JPH05281387A - Integrated fast neutron reactor circulating liquid metal through at least one ejector pump - Google Patents

Abstract

PURPOSE: To reduce the manufacturing cost of a reactor by increasing the capacity thereby reducing the size and/or the number of pump means. CONSTITUTION: The integrated fast neutron reactor employs 1 to 3 ejector pumps 22 in place of an ordinary mechanical pump. Each pump comprises a low capacity mechanical pump 42 for delivering a liquid metal vertically downward through a delivery nozzle 44 which ejects the liquid metal to the neck part of a secondary nozzle 46 coupled with a bearing part 24 through a supply pipe 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated fast neutron reactor in which at least one ejector pump device circulates a liquid metal between a core and a heat exchanger.

[0002]

BACKGROUND OF THE INVENTION In an integrated fast neutron reactor, all primary circuits of the reactor are located in a vertical, generally known as main vessel, sealed by a horizontal hermetic slab. Accordingly, the core or heat exchanger, or pump means used to circulate the liquid metal contained in the vessel between the core and the heat exchanger, is located in the vessel. The liquid metal filling the main vessel is covered by a neutral gas layer, which is generally composed of argon.

The core is actually located in the center of the main vessel and the heat exchangers and pumping means are annularly and alternatingly arranged around this core. And, generally, the pump means is constituted by a mechanical pump having an impeller, and the impeller is driven by an electric motor arranged above the sealing plate via a vertical long axis.

[0004]

By the way, in a high-power fast neutron reactor (for example, 2500 MWe),
Nominal flow rate required to cool the core (eg 18000
In order to ensure (kg / s), at least three mechanical pumps of this kind are required so that they are regularly distributed about the vertical axis of the main vessel. Moreover, these pumps are huge, with a maximum diameter close to 2 meters.

On the other hand, one of the problems that cannot be avoided in the industrialization of fast neutron reactors is the problem of manufacturing cost. In order to reduce the manufacturing cost, it is necessary to improve the size of the nuclear reactor, especially to reduce the diameter of the main vessel. However, it is unavoidable to use at least three large-diameter pumps in the conventionally known liquid metal pump means in the reactor main vessel, and as a result, a high-power reactor is required. In that case, the diameter reduction of the reactor main vessel had to be prevented.

[0006]

SUMMARY OF THE INVENTION The present invention comprises a novel pump means capable of reducing the number of parts required and / or reducing its overall size as compared to currently used mechanical pumps. The present invention relates to an integrated fast neutron reactor for the purpose of significantly reducing the size of a nuclear reactor and consequently reducing its manufacturing cost.

According to the present invention, in a vertical main vessel containing a liquid metal, a core, at least one heat exchanger,
To obtain such a result by means of an integrated fast neutron nuclear reactor comprising pump means capable of circulating liquid metal between the core and the heat exchanger, the pump means comprising at least one ejector pump device. You can

[0008]

In a high power reactor, whether a single ejector pump device having a flow rate necessary for cooling the core itself is used, or two ejector pump devices having a medium flow rate are used, Alternatively, depending on whether three ejector pump devices with low flow rates are used, it becomes possible to use an ejector pump device instead of a general mechanical pump. In the first case, the maximum diameter of the single ejector pump device is about half the maximum diameter of each of the three mechanical pumps used to deliver the same flow rate, and three 4 times less when using the ejector pump device. As a result, the overall size can be reduced in all cases, and it is possible to promote the above-described miniaturization and reduce the manufacturing cost of the nuclear reactor.

More specifically, the ejector pump device has a mechanical pump each having a discharge nozzle, and this discharge nozzle ejects to a secondary nozzle connected to the core via a supply pump. The mechanical pump supplies a relatively low flow rate, which is increased by a factor of 3 or more by the ejector formed by the combination of the discharge nozzle and the secondary nozzle.

In practicing the present invention, the discharge nozzle and the secondary nozzle are preferably arranged along a substantially vertical axis, and the secondary nozzle is preferably arranged below the discharge nozzle.

Further, in general, it is preferable that the core is arranged on a supporting portion which supports the core and supplies the liquid metal. Here, the supply pipe connecting the secondary nozzle to the core is jetted into the bearing.

Further, in a fast neutron reactor, in general, the inner vessel has a relatively high temperature collecting section flowing out of the core and a relatively low temperature collecting section flowing out of the heat exchanger inside the main vessel. To divide. Then, the ejector pump device is arranged in the collecting section having a relatively low temperature.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing an integrated fast neutron reactor cooled by a liquid metal according to the present invention.

