JP2009075001A - Nuclear reactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve heat exchange efficiency by uniformly supplying a coolant introduced radially and circumferentially into a pressure vessel from a lower plenum to a core in a nuclear reactor. <P>SOLUTION: In the nuclear reactor, a core barrel 46 is placed in a reactor vessel 41 with an inlet nozzle 44 and an outlet nozzle 45 and the core 53 is placed in the core barrel 46. Meanwhile, the lower plenum 58 is partitioned by the lower core plate 48 and the reactor vessel 41, a downcomer section 59 is partitioned by the reactor vessel 41 and the side wall of the core barrel 46 to form in the lower core plate 48 numerous communicating holes 61, 62, 63 and so on which allow the core 53 and the lower plenum 58 to communicate with each other and porous plates 71 to change the flow resistance of light water streaming in the communicating holes 61, 62 and 63 located in the center are provided in the upper part of the lower core plate 48. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a nuclear reactor having a core inside, and more particularly to a cooling structure for a core.

  In a pressurized water reactor (PWR), light water is used as a reactor coolant and neutron moderator, and is converted into high-temperature and high-pressure water that does not boil throughout the primary system, and this high-temperature and high-pressure water is sent to a steam generator for heat. Steam is generated by exchange, and the steam is sent to a turbine generator to generate electricity.

  In such a pressurized water reactor, a coolant is introduced into the reactor from the outside, and the core is cooled by circulating inside the reactor. That is, the coolant flows from a plurality of coolant inlet nozzles formed in the reactor vessel, and flows down the downcomer portion formed between the reactor vessel and the reactor core tank to reach the lower plenum. The coolant is guided upward by the spherical inner surface of the lower plenum and then moves upward. After passing through the lower core plate and the like, the coolant flows into the core. The coolant flowing into the core absorbs the heat energy generated from the fuel assemblies that make up the core, thereby cooling the fuel assemblies, while at the same time becoming hot and rising up to the upper plenum, forming in the reactor vessel. Through the cooled coolant outlet nozzle.

  In such a pressurized water reactor, structures such as a radial key that supports the core tank in the lower plenum and an in-core instrumentation guide tube that inserts inspection equipment into the fuel assembly are provided. The coolant supplied to the lower plenum collides with this structure and disperses, resulting in a flow distribution in the radial direction and the circumferential direction with respect to the core.

  Therefore, by inserting an orifice plate into a large number of communication holes formed in the center portion of the lower core plate, the flow resistance of the communication holes in the center portion of the lower core plate is increased and uniform in the radial direction of the core. The coolant flow rate is adjusted to achieve a flow rate distribution. Further, as in the reactor internal structure described in Patent Document 1 below, a connecting plate whose outer peripheral shape forms an asymmetrical shape in the flow direction of the main flow of the coolant is provided in the lower plenum to generate and promote separation vortices. Is suppressed, the coolant flows uniformly into the core, the pressure loss of the coolant flow is reduced, and the coolant flow is stabilized.

JP 2005-009999 A

  However, if an orifice plate is inserted into the communication hole at the center of the lower core plate, the flow resistance of the communication hole increases, and the flow rate distribution of the coolant becomes uniform in the radial direction of the core, but a large number of communication holes are provided. It is difficult to insert the orifice plate, and when the orifice plate is inserted into the communication hole, the flow velocity of the coolant is increased only by that portion, and the high-speed coolant is supplied to the core. There is a problem that the rod vibrates and interferes with the operation of the reactor. Moreover, in the reactor internal structure of patent document 1, the coolant which flowed in from the several coolant inlet nozzle descend | falls, joining at a downcomer part, and it is an upward upward flow by the inner surface shape in a lower plenum. Although the generation of large vortices is suppressed by the connecting plate, the vortex that has passed through the connecting plate and the vortex based on the connecting plate are likely to be generated, and the radial and circumferential directions with respect to the core It becomes difficult to form a uniform coolant flow.

  The present invention solves the above-mentioned problems, and is intended to improve the heat exchange efficiency by uniformly supplying the coolant introduced into the pressure vessel from the lower plenum to the core in the radial direction and the circumferential direction. The purpose is to provide a furnace.

  In order to achieve the above object, a nuclear reactor of the invention of claim 1 includes a reactor containment vessel, a pressure vessel accommodated in the reactor containment vessel, and cooling for supplying a coolant into the pressure vessel. Communication for supplying coolant to the nuclear fuel in a nuclear reactor that generates steam by heat exchange between the nuclear fuel and the coolant and generates power by driving a power generation turbine with the generated steam A flow resistance changing member for changing the flow resistance of the coolant is provided at the inlet or the outlet of the hole.

  According to a second aspect of the present invention, there is provided a reactor including a pressure vessel having a coolant inlet nozzle and a coolant outlet nozzle at an upper portion thereof, a core tank disposed in the pressure vessel, and a core disposed in the core vessel. And a core plate connected to the lower part of the core tank to support the core, a lower plenum defined by the core plate and the pressure vessel, and defined by the pressure vessel and the side wall of the core tank. In the nuclear reactor having a downcomer portion communicating with the coolant inlet nozzle and communicating with the lower plenum, the core plate is formed with a plurality of communication holes for communicating the core and the lower plenum, and the core A flow resistance changing member for changing the flow resistance of the coolant flowing in the communication hole is provided at an upper portion or a lower portion of the plate.

  In the nuclear reactor according to a third aspect of the present invention, the flow resistance changing member is configured to flow in a communication hole formed in a central portion of the core plate with respect to a flow resistance of the communication hole formed in an outer peripheral portion of the core plate. It is characterized by a large resistance. In short, it is only necessary to increase the flow resistance of the communication hole in the central part of the core plate compared to the communication hole in the outer peripheral part of the core plate. In this case, the flow resistance changing member is not provided in the communication hole in the outer peripheral part of the core plate. In addition, the flow resistance changing member may be provided in a communication hole in the center of the core plate.

  The nuclear reactor according to a fourth aspect of the invention is characterized in that a perforated plate is provided as an inlet portion or an outlet portion of a communication hole formed in a central portion of the core plate as the flow resistance changing member.

  In the nuclear reactor according to the fifth aspect of the present invention, the aperture ratio of the perforated plate provided in the communication hole located on the center side of the core plate is provided in the communication hole located on the outer peripheral side of the core plate. It is characterized by being set lower than the aperture ratio of the perforated plate.

  In the nuclear reactor according to claim 6, the porous plate is attached to an upper surface or a lower surface of the core plate via a support tube, and is provided in the communication hole located on the center side of the core plate. Is set lower than the height of the perforated plate provided in the communication hole located on the outer peripheral side of the core plate.

  In the nuclear reactor according to a seventh aspect of the invention, the perforated plate is attached to an upper surface or a lower surface of the core plate via a support cylinder, and a flow path is formed in the support cylinder.

  In the nuclear reactor according to claim 8, the height of the porous plate provided in the communication hole located on the center side of the core plate is provided in the communication hole located on the outer peripheral side of the core plate. It is characterized by being set lower than the height of the perforated plate.

  In the nuclear reactor according to the ninth aspect of the present invention, the flow path of the support cylinder is formed on the center side of the core plate.

  The nuclear reactor according to the invention of claim 10 is characterized in that an inner cylinder having a number of flow paths is provided inside the support cylinder.

  The nuclear reactor according to the invention of claim 11 is characterized in that an aperture ratio adjusting member capable of adjusting the aperture ratio of the perforated plate is provided.

  In the nuclear reactor according to the twelfth aspect of the present invention, a guide member for introducing a coolant that flows below the core plate into the communication hole is provided as the flow resistance changing member.

  In the nuclear reactor of the thirteenth aspect, the height of the guide member provided in the communication hole located on the center side of the core plate is provided in the communication hole located on the outer peripheral side of the core plate. It is characterized by being set lower than the height of the guide member.

  According to the reactor of the first aspect of the present invention, the pressure vessel is accommodated in the reactor containment vessel, the coolant supply piping system for supplying the coolant to the pressure vessel is provided, and the heat between the nuclear fuel and the coolant is provided. Steam is generated by replacement, and the power generation turbine is driven by the generated steam to generate power, and the flow resistance of the coolant is changed to the inlet or outlet of the communication hole for supplying coolant to the nuclear fuel. Since the flow resistance changing member is provided, when the coolant introduced into the pressure vessel is supplied to the nuclear fuel from the communication hole, the flow resistance of the coolant flowing in the communication hole is adjusted by the flow resistance changing member. Thus, the flow rate of the coolant supplied to the core is uniformly adjusted in the radial direction with respect to the core, and the heat exchange efficiency can be improved.

