JP2022060701A - Atomic reactor - Google Patents

Abstract

To provide an atomic reactor capable of maintaining the soundness of a structure by suppressing the generation of spiral convection as a coolant descends a descending flow path.SOLUTION: The atomic reactor includes: a container; a coolant ascending flow path provided inside the container; a coolant descending flow path provided at the center side of the container than the coolant ascending flow path, an upper end of which communicates with an upper end of the coolant ascending flow path; and a convection suppression member provided on the coolant descending flow path for suppressing the generation of convection.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to, for example, a nuclear reactor used as a fast reactor.

A fast reactor is configured by arranging a core, a pump, an intermediate heat exchanger, a furnace wall cooling unit, and the like inside the main container. The furnace wall cooling unit is for suppressing heat transfer from the hot pool to the main container. The furnace wall cooling unit has an outer partition plate and an inner partition plate provided along the inner surface of the main container. As the furnace wall cooling unit, an ascending flow path provided between the main container and the outer partition plate and a descending flow path provided between the outer partition plate and the inner partition plate are provided. Therefore, the coolant rises in the ascending flow path, passes through the outer partition plate, moves to the descending flow path, and descends. At this time, the inner wall surface of the main container is cooled by the coolant.

Examples of the fast reactor having a furnace wall cooling unit include those described in the following patent documents. In Patent Document 1, an outer liner and an inner liner are arranged inside the furnace vessel to provide an outer annulus portion as an upper / descending flow path and an inner annulus portion as a descending flow path, and a partition wall is arranged above the inner annulus portion. It was done. Further, in Patent Document 2, a plurality of walls are arranged inside the reactor vessel to provide a plurality of cooling flow paths as an upper / descending flow path and a descending flow path, and a partition is arranged in the cooling flow path which is a descending flow path. It was done.

Japanese Patent No. 2972162 Japanese Unexamined Patent Publication No. 08-160178

In a fast reactor, the temperature near the free liquid level of the coolant stored in the main container changes significantly, so that a large thermal stress acts on the main container in contact with the liquid level. In order to ensure the structural soundness of the main container, the fast reactor is provided with the above-mentioned furnace wall cooling unit. That is, in the furnace wall cooling unit, the coolant rises in the ascending flow path to cool the main container, and then moves beyond the outer partition plate to the descending flow path and descends. However, in the descending flow path from which the coolant descends, the outer partition plate serves as a non-heated surface, and the inner partition plate serves as a heated surface. Therefore, when the coolant descends from the descending flow path, the coolant is heated by the inner partition plate, which is a heating surface, to a high temperature, and a part of the coolant rises due to buoyancy, and vortex-shaped convection occurs. Then, the outer partition plate, the inner partition plate, and the like are alternately exposed to the low-temperature downward flow and the high-temperature upward flow, and thermal fatigue may threaten the structural soundness.

In the above-mentioned Patent Document 1, by arranging the partition wall on the upper part of the inner annulus portion which becomes the descending flow path, the flow when the coolant moves from the ascending flow path to the descending flow path is stabilized. Further, in Patent Document 2, by arranging a partition in the cooling flow path serving as the descending flow path, it is possible to prevent the generation of a pressure wave when the coolant falls from the ascending flow path to the descending flow path and to prevent the pressure wave from being generated. It prevents propagation. Patent Documents 1 and 2 solve the problem when the coolant moves from the ascending flow path to the descending flow path. Therefore, it is difficult to suppress the vortex-shaped convection that occurs when the coolant descends the descending flow path.

The present disclosure solves the above-mentioned problems, and provides a nuclear reactor that maintains the soundness of a structure by suppressing the generation of spiral convection when the coolant descends the descending flow path. The purpose.

The reactor of the present disclosure for achieving the above object is provided in a container, a coolant ascending flow path provided inside the container, and an upper end portion provided on the center side of the container from the coolant ascending flow path. Is provided with a coolant descending flow path communicating with the upper end of the coolant ascending flow path and a convection generation suppressing member provided in the coolant descending flow path to suppress the generation of convection.

According to the reactor of the present disclosure, the soundness of the structure can be maintained by suppressing the generation of spiral convection when the coolant descends the descending flow path.

