JP7200153B2 - Molten fuel outflow tube of fast reactor and fast reactor - Google Patents

Description

The present invention relates to a molten fuel outflow tube for a fast reactor and a fast reactor.

Fuel assemblies and control rods are arranged in the core of a fast reactor, and the control rods are housed in control rod guide tubes. Core damage may occur in fast reactors. From the viewpoint of preventing re-criticality of the molten fuel in the fuel assemblies when the core is damaged, it has been proposed to let the molten fuel flow out to the debris core catcher via the control rod guide tube (for example, see below (see Patent Document 1).

JP 2016-125837 A

In Patent Literature 1, the melted fuel that melts and enters the peripheral wall of the control rod guide tube melts the dashpot in the control rod guide tube, thereby forming an outflow passage for the melted fuel to flow out. However, since the fusion point of the dashpot is far from the melting point of the peripheral wall, the temperature of the molten fuel drops as the heat is absorbed by contact with other members and coolant before the molten fuel reaches the dashpot. Resulting in. If the temperature of the molten fuel drops, the dashpot may not be properly fused by the molten fuel and the molten fuel may not flow out.

Accordingly, the present invention has been made in view of these points, and an object of the present invention is to properly flow out molten fuel from a fast reactor.

According to a first aspect of the present invention, there is provided a molten fuel outflow pipe for a fast reactor provided in a core of a fast reactor, wherein an inner region is filled with a coolant, and a cylindrical portion adjacent to a heat generating region of the core. and a lower opening formed at the lower end side of the cylindrical portion in the axial direction, and a flow path portion provided in the inner region from the lower end side to the upper end side and through which the inflow coolant flows, The cylindrical portion can be melted by the heat of the molten fuel in the heat generating region, and the inner region and the lower opening serve as an outflow passage for the molten fuel that has flowed into the cylindrical portion due to the melted fuel in the cylindrical portion. To provide a molten fuel outflow tube for a fast reactor.

Further, the cylindrical portion may accommodate control rods of the fast reactor, and the flow path portion may be positioned around the control rods.

Further, the flow path part may be provided in plurality at predetermined intervals in the circumferential direction in the inner region.

Further, the flow path portion may be positioned apart from the inner wall surface of the cylindrical portion.

Further, a partition wall is provided on the upper end side in the cylindrical portion and divides the internal region into an upper region and a lower region, and the partition wall is a first communication port that communicates the flow path portion and the upper region. , and a second communication port that communicates the upper region and the lower region.

A second aspect of the present invention is a fast reactor in which a plurality of molten fuel outflow pipes are arranged dispersedly in a core, wherein an inner region of the molten fuel outflow pipe is filled with a coolant, a tubular portion adjacent to the heat generating region of the core; a lower opening formed at the lower end side of the tubular portion in the axial direction; and a channel portion through which the gas flows, wherein the upper end of the cylindrical portion in the axial direction is positioned above the heat generating region, and the lower end of the cylindrical portion in the axial direction is positioned below the heat generating region. The cylindrical portion can be melted by the heat of the molten fuel in the heat generating region, and the inner region and the lower opening are configured to flow out the molten fuel that has flowed into the cylindrical portion due to the melting of the cylindrical portion. Provide a fast reactor that will become a road.

ADVANTAGE OF THE INVENTION According to this invention, it is effective in the ability to flow out molten fuel of a fast reactor appropriately.

1 is a schematic diagram for explaining an example of the configuration of a fast reactor 1 according to one embodiment; FIG. FIG. 3 is a schematic diagram for explaining an example of an arrangement state of core component groups; 4 is a schematic diagram for explaining the configuration of a guide tube 60; FIG. 6 is a schematic diagram for explaining the cross-sectional configuration of the guide tube 60. FIG. FIG. 4 is a schematic diagram for explaining an outflow route of molten fuel; FIG. 11 is a schematic diagram for explaining a modification of the flow path portion 65; 4 is a schematic diagram for explaining the configuration of an outflow pipe 70. FIG. FIG. 3 is a schematic diagram for explaining a cross-sectional configuration of an outflow pipe 70; FIG. 4 is a schematic diagram for explaining an outflow route of molten fuel; 7A and 7B are schematic diagrams for explaining a modification of the flow path portion 75; FIG.

<First Embodiment>
(Composition of fast reactor)
A configuration of a fast reactor according to one embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG.

