JP4001305B2 - Fast reactor primary coolant circulation system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
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 for a fast reactor that circulates a coolant even when main power is lost such as a power failure.
[0002]
[Prior art]
The primary coolant circulation system for the fast reactor must ensure the minimum coolant flow rate necessary to maintain the soundness of the core even when the main power supply is lost due to a power failure or the like. For this reason, in the conventional primary coolant circulation device for a fast reactor, a flywheel and a pony motor are installed in a mechanical pump that circulates the coolant in the primary cooling system. That is, even after the main power supply is lost, the pump is continuously driven for a certain period of time due to the rotational inertia of the flywheel, and the diesel generator is started up for a short time (about several tens of seconds) until the inertial energy disappears, or the power is The supply source is switched to the emergency battery, and the pony motor is operated by such electric power to maintain the rotation of the pump, so that about 10% of the rated flow rate is secured as the flow rate of the coolant.
[0003]
Diesel generators that are started up due to the loss of the main power supply are designed to start up reliably in a short time. The emergency battery serving as the power supply source of the pony motor is designed so that the pony motor can be continuously operated over a required time. And in an actual fast reactor plant, it combines with these, and it has the design which gives multiplicity and raises the safety | security of a plant more.
[0004]
[Problems to be solved by the invention]
However, in the fast reactor plant, it is particularly important to maintain the reliability of the equipment, and for that purpose, a great deal of labor is required for maintenance management of diesel generators, emergency batteries, pony motors, and the like. Moreover, it is desirable to eliminate the need for a diesel generator and an emergency battery from the viewpoint of reducing the amount of plant material and economy. For these reasons, there is a demand for the development of a primary coolant circulation device that is more reliable and easier to maintain.
[0005]
An object of the present invention is to provide a primary coolant circulating apparatus with a simple structure and high reliability.
[0006]
[Means for Solving the Problems]
In order to achieve this object, a primary coolant circulation device for a fast reactor according to claim 1 is stored in a coolant as the circulation pump in the primary coolant circulation device for a fast reactor having a plurality of circulation pumps. Pump that is operated using the power generated by the thermoelectric power generation system using the generated heat as a power source And a circulation pump operated by an alternating current from the main power supply It is a configuration.
[0007]
Therefore, as long as heat is stored in the coolant, the thermoelectric power generation system generates power and continues to drive the circulation pump that circulates the coolant. That is, even if the main power supply 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 circulation pump uses the primary coolant. Continue cooling to keep the core cool.
[0008]
In this case, as in the primary cooling and circulating apparatus of the fast reactor according to claim 2, Operated using power generated by the thermoelectric power generation system as a power source The circulation pump is preferably a direct current motor drive pump that operates by direct current generated by the thermoelectric power generation system. In this case, it is possible to directly drive the DC motor drive pump, which is a circulation pump, by the DC current generated by the thermoelectric power generation system.
[0009]
Moreover, like the primary cooling and circulation device of the fast reactor according to claim 3, Operated using power generated by the thermoelectric power generation system as a power source The circulation pump is preferably an electromagnetic pump or an AC motor drive pump operated by an AC current obtained by converting a DC current generated by the thermoelectric power generation system by a DC / AC converter. In this case, since alternating current can be generated, an electromagnetic pump or an alternating current motor drive pump can also be used as the main circulation pump.
[0010]
Furthermore, in the primary cooling and circulating apparatus of the fast reactor according to claim 4, the thermoelectric power generation system includes a thermoelectric conversion element that generates power by a temperature difference between both surfaces, and heat stored in the coolant on one side surface of the thermoelectric conversion element. A high temperature side heat conduction means for guiding, and a low temperature side heat conduction means for cooling the other side surface of the thermoelectric conversion element. The high temperature side heat conduction means and the low temperature side heat conduction means sandwich the thermal stress relaxation pad having the functional gradient material. It is the structure joined to the thermoelectric conversion element.
[0011]
Therefore, a temperature difference is generated between one side surface of the thermoelectric conversion element heated by the heat of the coolant guided by the high temperature side heat conduction unit and the other side surface cooled by the low temperature side heat conduction unit. Due to this temperature difference, the thermoelectric conversion element generates power and operates the circulation pump. Thermal stress is generated in the thermoelectric conversion element due to the temperature difference between both surfaces, and this thermal stress is absorbed by the functionally gradient material of each thermal stress relaxation pad.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail based on the best mode shown in the drawings.
