JPH07140278A - Fast breeder reactor - Google Patents

Abstract

PURPOSE:To provide a fast breeder reactor able to reduce temperature difference between a cooling fluid and a plenum fluid when the cooling fluid of reactor wall cooling mechanism is discharged to a high temperature plenum and a low temperature plenum. CONSTITUTION:A cooling fluid flowing in from a low temperature plenum 5 flows upward along the reactor wall 3A by an up-passage 11, flows over a liner plate 21 to flow into a down-passage 12 so as to flow downward, and flows into an intermediate passage 13 from an opening part 22a so as to be led into an intermediate plenum 4 from an opening part 23a. The cooling fluid is then led into a heat exchanging passage 15 from the intermediate plenum 4 to exchange heat with a fluid filled in a high temperature plenum 6 through a liner plate 24, and after temperature rise, discharged to a high temperature plenum 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fast breeder reactor, and more particularly to a fast breeder reactor using liquid metal sodium as a coolant.

[0002]

2. Description of the Related Art In a fast breeder reactor in which liquid metal is used as a coolant, liquid metal sodium (hereinafter,
It is called sodium as appropriate) is most often used.

In general, a fast breeder reactor using liquid metal sodium as a coolant has a reactor vessel filled with sodium, a core disposed inside the reactor vessel, and a high temperature at the core outlet during normal rated operation. The intermediate plenum that separates sodium from the low temperature sodium at the core inlet, the low temperature plenum that is provided below the intermediate plenum, the high temperature plenum that is provided above the intermediate plenum, and the reactor vessel wall from the high temperature of the high temperature plenum Cooling mechanism of the reactor vessel provided inside the reactor vessel for protection (hereinafter, as appropriate,
Furnace wall cooling mechanism). The fast breeder reactor
A roof deck that is an upper lid that closes the upper part of the reactor vessel,
A reactor top mechanism fixed to the roof deck and located above the core, a pipe penetrating the roof deck to take out high temperature sodium from the high temperature plenum to the outside, and a pipe penetrating the roof deck to cool from outside It has a pipe for introducing sodium into the low temperature plenum, and a high pressure plenum provided below the core and connected to the pipe.

In the above structure, during normal rated operation, the high temperature sodium in the high temperature plenum is taken out to the external heat exchanger via the pipe and cooled to become the low temperature sodium, and the high pressure plenum and the low temperature plenum are passed through the pipe by the external pump. Is sent to the high temperature plenum, where it rises to cool the core and heat itself.

The structure near the furnace wall cooling mechanism is, for example,
As described in U.S. Pat. No. 4,477,410, there is a configuration in which three cooling flow passages partitioned by a liner plate are provided inside the wall of the reactor vessel. That is, the cooling fluid is first introduced from the high-pressure plenum to the low-temperature plenum, then rises along the wall of the reactor vessel along the outermost (reactor wall side) cooling flow path from the low-temperature plenum to cool the wall surface of the reactor vessel. Further, in the upper part of the cooling flow path, it overflows the boundary surface with the cooling flow path provided further inside, flows into the cooling flow path inside thereof, and descends the cooling flow path inside thereof. After that, it enters the intermediate plenum through the lower part of the cooling passage provided further inside, and is discharged to the high temperature plenum from the discharge part provided at the upper part of the intermediate plenum.

As another example of the structure near the reactor wall cooling mechanism, for example, as described in US Pat. No. 4,167,445, two cooling flow passages and an intermediate portion which are partitioned by a liner plate are provided inside the wall of the reactor vessel. There is a structure in which a stop layer connected to the plenum is provided. That is, the cooling fluid first rises from the bottom of the high-pressure plenum to the outermost (reactor wall side) cooling channel along the wall of the reactor vessel to cool the wall surface of the reactor vessel, and then at the upper part of the cooling channel of the cooling channel. It flows over the boundary surface with the cooling flow path provided inside, flows into the cooling flow path inside thereof, descends through the cooling flow path, and then is discharged from below and discharged to the low temperature plenum.

[0007]

However, the above-mentioned known techniques have the following problems. That is, regarding the furnace wall cooling mechanism of the fast breeder reactor, US Pat.
In the structure described in No. 0, the fluid that has cooled the furnace wall is discharged directly from the discharge part of the intermediate plenum to the high temperature plenum. At this time, the difference T _H −T between the temperature T of the fluid discharged and the temperature T _H of the high temperature fluid of the high temperature plenum is close to 150 K, so a structure that can withstand thermal fatigue due to this temperature difference near the discharge part. A material must be used, which is not preferable in terms of strength and cost. Also US Pat.
In the structure of the furnace wall cooling mechanism described in No. 5, the fluid that cools the furnace wall and is heated by itself is discharged to the low temperature plenum directly from the cooling channel provided inside the outermost cooling channel. It At this time, the difference T- _TL between the temperature T of the fluid discharged and the temperature _TL of the low temperature fluid in the low temperature plenum is close to 100K, which is not preferable in terms of strength and cost as in the above.

An object of the present invention is when the cooling fluid of the furnace wall cooling mechanism is discharged to the hot plenum or the cold plenum,
It is an object of the present invention to provide a fast breeder reactor capable of reducing a temperature difference between a cooling fluid and a plenum fluid.

[0009]

In order to achieve the above object, according to the present invention, a reactor vessel filled with a primary coolant, a reactor core arranged inside the reactor vessel, and A low temperature plenum provided in the lower part of the reactor vessel, a high temperature plenum provided in the upper part of the reactor vessel, and the primary coolant provided in the lower part of the reactor vessel is taken into the low temperature plenum from outside the reactor. A high pressure plenum connected to the pipe and a cooling fluid from the high pressure plenum provided inside the reactor wall of the reactor vessel are introduced to cool the reactor wall to cool the cooling fluid to one of the high temperature plenum and the low temperature plenum. In a fast breeder reactor having a reactor vessel cooling mechanism for discharging, the reactor vessel cooling mechanism is at an outlet portion where the cooling fluid is discharged to one of the high temperature plenum and the low temperature plenum, Fast breeder reactor characterized by having a heat exchange passage for heat exchange with the serial filled inside one of the cooling fluid the hot plenum and the cold plenum fluid.

Further, in order to achieve the above object, according to the present invention, a reactor vessel filled with a primary coolant, a core arranged inside the reactor vessel, and a lower portion of the reactor vessel A low temperature plenum provided in the reactor vessel, a high temperature plenum provided in the upper portion of the reactor vessel, and a pipe provided in the lower portion of the reactor vessel to take the primary coolant from outside the reactor into the low temperature plenum. A high pressure plenum, and a reactor provided on the inner side surface of the reactor wall of the reactor vessel for guiding a cooling fluid from the high pressure plenum through the low temperature plenum to cool the reactor wall and discharge the cooling fluid to the high temperature plenum. In a fast breeder reactor having a vessel cooling mechanism, the reactor vessel cooling mechanism includes the cooling fluid and the high temperature plenum at an outlet portion where the cooling fluid is discharged to the high temperature plenum. Fast breeder reactor characterized by having a heat exchange passage is provided for heat exchange with the filled fluid to part.

