JPH10332883A - Primary coolant circulation device of fast reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure minimum flow rate of coolant necessary for cooling core even in loss of main power and improve reliability by constituting so as to utilize heat stored in coolant and operate circulation pump by making power generated with a thermoelectric power generation system as a power source. SOLUTION: A primary coolant circulation device is provided with a plurality of circulation pump and includes a circulation pump 3 operated with the power generated with a thermoelectric power system 8 by utilizing the heat stored in the coolant 4 as a power source. The thermoelectric system 8 is constituted of a thermoelectric conversion module, heat pipe 2 for collecting heat as a high temperature side heat conduction means and a heat pipe 7 for radiating heat as a low temperature side heat conduction means. The thermoelectric conversion module is an assembly of a multitude of thermoelectric conversion unit and each thermoelectric conversion unit is constituted by contacting a high temperature side thermal stress mitigation pad and a low temperature side thermal stress mitigation pad on both sides of a thermoelectric conversion element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a primary coolant circulating apparatus for circulating a coolant in a primary cooling system of a fast reactor.
More specifically, the present invention relates to a primary coolant circulation device of a fast reactor that circulates coolant even when main power is lost due to a power failure or the like.

[0002]

2. Description of the Related Art A primary coolant circulation device for a fast reactor must ensure a minimum flow rate of coolant necessary to maintain the integrity of the core even if the main power is lost due to a power failure or the like. . For this reason, in the conventional primary coolant circulating device of a fast reactor, a flywheel and a pony motor are installed in a mechanical pump that circulates a coolant in a primary cooling system. That is, the pump is kept driven for a certain period of time by the rotational inertia of the flywheel even after the main power supply is lost, and the diesel generator is started or the electric power is started in a short time (about several tens of seconds) until the inertial energy is lost. The power source is switched to an emergency battery, and the power is used to operate the pony motor to maintain the rotation of the pump, thereby ensuring a coolant flow rate of about 10% of the rated flow rate.

[0003] Diesel generators that are started up by the loss of the main power supply are designed to be able to start up reliably in a short time. The emergency battery serving as the power supply for the pony motor is designed so that the pony motor can be continuously operated for a required time. And, in a real fast reactor plant, the combination of these is designed to provide multiplicity to further enhance the safety of the plant.

[0004]

However, in a fast reactor plant, it is particularly important to maintain the reliability of the equipment. For this purpose, a great deal of maintenance is required for the maintenance of diesel generators, emergency batteries, pony motors and the like. Effort is required. Further, from the viewpoint of reducing the amount of the plant and economical efficiency, it is desirable to eliminate the need for a diesel generator or an emergency battery. For these reasons, there is a demand for the development of a primary coolant circulation device for a fast reactor that is more reliable and easy to maintain.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a primary coolant circulating device for a fast reactor having a simple structure and high reliability.

[0006]

In order to achieve the above object, a primary coolant circulation device for a fast reactor according to claim 1 is provided.
In the primary coolant circulation device of a fast reactor having a plurality of circulation pumps, the circulation pump is operated by using power generated by a thermoelectric power generation system as a power source by utilizing heat stored in a coolant as the circulation pump. It is a configuration including.

Therefore, as long as heat is stored in the coolant, the thermoelectric power generation system generates power and continues to drive the circulation pump for circulating the coolant. That is, even if the main power is lost due to a power failure or the like, if the temperature of the core is high enough to circulate the primary coolant, power is generated using the heat, and the circulating pump removes the primary coolant. Circulation keeps the core cool.

In this case, it is preferable that the circulation pump is a DC motor driven pump operated by a DC current generated by the thermoelectric power generation system, as in the primary cooling and circulating device of the fast reactor according to the second aspect of the present invention. In this case, the DC motor drive pump, which is a circulation pump, can be directly driven by the DC current generated by the thermoelectric power generation system.

According to a third aspect of the present invention, the circulating pump is operated by an AC current obtained by converting a DC current generated by a thermoelectric power generation system by a DC / AC converter. Alternatively, an AC motor driven pump is preferable. In this case, since an alternating current can be generated, an electromagnetic pump or an AC motor driven pump can also be used as the main circulation pump.