FIG. 1 is a schematic diagram for explaining an example of the configuration of a fast reactor 1 according to one embodiment. The fast reactor 1 uses, for example, uranium, plutonium, or the like as fuel to sustain and control a nuclear fission chain reaction, thereby extracting energy. The fast reactor 1 is a tank-type fast reactor in which an intermediate heat exchanger and a pump are provided in the main vessel. However, the fast reactor 1 is not limited to this. For example, the fast reactor 1 may be a loop-type fast reactor in which an intermediate heat exchanger and a pump are provided outside the main vessel.

As shown in FIG. 1, the fast reactor 1 includes a main vessel 3, a core 5, a core barrel 7, a core superstructure 9, a diamond grid 11, a pump 13, a pipe 15, a partition plate 17, It has an intermediate heat exchanger 19 and a core catcher 21 . In FIG. 1, arrows indicate the flow of the coolant. FIG. 1 also shows one guide tube 60, which will be described later.

The main container 3 is a thin-walled, large-diameter container. The diameter of the main container 3 is, for example, about 15m to 20m.
A core 5 is arranged in the central portion of the main vessel 3 . The core 5 has an exothermic region 5a in which a nuclear fission chain reaction can occur.

The core barrel 7 is a barrel containing the core 5 . The core barrel 7 is provided above the diamond grid 11 . Inside the core barrel 7, core component groups (fuel assemblies, control rods, etc.) are arranged.
A core superstructure 9 is positioned directly above the core components. The core superstructure 9 is provided with various measuring devices such as a control rod drive mechanism, a thermometer, and a fuel failure position detector.

Diagrid 11 functions as an inlet for introducing coolant into core 5 . The coolant flows into the core 5 and cools the core 5 during normal operation of the fast reactor 1 . The coolant is liquid metal sodium as an example, but is not limited to this. Diagrid 11 is provided with a large number of cylindrical connection pipes for inserting the lower ends of core components.

The pump 13 generates power for circulating the coolant within the main container 3 . A pump 13 draws in the coolant and directs it to the core 5 . Although one pump 13 is shown in FIG. 1, a plurality of pumps 13 are provided in the main container 3 along the circumferential direction at predetermined intervals.

A pipe 15 is a pipe connecting the diagrid 11 and the pump 13 . The coolant sucked by the pump 13 flows through the pipe 15 to the diagrid 11 .

The partition plate 17 is a wall that divides the inside of the main container 3 into an upper plenum and a lower plenum. The area above the partition plate 17 is the upper plenum, and the area below the partition plate 17 is the lower plenum.

The intermediate heat exchanger 19 exchanges heat with the coolant to reduce the temperature of the coolant. The intermediate heat exchanger 19 is provided along the vertical direction within the main vessel 3 . Intermediate heat exchanger 19 has an inlet 19a located in the upper plenum and an outlet 19b located in the lower plenum. The inflow port 19a is an opening through which the high-temperature coolant of the upper plenum that has passed through the core 5 flows. The high-temperature coolant that has flowed in from the inflow port 19 a undergoes heat exchange within the intermediate heat exchanger 19 . The outflow port 19b is an opening through which the coolant whose temperature has been lowered by heat exchange flows out to the lower plenum. Although one intermediate heat exchanger 19 is shown in FIG. 1, a plurality of intermediate heat exchangers 19 are provided in the main vessel 3 along the circumferential direction at predetermined intervals.

A core damage accident may occur in the fast reactor 1 . Therefore, in the first embodiment, when a core damage accident occurs, the molten fuel in the core 5 is allowed to flow out to the core catcher 21 through a molten fuel outflow pipe (details will be described later).

A core catcher 21 is arranged at the bottom of the main container 3 . That is, the core catcher 21 is located in the lower plenum. The core catcher 21 receives at least one of molten fuel in the core 5, a solidified substance of the molten fuel, and a mixture of the molten fuel and the solidified substance (simply referred to as molten fuel for convenience of explanation). Further, the core catcher 21 has a function as a cooling portion for cooling the received molten fuel. This prevents the melted fuel from melting the main container 3 and leaking to the outside.

(Arrangement of core component groups)
The arrangement state of the core component groups of the core 5 will be described with reference to FIG.
FIG. 2 is a schematic diagram for explaining an example of the arrangement of core component groups. As shown in FIG. 2, the core 5 is provided with fuel assemblies 50, control rod assemblies 55, and outflow pipes 70 as core component groups. In FIG. 2, for convenience of explanation, the fuel assemblies 50 are indicated by white hexagons, the control rod assemblies 55 are indicated by black hexagons, and the outflow tubes 70 are indicated by hatched hexagons. there is

In the core 5, a plurality of fuel assemblies 50, control rod assemblies 55 and outflow pipes 70 are regularly arranged as shown in FIG. Control rod assemblies 55 and outflow tubes 70 are arranged at a predetermined ratio with respect to fuel assemblies 50 .