[0013]
FIG. And FIG. 1 shows an example of an embodiment of a primary coolant circulating apparatus for a fast reactor to which the present invention is applied. This fast reactor is a tank type fast breeder reactor that uses, for example, liquid sodium as the coolant 4 of the primary cooling system that cools the core 19 in the reactor vessel 15, and the primary coolant circulation device has a plurality of circulation units. A circulation pump 3 that includes a pump and that is operated using the electric power generated by the thermoelectric power generation system 8 using the heat stored in the coolant 4 as a power source. And a circulation pump 5 operated by an alternating current from the main power source 18. Yes. Here, the circulation pump 3 is a direct current motor drive pump when the direct current generated by the thermoelectric power generation system 8 is used as it is, and an electromagnetic when the direct current is converted into alternating current via the D / A converter. A pump or an AC motor driven pump is used.
[0014]
As shown in FIG. 2, the thermoelectric power generation system 8 includes a thermoelectric conversion module 6, a heat collecting heat pipe 2 that is a high-temperature side heat conducting means, and a heat radiation heat pipe 7 that is a low-temperature side heat conducting means. Has been. The thermoelectric conversion module 6 is a set of many thermoelectric conversion units 9 as shown in FIG. 3, and each thermoelectric conversion unit 9 has a high temperature side thermal stress on both sides of the thermoelectric conversion element 1 as shown in FIG. The relaxation pad 10 and the low temperature side thermal stress relaxation pad 11 are joined.
[0015]
The thermoelectric conversion element 1 is an element that generates power based on 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 is selected is determined according to the operating temperature region and the like. Each element is composed of a P-type semiconductor having a high hole concentration and an N-type semiconductor having a high electron concentration, and generates an electromotive force by a combination of both. In practice, the output is increased by electrically connecting a plurality of pairs of P-type semiconductor and N-type semiconductor in series.
[0016]
Each thermal stress relaxation pad 10, 11 is composed of functionally gradient materials 12, 13 and a graphite layer 14. The graphite layer 14 of each thermal stress relaxation pad 10, 11 is disposed between each functionally gradient material 12, 13 and the thermoelectric conversion element 1, and prevents diffusion of the components of the thermoelectric conversion element 1.
[0017]
Each of the functionally gradient materials 12 and 13 is obtained by gradually changing the composition ratio of the thermal stress relaxation material / heat conductor and the electrical insulating material in the thickness direction. A material having a large modulus 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 heat conductive thermal stress relaxation material / heat conductor, thermal stress can be relaxed while maintaining high thermal conductivity. However, when a SiGe element or the like having a high operating temperature is used as the thermoelectric conversion element 1, the operating temperature of the high temperature side thermal stress relaxation pad 10 approaches the melting point of copper. For the high temperature side thermal stress relaxation pad 10, it is preferable to use palladium having excellent performance next to copper. However, as a matter of course, the material used as the thermal stress relaxation material / heat conductor is not necessarily limited to copper or palladium. In this case, a material having a large thermal conductivity and a small elastic constant, that is, a material having a smaller ratio of the elastic constant to the thermal conductivity is more preferable. Further, the metal is not necessarily limited to metal as long as it satisfies this property. On the other hand, the electrical insulating material is alumina, for example, and ceramics such as silicon nitride and silicon carbide can be applied in addition to alumina. Various ceramics such as silicon carbide are preferable materials because they have good thermal conductivity, little deformation due to heat, and excellent electrical insulation. However, as a matter of course, the material used as the electrical insulating material is not necessarily limited to ceramics such as alumina and silicon nitride. The functionally gradient materials 12 and 13 of the present embodiment are made of copper (Cu) layers (hereinafter referred to as Cu layers) 12a and 13a, which are thermal stress relaxation materials and thermal conductors, on the thermoelectric conversion element 1 side. The heat heat pipe 2 or the heat radiation heat pipe 7 side is made of alumina (Al ₂ O _Three ) Layers (hereinafter referred to as alumina layers) 12b and 13b, and between the Cu layers 12a and 13a and the alumina layers 12b and 13b are layers 12c and 13c that gradually change the composition ratio of copper and alumina. . The Cu layers 12a and 13a also function as electrodes that electrically connect the thermoelectric conversion elements 1P and 1N in series.
[0018]
Copper (thermal stress relaxation material and heat conductor) and alumina (electrical insulating material) constituting the functionally gradient materials 12 and 13 of the thermal stress relaxation pads 10 and 11 can all be obtained in a powder state. . Therefore, the functionally gradient materials 12 and 13 can be manufactured by powder metallurgy. For example, using a device for injecting 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, layered or plate-like pellets (powder lump) are produced by gradually changing the filling ratio of each powder from the inner side in the thickness direction toward the both outer sides by controlling the injection ratio of both nozzles. After the pellets are compression molded, the functionally gradient materials 12 and 13 can be obtained by heating the pellets in a furnace and sintering them.
[0019]
In the functionally gradient materials 12 and 13 manufactured in this way, the composition ratio of the thermal stress relaxation material / heat conductor and the insulating material, which have greatly different linear expansion coefficients, is gradually changed. When used as the relaxation pads 10 and 11, the thermal stress generated inside can be dispersed without concentrating on a specific location.