FIG. 1 is a schematic view schematically showing the internal structure of the tank-type nuclear reactor of the first embodiment. FIG. 2 is a cross-sectional view showing a furnace wall cooling unit. FIG. 3 is a schematic view showing the flow of the primary coolant in the furnace wall cooling section. FIG. 4 is a cross-sectional view showing a modified example of the furnace wall cooling portion in the tank type reactor of the first embodiment. FIG. 5 is a cross-sectional view showing a furnace wall cooling unit in the tank type reactor of the second embodiment. FIG. 6 is a sectional view taken along line VI-VI of FIG. FIG. 7 is a schematic view showing the flow of the primary coolant in the furnace wall cooling unit. FIG. 8 is a cross-sectional view showing a furnace wall cooling unit in the tank type reactor of the third embodiment.

Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. It should be noted that the present disclosure is not limited to this embodiment, and when there are a plurality of embodiments, the present embodiment also includes a combination of the respective embodiments. Further, the components in the embodiment include those that can be easily assumed by those skilled in the art, those that are substantially the same, that are, those in a so-called equal range.

[First Embodiment]
<Reactor configuration>
FIG. 1 is a schematic view schematically showing the internal structure of the tank-type nuclear reactor of the first embodiment.

In the first embodiment, as shown in FIG. 1, the tank-type nuclear reactor 10 is a fast reactor that generates energy by using a fission chain reaction with fast neutrons. The fast reactor uses liquid metal as a coolant, and here, metallic sodium is used. As the liquid metal, for example, lead, bismuth, an alloy of lead and bismuth, mercury, potassium, NaK (sodium-potassium alloy) and the like can be used in addition to metallic sodium.

The tank reactor 10 has a main container 11. The main container 11 has a cylindrical shape in which the lower portion is closed in a hemispherical shape, and the primary coolant is stored inside. The main container 11 is provided with a roof deck 12 at the top. In the main container 11, a strong back 13, a diamond grid 14, and a core tank 15 having a core are arranged inside. The strong back 13 is provided in the lower part of the main container 11, the diamond grid 14 is arranged in the upper part of the strong back 13, and the core tank 15 is arranged in the upper part of the diamond grid 14. In the core tank 15, a plurality of fuel assemblies 16 constituting the core are arranged.

In the main container 11, a core superstructure 18, a pump 19, and an intermediate heat exchanger 20 are arranged inside. The core superstructure 18 is arranged at the radial center of the main container 11, and the upper part is supported by the roof deck 12. The pump 19 and the intermediate heat exchanger 20 are arranged on the outer peripheral side in the radial direction of the main container 11, and the upper portion is supported by the roof deck 12. The pump 19 is provided with a suction port and a discharge port (not shown) at the lower part, and the discharge port is connected to the diamond grid 14 by the in-core pipe 21.

The intermediate heat exchanger 20 is connected to a supply pipe 22 to which a secondary coolant is supplied from a steam generator (not shown), and is a discharge pipe that discharges the secondary coolant whose temperature has risen due to heat exchange to the steam generator. 23 are connected. The intermediate heat exchanger 20 is provided with an inflow port 24 at the upper part and an outflow port 25 at the lower part. In the intermediate heat exchanger 20, the primary coolant of the main container 11 flows in from the inflow port 24 and flows out from the outflow port 25. At this time, the intermediate heat exchanger 20 exchanges heat between the high-temperature primary coolant and the low-temperature secondary coolant.

The main container 11 is provided with a furnace wall cooling unit 30 on the outer peripheral portion. The furnace wall cooling unit 30 suppresses heat transfer from the hot pool 41 to the main container 11.

The furnace wall cooling unit 30 has an inner partition plate 32, an outer partition plate 33, and a furnace wall cooling pipe 34.

The main container 11 is divided into a hot pool 41 and a cold pool 42 by an inner container 31. The inner container 31 has a substantially cylindrical shape and has a vertical partition plate 31a and a horizontal partition plate 31b arranged from above to below in the vertical direction. The outer diameter of the vertical partition plate 31a is slightly smaller than the inner diameter of the main container 11. The horizontal partition plate 31b connects the vertical partition plate 31a and the core tank 15, and is slightly inclined downward from the vertical partition plate 31a toward the core tank 15. The horizontal partition plate 31b may be horizontal without being inclined. The lower portion of the vertical partition plate 31a is integrally connected to the outer diameter portion of the horizontal partition plate 31b, and the inner diameter portion of the horizontal partition plate 31b is connected to the upper portion of the core tank 15. The hot pool 41 is a region inside the vertical partition plate 31a and above the horizontal partition plate 31b. The cold pool 42 is a region outside the vertical partition plate 31a and below the horizontal partition plate 31b.