The fuel assembly 50 is a fuel body in which a plurality of fuel rods are bundled. The individual fuel rods contain pelletized fuel within a tube. A plurality of fuel assemblies 50 are arranged in the core 5 as shown in FIG.

The control rod assembly 55 is for controlling the output of the fast reactor 1 with control rods 57 (FIG. 3). A plurality of control rod assemblies 55 are arranged dispersedly in the core 5, and specifically, arranged between a plurality of fuel assemblies 50 as shown in FIG. Control rod assembly 55 has control rods 57 and guide tubes 60 (FIG. 3). The control rod 57 controls nuclear fission, for example, by axially moving (here, moving up and down) in the guide tube 60 .

FIG. 3 is a schematic diagram for explaining the configuration of the guide tube 60. As shown in FIG. The guide tube 60 is cylindrical and accommodates the control rod 57 . The guide tube 60 guides the control rod 57 so that it can move up and down along the axial direction. As shown in FIG. 3, the guide pipe 60 is inserted into the connection pipe 11a of the diamond grid 11 and supported. A core catcher 21 (FIG. 1) is positioned below the connecting pipe 11a, although not shown in FIG.

By the way, in this embodiment, the guide pipe 60 has a function as a molten fuel outflow pipe through which the molten fuel in the core 5 flows out. For example, when a core damage accident occurs, a part of the peripheral wall of the guide tube 60 is fused by molten fuel, and the molten fuel flows into (intrudes into) the guide tube 60 from the fused portion. Molten fuel that has flowed into the guide pipe 60 falls inside and reaches the core catcher 21 . Thereby, the molten fuel can smoothly flow out to the core catcher 21 . The detailed configuration inside the guide tube 60 will be described later.

Returning to FIG. 2, the configuration of the outflow pipe 70 will be described. The outflow pipe 70 is a pipe for causing the molten fuel in the core 5 to flow out, like the guide pipe 60 described above. That is, when a core damage accident occurs, a part of the peripheral wall of the outflow pipe 70 is fused by the melted fuel, and the molten fuel flows into (intrudes into) the outflow pipe 70 from the fused part. Molten fuel that has flowed into the pipe falls inside the pipe and reaches the core catcher 21 .

A plurality of outflow pipes 70 are arranged dispersedly in the core 5 . Here, as shown in FIG. 2, a plurality of outflow pipes 70 are provided at the center and outer peripheral portions of the core 5, respectively. The arrangement of the outflow pipe 70 in the core 5 is not limited to the arrangement shown in FIG.

(Detailed configuration inside the guide pipe)
The detailed configuration inside the guide tube 60 will be described with reference to FIGS. 3 and 4. FIG.

FIG. 4 is a schematic diagram for explaining the cross-sectional configuration of the guide tube 60. As shown in FIG. In FIG. 3, coolant flow is indicated by dashed arrows. 3 is also a view taken along line AA in FIG.
The guide tube 60 has a cylindrical portion 61, a lower opening portion 63, an inflow portion 64, a flow path portion 65, a partition wall 67, and an upper opening portion 68, as shown in FIG.

The cylindrical portion 61 is a portion formed in a cylindrical shape. For example, the cylindrical portion 61 is formed in a hexagonal cylindrical shape as shown in FIG. The lower end side of the cylindrical portion 61 is inserted into the connecting pipe 11a of the diamond grid 11, as shown in FIG. The cylindrical portion 61 accommodates the control rods 57 of the fast reactor 1 . Here, the control rod 57 is accommodated on the upper side inside the cylindrical portion 61 . In addition, the inner region 62 of the cylindrical portion 61 is filled with a coolant.

The tubular portion 61 is adjacent to the heat generating region 5a (see FIG. 1) of the core 5. As shown in FIG. The cylindrical portion 61 can be fused by the heat of the molten fuel in the heat generating region 5a. That is, the peripheral wall of the tubular portion 61 is fused by the heat of the molten fuel. The axial upper end of the cylindrical portion 61 is located above the heat generating region 5a, and the axial lower end of the cylindrical portion 61 is located below the heat generating region 5a (see FIG. 1). Since the cylindrical portion 61 has the above positional relationship with respect to the heat generating region 5a, the portion of the cylindrical portion 61 adjacent to the heat generating region 5a is fused by molten fuel when the core is damaged. When the tubular portion 61 is fused by the molten fuel, the molten fuel flows into the tubular portion 61 from the fused portion.