FIG. 2 is an enlarged vertical sectional view of an ejector pump device according to the present invention which circulates the liquid metal in the main vessel of the nuclear reactor shown in FIG.

The liquid metal cooled integrated fast neutron reactor shown in FIG. 1 has a generally known structure. Therefore, only for the structural features necessary for understanding the present invention,
Described below.

This fast neutron reactor is provided with a vertical main vessel 10 whose upper end is sealed by a sealed slab 12. The main container 10 has a double exterior with a safety container 14, and is installed inside a container pit formed in a concrete caisson 16.

In an integrated reactor, generally, the main vessel 10 of the reactor contains a core 18, a heat exchanger 20, and pump means. According to the invention, this pump means is It comprises at least one ejector pump device 22. The core 18 is arranged on the vertical axis in the center of the main vessel 10 and has a support 2 for supplying liquid metal to the bottom thereof.
4 and a support structure 26 known as a floorboard. The heat exchanger 20 and the ejector pump device 22 are suspended around the sealed slab 12 and arranged around the core 18 of the main vessel 10.

The main vessel 10 is filled with a liquid metal, usually sodium, and contains a core 18 and a heat exchanger 2.
0, and the ejector pump device 22 is immersed in this liquid metal. This liquid metal is covered by a neutral gas layer 8 usually consisting of argon.

The inside of the main container 10 is divided by an inner container 30 into a collecting part 32 which has a relatively high temperature and a collecting part 34 which has a relatively low temperature. The bottom of the inner container 30 is joined to the peripheral portion of the support portion 24, and the relatively high temperature collecting portion 32 is formed between the inner container 30 and the main container 10.

As shown in FIG. 1, the heat exchanger 20 is arranged so as to penetrate through the inner container 30, and has an inlet 36 facing the relatively high temperature collecting section 32 and the relatively low temperature collecting section 36. And a discharge port 38 facing the inside of the portion 34.
Further, the ejector pump device 22 is arranged in the relatively low temperature collecting part 34 and is connected to the supplying support part 24 through the supply pipe 40.

By adopting such an arrangement, the liquid metal can be circulated between the core 18 and the heat exchanger 20 by using the ejector pump device 22 as shown by the arrow in FIG. More specifically, the relatively low temperature liquid metal in the collector 34 is sucked into the ejector pump device 22 and discharged into the core 18 via the supply pipe 40 and the bearing 24. As a result of the fission reaction in the core 18, the liquid metal is heated before it reaches the collector 32. Then, the liquid metal having a relatively high temperature passes through the heat exchanger 20 and transfers a part of the heat to the heat transfer fluid flowing through the secondary circulation path (not shown) of the nuclear reactor.
Therefore, the liquid metal has a low temperature when it passes through the heat exchanger 20 and reaches the collecting portion 34 from the discharge port 38.

FIG. 2 shows in detail the characteristic construction of the ejector pump device 22 according to the present invention. As shown therein, each ejector pump device 22 includes a mechanical pump 42 having a relatively low flow rate and an ejector formed by a discharge nozzle 44 and a secondary nozzle 46. Nozzle 46 is centered about the same vertical axis. More specifically, the liquid metal is discharged from the lower end of the mechanical pump 42 through the discharge nozzle 44, and further flows into the secondary nozzle 46 located below the mechanical pump 42.

The low-flow mechanical pump 42 is the same as the high-flow mechanical pump conventionally used in a fast neutron reactor, and the sealed slab 1 of the main vessel 10 of the reactor.
It is hung on the No. 2 and has an impeller (not shown). The impeller is rotated by an electric motor 48 (FIG. 1) located on the sealing slab 12 via a vertical drive shaft, also not shown.

The mechanical pump 42 corresponds to the inner container 3
It is installed in a vertical tubular shaft 50 whose lower end is joined to 0, the upper end of which is above the maximum level of the liquid metal in the relatively hot collecting part 32. It is arranged to be located in. Further, the lower end of the tubular shaft 50 is opened so that the mechanical pump 42 is arranged in the relatively low temperature collecting section 34.

The relatively low temperature liquid metal in the collecting section 34 is sucked by the mechanical pump 42 through the suction port 52 located in the cylindrical shaft 50 above the mechanical pump 42. The liquid metal is discharged by the mechanical pump 42 through the discharge nozzle 44 at the lower end thereof.
4 is arranged at substantially the same height as the inner container 30.
The discharge nozzle 44 faces vertically downward.
The secondary nozzle 46 having a diameter sufficiently larger than that of the secondary nozzle 46 is provided so as to face the neck portion and eject.