To further achieve the above object, according to the present invention, a reactor vessel filled with a primary system coolant, a reactor core disposed inside the reactor vessel, and a lower portion of the reactor vessel A low temperature plenum provided in the reactor vessel, a high temperature plenum provided in the upper portion of the reactor vessel, and a pipe provided in the lower portion of the reactor vessel to take the primary coolant from outside the reactor into the low temperature plenum. A high pressure plenum and a reactor vessel cooling that is provided on the inner bottom surface and inner side surface of the reactor wall of the reactor vessel, introduces a cooling fluid from the high pressure plenum, cools the reactor wall, and discharges the cooling fluid to the low temperature plenum. In the fast breeder reactor having a mechanism, the reactor vessel cooling mechanism is filled in the cooling fluid and the inside of the low temperature plenum at an outlet portion where the cooling fluid is discharged to the low temperature plenum. Fast breeder reactor is provided characterized by having a heat exchange passage for heat exchange with the fluid.

[0012] Preferably, in the fast breeder reactor, the reactor vessel cooling mechanism is provided on the most reactor wall side in the reactor vessel, and the cooling fluid flowing from the low temperature plenum is moved upward along the reactor wall. An ascending flow path that flows into the ascending flow path, a descending flow path that is provided inside the ascending flow path and that causes the cooling fluid that flows from near the upper end of the ascending flow path to flow downward, and a descending flow path that is provided inside the descending flow path. An intermediate flow passage for guiding the cooling fluid flowing from near the lower end of the passage to an intermediate plenum provided between the low temperature plenum and the high temperature plenum, and the heat exchange passage is provided above the intermediate plenum. A fast breeder reactor is provided which is provided inside the intermediate flow path and is an ascending flow path for guiding the cooling fluid flowing from the intermediate plenum to the high temperature plenum.

Further preferably, in the fast breeder reactor, the reactor vessel cooling mechanism is provided on the most reactor wall side in the reactor vessel, and the cooling fluid flowing from the low temperature plenum along the reactor wall. A first ascending flow path that flows upward, and a descending flow path that is provided inside the first ascending flow path and that causes the cooling fluid that flows from near the upper end of the first ascending flow path to flow downward The heat exchange flow passage is provided inside the descending flow passage, and a second ascending flow passage is provided for flowing upward the cooling fluid that has flowed in from near the lower end of the descending flow passage, and the second ascending flow passage. And a discharge port provided on the partition surface between the high temperature plenum and the high temperature plenum.

More preferably, in the fast breeder reactor, the reactor vessel cooling mechanism is provided on the most reactor wall side in the reactor vessel, and the cooling fluid flowing from the low temperature plenum is passed along the reactor wall. An ascending flow path that flows upward, a descending flow path that is provided inside the ascending flow path and that causes the cooling fluid that flows from near the upper end of the ascending flow path to flow downward, and a descending flow path that is provided inside the descending flow path. An intermediate flow path for guiding the cooling fluid flowing from near the lower end of the flow path to an intermediate plenum provided between the low temperature plenum and the high temperature plenum, and the heat exchange flow path has a lower end of the intermediate flow path. A fast breeder reactor is provided that has at least one conduit near the top surface of the plenum and having an upper end projecting into the hot plenum.

Further preferably, in the fast breeder reactor, the reactor vessel cooling mechanism is provided on the most reactor wall side in the reactor vessel, and causes the cooling fluid flowing from the high pressure plenum to flow along the reactor wall. The heat exchange flow has an upward flow path that flows upward, and a first downward flow path that is provided inside the upward flow path and that flows downward the cooling fluid that has flowed from near the upper end of the upward flow path. The passage is a second descending passage that is provided inside the ascending passage below the first descending passage and that guides the cooling fluid flowing from the first descending passage to the low temperature plenum. A featured fast breeder reactor is provided.

More preferably, in the fast breeder reactor, the reactor vessel cooling mechanism is provided on the most reactor wall side in the reactor vessel, and the cooling fluid flowing from the high pressure plenum along the reactor wall. And an ascending flow path that flows upward, and a descending flow path that is provided inside the ascending flow path and that causes the cooling fluid that has flowed in from near the upper end of the ascending flow path to flow downward, and that the heat exchange flow path is A fast breeder reactor is provided inside the ascending passage below the descending passage and is a horizontal passage that guides the cooling fluid flowing from the descending passage to the low temperature plenum. It

Further, preferably, in the fast breeder reactor, the first partition surface between the intermediate flow path and the heat exchange flow path and the second partition surface between the heat exchange flow path and the high temperature plenum. In a horizontal cross section, each of them forms a circle concentric with the reactor wall of the reactor vessel, and the heat exchange flow passage forms an annular space sandwiched between the first partition surface and the second partition surface. A fast breeder reactor is provided.

More preferably, in the fast breeder reactor, the third partition surface between the descending passage and the heat exchange passage, and the fourth partition surface between the heat exchange passage and the high temperature plenum. Each has a circle concentric with the reactor wall of the reactor vessel in a horizontal cross section, and the heat exchange channel forms an annular space sandwiched between the third partition surface and the fourth partition surface. A fast breeder reactor is provided.

Further preferably, in the fast breeder reactor, a fifth partition surface between the ascending passage and the descending passage,
The heat exchange passage and the sixth partition surface of the low temperature plenum form a circle concentric with the reactor wall of the reactor vessel in a horizontal cross section, and the heat exchange passage has a fifth partition surface and a fifth partition surface. There is provided a fast breeder reactor, which is characterized by forming an annular space sandwiched between 6 partition surfaces.

[0020]

In the present invention configured as described above, the heat of the cooling fluid and the fluid in the high temperature / low temperature plenum is generated in the heat exchange passage provided at the outlet of the reactor vessel cooling mechanism where the cooling fluid is discharged. By performing the exchange, when the cooling fluid is discharged to the high temperature plenum, it is discharged after being heated in the heat exchange passage before being discharged, and when the cooling fluid is discharged to the low temperature plenum, before being discharged. The temperature of the cooling fluid and that of the fluid in the high-temperature and low-temperature plenums is higher than that of the conventional reactor vessel cooling mechanism that does not have a heat-exchange passage because it is discharged after being cooled in the heat-exchange passage in advance. The difference can be reduced.