  According to the nuclear reactor of the invention of claim 2, the core tank is disposed in the pressure vessel having the coolant inlet nozzle and the coolant outlet nozzle, and the core is disposed in the core vessel, while the core plate and the pressure vessel are used. The lower plenum is divided and the downcomer section is divided by the pressure vessel and the side wall of the core tank, and a large number of communication holes for connecting the core and the lower plenum are formed in the core plate, and also communicated with the upper or lower part of the core plate. Since a flow resistance changing member is provided to change the flow resistance of the coolant flowing in the hole, the coolant introduced into the pressure vessel descends the downcomer section to the lower plenum and reverses at this lower plenum. The flow rate distribution of the rising coolant is higher at the center of the lower plenum, but by adjusting the flow resistance of the coolant flowing in the communication hole by the flow resistance changing member, Flow rate of the coolant supplied to the core becomes to be uniformly adjusted radially relative to the core, thereby improving the heat exchange efficiency.

  According to the nuclear reactor of the invention of claim 3, the flow resistance changing member is configured such that the flow resistance of the communication hole formed in the central portion of the core plate is different from the flow resistance of the communication hole formed in the outer peripheral portion of the core plate. Therefore, the flow rate distribution of the coolant rising from the lower plenum toward the core is higher in the center, but is adjusted so that the flow resistance of the communication hole in the center is increased by the flow resistance changing member. Thus, the flow rate of the coolant supplied to the core can be adjusted uniformly in the radial direction.

  According to the nuclear reactor of the invention of claim 4, since the porous plate is provided at the inlet portion or the outlet portion of the communication hole formed in the center portion of the core plate as the flow resistance changing member, the attachment of the porous plate to the communication hole and Removal becomes easy and workability can be improved.

  According to the nuclear reactor of the fifth aspect of the present invention, the aperture ratio of the porous plate provided in the communication hole located on the center side of the core plate is set to be equal to that of the porous plate provided in the communication hole located on the outer peripheral side of the core plate. Since the opening ratio is set lower than that, the flow resistance of the communication hole located on the center side of the core plate and the communication hole located on the outer peripheral side can be adjusted with a simple configuration, and the cost can be reduced. .

  According to the reactor of the invention of claim 6, the perforated plate is attached to the upper surface or the lower surface of the core plate via the support cylinder, and the height of the perforated plate provided in the communication hole located on the center side of the core plate is set. Since the height of the porous plate provided in the communication hole located on the outer peripheral side of the core plate is set lower than the height of the porous plate, the flow resistance of the communication hole can be adjusted by the height of the porous plate, the structure is simplified and the cost is low. Can be made possible.

  According to the reactor of the invention of claim 7, the porous plate is attached to the upper surface or the lower surface of the core plate via the support cylinder, and the flow path is formed in the support cylinder, so that the coolant is not limited to the holes of the porous plate. Then, it flows into the communication hole through the flow path of the support cylinder, and it becomes easy to guide the coolant to the core side, and a sufficient allowance for adjusting the flow resistance can be secured.

  According to the nuclear reactor of the eighth aspect of the present invention, the height of the porous plate provided in the communication hole located on the center side of the core plate is set to the height of the porous plate provided in the communication hole located on the outer peripheral side of the core plate. Since it is set lower than the height, the flow resistance of the communication hole can be adjusted by the height of the perforated plate, and the structure can be simplified and the cost can be reduced.

  According to the nuclear reactor of the ninth aspect of the present invention, since the flow path of the support cylinder is formed at the center side of the core plate, the coolant that descends the downcomer portion and reaches the lower plenum is reversed by the lower plenum. Since the center portion is raised, the raised coolant flows into the communication hole through the flow channel facing the center side of the support cylinder, and is easily guided to the core side, so that the flow resistance of the communication hole can be easily adjusted. .

  According to the nuclear reactor of the invention of claim 10, since the inner cylinder having a large number of flow paths is provided inside the support cylinder, the coolant flows in two stages of the flow path of the support cylinder and the flow path of the inner cylinder. Since the resistance is adjusted, it is easy to guide to the core side, and a sufficient allowance for adjusting the flow resistance can be secured.

  According to the nuclear reactor of the eleventh aspect of the invention, since the aperture ratio adjusting member capable of adjusting the aperture ratio of the porous plate is provided, the aperture ratio adjusting member opens the porous plate according to the flow distribution of the coolant in the lower plenum. By adjusting the rate, the flow rate of the coolant supplied to the core can be easily and uniformly adjusted.

  According to the nuclear reactor of the twelfth aspect of the present invention, the flow resistance changing member is provided with the guide member for introducing the coolant flowing under the core plate into the communication hole, so that the downcomer portion is lowered to the lower plenum. The coolant reverses at the lower plenum and rises in the center, so that the raised coolant flows into the communication hole by the guide member and is easily guided to the core side, and easily adjusts the flow resistance of the communication hole. be able to.

  According to the reactor of the thirteenth aspect of the present invention, the height of the guide member provided in the communication hole located on the center side of the core plate is set to the height of the guide member provided in the communication hole located on the outer peripheral side of the core plate. Since it is set lower than the height, the flow resistance of the communication hole can be adjusted by the height of the guide member, and the structure can be simplified and the cost can be reduced.

  Exemplary embodiments of a nuclear reactor according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, this invention is not limited by this Example.

  1 is a schematic configuration diagram showing the internal structure of a pressurized water reactor according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1, and FIG. 4 is a plan view of a porous plate fixed to the lower core plate of the first embodiment, and FIG. 5 is a schematic configuration diagram of a nuclear power plant having a pressurized water reactor of the first embodiment.

  The nuclear reactor of Example 1 uses light water as a reactor coolant and a neutron moderator, and produces high-temperature and high-pressure water that does not boil over the entire core, and sends this high-temperature and high-pressure water to a steam generator to generate steam by heat exchange. This is a pressurized water reactor (PWR) that generates electricity by sending this steam to a turbine generator.

  In the nuclear power plant having the pressurized water reactor of the present embodiment, as shown in FIG. 5, a pressurized water reactor 12 and a steam generator 13 are stored in the reactor containment vessel 11. The reactor 12 and the steam generator 13 are connected via cooling water pipes (coolant supply pipe systems) 14 and 15, a pressurizer 16 is provided in the cooling water pipe 14, and the cooling water is supplied to the cooling water pipe 15. A pump 15a is provided. In this case, light water is used as the moderator and the primary cooling water, and the primary cooling system is controlled by the pressurizer 16 so as to maintain a high pressure state of about 150 to 160 atm in order to suppress boiling of the primary cooling water in the core. is doing. Therefore, in the pressurized water reactor 12, light water is heated as the primary cooling water by the low-enriched uranium or MOX as the fuel (nuclear fuel), and the high-temperature primary cooling water is cooled in a state maintained at a predetermined high pressure by the pressurizer 16. It is sent to the steam generator 13 through the water pipe 14. In the steam generator 13, heat exchange is performed between the high-pressure and high-temperature primary cooling water and the secondary cooling water, and the cooled primary cooling water is returned to the pressurized water reactor 12 through the cooling water pipe 15.

  The steam generator 13 is connected to a steam turbine 17 via a cooling water pipe 18. The steam turbine 17 includes a high pressure turbine 19 and a low pressure turbine 20, and a generator 21 is connected to the steam generator 13. Further, a moisture separation heater 22 is provided between the high pressure turbine 19 and the low pressure turbine 20, and a cooling water branch pipe 23 branched from the cooling water pipe 18 is connected to the moisture separation heater 22. On the other hand, the high pressure turbine 19 and the moisture separation heater 22 are connected by a low temperature reheat pipe 24, and the moisture separation heater 22 and the low pressure turbine 20 are connected by a high temperature reheat pipe 25. Further, the low-pressure turbine 20 of the steam turbine 17 has a condenser 26, and a condenser pipe 26 and a drain pipe 28 for supplying and discharging cooling water (for example, seawater) are connected to the condenser 26. Yes. The condenser 26 is connected to a deaerator 30 through a cooling water pipe 29, and a condensate pump 31 and a low-pressure feed water heater 32 are provided in the cooling water pipe 29. The deaerator 30 is connected to the steam generator 13 via a cooling water pipe 33, and a water supply pump 34 and a high-pressure feed water heater 35 are provided in the cooling water pipe 33.

