with the joining bolts (first fastening parts) 53A and 53B. Adjacent risers 34 are bonded to each other by fixing upper portions of the risers 34 with bonding bolts 53 </ b> A and fixing lower portions of the risers 34 with bonding bolts 53 </ b> B. Before laying the core melt holding block 32A, an instrument or the like for fastening the joining bolts 53A and 53B can be easily inserted from both the upper and lower openings of the riser 34. Therefore, the joining bolts 53A and 53B can be easily inserted. The fastening operation can be easily performed.

  The overhang portion 52 has a second fixing hole 55 that is fixed by an anchor bolt (second fastening component) 54. Since the overhanging portion 52 is in contact with the floor surface of the pedestal floor 16, the overhanging portion 52 can be fixed to the floor surface of the pedestal floor 16 by fastening the second fixing hole 55 through the anchor bolt 54. By fixing the overhang portion 52 to the floor surface of the pedestal floor 16 with the anchor bolt 54, the movement of the riser 34 can be suppressed. Further, before the core melt holding block 32A is laid on the floor surface of the pedestal floor 16, the anchor bolt 54 can be easily fastened. It can be easily fixed to the floor surface of the floor 16.

  When the riser 34 is installed after laying the core melt holding block 32A, there is no opening near the riser 34 for fixing the joining bolt 53B and the anchor bolt 54 for fixing the lower portions of the risers 34. Construction becomes difficult. Therefore, in this embodiment, it is preferable to install the riser 34 on the pedestal floor 16 before the core melt holding block 32A is laid.

  Therefore, the core melt holding device 15B has a structure in which the strength of the entire riser 34 is high by providing the first fixing holes 51A and 51B in the riser 34 and connecting the risers 34 to each other as described above. This eliminates the need to connect each riser 34 to the pedestal sidewall 17. Therefore, since the construction of the riser 34 becomes easy, the core melt holding device 15B can be easily manufactured. Further, as described above, the core melt holding device 15B is provided with the overhanging portion 52 in the first riser 34A and connected to the pedestal floor 16, so that the riser 34 can be used even when vibration occurs, for example, when an earthquake occurs. Can be prevented from jumping upward, for example.

  In the present embodiment, the overhang portion 52 is provided only on the first riser 34A, but it may also be provided on the second riser 34B.

(Third embodiment)
A core melt holding device according to a third embodiment will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the member which has the same function as the said embodiment, and detailed description is abbreviate | omitted. Further, the configuration other than the core melt holding device of the reactor containment vessel to which the core melt holding device according to the present embodiment is applied is the same as that of the reactor containment vessel shown in FIG. Therefore, in the present embodiment, only the configuration of the core melt holding device according to the present embodiment will be described.

  FIG. 14 is a schematic view illustrating the configuration of the core melt holding device according to the present embodiment, and FIG. 15 is a perspective view illustrating a part of the configuration of the core melt holding device. As shown in FIGS. 14 and 15, the core melt holding device 15 </ b> C has a convex portion 57 on the riser 34 side of the heat-resistant material 31, and the riser 34 has a bonding hole 58 corresponding to the convex portion 57. Yes. The heat-resistant material 31 is joined to the riser 34 by fitting the convex portion 57 into the joining hole 58. In the present embodiment, six convex portions 57 are provided on the heat-resistant material 31, but the number is not limited to this, and the number is appropriately adjusted according to the size of the riser 34 and the like.

  The heat-resistant material 31 is bonded to the holding surface 32 of the holding portion 33 by an adhesive, and is fitted and bonded while being bonded to the riser 34 by an adhesive. When the riser 34 and the heat-resistant material 31 are fastened and joined with an adhesive or a bolt, the heat of the core melt M may melt the adhesive or the bolt, and the heat-resistant material 31 may fall on the holding portion 33. is there.

  According to the core melt holding device 15B, the heat-resistant material 31 is fitted and joined by the riser 34 and the convex portion 57, so that the adhesive or bolts are melted by the core melt M and the heat-resistant material 31 is placed on the holding portion 33. Therefore, the core melt M can be held on the holding part 33 more safely.

