JP2019045340A - Corium holding structure and reactor container - Google Patents

Abstract

To provide a corium holding structure capable of preventing damage of a structure caused by corium.SOLUTION: A corium holding structure for receiving corium flowing out from a reactor vessel by the lower side of the reactor vessel, includes a sacrifice material 1A provided between the reactor vessel and a floor part 150a for receiving the corium under the reactor vessel, for lowering a melting point of the corium by being melted and mixed with the corium, to thereby lower viscosity thereof. The sacrifice material 1A is formed in the shape of a plurality of blocks.SELECTED DRAWING: Figure 8

Description

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

  In a nuclear power plant, as a severe accident, an accident in which a core melt flows out of a reactor vessel is assumed. If the core melt falls into the reactor containment cavity, the damage can be exacerbated if serious damage occurs to the structure forming the cavity. Therefore, it is necessary to take measures 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 forming a cavity chamber below the reactor vessel is provided, and the wall portion is a wall portion iron plate facing the cavity chamber, and A reactor containment vessel is shown having wall concrete provided on the outside of the wall iron plate and a wall liner provided on the outside of the wall concrete with respect to the cavity chamber.

  Also, conventionally, for example, in Patent Document 2, a core melt holding apparatus for receiving and holding core melt under the reactor vessel at the time of a core melt accident of the reactor, which is core melt adjacent to each other as a whole And a plurality of core melt holding blocks each having a through hole formed therein through which a coolant can flow, and a support base for supporting the core melt holding blocks. And the through holes formed in the plurality of core melt holding blocks are in communication with one another, and the coolant introduction unit for introducing the coolant into the through holes discharges the coolant from the through holes. A core melt holding device is shown which is disposed at a position lower than the core portion and is disposed so that the height position of the through hole gradually increases from the coolant introduction portion toward the coolant discharge portion. .

JP, 2016-166833, A Unexamined-Japanese-Patent No. 2014-081212

  In the reactor containment vessel disclosed in Patent Document 1 described above, the core melt flowing out of the reactor vessel is received by the cavity chamber provided below the reactor vessel, and blocked by the 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 for holding the core melt is the core melt. It absorbs heat from the object and dissipates heat to the side and lower surfaces to cool the core melt. As described above, conventionally, the core melt is blocked or cooled at the dropped place.

  However, if the core melt is blocked or cooled in a dropped place, it may not spread and stay thick in the area where the core melt dropped, that is, in a limited area. Then, when the core melt continues to fall, it is raised and held in a limited area, and the cooling of the lower inside is delayed, so that the erosion rate to a structure (such as floor concrete) forming the cavity chamber is high. There is a concern that the structure will melt and damage may occur.

  The present invention solves the above-mentioned problems, and an object of the present invention is to provide a core melt holding structure and a reactor containment vessel capable of preventing damage to a structure due to core melt.

  The core melt holding apparatus according to an aspect of the present invention is provided between a reactor vessel and a floor portion receiving the core melt below the reactor vessel, and is melted and mixed in the core melt. A sacrificial material is provided to lower the melting point of the core melt to lower the viscosity, and the sacrificial material is formed into a plurality of blocks.

  Further, in the molten core material holding device according to one aspect of the present invention, it is desirable that the block-shaped sacrificial material has a hanging member at the top.

  The core melt holding apparatus according to an aspect of the present invention is provided between a reactor vessel and a floor portion receiving the core melt below the reactor vessel, and is melted and mixed in the core melt. A sacrificial material is provided to lower the melting point of the core melt to lower the viscosity, and the sacrificial material is formed into a plurality of grains.

  Further, in the core melt holding apparatus according to one aspect of the present invention, it is desirable that the granular sacrificial material is accommodated in a container having a melting point lower than that of the core melt.

  The core melt holding apparatus according to an aspect of the present invention is provided between a reactor vessel and a floor portion receiving the core melt below the reactor vessel, and is melted and mixed in the core melt. A sacrificial material is provided which lowers the melting point of the core melt to lower the viscosity, and the sacrificial material is formed in layers.

  The core melt holding apparatus according to an aspect of the present invention is provided between a reactor vessel and a floor portion receiving the core melt below the reactor vessel, and is melted and mixed in the core melt. A sacrificial material is provided which lowers the melting point of the core melt to lower the viscosity, and the sacrificial material is formed in a linear shape.

  The core melt holding apparatus according to an aspect of the present invention is provided between a reactor vessel and a floor portion receiving the core melt below the reactor vessel, and is melted and mixed in the core melt. A sacrificial material is provided which lowers the melting point of the core melt to lower the viscosity, and the sacrificial material is formed into a plurality of blocks and has a hanging member at the top, and is lowered when stacked up and down. The lower part has a recess in order to avoid interference of the said suspension tool.

  The core melt holding apparatus according to an aspect of the present invention is provided between a reactor vessel and a floor portion receiving the core melt below the reactor vessel, and is melted and mixed in the core melt. A sacrificial material is provided to lower the melting point of the core melt to lower the viscosity, and the sacrificial material is disposed on the upper surface of the floor, and a region where the sacrificial material is not disposed on the floor around the sacrificial material is provided. Set up.

  Further, in the core melt holding device according to one aspect of the present invention, the core melt holding device is made of a material having a melting point lower than that of the core melt and the sacrificial material, and is disposed on the upper surface of the floor portion surrounding the sacrificial material. It is preferable to have a weir.

  The core melt holding apparatus according to an aspect of the present invention is provided between a reactor vessel and a floor portion receiving the core melt below the reactor vessel, and is melted and mixed in the core melt. A sacrificial material is provided to lower the melting point of the core melt to lower the viscosity, and the sacrificial material is composed of a high sacrificial material composed of a material having a high viscosity reducing effect and a material having a low viscosity reducing effect. The high sacrificial material is disposed on the upper surface of the floor below the reactor vessel, and the high sacrificial material is surrounded on the upper surface of the floor. Place the low sacrificial material.

  Further, in the molten core material holding device according to one aspect of the present invention, it is desirable to dispose the low sacrificial material also in the lower layer of the high sacrificial material.

  The core melt holding apparatus according to an aspect of the present invention is provided between a reactor vessel and a floor portion receiving the core melt below the reactor vessel, and is melted and mixed in the core melt. A sacrificial material is provided to lower the melting point of the core melt to lower the viscosity, and the sacrificial material is configured as a facility structure installed below the reactor vessel or as a part of the facility structure.

  The core melt holding apparatus according to an aspect of the present invention is provided between a reactor vessel and a floor portion receiving the core melt below the reactor vessel, and is melted and mixed in the core melt. A sacrificial material is provided to lower the melting point of the core melt to lower the viscosity, and the sacrificial material is collectively supported on a support member having a melting point lower than that of the core melt and the sacrificial material melt, and the support It is provided so as to be diffusable as the member melts.