  Therefore, the steam generated by performing heat exchange with the high-pressure and high-temperature primary cooling water in the steam generator 13 is sent to the steam turbine 17 (from the high-pressure turbine 19 to the low-pressure turbine 20) through the cooling water pipe 18, and this steam is generated. Then, the steam turbine 17 is driven to generate power by the generator 21. At this time, the steam from the steam generator 13 drives the high pressure turbine 19, and then the moisture contained in the steam is removed and heated by the moisture separator / heater 22, and then the low pressure turbine 20 is driven. The steam that drives the steam turbine 17 is cooled by the condenser 26 to become condensed water, heated by the low-pressure feed water heater 32 by, for example, the low-pressure steam extracted from the low-pressure turbine 20, and dissolved by the deaerator 30. After impurities such as oxygen and uncondensed gas (ammonia gas) are removed, the high pressure feed water heater 35 heats the high pressure steam extracted from, for example, the high pressure turbine 19 and then returns to the steam generator 13.

  Further, in the pressurized water reactor 12, as shown in FIGS. 1 and 2, a reactor vessel (pressure vessel) 41 has a reactor vessel main body 42 and an upper portion thereof so that a reactor internal structure can be inserted therein. The reactor vessel lid 43 is openable and closable with respect to the reactor vessel main body 42. The reactor vessel main body 42 has a cylindrical shape with an upper portion opened and a lower portion closed in a spherical shape, and an inlet nozzle 44 and an outlet nozzle 45 for supplying and discharging light water (coolant) as primary cooling water are formed on the upper portion. Has been.

  As shown in detail in FIG. 2, four inlet nozzles 44 are formed, arranged at a predetermined angle A with respect to the 90 ° -270 ° center line, and at the 0 ° -180 ° center line. They are arranged at symmetrical positions. On the other hand, four outlet nozzles 45 are formed, arranged at a predetermined angle B with respect to the 0 ° -180 ° center line, and arranged at positions symmetrical with respect to the 90 ° -270 ° center line. ing.

  Within the reactor vessel main body 42, a cylindrical reactor core 46 having a cylindrical shape is disposed below the inlet nozzle 44 and the outlet nozzle 45 with a predetermined gap from the inner surface of the reactor vessel main body 42. An upper core plate 47 having a disk shape and a large number of communication holes (not shown) is connected to the upper portion of the slab, and a plurality of communication holes (similar to a disk shape and not shown) are formed at the bottom. A lower core plate 48 is connected. In the reactor vessel main body 42, an upper core support plate 49 having a disk shape is fixed above the core tank 46, and a plurality of core support rods 50 are connected to the upper core support plate 49 from the upper core support plate 49. The upper core plate 47, that is, the core tank 46 is supported by being suspended. On the other hand, the lower core plate 48, that is, the core tank 46 is positioned and held by a plurality of radial keys 52 with respect to the inner surface of the reactor vessel main body 42.

  A core 53 is formed by the core tank 46, the upper core plate 47, and the lower core plate 48, and a large number of fuel assemblies 54 are arranged in the core 53. Although not shown in the drawing, the fuel assembly 54 is configured by bundling a large number of fuel rods in a lattice shape 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 fuel assembly 54 has a control rod guide tube into which the control rod is inserted and an in-core instrumentation guide tube into which the in-core instrumentation detector is inserted, in addition to a large number of fuel rods. .

  A large number of control rod cluster guide tubes 55 are supported through the upper core support plate 49, and are extended from a control rod drive device (not shown) provided in the reactor vessel lid 43 so as to extend to the control rod cluster drive shaft. Is extended to the fuel assembly 54 through the control rod cluster guide tube 55, and the control rod is attached to the lower end. A number of in-core instrumentation guide pipes 56 are supported through the upper core support plate 49, and the lower end portion extends to the fuel assembly 54.

  Therefore, the control rod cluster drive shaft is moved by the control rod drive device and the control rod is inserted into the fuel assembly 54 to control the nuclear fission in the reactor core 53. The filled light water is heated, and hot light water is discharged from the outlet nozzle 45 and sent to the steam generator 13 as described above. That is, uranium or plutonium as the fuel constituting the fuel assembly 54 is fissioned to release neutrons, and the moderator and the light water as the primary cooling water reduce the kinetic energy of the released fast neutrons to produce thermal neutrons. And make it easier to cause new fission and take away the generated heat to cool. Further, by inserting the control rod into the fuel assembly 54, the number of neutrons generated in the core 53 is adjusted, and when the reactor is urgently stopped, it is rapidly inserted into the core 53.

  In the reactor vessel 41, an upper plenum 57 communicating with the outlet nozzle 45 is formed above the core 53, and a lower plenum 58 is formed below. A downcomer portion 59 that communicates with the inlet nozzle 44 and the lower plenum 57 is formed between the reactor vessel 41 and the reactor core 46. That is, the upper plenum 57 is formed by being divided into a core tank 46, an upper core support plate 49, and an upper core plate 47, and communicates with the outlet nozzle 45 and a large number of communication holes formed in the upper core plate 47. Communicating with the core 53 via The lower plenum 58 is formed by being divided into a lower core plate 48 and a reactor vessel main body 42 which are the bottom of the core tank 46, and communicates with the core 53 through a number of communication holes formed in the lower core plate 48. is doing. The downcomer portion 59 is formed by being partitioned on the side walls of the reactor vessel main body 42 and the reactor core 46, and the upper portion communicates with the inlet nozzle 44, while the lower portion communicates with the lower plenum 58.

  Accordingly, light water flows into the reactor vessel body 42 from the four inlet nozzles 44, flows down the downcomer portion 59 and reaches the lower plenum 58, and is guided upward by the spherical inner surface of the lower plenum 58. And then flows into the core 53 after passing through the lower core plate 48. The light water that has flowed into the core 53 absorbs heat energy generated from the fuel assemblies 54 constituting the core 53 to cool the fuel assemblies 54, while passing through the upper core plate 47 at a high temperature. Ascending to the upper plenum 57 and discharged through the outlet nozzle 45.

  In the present embodiment, as shown in FIGS. 3 and 4, a number of communication holes 61, 62, 63... Are formed in the lower core plate 48 to communicate the core 53 and the lower plenum 58. A perforated plate 71 is provided at the upper part of the lower core plate 48 as a flow resistance changing member for changing the flow resistance of light water flowing through the coolant supply communication holes 61, 62, 63. This flow resistance changing member sets the flow resistance of the communication hole formed at the center of the lower core plate 48 larger than the flow resistance of the communication hole formed on the outer peripheral side of the lower core plate 48. Specifically, a porous plate 71 is provided at the outlet of communication holes 61, 62, 63 formed in the center of the lower core plate 48.

  The perforated plate 71 is fixed (welded, bolted, etc.) to the distal end portion (upper end portion in FIG. 3) of the cylindrical support cylinder 72 in the axial direction. The lower end (in FIG. 3) is the upper surface of the lower core plate 48 and is fixed around the communication holes 61, 62, 63 to cover the outlet. The perforated plate 71 is made of mesh, punching metal, or the like. On the other hand, although not shown, the porous plate 71 is not provided for the communication hole formed on the outer peripheral side of the lower core plate 48.

  Accordingly, as shown in FIGS. 1 and 3, the light water that has flowed downward through the downcomer portion 59 and reached the lower plenum 58 is guided upward by the spherical inner surface of the lower plenum 58 and rises to reach the lower core. It passes through the plate 48 and flows into the core 53. At this time, light water that is guided upward by the inner surface of the lower plenum 58 rises at the center of the core 53 and decreases at the outer periphery. However, in this embodiment, the porous plate 71 is provided at the outlet of the communication holes 61, 62, 63 located at the center of the lower core plate 48, and the communication hole at the center of the communication hole at the outer periphery is provided. The flow resistance of 61, 62, 63 is large. Therefore, the light water that is guided upward by the inner surface of the lower plenum 58 has a large flow rate in the center, but resistance is generated when it passes through the communication holes 61, 62, and 63 by the porous plate 71. The flow rate of light water supplied from the lower plenum 58 to the core 53 is uniformly rectified in the radial direction of the core 53.

  As described above, according to the reactor of the first embodiment, the core tank 46 is arranged in the reactor vessel 41 having the inlet nozzle 44 and the outlet nozzle 45, and the core 53 is arranged in the core tank 46, while the lower core is arranged. The lower plenum 58 is defined by the plate 48 and the reactor vessel 41, and the downcomer portion 59 is defined by the side wall of the reactor vessel 41 and the core tank 46, and the core 53 and the lower plenum 58 are communicated with the lower core plate 48. A plurality of communication holes 61, 62, 63... And a perforated plate 71 for changing the flow resistance of light water flowing in the communication holes 61, 62, 63 located in the central portion above the lower core plate 48. Is provided.

