JP6462501B2 - Drain sump protection structure and containment vessel - Google Patents

Description

  Embodiments of the present invention relate to a drain sump protection structure for protecting a drain sump from a core melt when a core melting accident occurs.

  When a cooling water loss accident occurs in a nuclear reactor, the water level in the reactor pressure vessel may drop and the core may be exposed. In such a case, the reactor is automatically shut down in response to a water level lowering signal, and cooling water is injected into the reactor pressure vessel by the emergency core cooling system (ECCS), and the residual heat of the core is Is removed. This normally prevents a core melting accident.

  However, although the probability is very low, it can be assumed that the emergency core cooling device does not operate and other water injection devices cannot be used. In such a case, if the reactor core is exposed due to a decrease in the reactor water level and sufficient cooling is not performed, the reactor core may be melted.

  When the core melts, the hot core melt melts into the bottom of the reactor pressure vessel (so-called lower mirror), penetrates the bottom, and enters the containment vessel vertically below the reactor pressure vessel. Fall on the provided floor. The fallen core melt reacts with the concrete constituting the floor to generate non-condensable gases such as carbon dioxide and hydrogen, and melts and erodes the concrete. When the pressure of the non-condensable gas in the containment vessel increases, the containment vessel may be damaged. Further, when the above-described melting and erosion of the concrete is continued, the structural strength of the storage container is lowered, and the storage container may be damaged.

  The concrete floor of the containment vessel generally has a drain sump, which is a bottomed hole for collecting the leaked coolant in order to detect coolant leaks that occur during normal operation of the reactor. Is formed. The cooling water collected in the drain sump is discharged out of the containment vessel by a pump or the like.

  When core melting occurs and hot core melt flows into the drain sump, even if cooling water is supplied to the concrete floor of the containment vessel, the cooling water is unlikely to reach the core melt flowing into the drain sump. . In addition, the core melt flowing into the drain sump has a smaller area in contact with the air in the containment vessel than its volume. For this reason, it is difficult to cool the core melt flowing into the drain sump. For this reason, when the core melt flows into the drain sump, there is a risk that the concrete constituting the drain sump will be continuously melted and eroded to damage the containment vessel.

  In order to suppress the inflow of the drain sump of the core melt, a technique for covering the drain sump opening with a heat-resistant cover has been proposed. For example, Patent Document 1 below discloses a cover in which a flow path for allowing drain water to pass is formed. By forming such a flow path in the cover, the core melt flows into the drain sump when a core melting accident occurs while maintaining the function of the drain sump to collect the coolant that has leaked during normal operation. Suppressed.

Japanese Patent No. 5306074

  In order to protect the drain sump from the core melt, it is conceivable to cover the opening of the drain sump and the wall surface defining the drain sump with a member (hereinafter referred to as a heat-resistant member) made of a material having a relatively high melting point. Such a heat-resistant member generally has a brick shape or a tile shape with a side of about several tens of centimeters. For this reason, when providing a heat-resistant member in the wall surface which demarcates a drain sump, and its periphery, it is necessary to affix many heat-resistant members, and the problem that the construction which attaches a heat-resistant member to a drain sump requires time arises. In particular, when a heat-resistant member is attached to a drain sump in a nuclear power plant that has already started operation, there is a demand to attach the above-mentioned heat-resistant member to the drain sump as quickly as possible from the viewpoint of suppressing exposure of workers. is there.

  In addition, when a shake due to an earthquake or the like occurs, there is a problem that a part of the heat-resistant member attached to the drain sump is detached from a predetermined attachment position. There is a demand for a technology that can hold a heat-resistant member at a predetermined mounting position even if a shake due to an earthquake occurs, and reliably prevent the core melt from flowing into the drain sump even if a core melting accident occurs.

  Embodiments of the present invention have been made in view of the above circumstances, and an object of the present invention is to provide a drain sump protection structure capable of suppressing the core melt from flowing into the drain sump during a core melting accident. .

  In order to achieve the above object, a drain sump protection structure according to an embodiment of the present invention is provided on a base member provided vertically above a drain sump opening, and on the base member. A heat-resistant member made of a material having a higher melting point, and a holding member that is provided on the heat-resistant member and is coupled to the base member and holds the heat-resistant member together with the base member, The heat-resistant member is arranged so as to cover the opening of the drain sump.

  Further, the containment vessel for storing the reactor pressure vessel according to the embodiment of the present invention includes a concrete floor provided on the lower side of the reactor pressure vessel, a drain sump formed so as to be recessed downward from the concrete floor, A base member provided above the opening of the drain sump to the concrete floor, a heat-resistant member disposed on the base member and made of a material having a higher melting point than the base member, and provided on the heat-resistant member And a holding member that is coupled to the base member and holds the heat resistant member together with the base member, and the heat resistant member is disposed so as to cover the opening of the drain sump.