Further, in the primary cooling and circulating apparatus of the fast reactor according to the present invention, the thermoelectric power generation system includes a thermoelectric conversion element for generating electric power based on a temperature difference between both surfaces, and a thermoelectric conversion element stored in a coolant on one side surface of the thermoelectric conversion element. High-temperature side heat conduction means to guide the heat, low-temperature side heat conduction means to cool the other side of the thermoelectric conversion element,
The high-temperature-side heat conduction means and the low-temperature-side heat conduction means are configured to be joined to the thermoelectric conversion element with a thermal stress relaxation pad having a functionally graded material interposed therebetween.

Therefore, a temperature difference occurs between one side surface of the thermoelectric conversion element heated by the heat of the coolant guided by the high-temperature side heat conduction means and the other side surface cooled by the low-temperature side heat conduction means. . This temperature difference causes the thermoelectric conversion element to generate power and operate the circulation pump. Thermal stress is generated in the thermoelectric conversion element due to a temperature difference between both surfaces, and the thermal stress is absorbed by the functionally gradient material of each thermal stress relieving pad.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on the best mode shown in the drawings.

FIG. 1 shows an example of an embodiment of a primary coolant circulation device of a fast reactor to which the present invention is applied. This fast reactor
The coolant 4 of the primary cooling system for cooling the core 19 in the reactor vessel 15 is, for example, a tank-type fast breeder reactor using liquid sodium. The primary coolant circulation device includes a plurality of circulation pumps. The circulating pump includes a circulating pump 3 operated by using the power generated by the thermoelectric power generation system 8 using the heat stored in the coolant 4 as a power source. Here, when the circulating pump 3 uses the DC current generated by the thermoelectric power generation system 8 as it is, a DC motor drive pump is used.
When converting into AC through a converter, an electromagnetic pump or an AC motor drive pump is used.

As shown in FIG. 2, the thermoelectric power generation system 8 includes a thermoelectric conversion module 6, a heat collecting heat pipe 2 as a high-temperature side heat conducting means, and a heat radiating heat pipe 7 as a low temperature side heat conducting means. It is provided with. The thermoelectric conversion module 6 is a set of a large number of thermoelectric conversion units 9 as shown in FIG. 3, and each thermoelectric conversion unit 9 has a high-temperature side thermal stress on both side surfaces of the thermoelectric conversion element 1 as shown in FIG. It is configured by joining a relaxation pad 10 and a low-temperature-side thermal stress relaxation pad 11.

The thermoelectric conversion element 1 is an element that generates electric power by a temperature difference between both surfaces, and is, for example, a lead-tellurium (PbTe) semiconductor element. However, the present invention is not limited to this, and for example, a bismuth tellurium (BiTe) semiconductor element, a silicon germanium (SiGe) semiconductor element, or the like can be used. Which of these semiconductor elements to choose depends on
It is determined according to the operating temperature range and the like. Both elements are
It is composed of a P-type semiconductor having a high hole concentration and an N-type semiconductor having a high electron concentration, and an electromotive force is generated by a combination of both.
Actually, the output is increased by electrically connecting a plurality of pairs of P-type semiconductors and N-type semiconductors in series.

Each of the thermal stress relaxation pads 10 and 11 is composed of functionally graded materials 12 and 13 and a graphite layer 14. The graphite layer 14 of each of the thermal stress relaxation pads 10 and 11 is disposed between each of the functionally graded materials 12 and 13 and the thermoelectric conversion element 1 to prevent the components of the thermoelectric conversion element 1 from diffusing.