The lower opening 63 is formed on the lower end side of the cylindrical portion 61 in the axial direction. Here, the lower opening 63 is formed on the central side of the lower end of the cylindrical portion 61 . The lower opening 63 communicates with the inner region 62 of the cylindrical portion 61 . Molten fuel that has flowed into the tubular portion 61 at the time of core damage flows out of the lower opening 63 via the inner region 62 . Therefore, the inner region 62 and the lower opening 63 serve as an outflow passage for the melted fuel that has flowed into the tubular portion 61 due to the blowout of the tubular portion 61 .

The inflow portion 64 is a portion that allows the coolant to flow into the cylindrical portion 61 . A high-pressure coolant sent to the diamond grid 11 by the pump 13 flows into the inflow portion 64 . As shown in FIG. 3, the inflow portion 64 is provided on the lower end side of the cylindrical portion 61 in the axial direction. The inflow portion 64 is formed on the outer peripheral surface of the cylindrical portion 61 here.

The channel portion 65 is connected to the inflow portion 64 . The flow path portion 65 is a portion in which the coolant that has flowed from the inflow portion 64 flows inside the cylinder portion 61 . As shown in FIG. 3, the flow path portion 65 is provided in the inner region 62 from the lower end side to the upper end side in the axial direction. As a result, the coolant that has flowed in from the inflow portion 64 flows upward through the flow path portion 65 .

The channel portion 65 is positioned around the control rod 57 as shown in FIG. A plurality of flow passage portions 65 are provided in the inner region 62 at predetermined intervals in the circumferential direction. A plurality of flow path portions 65 are branched on the way from the inflow portion 64 to the cylindrical portion 61 . As a result, the coolant that has flowed in from the inflow portion 64 flows upward through the flow passage portions 65 .

Each of the flow passages 65 is formed by a tube 65a having a triangular cross section. That is, a tube 65 a is provided in the interior region 62 . The plurality of tubes 65a are positioned at the corners of the hexagonal tubular portion 61 and are in contact with the inner wall surface 61a of the tubular portion 61 . As a result, the plurality of channel portions 65 can be efficiently arranged so as not to come into contact with the control rods 57 .

The partition wall 67 is provided on the upper end side inside the tubular portion 61 as shown in FIG. 3, and is connected to the upper end of the channel portion 65 here. The partition wall 67 divides the inner region 62 of the guide tube 60 into an upper region 62a and a lower region 62b. A flow path portion 65 is positioned in the lower region 62b. The upper region 62a communicates with the upper opening 68 of the cylinder.

The partition wall 67 has a first communication port 67a that communicates the channel portion 65 and the upper region 62a, and a second communication port 67b that communicates the upper region 62a and the lower region 62b. The first communication port 67 a is located on the edge side of the partition wall 67 , and the second communication port 67 b is located on the central side of the partition wall 67 . A first communication port 67 a is provided for each of the plurality of flow path portions 65 . The coolant that has flowed through the flow path portion 65 flows from the first communication port 67a to the upper region 62a. Part of the coolant that has flowed to the upper region 62a flows to the lower region 62b via the second communication port 67b. Thereby, the coolant is also supplied to the lower region 62b.

By providing the partition wall 67, the amount of the coolant that has flowed from the inflow portion 64 can be regulated to flow into the lower region 62b. Since the lower region 62b communicates with the lower opening 63, the coolant in the lower region 62b flows out to the lower plenum. Outflow can be suppressed.

The upper opening 68 is formed on the upper end side of the cylindrical portion 61 in the axial direction. Here, the upper opening 68 is formed on the central side of the upper end of the tubular portion 61 . An upper opening 68 allows the coolant in the communicating upper region 62a to flow out to the upper plenum.

(Outflow route of melted fuel)
The outflow of molten fuel through the guide tube 60 will be described with reference to FIG.
FIG. 5 is a schematic diagram for explaining an outflow route of molten fuel. In FIG. 5, the flow of molten fuel is indicated by thick arrows.

