JP2019045339A - Corium holding structure and reactor container - Google Patents

Abstract

To prevent damage of a structure caused by corium.SOLUTION: A corium holding structure includes a sacrifice material 1 provided between a reactor vessel 41 and a floor part 150a for receiving corium under the reactor vessel 41, for lowering a melting point of the corium by being melted and mixed with the corium, to thereby lower viscosity thereof.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a core melt holding structure and a reactor containment vessel.

  In a nuclear power plant, an accident in which core melt flows out of a reactor vessel is assumed as a severe accident. When the core melt falls into the cavity chamber of the reactor containment vessel, the damage may be magnified if serious damage occurs in the structure forming the cavity chamber. Therefore, it is necessary to take measures so as to suppress the occurrence of serious damage to the reactor containment vessel.

  Conventionally, for example, in Patent Document 1, a structure having a bottom portion and a wall portion that form a cavity chamber is provided below the reactor vessel, and the wall portion includes a wall iron plate facing the cavity chamber and a cavity chamber. On the other hand, there is shown a reactor containment vessel having wall concrete provided outside the wall iron plate and a wall liner provided outside the wall concrete with respect to the cavity chamber.

  Conventionally, for example, in Patent Document 2, there is a core melt holding device that receives and holds a core melt below a reactor vessel in the event of a core melt accident of a nuclear reactor. A plurality of core melt holding blocks that are arranged so as to form an inclined bottom surface in which a through hole through which a coolant can flow is formed, and a support base that supports the core melt holding block The through holes formed in the plurality of core melt holding blocks are in communication with each other, and the coolant introduction part that introduces the coolant into the through holes discharges the coolant from the through holes. A core melt holding device is shown which is arranged at a position lower than the part and arranged so that the height position of the through hole gradually increases from the coolant introduction part toward the coolant discharge part. .

Japanese Patent Laid-Open No. 2006-166833 Japanese Patent Laid-Open No. 2014-081212

  In the reactor containment vessel disclosed in Patent Document 1 described above, the core melt that has flowed out of the reactor vessel is received by a cavity chamber provided below the reactor vessel, and dammed by a wall portion of the structure. Further, in the core melt holding device disclosed in Patent Document 2 described above, when the core melt falls onto the core melt holding block, the upper surface portion of the core melt holding block that holds the core melt is melted into the core. The core melt is cooled by absorbing heat from the object and radiating heat to the side surface and the bottom surface. Thus, conventionally, the core melt is dammed or cooled at the place where it falls.

  However, if the core melt is dammed or cooled in the place where it falls, it may stay thick without spreading in the place where the core melt falls, that is, in a limited area. When the core melt continues to fall, it rises and is held in a limited area, and the internal cooling of the lower part is delayed, so that the erosion rate to the structure (such as floor concrete) forming the cavity chamber is high. There is concern that the structure will melt and damage will occur.

  The present invention solves the above-described problems, and an object thereof is to provide a core melt holding structure and a reactor containment vessel that can prevent damage to the structure due to the core melt.

  A core melt holding device according to an aspect of the present invention is provided between a nuclear reactor vessel and a floor portion that receives the core melt below the nuclear reactor vessel, and melts and mixes with the core melt. A sacrificial material that lowers the melting point of the core melt to lower the viscosity is provided.

  In the core melt holding device according to one aspect of the present invention, it is preferable that the sacrificial material includes one or more of an iron compound, an alkali compound, a silicate compound, calcium silicate, and alumina.

  In the core melt holding device according to one aspect of the present invention, it is desirable that the sacrificial material has a mass of 10% or more with respect to the mass of the core melt.

  In the core melt holding device according to one aspect of the present invention, it is preferable that the sacrificial material is configured in a layered manner in the upper and lower directions, and the lower layer is configured with a material having a low viscosity reducing effect with respect to the upper layer.

  In the core melt holding device according to one aspect of the present invention, it is desirable that the sacrificial material includes a reducing material that reduces the main composition of the core melt.

  In the core melt holding device according to one aspect of the present invention, it is desirable that the sacrificial material includes a coolant that cools the main composition of the core melt.

  A reactor containment vessel according to an aspect of the present invention includes a reactor vessel, a floor portion provided below the reactor vessel for receiving a core melt, and a core melt holding device according to any one of the above And a structure.

  According to the present invention, the sacrificial material is melted and mixed with the core melt that has flowed out of the reactor vessel, thereby lowering the melting point of the core melt and lowering the viscosity. The core melt whose viscosity has been reduced flows along the floor and spreads thinly, and is sufficiently cooled in the thickness direction. For this reason, it is possible to prevent the core melt from staying thick on the floor, or to suppress the erosion of the floor even if the core melt reaches the floor. As a result, it is possible to prevent the floor portion from being eroded and to prevent damage to the structure due to the core melt.

FIG. 1 is a schematic configuration diagram illustrating an example of a nuclear power plant to which a nuclear reactor containment vessel according to an embodiment of the present invention is applied. FIG. 2 is a cross-sectional view showing a reactor structure of a pressurized water reactor applied to a reactor containment vessel according to an embodiment of the present invention. FIG. 3 is a schematic configuration diagram illustrating an example of a nuclear reactor containment vessel according to an embodiment of the present invention. FIG. 4 is a side sectional view of the core melt holding structure according to Embodiment 1 of the present invention. FIG. 5 is a side sectional view showing the operation of the core melt holding structure according to the first embodiment of the present invention. FIG. 6 is a side sectional view of another example of the core melt holding structure according to Embodiment 1 of the present invention. FIG. 7 is a perspective view of the sacrificial material of the core melt holding structure according to Embodiment 2 of the present invention. FIG. 8 is a plan view of the sacrificial material of the core melt holding structure according to Embodiment 2 of the present invention. FIG. 9 is a side sectional view of the core melt holding structure according to Embodiment 3 of the present invention. FIG. 10 is a side sectional view of the core melt holding structure according to Embodiment 4 of the present invention. FIG. 11 is a side sectional view of a core melt holding structure according to Embodiment 5 of the present invention. FIG. 12 is a side sectional view of a core melt holding structure according to Embodiment 6 of the present invention. FIG. 13 is a side sectional view of a core melt holding structure according to Embodiment 7 of the present invention. FIG. 14 is a side sectional view showing the operation of the core melt holding structure according to the seventh embodiment of the present invention. FIG. 15 is a side sectional view showing the operation of the core melt holding structure according to the seventh embodiment of the present invention. FIG. 16 is a side sectional view of a core melt holding structure according to Embodiment 8 of the present invention. FIG. 17 is a side sectional view of another example of the core melt holding structure according to Embodiment 8 of the present invention. FIG. 18 is a side sectional view of a core melt holding structure according to Embodiment 9 of the present invention. FIG. 19 is a side sectional view of a core melt holding structure according to Embodiment 10 of the present invention. FIG. 20 is a side sectional view showing the operation of the core melt holding structure according to the tenth embodiment of the present invention. FIG. 21 is a side sectional view of a core melt holding structure according to Embodiment 11 of the present invention. FIG. 22 is a side sectional view showing the operation of the core melt holding structure according to the eleventh embodiment of the present invention. FIG. 23 is a side sectional view of a core melt holding structure according to Embodiment 12 of the present invention. FIG. 24 is a side sectional view of another example of the core melt holding structure according to Embodiment 12 of the present invention. FIG. 25 is a side sectional view of the core melt holding structure according to the thirteenth embodiment of the present invention. FIG. 26 is a side sectional view of a sacrificial material for a core melt holding structure according to Embodiment 13 of the present invention.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  FIG. 1 is a schematic configuration diagram illustrating an example of a nuclear power plant to which a nuclear reactor containment vessel according to the present embodiment is applied. FIG. 2 is a cross-sectional view showing a reactor structure of a pressurized water reactor applied to the reactor containment vessel according to the present embodiment. FIG. 3 is a schematic configuration diagram illustrating an example of a nuclear reactor containment vessel according to the present embodiment.