The inner partition plate 32 has a cylindrical shape. The inner diameter of the inner partition plate 32 is larger than the outer diameter of the vertical partition plate 31a of the inner container 31. The inner partition plate 32 is arranged outside the vertical partition plate 31a of the inner container 31. The vertical partition plate 31a and the inner partition plate 32 of the inner container 31 have substantially the same height in the upper part in the vertical direction, and the vertical partition plate 31a and the inner partition plate 32 in the inner container 31 are in the lower part in the vertical direction. The height is almost the same. The outer partition plate 33 has a cylindrical shape. The inner diameter of the outer partition plate 33 is larger than the outer diameter of the inner partition plate 32. The outer partition plate 33 is arranged outside the inner partition plate 32. The height of the outer partition plate 33 in the upper part in the vertical direction is lower than that of the inner partition plate 32, and the height in the lower part in the vertical direction is the same as that of the inner partition plate 32.

The main container 11 is provided with a coolant rising flow path 43 between the inner surface of the main container 11 and the outer surface of the outer partition plate 33. The main container 11 is provided with a coolant descending flow path 44 between the inner surface of the outer partition plate 33 and the outer surface of the inner partition plate 32. Further, the main container 11 is provided with a stagnant portion 45 between the inner surface of the inner partition plate 32 and the outer surface of the vertical partition plate 31a of the inner container 31. The coolant ascending flow path 43, the coolant descending flow path 44, and the stagnant portion 45 are ring-shaped space portions.

The upper part of the coolant ascending flow path 43 is opened, and the lower part is closed by the closing plate 35. The closing plate 35 is fixed to the lower part of the main container 11 and the outer partition plate 33. One end of the furnace wall cooling pipe 34 is connected to the closing plate 35, and the other end is connected to the strong back 13. The coolant ascending flow path 43 communicates with the strong back 13 by the furnace wall cooling pipe 34. The upper and lower portions of the coolant descending flow path 44 are opened. The perforated plate 36 is fixed to the lower part of the outer partition plate 33 and the inner partition plate 32. The coolant ascending flow path 43 and the coolant descending flow path 44 communicate with each other upward, and the coolant descending flow path 44 communicates with the cold pool 42 via the perforated plate 36. The primary coolant is stored in the main container 11. In the primary cooling material, the liquid level S is maintained below the upper end portion of the inner container 31 and the inner partition plate 32 and above the upper end portion of the outer partition plate 33. That is, the furnace wall cooling unit 30 is a diving weir system in which the upper ends of the cooling material ascending flow path 43 and the cooling material descending flow path 44 communicate with each other below the liquid level S of the primary cooling material.

<Reactor operation>
When the pump 19 is operated, the low-temperature primary coolant stored in the cold pool 42 is sucked from the suction port at the lower part of the pump 19 and is supplied from the discharge port to the diamond grid 14 through the in-core pipe 21. The primary coolant supplied to the diamond grid 14 is heated in the core tank 15 and rises to a high temperature. The high temperature primary coolant flows into the intermediate heat exchanger 20 from the inflow port 24. At this time, the intermediate heat exchanger 20 exchanges heat between the high-temperature primary coolant and the secondary coolant supplied from the supply pipe 22. The secondary coolant that has become hot due to heat exchange is sent from the discharge pipe 23 to the steam generator. On the other hand, the primary coolant whose temperature has become low due to heat exchange flows out from the outlet 25 to the cold pool 42.

A part of the primary coolant of the diamond grid 14 flows to the strong back 13, and is supplied to the coolant ascending flow path 43 by the furnace wall cooling pipe 34. The primary coolant rises in the coolant ascending flow path 43, flows from the upper end portion to the coolant descending flow path 44, descends in the coolant descending flow path 44, and flows out to the cold pool 42. At this time, the primary coolant flows through the coolant ascending flow path 43 and the coolant descending flow path 44, so that the inner wall surface of the main container 11 is cooled.

<Convection generation suppression member configuration>
FIG. 2 is a cross-sectional view showing a furnace wall cooling unit.

As shown in FIG. 2, the tank-type reactor 10 of the first embodiment has a convection generation suppressing member 50. The convection generation suppressing member 50 is provided in the coolant descending flow path 44 of the furnace wall cooling unit 30. The convection generation suppressing member 50 suppresses the generation of convection in the primary coolant descending the coolant descending flow path 44.

The convection generation suppressing member 50 is provided at the lower part of the coolant descending flow path 44. Here, the lower part of the coolant descending flow path 44 is a region below the intermediate position in the longitudinal direction (vertical direction) of the coolant descending flow path 44. That is, when the total length L of the coolant descending flow path 44 and the intermediate position M which is 1/2 of the total length L are set, the coolant descending flow path 44 is located above the intermediate position M and above the upper region A1 and from the intermediate position M. It is partitioned into the lower region A2 on the lower side. The convection generation suppressing member 50 is arranged only in the lower region A2 and not in the upper region A1.