Further, in the present invention, the heat is exchanged between the cooling fluid and the fluid in the high temperature plenum in the heat exchange passage provided in the outlet portion of the reactor vessel cooling mechanism where the cooling fluid is discharged. Since it is discharged after being heated in advance in the heat exchange flow path, the cooling fluid temperature T and the fluid temperature in the high temperature plenum that were close to 150 K when discharged from a conventional reactor vessel cooling mechanism without a heat exchange flow path the difference between the T _H T _H -
T can be reduced.

Further, according to the present invention, the heat is exchanged between the cooling fluid and the fluid in the low temperature plenum in the heat exchange passage provided in the outlet portion of the reactor vessel cooling mechanism where the cooling fluid is discharged. Since it is discharged after being previously cooled in the heat exchange channel, the cooling fluid temperature T and the fluid temperature in the low temperature plenum that were close to 100K when discharged from the conventional reactor vessel cooling mechanism in the heat exchange channel the difference T-T _L and T _L
Can be reduced.

Further, as an example of the structure of the reactor vessel cooling mechanism, the cooling fluid is caused to flow upward along the reactor wall in the ascending passage provided on the most reactor wall side in the reactor vessel, and the ascending passage is further provided. The cooling fluid is made to flow downward in the descending passage provided inside the
Further, the cooling fluid is guided to the intermediate plenum by the intermediate flow passage provided inside the descending flow passage, and the cooling fluid is discharged to the high temperature plenum by the heat exchange flow passage provided inside the intermediate flow passage above the intermediate plenum. Or, the cooling fluid flows upward along the furnace wall in the first ascending passage provided closest to the reactor wall in the reactor vessel, and further the descending passage provided inside the first ascending passage. To flow the cooling fluid downward, and further to flow the cooling fluid upward in the second ascending passage of the heat exchanging passage provided inside the descending passage, and at the outlet of the heat exchanging passage provided at the partition surface. To discharge the cooling fluid to the high temperature plenum, or to make the cooling fluid flow upward along the reactor wall in the rising passage provided on the most reactor wall side in the reactor vessel, and to be installed inside the rising passage. Cooling fluid flows downward in the descending flow path,
Further, the cooling fluid is guided to the intermediate plenum by the intermediate flow passage provided inside the descending flow passage, and further, the lower end is near the upper surface of the intermediate plenum and the upper end is a pipe that projects into the high temperature plenum. The cooling fluid is discharged from the high temperature plenum, or the cooling fluid is caused to flow upward along the reactor wall in the ascending passage provided on the most reactor wall side in the reactor vessel, and is further provided inside the ascending passage. The cooling fluid is made to flow downward in the first descending passage, and the cooling fluid is cooled to a low temperature in the heat exchanging passage which is the second descending passage provided inside the ascending passage below the first descending passage. A structure in which the cooling fluid is discharged to the plenum, or the cooling fluid flows upward along the furnace wall in the ascending flow path provided on the most reactor wall side in the reactor vessel, and the descending flow path is provided inside the ascending flow path. Flow the cooling fluid downward, and then the ascending flow below the descending flow path. There is a configuration in which the discharging horizontal flow path exiting the heat exchange passage in the cooling fluid provided inside the low-temperature plenum.

Further, as an example of the structure of the heat exchange passage, the first partition surface between the intermediate passage and the heat exchange passage forming a circle concentric with the reactor wall of the reactor vessel in the horizontal section and the heat exchange passage.・ The structure is such that it is sandwiched between the second partition surfaces between the high temperature plenums to form an annular space, or the first passage between the descending passage and the heat exchanging passage forming a circle concentric with the reactor wall of the reactor vessel in the horizontal cross section No. 3 partition surface and the fourth partition surface between the heat exchange passage and the high-temperature plenum to form an annular space, or in a horizontal cross section, rise in a circle concentric with the reactor wall of the reactor vessel. There is a configuration in which an annular space is formed by being sandwiched between the fifth partition surface between the flow path and the descending flow path and the sixth partition surface between the heat exchange flow path and the low temperature plenum.

[0025]

Embodiments of the present invention will be described below with reference to FIGS. A first embodiment of the present invention will be described with reference to FIGS. The fast breeder reactor of this example is shown in FIG. In FIG. 2, the fast breeder reactor according to the present embodiment includes a reactor vessel 3 filled with sodium, a core 1 disposed inside the reactor vessel 3, and a low temperature plenum provided below the reactor vessel 3. 5
And a high temperature plenum 6 provided on top of the reactor vessel 3.
And an intermediate plenum 4 for separating high temperature sodium at the core 1 outlet and low temperature sodium at the core inlet 1 during normal rated operation, and sodium provided at the bottom of the reactor vessel 3 to the low temperature plenum 5 from outside the reactor. Piping 9
And a high pressure plenum 16 provided below the core 1 and connected to the piping 9, and a cooling fluid is guided from the high pressure plenum 16 provided on the inner side surface of the reactor wall of the reactor vessel 3 via the low temperature plenum 5 to the reactor wall. A furnace wall cooling mechanism 10 for cooling and discharging the cooling fluid to the high temperature plenum 6.

Further, the fast breeder reactor is a roof deck 7 which is an upper lid for closing the upper part of the reactor vessel 3, and a reactor upper mechanism 2 which is fixed to the roof deck 7 and is located above the core 1.
And a high temperature plenum 6 which is provided so as to penetrate the roof deck 7.
And a pipe 8 for taking out high temperature sodium from the outside.

In the above structure, the flow of liquid sodium as the primary coolant is such that during normal rated operation, the high temperature sodium in the high temperature plenum 6 is taken out to the external heat exchanger via the pipe 8 and cooled to become low temperature sodium, It is sent to the high-pressure plenum 16 and the low-temperature plenum 5 via the pipe 9 by an external pump, rises, cools the core 1, is heated by itself, and flows out to the high-temperature plenum 6.

Next, FIG. 1 shows a detailed structure of the furnace wall cooling mechanism 10 which is a main part of this embodiment. In FIG. 1, the furnace wall cooling mechanism 10 includes an ascending flow path 11 provided on the most reactor wall 3A side in the reactor vessel 3 and an inside of the ascending flow path 11 (left side in the drawing).
And the intermediate flow path 13 provided inside the down flow path 12 (on the left side in the drawing). Further, the furnace wall cooling mechanism 10 has a heat exchange flow path 15 at an outlet portion where the cooling fluid is discharged to the high temperature plenum 6. Heat exchange channel 1
The reference numeral 5 is provided above the intermediate plenum 4 and inside the intermediate flow passage 13, and forms an ascending flow passage for guiding the cooling fluid flowing from the intermediate plenum 4 to the high temperature plenum 6. At this time, the liner plate 23, which is a partition surface between the intermediate flow path 13 and the heat exchange flow path 15, and the liner plate 24, which is a partition surface between the heat exchange flow path 15 and the high temperature plenum 6, each have a horizontal cross section (FIG. The reactor vessel 3 in
It forms a circle concentric with the furnace wall 3A. That is, the heat exchange channel 1
Reference numeral 5 forms an annular space sandwiched between the liner plate 23 and the liner plate 24.