  The nuclear reactor applied to the nuclear power plant of the present embodiment uses light water as a reactor coolant and a neutron moderator to produce high-temperature and high-pressure water that does not boil over the entire primary system, and sends this high-temperature and high-pressure water to a steam generator. This is a pressurized water reactor (PWR) that generates steam by heat exchange and sends the steam to a turbine generator to generate electricity.

  In the nuclear power plant having this pressurized water reactor, as shown in FIG. 1, the reactor containment vessel 11 stores therein a pressurized water reactor 12 and a steam generator 13. The pressurized water reactor 12 and the steam generator 13 are connected via cooling water pipes 14 and 15. The cooling water pipe 14 is provided with a pressurizer 16. The cooling water pipe 15 is provided with a primary coolant circulation pump 17. Accordingly, in the pressurized water reactor 12, light water is heated as a primary coolant by the fuel constituting the core, and the steam generator 13 is passed through the cooling water pipe 14 in a state where the high temperature light water is maintained at a predetermined high pressure by the pressurizer 16. Sent to. In the steam generator 13, heat exchange is performed between the high-temperature and high-pressure light water (primary coolant) and the secondary coolant, and the cooled light water is supplied to the pressurized water type through the cooling water pipe 15 by the primary coolant circulation pump 17. Returned to reactor 12.

  The steam generator 13 is connected to a steam turbine 18 and a condenser 19 provided outside the reactor containment vessel 11 via cooling water pipes 20 and 21. The cooling water pipe 21 is provided with a water supply pump 22. The steam turbine 18 is connected to a generator 23. The condenser 19 is connected to a water intake pipe 24 and a drain pipe 25 that supply and discharge cooling water (for example, seawater). Accordingly, the steam generated by exchanging heat with the high-pressure and high-temperature primary cooling water in the steam generator 13 is sent to the steam turbine 18 through the cooling water pipe 20, and the steam turbine 18 is driven by this steam to generate power. Electric power is generated by the machine 23. The steam that has driven the steam turbine 18 is cooled by the condenser 19 and then returned to the steam generator 13 through the cooling water pipe 21.

  Further, in the pressurized water reactor 12, as shown in FIG. 2, a reactor vessel 41 has a reactor vessel body 42 and a reactor vessel mounted on the reactor vessel main body 42 so that a reactor internal structure can be inserted therein. A lid (upper mirror) 43 is used. A reactor vessel lid 43 is fixed to the reactor vessel body 42 by a plurality of stud bolts 44 and nuts 45 so as to be opened and closed.

  The reactor vessel main body 42 has a cylindrical shape in which the upper portion can be opened by removing the reactor vessel lid 43 and the lower portion is closed by a lower mirror 46 having a spherical shape. The reactor vessel main body 42 is formed with an inlet nozzle (inlet nozzle) 47 for supplying light water (coolant) as primary cooling water and an outlet nozzle (exit nozzle) 48 for discharging light water. In addition to the inlet nozzle 47 and the outlet nozzle 48, the reactor vessel main body 42 is formed with a water injection nozzle (water injection pipe stand) (not shown).

  The reactor vessel main body 42 has a reactor internal structure inserted therein. The in-furnace structure will be described. An upper core support plate 49 is fixed above the inlet nozzle 47 and the outlet nozzle 48, while a lower core support plate 50 is fixed near the lower mirror 46 below. The upper core support plate 49 and the lower core support plate 50 have a disk shape and are formed with a number of communication holes (not shown). The upper core support plate 49 is connected to an upper core plate 52 formed with a plurality of communication holes (not shown) below via a plurality of core support rods 51.

  A cylindrical reactor core 53 having a cylindrical shape is disposed with a predetermined gap from the inner wall surface of the reactor vessel main body 42. An upper core plate 52 is connected to the upper part of the core tank 53, and a lower core plate 54 having a disk shape and a large number of communication holes (not shown) is connected to the lower part. The lower core plate 54 is supported by the lower core support plate 50.

  A core 55 is formed by the upper core plate 52, the core bath 53, and the lower core plate 54. A large number of fuel assemblies 56 are arranged inside the core 55. Although not shown, the fuel assembly 56 is configured by bundling a large number of fuel rods in a lattice pattern by a support lattice, and an upper nozzle is fixed to the upper end portion, while a lower nozzle is fixed to the lower end portion. The core 55 has a large number of control rods 57 disposed therein. A large number of control rods 57 are combined at the upper ends into a control rod cluster 58 that can be inserted into the fuel assembly 56. The upper core support plate 49 penetrates through the upper core support plate 49 itself, and a number of control rod cluster guide tubes 59 are fixed. Each control rod cluster guide tube 59 has a lower end extending to the control rod cluster 58 in the fuel assembly 56.

  The reactor vessel lid 43 constituting the reactor vessel 41 is provided with a control jack drive device 60 of a magnetic jack on the top. The control jack driving device 60 of the magnetic jack is accommodated in a housing 61 that is integrated with the reactor vessel lid 43. The upper ends of the control rod cluster guide tubes 59 described above are extended to the control rod driving device 60. The control rod cluster drive shaft 62 extended from the control rod drive device 60 extends to the fuel assembly 56 through the control rod cluster guide tube 59 so that the control rod cluster 58 can be gripped.

  The control rod drive device 60 extends in the vertical direction and is connected to the control rod cluster 58, and a control rod cluster drive shaft 62 having a plurality of circumferential grooves arranged at equal pitches in the longitudinal direction on the surface thereof is magnetically connected. The output of the reactor is controlled by moving it up and down with a jack.

  The reactor vessel main body 42 is provided with a number of instrumentation nozzles 63 that penetrate the lower mirror 46. In each instrumentation nozzle 63, an in-furnace instrumentation guide pipe 64 is fixed to an upper end portion inside the furnace, and a conduit tube 65 is connected to a lower end portion outside the furnace. Each in-core instrumentation guide tube 64 has an upper end connected to the lower core support plate 50. Each in-core instrumentation guide pipe 64 is provided with upper and lower connecting plates 66 and 67 for suppressing vibration. A thimble tube 68 passing from the conduit tube 65 through the instrumentation nozzle 63 and the in-core instrumentation guide tube 64 can be inserted into the fuel assembly 56 through the lower core plate 54. The thimble tube 68 is equipped with a neutron flux detector (not shown) capable of measuring the neutron flux.