Each of the functionally graded materials 12 and 13 is obtained by gradually changing the composition ratio of the thermal stress relaxation material / thermal conductor and the electric insulating material in the thickness direction. A material having a large thermal conductivity and a small elastic constant, for example, a metal such as copper or palladium. Here, copper has a very small ratio (E / λ) of the elastic constant E to the thermal conductivity λ. Therefore, when copper is used as the thermal stress relaxation material and thermal conductor having thermal conductivity, thermal stress can be reduced while maintaining high thermal conductivity. However, high operating temperature S
When an iGe element or the like is used as the thermoelectric conversion element 1, since the operating temperature of the high-temperature-side thermal stress relaxation pad 10 approaches the melting point of copper, only the low-temperature-side thermal stress relaxation pad 11 is made of copper. For the thermal stress relaxation pad 10, it is preferable to use palladium, which has excellent performance, next to copper. However, it goes without saying that the material used as the thermal stress relaxation material and thermal conductor is not necessarily limited to copper or palladium. In this case, it is more preferable that the thermal conductivity is large and the elastic constant is small, that is, the ratio of the elastic constant to the thermal conductivity is small. The material is not necessarily limited to metal as long as it satisfies this property. On the other hand, the electrical insulating material is, for example, alumina, and ceramics such as silicon nitride and silicon carbide can be used in addition to alumina. Various ceramics such as silicon carbide are preferable materials because of their good thermal conductivity, little deformation by heat, and excellent electrical insulation. However, the material used as the electric insulating material is not necessarily limited to ceramics such as alumina and silicon nitride.
In each of the functionally gradient materials 12 and 13 of the present embodiment, the thermoelectric conversion element 1 side is formed of copper (Cu) layers (hereinafter, referred to as Cu layers) 12a and 13a which are both a thermal stress relaxation material and a thermal conductor.
The heat collecting heat pipe 2 or the heat radiating heat pipe 7 is made of alumina (Al ₂ O ₃ ) layers (hereinafter, referred to as alumina layers) 12b and 13b, which are electric insulating materials.
Layers 12c, 1 in which the composition ratio of copper and alumina is gradually changed between 2a, 13a and each of alumina layers 12b, 13b.
3c. Each of the Cu layers 12a and 13a also functions as an electrode that electrically connects the thermoelectric conversion elements 1P and 1N in series.

Copper (thermal stress relieving material and thermal conductor) and alumina (electric insulating material) constituting the functionally graded materials 12 and 13 of the thermal stress relieving pads 10 and 11 are all obtained in the form of powder. be able to. Therefore, the functionally gradient materials 12 and 13 can be manufactured by the powder metallurgy method.
For example, using a device that injects powder from two nozzles, copper powder is injected into the mold from one nozzle, and alumina powder is injected into the mold from the other nozzle. In this case, by controlling the injection ratio of both nozzles, a layered or plate-like pellet (a lump of powder) is produced in which the filling ratio of each powder is gradually changed from the inside in the thickness direction to both the outside. After compression molding of the pellets, the pellets are heated in a furnace and sintered to form the functionally graded materials 12 and 13.
Can be obtained.

The functionally graded material 1 manufactured in this manner
In Nos. 2 and 13, the composition ratio of the thermal stress relaxation material / thermal conductor and the insulating material, which have greatly different linear expansion coefficients, is gradually changed. Can disperse the thermal stress generated therein without concentrating it at a specific location.

The heat-collecting heat pipe 2 has a high-temperature-side thermal stress relaxation pad 10 on one side (high-temperature side) of each thermoelectric conversion element 1.
And guides the heat stored in the coolant 4 to the high-temperature side surface. Further, the heat radiating heat pipe 7 is joined to the other side surface (low temperature side surface) of each thermoelectric conversion element 1 with the low temperature side thermal stress relaxation pad 11 interposed therebetween, and cools the low temperature side surface.

Next, the operation of the primary coolant circulation device will be described.

The heat of the coolant 4 is transmitted to the high-temperature side of each thermoelectric conversion element 1 of the thermoelectric power generation system 8 by the heat collection heat pipe 2, and the heat of the low temperature side of each thermoelectric conversion element 1 is transferred to the heat radiation heat pipe 2. 7 removed. Therefore, a temperature difference occurs between both surfaces of each thermoelectric conversion element 1, and each thermoelectric conversion element 1 generates electric power for driving the circulation pump 3. That is, even when the main power is lost due to a power failure or the like, if the temperature of the core 19 is high enough to circulate the coolant 4, power is generated by using the heat, and the circulation pump 3 4 is continued to cool the core.

The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention. For example, in the above description, the present invention is applied to a tank type fast reactor, but the present invention is also applicable to a loop type or hybrid type fast reactor. However, when applied to a loop type reactor, the pump 3 driven by the power of the thermoelectric power generation system 8
Must be installed in the reactor vessel 15. Therefore, depending on the structure of the reactor vessel 15, some measures may be required to secure the installation space for such a pump.
For example, in the case of a "lower inflow type" loop type fast reactor in which the primary main pipe is connected to a lower portion of the reactor vessel 15, the diameter of the reactor vessel 15 needs to be slightly increased. On the other hand, a "top inflow type" in which the primary main pipe is connected to the side surface of the reactor vessel 15 or a "top entry type" loop type fast reactor in which the shielding plug 21 penetrates into the reactor vessel 15 from above. In such cases, installation of such a pump is relatively easy since a sufficient space is originally secured in the reactor vessel.