The convection generation suppressing member 50 has a resistance plate 51 that reduces the passage area of the coolant descending flow path 44 to provide the gap passage 44a. A plurality of resistance plates 51 (three in the present embodiment) are arranged in the lower region A2 of the coolant descending flow path 44 at predetermined intervals in the longitudinal direction. The number of resistance plates 51 is not limited to this embodiment, and is appropriately set according to the total length of the coolant descending flow path 44.

The resistance plate 51 has a disk shape of a ring provided with a circular hole in the center. The outer diameter of the resistance plate 51 is the same as the inner diameter of the outer partition plate 33. Further, the inner diameter of the resistance plate 51 is larger than the outer diameter of the inner partition plate 32. In the resistance plate 51, the outer peripheral portion 51a is fixed to the inner surface of the outer partition plate 33, and the inner peripheral portion 51b faces the outer surface of the inner partition plate 32 with a predetermined gap. That is, a gap passage 44a is provided between the inner peripheral portion 51b of the resistance plate 51 and the outer surface of the inner partition plate 32. The gap passage 44a is continuous along the circumferential direction of the outer surface of the inner partition plate 32.

<Action of convection suppression member>
FIG. 3 is a schematic view showing the flow of the primary coolant in the furnace wall cooling section.

As shown in FIGS. 2 and 3, the primary coolant rises in the coolant ascending flow path 43, flows from the upper end portion to the coolant descending flow path 44, and descends in the coolant descending flow path 44. In the coolant descending flow path 44, the inner surface of the outer partition plate 33 is a non-heated surface, and the outer surface of the inner partition plate 32 is a heated surface. At this time, the primary coolant descending the coolant descending flow path 44 is heated by the inner partition plate 32, which is a heating surface, to a high temperature, and a part of the primary coolant rises due to buoyancy, and vortex-shaped convection is likely to occur.

Therefore, in the present embodiment, a plurality of resistance plates 51 as convection generation suppressing members 50 are arranged in the coolant descending flow path 44. Therefore, the high-temperature primary coolant C1 descending along the inner partition plate 32 flows into the gap passage 44a. Further, the low-temperature primary coolant C2 descending along the outer partition plate 33 flows to the gap passage 44a side by the resistance plate 51. Then, the high-temperature primary coolant C1 and the low-temperature primary coolant C2 are mixed in the vicinity of the gap passage 44a to form a downward convection of the primary coolant C3, and the temperature of the primary coolant C1 is higher than that in the case where they are not mixed. Since it is suppressed, the temperature difference between the low temperature primary coolant and the high temperature primary coolant becomes small, and convection due to buoyancy can be suppressed. Further, the flow velocity of the downward flow of the primary coolant C3 increases when it passes through the gap passage 44a. Then, the ascending current of the high-temperature primary coolant C4 that rises due to the generation of vortex-shaped convection is suppressed by the descending flow of the primary coolant C3 that descends at high speed. Therefore, the inner partition plate 32, the outer partition plate 33, and the like are not alternately exposed to the lowering low-temperature primary coolant C2 and the rising high-temperature primary coolant C4, and the structural soundness is threatened by thermal fatigue. There is no such thing.

<Modification example>
The convection generation suppressing member of the present invention is not limited to the above-mentioned configuration. FIG. 4 is a cross-sectional view showing a modified example of the furnace wall cooling portion in the tank type reactor of the first embodiment.

In the modified example of the first embodiment, as shown in FIG. 4, the convection generation suppressing member 50A is provided in the coolant descending flow path 44 of the furnace wall cooling unit 30. The convection generation suppressing member 50A suppresses the generation of convection in the primary coolant descending the coolant descending flow path 44.

The convection generation suppressing member 50A is provided over the entire length of the coolant descending flow path 44. The convection generation suppressing member 50A has a resistance plate 51 that reduces the passage area of the coolant descending flow path 44 to provide the gap passage 44a. A plurality of resistance plates 51 (six in the present embodiment) are arranged at predetermined intervals in the longitudinal direction over the entire length of the coolant descending flow path 44. The number of resistance plates 51 is not limited to this embodiment, and is appropriately set according to the total length of the coolant descending flow path 44.

Even in the convection generation suppressing member 50A, similarly to the convection generation suppressing member 50, the high temperature primary coolant descending along the inner partition plate 32 and the low temperature primary coolant descending along the outer partition plate 33. However, the mixture is mixed in the gap passage 44a, and the flow velocity increases and descends. Therefore, it is possible to suppress the high-temperature primary coolant that rises due to the generation of vortex-shaped convection due to the primary coolant that descends at high speed.