  Accordingly, the control rod cluster drive shaft 62 is moved by the control rod drive device 60 and the control rod 57 is inserted into the fuel assembly 56, thereby controlling the nuclear fission in the reactor core 55 and the generated thermal energy to the reactor vessel. The light water filled in 41 is heated, and high-temperature light water is discharged from the outlet nozzle 48 and sent to the steam generator 13 as described above. That is, the nuclear fuel constituting the fuel assembly 56 is fissioned to release neutrons, and the light water as the moderator and the primary cooling water reduces the kinetic energy of the released fast neutrons to become thermal neutrons, and new It is easy to cause nuclear fission and takes away the generated heat to cool. Further, by inserting the control rod 57 into the fuel assembly 56, the number of neutrons generated in the core 55 is adjusted, and the control rod 57 is rapidly inserted into the core 55 when the reactor is urgently stopped.

  In the reactor vessel 41, an upper plenum 69 communicating with the outlet nozzle 48 is formed above the core 55, while a lower plenum 70 is formed below. A downcomer portion 71 communicating with the inlet nozzle 47 and the lower plenum 70 is formed between the nuclear reactor vessel 41 and the reactor core 53. Accordingly, the light water flows into the reactor vessel main body 42 from the inlet nozzle 47, flows down the downcomer portion 71 and reaches the lower plenum 70, and is guided upward by the spherical inner surface of the lower plenum 70. Then, after passing through the lower core support plate 50 and the lower core plate 54, it flows into the core 55. The light water that has flowed into the core 55 absorbs heat energy generated from the fuel assemblies 56 constituting the core 55 to cool the fuel assemblies 56, while at the same time passing through the upper core plate 52 at a high temperature. It rises to the upper plenum 69 and is discharged through the outlet nozzle 48.

  As shown in FIG. 3, the nuclear reactor power plant containment vessel 11 described above is erected on a solid ground 81 such as a rock, and a plurality of compartments such as an upper compartment 83 and steam are generated inside by reinforced concrete or the like. A vessel loop chamber 84 is defined. A cylindrical structure 100 that defines a steam generator loop chamber 84 is formed in the central portion of the reactor containment vessel 11, and the reactor vessel 41 is suspended by the structure 100 including the concrete. It is supported. The steam generator 13 is disposed in the steam generator loop chamber 84 and is connected by cooling water pipes 14 and 15.

  Further, the reactor containment vessel 11 is located below the reactor vessel 41 by the structure 100 and has a cavity chamber 150 defined therein. The reactor containment vessel 11 is provided with a fuel replacement water pit 88. The fuel replacement water pit 88 is cooled by supplying cooling water to the pressurized water reactor 12 and cooling the reactor water in the reactor cooling passage (cooling water supply device) 89 and cooling water to the reactor containment vessel 11 in an emergency. A reactor containment vessel cooling path (cooling water supply device) 90 is connected. The cooling water sprayed in the reactor containment vessel 11 is stored in the cavity chamber 150 from the steam generator loop chamber 84 via a drain line (not shown) provided in the structure 100.

  Although not shown, the reactor containment vessel 11 is provided with an external injection path such as fire water for supplying cooling water to the cavity chamber 150. The external injection path has a base end connected to an external supply facility such as fire extinguishing water installed outside the reactor containment vessel 11, and a distal end communicating with the cavity chamber 150.

  Thus, in the reactor containment vessel 11, the cavity chamber 150 capable of supplying cooling water is provided below the reactor vessel 41 of the pressurized water reactor 12.

  Hereinafter, embodiments of the core melt holding structure will be described.

[Embodiment 1]
FIG. 4 is a side sectional view of the core melt holding structure according to the first embodiment. FIG. 5 is a side sectional view showing the operation of the core melt holding structure according to the first embodiment. FIG. 6 is a side sectional view of another example of the core melt holding structure according to the first embodiment.

  As shown in FIG. 4, the core melt holding structure of Embodiment 1 includes a sacrificial material 1 provided between a reactor vessel 41 and a floor 150 a of a cavity chamber 150 below the reactor vessel 41. Prepare. In FIG. 4, the form which has arrange | positioned the sacrificial material 1 on the upper surface of the floor part 150a is shown.

  When the lower part of the reactor vessel 41 (reactor vessel body 42) is damaged by the severe accident accompanied by the melting of the core and the core melt 10 flows out of the reactor vessel 41, it flows out of the lower portion of the reactor vessel 41. The core melt 10 thus dropped falls toward the floor 150a of the cavity chamber 150 of the reactor containment vessel 11 provided below the reactor vessel 41 (see FIG. 5). That is, the floor 150 a of the cavity chamber 150 receives the core melt 10. The core melt 10 includes a melted core and a core structure melted along with the melted core.

  The sacrificial material 1 is melt-mixed with the core melt 10, thereby lowering the melting point of the core melt 10 to lower the viscosity. For this reason, the core melt 10 having a reduced viscosity flows along the floor 150a of the cavity chamber 150, spreads thinly, and is sufficiently cooled in the thickness direction. Therefore, it can suppress that the core melt 10 stays thick on the floor 150a. As a result, the situation where the floor 150a of the cavity chamber 150 made of concrete is eroded can be prevented, and damage to the structure 100 due to the core melt 10 can be prevented.

The sacrificial material 1 contains one or two or more compositions of iron compound, alkali compound, silicate compound, calcium silicate (CaCiO ₃ ), and alumina (Al ₂ O ₃ ). Examples of the iron compound include carbon steel, stainless steel, Fe ₂ O ₃ , Fe ₃ O ₄ , and iron ore. Examples of the alkali compound include calcium-based Ca, CaO, Ca (OH) ₂ , CaCO ₃ , limestone, magnesium-based Mg, MgO, Mg (OH) ₂ , MgCO ₃ , dolomite, and the like. Na, Na ₂ O, NaOH, NaHCO ₃ , Na ₂ CO ₃ , baking soda, trona, etc. The silicate compounds, for example, SiO ₂ or sand and, and stone, and calcium silicate, and the like magnesium silicate.

The core melt 10 and the sacrificial material 1 come into contact and react to form a mixture, which reduces the melting point. The main composition of the core melt 10 is UO ₂ and ZrO ₂ , which have relatively high melting points and tend to increase in viscosity and harden as the temperature decreases. For example, although the melting point of ZrO ₂ is about 3000K, it decreases to about 1600K when mixed with iron or calcium silicate, and decreases to about 2500K when mixed with calcium oxide (CaO). The core melt 10 having a lowered melting point is reduced in viscosity, and exhibits the above-described effects.