In the above description, the functionally graded material 1 of each of the thermal stress relaxation pads 10 and 11 sandwiching the thermoelectric conversion element 1 is described.
As for 2, 13, a composition in which the composition ratio of the thermal stress relieving material / thermal conductor and the electric insulating material is gradually changed from one side to the other side is used. You may make it change from the inside of a thickness direction to both outer sides, respectively. For example, as shown in FIG. 5, alumina (electric insulating material) layers 12b and 13b are formed at the center in the thickness direction of the respective functionally graded materials 12 and 13, and alumina and Cu (a thermal stress relaxation material / The layers 12c and 13c in which the composition ratio of the conductor is gradually changed may be formed, and the Cu layers 12a and 13a may be formed outside these layers. In this case, the direction of the change in the composition ratio is reversed in the middle as viewed from the entire thickness direction of the respective functionally graded materials 12 and 13, that is, the ratio between the electrical insulating material and the thermal stress relieving material / thermal conductor increases. It can be changed on the way whether it tends to decrease or decrease. That is, the respective functionally graded materials 12 and 13 are made of Cu (metal) on both sides of the alumina (ceramic) layers 12b and 13b.
With the structure in which the layers 12a and 13a are arranged, it is possible to prevent the occurrence of warpage and cracks due to the difference in thermal expansion between the metal and the ceramic in the process of cooling from the sintering temperature to room temperature during manufacturing. For this reason, the production of the respective functionally graded materials 12 and 13 is facilitated, and the cost can be reduced. In addition, soundness can be improved and a stable product can be obtained. In addition, since both outer sides of the respective functionally graded materials 12 and 13 can be made of metal (Cu) layers 12a and 13a, the materials on both outer sides of the respective functionally graded materials 12 and 13 can be used as the heat collecting heat pipe 2 or the heat radiating heat pipe 7 or a material having a similar coefficient of linear expansion, the high-temperature side thermal stress relaxation pad 10 and the heat collection heat pipe 2, and the low-temperature side thermal stress relaxation pad 11 and the heat radiation heat pipe 7 The joining is facilitated and the joining strength can be increased. Further, it is not always necessary to form the alumina layers 12b and 13b at the center of the outer Cu layers 12a and 13a, and the alumina layers 12b and 13b are formed at positions deviated toward one of the Cu layers 12a and 13a. May be. That is, the thicknesses of the layers 12c and 13c on both sides do not need to be the same, but may be changed. In addition, both layers 12c, 1
The ratio of the change of the composition ratio of 3c is not necessarily the thermoelectric element 1 side and the heat collecting heat pipe 2 or the heat radiating heat pipe 7.
Needless to say, it is not necessary to make the same on the side and it may be changed. The Cu layers 12a and 13a made of the above-described thermal stress relieving material and heat conductor and the alumina layers 12b and 13b made of an electric insulating material do not necessarily need to be made of 100% Cu or alumina. It may include an electric insulating material or the like as long as the function as the thermal stress relieving material and the heat conductor can be secured, or include the thermal stress relieving material and the heat conductor as long as the function as the electric insulating material can be substantially secured. But of course it is good.

Further, in the above description, the thermoelectric power generation system 8 includes the thermoelectric conversion element 1, the heat collection heat pipe 2 as the high-temperature side heat conduction means, and the heat radiation heat pipe 7 as the low-temperature side heat conduction means. The heat pipes 2 and 7 are joined to the thermoelectric conversion element 1 with the thermal stress relaxation pads 10 and 11 having the functionally graded materials 12 and 13 interposed therebetween. Of course, 11 may be omitted.