In the structure of the furnace wall cooling mechanism 10 described above, the cooling fluid introduced from the high pressure plenum 16 through the low temperature plenum 5 and flowing into the ascending passage 11 is caused by the ascending passage 11 as shown by → in the figure. It flows upward along the furnace wall 3A, flows over the liner plate 21 from the vicinity of the upper end of the ascending flow path 11, and flows into the descending flow path 12. Further, the cooling fluid flowed downward by the descending passage 12 flows into the intermediate passage 13 from the opening 22 a of the liner plate 22 near the lower end of the descending passage 12. Further, the intermediate flow path 13 is filled with the stagnant fluid, and the cooling fluid flowing from the descending flow path 12 into the intermediate flow path 13 traverses a lower portion of the stagnant fluid 1 and the intermediate flow path 1
3 is guided to the intermediate plenum 4 from the opening 23 a of the liner plate 23 near the lower end of the liner 3. And the cooling fluid is the intermediate plenum 4
Is guided to the heat exchange flow passage 15 and exchanges heat with the fluid filled in the high temperature plenum 6 via the liner plate 24 in the heat exchange flow passage 15 to cool the fluid in the high temperature plenum 6 and After being heated and heated, it is discharged to the high temperature plenum 6.

Next, the operation of this embodiment will be described with reference to FIGS. As a comparative example of this embodiment, a furnace wall cooling mechanism 810 of a conventional fast breeder reactor is shown in FIG. Figure 1
Parts common to those of the present embodiment shown in FIG. 3 is different from the furnace wall cooling mechanism 10 of this embodiment shown in FIG.
The intermediate plenum 8 through the descending flow path 812 and the intermediate flow path 813.
That is, the cooling fluid that has flowed into 04 is immediately discharged to the high temperature plenum 806, which is an upper opening of the intermediate plenum 804, from the discharge portion 814. Thus, the difference T _H -T between the temperature T _H of the hot fluid temperature T and the hot plenum of the fluid to be discharged becomes near 150K,
A structural material capable of withstanding thermal fatigue due to this temperature difference must be used near the discharge part, which is not preferable in terms of strength and cost.

However, in the furnace wall cooling mechanism 10 of the present embodiment shown in FIG. 1, the cooling fluid and the high temperature plenum 6 are provided in the heat exchange passage 15 provided at the outlet portion where the cooling fluid is discharged to the high temperature plenum 6. By exchanging heat with the fluid inside, the cooling fluid is heated in advance in the heat exchange passage 15 and then discharged, so that the conventional furnace wall cooling mechanism 810 (see FIG. 3) having no heat exchange passage is used. it is possible to reduce the difference T _H -T between the cooling fluid temperature T and the hot plenum fluid temperature T _H than when discharged. This will be described in more detail with reference to FIG.

[0032] in the case of changing the vertical length of the heat exchange passage 15, the change of the difference T _H -T between the cooling fluid temperature T and the hot plenum 6 in fluid temperature T _H of the heat exchange passage 15 outlet Is shown in FIG. Here, in FIG. 4, the inner diameter of the heat exchange channel 15 (the distance of the liner plate 24 from the axis of the reactor vessel 3) is set to 1
0 m, outer diameter (distance of the liner plate 23 from the axis of the reactor vessel 3) is 10.1 m (that is, the width of the heat exchange passage 15 is 0.1 m).
05m), and the plate thickness of the constituent material of the heat exchange channel 15 is 5m.
m, the flow rate of the cooling fluid flowing into the heat exchange passage 15 is 100
kg / s, the temperature difference between the fluid in the high temperature plenum 6 and the cooling fluid at the inlet of the heat exchange passage 15 is 150K, the heat transfer rate from the high temperature plenum 6 to the heat exchange passage through the liner plate 24 is The value when estimated to be 2000 W / m ² K is shown. The vertical axis, the temperature difference T _H -T, discharge portion 8 of the intermediate plenum 804 without heat exchange passage prior art (see FIG. 3)
Temperature difference T _H -To the cooling fluid temperature To and T _H in 14
In shown in dimensionless value _{(T H -T) / (T} H -To). Figure 4
In, the longer the vertical length of the heat exchange passage 15 is,
(T _H -T) / value of (T _H -To) is decreased, the heat exchange passage 15
Cooling fluid temperature T at outlet and fluid temperature T in high temperature plenum 6
It can be seen that the difference from _H is reduced. That is, for example,
In the case where the vertical length of the heat exchange passage 15 was set to 3m is _{(T H -T) / (T} H -To) ≒ 0.2 , and the temperature T and the hot plenum 6 of the cooling fluid discharged Fluid temperature _TH
The difference T _H -T is when there is no heat exchange passage 15 the temperature difference T _H between the
-It can be reduced to about 20% of To.

As described above, according to the fast breeder reactor of this embodiment, the heat exchange flow passage 15 provided at the outlet portion where the cooling fluid of the furnace wall cooling mechanism 10 is discharged to the high temperature plenum 6.
Since the cooling fluid and the fluid in the high temperature plenum 6 are heat-exchanged with each other, the temperature of the cooling fluid and the high temperature plenum are higher than those in the case where the cooling fluid is discharged from the furnace wall cooling mechanism 810 having no heat exchange passage in the conventional fast breeder reactor. The difference from the internal fluid temperature is, for example, 2
To about 0% from _{(T H -To ≒ 150K T H} -T ≒ 30K
Can be reduced. Therefore, the strength condition of the structural material used near the outlet portion is relaxed, and even when the same structural material as the conventional one is used, the strength is improved and the life is extended, so that the cost can be reduced.