Here, it is assumed that core damage has occurred in the fast reactor 1, in which the fuel assemblies 50 (FIG. 2) melt due to overheating of the fuel. Then, the molten fuel in the fuel assembly 50 (heat generating region 5a) fuses the peripheral wall of the tubular portion 61 of the adjacent guide pipe 60 . For example, the molten fuel preferentially melts the portion of the peripheral wall of the cylindrical portion 61 that is not in contact with the flow path portion 65 (see FIG. 4).

When the peripheral wall of the tubular portion 61 is fused, molten fuel enters the tubular portion 61 via the fused portion (see FIG. 5). The molten fuel that has entered the cylindrical portion 61 falls down the inner region 62 (specifically, the lower region 62b) of the cylindrical portion 61 and flows out from the lower opening 63, as shown in FIG. The molten fuel flowing out from the lower opening 63 passes through the connection pipe 11a of the diamond grid 11 and reaches the core catcher 21 (FIG. 1). The molten fuel reaching the core catcher 21 is cooled by the core catcher 21 having a cooling function. This prevents molten fuel from melting the main vessel 3 of the fast reactor 1 and leaking to the outside when the core is damaged.

Although the channel portion 65 is formed of the pipe 65a having a triangular cross-sectional shape in the above description, the present invention is not limited to this. For example, the cross-sectional shape of the channel portion 65 may be the shape shown in FIG.

FIG. 6 is a schematic diagram for explaining a modification of the flow path portion 65. As shown in FIG. A flow path portion 65 shown in FIG. 6A is formed by a tube 65b having a circular cross-sectional shape. The tube 65b is provided at substantially the same position as the tube 65a described above. A flow path portion 65 shown in FIG. 6B is formed by contacting a corner portion of the cylindrical portion 61 with a plate member 65c extending in the axial direction.

(Effect in the first embodiment)
The guide pipe 60 of the above-described embodiment has a channel portion 65 provided in the inner region 62 of the cylindrical portion 61 from the lower end side to the upper end side and through which the inflowing coolant flows. The cylindrical portion 61 can be fused by the heat of the molten fuel in the adjacent heat generating region 5a. The inner region 62 and the lower opening 63 serve as an outflow passage through which melted fuel that has flowed into the cylindrical portion 61 due to the melting of the cylindrical portion 61 flows out.

With the above configuration, when the core is damaged, the peripheral wall of the cylindrical portion 61 is fused by the melted fuel in the heat generating region 5a. As a result, the melted fuel flows into the inner region 62 inside the tubular portion 61 from the fused portion, drops through the inner region 62 , and flows out from the lower opening 63 . In other words, the molten fuel can flow out from the lower opening 63 without any other member or the like in the cylindrical portion 61 . By using the guide tube 60 having the simple configuration as described above, it becomes possible to properly flow out the molten fuel when the core is damaged.

<Second embodiment>
In the first embodiment, the guide pipe 60 is described as the molten fuel outflow pipe, but in the second embodiment, the outflow pipe 70 has the function of the molten fuel outflow pipe.

The internal configuration of the outflow tube 70 will be described below with reference to FIGS. 7 to 9. FIG.
FIG. 7 is a schematic diagram for explaining the configuration of the outflow pipe 70. As shown in FIG. FIG. 8 is a schematic diagram for explaining the cross-sectional configuration of the outflow pipe 70. As shown in FIG. FIG. 9 is a schematic diagram for explaining an outflow route of molten fuel. 7 is also a view taken along line BB of FIG.

The outflow tube 70 of the second embodiment has the same configuration as the guide tube 60 described above, except that the control rod 57 is not accommodated. Specifically, as shown in FIG. 7, the outflow tube 70 has a cylinder portion 71, a lower opening portion 73, an inflow portion 74, a flow path portion 75, a partition wall 77, and an upper opening portion 78. . The tubular portion 71, the lower opening portion 73, the inflow portion 74, the flow passage portion 75, the partition wall 77, and the upper opening portion 78 are configured as the tubular portion 61, the lower opening portion 63, the inflow portion 64, and the flow passage portion of the guide tube 60, respectively. 65 , partition wall 67 and upper opening 68 . Therefore, like the guide tube 60, the outflow tube 70 can appropriately flow out the molten fuel in the heat generating region 5a when the core is damaged.

Specifically, the molten fuel in the heat generating region 5a fuses the peripheral wall of the cylindrical portion 71 of the adjacent outflow pipe 70 . When the peripheral wall of the tubular portion 71 is fused, the molten fuel enters the tubular portion 71 via the fused portion (see FIG. 9). The molten fuel that has entered the cylindrical portion 71 drops down the inner region 72 of the cylindrical portion 71 and flows out from the lower opening portion 73 . The coolant flowing out from the lower opening 73 passes through the connection pipe 11 a of the diamond grid 11 and reaches the core catcher 21 .