  Accordingly, the light water introduced into the reactor vessel 41 from the inlet nozzle 44 descends the downcomer portion 59 to reach the lower plenum 58, and reverses and rises at the lower plenum 58 and passes through the lower core plate 48. As the flow rate increases to the core 53, the flow rate distribution of the rising light water is higher in the center of the lower plenum 58, but the perforated plate 71 is provided in the communication holes 61, 62, 63 in the center of the lower core plate 48. Therefore, the flow rate of light water flowing through the communication holes 61, 62, 63 is reduced, so that the flow rate of light water supplied to the core 53 is uniform with respect to the radial direction of the core 53. Thus, the heat exchange efficiency can be improved.

  Further, in the nuclear reactor of the first embodiment, a porous plate 71 is provided at the outlet of communication holes 61, 62, 63 formed in the center of the lower core plate 48 as a flow resistance changing member. Therefore, attachment and removal of the perforated plate 71 with respect to the communication holes 61, 62, and 63 are facilitated, and workability can be improved.

  FIG. 6 is a longitudinal sectional view showing a perforated plate provided in the pressurized water reactor according to the second embodiment of the present invention. The overall configuration of the nuclear reactor of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and the same members having the same functions as those described in this embodiment will be described. A duplicate description will be omitted.

  In the nuclear reactor of the second embodiment, as shown in FIGS. 1 and 6, a large number of communication holes 61, 62, 63... Are formed in the lower core plate 48 to communicate the core 53 and the lower plenum 58. The communication hole 61 side is the center side of the lower core plate 48, and the communication hole 63 side is the outer peripheral side of the lower core plate 48. And perforated plate 81, 82, 83 ... is provided in the upper part of the lower core plate 48 as a flow resistance change member which changes the flow resistance of the light water which flows through the communicating holes 61, 62, 63 .... . This flow resistance changing member sets the flow resistance of the communication hole formed at the center of the lower core plate 48 larger than the flow resistance of the communication hole formed on the outer peripheral side of the lower core plate 48. Specifically, porous plates 81, 82, 83 having different heights are provided at the outlets of the communication holes 61, 62, 63 formed in the center of the lower core plate 48.

The perforated plates 81, 82, 83 are fixed to the distal ends in the axial direction of the cylindrical support cylinders 84, 85, 86, and the base ends in the axial direction of the support cylinders 84, 85, 86 are lower. It is the upper surface of the core plate 48 and is fixed around the communication holes 61, 62, 63, thereby covering the outlet portion. The length of the support tube 86 of the communication hole 63 formed on the outer peripheral side of the lower core plate 48 is set longer than the support tube 84 of the communication hole 61 formed on the center side of the lower core plate 48. The heights H ₁ , H from the upper surface of the lower core plate 48 to the perforated plates 81, 82, 83 with respect to the communication holes 61, 62, 63 aligned from the center side to the outer peripheral side of the lower core plate 48. _{2, H 3} is gradually increased.

  Accordingly, the light water flowing down the downcomer portion 59 and reaching the lower plenum 58 rises while being guided upward by the spherical inner surface of the lower plenum 58, passes through the lower core plate 48, and flows into the core 53. To do. At this time, light water that is guided upward by the inner surface of the lower plenum 58 rises at the center of the core 53 and decreases at the outer periphery. However, in the present embodiment, the perforated plates 81, 82, 83 having different heights are provided at the outlets of the communication holes 61, 62, 63 located at the center of the lower core plate 48. On the other hand, the flow resistance of the communication holes 61, 62, 63 at the center is gradually increased. Therefore, although the light water that is guided upward by the inner surface of the lower plenum 58 has a large flow rate at the center, resistance is generated when it passes through the communication holes 61, 62, 63 by the perforated plates 81, 82, 83. As a result, the flow rate of light water supplied from the lower plenum 58 to the core 53 is uniformly rectified with respect to the radial direction of the core 53.

  As described above, according to the nuclear reactor of the second embodiment, the lower core plate 48 is formed with a large number of communication holes 61, 62, 63... For communicating the core 53 and the lower plenum 58. Perforated plates 81, 82, and 83 having different heights that change the flow resistance of light water flowing through the communication holes 61, 62, and 63 located in the upper center portion are provided.

  Accordingly, the light water introduced into the reactor vessel 41 from the inlet nozzle 44 descends the downcomer portion 59 to reach the lower plenum 58, and reverses and rises at the lower plenum 58 and passes through the lower core plate 48. When rising to the core 53, the flow distribution of the rising light water is higher in the center of the lower plenum 58, but the communication holes 61, 62, and 63 in the center of the lower core plate 48 have different heights. Since the plates 81, 82, 83 are provided, the flow rate of light water flowing through the communication holes 61, 62, 63 is reduced toward the center, so that the flow rate of light water supplied to the core 53 is reduced. Therefore, the heat exchange efficiency can be improved.

  In the nuclear reactor of the second embodiment, the height of the porous plate 81 provided in the communication hole 61 located on the center side of the lower core plate 48 is set to the height of the porous plate 83 provided in the communication hole 63 located on the outer peripheral side. It is set lower than the height. Therefore, the flow resistance of the communication holes 61, 62, 63 can be finely adjusted by the height of the perforated plates 81, 82, 83, and the structure can be simplified and the cost can be reduced.

  FIG. 7 is a longitudinal sectional view showing a perforated plate provided in a pressurized water reactor according to Embodiment 3 of the present invention. The overall configuration of the nuclear reactor of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and the same members having the same functions as those described in this embodiment will be described. A duplicate description will be omitted.

  In the nuclear reactor of the third embodiment, as shown in FIGS. 1 and 7, a plurality of communication holes 61, 62, 63... Are formed in the lower core plate 48 to communicate the core 53 and the lower plenum 58. A perforated plate 71 is provided below the lower core plate 48 as a flow resistance changing member for changing the flow resistance of light water flowing through the communication holes 61, 62, 63. This flow resistance changing member sets the flow resistance of the communication hole formed at the center of the lower core plate 48 larger than the flow resistance of the communication hole formed on the outer peripheral side of the lower core plate 48. Specifically, a porous plate 71 is provided at the inlet of communication holes 61, 62, 63 formed in the center of the lower core plate 48.

  The perforated plate 71 is fixed to the distal end portion (lower end portion in FIG. 7) of the support cylinder 72, and the base end portion (upper end portion in FIG. 7) of the support cylinder 72 is the lower surface of the lower core plate 48. And it fixes to the circumference | surroundings of the communicating holes 61, 62, 63, and has coat | covered the inlet part.

  Accordingly, the light water flowing down the downcomer portion 59 and reaching the lower plenum 58 rises while being guided upward by the spherical inner surface of the lower plenum 58 and flows into the core 53 through the lower core plate 48. To do. At this time, light water that is guided upward by the inner surface of the lower plenum 58 rises at the center of the core 53 and decreases at the outer periphery. However, in this embodiment, the porous plate 71 is provided at the inlet of the communication holes 61, 62, 63 located at the center of the lower core plate 48, and the communication hole at the center of the communication hole at the outer periphery is provided. The flow resistance of 61, 62, 63 is large. Therefore, the light water that is guided upward by the inner surface of the lower plenum 58 has a large flow rate in the center, but resistance is generated when it passes through the communication holes 61, 62, and 63 by the porous plate 71. The flow rate of light water supplied from the lower plenum 58 to the core 53 is uniformly rectified in the radial direction of the core 53.

  As described above, according to the nuclear reactor of the third embodiment, the lower core plate 48 is formed with a large number of communication holes 61, 62, 63... For communicating the core 53 and the lower plenum 58. A perforated plate 71 for changing the flow resistance of light water flowing in the communication holes 61, 62, 63 located in the central portion of the lower portion is provided.

  Accordingly, the light water introduced into the reactor vessel 41 from the inlet nozzle 44 descends the downcomer portion 59 to reach the lower plenum 58, and reverses and rises at the lower plenum 58 and passes through the lower core plate 48. As the flow rate increases to the core 53, the flow rate distribution of the rising light water is higher in the center of the lower plenum 58, but the perforated plate 71 is provided in the communication holes 61, 62, 63 in the center of the lower core plate 48. Therefore, the flow rate of light water flowing through the communication holes 61, 62, 63 is reduced, so that the flow rate of light water supplied to the core 53 is adjusted to be uniform with respect to the radial direction of the core. As a result, the heat exchange efficiency can be improved.

  FIG. 8 is a longitudinal sectional view showing a perforated plate provided in a pressurized water reactor according to Example 4 of the present invention. The overall configuration of the nuclear reactor of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and the same members having the same functions as those described in this embodiment will be described. A duplicate description will be omitted.