A second embodiment of the present invention will be described with reference to FIG. This example is an example of a fast breeder reactor having different furnace wall cooling mechanisms. The furnace wall cooling mechanism of the fast breeder reactor of this embodiment is shown in FIG. Parts common to the first embodiment are designated by common numbers. In FIG. 5, the furnace wall cooling mechanism 210 in the present embodiment differs from the furnace wall cooling mechanism 10 in the first embodiment in that inside the descending flow path 12 (left side in the figure), not the intermediate flow path, but the heat exchange flow. A passage 215 is provided so that the cooling fluid flows from the descending passage 12 through the opening 22 a to the heat exchange passage 2
It is to flow into 15. That is, the heat exchange channel 215
Is an ascending flow path 213 that is provided inside the descending flow path 12 and that causes a cooling fluid to flow upward, and an exhaust port 224a that is provided in a liner plate 224 that is a partition surface between the heat exchange flow path 215 and the high temperature plenum 6. The cooling fluid has heat exchange with the fluid in the high temperature plenum 6 via the liner plate 224, and then the discharge port 22.
4a is discharged to the high temperature plenum 6. Also at this time,
The liner plate 22 and the liner plate 224, which are the partition surfaces of the descending flow path 12 and the heat exchange flow path 215, are respectively separated from the reactor wall 3A of the reactor vessel 3 in a horizontal cross section (a cross section along a straight line in the horizontal direction in the drawing). The heat exchange flow paths 215 form concentric circles, and form an annular space sandwiched between the liner plate 22 and the liner plate 224. Other configurations in this embodiment are almost the same as those in the first embodiment.

In the above, the inner diameter of the heat exchange passage 215 (the distance of the liner plate 224 from the axis of the reactor vessel 3) is 9.9 m, and the outer diameter (the distance of the liner plate 22 from the axis of the reactor vessel 3). The distance) is 10 m (that is, the channel width is 0.05 m), the plate thickness of the constituent material of the heat exchange channel 215 is 5 mm, and the heat exchange channel 2 is
The flow rate of the cooling fluid flowing into 15 is 100 kg / s, the temperature difference between the fluid in the high temperature plenum 6 and the cooling fluid at the inlet of the heat exchange passage 215 is 150 K, and the liner plate 22
Estimating the heat transfer rate from the high temperature plenum 6 to the heat exchange flow path through 2000 is 2000 W / m ² K, the heat exchange flow path 2 when the vertical length of the heat exchange flow path 215 is changed.
Change in the difference T _H -T between the cooling fluid temperature T and the hot plenum 6 in fluid temperature T _H of 15 outlet portion becomes substantially the same as FIG. 4, for example, the vertical length of the heat exchange passage 215 was 3m _{If, (T H -T) / (} T H -To) ≒ 0.2 , and the temperature T _H of the fluid temperature T and the hot plenum 6 of the cooling fluid discharged
The difference between T _H -T can be reduced to approximately 20% of the temperature difference T _H -To in the absence of heat exchange passage 215. That is,
According to this embodiment, the same effect as that of the first embodiment can be obtained.

A third embodiment of the present invention will be described with reference to FIG. This example is an example of a fast breeder reactor having different furnace wall cooling mechanisms. FIG. 6 shows the furnace wall cooling mechanism of the fast breeder reactor of this embodiment. Parts common to those of the first and second embodiments are designated by common numbers. In FIG. 6, the furnace wall cooling mechanism 310 in the present embodiment is different from the furnace wall cooling mechanism 10 in the first embodiment in that an ascending flow path is provided inside the intermediate flow path 13 as a heat exchange flow path. In the heat exchange flow passage 315 of the present embodiment, at least one pipe (the three pipes 315a to 315c in this embodiment are provided with the lower end near the upper surface of the intermediate plenum 4 and the upper end protruding into the high temperature plenum 6). It is to have a set of several places).
That is, the cooling fluid flows from the vicinity of the upper surface of the intermediate plenum 4 into the three pipes 315a to 315c as the heat exchange flow passage 315, and the fluid in the high temperature plenum 6 passes through the respective pipe walls of these pipes 315a to 315c. After exchanging heat with the above, it is discharged to the high temperature plenum 6. The other structure is almost the same as that of the first embodiment.

In the above, as the heat exchange flow passage 315, a tube bundle having seven pipe passages each having an inner diameter of 0.3 m and a plate thickness of 5 mm as one set is protruded into the high temperature plenum 6 and provided at four places. The flow rate of the inflowing cooling fluid is 100 kg / s, the temperature difference between the fluid in the high temperature plenum 6 and the cooling fluid at the inlet of the heat exchange passage 315 is 150 K, and the high temperature plenum via the tube walls of the four tube bundles is used. 6 to heat exchange channel 315
It is estimated as 1500 W / m ² K The heat transfer coefficient for the change of the difference T _H -T between the cooling fluid temperature T and the hot plenum 6 in fluid temperature T _H of the heat exchange passage 315 outlet portion approximately the 4 showed the same trend, for instance, when the vertical length of the tube one used for the heat exchange passage 315 is _{4.5m, (T H -T) /} (T H -To) ≒
The difference T _H −T between the temperature T of the discharged cooling fluid and the temperature T _H of the fluid in the high temperature plenum 6 becomes 0.2.
15 can be reduced to about 20% of the temperature difference T _H -To in the absence. That is, according to this embodiment, the same effect as that of the first embodiment can be obtained.

A fourth embodiment of the present invention will be described with reference to FIG. This example is an example of a fast breeder reactor having different furnace wall cooling mechanisms. FIG. 7 shows the furnace wall cooling mechanism of the fast breeder reactor of this embodiment. Parts common to those of the first to third embodiments are designated by common numbers. In FIG. 7, a reactor wall cooling mechanism 410 is provided on the inner bottom surface and inner side surface of the reactor wall 403A of the reactor vessel 403, guides the cooling fluid from the high pressure plenum 416, cools the reactor wall 403A, and supplies the cooling fluid to the low temperature plenum 405. It is to be discharged, and has an ascending flow path 411 provided on the most furnace wall 403A side in the reactor vessel 403 and a descending flow path 412 provided inside the ascending flow path 411 (left side in the figure). Further, the furnace wall cooling mechanism 410 has a heat exchange flow passage 415 at the outlet portion where the cooling fluid is discharged to the low temperature plenum 405. The heat exchange flow path 415 is the downflow path 4
12 is provided inside the ascending flow path 411 below the cooling flow plenum 40.
5, a descending flow path leading to No. 5 is formed. At this time, the liner plate 42 which is a partition surface between the ascending flow path 411 and the descending flow path 412.
1 and the liner plate 424, which is a partition surface between the heat exchange passage 415 and the low temperature plenum 405, respectively, in a horizontal cross section (a cross section along a straight line in the horizontal direction in the drawing).
It forms a circle concentric with the furnace wall 403A of No. 03. That is, the heat exchange flow passage 415 forms an annular space sandwiched between the liner plate 421 and the liner plate 424.

In the structure of the furnace wall cooling mechanism 410 described above, the cooling fluid is the high pressure plenum 4 as shown by → in the figure.
16 flows into the ascending flow path 411 and is caused to flow upward along the furnace wall 403A by the ascending flow path 411.
1 overflows the liner plate 421 from the vicinity of the upper end of the downward flow path 4
It flows into 12. Further, the cooling fluid flowed downward by the descending passage 412 flows into the heat exchange passage 415 from the lower end of the descending passage 412, and is filled in the low temperature plenum 405 via the liner plate 424 in the heat exchanging passage 415. After exchanging heat with the fluid, the fluid in the low temperature plenum 5 is cooled and cooled, and then discharged to the low temperature plenum 405.