By the way, the plurality of flow passage portions 75 shown in FIG. 8 are formed of pipes 75a having a triangular cross section and are in contact with the inner wall surface 71a of the cylindrical portion 71, but are not limited to this. The channel portion 75 may be provided as shown in FIG. 10, for example.

FIG. 10 is a schematic diagram for explaining a modification of the flow path portion 75. As shown in FIG. In the modified example, one channel portion 75 is provided, which is formed of a pipe 75b having a circular cross section. The flow path portion 75 is positioned apart from the inner wall surface 71 a of the tubular portion 71 . As a result, the molten fuel in the heat generating region 5 a can be fused along the entire circumference of the cylindrical portion 71 and easily flows into the cylindrical portion 71 .
In addition, one flow path part 65 may be provided also in 1st Embodiment mentioned above. Further, the channel portion 65 may be separated from the inner wall surface 61 a of the cylindrical portion 61 .

In the above-described embodiment, the case where one of the guide pipe 60 and the outflow pipe 70 functions as the molten fuel outflow pipe has been described, but the present invention is not limited to this. For example, in one fast reactor 1, both the guide pipe 60 and the outflow pipe 70 may function as molten fuel outflow pipes.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist thereof. be. For example, all or part of the device can be functionally or physically distributed and integrated in arbitrary units. In addition, new embodiments resulting from arbitrary combinations of multiple embodiments are also included in the embodiments of the present invention. The effect of the new embodiment caused by the combination has the effect of the original embodiment.

1 Fast Reactor 5 Core 5a Heat Generation Area 60 Guide Tube 61 Cylinder Part 62 Internal Area 62a Upper Area 62b Lower Area 63 Lower Opening 65 Channel Part 67 Partition Wall 67a First Communication Port 67b Second Communication Port 70 Outflow Pipe 71 Cylinder Portion 72 inner region 72a upper region 72b lower region 73 lower opening 75 channel portion 77 partition

Claims (6)

A molten fuel outflow pipe of a fast reactor provided in the core of the fast reactor,
a cylindrical portion having an inner region filled with a coolant and adjacent to the heat generating region of the core;
a lower opening formed at the lower end side of the cylindrical portion in the axial direction;
a channel portion provided from the lower end side to the upper end side in a state in which a wall is interposed between the cylindrical portion and the inner region, and through which the inflowing coolant flows;
with
The cylindrical portion can be fused by the heat of the molten fuel in the heat generating region,
The inner region and the lower opening serve as an outflow path for outflowing the molten fuel that has flowed into the cylindrical portion due to fusion cutting of the cylindrical portion.
Molten fuel outflow tube of a fast reactor. The cylindrical portion accommodates a control rod of the fast reactor,
The flow path portion is positioned around the control rod,
A molten fuel outflow tube for a fast reactor according to claim 1. A plurality of the flow passage portions are provided in the inner region at predetermined intervals in the circumferential direction,
3. The molten fuel outflow pipe for a fast reactor according to claim 1 or 2. The flow path portion is positioned apart from the inner wall surface of the tubular portion,
A molten fuel outflow pipe for a fast reactor according to any one of claims 1 to 3. further comprising a partition wall provided on the upper end side in the cylindrical portion and dividing the inner region into an upper region and a lower region;
The partition wall has a first communication port that communicates the channel portion and the upper region, and a second communication port that communicates the upper region and the lower region.
A molten fuel outflow pipe for a fast reactor according to any one of claims 1 to 4. A fast reactor in which a plurality of molten fuel outflow tubes are dispersedly arranged in the core,
The molten fuel outflow pipe is
a cylindrical portion having an inner region filled with a coolant and adjacent to the heat generating region of the core;
a lower opening formed at the lower end side of the cylindrical portion in the axial direction;
a channel portion provided from the lower end side to the upper end side in a state in which a wall is interposed between the cylindrical portion and the inner region, and through which the inflowing coolant flows;
with
an upper end of the cylindrical portion in the axial direction is positioned above the heat generating region;
a lower end of the cylindrical portion in the axial direction is positioned below the heat generating region;
The cylindrical portion can be fused by the heat of the molten fuel in the heat generating region,
The inner region and the lower opening serve as an outflow path for outflowing the molten fuel that has flowed into the cylindrical portion due to fusion cutting of the cylindrical portion.
fast reactor.

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