[0026]

【Example】

(Embodiment 1) [Configuration of primary coolant circulating device] As shown in FIGS. 6 and 7, a total of three main coolant pumps of the primary coolant circulating device are used.
A mechanical main circulating pump is installed, one of which is a circulating pump (hereinafter referred to as a DC motor driven pump) 3 operated by a DC current generated by the thermoelectric power generation system 8, and the remaining two are main pumps. A circulating pump (hereinafter referred to as an AC motor driven pump) 5 operated by an AC current from a power supply 18 was used. Although the conventional main circulation pump has a flywheel and a pony motor in case of a main power loss, the DC motor drive pump 3 according to the present embodiment omits both the flywheel and the pony motor, and As for the AC motor drive pump 5, only the pony motor was omitted. The two AC motor drive pumps 5 were set to share 90% (each 45%) of the primary cooling system rated flow, and the remaining 10% to the DC motor drive pump 3.

[Structure of Thermoelectric Power Generation System] Twenty-one thermoelectric conversion modules 6 of the thermoelectric conversion system 8 are housed side by side in a casing 20 shown in FIG.
Installed above. Each thermoelectric conversion module 6 was composed of 360 thermoelectric conversion units 9. The output per thermoelectric conversion unit 9 having a size of about 25 mm square is about 8 W,
One thermoelectric conversion module 6 has an output of about 2.88 kW. Therefore, this module 6 is about 60M with 21
The output of W is obtained. The size of the thermoelectric conversion module 6 is 30 cm in length and 13 cm in width.
By arranging seven rows and seven rows in the horizontal direction, 21 heat transfer conversion modules 6 could be installed in a square space of 1 m square on the reactor shield plug 21.

Six heat pipes 2 for heat collection are provided for each thermoelectric conversion module 6, and 126 heat pipes are provided for the entire thermoelectric power generation system 8. At this time, the heat collecting heat pipes 2 were arranged so as to be arranged in a rectangular shape with a predetermined gap therebetween. Further, the lower end of each heat collecting heat pipe 2 is passed through the shielding plug 21 so that the reactor vessel 1
5 was inserted into the hot plenum, and the upper end of each was joined to one side surface of each thermoelectric conversion element 1 with the high-temperature side thermal stress relaxation pad 10 of the thermoelectric conversion unit 9 interposed therebetween. Cesium was sealed in each heat collecting heat pipe 2 as a working fluid. However, lithium or the like may be sealed instead of cesium.

Seven heat pipes 7 for heat radiation are provided for each thermoelectric conversion module 6, and 147 heat pipes are provided for the thermoelectric power generation system 8 as a whole. At this time, the heat-radiating heat pipes 7 were arranged so as to be arranged in a substantially rectangular shape with a gap of a predetermined distance therebetween. Each of these heat-dissipating heat pipes 7 was housed in the inner passage of the double duct 16, and the lower end thereof was joined to the other side, that is, the low-temperature side of the corresponding thermoelectric conversion element 1. That is, each heat radiating heat pipe 7 was joined to the other side surface of each thermoelectric conversion element 1 with the low-temperature side thermal stress relaxation pad 11 of the thermoelectric conversion unit 9 interposed therebetween. As shown in FIG. 8, a heat radiating panel 17 was fixed near the upper end of each heat radiating heat pipe 7. Water was sealed as a working fluid sealed in each heat radiation pipe 7. However, it is needless to say that it is not limited to water.

The double duct 16 accommodating the heat-dissipating heat pipe 7 has its inner passage and outer passage communicated at the lower end, while its upper end is projected outside the reactor building to form the inner passage and the outer passage. Open to the atmosphere. Therefore, in the double duct 16, cold outside air descends in the outer passage, inverts at the lower end portion, flows into the inner passage, is heated while cooling the heat-dissipating heat pipe 7, and is raised and discharged. That is, each heat-radiating heat pipe 7 can remove heat by natural circulation of the outside air.

When applied to a small fast reactor having an electric output of about 60,000 kW, the heat energy transmitted to the thermoelectric conversion module 6 by the heat collecting heat pipe 2 is 750 kW. Then, assuming that the energy conversion efficiency of the thermoelectric conversion module 6 is 8%, the thermoelectric power generation system 8 generates 60 kW of power. The remaining 690 kW of heat energy is transmitted to the outside of the reactor containment vessel 15 by the heat radiating heat pipe 7 and released. In this case, the heat flux in the axial direction of the heat collecting heat pipe 2 is about 300 W / cm ² .
Therefore, 126 heat pipes having an inner diameter of 50 mm can be arranged in a 1 m square cross section space with a gap therebetween. Such a cross-sectional dimension is smaller than the diameter of each of the circulation pumps 3 and 5, and can be easily installed in the reactor vessel 15. The same applies to the heat pipe 2 for heat collection.