[0020]
The heat collecting heat pipe 2 is joined to one side surface (high temperature side surface) of each thermoelectric conversion element 1 with the high temperature side thermal stress relaxation pad 10 interposed therebetween, and guides the heat stored in the coolant 4 to the high temperature side surface. The heat radiation 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.
[0021]
Next, the operation of the primary coolant circulation device will be described.
[0022]
The heat of the coolant 4 is transmitted to the high temperature side surface of each thermoelectric conversion element 1 of the thermoelectric power generation system 8 by the heat collecting heat pipe 2, and the heat on the low temperature side of each thermoelectric conversion element 1 is removed by the heat dissipation heat pipe 7. Is done. Therefore, a temperature difference is generated 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 if the main power source 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 using the heat, and the circulation pump 3 is connected to the coolant. 4 is circulated to continue cooling the core.
[0023]
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 scope of the present invention. For example, in the above description, it is applied to a tank type fast reactor, but it can also be applied to a loop type or hybrid type fast reactor. However, when applied to a loop reactor, the pump 3 driven by the electric power of the thermoelectric power generation system 8 needs to be installed in the reactor vessel 15. For this reason, depending on the structure of the reactor vessel 15, it may be necessary to devise a little to secure the installation space for such a pump. For example, in the case of a “bottom inflow type” loop fast reactor in which the primary main pipe is connected to the lower part of the reactor vessel 15, the diameter of the reactor vessel 15 needs to be slightly increased. On the other hand, the “top entry method” in which the primary main pipe is connected to the side surface of the reactor vessel 15 or the “top entry method” loop type fast reactor that passes through the shielding plug 21 and flows into the reactor vessel 15 from above. In some cases, since a sufficient space is originally secured in the reactor vessel, the installation of such a pump is relatively easy.
[0024]
In the above description, as the functionally gradient materials 12 and 13 of the thermal stress relaxation pads 10 and 11 sandwiching the thermoelectric conversion element 1, the thermal stress relaxation material / heat conductor and the electrical insulation material from one side surface to the other side surface. However, for example, these composition ratios may be changed from the inside in the thickness direction toward the both outsides. For example, as shown in FIG. 5, alumina (electrical insulating material) layers 12b and 13b are formed at the center in the thickness direction of the functionally gradient materials 12 and 13, and alumina and Cu (thermal stress relaxation material / heat) are formed on both sides thereof. The layers 12c and 13c for gradually changing the composition ratio of the conductor) may be formed, and the Cu layers 12a and 13a may be formed outside these layers. In this case, the direction of change in the composition ratio is reversed halfway in the thickness direction of each functionally graded material 12, 13 in the middle, that is, the ratio of the electrical insulating material to the thermal stress relaxation material / heat conductor is increased. It can be changed on the way whether it tends to decrease or to decrease. That is, the functionally gradient materials 12 and 13 have a structure in which the Cu (metal) layers 12a and 13a are arranged on both sides of the alumina (ceramic) layers 12b and 13b. In the cooling process from the sintering temperature at the time of manufacture to the room temperature, the metal It is possible to prevent the occurrence of warpage and cracks due to the difference in thermal expansion between ceramic and ceramic. For this reason, manufacture of each functionally gradient material 12 and 13 becomes easy, cost reduction becomes possible, soundness is also improved, and a stable product can be obtained. Further, since both the outer sides of the functionally gradient materials 12 and 13 can be formed into metal (Cu) layers 12a and 13a, that is, the materials on the outer sides of the functionally gradient materials 12 and 13 are used as the heat collecting heat pipe 2 or the heat radiating heat pipe. 7 can be made of the same material or a linear expansion coefficient, so that the high temperature side thermal stress relaxation pad 10 and the heat collecting heat pipe 2, the low temperature side thermal stress relaxation pad 11 and the heat radiating heat pipe 7 While joining becomes easy, these joint strengths can be increased. Further, it is not always necessary to form the alumina layers 12b and 13b in 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 need not be the same, and may be changed from each other. Further, the ratio of the change in the composition ratio of the layers 12c and 13c on both sides is not necessarily the same between the thermoelectric element 1 side and the heat collecting heat pipe 2 or the heat radiating heat pipe 7 side. Of course it is good. The Cu layers 12a and 13a made of the above-described thermal stress relaxation material / heat conductor and the alumina layers 12b and 13b made of an electrical insulating material do not necessarily need to be made of 100% Cu or alumina. An electrical insulating material or the like may be included as long as the function as a thermal stress relaxation material and thermal conductor can be secured, or a thermal stress relaxation material and thermal conductor as long as the function as an electrical insulation material can be substantially secured. But of course.