The discharge nozzle 4 is driven by the mechanical pump 42.
The liquid metal jetted through 4 forms an induction flow, and transfers its kinetic energy to the liquid metal in the relatively low temperature collecting section 34 located in the ejector pump device 22 section. , The guided flow of the ejector formed by the discharge nozzle 44 and the secondary nozzle 46. The guided flow is made to flow by the guided flow ejected from the discharge nozzle 44, and an induced flow larger than that induced by the mechanical pump 44 is produced at the outlet of the secondary nozzle 46.

As clearly shown by the arrow in FIG. 2, the liquid metal in the relatively low temperature collecting section 34 is dragged by the liquid metal ejected from the ejection nozzle 44, and the ejection nozzle 44 and the secondary nozzle. The secondary nozzle 46 is further passed through an annular space 54 formed between the secondary nozzle 46 and the second nozzle 46. And
The lower end of the secondary nozzle 46 communicates with the supply pipe 40 that is directly connected to the supply support portion 24.

The increase in the flow rate obtained by the coupling of the mechanical pump and the ejector is characterized in that it is three times or more the nominal flow rate of the mechanical pump. Due to this large increase in flow rate, a high-power fast neutron reactor (1500 MW)
For the cooling of the core of e), a single ejector pump device 22 whose maximum diameter is reduced to about half as compared with the mechanical pump conventionally used in such a reactor is used, or a smaller diameter of 2 or 3 is used. This can be done by using the ejector pump device of the machine.

While the overall size is reduced in this way, the internal structure of the reactor is simplified and the number of parts is reduced by using a single ejector pump device.
As a result, the manufacturing cost of the nuclear reactor can be reduced.

Further, by using the two ejector pump devices, it is possible to further reduce the manufacturing cost,
The overall size of the nuclear reactor can be further reduced, and at the same time, the structure can be simplified in the reduced size.

Further, by using the three ejector pump devices, it is possible to promote the securing of a more remarkable space while guaranteeing the required reduction of the manufacturing cost.

Further, in all cases, by using the ejector pump device according to the present invention, even if the mechanical pump 42 is stopped, good core cooling is performed by natural convection. The fact that it can be done is remarkable.

The following table shows the main characteristics of the ejector pump device 22 according to the present invention.
2 shows the case where three or three machines are used. However, these characteristics are such that the nominal flow rate of liquid metal in the core is about 18000 kg / s and the pressure gradient is about 5 ba.
It is obtained when r is set.

[0035]

[Table 1]

[0036]

As described above, the flow rate can be increased to reduce the size and / or the number of the pump means.
As a result, the manufacturing cost of the nuclear reactor can be reduced.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a liquid metal cooling type integrated fast neutron reactor according to the present invention.

FIG. 2 is an enlarged vertical sectional view of an ejector pump device that circulates liquid metal in the main vessel of the nuclear reactor shown in FIG.

[Explanation of symbols]

 10 Main Vessel 18 Core 20 Heat Exchanger 22 Ejector Pump Device 30 Internal Vessel 32 High Temperature Collection Section 34 Low Temperature Collection Section 40 Supply Pipe 42 Mechanical Pump 44 Discharge Nozzle 46 Secondary Nozzle

Claims (6)

[Claims] 1. A vertical main container for containing liquid metal,
A high speed comprising a core, at least one heat exchanger, and pump means capable of circulating the liquid metal between the core and the heat exchanger, the pump means comprising at least one ejector pump device. Neutron reactor. 2. The ejector pump device comprises a mechanical pump having a discharge nozzle, and the discharge nozzle comprises:
The nuclear reactor according to claim 1, which jets out to a secondary nozzle connected to the core by a supply pipe. 3. The nuclear reactor according to claim 2, wherein the discharge nozzle and the secondary nozzle are arranged substantially along a vertical axis, and the secondary nozzle is arranged below the discharge nozzle. 4. The core is arranged on a support for supplying liquid metal to the core, and a supply pipe connecting the secondary nozzle to the core is jetted to the support. Nuclear reactor. 5. The nuclear reactor according to claim 1, comprising one to three ejector pump devices. 6. The reactor comprises a main part of the main vessel, a relatively high temperature collecting part flowing out from the core, the ejector pump device, and a relatively high temperature collecting part flowing out from the heat exchanger. The nuclear reactor according to claim 1, further comprising an inner container that is divided into a low temperature collecting section.