Here, since the order of increasing the effect of lowering the melting point and lowering the viscosity is Fe, CaCiO ₃ > CaO, MgO> SiO ₂ > Al ₂ O ₃ > UO ₂ , ZrO ₂ , the sacrificial material 1 has a low viscosity. It is desirable to include a lot of compositions that have a large effect, and the above effects can be obtained remarkably. The order of such composition is the document Sun Yong Kwon, “Thermodynamic Optimization of ZrO2-Containing Systems in the CaO-MgO-SiO2-Al2O3-ZrO2 system.” (Http://digitool.library.mcgill.ca/webclient/DeliveryManager? pid = 135720) can be used as a basis.

  Further, the larger the ratio of the sacrificial material 1 to the core melt 10, the greater the effect of lowering the melting point and lowering the viscosity, and the core melt 10: sacrificial material 1 satisfies at least 2: 1 in molar ratio. It is desirable. And it is desirable for the sacrificial material 1 to have a mass of 10% or more with respect to the assumed mass of the core melt 10 in order to obtain the above-mentioned effects remarkably.

  Further, the sacrificial material 1 may be disposed at least under the reactor vessel 41. However, the sacrificial material 1 is mixed with the core melt 10 extending from the lower side of the reactor vessel 41 to the outer region to lower the viscosity. As shown in FIG. 4 and FIG. 5, it is desirable that the reactor vessel 41 is also disposed in a region outside the region below the reactor vessel 41.

  In the form shown in FIG. 6, the sacrificial material 1 is configured in a layered manner in the vertical direction, and in the figure, it is configured by an upper layer sacrificial material 1a and a lower layer sacrificial material 1b. In this configuration, it is desirable that the lower layer sacrificial material 1b is made of a material having a low viscosity reducing effect with respect to the upper layer sacrificial material 1a. Reducing the viscosity can be achieved by following the order in which the effect of lowering the melting point and lowering the viscosity is large, or by changing the mass of the same composition that lowers the melting point and lowers the viscosity.

  Note that the number of layers is not limited to the above two layers, but the sacrificial material 1 may be configured in a layered manner in the upper and lower layers, and the lower layer may be configured with a material having a low lowering effect relative to the upper layer. Further, it is included that each layer is not strictly divided and is configured to have a composition having a gradually lowering viscosity effect downward.

  Therefore, after the core melt 10 whose viscosity has been lowered in the upper layer spreads along the floor 150a, the lowering effect in the lower layer is lowered, that is, the viscosity is increased, and the erosion rate (fluidity) is lowered. For this reason, the core melt 10 can be held while suppressing the core melt 10 spreading along the floor 150a from staying thick on the floor 150a. As a result, the situation where the floor 150a of the cavity chamber 150 made of concrete is eroded can be prevented, and damage to the structure 100 due to the core melt 10 can be prevented. Note that by increasing the eutectic temperature, viscosity and melting point can be increased even if the temperature does not decrease, and a material for increasing the eutectic temperature may be provided in the lower layer.

By the way, the sacrificial material 1 is not limited to the said composition. For example, the sacrificial material 1 may include a reducing material that reduces the main composition of the core melt 10. Examples of the reducing material include carbon (such as coke), hydrogen, and sodium sulfite. Specifically, the main composition ZrO ₂ of the core melt 10 is reduced to CO ₂ and Zr by carbon C. As described above, the sacrificial material 1 including the reducing material can lower the melting point of the core melt 10 to lower the viscosity. For this reason, the core melt 10 having a reduced viscosity flows along the floor 150a of the cavity chamber 150, spreads thinly, and is sufficiently cooled in the thickness direction. Therefore, it can suppress that the core melt 10 stays thick on the floor 150a. As a result, the situation where the floor 150a of the cavity chamber 150 made of concrete is eroded can be prevented, and damage to the structure 100 due to the core melt 10 can be prevented.

The sacrificial material 1 is not limited to the above composition. For example, the sacrificial material 1 may include a coolant that cools the main composition of the core melt 10. The coolant includes, for example, a material containing crystal water and includes, for example, MgCl ₂ .6H ₂ O, Na ₂ SO ₄ .10H ₂ O, CaSO ₄ .2H ₂ O, and the like. As described above, the sacrificial material 1 containing crystallization water as a coolant can be cooled by the latent heat of evaporation taken away when the crystallization water is evaporated to lower the melting point of the core melt 10 and reduce the viscosity. For this reason, the core melt 10 having a reduced viscosity flows along the floor 150a of the cavity chamber 150, spreads thinly, and is sufficiently cooled in the thickness direction. Therefore, it can suppress that the core melt 10 stays thick on the floor 150a. As a result, the situation where the floor 150a of the cavity chamber 150 made of concrete is eroded can be prevented, and damage to the structure 100 due to the core melt 10 can be prevented.

[Embodiment 2]
FIG. 7 is a perspective view of the sacrificial material of the core melt holding structure according to the second embodiment. FIG. 8 is a plan view of the sacrificial material of the core melt holding structure according to the second embodiment.

  The core melt holding structure of the second embodiment is characterized by the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIGS. 7 and 8, the sacrificial material 1A is formed in a plurality of blocks, and the blocks are provided side by side on the upper surface of the floor 150a. 7 and 8 show an example in which the sacrificial material 1A is formed in a regular triangular prism, but may be a polygonal prism such as a quadrangular prism, a regular quadrangular prism, a regular pentagonal prism, or a regular hexagonal prism. Any shape that is provided side by side on the upper surface of the floor 150a may be used. Further, the sacrificial material 1A is provided with a hanging tool 1Aa such as an eyebolt on the upper surface thereof. One block-shaped sacrificial material 1A is designed to be, for example, several kilograms to several tens of kilograms, and can be installed or removed by being suspended with a crane or the like by the suspension tool 1Aa.

  As described above, in the core melt holding structure according to the second embodiment, the sacrificial material 1A is formed in a plurality of blocks, so that each mass is reduced and portability is improved. For this reason, installation can be performed easily. Further, in the core melt holding structure of the second embodiment, the sacrificial material 1A can be transported, installed, or removed by being suspended by a crane or the like using the hanging tool 1Aa. Therefore, according to the core melt holding structure of the second embodiment, it is possible to easily remove or re-install the structure 100 (the floor 150a of the cavity chamber 150) during periodic inspection.

  Although not explicitly shown in the drawing, in the core melt holding structure of the first embodiment, the sacrificial material 1A may be configured such that the sacrificial materials 1A that are arranged on the upper surface of the floor portion 150a are fitted to each other by unevenness. By doing in this way, the mutual position shift when arrange | positioning can be suppressed.

[Embodiment 3]
FIG. 9 is a side sectional view of the core melt holding structure according to the third embodiment.

  The core melt holding structure of the third embodiment is characterized by the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 9, the sacrificial material 1B is formed into a plurality of grains, and the grains are provided on the upper surface of the floor 150a. Although FIG. 9 shows an example in which the sacrificial material 1B is formed in a spherical granular shape, the shape is not limited. One granular sacrificial material 1B is designed to be several g to several tens of g, for example, and a plurality of the sacrificial materials 1B are accommodated in a container such as a bag and can be carried and installed or removed. Granular includes powdery.