  In the nuclear reactor of the fourth embodiment, as shown in FIGS. 1 and 8, a plurality of communication holes 61, 62, 63... Are formed in the lower core plate 48 to communicate the core 53 and the lower plenum 58. The communication hole 61 side is the center side of the lower core plate 48, and the communication hole 63 side is the outer peripheral side of the lower core plate 48. And the lower core plate 48 is provided with perforated plates 81, 82, 83... As flow resistance changing members for changing the flow resistance of light water flowing through the communication holes 61, 62, 63. . This flow resistance changing member sets the flow resistance of the communication hole formed at the center of the lower core plate 48 larger than the flow resistance of the communication hole formed on the outer peripheral side of the lower core plate 48. Specifically, porous plates 81, 82, 83 having different heights are provided at the inlets of the communication holes 61, 62, 63 formed in the center of the lower core plate 48.

The perforated plates 81, 82, 83 are fixed to the distal ends of the support cylinders 84, 85, 86, and the base ends of the support cylinders 84, 85, 86 are the lower surfaces of the lower core plate 48 and communicate with each other. By fixing around the holes 61, 62, 63, the inlet portion is covered. The length of the support tube 86 of the communication hole 63 formed on the outer peripheral side of the lower core plate 48 is set longer than the support tube 84 of the communication hole 61 formed on the center side of the lower core plate 48. The heights H ₁ , H from the lower surface of the lower core plate 48 to the perforated plates 81, 82, 83 with respect to the communication holes 61, 62, 63 aligned from the center side to the outer peripheral side of the lower core plate 48. _{2, H 3} is gradually increased.

  Accordingly, the light water flowing down the downcomer portion 59 and reaching the lower plenum 58 rises while being guided upward by the spherical inner surface of the lower plenum 58 and flows into the core 53 through the lower core plate 48. To do. At this time, light water that is guided upward by the inner surface of the lower plenum 58 rises at the center of the core 53 and decreases at the outer periphery. However, in the present embodiment, the perforated plates 81, 82, 83 having different heights are provided at the inlets of the communication holes 61, 62, 63 located at the center of the lower core plate 48, and the communication holes in the outer peripheral part are provided. On the other hand, the flow resistance of the communication holes 61, 62, 63 at the center is gradually increased. Therefore, although the light water that is guided upward by the inner surface of the lower plenum 58 has a large flow rate at the center, resistance is generated when it passes through the communication holes 61, 62, 63 by the perforated plates 81, 82, 83. As a result, the flow rate of light water supplied from the lower plenum 58 to the core 53 is uniformly rectified with respect to the radial direction of the core 53.

  As described above, according to the nuclear reactor of the fourth embodiment, the lower core plate 48 is formed with a large number of communication holes 61, 62, 63... For communicating the core 53 and the lower plenum 58. Perforated plates 81, 82, 83 having different heights for changing the flow resistance of light water flowing through the communication holes 61, 62, 63 located in the central portion are provided at the bottom.

  Accordingly, the light water introduced into the reactor vessel 41 from the inlet nozzle 44 descends the downcomer portion 59 to reach the lower plenum 58, and reverses and rises at the lower plenum 58 and passes through the lower core plate 48. The flow rate distribution of the rising light water rises at the center of the lower plenum 58, but the perforated plates having different heights in the communication holes 61, 62, 63 in the center of the lower core plate 48. Since 81, 82, and 83 are provided, the flow rate of light water flowing through the communication holes 61, 62, and 63 is reduced toward the center, so that the flow rate of light water supplied to the core 53 is reduced in the core 53. It will be adjusted so that it may become uniform with respect to a radial direction, and the improvement of heat exchange efficiency can be aimed at.

  In Examples 2 and 4 described above, the flow resistance of the communication holes 61, 62, 63 was changed by providing the porous plates 81, 82, 83 having different heights, but the aperture ratio of the porous plate was changed. That is, the aperture ratio of the porous plate provided in the communication hole 61 positioned on the center side of the lower core plate 48 is set lower than the aperture ratio of the porous plate 83 provided in the communication hole 63 positioned on the outer peripheral side. Also good.

  FIG. 9 is a longitudinal sectional view showing a perforated plate provided in a pressurized water reactor according to Example 5 of the present invention. The overall configuration of the nuclear reactor of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and the same members having the same functions as those described in this embodiment will be described. A duplicate description will be omitted.

  In the nuclear reactor of the fifth embodiment, as shown in FIGS. 1 and 9, a large number of communication holes 61, 62, 63... Are formed in the lower core plate 48 to communicate the core 53 and the lower plenum 58. A perforated plate 91 is provided below the lower core plate 48 as a flow resistance changing member for changing the flow resistance of light water flowing through the communication holes 61, 62, 63. This flow resistance changing member sets the flow resistance of the communication hole formed at the center of the lower core plate 48 larger than the flow resistance of the communication hole formed on the outer peripheral side of the lower core plate 48. Specifically, a porous plate 91 is provided at the inlet of communication holes 61, 62, 63 formed in the center of the lower core plate 48.

  The perforated plate 91 is fixed to the distal end portion of the support cylinder 92, and the base end portion of the support cylinder 92 is the lower surface of the lower core plate 48 and is fixed around the communication holes 61, 62, and 63. Thus, the inlet portion is covered. The support tube 92 is formed with a flow path 92a penetrating inside and outside.

  Accordingly, the light water flowing down the downcomer portion 59 and reaching the lower plenum 58 rises while being guided upward by the spherical inner surface of the lower plenum 58, passes through the lower core plate 48, and flows into the core 53. To do. At this time, light water that is guided upward by the inner surface of the lower plenum 58 rises at the center of the core 53 and decreases at the outer periphery. However, in this embodiment, the porous plate 91 is provided at the inlet of the communication holes 61, 62, 63 located at the center of the lower core plate 48, and the communication hole at the center of the communication hole at the outer periphery is provided. The flow resistance of 61, 62, 63 is large. Therefore, although the light water that rises while being guided upward by the inner surface of the lower plenum 58 has a large flow rate at the center, resistance is generated when it passes through the communication holes 61, 62, 63 by the porous plate 91 and the support cylinder 92. . In this case, since the flow path 92 a is formed in the support cylinder 92, the flow resistance of the communication hole 63 on the outer peripheral side is smaller than that of the communication hole 61 on the center side. As a result, the core 53 is connected to the core 53 from the lower plenum 58. The flow rate of the light water supplied to the rectifier is uniformly rectified with respect to the radial direction of the core 53.

  As described above, according to the reactor of the fifth embodiment, the lower core plate 48 is formed with a large number of communication holes 61, 62, 63... For communicating the core 53 and the lower plenum 58. A perforated plate 91 for changing the flow resistance of light water flowing in the communication holes 61, 62, 63 located in the center of the perforated plate 91 is provided, and a passage 92a is provided in a support cylinder 92 that supports the perforated plate 91.

  Accordingly, the light water introduced into the reactor vessel 41 from the inlet nozzle 44 descends the downcomer portion 59 to reach the lower plenum 58, and reverses and rises at the lower plenum 58 and passes through the lower core plate 48. As the flow rate rises to the core 53, the flow rate distribution of the rising light water is higher in the central portion of the lower plenum 58, but the perforated plate 91 and the passage are formed in the communication holes 61, 62, 63 in the central portion of the lower core plate 48. Since the support cylinder 92 having 92 a is provided, the flow rate of light water flowing through the communication holes 61, 62, 63 is reduced, so that the flow rate of light water supplied to the core 53 is changed in the radial direction of the core 53. Therefore, the heat exchange efficiency can be improved.

  In the nuclear reactor of the fifth embodiment, the perforated plate 91 is attached to the lower surface of the lower core plate 48 via the support cylinder 92, and a flow path 92 a is formed in the support cylinder 92. Therefore, light water flows not only through the holes of the perforated plate 91 but also through the flow passages 92a of the support cylinder 92 into the communication holes 61, 62, 63, so that the light water can be easily guided to the core 53 side, and the flow resistance adjustment allowance is increased. Can be secured sufficiently.

  FIG. 10 is a longitudinal sectional view showing a perforated plate provided in a pressurized water reactor according to Example 6 of the present invention. The overall configuration of the nuclear reactor of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and the same members having the same functions as those described in this embodiment will be described. A duplicate description will be omitted.