[Operating Conditions] The temperature of liquid sodium as the coolant 4 in the hot plenum of the reactor vessel in the normal operating state is about 530 ° C. This heat was guided to one side surface of each thermoelectric conversion element 1 by the heat collection heat pipe 2. The temperature of the atmosphere (outside air) in which the outside passage and the inside of the double duct 16 are open is about 30 ° C., and the heat at the other end surface of each thermoelectric conversion element 1 is transmitted through the heat-radiating heat pipe 7 and the double duct 16. Was discharged into the atmosphere. Therefore,
A temperature difference capable of generating power occurred between both surfaces of each thermoelectric conversion element 1.

[Operation] When the reactor is operating normally, the two AC motor driven pumps 5 are connected to the main power source (AC).
The DC motor drive pump 3 is driven by electric power supplied from the DC power supply 18 and is driven by a DC power supply supplied from the thermoelectric conversion element 1 of the thermoelectric power generation system 8. In this state, two AC motor drive pumps 5 share 90% of the flow rate of the coolant 4, and the DC motor drive pump 3 shares the remaining 10%.

When the main power supply 18 is lost due to a power failure or the like, power supply to the two AC motor drive pumps 5 is cut off. For this reason, each AC motor drive pump 5 rotates for a while due to the inertial energy stored in the flywheel, but its rotational speed gradually decreases due to consumption of this energy, and stops completely after several tens of seconds. It is thought that. On the other hand, even if the main power supply 18 is lost, the thermoelectric conversion element 1 of the thermoelectric power generation system 8 continues to generate power by the heat of the coolant 4, so that the power supply to the DC motor drive pump 3 is considered to be continued. Can be Therefore, the DC motor drive pump 3 continues to operate, and it is possible to secure a flow rate of 10% of the rated flow rate of the coolant 4.

When the main power supply 18 is lost, the reactor is designed to be scrammed and the output of the reactor core 19 is immediately reduced. However, the temperature of the core 19 does not decrease immediately due to the decay heat of the radioactive material. Further, since a considerable amount of heat energy is continuously stored in the coolant 4 and the structural material in the hot plenum of the reactor vessel 15, the DC motor drive pump 3 is operated for a while after the reactor is stopped. It is considered that about 10% of the flow rate of the primary coolant 4 at the rated time can be maintained. As a result, the heat removal capacity of the primary cooling system can be maintained at 10%.

The decay heat several tens of seconds after the reactor stop when each AC motor drive pump 5 completely stops is about 4% of the rated output.
It is considered to be. That is, even after each AC motor drive pump 5 stops, it is possible to obtain a heat removal capacity that exceeds the collapse heat output. Therefore, it is considered that the hot plenum temperature gradually decreases, and in response to this temperature decrease, the amount of power generated by the thermoelectric power generation system 8 decreases, and the flow rate of the coolant 4 by the DC motor drive pump 3 also gradually decreases. However, by the time the flow rate by the DC motor drive pump 3 decreases, it is considered that the temperature of the reactor core 19 has fallen sufficiently until the forced circulation of the coolant 4 by the DC motor drive pump 3 becomes unnecessary.

That is, while the core temperature is high and the coolant 4 needs to be circulated forcibly, the coolant 4 can be forcibly circulated using the heat generated in the core 19. is there. Therefore, it is not necessary to start the diesel generator and supply power to the pony motor of the main circulation pump at the same time as the main power supply is lost as in the conventional fast reactor plant. However, a fast reactor plant may be equipped with a diesel generator, but its role is only to supply power to air conditioners, etc., so it is not necessary to start the diesel generator at the same time as the main power is lost. Sexual requirements are greatly reduced compared to conventional ones.

[Effect on plant efficiency] Heat output 150,000k
Consider the case of a small fast reactor plant of W. Here, it is assumed that the energy conversion efficiency of the turbine generator is 42% and the energy conversion efficiency (net value in consideration of heat loss) of the thermoelectric conversion system is 8%. In-plant power (secondary cooling system pump, air-conditioning ventilation system, pre-heater, etc.) other than the primary cooling system pump power is also taken into consideration.