Further, the structure other than the reactor wall cooling mechanism 410 in the fast breeder reactor of this embodiment, for example, the structure such as the core, the high temperature plenum, the intermediate plenum, etc., is a retaining layer connected to the intermediate plenum 404 inside the descending flow passage 412. Except that 413 is provided, it is almost the same as the first to third embodiments.

Next, the operation of this embodiment will be described with reference to FIG. As a comparative example of this embodiment, FIG. 8 shows a furnace wall cooling mechanism 910 of a fast breeder reactor in the prior art. The parts common to the present embodiment shown in FIG. 7 are shown by associating the numbers in the 400s with the numbers in the 900s. In FIG. 8, the difference from the furnace wall cooling mechanism 410 of the present embodiment shown in FIG. 7 is that the cooling fluid flowing into the descending flow passage 912 through the ascending flow passage 911 is at a low temperature immediately below the lower end of the descending flow passage 912. Plenum 90
It is to be discharged to 5. Structure Thus, the difference T-T _L between the temperature T _L of the low-temperature fluid temperature T and cold plenum of fluid discharged becomes near 100K, the vicinity of the discharge portion that can withstand the thermal fatigue due to the temperature difference A material must be used, which is not preferable in terms of strength and cost.

However, in the furnace wall cooling mechanism 410 of this embodiment shown in FIG. 7, the cooling fluid is the low temperature plenum 4.
Heat exchange flow path 4 provided at the outlet portion discharged to 05
By exchanging heat between the cooling fluid and the fluid in the low temperature plenum 405 at 15, the cooling fluid is preliminarily exchanged in the heat exchange passage 415.
Therefore, the cooling fluid temperature T and the low-temperature plenum fluid temperature T _L are lower than those in the case of being discharged from the conventional furnace wall cooling mechanism 910 (see FIG. 8) having no heat exchange flow path.
It is possible to reduce the difference T- _TL with the difference.

That is, in the reactor wall cooling mechanism 410 of the fast breeder reactor of this embodiment, the inner diameter of the heat exchange passage 415 (the distance of the liner 424 from the axis of the reactor vessel 403) is set to 10.
m, the outer diameter (distance from the axis of the reactor vessel 403 of the liner plate 421) is 10.1 m (that is, the flow passage width is 0.05 m),
Between the fluid in the low temperature plenum 405 and the cooling fluid at the inlet of the heat exchange flow passage 415, the plate thickness of the constituent material of the heat exchange flow passage 415 is 5 mm, the flow rate of the cooling fluid flowing into the heat exchange flow passage 415 is 100 kg / s. The temperature difference of 100 K from the heat exchange passage 415 through the liner plate 424 to the low temperature plenum 40.
Estimating the heat transfer rate to 200 to 200 W / m ² K, the fluid temperature T _L in the low temperature plenum 405 and the heat exchange flow path 4 when the vertical length of the heat exchange flow path 415 is changed.
15 The change in the difference T− _TL with the cooling fluid temperature T at the outlet is
It shows almost the same tendency as the change of T _H -T in the first embodiment shown in FIG. 4, and for example, when the vertical length of the heat exchange channel 415 is 2 m, (T-T _L ) / (To-
T _L ) ≈0.35, and the difference T−T _L between the temperature T of the discharged cooling fluid and the temperature T _L of the fluid in the low temperature plenum 405 is the temperature difference To−T when the heat exchange flow passage 415 is not provided. About 35 of _L
% Can be reduced. That is, according to this embodiment, the same effect as that of the first embodiment can be obtained.

A fifth embodiment of the present invention will be described with reference to FIG. This example is an example of a fast breeder reactor having different furnace wall cooling mechanisms. The furnace wall cooling mechanism of the fast breeder reactor of this embodiment is shown in FIG. Parts common to the first embodiment are designated by common numbers. In FIG. 9, the furnace wall cooling mechanism 510 according to the present embodiment is the furnace wall cooling mechanism 410 according to the fourth embodiment.
The difference is that the liner plate 524 of the heat exchange channel 515 provided below the descending channel 412 is not provided in parallel with the liner plate 421 which is a partition plate for the ascending channel 411 and the descending channel 412. Horizontal direction (right and left direction in the figure)
That is, the heat exchange flow passage 515 is provided in the low temperature plenum 405 to cool the cooling fluid flowing from the descending flow passage 412.
It is a horizontal flow path leading to. Other points are the same as the furnace wall cooling mechanism 410 of the fourth embodiment.

In the above, as in the fourth embodiment, the heat exchange flow passage 515 has a flow passage width of 0.05 m and a heat exchange flow passage 515.
The thickness of the component material of 5 mm, the flow rate of the cooling fluid flowing into the heat exchange passage 515 is 100 kg / s, and the low temperature plenum 405.
The temperature difference between the fluid inside and the cooling fluid at the inlet of the heat exchange flow passage 515 is 100 K, and the heat transfer rate from the heat exchange flow passage 515 to the low temperature plenum 405 via the liner plate 524 is 200 W / m ² K. It is estimated that the low-temperature plenum 4 when the horizontal length of the heat exchange channel 515 is changed.
Change in the difference T-T _L of 05 in the fluid temperature T _L and the cooling fluid temperature T of the heat exchange passage 515 outlet portion is substantially the same as the change in T _H -T in the first embodiment shown in FIG. 4 Show trends,
For example, when the horizontal length of the heat exchange flow path 515 is 2 m, (T− _TL ) / (To− _TL ) ≈0.35, and the temperature T of the discharged cooling fluid and the low temperature plenum 405.
The difference T-T _L between the temperature T _L of the fluid of the inner can be reduced to the order of about 35% of the temperature difference the To-T _L in the absence of heat exchange passage 515. That is, according to this embodiment, the same effect as that of the first embodiment can be obtained.

[0046]

According to the present invention, heat exchange between the cooling fluid and the fluid in the high temperature / low temperature plenum is performed by the heat exchange flow passage provided at the outlet of the reactor vessel cooling mechanism where the cooling fluid is discharged. Therefore, the temperature difference between the cooling fluid and the fluid in the high-temperature / low-temperature plenum can be reduced as compared with the case where the cooling fluid is discharged from the conventional reactor vessel cooling mechanism having no heat exchange passage. Therefore, the strength condition of the structural material used near the outlet portion is relaxed, and even when the same structural material as the conventional one is used, the strength is improved and the life is extended, so that the cost can be reduced.