  In the nuclear reactor of the sixth embodiment, as shown in FIGS. 1 and 10, a plurality of communication holes 61, 62, 63... Are formed in the lower core plate 48 to communicate the core 53 and the lower plenum 58. The communication hole 61 side is the center side of the lower core plate 48, and the communication hole 63 side is the outer peripheral side of the lower core plate 48. And the lower core plate 48 is provided with perforated plates 101, 102, 103... As flow resistance changing members for changing the flow resistance of light water flowing through the communication holes 61, 62, 63. . This flow resistance changing member sets the flow resistance of the communication hole formed at the center of the lower core plate 48 larger than the flow resistance of the communication hole formed on the outer peripheral side of the lower core plate 48. Specifically, porous plates 101, 102, and 103 having different heights are provided at the inlets of communication holes 61, 62, and 63 formed in the center of the lower core plate 48.

  The perforated plates 101, 102, 103 are fixed to the lower surface of the lower core plate 48 through support cylinders 104, 105, 106 and around the communication holes 61, 62, 63 to cover the inlet portion. . The length of the support tube 106 of the communication hole 63 formed on the outer peripheral side of the lower core plate 48 is set longer than the support tube 104 of the communication hole 61 formed on the center side of the lower core plate 48. ing. The support cylinders 104, 105, and 106 are formed with flow paths 104a, 105a, and 106a penetrating inside and outside.

  Accordingly, the light water flowing down the downcomer portion 59 and reaching the lower plenum 58 rises while being guided upward by the spherical inner surface of the lower plenum 58, passes through the lower core plate 48, and flows into the core 53. To do. At this time, light water that is guided upward by the inner surface of the lower plenum 58 rises at the center of the core 53 and decreases at the outer periphery. However, in this embodiment, the perforated plates 101, 102, and 103 having different heights are provided at the inlets of the communication holes 61, 62, and 63 located in the center of the lower core plate 48, and the communication holes in the outer peripheral portion are provided. On the other hand, the flow resistance of the communication holes 61, 62, 63 at the center is gradually increased. For this reason, the light water that rises while being guided upward by the inner surface of the lower plenum 58 has a large flow rate at the center, but the communication holes 61, 62, 63 are formed by the perforated plates 101, 102, 103 and the support cylinders 104, 105, 106. Resistance occurs when passing. In this case, since the flow paths 104a, 105a, and 106a are formed in the support cylinders 104, 105, and 106, the flow resistance of the communication hole 63 on the outer peripheral side is smaller than that of the communication hole 61 on the center side. As a result, the flow rate of light water supplied from the lower plenum 58 to the core 53 is uniformly rectified in the radial direction of the core 53.

  As described above, according to the reactor of the sixth embodiment, the lower core plate 48 is formed with a large number of communication holes 61, 62, 63... For communicating the core 53 and the lower plenum 58. Are provided with perforated plates 101, 102, 103 having different heights for changing the flow resistance of light water flowing through the communication holes 61, 62, 63 located in the center, and supporting the perforated plates 101, 102, 103 The cylinders 104, 105, 106 are provided with flow paths 104a, 105a, 106a.

  Accordingly, the light water introduced into the reactor vessel 41 from the inlet nozzle 44 descends the downcomer portion 59 to reach the lower plenum 58, and reverses and rises at the lower plenum 58 and passes through the lower core plate 48. When rising to the core 53, the flow distribution of the rising light water is higher in the center of the lower plenum 58, but the communication holes 61, 62, and 63 in the center of the lower core plate 48 have different heights. Since the support cylinders 104, 105, 106 having the plates 101, 102, 103 and the flow paths 104a, 105a, 106a are provided, the flow rate of light water flowing through the communication holes 61, 62, 63 decreases toward the center side. As a result, the flow rate of light water supplied to the core 53 is adjusted to be uniform with respect to the radial direction of the core 53, and the heat exchange efficiency can be improved.

  Further, in the nuclear reactor of the sixth embodiment, the perforated plates 101, 102, 103 are attached to the lower surface of the lower core plate 48 through the support cylinders 104, 105, 106, and the flow paths 104a, 104 are connected to the support cylinders 101, 102, 103, respectively. 105a and 106a are formed. Accordingly, light water flows into the communication holes 61, 62, 63 not only through the holes of the perforated plates 101, 102, 103 but also through the flow paths 104 a, 105 a, 106 a of the support cylinders 104, 105, 106. It is easy to guide to the side, and a sufficient allowance for adjusting the flow resistance can be secured.

  FIG. 11 is a longitudinal sectional view showing a perforated plate provided in a pressurized water reactor according to Example 7 of the present invention, and FIG. 12 is a perspective view showing the perforated plate of Example 7 and a support tube. The overall configuration of the nuclear reactor of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and the same members having the same functions as those described in this embodiment will be described. A duplicate description will be omitted.

  In the reactor of the seventh embodiment, as shown in FIGS. 1, 11, and 12, the lower core plate 48 is formed with a large number of communication holes 61 that connect the core 53 and the lower plenum 58, and the lower core plate. A perforated plate 111 is provided as a flow resistance changing member that changes the flow resistance of the light water flowing in the communication hole 61 at the lower portion of 48. The porous plate 111 is fixed to the lower surface of the lower core plate 48 through the support cylinder 112 so as to cover the inlet portion of the communication hole 61. The support cylinder 112 is formed with a slit-shaped passage 112 a on the center side of the lower core plate 48.

  Accordingly, the light water flowing down the downcomer portion 59 and reaching the lower plenum 58 rises while being guided upward by the spherical inner surface of the lower plenum 58 and flows into the core 53 through the lower core plate 48. To do. At this time, light water that is guided upward by the inner surface of the lower plenum 58 rises at the center of the core 53 and decreases at the outer periphery. However, in this embodiment, the porous plate 111 is provided at the inlet of the communication hole 61 located at the center of the lower core plate 48, and a passage 112 a facing the center of the lower core plate 48 is formed in the support cylinder 112. Yes. Therefore, the light water that rises while being guided upward by the inner surface of the lower plenum 58 has a large flow rate in the center portion, but resistance is generated when passing through the communication hole 61 by the porous plate 111 and the support cylinder 112. The flow rate of light water supplied from the lower plenum 58 to the core 53 is uniformly rectified in the radial direction of the core 53.

  As described above, according to the reactor of the seventh embodiment, the lower core plate 48 is formed with a large number of communication holes 61 for communicating the core 53 and the lower plenum 58, and the lower core plate 48 is connected to the central portion. A perforated plate 111 that changes the flow resistance of light water flowing in the hole 61 is provided, and a passage 112 a that faces the center side of the lower core plate 48 is provided in the support cylinder 12 that supports the perforated plate 111.

  Accordingly, the light water introduced into the reactor vessel 41 from the inlet nozzle 44 descends the downcomer portion 59 to reach the lower plenum 58, and reverses and rises at the lower plenum 58 and passes through the lower core plate 48. In this case, the flow distribution of the rising light water becomes higher in the central portion of the lower plenum 58, but the support hole having the porous plate 111 and the passage 112a in the communication hole 61 in the central portion of the lower core plate 48. Since the cylinder 112 is provided, the flow rate of light water flowing through the communication hole 61 is reduced, so that the flow rate of light water supplied to the core 53 is uniform with respect to the radial direction of the core 53. Thus, the heat exchange efficiency can be improved.

  Further, in the nuclear reactor of the seventh embodiment, the porous plate 111 is attached to the lower surface of the lower core plate 48 via the support cylinder 112, and the flow path 112 a facing the center side of the lower core plate 48 is formed in the support cylinder 112. Yes. Accordingly, light water flows into the communication hole 61 not only through the hole of the perforated plate 111 but also through the flow path 112a of the support cylinder 112, and it becomes easy to guide the light water to the reactor core 53 side, and a sufficient allowance for flow resistance adjustment is ensured. can do.

  FIG. 13 is a longitudinal sectional view showing a perforated plate provided in a pressurized water reactor according to Example 8 of the present invention. The overall configuration of the nuclear reactor of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and the same members having the same functions as those described in this embodiment will be described. A duplicate description will be omitted.

  In the nuclear reactor of the eighth embodiment, as shown in FIGS. 1 and 13, a porous plate 111 is provided as a flow resistance changing member for changing the flow resistance of light water flowing in the communication hole 61 at the lower part of the lower core plate 48. ing. The perforated plate 111 is fixed to the lower surface of the lower core plate 48 through the support cylinder 112 so as to cover the inlet portion of the communication hole 61, and the support cylinder 112 is connected to the center side of the lower core plate 48. A slit-shaped passage 112a facing is formed. Inside the perforated plate 111 and the support cylinder 112, an inner cylinder 115 is mounted via a spacer 114, and a large number of flow paths 115a are formed in the inner cylinder 115.

  Therefore, although the light water rising from the lower plenum 58 has a large flow rate at the center, resistance is generated when passing through the communication hole 61 by the perforated plate 111, the support cylinder 112, and the inner cylinder 115, and the core 53 The flow rate of the light water supplied to the rectifier is uniformly rectified with respect to the radial direction of the core 53.