(Fourth embodiment)
A core melt holding device according to a fourth embodiment will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the member which has the same function as the said embodiment, and detailed description is abbreviate | omitted. Further, the configuration other than the core melt holding device of the reactor containment vessel to which the core melt holding device according to the present embodiment is applied is the same as that of the reactor containment vessel shown in FIG. Therefore, in the present embodiment, only the configuration of the core melt holding device according to the present embodiment will be described.

  FIG. 16 is a schematic diagram showing the configuration of the core melt holding device according to the present embodiment. As shown in FIG. 16, the core melt holding device 15 </ b> D has a buffer material (buffer part) 61 on the holding surface 32 of the holding part 33. The buffer material 61 is for buffering the impact applied to the holding surface 32 due to the fall of the core melt M when the core melt M falls from the reactor pressure vessel 14. The buffer material 61 may be any material that can buffer the impact applied to the holding surface 32 due to the fall of the core melt M. The buffer material 61 is fixed by a fixture 63 connected to a CRD platform 62 of a control rod drive mechanism (CRD: control rod device) that rotates in the pedestal 12.

  By installing the buffer material 61 on the holding surface of the holding unit 33, for example, when the core melt M falls on the holding surface of the holding unit 33, the core melt holding block 32 </ b> A and the heat resistance are affected by the impact of the core melt M dropping. It is possible to prevent the material 31 from being damaged. Moreover, although the buffer material 61 is installed only on the holding surface of the holding portion 33, as shown in FIG. 17, the buffer material 61 may have a rising portion 61 a that extends to a part of the riser 34. Good. By providing the rising portion 61a and suppressing the heat-resistant material 31 provided on the riser 34 by the rising portion 61a, the horizontal movement of the heat-resistant material 31 is suppressed by the rising portion 61a. The material 31 can be prevented from jumping out in the horizontal direction.

  The buffer material 61 can be formed using, for example, stainless steel. When drain water or coolant 25 flows on the upper surface of the buffer material 61, it is desirable that impurities are not taken into these, but even if drain water or coolant 25 containing impurities flows into the buffer material 61, etc. In addition, it is possible to suppress the occurrence of rust or the like due to impurities in the buffer material 61.

  The fixture 63 has a rod-like structure and is formed to be extendable in the vertical direction. The buffer member 61 is fixed on the heat-resistant material 31 by the fixing device 63 extending and the heat-resistant material 31 being pressed by the fixture 63. Since the fixture 63 is formed so as to be extendable in the vertical direction, the buffer material 61 can be fixed during normal operation of the nuclear power generation facility, and the fixture 63 is contracted and separated from the buffer material 61 during the periodic inspection. As a result, the CRD platform 62 can move and the CRD is removed. By fixing the buffer material 61, it is possible to prevent the buffer material 61 from moving upward or the like during an earthquake, for example. In the present embodiment, the lower portion of the fixture 63 is configured to be extendable, but the present invention is not limited thereto, and the upper portion of the fixture 63 or both the upper portion and the lower portion may be configured to be extendable. Good.

  Therefore, according to the core melt holding device 15D, the buffer material 61 is fixed on the heat-resistant material 31 using the fixture 63, so that the buffer material 61 is directed upward by a dynamic load such as during an earthquake or a steam explosion. Can be prevented from moving. In addition, the buffer material 61 can be stably fixed on the heat-resistant material 31 without hindering the function of the CRD platform 62 during the periodic inspection or the operation of the nuclear power generation facility.

(Fifth embodiment)
A core melt holding device according to a fifth embodiment will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the member which has the same function as the said embodiment, and detailed description is abbreviate | omitted. Further, the configuration other than the core melt holding device of the reactor containment vessel to which the core melt holding device according to the present embodiment is applied is the same as that of the reactor containment vessel shown in FIG. Therefore, in the present embodiment, only the configuration of the core melt holding device according to the present embodiment will be described.

  FIG. 18 is a schematic view showing the configuration of the core melt holding device according to the present embodiment. As shown in FIG. 18, the core melt holding device 15 </ b> E has a part of the first passage 36 having a length from the connecting portion to the riser 34 to the connecting portion 38, and between the second passage 37 and the pedestal bed 16. A space S is formed. In the present embodiment, the space S is formed at the position of the drain sump 65 installed on the pedestal floor 16. Further, the first communication hole 39 is not provided in the wall surface on the space S side of the first passage 36, and the coolant 25 is configured not to enter the space S from the first communication hole 39.