[Second Embodiment]
FIG. 5 is a cross-sectional view showing a furnace wall cooling section in the tank-type reactor of the second embodiment, FIG. 6 is a sectional view taken along the line VI-VI of FIG. 5, and FIG. 7 is a flow of the primary coolant in the furnace wall cooling section. It is a schematic diagram which shows. The basic configuration of the second embodiment is the same as that of the first embodiment described above, and the members having the same functions as those of the first embodiment described above will be described with reference to FIG. Reference numerals are given and detailed description thereof will be omitted.

In the second embodiment, as shown in FIGS. 5 and 6, the convection generation suppressing member 50B is provided in the coolant descending flow path 44 of the furnace wall cooling unit 30. The convection generation suppressing member 50B suppresses the generation of convection in the primary coolant descending the coolant descending flow path 44. The convection generation suppressing member 50B is provided at the lower part of the coolant descending flow path 44.

The convection generation suppressing member 50B has a resistance plate 52 that reduces the passage area of the coolant descending flow path 44 to provide the gap passage 44a. A plurality of resistance plates 52 (three in the present embodiment) are arranged below the coolant descending flow path 44 at predetermined intervals in the longitudinal direction.

The resistance plate 52 has a ring-shaped disk shape with a circular hole in the center. In the resistance plate 52, the outer peripheral portion 52a is fixed to the inner surface of the outer partition plate 33, and the inner peripheral portion 52b faces the outer surface of the inner partition plate 32 with a predetermined gap. That is, a gap passage 44a is provided between the inner peripheral portion 52b of the resistance plate 52 and the outer surface of the inner partition plate 32. The gap passage 44a is continuous along the circumferential direction of the outer surface of the inner partition plate 32.

The resistance plate 52 is provided with a plurality of through holes 53. The through hole 53 is circular, but may have an elliptical shape, a polygonal shape, a slit shape, or the like. Further, although the plurality of through holes 53 are arranged in a houndstooth pattern, they may be in a lattice pattern or a random pattern. Further, although the plurality of through holes 53 are provided in the entire area of the resistance plate 52, they are provided only on the outer peripheral portion 52a side, only on the inner peripheral portion 52b side, or only between the outer peripheral portion 52a and the inner peripheral portion 52b. It may be provided in. The opening area of one of the through holes 53 is preferably smaller than the opening area of the gap passage 44a. Further, the total opening area of the plurality of through holes 53, which is the total opening area of the through holes 53, may be smaller than the opening area of the gap passage 44a.

FIG. 7 is a schematic view showing the flow of the primary coolant in the furnace wall cooling section.

As shown in FIGS. 5 and 7, the primary coolant rises in the coolant ascending flow path 43, flows from the upper end portion to the coolant descending flow path 44, and descends in the coolant descending flow path 44. At this time, the high-temperature primary coolant C1 descending along the inner partition plate 32 flows into the gap passage 44a. Further, the low-temperature primary coolant C2 descending along the outer partition plate 33 flows to the gap passage 44a side by the resistance plate 52. Then, the high-temperature primary coolant C1 and the low-temperature primary coolant C2 are mixed in the gap passage 44a to form a downward convection of the primary coolant C3, and the temperature of the primary coolant C1 is suppressed as compared with the case where they are not mixed. Therefore, the temperature difference between the low-temperature primary coolant and the high-temperature primary coolant becomes small, and convection due to buoyancy can be suppressed. Further, the flow velocity of the downward flow of the primary coolant C3 increases when it passes through the gap passage 44a. Then, the ascending current of the high-temperature primary coolant C4 that rises due to the generation of vortex-shaped convection is suppressed by the descending flow of the primary coolant C3 that descends at high speed. Therefore, the inner partition plate 32, the outer partition plate 33, and the like are not alternately exposed to the lowering low-temperature primary coolant C2 and the rising high-temperature primary coolant C4, and the structural soundness is threatened by thermal fatigue. There is no such thing.

Further, since the primary coolant C3 descends through the gap passage 44a, the primary coolant tends to stagnate in the region on the lower side of the outer peripheral portion 52a of the resistance plate 52. Therefore, in the present embodiment, the resistance plate 52 is provided with a plurality of through holes 53. Therefore, a part of the low-temperature primary coolant C2 descending along the outer partition plate 33 becomes a downward flow of the primary coolant C5 passing through the plurality of through holes 53. Then, in the region on the lower side of the outer peripheral portion 52a of the resistance plate 52, the flow of the primary coolant is generated by the downward flow of the primary coolant C5 that has passed through the plurality of through holes 53, and the stagnation of the primary coolant is eliminated. ..