  As described above, according to the reactor of the eighth embodiment, a large number of communication holes 61 for communicating the core 53 and the lower plenum 58 are formed in the lower core plate 48, and the communication located in the central portion is formed below the lower core plate 48. A perforated plate 111 for changing the flow resistance of light water flowing in the hole 61 is provided, and a passage 115a facing the center side of the lower core plate 48 is provided in the support cylinder 112 that supports the perforated plate 111, and the perforated plate 111 and the support An inner cylinder 115 having a large number of flow paths 115 a is provided inside the cylinder 112.

  Accordingly, the light water introduced into the reactor vessel 41 from the inlet nozzle 44 descends the downcomer portion 59 to reach the lower plenum 58, and reverses and rises at the lower plenum 58 and passes through the lower core plate 48. In this case, the flow rate distribution of the rising light water becomes higher at the center of the lower plenum 58, but the support hole 61 has the porous plate 111 and the passage 115a in the communication hole 61 in the center of the lower core plate 48. Since the cylinder 112 and the inner cylinder 115 are provided, the flow rate of light water flowing through the communication hole 61 is reduced, so that the flow rate of light water supplied to the core 53 is uniform with respect to the radial direction of the core 53. Thus, the heat exchange efficiency can be improved.

  Further, in the nuclear reactor of the eighth embodiment, the perforated plate 111 is attached to the lower surface of the lower core plate 48 via the support cylinder 112, and the inner cylinder 115 is provided inside thereof. Accordingly, light water flows into the communication hole 61 not only through the hole of the perforated plate 111 but also through the passage 115a of the inner cylinder 115, and the flow resistance is adjusted in two stages. A sufficient amount of resistance adjustment can be secured.

  FIG. 14 is a longitudinal sectional view showing a perforated plate provided in a pressurized water reactor according to Example 9 of the present invention. The overall configuration of the nuclear reactor of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and the same members having the same functions as those described in this embodiment will be described. A duplicate description will be omitted.

  In the nuclear reactor of the ninth embodiment, as shown in FIGS. 1 and 14, a large number of communication holes 61, 62... That connect the core 53 and the lower plenum 58 are formed in the lower core plate 48. The side is the center side of the lower core plate 48, and the communication hole 62 side is the outer peripheral side of the lower core plate 48. Perforated plates 121, 122,... Are provided as flow resistance changing members for changing the flow resistance of light water flowing through the communication holes 61, 62,. This flow resistance changing member sets the flow resistance of the communication hole formed at the center of the lower core plate 48 larger than the flow resistance of the communication hole formed on the outer peripheral side of the lower core plate 48. Specifically, the porous plates 121 and 122 are provided at the outlets of the communication holes 61 and 62 formed in the center of the lower core plate 48.

  The perforated plates 121 and 122 are fixed to the periphery of the communication holes 61 and 62 on the upper surface of the lower core plate 48 via the support cylinders 123 and 124, thereby covering the outlet portions. Adjustment holes 121a and 122a are formed in the center of the perforated plates 121 and 122, and plug members (opening ratio adjustment members) 125 and 126 are fitted into the adjustment holes 121a and 122a so as to be movable up and down. is doing. The plug members 125 and 126 can adjust the aperture ratios of the porous plates 121 and 122 by changing the fitting amounts of the porous plates 121 and 122 into the adjustment holes 121a and 122a. In this embodiment, the fitting amounts of the plug members 125 and 126 are such that the aperture ratio of the porous plate 121 located on the center side of the lower core plate 48 is lower than the aperture ratio of the porous plate 122 located on the outer peripheral side. Has been adjusted.

  Therefore, although the light water rising from the lower plenum 58 has a large flow rate in the center, resistance is generated when it passes through the communication holes 61 and 62 by the porous plates 121 and 122, and is supplied from the lower plenum 58 to the core 53. The light water flow rate is uniformly rectified in the radial direction of the core 53.

  As described above, according to the nuclear reactor of the ninth embodiment, the porous plates 121 and 122 for changing the flow resistance of the light water flowing in the communication holes 61 and 62 located in the central portion are provided on the upper portion of the lower core plate 48. By fitting the plug members 125 and 126, the aperture ratio can be adjusted.

  Accordingly, the light water introduced into the reactor vessel 41 from the inlet nozzle 44 descends the downcomer portion 59 to reach the lower plenum 58, and reverses and rises at the lower plenum 58 and passes through the lower core plate 48. As the flow rate rises to the core 53, the flow rate distribution of the rising light water is higher in the central portion of the lower plenum 58, but the perforated plate 121 having different opening ratios in the communication holes 61 and 62 in the central portion of the lower core plate 48. , 122 are provided, the flow rate of light water flowing through the communication holes 61, 62 is reduced toward the center side, so that the flow rate of light water supplied to the core 53 is relative to the radial direction of the core 53. It will be adjusted so that it may become uniform and the heat exchange efficiency can be improved.

  Further, in the nuclear reactor of the ninth embodiment, the aperture ratio of the porous plates 121 and 122 can be adjusted by changing the fitting amounts of the porous plates 121 and 122 by the plug members 125 and 126. Therefore, the flow rate of the light water supplied to the core 53 can be easily adjusted by adjusting the aperture ratio of the porous plates 121 and 122 according to the flow distribution of the light water in the lower plenum 58.

  FIG. 15 is a longitudinal sectional view showing a porous plate provided in a pressurized water reactor according to Example 10 of the present invention. The overall configuration of the nuclear reactor of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and the same members having the same functions as those described in this embodiment will be described. A duplicate description will be omitted.

  In the nuclear reactor of the tenth embodiment, as shown in FIGS. 1 and 15, the perforated plates 121, 122, which change the flow resistance of light water flowing in the communication holes 61, 62... Below the lower core plate 48.・ ・ Is provided. The perforated plates 121 and 122 are fixed around the communication holes 61 and 62 on the lower surface of the lower core plate 48 via support cylinders 123 and 124. Adjustment holes 121a and 122a are formed in the center of the perforated plates 121 and 122, and plug members 125 and 126 are fitted in the adjustment holes 121a and 122a so as to be movable up and down. The plug members 125 and 126 have a truncated cone shape, and the opening ratios of the porous plates 121 and 122 can be adjusted by changing the fitting amounts of the porous plates 121 and 122 into the adjustment holes 121a and 122a. .

  Therefore, although the light water rising from the lower plenum 58 has a large flow rate in the center, resistance is generated when it passes through the communication holes 61 and 62 by the porous plates 121 and 122, and is supplied from the lower plenum 58 to the core 53. The light water flow rate is uniformly rectified in the radial direction of the core 53. Further, the light water in the lower plenum 58 is guided to the inclined surfaces (side surfaces) of the plug members 125 and 126 and introduced into the communication holes 61 and 62 from the porous plates 121 and 122, and the amount of introduction can be adjusted. it can.

  As described above, according to the reactor of the tenth embodiment, the perforated plates 121 and 122 for changing the flow resistance of the light water flowing in the communication holes 61 and 62 located in the central portion are provided on the upper portion of the lower core plate 48. By fitting the plug members 125 and 126, the aperture ratio can be adjusted. Accordingly, the flow rate of light water flowing through the communication holes 61 and 62 is reduced toward the center by the porous plates 121 and 122 having different opening ratios, so that the flow rate of light water supplied to the core 53 is increased in the radial direction of the core 53. On the other hand, it is adjusted to be uniform, so that the heat exchange efficiency can be improved.

  In Examples 9 and 10 described above, the plug members 125 and 126 that adjust the aperture ratios of the porous plates 121 and 122 are rigid bodies or elastic bodies, but may be porous bodies.

  FIG. 16 is a longitudinal sectional view showing a perforated plate provided in a pressurized water reactor according to Example 11 of the present invention, and FIG. 17 is a plan view of a guide member of Example 11. The overall configuration of the nuclear reactor of the present embodiment is substantially the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and the same members having the same functions as those described in this embodiment will be described. A duplicate description will be omitted.

  In the nuclear reactor of the eleventh embodiment, as shown in FIGS. 1, 16 and 17, a large number of communication holes... 68, 69 for communicating the core 53 and the lower plenum 58 are formed in the lower core plate 48. The communication hole 68 side is the center side of the lower core plate 48, and the communication hole 69 side is the outer peripheral side of the lower core plate 48. In the lower part of the lower core plate 48, guide members 131, 132,... Are provided as flow resistance changing members for changing the flow resistance of light water flowing in the communication holes 68, 69 provided on the outer peripheral side thereof. ing. The guide members 131 and 132 are fixed around the communication holes 61 and 62 on the lower surface of the lower core plate 48. In this case, the guide members 131, 132 are fixed to the outer peripheral side of the lower core plate 48 in the communication holes 61, 62, and are inclined so that the height thereof becomes lower toward the center side of the lower core plate 48. The guide member 132 of the communication hole 69 formed on the outer peripheral side of the lower core plate 48 is set higher than the guide member 131 of the communication hole 68 formed on the center side of the lower core plate 48. ing.