  One or more drain sumps 65 are provided on the pedestal floor 16 to collect leaked water that may occur during the operation of the reactor, and to detect leaks from the reactor. The water collected in 65 (drain water) is transferred to the outside of the reactor containment vessel 11 through piping by a pump (not shown) provided on the sump cover 66. An upper portion of the drain sump 65 is covered with a sump cover 66, and the upper surface of the sump cover 66 is higher than the upper surface of the pedestal floor 16.

  When the drain sump 65 is installed on the pedestal floor 16, the core melt holding device is generally disposed on the sump cover 66 of the drain sump 65. On the other hand, in the core melt holding device 15E, the first passage 36 has a length up to the connecting portion 38, and a space S is formed between the second passage 37 and the pedestal bed 16, so that the first passage 36 Is configured so as not to interfere with the drain sump 65. Thereby, according to this embodiment, even if the drain sump 65 is installed in the pedestal floor 16, the holding | maintenance part 33 can be installed on the pedestal floor 16 without receiving interference in a contact part with the sump cover 66. Therefore, the holding part 33 can be stably installed on the pedestal floor 16. Further, since the space S is formed when the sump cover 66 is opened, it is not necessary to disassemble all of the holding portion 33 and the riser 34. Therefore, if only the riser 34 is disassembled, the sump cover 66 is easily opened. be able to.

  In the present embodiment, only the first passage 36 is configured not to interfere with the sump cover 66 of the drain sump 65, but the first riser 34A or the second riser 34B does not interfere with the sump cover 66 as well. You may make it comprise as follows.

  As mentioned above, although several embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various combinations, omissions, replacements, changes, and the like can be made without departing from the scope 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.

10 Reactor Equipment 11 Reactor Containment Vessel 12 Pedestal 13 Core 14 Reactor Pressure Vessel (Reactor Vessel)
15A to 15E Core melt holding device 16 Pedestal floor 17 Pedestal side wall 18 Suppression pool water 21 Core melt cooling device 22 Refuse storage pool 23 Coolant piping 24 Coolant introduction valve 25 Coolant 31 Heat resistant material (heat resistant part)
32 holding surface 33 holding portion 33A core melt holding block 34 riser 34A first riser 34B second riser 35 cooling passage 36 first passage 37 second passage 38 connecting portion 39 first communication hole 40 second communication hole 41 existing piping 42 Convection promoting plate 51A, 51B First fixing hole (fixing hole)
52 Overhang 53A, 53B Joining bolt (first fastening part)
54 Anchor bolt (second fastening part)
55 Second fixing hole 57 Convex part 58 Joining hole 61 Buffer material (buffer part)
61a Rising part 62 CRD platform 63 Fixing tool 65 Drain sump 66 Sump cover M Core melt

Claims (7)

A core melt holding device that is provided in a pedestal surrounded by a pedestal side wall and a pedestal floor and holds and cools a core melt generated by melting a core in a reactor pressure vessel on a holding surface,
A cooling passage through which a coolant for cooling the core melt passes,
A first riser connected to the coolant supply side of the cooling passage;
A second riser connected to the coolant discharge side of the cooling passage;
Comprising
A plurality of the first risers and the second risers are circumferentially arranged along the inner peripheral surface of the pedestal side wall so that the positions in the circumferential direction of the first risers and the second risers are different. A core melt holding device. The cooling passage is
A first passage constituting the supply side and a second passage constituting the discharge side;
The core melt holding device according to claim 1, wherein the supply side of the first passage is disposed below the discharge side of the second passage.   The core melt holding device according to claim 1 or 2, wherein an upper end of the second riser is installed at a position higher than an upper end of the first riser.   The core melt holding device according to any one of claims 1 to 3, wherein at least a part of the riser on the side of the pedestal side wall is opened.   The core melt holding device according to any one of claims 1 to 4, further comprising a convection promoting plate for circulating the coolant in the first riser in the first riser.   Two or more wall surfaces of the first riser or the second riser that are in contact with the first riser or the second riser, and for fixing the adjacent first riser or the second riser with a first fastening part The core melt holding device according to any one of claims 1 to 5, further comprising a fixing hole.   A reactor containment vessel comprising the core melt holding device according to any one of claims 1 to 6, which is disposed on a pedestal bed below the reactor pressure vessel.

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