When the net plant efficiency was compared, it was 39.24% in the conventional plant, while it was 39.03% in the plant to which the primary cooling system circulation device of the present invention was applied. That is, in the plant to which the primary cooling system circulation device of the present invention is applied, the following effects were able to be obtained without substantially impairing the net plant efficiency as compared with the conventional plant. That is, the flow rate of the coolant 4 necessary for cooling the core at the time of the loss of the main power supply can be secured with high reliability. In addition, it is possible to reduce the pony motor of the main cooling pump of the primary cooling system, which was conventionally required, and it is also possible to eliminate the emergency battery equipment for driving the pony motor, or to replace the diesel generator with the pony motor. Since it is no longer necessary to use the motor for driving, the demand for reliability in starting the diesel generator can be greatly reduced as compared with the conventional case. Further, for these reasons, it was possible to realize a reduction in the physical quantity of the plant, a reduction in maintenance management, and an improvement in economic efficiency.

(Embodiment 2) In Embodiment 1 described above, a mechanical pump (AC motor drive pump, DC motor drive pump) is installed as a circulation pump, but an electromagnetic pump is used instead of a mechanical pump. That is, as shown in FIG.
Two AC motor driven pumps (mechanical pumps) 5 and one electromagnetic pump 3 are used in combination. In this case, 2
The main AC motor drive pump 5 is operated by the power of the main power supply 18 while the electromagnetic pump 3 is
Is operated by the AC current converted by the DC / AC converter 22. The structure of the thermoelectric generation system 8 is the same as that of the first embodiment.
The description is omitted.

In the present embodiment, the sharing ratio of the flow rate during the rated operation is set to 45% for the two mechanical pumps 5 and 10% for the electromagnetic pump 3 respectively. Although the efficiency of the electromagnetic pump 3 is lower than that of the mechanical pump, the electromagnetic pump 3 has high reliability because there is no failure such as sticking of a bearing in the mechanical pump 5. Estimated net plant efficiency in this case was 38.82%. This value is lower than if all main circulation pumps were mechanical, due to the use of electromagnetic pumps, which were less efficient than mechanical pumps, and had a minimal effect on net plant efficiency. I found it.

(Embodiment 3) All of the circulation pumps are electromagnetic pumps. That is, the power generated by each thermoelectric conversion element 1 is converted into AC by a DC / AC converter 22, and this is used as a power source to drive the electromagnetic pump 3, which can be operated even when the main power is lost, and the main power (AC) 18. The two electromagnetic pumps 5 serving as sources are combined. In this case, since all are electromagnetic pumps, the two electromagnetic pumps 3 driven by the main power supply 18 are considered to stop instantaneously when the main power supply is lost. This is conditionally stricter from the viewpoint of maintaining the soundness of the core 19 as compared with the system in which the mechanical pump with a flywheel continues to rotate for a fixed time due to inertia even immediately after the power is lost. Therefore, the share ratio of the flow rate during the rated operation is 40% for each of the two electromagnetic pumps 5 and 20% for the one electromagnetic pump 3, and the share of the electromagnetic pumps 3 is higher than that in each of the above-described embodiments. Estimated net plant efficiency in this case was 38.46%. The results were lower than when a mechanical pump was used, but this was due to the use of an electromagnetic pump that was less efficient than the mechanical pump, and the net effect on plant efficiency was found to be small. The structure and operating conditions of the thermoelectric generation system 8 were the same as those in the first embodiment.

(Embodiment 4) In each of the above embodiments, only one DC motor drive pump 3 is installed as a circulating pump driven by the power of the thermoelectric power generation system 8, but it is driven by the power of the thermoelectric conversion element 1. Two or more pumps may be installed.

(Embodiment 5) Three or more circulation pumps driven by the power of the main power supply 18 may be provided.

[0045]

As described above, in the primary coolant circulating device of the fast reactor according to the first aspect of the present invention, the power generated by the thermoelectric power generation system using the heat stored in the coolant is used as the circulating pump. Since the circulating pump is operated as a power source, the primary coolant for cooling the core can be circulated using the heat of the coolant without using the main power supply.
For this reason, it becomes possible to reliably maintain the minimum flow rate of the coolant necessary for cooling the core when the main power supply is lost. In addition, the need for a pony motor for the primary main circulation pump, an emergency battery unit or a diesel generator for driving the pony motor, which is conventionally required, can be eliminated. In this way, the economy can be improved. In addition, diesel generators are sometimes used to supply power to air conditioning equipment in plants, but they are not used to drive pony motors. Can be greatly reduced.