  According to the embodiment of the present invention, it is possible to prevent the core melt from flowing into the drain sump at the time of the core melting accident.

It is a section elevation of a containment vessel and a reactor building which have a drain sump protection structure of a 1st embodiment. It is an expanded sectional view around the drain sump where the drain sump protection structure of the first embodiment is installed. It is sectional drawing of the structure for drain sump protection of 1st Embodiment, and is an expanded sectional view of the area | region enclosed with the broken line A in FIG. It is a schematic diagram explaining arrangement | positioning of the various members which comprise the structure for drain sump protection of 1st Embodiment. It is a front view explaining the structure of the spacer which comprises the structure for drain sump protection of 1st Embodiment. It is sectional drawing of the structure for drain sump protection of 2nd Embodiment, and is an expanded sectional view of the area | region enclosed with the broken line A in FIG. It is sectional drawing of the structure for drain sump protection of the modification 1 of 2nd Embodiment, and is an expanded sectional view of the area | region enclosed with the broken line A in FIG. It is sectional drawing of the structure for drain sump protection of the modification 2 of 2nd Embodiment, and is an expanded sectional view of the area | region enclosed with the broken line A in FIG. It is an expanded sectional view around the drain sump where the drain sump protection structure of the third embodiment is installed. It is an expanded sectional view of the drain sump periphery where the drain sump protection structure of the fourth embodiment is installed. It is a perspective view which shows the periphery structure of a holding member among the drain sump protection structures of 5th Embodiment. It is an expanded sectional view around the drain sump where the drain sump protection structure of the sixth embodiment is installed.

  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]
(Configuration of reactor building and containment vessel)
The configuration of the containment vessel and the reactor building having the drain sump protection structure of the first embodiment will be described with reference to FIG. FIG. 1 is a sectional elevational view of a containment vessel and a reactor building having a drain sump protection structure according to the present embodiment. FIG. 2 is an enlarged sectional view around the drain sump where the drain sump protection structure of the present embodiment is installed.

  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.

  As shown in FIG. 1, the reactor building 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). And a containment vessel 20 for storing the reactor pressure vessel 10. In the present embodiment, the reactor pressure vessel 10 is made of stainless steel. On the other hand, the storage container 20 is made of reinforced concrete having a metal 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 2, that is, a so-called core melt. Melt.

  The storage container 20 is partitioned into a dry-well 21 and a wet-well 22. In the containment vessel 20, the wet well 22 is provided with a pool (hereinafter referred to as a pressure suppression pool) 23 that condenses steam (cooling water) discharged 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 walls 25 and 26 that define the wet well 22, a wall that supports the reactor pressure vessel 10 with respect to the floor 24 of the containment vessel 20 (hereinafter referred to as a pedestal wall) is horizontally inside the wall 26 that extends in the vertical direction. 28) is provided. The pedestal wall 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 wall 28 is mainly made of concrete.

  The floor portion 24 of the containment vessel 20 is provided vertically below the reactor pressure vessel 10 and has a floor (hereinafter referred to as a concrete floor) 27 mainly made of concrete. The concrete floor 27 faces the pressure vessel bottom 14 in the vertical direction. In the present embodiment, the concrete floor 27 extends horizontally inside the pedestal wall 28. When core melting occurs, the hot core melt accumulates in the pressure vessel bottom (so-called lower mirror) 14, melts and penetrates the pressure vessel bottom 14, melts down vertically, and flows down to the concrete floor 27. Fall on the top.

  In the present embodiment, in order to cool the core melt that has fallen on the concrete floor 27, a pipe 30 (hereinafter referred to as a water injection line) 30 that supplies cooling water to the concrete floor 27 is provided. In the present embodiment, the water injection line 30 passes through the storage container 20 and the pedestal wall 28 and extends from the outside of the storage container 20 to the vicinity of the concrete floor 27. The water injection line 30 is provided with a valve 32, and by opening the valve 32, it is possible to supply cooling water from the outside of the storage container 20 onto the concrete floor 27.

  The concrete floor 27 is provided with a space for collecting cooling water (so-called leakage water) on the concrete floor 27, a so-called drain sump 40. The drain sump 40 is formed so as to be recessed vertically downward from the concrete floor 27, and is configured to be able to temporarily store the cooling water on the concrete floor 27. In the present embodiment, the drain sump 40 is disposed in the vicinity of the pedestal wall 28.

  In the present embodiment, as shown in FIG. 2, the drain sump 40 has an opening 41 at the same vertical height as the concrete floor 27, a bottom 43 that is vertically below the opening 41 and extends in the horizontal direction, and It is demarcated by a plurality of walls including a side wall 45 extending inward in the vertical direction from the bottom 43 toward the opening 41.

  During normal operation, the cooling water leaked from the piping or the like in the containment vessel 20 flows down on the concrete floor 27 and flows into the drain sump 40 through the opening 41 through the concrete floor 27. Cooling water from the opening 41 flows down along the side wall 45 and accumulates on the bottom 43. By examining the amount of cooling water accumulated in the drain sump 40, it is possible to know whether or not the cooling water is leaking from the piping in the storage container 20 and the amount of the cooling water leaking.

  On the other hand, when a core melt accident occurs and the hot core melt 3 accumulates vertically above the pressure vessel bottom 14 as shown in FIG. 1, the core melt 3 penetrates the pressure vessel bottom 14. It may fall on the concrete floor 27. When such a core melting accident occurs, the valve 32 is opened, and the cooling water from the water injection line 30 is supplied onto the concrete floor 27.

  The core melt that has flowed into the drain sump 40 has an outer surface area smaller than the core melt that spreads on the concrete floor 27. For this reason, even if cooling water is supplied onto the concrete floor 27 from the water injection line 30, the temperature of the core melt flowing into the drain sump 40 is less likely to decrease than that of the core melt on the concrete floor 27. There is a possibility that the core melt flowing into the drain sump 40 continuously melts and erodes the bottom 43 of the drain sump 40 and further flows vertically downward.

(Structure of drain sump protection structure)
The containment vessel 20 of this embodiment is provided with a structure (hereinafter referred to as a drain sump protection structure) 50 that protects the drain sump 40 by suppressing the inflow of the core melt into the drain sump 40 in the event of a core melting accident. This will be described below with reference to FIGS. FIG. 3 is a cross-sectional view of the drain sump protection structure of the present embodiment, and is an enlarged cross-sectional view of a region surrounded by a broken line A in FIG. FIG. 4 is a schematic diagram for explaining the arrangement of various members constituting the drain sump protection structure of the present embodiment. FIG. 5 is a front view for explaining the structure of the spacer constituting the drain sump protection structure of the present embodiment.

  Among the members constituting the drain sump protection structure of the present embodiment, the base member and the holding member, which will be described later, are not hatched in the cross section for easy understanding in each drawing.

  As shown in FIG. 3, the drain sump protection structure 50 includes a member (hereinafter referred to as a base member) 51 that is provided vertically above the opening 41 of the drain sump 40 and covers a part of the opening 41. . The base member 51 is a plate-like member that extends in the horizontal direction, and is also referred to as a “base plate”. The base member 51 is made of a metal material having a relatively high strength. As the metal material constituting the base member 51, for example, stainless steel or carbon steel is used.

  In the present embodiment, the base member 51 is provided vertically above the spacer 60. The spacer 60 is disposed on an edge portion (hereinafter referred to as an opening edge portion) 27 a outside the opening 41 of the drain sump 40 in the concrete floor 27. The spacer 60 is made of a material having a higher melting point than that of the base member 51. As a material constituting the spacer 60, for example, ceramics such as aluminum oxide and zirconium dioxide (so-called zirconia) are used. It should be noted that a refractory metal material such as tungsten can also be used as the material constituting the spacer 60.

  A plurality of the spacers 60 are arranged so as to surround the opening 41 of the drain sump 40 as shown by a one-dot chain line in FIG. In FIG. 4, part of the display of the spacer 60 is omitted for easy understanding. The spacers 60 are arranged without gaps in the horizontal direction.

  As shown in FIG. 5, each spacer 60 has a flow path (hereinafter referred to as a water flow path) capable of guiding cooling water (so-called leakage water) on the concrete floor 27 to the drain sump 40. ing. In the present embodiment, a groove 62 for passing cooling water is formed on the surface of the spacer 60 that contacts the concrete floor 27. The water flow passage is defined by the opening edge 27 a of the concrete floor 27 and the groove 62.

  As shown in FIGS. 3 and 4, a plurality of heat-resistant members 53 are arranged in the horizontal direction on the base member 51. The plurality of heat-resistant members 53 are arranged so as to cover (cover) the opening 41 on a horizontal plane (that is, a horizontal projection plane) as a whole, and the high-temperature core melt 3 falling from above is discharged from the opening 41 to the drain sump 40. It is configured not to penetrate inside. In FIG. 4, part of the display of the heat-resistant member 53 is omitted for easy understanding. The heat-resistant member 53 is made of a material having a higher melting point than the base member 51. As a material constituting the heat-resistant member 53, for example, ceramics such as aluminum oxide and zirconium dioxide are used. Note that a refractory metal material such as tungsten can also be used. The heat-resistant member 53 made of such a material is also referred to as a refractory brick.

  As shown in FIG. 3, the base member 51 has a protruding portion 52 that protrudes upward in the vertical direction from the surface in contact with the heat-resistant member 53. A plurality of protrusions 52 are arranged at predetermined intervals in the horizontal direction. The heat-resistant member 53 is installed between the protrusions 52 adjacent in the horizontal direction. These protrusions 52 restrict the horizontal movement of the heat-resistant member 53 with respect to the base member 51.

  After the plurality of heat-resistant members 53 are arranged on the base member 51, a member (hereinafter referred to as a holding member) 55 that holds the heat-resistant member 53 together with the base member 51 is provided on the heat-resistant member 53. In the present embodiment, the holding member 55 is a plate-like member having substantially the same dimensions as the base member 51, and is configured to cover the upper surface of the heat-resistant member 53.

  The holding member 55 is made of a metal material having a relatively high strength. For example, stainless steel or carbon steel is used as the material constituting the holding member 55. The holding member 55 is coupled to the base member 51 and sandwiches the heat-resistant member 53 between the base member 51 and holds it.

  The base member 51 and the holding member 55 are coupled by bolts 57 and 59 with the heat-resistant member 53 interposed therebetween. The base member 51 and the holding member 55 are formed with through holes through which the bolts 57 and 59 pass, respectively. The bolt 57 is screwed with the nut 58. Further, the two adjacent base members 51 and the two adjacent holding members 55 are connected by welding or the like in the embodiment of FIG. In addition, about the connection of the base members 51 or the holding members 55, you may use a volt | bolt and a nut other than welding. Or if it comprises so that the heat-resistant member 53 may be arrange | positioned between two base members adjacent to a horizontal direction, since it can integrate by the connection by volt | bolts 57 and 59, base members 51 each other or a holding member It can also be set as the structure which 55 is not connected.

  On the other hand, the bolt 59 is configured as a so-called anchor bolt and is fixed to the opening edge portion 27 a of the concrete floor 27. The spacer 60 is formed with a through-hole through which the bolt 59 passes, and is screwed into a female screw embedded in the opening edge portion 27a. Accordingly, the base member 51, the holding member 55, and the spacer 60 are coupled to the concrete floor 27.

  The heat-resistant member 53 is sandwiched and held between the base member 51 and the holding member 55. As shown in FIG. 4, a plurality of base members 51 and holding members 55 that hold a plurality of heat-resistant members 53 are arranged so as to cover the opening 41 of the drain sump 40. The base members 51 and the holding members 55 that are adjacent in the horizontal direction are coupled to each other via a coupling member (not shown).

  As described above, the drain sump protection structure 50 according to the present embodiment has the opening of the drain sump 40 formed on the concrete floor 27 facing the reactor pressure vessel 10 in the vertical direction in the containment vessel 20 shown in FIG. 41 is provided vertically above 41. As shown in FIGS. 2 and 3, the drain sump protection structure 50 is provided on the base member 51 and the base member 51, and is made of a heat resistant material having a higher melting point than the base member 51. A member 53 and a holding member 55 provided on the heat-resistant member 53 and coupled to the base member 51 to hold the heat-resistant member 53 together with the base member 51 are provided.

  As a result, the heat-resistant member 53 made of a material having a high melting point can be held at a predetermined position vertically above the opening 41 of the drain sump 40 to cover the opening 41. It is possible to suppress the core melt in the flow into the drain sump 40. The heat-resistant member 53 can be easily attached to the drain sump 40 by bringing it into the storage container 20 with the heat-resistant member 53 sandwiched between the base member 51 and the holding member 55 in advance. The installation work of the drain sump protection structure 50 in the containment vessel 20 can be performed in a short period of time.

  On the other hand, during normal operation, the cooling water (leakage water) on the concrete floor 27 can be allowed to flow into the drain sump 40 through the water flow path, that is, the groove 62 included in the spacer 60. According to the present embodiment, the heat-resistant member 53 can be arranged so as to cover most of the opening 41 of the drain sump 40 without performing processing such as forming a through hole in the heat-resistant member 53.

  Further, in the present embodiment, the base member 51 is provided with a protrusion 52 that protrudes upward in the vertical direction from the surface in contact with the heat-resistant member 53, and the protrusion 52 is horizontal to the base member 51. The relative movement in the direction was restricted. Thereby, it can prevent that the heat-resistant member 53 remove | deviates from between the base member 51 and the holding member 55 by shaking, such as an earthquake.

  In the present embodiment, a gap is formed between the base member 51 and the holding member 55 on the vertical upper side of the protruding portion 52 of the base member 51 and on the outer side in the horizontal direction of the protruding portion 52. It is also preferable to pack a sand-like or fibrous heat-resistant member (not shown). Thereby, it can suppress that a core melt flows into the drain sump 40 from the clearance gap between the heat-resistant members 53 adjacent to a horizontal direction, or the horizontal direction outer side of the heat-resistant member 53. FIG.

  Furthermore, in the present embodiment, the base member 51 and the holding member 55 are each a flat plate such as a rectangle, and the upper and lower surfaces of the plurality of base members 51 or the plurality of heat-resistant members 53 arranged as a whole of the plurality of holding members 55 are provided. The base member 51 and the holding member 55 are members for sandwiching and holding the heat-resistant member 53 in the upper and lower sides, but are not necessarily rectangular. . That is, as long as the base member 51 and the holding member 55 have a shape that can be held by sandwiching the plurality of heat-resistant members 53 from above and below, the shape of the horizontal plane is various shapes such as a square shape, a cross shape, and a lattice shape. be able to. Although the plurality of heat-resistant members 53 need to be disposed so as to cover (close) the opening 41 of the drain sump 40 as a whole in the horizontal plane, the plurality of base members 51 and the holding members 55 are not necessarily disposed in the horizontal plane as a whole. There is no need to cover the 40 openings 41.

[Second Embodiment]
The drain sump protection structure of the second embodiment will be described with reference to FIG. 6 is a cross-sectional view of the drain sump protection structure of the present embodiment, and is an enlarged cross-sectional view of a region surrounded by a broken line A in FIG. In addition, about the structure substantially common to 1st Embodiment, the code | symbol same or corresponding is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 6, in the drain sump protection structure 50B of the present embodiment, in addition to the base member 51B and the holding member 55B, a through-hole through which the bolt 57 passes is also formed in the heat-resistant member 53B. The base member 51B of the present embodiment does not have the above-described protrusion 52 (see FIG. 3), and the heat-resistant members 53B are arranged on the base member 51B with no gap in the horizontal direction. By fastening the bolt 57, the heat-resistant member 53B is sandwiched and held between the base member 51B and the holding member 55B.

  On the opening edge 27a of the concrete floor 27, a spacer 60 in which a groove 62 for defining a water flow passage is formed is disposed. The base member 51B is disposed on the spacer 60, and the base member 51B, the heat-resistant member 53B, and the holding member 55B are fixed to the opening edge portion 27a by bolts 59.

  According to the present embodiment, the heat-resistant members 53B can be arranged in the horizontal direction without a gap, and the core melt can be more reliably prevented from flowing into the drain sump 40 in the event of a core melting accident. Also according to this aspect, it is possible to prevent the heat-resistant member 53B from coming off between the base member 51B and the holding member 55B due to shaking such as an earthquake.

  In the drain sump protection structure 50B of the present embodiment, the spacer 60 is disposed between the opening edge portion 27a of the concrete floor 27 and the base member 51B. However, the drain sump protection structure according to the present invention is provided. Is not limited to this embodiment.

  For example, unlike the drain sump protection structure 50C of the first modification shown in FIG. 7, the base member 51C is adjacent to the opening edge portion 27a of the concrete floor 27 without providing the spacer 60 (see FIG. 6). It is good also as what arranges.

  The base member 51 </ b> C of the first modification has a water passage for guiding the cooling water on the concrete floor 27 to the drain sump 40. A groove 51a for defining a water flow passage is formed on the surface of the base member 51C in contact with the opening edge 27a of the concrete floor 27. Also according to this aspect, the cooling water on the concrete floor 27 can be led to the drain sump 40 through the water flow channel during normal operation.

  Further, as in the drain sump protection structure 50D of Modification 2 shown in FIG. 8, a heat-resistant member (hereinafter referred to as a surface) for protecting the upper surfaces of the holding member 55B, bolts 57, 59, etc. vertically above the holding member 55B. It is good also as what installs 53D (it describes as a heat-resistant member for protection). The surface-protecting heat-resistant member 53D is made of a material having a higher melting point than the holding member 55B and the bolts 57 and 59, similarly to the heat-resistant member 53B.

  The heat-protecting member 53D for surface protection is bonded to the holding member 55B and the bolts 57 and 59 with an adhesive or mortar (not shown). The drain sump protection structure 50D configured as described above can prevent the holding member 55B, the bolts 57 and 59, and the base member 51B from being melted due to the heat of the core melt in the event of a core melting accident.

[Third Embodiment]
The drain sump protection structure of the third embodiment will be described with reference to FIG. FIG. 9 is an enlarged cross-sectional view around the drain sump where the drain sump protection structure of the present embodiment is installed. In addition, about the structure substantially common to 1st Embodiment, the code | symbol same or corresponding is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 9, the drain sump protection structure 50 </ b> E has a base member with respect to the walls 47 and 48 that define the drain sump 40 in addition to the base member 51, the heat-resistant member 53, the holding member 55, and the spacer 60 described above. The support member 70 that supports the support 51 is provided. The support member 70 is a member that supports the base member 51 from the inside of the drain sump 40. In FIG. 9, more specifically, the support member 70 supports a plurality of portions including the central portion of the base member 51 from the vertically lower side.

  The support member 70 includes a portion (hereinafter, referred to as a pedestal portion) 71 that covers at least a part of the opening 41 of the drain sump 40, and a portion that extends from the pedestal portion 71 toward the base member 51 and extends vertically upward ( (Hereinafter referred to as a column portion) 73. In the present embodiment, the pedestal portion 71 and the column portion 73 are integrally formed to constitute the support member 70. The support member 70 is made of a metal material having a relatively high strength. For example, stainless steel or carbon steel can be used as the metal material constituting the support member 70.

  The pedestal portion 71 has a plate shape that extends in the horizontal direction, and is configured to have a dimension that is substantially the same as or slightly smaller than a wall 48 that defines an edge of the opening 41 of the drain sump 40 (hereinafter referred to as an opening edge wall). ing. The gantry portion 71 has a water flow passage capable of guiding the cooling water on the concrete floor 27 to the drain sump 40. In the present embodiment, a through hole (not shown) for passing the cooling water is provided. A lot).

  The gantry portion 71 configured as described above is disposed on the wall 47 extending inward from the opening edge wall 48 toward the side wall 45, thereby at least a part of the opening 41 of the drain sump 40 (in this embodiment, a large size). Cover part).

  On the other hand, the column portion 73 extends from the gantry portion 71 so as to protrude vertically upward. A plurality of column portions 73 are arranged at predetermined intervals in the horizontal direction. Each column portion 73 supports the above-described base member 51 from the vertically lower side. The spacer 60 described above supports the base member 51 from the vertically lower side with respect to the opening edge portion 27 a of the concrete floor 27.

  In the drain sump protection structure 50E configured as described above, the cooling water (leakage water) on the concrete floor 27 is passed through the water flow path of the spacer 60 and the water flow of the gantry portion 71 during normal operation. It can be made to flow into the drain sump 40 through the use channel. On the other hand, in the drain sump protection structure 50E, even if the core melt accumulates on the holding member 55 in the event of a core melting accident, the support member 70 supports the base member 51 from the vertically lower side, thereby melting the core. Can withstand the weight of objects.

[Fourth Embodiment]
The drain sump protection structure of the fourth embodiment will be described with reference to FIG. FIG. 10 is an enlarged cross-sectional view around the drain sump where the drain sump protection structure of this embodiment is installed. In addition, about the structure substantially common to 1st and 3rd embodiment, the code | symbol same or corresponding is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 10, the drain sump protection structure 50F supports the base member 51 against the wall that defines the drain sump 40 in addition to the base member 51, the heat-resistant member 53, the holding member 55, and the spacer 60 described above. Supporting members 75 and 77 are provided as supporting members. That is, the columns 75 and 77 are support members that support the base member 51 from the inside of the drain sump 40, and specifically, a column (hereinafter, referred to as a long column) 75 that extends in the vertical direction from the bottom 43 of the drain sump 40. And a column (hereinafter referred to as a short column) 77 extending in a vertical direction from a wall 47 that is vertically above the bottom 43 among the walls that define the drain sump 40.

  A plurality of long columns 75 are provided at predetermined intervals in the horizontal direction inside the drain sump 40 in the horizontal direction. On the other hand, a short column 77 is provided on the drain sump 40 in the horizontal direction outside, that is, in the vicinity of the opening edge wall 48. The long column 75 supports a plurality of portions including the central portion of the base member 51. The short column 77 supports the end of the base member 51 in the horizontal direction.

  According to this embodiment, even if the weight of the core melt deposited on the holding member 55 is relatively large without providing the above-described gantry portion 71 (see FIG. 9), the weight can be withstood. it can.

[Fifth Embodiment]
A drain sump protection structure according to a fifth embodiment will be described with reference to FIGS. 2 and 11. FIG. 11 is a perspective view showing the peripheral structure of the holding member in the drain sump protection structure of the present embodiment. In addition, about the structure substantially common to 1st Embodiment, the code | symbol same or corresponding is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 11, in the drain sump protection structure 50 </ b> G according to the present embodiment, a pipe 36 extends through the holding member 55. The pipe 36 is, for example, for discharging cooling water (leakage water) accumulated at the bottom 43 of the drain sump 40 (see FIG. 2) to the outside of the drain sump 40, and includes a holding member 55 and a base member 51 (see FIG. 2). ) To extend vertically.

  The drain sump protection structure 50G of the present embodiment includes a heat-resistant member (hereinafter referred to as a seam-protecting heat-resistant member) 38 that covers the joint between the holding member 55 and the pipe 36. The seam protection heat-resistant member 38 is made of a material having a higher melting point than the holding member 55. For example, ceramics such as aluminum oxide and zirconium dioxide are used as the material constituting the seam protection heat-resistant member 38. Note that a refractory metal material such as tungsten can also be used. In the present embodiment, the seam protection heat-resistant member 38 has a substantially annular shape and is provided on the holding member 55 coaxially with the pipe 36.

  According to the present embodiment, it is possible to prevent the core melt from melting the joint between the holding member 55 and the pipe 36 and flowing into the drain sump 40 from the melted joint.

  In the present embodiment, the seam protection heat-resistant member 38 has a substantially annular shape, but the seam protection heat-resistant member according to the present invention is not limited to this aspect. The heat-protecting member for seam protection only needs to be configured to cover the seam between the pipe 36 and the holding member 55. For example, the seam-protecting heat-resistant member may have a substantially cylindrical shape surrounding the outside of the pipe 36.

[Sixth Embodiment]
The drain sump protection structure of the sixth embodiment will be described with reference to FIG. FIG. 12 is an enlarged cross-sectional view around the drain sump where the drain sump protection structure of this embodiment is installed. In addition, about the structure substantially common to 1st Embodiment, the code | symbol same or corresponding is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 12, a drain sump protection structure 50 having a base member 51, a heat resistant member 53, a holding member 55, and a spacer 60 is provided vertically above the opening 41 of the drain sump 40. Further, in the present embodiment, in addition to the drain sump protection structure 50, drain sump protection structures 80 and 90 are provided along the wall defining the drain sump 40 and protecting the wall. Specifically, a bottom protection structure 80 that protects the bottom 43 by covering the bottom 43 that defines the drain sump 40 and a side wall protection structure 90 that protects the side wall 45 by covering the side wall 45 are provided. doing.

  The bottom protecting structure 80 has a wall-side base member 81 provided along the bottom 43 among the walls that define the drain sump 40. In addition, the bottom protecting structure 80 is provided on the wall-side base member 81, and the heat-resistant member 83 made of a material having a higher melting point than the wall-side base member 81, and the heat-resistant member 83, and a holding member 85 that is coupled to the wall-side base member 81 and holds the heat-resistant member 83 together with the wall-side base member 81.

  Similarly, the side wall protection structure 90 is provided on the wall side base member 91 provided along the side wall 45 among the walls that define the drain sump 40, and on the wall side base member 91. A heat-resistant member 93 made of a material having a higher melting point than that of the base member 91, is provided on the heat-resistant member 93, is coupled to the wall-side base member 91, and the heat-resistant member 93 together with the wall-side base member 91. And a holding member 95 that holds the member 93.

  The above-described wall-side base members 81 and 91 are configured substantially the same as the above-described base member 51 (except for the dimensions). The heat-resistant members 83 and 93 are configured substantially the same as the heat-resistant member 53 described above, and the holding members 85 and 95 are configured substantially the same as the holding member 55 described above.

  Of the walls defining the drain sump 40, the bottom 43 is covered with the heat-resistant member 83 sandwiched between the wall-side base member 81 and the holding member 85. Similarly, the side wall 45 is covered with the heat-resistant member 93 sandwiched between the wall-side base member 91 and the holding member 95.

  According to the present embodiment, even if the core melt breaks a part of the drain sump protection structure 50 and flows into the drain sump 40, the bottom 43 and the side wall 45, which are walls defining the drain sump 40, It can suppress melting and erosion by the core melt.

  In the present embodiment, both the bottom 43 and the side wall 45 that define the drain sump 40 are covered with heat-resistant members 83 and 93 sandwiched between the wall-side base members 81 and 91 and the holding members 85 and 95, respectively. However, the present invention is not limited to this embodiment. At least one of the bottom 43 and the side wall 45 that defines the drain sump 40 may be covered with the heat-resistant member.

[Other Embodiments]
In the above-described embodiment, the holding member 55 is a plate-like member having substantially the same dimensions as the above-described base member 51 and is configured to cover the heat-resistant member 53, but according to the present invention. The holding member is not limited to this mode. The holding member may be combined with the base member and can hold the heat-resistant member between the holding member and the base member. For example, the holding member may have a beam shape. Also, the base member according to the present invention may be any member as long as it can hold the heat-resistant member together with the holding member, and can be a member having various shapes other than the plate-like member. For example, like the holding member, it may have a beam shape.

  In the embodiment, the base member 51 and the holding member 55 are formed with through holes through which the bolts pass. The base member 51 and the holding member 55 are coupled by the bolts 57 with the heat-resistant member 53 interposed therebetween. However, the method of joining the base member and the holding member in the drain sump protection structure according to the present invention is not limited to this mode. The base member and the holding member may be coupled by welding or the like, for example.

  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.

DESCRIPTION OF SYMBOLS 1 Reactor building, 2 Core, 3 Core melt, 10 Reactor pressure vessel, 12 Cylindrical part, 14 Pressure vessel bottom part, 16 Top part, 20 Containment vessel, 21 Dry well, 22 Wet well, 23 Pressure suppression pool, 24 Floor, 25, 26 wall, 27 concrete floor, 27a opening edge, 28 pedestal wall, 30 water injection line, 32 valve, 36 piping, 38 heat-resistant member for seam protection, 40 drain sump, 41 opening, 43 bottom, 45 side wall, 47 Wall, 48 Open edge wall (wall), 50, 50B, 50C, 50D, 50E, 50F, 50G Drain sump protection structure, 51, 51B, 51C Base member, 51a Groove (flow channel for water flow), 52 Projection Part, 53, 53B heat-resistant member, 53D heat-resistant member for surface protection, 55, 55B holding member, 57 bolt, 58 nut, 59 bolts (anchor bolts), 60 spacers, 62 grooves (flow channels for water flow), 70 support members, 71 mount parts (support members), 73 support columns (support members), 75 long columns (supports), 77 short columns (Support), 80 bottom protection structure (drain sump protection structure), 81 wall side base member, 83 heat-resistant member, 85 holding member, 90 side wall protection structure (drain sump protection structure), 91 wall side base Member, 93 heat-resistant member, 95 holding member

Claims (10)

A base member provided vertically above the drain sump opening;
A heat-resistant member provided on the base member and made of a material having a higher melting point than the base member;
A holding member that is provided on the heat-resistant member and is coupled to the base member and holds the heat-resistant member together with the base member;
With
The heat-resistant member is disposed so as to cover the opening of the drain sump. The base member and the holding member are formed with through holes through which bolts pass,
2. The drain sump protection structure according to claim 1, wherein the base member and the holding member are coupled by the bolt with the heat-resistant member interposed therebetween. The base member is provided so as to protrude upward in the vertical direction from a surface in contact with the heat-resistant member, and has a protrusion capable of restricting relative movement of the heat-resistant member in the horizontal direction with respect to the base member. The drain sump protection structure according to claim 1 or 2. The heat-resistant member has a through-hole through which the bolt passes,
3. The drain sump protection structure according to claim 2, wherein the heat-resistant members are arranged in the horizontal direction without any gap. A spacer provided on an opening edge around the opening, made of a material having a higher melting point than the base member, and having a water passage for guiding water from around the opening to the inside of the drain sump; Prepared,
The drain sump protection structure according to any one of claims 1 to 4, wherein the base member is disposed on the spacer. The said base member is arrange | positioned on the opening edge part of the circumference | surroundings of the said opening, and has the flow path for water flow which guides the water from the circumference | surroundings of the said opening to the said drain sump. Item 5. The drain sump protection structure according to any one of Items 4 to 5. The drain sump protection structure according to any one of claims 1 to 4, further comprising a support member that supports the base member from the inside of the drain sump. The holding member has a pipe extending therethrough,
The heat-resistant member for seam protection, which is made of a material having a higher melting point than that of the holding member and covers the joint between the holding member and the pipe, is further provided. The drain sump protection structure according to any one of the above. A wall-side base member provided along a wall defining the drain sump;
A heat-resistant member that is provided on the wall-side base member and is made of a material having a higher melting point than the wall-side base member;
A holding member that is provided on the heat-resistant member and is coupled to the wall-side base member and holds the heat-resistant member together with the wall-side base member;
With
The drain sump according to any one of claims 1 to 8, wherein a wall defining the drain sump is covered with the heat-resistant member sandwiched between the wall-side base member and the holding member. Protective structure. A containment vessel for storing a reactor pressure vessel,
A concrete floor provided under the reactor pressure vessel;
A drain sump formed to dent downward from the concrete floor;
A base member provided above the opening of the drain sump to the concrete floor;
A heat-resistant member arranged on the base member and made of a material having a higher melting point than the base member;
A holding member provided on the heat-resistant member and coupled to the base member to hold the heat-resistant member together with the base member;
The containment container, wherein the heat-resistant member is disposed so as to cover the opening of the drain sump.

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