Further, according to the present invention, heat exchange between the cooling fluid and the fluid in the high temperature plenum is performed in the heat exchange passage provided at the outlet of the reactor vessel cooling mechanism where the cooling fluid is discharged. Cooling fluid temperature T, which was close to 150 K when discharged from the reactor vessel cooling mechanism with no heat exchange flow path
It is possible to reduce the difference T _H -T the hot plenum fluid temperature T _H and. Therefore, the strength condition of the structural material used near the outlet is relaxed, and even when the same structural material as the conventional one is used, the strength is improved and the life is extended.
The cost can be reduced.

Further, according to the present invention, heat exchange between the cooling fluid and the fluid in the low temperature plenum is performed in the heat exchange passage provided at the outlet of the reactor vessel cooling mechanism where the cooling fluid is discharged. it is possible to reduce the difference T-T _L between the cooling fluid temperature T and the low temperature plenum fluid temperature T _L that was near 100K when discharged from the inner reactor vessel cooling mechanism of the heat exchange passage. Therefore, the strength condition of the structural material used near the outlet portion is relaxed, and even when the same structural material as the conventional one is used, the strength is improved and the life is extended, so that the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a structural diagram of a furnace wall cooling mechanism of a fast breeder reactor according to a first embodiment of the present invention.

FIG. 2 is a structural diagram of a fast breeder reactor.

FIG. 3 is a structural diagram of a furnace wall cooling mechanism of a fast breeder reactor in the related art.

FIG. 4 is a diagram showing changes in the difference between the cooling fluid temperature at the heat exchange passage outlet and the fluid temperature in the high temperature plenum.

FIG. 5 is a structural diagram of a furnace wall cooling mechanism of a fast breeder reactor according to a second embodiment of the present invention.

FIG. 6 is a structural diagram of a furnace wall cooling mechanism of a fast breeder reactor according to a third embodiment of the present invention.

FIG. 7 is a structural diagram of a furnace wall cooling mechanism of a fast breeder reactor according to a fourth embodiment of the present invention.

FIG. 8 is a structural diagram of a furnace wall cooling mechanism of a fast breeder reactor in the related art.

[Explanation of symbols]

 1 Core 3 Reactor Vessel 3A Reactor Wall 4 Intermediate Plenum 5 Low Temperature Plenum 6 High Temperature Plenum 9 Piping 10 Reactor Wall Cooling Mechanism (Reactor Vessel Cooling Mechanism) 11 Ascending Flow Path (First Ascending Flow Path) 12 Downflow Flow Path 13 Intermediate Flow path 15 Heat exchange flow path 16 High pressure plenum 22 Liner surface (third partition surface) 23 Liner surface (first partition surface) 24 Liner surface (second partition surface) 210 Reactor wall cooling mechanism (reactor vessel cooling Mechanism) 213 Ascending flow path (second rising flow path) 215 Heat exchange flow path 224 Liner surface (fourth partition surface) 224a Discharge port 310 Reactor wall cooling mechanism (reactor vessel cooling mechanism) 315 Heat exchange flow path 315a To c pipe 403A furnace wall 405 low temperature plenum 406 high temperature plenum 410 furnace wall cooling mechanism (reactor vessel cooling mechanism) 411 ascending flow path 412 descending flow path (first descending flow path) 415 heat Exchange channel (second descending channel) 416 High-pressure plenum 421 Liner surface (fifth partition surface) 424 Liner surface (sixth partition surface) 510 Reactor wall cooling mechanism (reactor vessel cooling mechanism) 515 Heat exchange flow Road

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[Procedure amendment]

[Submission date] May 23, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a structural diagram of a furnace wall cooling mechanism of a fast breeder reactor according to a first embodiment of the present invention.

FIG. 2 is a structural diagram of a fast breeder reactor.

FIG. 3 is a structural diagram of a furnace wall cooling mechanism of a fast breeder reactor in the related art.

FIG. 4 is a diagram showing changes in the difference between the cooling fluid temperature at the heat exchange passage outlet and the fluid temperature in the high temperature plenum.

FIG. 5 is a structural diagram of a furnace wall cooling mechanism of a fast breeder reactor according to a second embodiment of the present invention.

FIG. 6 is a structural diagram of a furnace wall cooling mechanism of a fast breeder reactor according to a third embodiment of the present invention.

FIG. 7 is a structural diagram of a furnace wall cooling mechanism of a fast breeder reactor according to a fourth embodiment of the present invention.

FIG. 8 is a structural diagram of a furnace wall cooling mechanism of a fast breeder reactor in the related art.

FIG. 9 is a structural diagram of a furnace wall cooling mechanism of a fast breeder reactor according to a fifth embodiment of the present invention.

[Explanation of Codes] 1 core 3 reactor vessel 3A reactor wall 4 intermediate plenum 5 low temperature plenum 6 high temperature plenum 9 piping 10 reactor wall cooling mechanism (reactor vessel cooling mechanism) 11 ascending channel (first ascending channel) 12 Downward flow path 13 Intermediate flow path 15 Heat exchange flow path 16 High pressure plenum 22 Liner surface (third partition surface) 23 Liner surface (first partition surface) 24 Liner surface (second partition surface) 210 Furnace wall cooling mechanism (Reactor vessel cooling mechanism) 213 Ascending channel (second ascending channel) 215 Heat exchange channel 224 Liner surface (fourth partition surface) 224a Discharge port 310 Reactor wall cooling mechanism (reactor vessel cooling mechanism) 315 Heat exchange flow passage 315a-c Pipe 403A Furnace wall 405 Low temperature plenum 406 High temperature plenum 410 Reactor wall cooling mechanism (reactor vessel cooling mechanism) 411 Upward flow passage 412 Downward flow passage (first descending flow) Passage 415 heat exchange passage (second descending passage) 416 high-pressure plenum 421 liner surface (fifth partition surface) 424 liner surface (sixth partition surface) 510 reactor wall cooling mechanism (reactor vessel cooling mechanism) 515 heat exchange channel

Claims (11)