  Therefore, the light water rising from the lower plenum 58 has a large flow rate at the center and flows to the outer peripheral side along the lower surface of the lower core plate 48 and is guided by the guide members 131 and 132 to communicate with the outer peripheral side communication holes 68 and 69. Therefore, the flow rate of light water supplied from the lower plenum 58 to the core 53 is uniformly rectified with respect to the radial direction of the core 53.

  As described above, according to the reactor of the eleventh embodiment, the guide members 131 and 132 for introducing light water into the communication holes 68 and 69 located in the outer peripheral portion are provided below the lower core plate 48. Therefore, light water can be positively introduced by the guide members 131 and 132 into the communication holes 68 and 69 on the outer peripheral portion side where light water does not easily flow, and the flow rate of light water supplied to the core 53 is the diameter of the core 53. It is adjusted to be uniform with respect to the direction, and the heat exchange efficiency can be improved.

  In each of the above-described embodiments, a perforated plate or a guide member as a flow resistance changing member is provided for the communication holes 61, 62, 63 in the central portion of the lower core plate 48, or the communication hole 68 on the outer peripheral side. , 69 may be provided in all the communication holes 61, 62, 63... 68, 69, and the flow resistance may be changed by changing the aperture ratio.

  In each of the above-described embodiments, the support cylinder is provided below or above the lower core plate 48 provided at the lower part of the fuel assembly 54. In short, the present invention provides a communication hole for the fuel assembly 54. A flow resistance member may be provided at the inlet (upstream side). Further, a flow resistance member may be provided at the outlet (downstream side) of the communication hole of the fuel assembly 54.

  The present invention comprises a nuclear reactor containment vessel, a pressure vessel accommodated in the nuclear reactor containment vessel, and a coolant supply piping system for supplying a coolant into the pressure vessel. The present invention is applicable to a nuclear reactor that generates steam by heat exchange and generates power by driving a power generation turbine with the generated steam, and is not limited to the above-described pressurized water reactor (PWR), but other types of nuclear reactors such as boiling water It can also be applied to a mold furnace (BWR). That is, in the nuclear reactor according to the present invention, the flow resistance changing member for changing the flow resistance of the coolant flowing in the communication hole is provided at the upper or lower portion of the core plate, so that the coolant is supplied from the lower plenum to the core. It supplies uniformly in radial direction and circumferential direction, and can be applied to any kind of nuclear reactor.

It is a schematic block diagram showing the internal structure of the pressurized water reactor which concerns on Example 1 of this invention. It is II-II sectional drawing of FIG. 3 is a cross-sectional view of a lower core plate of Example 1. FIG. 2 is a plan view of a perforated plate fixed to a lower core plate of Example 1. FIG. 1 is a schematic configuration diagram of a nuclear power plant having a pressurized water reactor of Example 1. FIG. It is a longitudinal cross-sectional view showing the perforated plate provided in the pressurized water reactor which concerns on Example 2 of this invention. It is a longitudinal cross-sectional view showing the perforated plate provided in the pressurized water reactor which concerns on Example 3 of this invention. It is a longitudinal cross-sectional view showing the perforated plate provided in the pressurized water reactor which concerns on Example 4 of this invention. It is a longitudinal cross-sectional view showing the perforated plate provided in the pressurized water reactor which concerns on Example 5 of this invention. It is a longitudinal cross-sectional view showing the perforated plate provided in the pressurized water reactor which concerns on Example 6 of this invention. It is a longitudinal cross-sectional view showing the perforated plate provided in the pressurized water reactor which concerns on Example 7 of this invention. It is a perspective view showing the perforated plate and the support tube of Example 7. It is a longitudinal cross-sectional view showing the perforated plate provided in the pressurized water reactor which concerns on Example 8 of this invention. It is a longitudinal cross-sectional view showing the perforated plate provided in the pressurized water reactor which concerns on Example 9 of this invention. It is a longitudinal cross-sectional view showing the perforated plate provided in the pressurized water reactor which concerns on Example 10 of this invention. It is a longitudinal cross-sectional view showing the perforated plate provided in the pressurized water reactor which concerns on Example 11 of this invention. It is a top view of the guide member of Example 11.

Explanation of symbols

12 Pressurized water reactor 41 Reactor vessel (pressure vessel)
44 Inlet nozzle (coolant inlet nozzle)
45 Outlet nozzle (coolant outlet nozzle)
46 Core tank 48 Lower core plate 53 Core 56 In-core instrumentation guide tube 57 Upper plenum 58 Lower plenum 59 Downcomer section 61, 62, 63 ... 68, 69 Communication holes 71, 81, 82, 83, 91, 101 , 102, 103, 111, 121, 122 Perforated plate (flow resistance changing member)
72, 84, 85, 86, 92, 104, 105, 106, 112, 123, 124 Support cylinder 104a, 105a, 106a, 112a Passage 115 Inner cylinder 125, 126 Plug member (opening ratio adjusting member)
131,132 Guide member (flow resistance changing member)

Claims (13)

  A reactor containment vessel, a pressure vessel housed in the reactor containment vessel, and a coolant supply piping system for supplying a coolant into the pressure vessel, and heat exchange between the nuclear fuel and the coolant In a nuclear reactor that generates steam by generating steam by driving a power generation turbine with the generated steam, a flow resistance that changes the flow resistance of the coolant at the inlet or outlet of the communication hole for supplying the coolant to the nuclear fuel A nuclear reactor characterized by comprising a change member.   A pressure vessel having a coolant inlet nozzle and a coolant outlet nozzle at an upper portion, a reactor core tank disposed in the pressure vessel, a reactor core disposed in the reactor core tank, and a lower portion of the reactor core tank connected to the reactor; A core plate supporting the core, a lower plenum defined by the core plate and the pressure vessel, and defined by a side wall of the pressure vessel and the core tank and communicated with the coolant inlet nozzle and connected to the lower plenum. In a nuclear reactor having a communicating downcomer portion, a large number of communication holes are formed in the core plate to communicate the core and the lower plenum, and flow in the communication hole above or below the core plate. A reactor having a flow resistance changing member for changing a flow resistance of a coolant to be cooled.   The flow resistance changing member is characterized in that the flow resistance of the communication hole formed in the central portion of the core plate is set larger than the flow resistance of the communication hole formed in the outer peripheral portion of the core plate. The nuclear reactor according to claim 1 or 2.   4. The atom according to claim 1, wherein the flow resistance changing member is provided with a porous plate at an inlet portion or an outlet portion of a communication hole formed in a central portion of the core plate. Furnace.   The aperture ratio of the porous plate provided in the communication hole located on the center side of the core plate is set lower than the aperture ratio of the porous plate provided in the communication hole located on the outer peripheral side of the core plate. The nuclear reactor according to claim 4.   The perforated plate is attached to the upper or lower surface of the core plate via a support cylinder, and the height of the perforated plate provided in the communication hole located on the center side of the core plate is equal to the outer periphery of the core plate. The nuclear reactor according to claim 4, wherein the nuclear reactor is set to be lower than a height of the perforated plate provided in the communication hole located on a side.   The nuclear reactor according to claim 4, wherein the perforated plate is attached to an upper surface or a lower surface of the core plate through a support cylinder, and a flow path is formed in the support cylinder.   The height of the porous plate provided in the communication hole located on the center side of the core plate is set lower than the height of the porous plate provided in the communication hole located on the outer peripheral side of the core plate. The nuclear reactor according to claim 7.   The nuclear reactor according to claim 7, wherein the flow path of the support cylinder is formed on a center side of the core plate.   The nuclear reactor according to claim 7, wherein an inner cylinder having a plurality of flow paths is provided inside the support cylinder.   The nuclear reactor according to claim 4, wherein an aperture ratio adjusting member capable of adjusting an aperture ratio of the porous plate is provided.   4. The nuclear reactor according to claim 1, wherein a guide member that introduces a coolant that flows under the core plate into the communication hole is provided as the flow resistance changing member. 5.   The height of the guide member provided in the communication hole located on the center side of the core plate is set lower than the height of the guide member provided in the communication hole located on the outer peripheral side of the core plate. The nuclear reactor according to claim 12, wherein:

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