  As described above, in the core melt holding structure according to the third embodiment, the sacrificial material 1B is formed in a plurality of grains, so that the mass is reduced and the portability is improved. For this reason, installation can be performed easily. Therefore, according to the core melt holding structure of the third embodiment, it is possible to easily remove or re-install the structure 100 (the floor 150a of the cavity chamber 150) during periodic inspection. In addition, in the core melt holding structure of the third embodiment, the core melt can be installed in complicated shapes, uneven portions, and gaps, regardless of the shape of the floor 150a to be spread, and the degree of freedom of installation can be improved.

  In the core melt holding structure of the third embodiment, it is desirable that the granular sacrificial material 1B is accommodated in a plurality of containers (for example, bags) having a melting point lower than that of the core melt 10. For this reason, it can be transported and installed or removed easily. Further, by installing the container as it is, the container can be melted by the core melt 10 and the sacrificial material 1B can be mixed with the core melt 10. Further, the container may be configured as a sacrificial material.

[Embodiment 4]
FIG. 10 is a side sectional view of the core melt holding structure according to the fourth embodiment.

  The core melt holding structure of the fourth embodiment is characterized by the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 10, the sacrificial material 1C is formed in layers, and the layers are provided on the upper surface of the floor 150a. The layer shape includes a film shape, a film shape, a sheet shape, a tile shape, a panel shape, and the like. Further, the layered sacrificial material 1C has flexibility and is wound around a roll shape to be transported and installed or removed. The layered sacrificial material 1C is designed to have a thickness of, for example, several mm to several tens of mm, and a plurality of the sacrificial materials 1C can be installed.

  As described above, in the core melt holding structure according to the fourth embodiment, the sacrificial material 1C is formed in a layered manner, so that individual masses are reduced and portability is improved. For this reason, installation can be performed easily. Therefore, according to the core melt holding structure of the fourth embodiment, it is possible to easily remove or re-install the structure 100 (the floor 150a of the cavity chamber 150) during periodic inspection.

[Embodiment 5]
FIG. 11 is a side sectional view of the core melt holding structure according to the fifth embodiment.

  The core melt holding structure of the fifth embodiment is characterized by the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 11, the sacrificial material 1D is formed in a linear shape, and the linear shape is provided on the upper surface of the floor 150a. The linear shape includes a fiber shape, a string shape, a rope shape, and the like. Further, the linear sacrificial material 1D is flexible and can be wound and transported in a ring shape to be installed or removed. The linear sacrificial material 1D is designed to have a diameter of, for example, several mm to several tens of mm, and can be installed by being entangled, bent, or wound.

  As described above, in the core melt holding structure of the fifth embodiment, since the sacrificial material 1D is formed in a linear shape, the individual mass is reduced and the portability is improved. For this reason, installation can be performed easily. Therefore, according to the core melt holding structure of the fifth embodiment, the periodic removal of the structure 100 (the floor 150a of the cavity chamber 150) and the re-installation can be easily performed. Further, in the core melt holding structure of the fifth embodiment, it can be installed in a complicated shape, uneven portion or gap, regardless of the shape of the floor portion 150a to be spread, and the degree of freedom of installation can be improved.

[Embodiment 6]
FIG. 12 is a side sectional view of the core melt holding structure according to the sixth embodiment.

  The core melt holding structure of the sixth embodiment is characterized by the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 12, the sacrificial material 1E is formed in a plurality of blocks, and the blocks are provided so as to be arranged or overlapped on the upper surface of the floor 150a. The sacrificial material 1E is provided with a hanging tool 1Ea such as an eyebolt on the upper surface thereof. One block-shaped sacrificial material 1E is designed to be, for example, several kilograms to several tens of kilograms, and can be installed or removed by being suspended by a crane or the like with the suspension tool 1Ea. Further, the sacrificial material 1E has a recess 1Eb in the lower part so as to avoid interference with the suspending tool 1Ea of the lower sacrificial material 1E when being stacked up and down.

  As described above, in the core melt holding structure of the sixth embodiment, the sacrificial material 1E is formed in a plurality of blocks, so that the mass is reduced and the portability is improved. For this reason, installation can be performed easily. Further, in the core melt holding structure of the sixth embodiment, the sacrificial material 1E can be transported, installed, or removed by being hung with a crane or the like by the hanger 1Ea. Therefore, according to the core melt holding structure of the sixth embodiment, the periodic removal of the structure 100 (the floor 150a of the cavity chamber 150) and the re-installation can be easily performed. Further, in the core melt holding structure of the sixth embodiment, the sacrificial material 1E is provided with a recess 1Eb that avoids the lower hanging tool 1Ea, and even when stacked up and down, mutual interference can be prevented.

[Embodiment 7]
FIG. 13 is a side sectional view of the core melt holding structure according to the seventh embodiment. FIG. 14 is a side sectional view showing the operation of the core melt holding structure according to the seventh embodiment. FIG. 15 is a side sectional view showing the operation of the core melt holding structure according to the seventh embodiment.

  The core melt holding structure of the seventh embodiment is characterized by the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 13, the sacrificial material 1 </ b> F is disposed on the upper surface of the floor 150 a that is a region below the reactor vessel 41. The form of the sacrificial material 1F includes the forms shown in the above-described Embodiments 2 to 6. Further, the sacrificial material 1F is not disposed on the upper surface of the floor 150a, which is a region outside the region below the reactor vessel 41 around the sacrificial material 1F. Although the region where the sacrificial material 1F is disposed is defined below the reactor vessel 41, this region includes at least the region immediately below the reactor vessel 41. The region immediately below the reactor vessel 41 is followed by the reactor. The area | region which remove | deviates from directly under the container 41 may be included. That is, in the core melt holding structure of the seventh embodiment, there is a region where the floor 150a is exposed around the region where the sacrificial material 1F is disposed.

  As described above, in the core melt holding structure according to the seventh embodiment, the region where the sacrificial material 1F is not disposed is provided around the region where the sacrificial material 1F is disposed. Accordingly, the core melt 10 is reduced in viscosity by the sacrificial material 1F and spreads along the floor 150a, and then reaches a region where the sacrificial material 1F is not disposed while being cooled in a spread state. When reaching the region where the sacrificial material 1F is not disposed, the core melt 10 spreads, so that it is easy to cool and the erosion to the floor 150a is suppressed. As a result, the situation where the floor 150a of the cavity chamber 150 made of concrete is eroded can be prevented, and damage to the structure 100 due to the core melt 10 can be prevented. Moreover, since there is a region where the sacrificial material 1F is not disposed, the inspection can be performed without removing or re-installing the sacrificial material 1F during the periodic inspection of the structure 100 (the floor 150a of the cavity chamber 150).

  Further, in the core melt holding structure of the seventh embodiment, as shown in FIG. 13, the weir 2 is arranged on the upper surface of the floor portion 150a so as to surround the sacrificial material 1F. The weir 2 is made of a material having a melting point lower than that of the melt in which the core melt 10 and the sacrificial material 1F are mixed. The weir 2 may contain the composition of the sacrificial material 1 shown in the first embodiment.