[Third Embodiment]
FIG. 8 is a cross-sectional view showing a furnace wall cooling unit in the tank type reactor of the third embodiment. The basic configuration of the third embodiment is the same as that of the first embodiment described above, and will be described with reference to FIG. 1. The members having the same functions as those of the first embodiment described above are the same. Reference numerals are given and detailed description thereof will be omitted.

In the third embodiment, as shown in FIG. 8, the convection generation suppressing member 50C is provided in the coolant descending flow path 44 of the furnace wall cooling unit 30. The convection generation suppressing member 50C suppresses the generation of convection in the primary coolant descending the coolant descending flow path 44. The convection generation suppressing member 50C is provided at the lower part of the coolant descending flow path 44.

The convection generation suppressing member 50C has a resistance plate 54 that reduces the passage area of the coolant descending flow path 44 to provide the gap passage 44a. A plurality of resistance plates 54 (three in the present embodiment) are arranged below the coolant descending flow path 44 at predetermined intervals in the longitudinal direction. The resistance plate 54 has a disk shape with a circular hole in the center. The resistance plate 54 is fixed to the inner surface of the outer partition plate 33, and a gap passage 44a is provided on the inner partition plate 32 side. The gap passage 44a is continuous along the circumferential direction of the outer surface of the inner partition plate 32. The resistance plate 54 is provided with a plurality of through holes 55.

The resistance plate 54 is arranged so that one end in the radial direction of the main container 11 is inclined toward the downstream side in the flow direction of the coolant descending flow path 44. That is, the outer peripheral portion of the resistance plate 54 is fixed to the inner surface of the outer partition plate 33, and the inner peripheral portion side is extended downward in the vertical direction toward the inner partition plate 32 side by a predetermined inclination angle θ. .. The resistance plate 54 is inclined by an inclination angle θ with respect to the horizontal direction.

The resistance plate 54 was arranged so that one end in the radial direction of the main container 11 was inclined toward the downstream side in the flow direction of the coolant descending flow path 44, but the resistance plate 54 was arranged in the radial direction of the main container 11. One end of the coolant may be inclined toward the upstream side in the flow direction of the coolant descending flow path 44. That is, the resistance plate 54 may be extended so that the inner peripheral portion side is inclined upward by the inclination angle θ toward the inner partition plate 32 side in the vertical direction.

The primary coolant rises in the coolant ascending flow path 43, flows from the upper end portion to the coolant descending flow path 44, and descends in the coolant descending flow path 44. At this time, the high-temperature primary coolant C1 descending along the inner partition plate 32 flows into the gap passage 44a. Further, the low-temperature primary coolant C2 descending along the outer partition plate 33 flows to the gap passage 44a side by the resistance plate 51. At this time, since the resistance plate 54 is inclined downward on the gap passage 44a side, the low-temperature primary coolant C2 easily flows into the gap passage 44a. Then, the high-temperature primary coolant C1 and the low-temperature primary coolant C2 are mixed in the gap passage 44a to form a downward convection of the primary coolant C3, and the temperature of the primary coolant C1 is suppressed as compared with the case where they are not mixed. Therefore, the temperature difference between the low-temperature primary coolant and the high-temperature primary coolant becomes small, and convection due to buoyancy can be suppressed. Further, the flow velocity of the downward flow of the primary coolant C3 increases when it passes through the gap passage 44a. Then, the ascending current of the high-temperature primary coolant C4 that rises due to the generation of vortex-shaped convection is suppressed by the descending flow of the primary coolant C3 that descends at high speed. Therefore, the inner partition plate 32, the outer partition plate 33, and the like are not alternately exposed to the lowering low-temperature primary coolant C2 and the rising high-temperature primary coolant C4, and the structural soundness is threatened by thermal fatigue. There is no such thing.

Since the resistance plate 54 is inclined, the primary coolant tends to stagnate in the lower region of the outer peripheral portion of the resistance plate 54. Therefore, in the present embodiment, the resistance plate 54 is provided with a plurality of through holes. Therefore, since a part of the primary coolant descends through the plurality of through holes, the stagnation in the lower region of the outer peripheral portion of the resistance plate 54 is eliminated.