[Claims] 1. A reactor vessel filled with a primary system coolant, a reactor core disposed inside the reactor vessel, a low temperature plenum provided at a lower portion of the reactor vessel, and a reactor vessel of the reactor vessel. A high temperature plenum provided in an upper part, a high pressure plenum provided in a lower part of the reactor vessel and connected to a pipe for introducing the primary coolant from the outside of the reactor into the low temperature plenum, and an inside of a reactor wall of the reactor vessel A fast breeder reactor having a reactor vessel cooling mechanism which is installed in the high pressure plenum to guide the cooling fluid to cool the reactor wall and discharge the cooling fluid to one of the high temperature plenum and the low temperature plenum. The container cooling mechanism is configured such that at the outlet portion where the cooling fluid is discharged to one of the high temperature plenum and the low temperature plenum, the cooling fluid and one of the high temperature plenum and the low temperature plenum Fast breeder reactor characterized by having a heat exchange passage for heat exchange with the filled fluid. 2. A reactor vessel filled with a primary coolant, a reactor core arranged inside the reactor vessel, a low temperature plenum provided at a lower portion of the reactor vessel, and a reactor vessel of the reactor vessel. A high temperature plenum provided in an upper part, a high pressure plenum provided in a lower part of the reactor vessel and connected to a pipe for introducing the primary coolant from the outside of the reactor into the low temperature plenum, and an inside of a reactor wall of the reactor vessel In a fast breeder reactor having a reactor vessel cooling mechanism which is provided on a side surface and which guides a cooling fluid from the high-pressure plenum through the low-temperature plenum to cool the furnace wall and discharge the cooling fluid to the high-temperature plenum, The furnace vessel cooling mechanism is a heat exchange flow for exchanging heat between the cooling fluid and the fluid filled in the high temperature plenum at an outlet portion where the cooling fluid is discharged to the high temperature plenum. Fast breeder reactor characterized by having a. 3. A reactor vessel filled with a primary coolant, a reactor core arranged inside the reactor vessel, a low temperature plenum provided in the lower portion of the reactor vessel, and a reactor vessel of the reactor vessel. A high temperature plenum provided in an upper part, a high pressure plenum provided in a lower part of the reactor vessel and connected to a pipe for introducing the primary coolant from the outside of the reactor into the low temperature plenum, and an inside of a reactor wall of the reactor vessel A fast breeder reactor having a reactor vessel cooling mechanism which is provided on a bottom surface and an inner side surface, introduces a cooling fluid from the high pressure plenum, cools the reactor wall, and discharges the cooling fluid to the low temperature plenum, The cooling mechanism has a heat exchange passage for exchanging heat between the cooling fluid and the fluid filled in the low temperature plenum at an outlet portion where the cooling fluid is discharged to the low temperature plenum. Fast breeder reactor, wherein the door. 4. The fast breeder reactor according to claim 1 or 2, wherein the reactor vessel cooling mechanism is provided closest to a reactor wall in the reactor vessel, and the cooling fluid flowing from the low temperature plenum is supplied to the reactor vessel. An ascending flow path that flows upward along the wall, a descending flow path that is provided inside the ascending flow path and that causes the cooling fluid that flows from near the upper end of the ascending flow path to flow downward, and an inside of the descending flow path. There is an intermediate flow path that guides the cooling fluid that has flowed in from near the lower end of the descending flow path to an intermediate plenum provided between the low temperature plenum and the high temperature plenum, and the heat exchange flow path, A fast breeder reactor, which is provided inside the intermediate flow path above the intermediate plenum and is an ascending flow path for guiding the cooling fluid flowing from the intermediate plenum to the high temperature plenum. 5. The fast breeder reactor according to claim 1 or 2, wherein the reactor vessel cooling mechanism is provided on the most reactor wall side in the reactor vessel, and the cooling fluid flowing from the low temperature plenum is supplied to the reactor vessel. A first ascending flow path that flows upward along the wall, and a descending flow path that is provided inside the first ascending flow path and that causes the cooling fluid that has flowed in from near the upper end of the first ascending flow path to flow downward. And a second ascending flow path that is provided inside the descending flow path and that causes the cooling fluid that has flowed in from near the lower end of the descending flow path to flow upward. And a discharge port provided on a partition surface of the high temperature plenum. 6. The fast breeder reactor according to claim 1 or 2, wherein the reactor vessel cooling mechanism is provided on the most reactor wall side in the reactor vessel, and cools the cooling fluid flowing from the low temperature plenum to the reactor. An ascending flow path that flows upward along the wall, a descending flow path that is provided inside the ascending flow path and that causes the cooling fluid that flows from near the upper end of the ascending flow path to flow downward, and an inside of the descending flow path. There is an intermediate flow path that guides the cooling fluid that has flowed in from near the lower end of the descending flow path to an intermediate plenum provided between the low temperature plenum and the high temperature plenum, and the heat exchange flow path, A fast breeder reactor having a lower end near the upper surface of the intermediate plenum and an upper end having at least one conduit projecting into the high temperature plenum. 7. The fast breeder reactor according to claim 1 or 3, wherein the reactor vessel cooling mechanism is provided on the most reactor wall side in the reactor vessel, and the cooling fluid flowing from the high pressure plenum is supplied to the reactor vessel. An ascending flow path that flows upward along the wall, and a first descending flow path that is provided inside the ascending flow path and that causes the cooling fluid that has flowed in from near the upper end of the ascending flow path to flow downward, and The heat exchange passage is provided inside the ascending passage below the first descending passage, and is a second descending passage that guides the cooling fluid flowing from the first descending passage to the low temperature plenum. Is a fast breeder reactor. 8. The fast breeder reactor according to claim 1 or 3, wherein the reactor vessel cooling mechanism is provided on the most reactor wall side in the reactor vessel, and cools the cooling fluid flowing from the high pressure plenum. An ascending flow path that flows upward along the furnace wall, and a descending flow path that is provided inside the ascending flow path and that causes the cooling fluid that has flowed in from near the upper end of the ascending flow path to flow downward, and that The exchange flow passage is a horizontal flow passage that is provided inside the ascending flow passage below the descending flow passage and guides the cooling fluid flowing from the descending flow passage to the low temperature plenum. Furnace. 9. The fast breeder reactor according to claim 4, wherein a first partition surface between the intermediate flow path and the heat exchange flow path, and a second partition surface between the heat exchange flow path and the high temperature plenum. Is a circle concentric with the reactor wall of the reactor vessel in a horizontal cross section, and the heat exchange passage forms an annular space sandwiched between the first partition surface and the second partition surface. Characteristic fast breeder reactor. 10. The fast breeder reactor according to claim 5,
The third partition surface between the descending flow path and the heat exchange flow path and the fourth partition surface between the heat exchange flow path and the high temperature plenum are concentric with the reactor wall of the reactor vessel in a horizontal cross section. And has a third partition surface and a fourth partition surface.
A fast breeder reactor characterized by forming an annular space sandwiched between the partition surface and the partition surface. 11. The fast breeder reactor according to claim 7,
The fifth partition surface of the ascending flow path and the descending flow path and the sixth partition surface of the heat exchange flow path and the low temperature plenum are concentric with the reactor wall of the reactor vessel in a horizontal cross section. A fast breeder reactor characterized by forming a circle, and the heat exchange flow path forming an annular space sandwiched between a fifth partition surface and a sixth partition surface.