Further, in the primary coolant circulating device of the fast reactor according to the second aspect, the circulating pump is a DC motor driven pump operated by the DC current generated by the thermoelectric power generation system, and thus the power is generated by the thermoelectric power generation system. The DC motor drive pump, which is the main circulation pump, can be directly driven by the DC current.

Further, in the primary coolant circulating device of the fast reactor according to the third aspect, the circulating pump is operated by an AC pump obtained by converting a DC current generated by the thermoelectric power generation system by a DC / AC converter or an AC pump. Since the pump is a motor-driven pump, an electromagnetic pump or an AC motor-driven pump operated by an AC current can be used as the main circulation pump.

Further, in the primary cooling and circulating apparatus of the fast reactor according to the fourth aspect, the thermoelectric power generation system includes a thermoelectric conversion element for generating electric power by a temperature difference between both surfaces, and a thermoelectric conversion element stored in a coolant on one side surface of the thermoelectric conversion element. And a low-temperature side heat conduction unit for cooling the other side surface of the thermoelectric conversion element, wherein the high-temperature side heat conduction unit and the low-temperature side heat conduction unit comprise a thermal stress relaxation pad having a functionally graded material. Is joined to the thermoelectric conversion element, so that the thermal stress generated due to the temperature difference between the thermoelectric conversion elements can be dispersed and absorbed by the functionally graded material. For this reason, the joining state between each heat conducting means and the thermoelectric conversion element is hardly broken, and the durability can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of an embodiment of a primary coolant circulation device according to the present invention.

FIG. 2 is a cross-sectional view of the thermoelectric power generation system of the primary coolant circulation device according to the present invention.

FIG. 3 is a perspective view of a thermoelectric conversion module included in the thermoelectric power generation system of FIG.

FIG. 4 is a cross-sectional view of a thermoelectric conversion element included in the thermoelectric conversion module of FIG.

FIG. 5 is a sectional view showing another embodiment of the thermoelectric conversion element.

FIG. 6 is a block diagram showing a first embodiment of a primary coolant circulation device according to the present invention.

7 is a diagram showing, from above, a positional relationship between the thermoelectric power generation system of the primary coolant circulation device and each pump in FIG. 6;

8 is a perspective view showing a heat radiating panel of a heat radiating heat pipe of the thermoelectric power generation system of FIG.

FIG. 9 is a block diagram showing a second embodiment of the primary coolant circulation device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermoelectric conversion element 2 Heat pipe for heat collection (high-temperature side heat conduction means) 3 Circulation pump 4 Coolant 7 Heat dissipation heat pipe (low-temperature side heat conduction means) 8 Thermoelectric power generation system 10, 11 Thermal stress relaxation pad 12, 13 Incline Functional materials

Claims (4)

[Claims] 1. A primary coolant circulation device for a fast reactor having a plurality of circulation pumps, wherein the circulation pump uses electric power generated by a thermoelectric power generation system using heat stored in a coolant as a power source. A primary coolant circulation device for a fast reactor, comprising a circulation pump to be operated. 2. The primary coolant circulating device according to claim 1, wherein the circulating pump is a DC motor driven pump that operates by a DC current generated by the thermoelectric power generation system. 3. The circulating pump according to claim 1, wherein the circulating pump is an electromagnetic pump or an AC motor driven pump operated by an AC current obtained by converting a DC current generated by the thermoelectric power generation system by a DC / AC converter. 2. The primary coolant circulation device of the fast reactor according to 1. 4. The thermoelectric power generation system includes: a thermoelectric conversion element that generates electric power based on a temperature difference between both surfaces; a high-temperature side heat conduction unit that guides heat stored in a coolant to one side surface of the thermoelectric conversion element; Low-temperature heat conduction means for cooling the other side surface of the conversion element, wherein the high-temperature heat conduction means and the low-temperature heat conduction means are joined to the thermoelectric conversion element with a thermal stress relaxation pad having a functionally graded material interposed therebetween. The primary coolant circulating device according to any one of claims 1 to 3, wherein: