JP2011169744A - Device for holding of core molten material, and containment vessel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce possibility of breakage of a core molten material holding device due to thermal stress is reduced. <P>SOLUTION: The core molten material holding device holding core molten material generated when a core contained in a reactor pressure vessel melted to fall down includes a water supply container prepared under the reactor pressure vessel to supply cooling water and a cooling flow channel organizer forming a cooling flow channel extending from the water supply container. The cooling flow channel organizer includes an inclination channel top panel 17, an inclination channel bottom panel 16, a riser section inside plate 18, and a riser section outside plate 19. Between the inclination channel top panel 17 and the inclination channel bottom panel 16 an inclination section of the cooling flow channel is formed. Between the riser section inside plate 18 and the riser section outside plates 19 a riser section of the cooling flow channel is formed. The riser section inside plate 18 is loaded merely on a circumference of the inclination channel top panel 17, without, for example, welding or the like, to prepare movably relative to the inclination channel top panel 17 when the core molten material falls down. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a core melt holding device for holding a core melt generated when a core contained in a reactor pressure vessel is melted and dropped, and a containment vessel using the core melt holding device.

  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 reactor water level falls and the reactor core is exposed and cooled. It may become insufficient. Assuming such a case, the reactor is automatically shut down in response to a water level lowering signal, and the core is submerged and cooled by injecting coolant using an emergency core cooling system (ECCS), and a core melting accident is performed. It is designed to prevent it.

  However, although the probability is very low, it may be assumed that the emergency core cooling device does not operate and the water injection device for other cores cannot be used. In such a case, the core is exposed due to a decrease in the reactor water level, and sufficient cooling is not performed, and the fuel rod temperature rises due to decay heat that continues to occur after the reactor shuts down, eventually leading to core melting. It is possible.

  When such a situation occurs, the hot core melt (corium) melts into the lower part of the reactor pressure vessel, and further melts through the reactor pressure vessel lower mirror and falls onto the floor in the containment vessel. . The core melt heats the concrete stretched on the containment floor. When the contact surface between the containment floor and the core melt reaches a high temperature, the core melt and concrete react to generate a large amount of non-condensable gases such as carbon dioxide and hydrogen, and the concrete is melted and eroded. .

  The generated non-condensable gas increases the pressure in the containment vessel and may damage the reactor containment vessel. In addition, there is a possibility that the containment vessel boundary may be damaged or the containment vessel structural strength may be reduced due to concrete erosion. As a result, if the reaction between the core melt and concrete continues, the containment vessel may be damaged, and the radioactive material in the containment vessel may be released to the external environment.

  In order to suppress the reaction between the core melt and the concrete, the core melt is cooled and the temperature of the contact surface with the concrete at the bottom of the core melt is cooled below the erosion temperature, or the core melt and the concrete are directly It is necessary to avoid contact. The erosion temperature is 1500 K or less for general concrete.

  For this reason, countermeasures in preparation for the case where the core melt falls are disclosed (for example, see Patent Document 1 and Patent Document 2). A typical one is installation of what is called a core melt holding device (core catcher). The core melt holding device is a facility that receives a fallen core melt with a heat-resistant material and cools the core melt in combination with water injection means.

  Even if cooling water is poured onto the top surface of the core melt that has fallen to the reactor containment floor, if the amount of heat removal at the bottom of the core melt is small, the temperature at the bottom of the core melt will be maintained high due to decay heat. From the idea that the concrete erosion of the containment floor cannot be stopped, there is a method of cooling the core melt from the bottom surface.

Japanese Patent No. 3554001 JP 2007-232529 A

  When cooling with water injection, only water injection from the top of the core melt is only cooling by boiling the water on the top surface of the core melt, and if the core melt deposition thickness is thick, cooling to the bottom of the core melt is not possible. There is sex. Therefore, it is necessary to increase the floor area and to reduce the corium deposition thickness to a thickness that can be cooled. However, securing a sufficiently large floor area has been difficult in designing the containment structure.

For example, the decay heat of a typical core melt is about 1% of the rated heat output, and in the case of a furnace with a rated heat output of 4000 MW, the calorific value is about 40 MW. Although the amount of boiling heat transfer on the upper surface varies depending on the state of the upper surface of the core melt, a heat flux of at least about 0.4 MW / m ² is assumed. In this case, if the heat generation amount of the core melt is taken only by heat transfer from the top surface, a floor area of about 100 m ² (circular diameter of 11.3 m) is required. Considering the structure of the conventional containment vessel, it has been difficult to secure this area.

  On the other hand, there is a method of removing heat from the bottom surface of the core melt by providing a cooling water flow path below the core melt deposition floor surface and guiding the cooling water here. However, the temperature of the structural material of the cooling water flow path rises due to the high-temperature core melt, and as the temperature rises, thermal stress is generated in the structural material of the cooling water flow path, and the cooling water flow path may be damaged.

  Accordingly, an object of the present invention is to reduce the possibility of damage to the core melt holding device due to thermal stress.

  In order to achieve the above-described object, the present invention provides a core melt holding device for holding a core melt generated when a core contained in a reactor pressure vessel is melted and dropped, below the reactor pressure vessel. A water supply container to which cooling water is supplied, a top plate that spreads radially from the water supply container, and a core plate that is movable relative to the top plate when the core melt falls. A cylindrical riser portion inner plate that rises from the outer peripheral portion of the top plate, and an inclined portion that contacts the lower surface of the top plate, and a riser portion that is connected to the inclined portion and contacts the outer surface of the riser portion inner plate. And a cooling flow path forming body that forms a cooling flow path extending from the water supply container.

  Further, the present invention provides a containment vessel for storing a reactor pressure vessel containing a reactor core, a pedestal floor, a pedestal side wall surrounding the pedestal floor and extending vertically upward to support the reactor pressure vessel, and the pedestal floor A water supply container that is provided on the top and is supplied with cooling water, a top plate that spreads radially from the water supply container, and is movable relative to the top plate when the core melt falls. A cylindrical riser portion inner plate that is provided and rises from an outer peripheral portion of the top plate, and is in contact with the lower surface of the top plate and connected to the inclined portion and in contact with the outer surface of the riser portion inner plate And a cooling flow path forming body that forms a cooling flow path extending from the water supply container.

  According to the present invention, the possibility of damage to the core melt holding device due to thermal stress is reduced.

It is the perspective view which extracted a part of 1st Embodiment of the core melt holding | maintenance apparatus which concerns on this invention. FIG. 3 is an elevational sectional view of the vicinity of the core melt holding device in the first embodiment of the core melt holding device according to the present invention. 1 is a partial cross-sectional view of a first embodiment of a core melt holding device according to the present invention. It is an elevation sectional view of a containment vessel which stored a 1st embodiment of a core melt maintenance device concerning the present invention. It is a partially expanded sectional view in 2nd Embodiment of the core melt holding | maintenance apparatus which concerns on this invention. It is a partially expanded sectional view in 3rd Embodiment of the core melt holding | maintenance apparatus which concerns on this invention. It is the expanded sectional view which extracted a part of 4th Embodiment of the core melt holding | maintenance apparatus which concerns on this invention. It is the perspective view which extracted a part of 5th Embodiment of the core melt holding | maintenance apparatus which concerns on this invention. It is the perspective view which extracted a part of 6th Embodiment of the core melt holding | maintenance apparatus which concerns on this invention. It is the perspective view which extracted a part of 7th Embodiment of the core melt holding | maintenance apparatus which concerns on this invention. It is the perspective view which extracted a part of 8th Embodiment of the core melt holding | maintenance apparatus which concerns on this invention. It is the perspective view which extracted a part of 9th Embodiment of the core melt holding | maintenance apparatus which concerns on this invention. It is the perspective view which extracted a part of 10th Embodiment of the core melt holding | maintenance apparatus which concerns on this invention.

  An embodiment of a core melt holding device according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or similar structure, and the overlapping description is abbreviate | omitted.

[First Embodiment]
FIG. 4 is an elevational sectional view of a containment vessel containing the first embodiment of the core melt holding device according to the present invention.

  The core 43 is housed inside the reactor pressure vessel 1. The reactor pressure vessel 1 is provided inside the containment vessel 2. The containment vessel 2 has a pedestal floor 41 and a cylindrical pedestal side wall 42 extending upward from the pedestal floor 41.

  The reactor pressure vessel 1 is supported on the pedestal side wall 42. The space surrounded by the pedestal floor 41 and the pedestal side wall 42 below the reactor pressure vessel 1 is called a lower dry well 7. That is, the reactor pressure vessel 1 is provided above the lower dry well 7. A suppression pool 4 is formed inside the storage container 2 so as to surround the outer peripheral surface of the pedestal side wall 42.

  A core melt holding device 9 is provided in the lower dry well 7 below the reactor pressure vessel 1. A sump bed 8 is provided between the core melt holding device 9 and the reactor pressure vessel 1.

  Further, the storage container 2 has a water tank 5. A water injection pipe 14 extends from the water tank 5 to the core melt holding device 9. A valve 40 is provided in the middle of the water injection pipe 14. Further, the storage container 2 has a storage container cooler 6. The containment vessel cooler 6 has a pipe extending from the end opened to the dry well to the water tank 5 through a heat exchanger submerged in water. The containment vessel cooler 6 is a static containment vessel cooling facility, a dry well cooler, or the like.

  FIG. 1 is a perspective view of a part of the core melt holding device in the present embodiment. FIG. 2 is an elevational sectional view of the vicinity of the core melt holding device in the present embodiment. FIG. 3 is a partial cross-sectional view of the core melt holding device in the present embodiment. FIG. 2 shows a state in which the core melt 13 has fallen onto the core melt holding device 9 and is supplied from the water tank 5 to the core melt holding device 9.

  The core melt holding device 9 has a water supply container 10. The water supply container 10 is formed in a cylindrical shape, for example, and is disposed, for example, in the center of the pedestal floor 41. A water injection pipe 14 extending from the water tank 5 is connected to the water supply container 10.

  A cooling flow path 11 through which cooling water for cooling the core melt 13 flows is formed inside the core melt holding device 9. The cooling flow path forming body 51 that forms the cooling flow path 11 includes at least the inclined flow path top plate 17 and the riser portion inner plate 18.

  The inclined flow path top plate 17 spreads radially while rising from the water supply container 10. The inclined channel top plate 17 is formed by, for example, arranging a plurality of portions formed in a fan shape closely around the water supply container 10. The upper surface of the inclined channel top plate 17 has a shape obtained by cutting out the top of a conical surface that rises from the center toward the outer periphery. A pair of flow path support guides 22 projecting downward and extending in parallel are provided on the lower surface of the inclined flow path top plate 17.

  The riser portion inner plate 18 rises vertically upward from the outer peripheral portion of the inclined channel top plate 17. The riser portion inner plate 18 is placed on the outer peripheral portion of the inclined channel top plate 17 and is provided so as to be movable relative to the inclined channel top plate 17.

  The upper surface of the inclined flow path top plate 17 having a shape obtained by cutting the top portion of the conical surface and the inner surface of the cylindrical riser portion inner plate 18, that is, the entire inner wall surface of the container portion holding the core melt 13 and the entire upper surface of the water supply container, Covered with a heat-resistant material 12.

  The cooling flow path forming body 51 further includes an inclined flow path bottom plate 16 and a riser section outer plate 19. The inclined channel bottom plate 16 is provided such that the upper surface thereof faces the lower surface of the inclined channel top plate 17. The inclined channel bottom plate 16 is formed by, for example, arranging a plurality of portions formed in a fan shape closely around the water supply container 10. The upper surface of the inclined channel bottom plate 16 has a shape obtained by cutting out the top of a conical surface that rises from the center toward the outer periphery.

  On the upper surface of the inclined channel bottom plate 16, a channel support 21 that protrudes vertically upward and extends in the radial direction is provided. The inclined flow path top plate 17 is disposed so that the upper end of the flow path support 21 is located between the pair of flow path support guides 22 and is placed on the flow path support 21. The riser part outer plate 19 rises vertically upward from the outer peripheral part of the inclined flow path bottom plate 16, and is provided so that the inner surface faces the outer surface of the riser part inner plate 18.

  By such a cooling flow path forming body 51, an inclined portion between the inclined flow path bottom plate 16 and the inclined flow path top plate 17, and a riser portion between the riser portion outer plate 19 and the riser portion inner plate 18 are provided. A cooling flow path 11 is formed which extends from the water supply container 10 to the opening opened to the lower dry well 7 at the upper end of the riser section. Further, a water supply flow path 15 is formed between the riser portion outer plate 19 and the pedestal side wall 42. The water supply channel 15 extends from the opening opened to the lower dry well 7 to the water supply container 10.

  When a core melting accident occurs and the core melt 13 penetrates the lower head 3 of the reactor pressure vessel 1, it falls onto the core melt holding device 9. Immediately after the core melt 13 is dropped, the injection valve 40 is opened, and the cooling water in the water tank 5 is supplied to the water supply container 10 via the water injection pipe 14 due to gravity dropping. The injection valve 40 is opened by a signal for detecting breakage of the lower head 3 of the reactor pressure vessel 1, for example. The signal for detecting the breakage of the lower head 3 of the reactor pressure vessel 1 is, for example, a signal indicating that the lower head temperature is high or the pedestal atmosphere temperature is high. Thus, the initial water supply to the water supply container 10 is performed immediately after the core melt 13 is dropped, and the cooling water is supplied to the cooling flow path 11.

  The water supplied to the cooling channel 11 is supplied from the opening at the upper end of the riser unit to the container part that holds the core melt of the melting core cooling device 9, that is, the upper surface of the inclined channel top plate 17 and the riser unit inner plate 18. It overflows into the area surrounded by the inner surface. Further, the entire core melt holding device 9 is submerged.

  After completion of the initial water injection, the water that overflows into the container portion that holds the core melt 13 of the core melt holding device 9 passes through the water supply passage 15 by the natural circulation caused by boiling in the cooling flow passage 11. To be supplied.

  The steam generated by cooling the core melt 13 is condensed by the containment vessel cooler 6 above the containment vessel 2, and the condensed water is returned to the water tank 5. Thus, cooling of the core melt 13 is continued by natural circulation of water.

  The heat of the hot core melt 13 is transferred to the heat-resistant material 12 and further transferred to the cooling water through the cooling flow path 11. Thereby, the core melt 13 is cooled. At this time, thermal expansion occurs as the temperature of the cooling flow path forming body 51 rises. In particular, the amount of thermal expansion of the inclined flow path top plate 17 close to the core melt 13 is large. On the other hand, the riser section inner plate 18 is farther from the core melt 13 than the inclined channel top plate 17, so the temperature rise is small and the amount of thermal expansion is small.

  When each part of the cooling flow path forming body 51 is constrained, thermal stress is generated. However, in the present embodiment, the riser section inner plate 18 is simply put on the inclined flow path top plate 17, that is, the deformation is not restrained by welding them together. The thermal expansion of the road top plate 17 is not restrained by the riser inner plate 18. That is, the difference in thermal expansion between the inclined flow path top plate 17 and the riser portion inner plate 18 can be absorbed by the connecting portion 20 between them.

  Further, since the inclined channel bottom plate 16 is farther from the core melt 13 than the inclined channel top plate 17, the temperature rise is small and the amount of thermal expansion is small. However, the inclined channel top plate 17 is simply placed on the channel support 21, and the inclined channel top plate 17 and the inclined channel bottom plate 16 have a structure that does not restrain deformation. For this reason, the thermal expansion difference between the inclined channel top plate 17 and the inclined channel bottom plate 16 can be supplied by the inclined channel top plate 17 sliding along the channel support 21.

  Thus, in this Embodiment, the thermal stress which generate | occur | produces in the structure which forms the cooling flow path 11 at the time of fall of the core melt 13 can be reduced. Thus, the possibility of damage to the core melt holding device is reduced.

[Second Embodiment]
FIG. 5 is a partially enlarged sectional view of the core melt holding device according to the second embodiment of the present invention.

  The core melt holding device of the present embodiment is different from the first embodiment in the structure of the heat-resistant material 12 (see FIG. 3). In the core melt holding device of the present embodiment, the heat-resistant material is composed of an inclined portion heat-resistant material 61, a riser portion heat-resistant material 62 and a granular heat-resistant material 23. The inclined portion heat-resistant material 61 is laid on the inclined flow path top plate 17. The riser part heat-resistant material 62 is laid on the inner surface of the riser part inner plate 18. The granular heat-resistant material 23 is disposed at a boundary portion between the inclined portion heat-resistant material 61 and the riser heat-resistant material 62.

  When holding the core melt 13 (see FIG. 3), each of the inclined flow path top plate 17 and the riser portion inner plate 18 is deformed by thermal expansion. The heat-resistant material inclined portion 61 is laid so as to move and deform according to the deformation of the inclined flow path top plate 17, and the heat-resistant material riser portion 62 moves and deforms according to the deformation of the riser portion inner plate 18. Lay down.

  Also in the present embodiment, similarly to the first embodiment, the thermal stress in the cooling flow path 11 is reduced by adopting a structure that does not restrain the thermal expansion of the inclined flow path top plate 17 and the riser portion inner plate 18. Can be reduced.

  Further, when deformation and displacement of the heat-resistant material due to thermal expansion or the like are constrained, the deformation and displacement of the inclined flow path top plate 17 and the riser portion inner plate 18 may be constrained accordingly. However, in the present embodiment, the granular heat resistant material laid on the boundary portion between the inclined portion heat resistant material 61 and the riser heat resistant material 62, that is, above the connection portion 20 between the inclined flow path top plate 17 and the riser inner plate 18. Since 23 is granular, it can be easily moved. For this reason, the deformation | transformation and displacement of the heat-resistant material inclination part 61 and the heat-resistant material riser part 62 can be absorbed in the part by which the granular heat-resistant material 23 was laid. As a result, it is possible to further reduce the thermal stress generated in the structure forming the cooling flow path 11 when the core melt falls. Thus, the possibility of damage to the core melt holding device is reduced.

[Third Embodiment]
FIG. 6 is a partially enlarged sectional view in the third embodiment of the core melt holding device according to the present invention.

  The core melt holding device of the present embodiment uses a fibrous heat-resistant material 24 instead of the granular heat-resistant material 23 (see FIG. 5) in the second embodiment. In the present embodiment, similarly to the first embodiment, the core melt in the cooling flow path 11 is structured by not constraining the thermal expansion of the inclined flow path top plate 17 and the riser inner plate 18. It is possible to reduce the thermal stress when the water drops.

  Similarly to the second embodiment, the deformation and displacement of the heat-resistant material inclined portion 61 and the heat-resistant material riser portion 62 can be absorbed by the portion where the fibrous heat-resistant material 24 is laid. As a result, it is possible to further reduce the thermal stress generated in the structure forming the cooling flow path 11 when the core melt falls. Thus, the possibility of damage to the core melt holding device is reduced.

[Fourth Embodiment]
FIG. 7 is an enlarged vertical sectional view showing a part of the fourth embodiment of the core melt holding device according to the present invention.

  The core melt holding device of the present embodiment is different from the first embodiment in the relative size relationship between the inclined channel top plate 17 and the riser inner plate 18. In the present embodiment, the inclined flow path top plate 17 whose outer edge is on the outer peripheral side of the connection portion 20 with the riser portion inner plate 18 is used.

  By installing the cylindrical riser inner plate 18 on the inner side of the outer edge of the dish-shaped inclined flow path top plate 17, even if an earthquake occurs, the riser inner plate 18 and the inclined flow The possibility that the road top plate 17 is displaced can be reduced.

  Thus, in the present embodiment, the heat in the cooling flow path 11 is obtained by adopting a structure that does not restrain thermal expansion when the core melt of the inclined flow path top plate 17 and the riser inner plate 18 falls. Stress can be reduced. Thus, the possibility of damage to the core melt holding device is reduced. Furthermore, the shift | offset | difference of the riser part at the time of an earthquake can be reduced.

[Fifth Embodiment]
FIG. 8 is a perspective view of a part extracted from the fifth embodiment of the core melt holding device according to the present invention.

  The core melt holding device of the present embodiment is obtained by adding a support part 25, a flow path support part 26, and a lift prevention part 27 to the first embodiment. The support portion 25 is fixed at a position in contact with the inner surface of the riser portion inner plate 18 on the upper surface of the inclined channel top plate 17. The flow path support portion 26 is fixed to the inner surface of the riser portion outer plate 19 and extends to a position in contact with the outer surface of the riser portion inner plate 18. The lift prevention unit 27 is fixed to the upper end of the riser unit outer plate 19 and extends to a position in contact with the upper end of the riser unit inner plate 18.

  Even with such a structure, when the core melt falls, the inclined channel top plate 17 can move relative to the riser inner plate 18. That is, since the inclined flow path top plate 17 is not fixed to the riser portion inner plate 18, it becomes larger in the outer peripheral direction due to thermal expansion. Further, the flow path support portion 26 is provided at a position where it does not interfere even when the inclined flow path top plate 17 is thermally expanded.

  By supporting the cylindrical riser section inner plate 18 with the support section 25 and the flow path support section 26, the horizontal displacement between the riser section inner plate 18 and the inclined flow path top plate 17 when an earthquake occurs is prevented. Can be reduced. Further, the rise prevention unit 27 can prevent the riser inner plate 18 from being lifted when an earthquake occurs.

  In the present embodiment, the thermal stress in the cooling channel 11 can be reduced by adopting a structure that does not restrain the thermal expansion of the inclined channel top plate 17 and the riser unit inner plate 18. Thus, the possibility of damage to the core melt holding device is reduced. Furthermore, the shift | offset | difference of the riser part at the time of an earthquake can be reduced.

[Sixth Embodiment]
FIG. 9 is a perspective view of a part extracted from the sixth embodiment of the core melt holding device according to the present invention.

  In the core melt holding device of the present embodiment, a variable connection portion 28 is provided at the connection portion between the inclined flow path top plate 17 and the riser portion inner plate 18 in the first embodiment, and a load support portion 29 is further added. It is a thing. The variable connection portion 28 is, for example, a bellows. The load support portion 29 is, for example, a rod that is fixed to the inner surface of the riser portion outer plate 19 and extends inward in the radial direction. The riser section inner plate 18 is supported by a load support section 29.

  Thermal expansion when the core melts of the inclined flow path top plate 17 and the riser portion inner plate 18 fall can be absorbed by the variable connection portion 28. Moreover, since the riser part inner side board 18 is supported by the load support part 29, the shift | offset | difference of the riser part inner side board 18 and the inclination flow path top plate 17 at the time of an earthquake can be reduced.

  In the present embodiment, the thermal stress in the cooling channel 11 can be reduced by adopting a structure that does not restrain the thermal expansion of the inclined channel top plate 17 and the riser unit inner plate 18. Thus, the possibility of damage to the core melt holding device is reduced. Furthermore, the shift | offset | difference of the riser part at the time of an earthquake can be reduced. Thus, the possibility of damage to the core melt holding device is reduced.

[Seventh Embodiment]
FIG. 10 is a perspective view of a part extracted from the seventh embodiment of the core melt holding device according to the present invention.

  In the core melt holding device of the present embodiment, a deformation absorbing portion 30 is provided at the connection portion between the inclined flow path top plate 17 and the riser inner plate 18 in the first embodiment. The deformation absorbing portion 30 is obtained by folding the outer peripheral portion of the inclined channel top plate 17 inward and upward, and the folded end portion is coupled to the riser portion inner plate 18.

  Even if the inclined channel top plate 17 and the riser inner plate 18 are combined in this way, the thermal expansion when the core melt of the inclined cooling channel top plate 17 and the riser inner plate 18 falls is deformed. It is possible to absorb the absorption part 30. Further, since the inclined channel top plate 17 and the riser unit inner plate 18 are coupled via the deformation absorbing unit 30, the riser unit inner plate 18 and the inclined channel top plate 17 are displaced when an earthquake occurs. The possibility can be reduced.

  In the present embodiment, the thermal stress in the cooling channel 11 can be reduced by adopting a structure that does not restrain the thermal expansion of the inclined channel top plate 17 and the riser unit inner plate 18. Thus, the possibility of damage to the core melt holding device is reduced. Furthermore, the shift | offset | difference of the riser part at the time of an earthquake can be reduced.

[Eighth Embodiment]
FIG. 11 is a perspective view of a part extracted from the eighth embodiment of the core melt holding device according to the present invention.

  In the core melt holding device of the present embodiment, the waterproof film 31 is pasted on the cooling channel 11 side of the connecting portion 20 between the inclined channel top plate 17 and the riser inner plate 18 in the first embodiment. Is. As the waterproof film 31, heat-resistant rubber that easily deforms can be used.

  Even if the inclined channel top plate 17 and the riser unit inner plate 18 are joined by the waterproof membrane 31, if the waterproof membrane 31 is easily deformed, the core melt of the inclined channel top plate 17 and the riser unit inner plate 18 is removed. It does not constrain thermal expansion when dropped. For this reason, the thermal expansion of each of the inclined channel top plate 17 and the riser unit inner plate 18 can be absorbed by the connection unit 20, and the thermal stress in the cooling channel 11 can be reduced. Thus, the possibility of damage to the core melt holding device is reduced. Further, the waterproof film 31 can prevent leakage of the cooling water from the cooling flow path 11 to the container portion holding the core melt.

[Ninth Embodiment]
FIG. 12 is a perspective view of a part extracted from the ninth embodiment of the core melt holding device according to the present invention.

  In the core melt holding device of the present embodiment, a sealing material 32 is sandwiched between the inclined channel top plate 17 and the riser inner plate 18 in the first embodiment.

  If the sealing material 32 is easily deformed even if the sealing material 32 is sandwiched between the inclined channel top plate 17 and the riser unit inner plate 18, the core melt of the inclined channel top plate 17 and the riser unit inner plate 18 is changed. It does not constrain thermal expansion when dropped. For this reason, the thermal expansion of each of the inclined cooling channel top plate 17 and the riser unit inner plate 18 is absorbed by the connection unit 20, and the thermal stress in the cooling channel 11 can be reduced. Thus, the possibility of damage to the core melt holding device is reduced. Further, the sealing material 32 can prevent leakage of the cooling water from the cooling flow path 11 to the container portion holding the core melt.

[Tenth embodiment]
FIG. 13 is a perspective view of a part extracted from the tenth embodiment of the core melt holding device according to the present invention.

  The core melt holding device of the present embodiment is obtained by bonding the inclined flow path top plate 17 and the riser portion inner plate 18 in the first embodiment with a low melting point metal 33. As the low melting point metal 33, a metal that melts due to a temperature rise when the core melt 13 (see FIG. 3) falls into the core melt holding container is used. Instead of the low melting point metal 33, an adhesive that loses the adhesive strength at a high temperature may be used.

  Even if the inclined flow path top plate 17 and the riser portion inner plate 18 are bonded with the low melting point metal 33, if the low melting point metal 33 is melted by the temperature rise when falling to the core melt holding container, the inclined flow path top plate is reduced. The thermal expansion when the core melt of the plate 17 and the riser inner plate 18 falls is not restricted. For this reason, the thermal expansion of each of the inclined channel top plate 17 and the riser unit inner plate 18 can be absorbed by the connection unit 20, and the thermal stress in the cooling channel 11 can be reduced. Thus, the possibility of damage to the core melt holding device is reduced. Moreover, since the low melting point metal 33 does not lose its adhesive force even during an earthquake, it is possible to prevent the inclined flow path top plate 17 and the riser portion inner plate 18 from being displaced during an earthquake.

  Thus, in the present embodiment, the thermal stress in the cooling flow path 11 is reduced by adopting a structure that does not restrain the thermal expansion of the inclined flow path top plate 17 and the riser inner plate 18 when the core melt falls. In addition, it is possible to reduce the shift of the riser portion during an earthquake.

[Other embodiments]
The above description is merely an example, and the present invention is not limited to the above-described embodiments, and can be implemented in various forms. Moreover, it can also implement combining the characteristic of each embodiment.

DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel, 2 ... Containment vessel, 3 ... Lower head, 4 ... Suppression pool, 5 ... Water tank, 6 ... Containment vessel cooler, 7 ... Lower dry well, 8 ... Sump bed, 9 ... Retain core melt Apparatus: 10 ... Water supply container, 11 ... Cooling flow path, 12 ... Heat-resistant material, 13 ... Core melt, 14 ... Water injection pipe, 15 ... Water supply flow path, 16 ... Inclined flow path bottom plate, 17 ... Inclined flow path top plate, DESCRIPTION OF SYMBOLS 18 ... Riser part inner side plate, 19 ... Riser part outer side plate, 20 ... Connection part, 21 ... Flow path support, 22 ... Flow path support guide, 23 ... Granular heat resistant material, 24 ... Fibrous heat resistant material, 25 ... Support part, 26 ... Flow path support part, 27 ... Floating prevention part, 28 ... Variable connection part, 29 ... Load support part, 30 ... Deformation absorption part, 31 ... Waterproof membrane, 32 ... Seal material, 33 ... Low melting point metal, 40 ... Valve, 41 ... pedestal floor, 42 ... pedestal sidewall, 43 ... core, 51 Cooling channel member, 61 ... inclined portion heat-resistant material, 62 ... riser heat-resistant material

Claims (9)

In the core melt holding device for holding the core melt generated when the core stored in the reactor pressure vessel melts and falls,
A water supply vessel provided below the reactor pressure vessel and supplied with cooling water;
A top plate that spreads radially from the water supply container and a cylindrical riser portion that is provided so as to be movable relative to the top plate when the core melt falls and rises from the outer periphery of the top plate A cooling flow path extending from the water supply container through an inclined portion that is in contact with the lower surface of the top plate and a riser portion that is connected to the inclined portion and is in contact with the outer surface of the inner plate of the riser portion. A cooling flow path forming body,
A core melt holding device characterized by comprising: An inclined portion heat-resistant material laid on the upper surface of the top plate;
A riser portion heat-resistant material laid on the inner surface of the riser portion inner plate;
Either granular or fibrous heat resistant material laid between the inclined heat resistant material and the riser heat resistant material;
The core melt holding device according to claim 1, comprising:   3. The core melt holding device according to claim 1, wherein the riser inner plate is located inside an outer edge of the top plate. 4. A support portion that protrudes upward from the top surface of the top plate at a position closer to the water supply container than the riser portion inner plate;
A flow path support portion protruding from the riser portion outer plate toward the riser portion inner plate,
A floating prevention unit fixed to the riser unit outer plate and pressing the upper side of the riser unit inner plate;
The core melt holding device according to any one of claims 1 to 3, characterized by comprising:   The core melt holding device according to any one of claims 1 to 4, wherein the top plate and the riser portion inner plate are connected via a deformable connecting portion.   The core melt holding device according to any one of claims 1 to 4, further comprising a waterproof film that covers a boundary portion between the top plate and the riser portion inner plate.   5. The core melt holding device according to claim 1, further comprising a sealing material sandwiched between boundaries of the top plate and the riser unit inner plate. 6.   The boundary between the top plate and the inner plate of the riser unit is joined by either a low melting point metal that melts when heated by the core melt or an adhesive that loses adhesive strength when heated by the core melt. The core melt holding device according to any one of claims 1 to 4, wherein the core melt holding device is provided. In the containment vessel that stores the reactor pressure vessel containing the reactor core,
With a pedestal floor,
A pedestal sidewall that surrounds the pedestal floor and extends vertically upward to support the reactor pressure vessel;
A water supply container provided on the pedestal floor and supplied with cooling water;
A top plate that spreads radially from the water supply container and a cylindrical riser portion that is provided so as to be movable relative to the top plate when the core melt falls and rises from the outer periphery of the top plate A cooling flow path extending from the water supply container through an inclined portion that is in contact with the lower surface of the top plate and a riser portion that is connected to the inclined portion and is in contact with the outer surface of the inner plate of the riser portion. A cooling flow path forming body,
A containment vessel.

Images