[Action and effect of this embodiment]
The reactor according to the first aspect has a main container 11, a coolant rising flow path 43 provided inside the main container 11, and an upper end portion provided on the center side of the main container 11 from the coolant rising flow path 43. The coolant descending flow path 44 communicating with the upper end of the coolant ascending flow path 43 and the convection generation suppressing members 50, 50A, 50B, 50C provided in the coolant descending flow path 44 to suppress the generation of convection. Be prepared.

In the reactor according to the first aspect, convection generation suppressing members 50, 50A, 50B, 50C for suppressing the generation of convection are provided in the coolant descending flow path 44. The primary coolant rises in the coolant ascending flow path 43, flows from the upper end portion to the coolant descending flow path 44, and descends in the coolant descending flow path 44. At this time, the primary coolant descending the coolant descending flow path 44 is heated by the inner partition plate 32, which is a heating surface, to a high temperature, and a part of the primary coolant rises due to buoyancy, and vortex-shaped convection is likely to occur. However, in the primary coolant descending the coolant descending flow path 44, the generation of convection is suppressed by the convection generation suppressing members 50, 50A, 50B, 50C. Therefore, the soundness of structures such as the main container 11, the inner partition plate 32, and the outer partition plate 33 can be maintained.

Further, since the convection generation suppressing members 50, 50A, 50B, and 50C are provided in the coolant descending flow path 44, the inner partition plate 32 and the outer partition plate 33 forming the coolant descending flow path 44 approach each other. When the convection generation suppressing members 50, 50A, 50B, and 50C function as support members when attempting to thermally deform in the direction, large deformation of the inner partition plate 32 and the outer partition plate 33 can be suppressed.

In the reactor according to the second aspect, the convection generation suppressing members 50, 50A, 50B, 50C are provided at the lower part in the coolant descending flow path 44. As a result, when the primary coolant descends the coolant descending flow path 44, vortex-shaped convection is generated at the lower part of the coolant descending flow path 44. Therefore, by arranging the convection generation suppressing members 50, 50A, 50B, 50C at the lower part of the coolant descending flow path 44, the generation of vortex-shaped convection magic can be effectively suppressed.

In the reactor according to the third aspect, the convection generation suppressing members 50, 50A, 50B, 50C have resistance plates 51, 52, 54 forming a gap passage 44a in which the passage area of the coolant descending flow path 44 is reduced. .. As a result, the primary coolant descending the coolant descending flow path 44 is accelerated when passing through the gap passage 44a, so that the rise of the primary coolant due to the generation of convection can be appropriately suppressed.

In the reactor according to the fourth aspect, a plurality of resistance plates 51, 52, 54 are arranged at predetermined intervals in the longitudinal direction of the coolant descending flow path 44. As a result, the generation of convection can be appropriately suppressed by the resistance plates 51, 52, 54 in the predetermined section of the coolant descending flow path 44.

In the reactor according to the fifth aspect, the coolant ascending flow path 43 is provided between the main container 11 and the outer partition plate 33 arranged inside the main container 11, and the coolant descending flow path 44 is provided. The resistance plates 51, 52, 54 are provided between the outer partition plate 33 and the inner partition plate 32 arranged inside the outer partition plate 33, and one end of the resistance plates 51, 52, 54 in the radial direction of the main container 11 is the outer partition plate 33. It is fixed to either one of the inner partition plates 32, and a gap passage 44a is provided between the other end of the main container 11 in the radial direction and between the outer partition plate 33 and any other of the inner partition plates 32. As a result, the high-temperature primary coolant C1 descending along the inner partition plate 32 and the low-temperature primary coolant C2 descending along the outer partition plate 33 merge in the vicinity of the gap passage 44a on the heating surface side. , Accelerates when the gap passage 44a is added. Therefore, it is possible to effectively suppress the generation of vortex-shaped convection that tends to occur on the heating surface side.

In the nuclear reactor according to the sixth aspect, the resistance plate 52 is provided with a through hole 53. As a result, the primary coolant that descends the coolant descending flow path 44 flows toward the gap passage 44a, and a part of the primary coolant descends through the plurality of through holes 53, which is below the outer peripheral portion 52a of the resistance plate 52. A flow of primary coolant is generated in the area on the side, and the stagnation of the primary coolant can be eliminated.

In the reactor according to the seventh aspect, the opening area of the through hole 53 is smaller than the opening area of the gap passage 44a. As a result, the generation of convection can be effectively suppressed, and the stagnation of the primary coolant can be eliminated.

In the reactor according to the eighth aspect, the resistance plate 54 is arranged so that one end in the radial direction of the main container 11 is inclined toward the upstream side or the downstream side in the flow direction of the coolant descending flow path 44. As a result, the primary coolant can be smoothly flowed in the coolant descending flow path 44.