  Accordingly, as shown in FIG. 14, the core melt 10 is stored by the weir 2 while being reduced in viscosity by the sacrificial material 1F, so that the melt mixing with the sacrificial material 1F is promoted and the reduction in viscosity is improved. To do. Thereafter, as shown in FIG. 15, since the weir 2 is melted by the melt in which the core melt 10 and the sacrificial material 1F are mixed, the core melt 10 having a reduced viscosity spreads and spreads along the floor 150a. It reaches the region where the sacrificial material 1F is not disposed while being cooled in a heated state. When reaching the region where the sacrificial material 1F is not disposed, the core melt 10 spreads, so that it is easy to cool and the erosion to the floor 150a is suppressed. By arranging the weir 2 in this way, it is possible to promote the melt mixing of the core melt 10 with the sacrificial material 1F and improve the viscosity reduction. As a result, the situation where the floor 150a of the cavity chamber 150 made of concrete is eroded can be prevented, and damage to the structure 100 due to the core melt 10 can be prevented.

  In addition, as shown in FIGS. 13-15, in the area | region which does not arrange | position the sacrificial material 1F, the inclined surface 150b which becomes a downward inclination as it leaves | separates from the area | region which arrange | positioned the sacrificial material 1F is formed in the floor part 150a. Is desirable. For this reason, the core melt 10 is easy to spread along the inclined surface 150b, and the cooling performance of the core melt 10 can be improved.

[Embodiment 8]
FIG. 16 is a side sectional view of the core melt holding structure according to the eighth embodiment. FIG. 17 is a side sectional view of another example of the core melt holding structure according to the eighth embodiment.

  The core melt holding structure of the eighth embodiment is characterized by the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 16, the sacrificial material 1G is composed of a high sacrificial material 1Ga made of a material having a low viscosity reducing effect and a low sacrificial material 1Gb made of a material having a low viscosity reducing effect. And at least two types. As described in the first embodiment, the lowering of the viscosity can be achieved by selecting a composition in order of decreasing effect of lowering the melting point of the core melt 10 and increasing the mass. .

  In the core melt holding structure of the eighth embodiment, the high sacrificial material 1Ga is arranged on the upper surface of the floor 150a that is the region below the reactor vessel 41, and the high sacrificial material 1Ga is surrounded by the floor 150a. A low sacrificial material 1Gb is disposed on the upper surface. The form of the sacrificial material 1G has the form described in the above-described second to sixth embodiments. Although the region where the high sacrificial material 1Ga is disposed is below the reactor vessel 41, this region includes at least the region immediately below the reactor vessel 41. The area | region which remove | deviates from directly under the furnace vessel 41 may be included. That is, in the core melt holding structure of the eighth embodiment, there is a region where the low sacrificial material 1Gb is disposed around the region where the high sacrificial material 1Ga is disposed.

  As described above, in the core melt holding structure of the eighth embodiment, the high sacrificial material 1Ga is arranged on the upper surface of the floor portion 150a below the reactor vessel 41, and the upper surface of the floor portion 150a is surrounded by the periphery of the high sacrificial material 1Ga. The low sacrificial material 1Gb is disposed on the substrate. Therefore, the core melt 10 is reduced in viscosity by the high sacrificial material 1Ga and spreads along the floor 150a, and then reaches the region where the low sacrificial material 1Gb is disposed while being cooled in a spread state. When reaching the region where the low sacrificial material 1Gb is disposed, the core melt 10 spreads and is easy to cool, and is further cooled by the low sacrificial material 1Gb while the viscosity is reduced. As a result, the situation where the floor 150a of the cavity chamber 150 made of concrete is eroded can be prevented, and damage to the structure 100 due to the core melt 10 can be prevented.

  Further, in the core melt holding structure of the eighth embodiment, it is desirable to dispose the low sacrificial material 1Gb in the lower layer of the high sacrificial material 1Ga.

  Accordingly, the core melt 10 having a low viscosity in the upper high sacrificial material 1Ga spreads along the floor 150a, and then lowers in viscosity in the lower low sacrificial material 1Gb. (Fluidity) decreases. For this reason, the core melt 10 can be held while suppressing the core melt 10 spreading along the floor 150a from staying thick on the floor 150a. As a result, the situation where the floor 150a of the cavity chamber 150 made of concrete is eroded can be prevented, and damage to the structure 100 due to the core melt 10 can be prevented.

[Embodiment 9]
FIG. 18 is a side sectional view of the core melt holding structure according to the ninth embodiment.

  The core melt holding structure of the ninth embodiment is characterized by the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 18, the sacrificial material 1 </ b> H is configured as an equipment structure or a part of the equipment structure installed below the reactor vessel 41. The facility structure includes, for example, a conduit support 160 that supports the conduit tube 65 (thimble tube 68) inside the cavity chamber 150. The facility structure also includes an outer surface member of the conduit tube 65. In addition, although not shown in the drawing, the facility structure includes walls and columns that constitute the cavity chamber 150 in the reactor containment vessel 11. That is, the facility structure indicates a structure existing inside the cavity chamber 150. The lower part of the reactor vessel 41 is a region including at least a part immediately below the reactor vessel 41, and includes a region that is removed from the region immediately below the reactor vessel 41 following the region immediately below the reactor vessel 41. You may go out.

  Further, when the sacrificial material 1H is provided in the equipment structure, the layered sacrificial material 1C of the fourth embodiment is wound around the equipment structure, or the linear sacrificial material 1D of the fifth embodiment is wound or entangled. Can be provided.

  The sacrificial material 1H may be disposed on the upper surface of the floor 150a of the cavity chamber 150.

  Thus, in the core melt holding structure of the ninth embodiment, the sacrificial material 1H is configured as an equipment structure installed below the reactor vessel 41 or as a part of the equipment structure. The sacrificial material 1H is melted and mixed with the core melt 10, thereby lowering the melting point of the core melt 10 and lowering the viscosity, so that the core melt 10 having reduced viscosity is the floor 150a of the cavity chamber 150. And spreads thinly and is sufficiently cooled in the thickness direction. Therefore, it can suppress that the core melt 10 stays thick on the floor 150a. As a result, the situation where the floor 150a of the cavity chamber 150 made of concrete is eroded can be prevented, and damage to the structure 100 due to the core melt 10 can be prevented.

[Embodiment 10]
FIG. 19 is a side sectional view of the core melt holding structure according to the tenth embodiment. FIG. 20 is a side sectional view showing the operation of the core melt holding structure according to the tenth embodiment.

  The core melt holding structure of the tenth embodiment is characterized by the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 19, the sacrificial material 1 </ b> I is supported by the support member 3 having a lower melting point than the melt of the core melt 10 and the sacrificial material 1 </ b> I. The sacrificial material 1 </ b> I is provided so as to be able to diffuse with the melting of the support member 3.