  The core melt holding apparatus according to an aspect of the present invention is provided between a reactor vessel and a floor portion receiving the core melt below the reactor vessel, and is melted and mixed in the core melt. A sacrificial material is provided to lower the viscosity and lower the melting point of the core melt, and a cavity chamber disposed below the reactor vessel and in which the sacrificial material is disposed, and an adjacent chamber disposed around the cavity chamber. A communicating portion communicating between the cavity chamber and the adjacent chamber, and a material having a melting point lower than that of the core melt and the sacrificial material melt, and provided in the communicating portion to And a closed portion for ensuring airtightness between the adjacent chamber and isolation.

  The core melt holding apparatus according to an aspect of the present invention is provided between a reactor vessel and a floor portion receiving the core melt below the reactor vessel, and is melted and mixed in the core melt. A sacrificial material is provided to lower the melting point of the core melt to lower the viscosity, and a cooling mechanism is disposed below the sacrificial material.

  Further, in the molten core material holding device according to one aspect of the present invention, the sacrificial material is composed of a high sacrificial material composed of a material having a high viscosity reducing effect and a material having a low viscosity reducing effect. It is desirable to have at least two types of low sacrificial materials, arrange the high sacrificial material at the uppermost position, and arrange the low sacrificial material between the high sacrificial material and the cooling mechanism.

  The core melt holding apparatus according to an aspect of the present invention is provided between a reactor vessel and a floor portion receiving the core melt below the reactor vessel, and is melted and mixed in the core melt. A sacrificial material is provided to lower the melting point of the core melt to lower the viscosity, and the sacrificial material is accommodated in a vessel formed of a material having a melting point higher than that of the core melt.

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

  According to the present invention, the sacrificial material melts and mixes with the core melt flowing out of the reactor vessel, thereby lowering the melting point of the core melt and reducing the viscosity. The reduced viscosity core melt flows along the floor and spreads thinly, and is sufficiently cooled also in the thickness direction. For this reason, it is possible to prevent the core melt from remaining thickly in 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 from being eroded and to prevent damage to the structure due to the core melt.

FIG. 1 is a schematic configuration diagram showing an example of a nuclear power plant to which a 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 showing an example of a reactor containment vessel according to an embodiment of the present invention. FIG. 4 is a side cross-sectional view of the molten core retention structure according to the first embodiment 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 cross-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 a sacrificial material of the core melt holding structure according to the second embodiment of the present invention. FIG. 8 is a plan view of a sacrificial material of the core melt holding structure according to the second embodiment of the present invention. FIG. 9 is a side cross-sectional view of a core melt holding structure according to a third embodiment of the present invention. FIG. 10 is a side cross-sectional view of a core melt holding structure according to a fourth embodiment of the present invention. FIG. 11 is a side cross-sectional view of a core melt holding structure according to a fifth embodiment of the present invention. FIG. 12 is a side cross-sectional view of a core melt holding structure according to a sixth embodiment of the present invention. FIG. 13 is a side cross-sectional view of a core melt holding structure according to a seventh embodiment of the present invention. FIG. 14 is a side cross-sectional view showing an operation of a molten core retention structure according to a seventh embodiment of the present invention. FIG. 15 is a side cross-sectional view showing an operation of a molten core retention structure according to a seventh embodiment of the present invention. FIG. 16 is a side sectional view of a core melt holding structure according to an eighth embodiment 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 a ninth embodiment of the present invention. FIG. 19 is a side cross-sectional view of a core melt holding structure according to a tenth embodiment of the present invention. FIG. 20 is a side cross-sectional view showing an operation of a molten core retention structure according to a tenth embodiment of the present invention. FIG. 21 is a side sectional view of a core melt holding structure according to an eleventh embodiment of the present invention. FIG. 22 is a side cross sectional view showing an operation of a molten core retention structure according to an 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 cross-sectional view of another example of the core melt holding structure according to Embodiment 12 of the present invention. FIG. 25 is a side cross-sectional view of a core melt holding structure according to a thirteenth embodiment of the present invention. FIG. 26 is a side cross-sectional view of a sacrificial material of a core melt holding structure according to a thirteenth embodiment of the present invention.

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

  FIG. 1 is a schematic configuration diagram showing an example of a nuclear power plant to which a 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 showing an example of the reactor containment vessel according to the present embodiment.

  The reactor applied to the nuclear power plant of the present embodiment uses light water as a reactor coolant and a neutron moderator, uses high temperature and high pressure water that does not boil throughout the primary system, and sends this high temperature and high pressure water to a steam generator. It is a pressurized water reactor (PWR: Pressurized Water Reactor) which generates steam by heat exchange and sends this steam to a turbine generator for power generation.

  In a nuclear power plant having this pressurized water reactor, as shown in FIG. 1, the reactor containment vessel 11 contains a pressurized water reactor 12 and a steam generator 13 inside. The pressurized water reactor 12 and the steam generator 13 are connected via cooling water pipes 14 and 15. The coolant pipe 14 is provided with a pressurizer 16. The cooling water pipe 15 is provided with a primary coolant circulation pump 17. Accordingly, light water as the primary coolant is heated by the fuel constituting the core in the pressurized water reactor 12 and the high temperature light water is maintained at a predetermined high pressure by the pressurizer 16 through the cooling water pipe 14 to the steam generator 13 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. The reactor 12 is returned to.

  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. In addition, a generator 23 is connected to the steam turbine 18. The condenser 19 is connected to an intake pipe 24 and a drainage pipe 25 for supplying and discharging a cooling water (for example, seawater). Therefore, the steam generated by heat exchange 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 this steam drives the steam turbine 18 to generate electricity. The generator 23 generates power. 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.

  In addition, in the pressurized water reactor 12, as shown in FIG. 2, the reactor vessel 41 is provided with the reactor vessel main body 42 and the reactor vessel mounted thereon so that the reactor internals can be inserted therein. A cover (upper mirror) 43 is provided. A reactor vessel lid 43 is fixed to the reactor vessel main body 42 so as to be capable of opening and closing by a plurality of stud bolts 44 and nuts 45.

  The reactor vessel main body 42 has a cylindrical shape whose upper portion can be opened by removing the reactor vessel lid 43 and whose lower portion is closed by the 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 at the top and an outlet nozzle (outlet nozzle) 48 for discharging light water. The reactor vessel main body 42 is formed with a water injection nozzle (water injection nozzle) not shown separately from the inlet nozzle 47 and the outlet nozzle 48.

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

  Further, a core tank 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 portion of the core tank 53, and a lower core plate 54 having a large number of communicating holes (not shown) formed in a disk shape is connected to the lower portion. Lower core plate 54 is supported by lower core support plate 50.

  A core 55 is formed by the upper core plate 52, the core tank 53 and the lower core plate 54. The core 55 has a large number of fuel assemblies 56 disposed therein. Although not illustrated, the fuel assembly 56 is configured by bundling a large number of fuel rods in a grid shape by a support grid, and while the upper nozzle is fixed to the upper end, the lower nozzle is fixed to the lower end. The core 55 has a large number of control rods 57 disposed therein. A large number of control rods 57 are put together at their upper ends into control rod clusters 58, which can be inserted into the fuel assembly 56. The upper core support plate 49 penetrates the upper core support plate 49 itself, and a large number of control rod cluster guide pipes 59 are fixed. The lower ends of the control rod cluster guide pipes 59 extend to the control rod clusters 58 in the fuel assembly 56.

  The reactor vessel lid 43 constituting the reactor vessel 41 is provided with a control rod drive device 60 of a magnetic jack at the top. The control jack drive 60 of the magnetic jack is housed in a housing 61 integral with the reactor vessel lid 43. The upper ends of the large number of control rod cluster guide pipes 59 extend to the control rod drive 60. The control rod cluster drive shaft 62 extended from the control rod drive device 60 is extended through the control rod cluster guide tube 59 to the fuel assembly 56 so as to be able to grip the control rod cluster 58.

  The control rod drive device 60 is extended in the vertical direction and connected to the control rod cluster 58, and the control rod cluster drive shaft 62 formed by arranging a plurality of circumferential grooves on the surface at equal intervals in the longitudinal direction is a magnetic type The power of the reactor is controlled by moving the jack up and down.

  In addition, the reactor vessel main body 42 is provided with a large number of instrumentation nozzles 63 penetrating the lower mirror 46. In each instrumentation nozzle 63, an in-core instrumentation guide pipe 64 is fixed to the upper end portion inside the furnace, while a conduit tube 65 is connected to the lower end portion outside the furnace. An upper end portion of each in-core instrumentation guide tube 64 is connected to the lower core support plate 50. Upper and lower connecting plates 66 and 67 are attached to each in-core instrumentation guide tube 64 in order to suppress 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 through the lower core plate 54 to the fuel assembly 56. The thimble tube 68 is equipped with a neutron flux detector (not shown) capable of measuring the neutron flux.

  Therefore, by moving the control rod cluster drive shaft 62 by the control rod driving device 60 and inserting the control rod 57 into the fuel assembly 56, nuclear fission in the core 55 is controlled, and the generated heat energy causes the nuclear reactor vessel The light water charged into the chamber 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 which constitutes the fuel assembly 56 releases neutrons by fission of nuclear fuel, and light water as a moderator and primary cooling water lowers kinetic energy of the released fast neutrons to become thermal neutrons. While making it easy to cause nuclear fission, it takes heat generated and cools it. Further, by inserting the control rod 57 into the fuel assembly 56, the number of neutrons generated in the core 55 is adjusted, and when the reactor is urgently shut down, the core is rapidly inserted into the core 55.

  In the reactor vessel 41, an upper plenum 69 in communication with the outlet nozzle 48 is formed above the core 55, and 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 reactor vessel 41 and the core tank 53. Accordingly, light water flows into the reactor vessel main body 42 from the inlet nozzle 47, flows down the downcomer portion 71 downward to reach the lower plenum 70, and is guided upward by the spherical inner surface of the lower plenum 70 to rise. Then, after passing through the lower core support plate 50 and the lower core plate 54, they flow into the core 55. The light water that has flowed into the core 55 absorbs the heat energy generated from the fuel assemblies 56 that constitute the core 55, thereby cooling the fuel assemblies 56 while becoming hot and passing through the upper core plate 52. It rises to the upper plenum 69 and is discharged through the outlet nozzle 48.

  The reactor containment vessel 11 of the above-mentioned nuclear power plant is erected on a solid foundation 81 such as rock, as shown in FIG. 3, and a plurality of compartments such as an upper compartment 83 and steam generation inside by reinforced concrete etc. Loop chamber 84 is partitioned. A cylindrical structure 100 defining 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 connected by cooling water pipes 14 and 15.

  In addition, the reactor containment vessel 11 has a cavity 100 defined by the structure 100 below the reactor vessel 41 inside thereof. The nuclear reactor containment vessel 11 is provided with a refueling water pit 88. The refueling water pit 88 supplies a cooling water to the pressurized water reactor 12 in an emergency and cools the reactor cooling path (cooling water supply device) 89 and the cooling water by dispersing the cooling water in the reactor containment vessel 11 for cooling. The reactor containment vessel cooling path (cooling water supply device) 90 is connected. The cooling water dispersed in the reactor containment vessel 11 is stored in the cavity chamber 150 via a drain line (not shown) provided in the structure 100 from the steam generator loop chamber 84.

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

  As described above, 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, an embodiment of the core melt holding structure will be described.

Embodiment 1
FIG. 4 is a side sectional view of the molten core retention structure according to the first embodiment. FIG. 5 is a side cross-sectional view showing the function of the molten core retention 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 according to the first embodiment includes the sacrificial material 1 provided between the reactor vessel 41 and the floor 150 a of the 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.

  If the lower part of the reactor vessel 41 (the reactor vessel main body 42) is damaged by a severe accident involving melting of the core and the core melt 10 flows out of the reactor vessel 41, the reactor vessel 41 overflows. The core melt 10 drops toward the floor 150 a 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 molten core, and core internals melted along with the molten core.

  The sacrificial material 1 is melted and mixed in the core melt 10, thereby lowering the melting point of the core melt 10 to reduce the viscosity. For this reason, the core melt 10 reduced in viscosity flows along the floor 150 a of the cavity chamber 150, spreads thinly, and is sufficiently cooled even in the thickness direction. Therefore, it can be suppressed that the core melt 10 stays thick in the floor 150a. As a result, it is possible to prevent the floor portion 150 a of the cavity chamber 150 made of concrete from being eroded and to prevent damage to the structure 100 by the core melt 10.

The sacrificial material 1 contains one or more of a composition of an iron compound, an alkali compound, a silicate compound, calcium silicate (CaCiO ₃ ), and alumina (Al ₂ O ₃ ). Examples of iron compounds 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 and the like, magnesium-based Mg, MgO, Mg (OH) ₂ , MgCO ₃ and dolomite, sodium-based There are Na, Na ₂ O, NaOH, NaHCO ₃ , Na ₂ CO ₃ , sodium bicarbonate, Torona and the like. Examples of the silicate compound include SiO ₂ , sand, stones, calcium silicate, and magnesium silicate.

The core melt 10 and the sacrificial material 1 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 , and the melting point is relatively high, and as the temperature decreases, the viscosity increases and it is easy to set. For example, although the melting point of ZrO ₂ is about 3000 K, it decreases to about 1600 K when it is mixed with iron and calcium silicate, and to about 2500 K when it is mixed with calcium oxide (CaO). The core melt 10 having a lowered melting point is reduced in viscosity, and the above-described effects are achieved.

Here, the sacrificial material 1 has a low viscosity since Fe, CaCiO ₃ > CaO, MgO> SiO ₂ > Al ₂ O ₃ > UO ₂ , ZrO _{2 in} descending order of the effect of lowering the melting point and lowering the viscosity. It is desirable to include many compositions that have a large effect to be converted, and the above effects can be significantly obtained. The order of the composition is described in 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? It can be based on the description of pid = 135720).

  Also, 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. Is desirable. Then, it is desirable that the sacrificial material 1 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.

  Also, the sacrificial material 1 may be disposed at least below the reactor vessel 41, but it is mixed with the core melt 10 extending from the lower side of the reactor vessel 41 to the area outside the reactor vessel 41 to make the viscosity low. As shown in FIG. 4 and FIG. 5, it is desirable that they are also disposed in the area out of the area below the reactor vessel 41.

  In the form shown in FIG. 6, the sacrificial material 1 is configured in layers in the upper and lower direction, and in the figure, it is composed of the upper layer sacrificial material 1a and the lower layer sacrificial material 1b. In this configuration, it is desirable that the lower layer sacrificial material 1b be composed of a material having a low viscosity reducing effect with respect to the upper layer sacrificial material 1a. The lowering of the viscosity can be achieved by following the descending order of the effect of lowering the viscosity and lowering the melting point described above, or it can also be achieved by changing the mass of the same composition to reduce the melting point and reducing the viscosity.

  The number of layers is not limited to the above two layers, and the sacrificial material 1 may be formed in layers in the upper and lower layers, and the lower layer may be formed of a material having a low viscosity reducing effect with respect to the upper layer. Moreover, it is also included that each layer is not strictly divided and is configured to have a composition in which the viscosity reducing effect is gradually lowered toward the bottom.

  Therefore, after the core melt 10 reduced in viscosity in the upper layer spreads along the bed portion 150a, the effect of reducing viscosity decreases in the lower layer, that is, the viscosity increases and the erosion rate (flowability) decreases. For this reason, the core melt 10 can be held while suppressing the core melt 10 spread along the floor portion 150 a from being thickly retained on the floor portion 150 a. As a result, it is possible to prevent the floor portion 150 a of the cavity chamber 150 made of concrete from being eroded and to prevent damage to the structure 100 by the core melt 10. Note that by raising the eutectic temperature, the viscosity and the melting point can be increased without lowering the temperature, and a material that raises 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 agent include carbon (such as coke), hydrogen, sodium sulfite and the like. Specifically, the main composition ZrO ₂ of the core melt 10 is reduced by carbon C to CO ₂ and Zr. Thus, the melting point of the core melt 10 can be lowered and the viscosity can be lowered by the sacrificial material 1 containing the reducing material. For this reason, the core melt 10 reduced in viscosity flows along the floor 150 a of the cavity chamber 150, spreads thinly, and is sufficiently cooled even in the thickness direction. Therefore, it can be suppressed that the core melt 10 stays thick in the floor 150a. As a result, it is possible to prevent the floor portion 150 a of the cavity chamber 150 made of concrete from being eroded and to prevent damage to the structure 100 by the core melt 10.

Moreover, the sacrificial material 1 is not limited to the said composition. For example, the sacrificial material 1 may include a coolant that cools the main composition of the core melt 10. The coolant is, for example, a material containing crystal water, such as MgCl ₂ · 6H ₂ O, Na ₂ SO ₄ · 10H ₂ O, CaSO ₄ · 2H ₂ O, or the like. As described above, the sacrificial material 1 containing crystal water, which is a coolant, can be cooled by the latent heat of evaporation taken away when evaporating the crystal water to lower the melting point of the core melt 10 and reduce the viscosity. For this reason, the core melt 10 reduced in viscosity flows along the floor 150 a of the cavity chamber 150, spreads thinly, and is sufficiently cooled even in the thickness direction. Therefore, it can be suppressed that the core melt 10 stays thick in the floor 150a. As a result, it is possible to prevent the floor portion 150 a of the cavity chamber 150 made of concrete from being eroded and to prevent damage to the structure 100 by the core melt 10.

Second Embodiment
FIG. 7 is a perspective view of a sacrificial material of the core melt holding structure according to the second embodiment. FIG. 8 is a plan view of a sacrificial material of the molten core retention structure according to the second embodiment.

  The core melt holding structure of the second embodiment is characterized in 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 block shapes, 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 into an equilateral triangular prism, but it may be, for example, a square prism, an equilateral prism, a regular pentagonal prism, or a polygonal prism such as an orthohexagonal prism. The shape may be any shape provided side by side on the upper surface of the floor portion 150a. In addition, a hanging member 1Aa such as an eyebolt is provided on the upper surface of the sacrificial material 1A. One block-shaped sacrificial material 1A is designed, for example, to several kg to several tens kg, and can be installed or removed by suspending it with a crane or the like by the suspension 1Aa.

  As described above, in the core melt holding structure according to the second embodiment, the sacrificial material 1A is formed into a plurality of blocks, so that the individual mass is reduced to improve the portability. For this reason, installation can be performed easily. Further, in the molten core retention structure of the second embodiment, the sacrificial material 1A can be suspended by a crane or the like by the suspension 1Aa, and can be transported, installed or removed. Therefore, according to the core melt holding structure of the second embodiment, removal and re-installation can be easily performed at the time of periodic inspection of the structure 100 (the floor 150 a of the cavity chamber 150).

  Although not explicitly shown in the figure, in the molten core material holding structure according to the first embodiment, the sacrificial material 1A may be configured such that the sacrificial materials 1A line up on the upper surface of the floor portion 150a mutually fit due to unevenness or the like. By doing this, mutual positional deviation when arranged can be suppressed.

Third Embodiment
FIG. 9 is a side cross-sectional view of a molten core retention structure according to a third embodiment.

  The core melt holding structure of the third embodiment is characterized in 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 in a plurality of particles, and the particles 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, for example, to several g to several tens of g, and the plurality can be stored in a container such as a bag and transported and installed or removed. Granular includes powdery.

  As described above, in the core melt holding structure according to the third embodiment, since the sacrificial material 1B is formed in a plurality of grains, the individual mass is reduced to improve the portability. For this reason, installation can be performed easily. Therefore, according to the core melt holding structure of the third embodiment, removal and re-installation can be easily performed at the time of periodic inspection of the structure 100 (the floor 150 a of the cavity chamber 150). Moreover, in the core melt holding structure according to the third embodiment, the core portion can be installed in a complicated shape, an uneven portion or a gap without being influenced by the shape of the floor portion 150a to be spread, and the freedom of installation can be improved.

  Further, in the core melt holding structure of the third embodiment, it is desirable that the granular sacrificial material 1B be separately stored in a plurality of containers (for example, bags and the like) 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. Also, the container may be configured as a sacrificial material.

Fourth Embodiment
FIG. 10 is a side cross-sectional view of the core melt holding structure according to the fourth embodiment.

  The core melt holding structure of the fourth embodiment is characterized in 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 into a layer, and the layer is provided on the upper surface of the floor 150a. The layer includes a film, a film, a sheet, a tile, a panel and the like. In addition, the layered sacrificial material 1C can be wound, transported and installed or removed in a roll shape by having flexibility. 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 layers can be stacked and installed.

  As described above, in the core melt holding structure of the fourth embodiment, the sacrificial material 1C is formed in a layer form, so that the individual mass is reduced to improve the portability. For this reason, installation can be performed easily. Therefore, according to the core melt holding structure of the fourth embodiment, removal and re-installation can be easily performed at the time of periodic inspection of the structure 100 (the floor 150 a of the cavity chamber 150).

Fifth Embodiment
FIG. 11 is a side cross-sectional view of the core melt holding structure according to the fifth embodiment.

  The core melt holding structure of the fifth embodiment is characterized in 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 term "linear" includes fibrous, string, and rope shapes. In addition, the linear sacrificial material 1D can be wound and transported in a ring shape and can be installed or removed due to its flexibility. The linear sacrificial material 1D is designed to have a diameter of, for example, several mm to several tens mm, and can be installed by being entangled, bent, or wound.

  As described above, in the core melt holding structure of the fifth embodiment, the sacrificial material 1D is formed in a linear shape, so that the individual mass is reduced to improve the portability. For this reason, installation can be performed easily. Therefore, according to the core melt holding structure of the fifth embodiment, removal and re-installation can be easily performed at the time of periodic inspection of the structure 100 (the floor 150 a of the cavity chamber 150). Further, in the core melt holding structure of the fifth embodiment, it can be installed in a complicated shape, a concavo-convex portion and a gap without being influenced by the shape of the floor 150a to be spread, and the freedom of installation can be improved.

Sixth Embodiment
FIG. 12 is a side cross-sectional view of a core melt holding structure according to a sixth embodiment.

  The core melt holding structure of the sixth embodiment is characterized in 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 block shapes, and the blocks are provided side by side or stacked on the upper surface of the floor portion 150a. In addition, a hanging member 1Ea such as an eyebolt is provided on the upper surface of the sacrificial material 1E. One block-shaped sacrificial material 1E is designed, for example, to several kg to several tens kg, and can be installed or removed by suspending it with a crane or the like by the suspension tool 1Ea. Also, the sacrificial material 1E has a recess 1Eb in the lower part so as to avoid interference of the lower sacrificial material 1E with the suspension tool 1Ea when stacked up and down.

  As described above, in the core melt holding structure according to the sixth embodiment, the sacrificial material 1E is formed into a plurality of blocks, so that the individual mass is reduced to improve the portability. For this reason, installation can be performed easily. In the molten core retention structure of the sixth embodiment, the sacrificial material 1E can be suspended, transported, installed, or removed by a crane or the like by the suspension tool 1Ea. Therefore, according to the core melt holding structure of the sixth embodiment, removal and re-installation can be easily performed at the time of periodic inspection of the structure 100 (the floor 150 a of the cavity chamber 150). Moreover, in the core melt holding structure according to the sixth embodiment, the sacrificial material 1E is provided with the recess 1Eb for avoiding the lower suspension 1Ea, and mutual interference can be prevented even when stacked up and down.

Seventh Embodiment
FIG. 13 is a side sectional view of the core melt holding structure according to the seventh embodiment. FIG. 14 is a side cross-sectional view showing an operation of a molten core retention structure according to a seventh embodiment. FIG. 15 is a side cross-sectional view showing an operation of a molten core retention structure according to a seventh embodiment.

  The core melt holding structure of the seventh embodiment is characterized in 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 which is a region under the reactor vessel 41. There is a form shown in Embodiment 2-Embodiment 6 mentioned above as a form of sacrificial material 1F. In addition, the sacrificial material 1F is not disposed on the upper surface of the floor portion 150a which is a region out of the region below the reactor vessel 41 around the sacrificial material 1F. Although the area where the sacrificial material 1F is disposed is below the reactor vessel 41, this area is an area including at least immediately below the reactor vessel 41, and the area immediately below the reactor vessel 41 is followed by the reactor. It may include an area which is off directly below the container 41. That is, in the core melt holding structure of the seventh embodiment, there is a region where the floor portion 150a is exposed around the region where the sacrificial material 1F is disposed.

  As described above, in the core melt holding structure of the seventh embodiment, a region where the sacrificial material 1F is not disposed is provided around the region where the sacrificial material 1F is disposed. Therefore, the core melt 10 is reduced in viscosity by the sacrificial material 1F, spreads along the floor 150a, and then cooled in the expanded state to reach the area where the sacrificial material 1F is not disposed. When reaching the area where the sacrificial material 1F is not disposed, since the core melt 10 is spread, it is easy to cool and erosion on the floor 150a is suppressed. As a result, it is possible to prevent the floor portion 150 a of the cavity chamber 150 made of concrete from being eroded and to prevent damage to the structure 100 by the core melt 10. And since it has a field which does not arrange sacrificial material 1F, when performing periodic inspection of structure 100 (floor 150a of cavity room 150), inspection can be performed without removing sacrificial material 1F and re-installing.

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

  Therefore, as shown in FIG. 14, the core melt 10 is stored by the crucible 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 further improved. Do. Thereafter, as shown in FIG. 15, since the crucible 2 is melted by the melt in which the core melt 10 and the sacrificial material 1F are mixed, the low viscosity core melt 10 spreads along the floor 150a and spreads. It leads to the area where the sacrificial material 1F is not disposed while being cooled in the cold state. When reaching the area where the sacrificial material 1F is not disposed, since the core melt 10 is spread, it is easy to cool and erosion on the floor 150a is suppressed. As described above, by arranging the crucible 2, it is possible to promote melt mixing of the core melt 10 with the sacrificial material 1 F and to improve the viscosity reduction. As a result, it is possible to prevent the floor portion 150 a of the cavity chamber 150 made of concrete from being eroded and to prevent damage to the structure 100 by the core melt 10.

  Note that, as shown in FIGS. 13 to 15, in the area where the sacrificial material 1F is not disposed, an inclined surface 150b which is inclined downward as it is separated from the area where the sacrificial material 1F is disposed is formed in the floor 150a. Is desirable. For this reason, the core melt 10 can be easily spread along the inclined surface 150 b, and the cooling property of the core melt 10 can be improved.

[Eighth embodiment]
FIG. 16 is a side cross-sectional view of a core melt holding structure according to an 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 in the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 16, the sacrificial material 1G is a high sacrificial material 1Ga made of a material having a high viscosity reducing effect, and a low sacrificial material 1Gb having a material having a low viscosity reducing effect. And at least two types. The reduction in viscosity can be achieved by selecting the composition in order of magnitude of the effect of lowering the melting point of the core melt 10 and decreasing the melting point as described in the first embodiment, or by increasing the mass. .

  Then, in the core melt holding structure of the eighth embodiment, the high sacrificial material 1Ga is disposed on the upper surface of the floor 150a which is the lower region of the reactor vessel 41, and the high sacrificial material 1Ga is surrounded to surround the floor 150a. Place the low sacrificial material 1Gb on the top surface. The form of the sacrificial material 1G is the form described in the second to sixth embodiments described above. Although the region where the high sacrificial material 1Ga is disposed is the lower part of the reactor vessel 41, this region is a region including at least the region directly below the reactor container 41, and the region immediately below the reactor container 41 is atomically It may include a region which is off directly below the furnace vessel 41. 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 disposed on the upper surface of the floor 150a below the reactor vessel 41, and the upper surface of the floor 150a is surrounded by the high sacrificial material 1Ga. Place the low sacrificial material 1Gb on the Therefore, the core melt 10 is reduced in viscosity by the high sacrificial material 1Ga, spreads along the floor 150a, and then cooled while reaching the area where the low sacrificial material 1Gb is disposed while being spread. When reaching the area where the low sacrificial material 1 Gb is disposed, the core melt 10 is spread and thus is easy to cool, and the viscosity is further lowered while being lowered in viscosity by the low sacrificial material 1 Gb. As a result, it is possible to prevent the floor portion 150 a of the cavity chamber 150 made of concrete from being eroded and to prevent damage to the structure 100 by the core melt 10.

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

  Therefore, after the core melt 10 reduced in viscosity in the upper high sacrificial material 1Ga spreads along the floor 150a, the reduction in viscosity decreases in the lower low sacrificial material 1Gb, that is, the viscosity increases and the erosion rate (Fluidity) declines. For this reason, the core melt 10 can be held while suppressing the core melt 10 spread along the floor portion 150 a from being thickly retained on the floor portion 150 a. As a result, it is possible to prevent the floor portion 150 a of the cavity chamber 150 made of concrete from being eroded and to prevent damage to the structure 100 by the core melt 10.

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

  The core melt holding structure of the ninth embodiment is characterized in the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 18, the sacrificial material 1H is configured as a part of a facility structure or a facility structure installed below the reactor vessel 41. The facility structure has, for example, a conduit support 160 for supporting the conduit tube 65 (the thimble tube 68) inside the cavity chamber 150. The facility structure also includes the outer surface member of the conduit tube 65. In addition, although not clearly shown in the figure, the facility structure also includes walls, columns, and the like that constitute the cavity chamber 150 in the reactor containment vessel 11. That is, the facility structure represents a structure existing inside the cavity chamber 150. The lower side of the reactor vessel 41 is a region including at least a part immediately below the reactor vessel 41, and includes a region following the region directly below the reactor vessel 41 and coming off immediately below the reactor vessel 41. It may be.

  When the sacrificial material 1H is provided on the facility structure, the layered sacrificial material 1C of the fourth embodiment is wound around the outside of the facility structure, or the linear sacrificial material 1D of the fifth embodiment is wrapped or entangled. It can be provided by

  In addition, 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 a facility structure installed below the reactor vessel 41 or a part of the facility structure. Since the sacrificial material 1H is melted and mixed in the core melt 10, thereby lowering the melting point of the core melt 10 to reduce the viscosity, the core melt 10 having a reduced viscosity is the floor 150a of the cavity chamber 150. Flows along the wall, spreads thinly, and is sufficiently cooled in the thickness direction. Therefore, it can be suppressed that the core melt 10 stays thick in the floor 150a. As a result, it is possible to prevent the floor portion 150 a of the cavity chamber 150 made of concrete from being eroded and to prevent damage to the structure 100 by the core melt 10.

Tenth Embodiment
FIG. 19 is a side cross-sectional view of a core melt holding structure according to a tenth embodiment. FIG. 20 is a side cross-sectional view showing an operation of a molten core retention structure according to a tenth embodiment.

  The core melt holding structure of the tenth embodiment is characterized in the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 19, the sacrificial material 1I is supported by the support member 3 having a melting point lower than that of the core melt 10 and the molten material of the sacrificial material 1I. In addition, the sacrificial material 1I is provided so as to be diffused as the supporting member 3 is melted.

  The support member 3 supports the sacrificial material 1I in a lump so as not to diffuse, and may be configured as a weir as shown in FIG. 19 and is not explicitly shown in the figure, but as a container for containing 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 a mixture of the core melt 10 and the sacrificial material 1F. The support member 3 may contain the composition of the sacrificial material 1 shown in the first embodiment.

  The sacrificial material 1I is formed in the granular or powder form shown in the third embodiment so as to be diffused as the supporting member 3 melts, and is collected and arranged by the supporting member 3. In addition, the sacrificial material 1I may be formed in a liquid state and supported by the support member 3 so as to be diffused as the support member 3 melts. In addition, the sacrificial material 1I may be formed in the form of particles or powder as shown in the third embodiment, provided in a liquid, and supported by the support member 3 so that the sacrificial material 1I can be diffused as the support member 3 melts.

  Thus, in the core melt holding structure of the tenth embodiment, the sacrificial material 1I is collectively supported by the support member 3 having a melting point lower than that of the core melt 10 and the melt of the sacrificial material 1I. It is provided to be diffusable as it melts. The sacrificial material 1I melts and mixes with the core melt 10 as shown in FIG. 20 by melting the support member 3, thereby lowering the melting point of the core melt 10 to lower the viscosity. For this reason, the core melt 10 reduced in viscosity flows along the floor 150 a of the cavity chamber 150, spreads thinly, and is sufficiently cooled even in the thickness direction. Therefore, it can be suppressed that the core melt 10 stays thick in the floor 150a. As a result, it is possible to prevent the floor portion 150 a of the cavity chamber 150 made of concrete from being eroded and to prevent damage to the structure 100 by the core melt 10. Moreover, since the sacrificial material 1I can be collectively supported, the periodic inspection of the structure 100 (the floor 150a of the cavity chamber 150) can be performed without removing or re-installing the sacrificial material 1I. .

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

  The core melt holding structure of the eleventh embodiment is characterized in the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 21, the sacrificial material 1J is provided between the floor portion 150 a of the cavity chamber 150 receiving the core melt 10 below the reactor vessel 41 and the reactor vessel 41. In FIG. 21, the sacrificial material 1J is disposed on the top surface of the floor 150a. The form of the sacrificial material 1J includes the forms shown in the above-described second to tenth embodiments and the twelfth to fourteenth embodiments described later.

  On the other hand, in the reactor containment vessel 11, the adjacent chamber 151 is disposed around the cavity chamber 150 below the reactor vessel 41. The adjacent chamber 151 forms a space where workers enter during normal times of the nuclear power plant. The cavity chamber 150 and the adjacent chamber 151 communicate with each other by the communicating portion 152. The communication portion 152 is provided with a closed portion 4 which secures and isolates the air tightness between the cavity chamber 150 and the adjacent chamber 151. The closed portion 4 is made of a material having a melting point lower than that of the core melt 10 and the sacrificial material 1J. The closed portion 4 may include the composition of the sacrificial material 1 shown in the first embodiment.

  As described above, in the core melt holding structure according to the eleventh embodiment, the sacrificial material 1J is disposed in the cavity chamber 150 below the reactor vessel 41, while the communicating portion 152 communicating the cavity chamber 150 with the adjacent chamber 151. Is closed at the closing portion 4 in an airtight manner. The sacrificial material 1J is melt mixed into the core melt 10, thereby lowering the melting point of the core melt 10 to reduce the viscosity. For this reason, the core melt 10 reduced in viscosity 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 expanded along the floor 150a, the core melt 10 also spreads to the adjacent chamber 151 through the communicating portion 152, and the heat transfer area is expanded. Thus, the cooling performance is improved and sufficiently cooled. Therefore, it can be suppressed that the core melt 10 stays thick in the floor 150a. As a result, it is possible to prevent the floor portion 150 a of the cavity chamber 150 made of concrete from being eroded and to prevent damage to the structure 100 by the core melt 10.

[Embodiment 12]
FIG. 23 is a side cross-sectional view of a core melt holding structure according to a twelfth embodiment. FIG. 24 is a side cross-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 in the form of the sacrificial material 1 of the first embodiment described above. Specifically, as shown in FIG. 23, the sacrificial material 1 K is provided between the floor portion 150 a of the cavity chamber 150 receiving the core melt 10 below the reactor vessel 41 and the reactor vessel 41. In FIG. 23, the sacrificial material 1K is disposed along the floor 150a. The form of the sacrificial material 1K is as shown in the above-described second to eleventh embodiments and the thirteenth and fourteenth embodiments described later.

  Further, the cooling mechanism 5 is disposed below the sacrificial material 1K. The cooling mechanism 5 is disposed on the upper surface of the floor 150 a of the cavity chamber 150 and disposed along the floor 150 a. In the cooling mechanism 5, a cooling pipe 5 b is disposed inside a base material (for example, concrete) 5 a which is disposed by being stacked on the upper surface of the floor portion 150 a. A refrigerant is circulated inside the cooling pipe 5b, whereby the base 5a and the periphery of the base 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 melts and mixes with the core melt 10, thereby lowering the melting point of the core melt 10 to reduce the viscosity. For this reason, the core melt 10 reduced in viscosity flows along the floor 150 a of the cavity chamber 150 and spreads thinly. Further, the core melt 10 spread along the floor 150 a is sufficiently cooled also in the thickness direction by the cooling mechanism 5, and solidifies above the cooling mechanism 5. Therefore, the core melt 10 can be held while suppressing the core melt 10 from staying thick in the floor portion 150 a. As a result, it is possible to prevent the floor portion 150 a of the cavity chamber 150 made of concrete from being eroded and to prevent damage to the structure 100 by the core melt 10.

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

  The sacrificial material 1K is configured by disposing the high sacrificial material 1Ka in the upper layer, and disposing and laminating the low sacrificial material 1Kb in the lower layer of the high sacrificial material 1Ka. The cooling mechanism 5 is disposed below the low sacrificial material 1 Kb. 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, the core melt 10 is reduced in viscosity at the high sacrificial material 1Ka in the upper layer and spread along the floor 150a, and then the viscosity reduction in the lower low sacrificial material 1Kb is reduced, that is, the viscosity is increased and the erosion rate is increased. (Fluidity) declines. For this reason, the core melt 10 can be held while suppressing the core melt 10 spread along the floor portion 150 a from being thickly retained on the floor portion 150 a. As a result, erosion of the core melt 10 into the cooling mechanism 5 can also be prevented.

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

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

  The container 6 is formed in a bowl shape of 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 so that the sacrificial material 1L can be accommodated therein. In the container 6, at least the side plate and the bottom plate are formed with a large number of holes 6a such as a lattice or punching metal. In FIG. 26, although 1 L of sacrificial materials are formed in the granular form, the hole 6a is formed in the magnitude | size which does not drop out 1 L of granular sacrificial materials. The container 6 is provided with a hanging tool 6b such as an eyebolt on the top surface thereof. The container 6 includes the sacrificial material 1L, and is designed to have, for example, a few kg to a few dozen kgs, and can be installed or removed by hanging with a crane or the like by the suspension tool 6b. Moreover, the container 6 has the recessed part 6c in the lower part so that interference with the suspension tool 6b of the lower container 6 may be avoided, when stacking up and down.

  As described above, 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 melt mixed into the core melt 10, thereby lowering the melting point of the core melt 10 to reduce the viscosity. For this reason, a part of the core melt 10 reduced in viscosity 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 be suppressed that the core melt 10 stays thick in the floor 150a. As a result, it is possible to prevent the floor portion 150 a of the cavity chamber 150 made of concrete from being eroded and to prevent damage to the structure 100 by the core melt 10. In addition, a part of the core melt 10 reduced in viscosity is finally solidified while remaining inside the vessel 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 the reactor vessel 41, the floor portion 150a provided below the reactor vessel 41 and receiving the core melt 10, and any one of the above-described embodiments. A core melt holding structure of

  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 reducing the viscosity, and flows along the floor 150a and spreads thinly. . Therefore, it can be suppressed that the core melt 10 stays thick in the floor 150a. As a result, it is possible to prevent the floor portion 150 a of the cavity chamber 150 made of concrete from being eroded and to prevent the structure 100 forming 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, 1D, 1E, 1F, 1G, 1H, 1I, 1J, 1K, 1L sacrificial material 1Aa suspension tool 1Ea suspension tool 1Eb recessed part 1Ga high sacrificial material 1Gb low sacrificial material 1Ka high sacrificial material 1Kb low sacrificial material 2 堰 3 support member 4 closed part 5 cooling mechanism 5a base material 5b cooling pipe 6 container 6a hole 6b suspension tool 6c recess 10 core melt 11 reactor containment vessel 12 pressurized water Type reactor 13 Steam generator 14, 15 Cooling water piping 16 Pressurizer 17 Primary coolant circulation pump 18 Steam turbine 19 Condenser 20, 21 Cooling water piping 22 Water supply pump 23 Generator 24 Intake pipe 25 Drain pipe 41 Reactor Vessel 42 reactor vessel main body 43 reactor vessel lid 44 stud bolt 45 nut 46 lower mirror 47 inlet nozzle 48 outlet nozzle 49 above 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 61 housing 62 Control rod cluster drive shaft 63 Instrumentation nozzle 64 In-instrument guide pipe 65 Conduit tube 66, 67 Connecting plate 68 Thimble tube 69 Upper plenum 70 Lower plenum 71 Down-comer portion 81 Ground 83 Upper compartment 84 Steam generator loop chamber 88 Refueling water pit 100 Structure 150 Cavity chamber 150a Floor 150b Slope 151 Adjacent chamber 152 Communication 160 Conduit support

Claims (18)

It is provided between a reactor vessel and a bed portion receiving a core melt below the reactor vessel, and is mixed with the core melt to lower the melting point of the core melt to lower the viscosity. Equipped with
The core melt holding structure, wherein the sacrificial material is formed in a plurality of blocks.   The core melt retention structure according to claim 1, wherein the block-shaped sacrificial material has a suspension at the top. It is provided between a reactor vessel and a bed portion receiving a core melt below the reactor vessel, and is mixed with the core melt to lower the melting point of the core melt to lower the viscosity. Equipped with
The core melt holding structure, wherein the sacrificial material is formed in a plurality of grains.   The core melt holding structure according to claim 3, wherein the granular sacrificial material is accommodated in a container having a melting point lower than that of the core melt. It is provided between a reactor vessel and a bed portion receiving a core melt below the reactor vessel, and is mixed with the core melt to lower the melting point of the core melt to lower the viscosity. Equipped with
The sacrificial material is a core melt holding structure formed in a layer. It is provided between a reactor vessel and a bed portion receiving a core melt below the reactor vessel, and is mixed with the core melt to lower the melting point of the core melt to lower the viscosity. Equipped with
The core material holding structure wherein the sacrificial material is formed in a linear shape. It is provided between a reactor vessel and a bed portion receiving a core melt below the reactor vessel, and is mixed with the core melt to lower the melting point of the core melt to lower the viscosity. Equipped with
The sacrificial material is formed into a plurality of blocks and has a suspension at the top, and has a recess at the bottom to avoid interference with the suspension below when stacked up and down. Core melt holding structure. It is provided between a reactor vessel and a bed portion receiving a core melt below the reactor vessel, and is mixed with the core melt to lower the melting point of the core melt to lower the viscosity. Equipped with
A core melt holding structure in which the sacrificial material is disposed on the upper surface of the floor and a region in which the sacrificial material is not disposed on the floor around the sacrificial material is provided.   The core melt according to claim 8, comprising a material having a melting point lower than that of the core melt and the melt of the sacrificial material, and having a weir disposed on the upper surface of the floor portion surrounding the sacrificial material. Holding structure. It is provided between a reactor vessel and a bed portion receiving a core melt below the reactor vessel, and is mixed with the core melt to lower the melting point of the core melt to lower the viscosity. Equipped with
The sacrificial material has at least two types of a high sacrificial material composed of a material having a high viscosity reducing effect and a low sacrificial material composed of a material having a low viscosity reducing effect,
A core melt holding structure in which the high sacrificial material is disposed on the upper surface of the floor below the reactor vessel, and the low sacrificial material is disposed on the upper surface of the floor surrounding the high sacrificial material.   The core melt retention structure according to claim 10, wherein the low sacrificial material is disposed also below the high sacrificial material. It is provided between a reactor vessel and a bed portion receiving a core melt below the reactor vessel, and is mixed with the core melt to lower the melting point of the core melt to lower the viscosity. Equipped with
The core material holding structure, wherein the sacrificial material is a facility structure installed below the reactor vessel or a part of the facility structure. It is provided between a reactor vessel and a bed portion receiving a core melt below the reactor vessel, and is mixed with the core melt to lower the melting point of the core melt to lower the viscosity. Equipped with
The core melt holding structure, wherein the sacrificial material is collectively supported by a support member having a melting point lower than that of the core melt and the melt of the sacrificial material, and is diffused so as to melt the support member. It is provided between a reactor vessel and a bed portion receiving a core melt below the reactor vessel, and is mixed with the core melt to lower the melting point of the core melt to lower the viscosity. Equipped with
A cavity chamber disposed below the reactor vessel and in which the sacrificial material is disposed;
An adjacent chamber disposed around the cavity chamber,
A communicating portion communicating between the cavity chamber and the adjacent chamber;
A closed part made of a material having a melting point lower than that of the core melt and the sacrificial material and provided in the communicating part to ensure airtightness between the cavity chamber and the adjacent chamber,
Core melt holding structure. It is provided between a reactor vessel and a bed portion receiving a core melt below the reactor vessel, and is mixed with the core melt to lower the melting point of the core melt to lower the viscosity. Equipped with
A core melt holding structure in which a cooling mechanism is disposed below the sacrificial material. The sacrificial material has at least two types of a high sacrificial material composed of a material having a high viscosity reducing effect and a low sacrificial material composed of a material having a low viscosity reducing effect,
The core melt retention structure according to claim 15, wherein the high sacrificial material is disposed at the uppermost position, and the low sacrificial material is disposed between the high sacrificial material and the cooling mechanism. It is provided between a reactor vessel and a bed portion receiving a core melt below the reactor vessel, and is mixed with the core melt to lower the melting point of the core melt to lower the viscosity. Equipped with
The core melt holding structure, wherein the sacrificial material is accommodated in a vessel formed in a bowl shape with a material having a melting point higher than that of the core melt. Reactor vessel,
A floor portion provided below the reactor vessel for receiving a core melt;
The core melt holding structure according to any one of claims 1 to 17,
Reactor Containment Vessel with.

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