In the reactor according to the ninth aspect, the coolant ascending flow path 43 and the coolant descending flow path 44 communicate with each other at the upper end thereof below the liquid level S of the primary coolant. As a result, the generation of convection can be appropriately suppressed by the resistance plates 51, 52, 54.

In the above-described embodiment, the resistance plates 51, 52, and 54 are fixed to the outer partition plate 33, and the gap passage 44a is provided between the resistance plates 51, 52, and 54 and the inner partition plate 32, but the configuration is not limited to this. For example, the resistance plates 51, 52, 54 may be fixed to the inner partition plate 32, and a gap passage 44a may be provided between the resistance plates 51, 52, and 54 and the outer partition plate 33.

Further, in the above-described embodiment, the resistance plates 51, 52, 54 are continuous in the circumferential direction of the inner partition plate 32 and the outer partition plate 33, but are intermittent in the circumferential direction of the inner partition plate 32 and the outer partition plate 33. It may be provided as a target.

Further, in the above-described embodiment, the furnace wall cooling unit 30 is a diving weir system in which the upper ends of the cooling material ascending flow path 43 and the cooling material descending flow path 44 communicate with each other below the liquid level S of the primary cooling material. However, there may be an overflow method in which the upper ends of the cooling material ascending flow path 43 and the cooling material descending flow path 44 communicate with each other above the liquid level S of the primary cooling material.

Further, in the above-described embodiment, the convection generation suppressing member of the present invention is applied to the furnace wall cooling unit 30 of the tank type nuclear reactor 10, but it can also be applied to a general nuclear reactor. That is, the application location is not limited as long as it is a descending flow path having a non-heated surface and a heated surface.

10 Tank type nuclear reactor (reactor)
11 Main container 12 Roof deck 13 Strong back 14 Diamond grid 15 Core tank 16 Fuel assembly 18 Core superstructure 19 Pump 20 Intermediate heat exchanger 21 In-core piping 22 Supply piping 23 Discharge piping 24 Inflow port 25 Outlet 30 Reactor wall cooling Part 31 Inner container 31a Vertical partition plate 31b Horizontal partition plate 32 Inner partition plate 33 Outer partition plate 34 Reactor wall cooling piping 35 Blocking plate 36 Perforated plate 41 Hot pool 42 Cold pool 43 Coolant ascending flow path 44 Coolant descending flow path 44a Gap passage 45 Stagnanto part 50, 50A, 50B, 50C Convection generation suppression member 51, 52, 54 Resistance plate 53 Through hole A1 Upper area A2 Lower area C1, C2, C3, C4, C5 Primary cooling material L Overall length M Intermediate position S liquid level θ tilt angle

Claims (9)

With the container
The coolant ascending flow path provided inside the container and
A coolant descending flow path provided on the center side of the container from the coolant rising flow path and having an upper end communicating with the upper end portion of the coolant rising flow path.
A convection generation suppressing member provided in the coolant descending flow path and suppressing the generation of convection,
Reactor equipped with. The convection generation suppressing member is provided at the lower part of the coolant descending flow path.
The nuclear reactor according to claim 1. The convection generation suppressing member has a resistance plate that forms a gap passage in which the passage area of the coolant descending flow path is reduced.
The nuclear reactor according to claim 1 or 2. A plurality of the resistance plates are arranged at predetermined intervals in the longitudinal direction of the coolant descending flow path.
The nuclear reactor according to claim 3. The coolant ascending flow path is provided between the container and the outer partition plate arranged inside the container, and the coolant descending flow path is arranged inside the outer partition plate and the outer partition plate. The resistance plate is provided between the inner partition plate and the inner partition plate, and one end of the resistance plate in the radial direction of the container is fixed to either the outer partition plate or the inner partition plate in the radial direction of the container. The gap passage is provided between the portion, the outer partition plate, and any one of the inner partition plates.
The nuclear reactor according to claim 3 or 4. The resistance plate is provided with a through hole.
The nuclear reactor according to any one of claims 3 to 5. The opening area of the through hole is smaller than the opening area of the gap passage.
The nuclear reactor according to claim 6. The resistance plate is arranged so that one end in the radial direction of the container is inclined toward the upstream side or the downstream side in the flow direction of the coolant descending flow path.
The nuclear reactor according to any one of claims 3 to 7. The upper end of the cooling material ascending flow path and the cooling material descending flow path communicate with each other below the cooling material liquid level.
The nuclear reactor according to any one of claims 1 to 8.

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