  The support member 3 supports the sacrificial material 1I so as not to diffuse, and may be configured as a weir as shown in FIG. 19, and is not clearly shown in the figure, but as a container for storing the sacrificial material 1I. It may be configured. The support member 3 is made of a material having a melting point lower than that of the melt in which the core melt 10 and the sacrificial material 1F are mixed. The support member 3 may include the composition of the sacrificial material 1 shown in the first embodiment.

  The sacrificial material 1 </ b> I is formed into a granular shape or a powder shape as shown in the third embodiment and arranged together by the support member 3 so that it can diffuse as the support member 3 melts. Further, the sacrificial material 1 </ b> I may be formed in a liquid state and supported by the support member 3 so that it can diffuse as the support member 3 melts. Further, the sacrificial material 1 </ b> I may be formed in the form of particles or powder as shown in Embodiment 3 and supported in the liquid by being supported in the liquid so that it can be diffused as the support member 3 melts.

  As described above, in the core melt holding structure of the tenth embodiment, the sacrificial material 1I is collectively supported by the support member 3 having a lower melting point than the melt of the core melt 10 and the sacrificial material 1I. It is provided so that it can diffuse with melting. When the support member 3 is melted, the sacrificial material 1I is melted and mixed with the core melt 10 as shown in FIG. 20, thereby lowering the melting point of the core melt 10 to lower the viscosity. For this reason, the core melt 10 having a reduced viscosity flows along the floor 150a of the cavity chamber 150, spreads thinly, and is sufficiently cooled in the thickness direction. Therefore, it can suppress that the core melt 10 stays thick on the floor 150a. As a result, the situation where the floor 150a of the cavity chamber 150 made of concrete is eroded can be prevented, and damage to the structure 100 due to the core melt 10 can be prevented. Moreover, since the sacrificial material 1I can be collectively supported, the inspection can be performed without removing or re-installing the sacrificial material 1I during the periodic inspection of the structure 100 (the floor 150a of the cavity chamber 150). .

[Embodiment 11]
FIG. 21 is a side sectional view of the core melt holding structure according to the eleventh embodiment. FIG. 22 is a side sectional view showing the operation of the core melt holding structure according to the eleventh embodiment.

  The core melt holding structure of the eleventh embodiment is characterized by the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 21, the sacrificial material 1 </ b> J is provided between the floor portion 150 a of the cavity chamber 150 that receives the core melt 10 and the reactor vessel 41 below the reactor vessel 41. In FIG. 21, the sacrificial material 1J is disposed on the upper surface of the floor 150a. The form of the sacrificial material 1J includes the forms shown in the above-described Embodiments 2 to 10 and Embodiments 12 to 14 described later.

  On the other hand, in the reactor containment vessel 11, an adjacent chamber 151 is disposed around the cavity chamber 150 below the reactor vessel 41. The adjacent room 151 forms a space where workers can enter during normal operation of the nuclear power plant. The cavity chamber 150 and the adjacent chamber 151 are communicated with each other by a communication portion 152. The communication portion 152 is provided with a blocking portion 4 that ensures airtightness between the cavity chamber 150 and the adjacent chamber 151 for isolation. The closed portion 4 is made of a material having a melting point lower than that of the melt of the core melt 10 and the sacrificial material 1J. The blocking part 4 may include the composition of the sacrificial material 1 shown in the first embodiment.

  As described above, in the core melt holding structure of the eleventh embodiment, the sacrificial material 1J is disposed in the cavity chamber 150 below the reactor vessel 41, while the communication portion 152 that communicates the cavity chamber 150 with the adjacent chamber 151. Is closed with airtightness in the closed portion 4. The sacrificial material 1J is melted and mixed with the core melt 10, thereby lowering the melting point of the core melt 10 to lower the viscosity. For this reason, the core melt 10 whose viscosity has been reduced flows along the floor 150 a of the cavity chamber 150 and spreads thinly. Thereafter, as shown in FIG. 22, when the closed portion 4 is melted by the core melt 10 that has spread along the floor 150 a, the core melt 10 spreads to the adjacent chamber 151 through the communication portion 152, and the heat transfer area is increased. As a result, the cooling performance is improved and sufficient cooling is achieved. Therefore, it can suppress that the core melt 10 stays thick on the floor 150a. As a result, the situation where the floor 150a of the cavity chamber 150 made of concrete is eroded can be prevented, and damage to the structure 100 due to the core melt 10 can be prevented.

[Embodiment 12]
FIG. 23 is a side sectional view of the core melt holding structure according to the twelfth embodiment. FIG. 24 is a side sectional view of another example of the core melt holding structure according to the twelfth embodiment.

  The core melt holding structure of the twelfth embodiment is characterized by the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 23, the sacrificial material 1 </ b> K is provided between the floor 150 a of the cavity chamber 150 that receives the core melt 10 and the reactor vessel 41 below the reactor vessel 41. In FIG. 23, the sacrificial material 1K is disposed along the floor 150a. The form of the sacrificial material 1K includes the forms shown in the above-described Embodiments 2 to 11 and Embodiments 13 and 14 described later.

  A cooling mechanism 5 is disposed below the sacrificial material 1K. The cooling mechanism 5 is disposed on the upper surface of the floor 150a of the cavity chamber 150, and is disposed along the floor 150a. In the cooling mechanism 5, a cooling pipe 5 b is disposed inside a base material (for example, concrete) 5 a that is stacked on the upper surface of the floor 150 a. In the cooling pipe 5b, a refrigerant is circulated, whereby the base material 5a and the periphery of the base material 5a are cooled.

  Thus, in the core melt holding structure of the twelfth embodiment, the cooling mechanism 5 is disposed below the sacrificial material 1K. The sacrificial material 1K is melted and mixed in the core melt 10, thereby lowering the melting point of the core melt 10 to lower the viscosity. For this reason, the core melt 10 whose viscosity has been reduced flows along the floor 150 a of the cavity chamber 150 and spreads thinly. In addition, the core melt 10 that has spread along the floor 150 a is sufficiently cooled in the thickness direction by the cooling mechanism 5 and is solidified above the cooling mechanism 5. Therefore, the core melt 10 can be held while suppressing the core melt 10 from staying thick on the floor 150a. As a result, the situation where the floor 150a of the cavity chamber 150 made of concrete is eroded can be prevented, and damage to the structure 100 due to the core melt 10 can be prevented.

  Further, in the core melt holding structure of the twelfth embodiment, as shown in FIG. 24, the sacrificial material 1K includes a high sacrificial material 1Ka made of a material having a high viscosity reducing effect and a material having a low viscosity reducing effect. And at least two types of low sacrificial material 1Kb. As described in the first embodiment, the lowering of the viscosity can be achieved by selecting a composition in order of decreasing effect of lowering the melting point of the core melt 10 and increasing the mass. .

  The sacrificial material 1K is formed by stacking a high sacrificial material 1Ka on the upper layer and a low sacrificial material 1Kb on the lower layer of the high sacrificial material 1Ka. A cooling mechanism 5 is disposed below the low sacrifice material 1Kb. That is, the high sacrificial material 1Ka is disposed at the uppermost position, and the low sacrificial material 1Kb is disposed between the high sacrificial material 1Ka and the cooling mechanism 5.

  Therefore, after the core melt 10 is reduced in viscosity in the upper high sacrificial material 1Ka and spreads along the floor 150a, the lower viscosity is reduced in the lower low sacrificial material 1Kb, that is, the viscosity is increased and the erosion rate is increased. (Fluidity) decreases. For this reason, the core melt 10 can be held while suppressing the core melt 10 spreading along the floor 150a from staying thick on the floor 150a. As a result, erosion of the core melt 10 to the cooling mechanism 5 can also be prevented.

[Embodiment 13]
FIG. 25 is a side sectional view of the core melt holding structure according to the thirteenth embodiment. FIG. 26 is a side sectional view of the sacrificial material of the core melt holding structure according to the thirteenth embodiment.

  The core melt holding structure of the thirteenth embodiment is characterized by the form of the sacrificial material 1 of the first embodiment described above. Specifically, as illustrated in FIG. 25, the sacrificial material 1L is accommodated in the container 6. The form of the sacrificial material 1L includes the forms shown in the above-described Embodiments 2 to 12 and Embodiment 14 described later.

  The container 6 is formed in a bowl shape with a material having a melting point higher than that of the core melt 10. Specifically, as shown in FIG. 26, the container 6 is configured to be surrounded by at least a side plate and a bottom plate and accommodate the sacrificial material 1L therein. The container 6 is formed with a large number of holes 6a such that at least the side plate and the bottom plate have a lattice shape or punched metal. In FIG. 26, the sacrificial material 1L is formed in a granular shape, but the hole 6a is formed in a size that does not drop the granular sacrificial material 1L. Further, the container 6 is provided with a hanging tool 6b such as an eyebolt on the upper surface thereof. The container 6 includes a sacrificial material 1L, and is designed to be, for example, several kilograms to several tens of kilograms. The container 6 can be installed or removed by being suspended by a hanging tool 6b using a crane. Moreover, the container 6 has the recessed part 6c in the lower part so that interference with the suspending tool 6b of the lower container 6 may be avoided when it piles up and down.

  Thus, in the core melt holding structure of the thirteenth embodiment, the sacrificial material 1L is accommodated in the container 6 formed in a bowl shape with a material having a melting point higher than that of the core melt 10. The sacrificial material 1L is melted and mixed with the core melt 10, thereby lowering the melting point of the core melt 10 to lower the viscosity. For this reason, a part of the core melt 10 whose viscosity has been reduced flows out through the hole 6 a of the vessel 6, flows along the floor 150 a of the cavity chamber 150, and spreads thinly. Therefore, it can suppress that the core melt 10 stays thick on the floor 150a. As a result, the situation where the floor 150a of the cavity chamber 150 made of concrete is eroded can be prevented, and damage to the structure 100 due to the core melt 10 can be prevented. In addition, a part of the core melt 10 whose viscosity has been reduced is finally solidified while remaining inside the container 6. Therefore, the core melt 10 can be recovered by removing the container 6.

[Embodiment 14]
In the fourteenth embodiment, the reactor containment vessel 11 is described in any one of the above-described embodiments, the reactor vessel 41, the floor 150a that is provided below the reactor vessel 41 and receives the core melt 10. And a core melt holding structure.

  Therefore, the core melt 10 flowing out of the reactor vessel 41 is melted and mixed with the sacrificial material of the core melt holding structure, thereby lowering the melting point and lowering the viscosity, flowing along the floor portion 150a, and spreading thinly. . Therefore, it can suppress that the core melt 10 stays thick on the floor 150a. As a result, it is possible to prevent the floor 150a of the cavity chamber 150 made of concrete from being eroded and to prevent the structure 100 constituting the reactor containment vessel 11 from being damaged by the core melt 10.

DESCRIPTION OF SYMBOLS 1 Sacrificial material 1a Upper layer sacrificial material 1b Lower layer sacrificial material 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, 1K, 1L Sacrificial material 1Aa Suspension tool 1Ea Suspension tool 1Eb Recessed part 1Ga High sacrificial material 1 Gb Low Sacrificial Material 1 Ka High Sacrificial Material 1 Kb Low Sacrificial Material 2 Weir 3 Support Member 4 Blocking Portion 5 Cooling Mechanism 5a Base Material 5b Cooling Pipe 6 Container 6a Hole 6b Suspension 6c Recess 10 Core Melt 11 Reactor Containment Vessel 12 Pressurized Water Type reactor 13 Steam generator 14, 15 Cooling water pipe 16 Pressurizer 17 Primary coolant circulation pump 18 Steam turbine 19 Condenser 20, 21 Cooling water pipe 22 Feed water pump 23 Generator 24 Intake pipe 25 Drain pipe 41 Reactor Vessel 42 Reactor vessel body 43 Reactor vessel lid 44 Stud bolt 45 Nut 46 Lower mirror 47 Inlet nozzle 48 Outlet nozzle 49 Top Core support plate 50 Lower core support plate 51 Core support rod 52 Upper core plate 53 Core tank 54 Lower core plate 55 Core 56 Fuel assembly 57 Control rod 58 Control rod cluster 59 Control rod cluster guide tube 60 Control rod drive device 61 Housing 62 Control rod cluster drive shaft 63 Instrumentation nozzle 64 In-core instrumentation guide pipe 65 Conduit tube 66, 67 Connecting plate 68 Thimble tube 69 Upper plenum 70 Lower plenum 71 Downcommer part 81 Ground 83 Upper compartment 84 Steam generator loop chamber 88 Fuel replacement water pit 100 Structure 150 Cavity chamber 150a Floor portion 150b Inclined surface 151 Adjacent chamber 152 Communication portion 160 Conduit support

Claims (7)

  Provided between the reactor vessel and the floor portion that receives the core melt below the reactor vessel, and sacrifices to lower the viscosity by lowering the melting point of the core melt by melting and mixing with the core melt Core melt holding structure with materials.   2. The core melt holding structure according to claim 1, wherein the sacrificial material includes one or more of an iron compound, an alkali compound, a silicate compound, calcium silicate, and alumina.   The core melt holding structure according to claim 1, wherein the sacrificial material has a mass of 10% or more with respect to a mass of the core melt.   The core melt holding structure according to any one of claims 1 to 3, wherein the sacrificial material is configured in a layered structure on the top and bottom, and the lower layer is configured with a material having a low viscosity reducing effect with respect to the upper layer.   The core melt holding structure according to claim 1, wherein the sacrificial material includes a reducing material that reduces a main composition of the core melt.   The core melt holding structure according to claim 1, wherein the sacrificial material includes a coolant that cools a main composition of the core melt. A reactor vessel;
A floor portion provided below the reactor vessel for receiving the core melt;
A core melt holding structure according to any one of claims 1 to 6,
A nuclear reactor containment vessel.

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