[0025]
Furthermore, in the above description, the thermoelectric power generation system 8 includes the thermoelectric conversion element 1, the heat collecting heat pipe 2 that is the high temperature side heat conducting means, and the heat radiation heat pipe 7 that is the low temperature side heat conducting means. 7 are bonded to the thermoelectric conversion element 1 with the thermal stress relaxation pads 10 and 11 having the functionally gradient materials 12 and 13 interposed therebetween, but the thermal stress relaxation pads 10 and 11 having the functionally gradient materials 12 and 13 are omitted. Of course, you may do.
[0026]
【Example】
Example 1
[Configuration of primary coolant circulation system]
As shown in FIGS. 6 and 7, a total of three mechanical main circulation pumps are installed as main circulation pumps of the primary coolant circulation device, and one of them is generated by a direct current generated by the thermoelectric power generation system 8. A circulating pump (hereinafter referred to as a DC motor drive pump) 3 to be operated was used, and the remaining two units were set to a circulation pump (hereinafter referred to as an AC motor drive pump) 5 that was operated by an AC current from the main power supply 18. Although the conventional main circulation pump is provided with a flywheel and a pony motor when the main power supply is lost, the DC motor drive pump 3 according to this embodiment omits both the flywheel and the pony motor. For the AC motor-driven pump 5, only the pony motor was omitted. The two AC motor drive pumps 5 were set to share 90% (45% each) of the primary cooling system rated flow rate, and the DC motor drive pump 3 to share the remaining 10%.
[0027]
[Structure of thermoelectric power generation system]
21 thermoelectric conversion modules 6 of the thermoelectric conversion system 8 were accommodated in the casing 20 shown in FIG. 1 and installed on the reactor shielding plug 21. Each thermoelectric conversion module 6 is 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, and the output of one thermoelectric conversion module 6 is about 2.88 kW. Therefore, the output of about 60 MW can be obtained with 21 modules 6. The size of the thermoelectric conversion module 6 is 30 cm in length and 13 cm in width. By arranging three rows in the vertical direction and seven rows in the horizontal direction, the 21 heat transfer conversion modules 6 are 1 m above the reactor shielding plug 21. It was possible to install it in a square space.
[0028]
Six heat collecting heat pipes 2 were installed for each thermoelectric conversion module 6 and 126 thermoelectric power generation system 8 as a whole. At this time, the heat collecting heat pipes 2 were installed so as to be bundled in a rectangular shape with a predetermined distance between them. Further, the lower end of each heat collecting heat pipe 2 is inserted into the hot plenum of the reactor vessel 15 through the shielding plug 21, while the upper end of each of the heat collecting heat pipes 2 is inserted into the hot-side thermal stress relaxation pad 10 of the thermoelectric conversion unit 9. The thermoelectric conversion elements 1 were sandwiched and joined to one side surface. Each heat collecting heat pipe 2 was filled with cesium as a working fluid. However, lithium or the like may be enclosed instead of cesium.
[0029]
Seven heat pipes 7 for heat dissipation were installed for each thermoelectric conversion module 6 and 147 were installed for the thermoelectric power generation system 8 as a whole. At this time, the heat dissipating heat pipes 7 were installed so as to be bundled in a substantially rectangular shape with a predetermined distance between them. Each of these heat radiation heat pipes 7 was accommodated in the inner passage of the double duct 16, and the lower end thereof was joined to the other side of the corresponding thermoelectric conversion element 1, that is, the low temperature side. That is, each heat dissipation 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. Further, as shown in FIG. 8, a heat radiating panel 17 was fixed in the vicinity of the upper end of each heat radiating heat pipe 7. Water was sealed as a working fluid sealed in each heat dissipation heat pipe 7. However, it goes without saying that it is not limited to water.
[0030]
The double duct 16 that accommodates the heat pipe 7 for heat dissipation has its inner and outer passages communicated at its lower end, while its upper end protrudes outside the reactor building and opens the inner and outer passages to the atmosphere. is doing. Accordingly, in the double duct 16, cold outside air descends the outer passage, reverses at the lower end portion, flows into the inner passage, and is heated and discharged while cooling the heat dissipating heat pipe 7. That is, each heat dissipating heat pipe 7 can remove heat by natural circulation of outside air.
[0031]
When applied to a small fast reactor having an electrical 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. Assuming that the energy conversion efficiency of the thermoelectric conversion module 6 is 8%, the thermoelectric power generation system 8 generates 60 kW. The remaining 690 kW of thermal energy is transmitted to the outside of the reactor containment vessel 15 by the heat radiating heat pipe 7 and released. The axial heat flux of the heat collecting heat pipe 2 in this case is 300 W / cm. ² Degree. Therefore, 126 heat pipes having an inner diameter of 50 mm can be arranged in a square section space of 1 m square while leaving a gap therebetween. Such a cross-sectional dimension is smaller than the diameter of each circulation pump 3, 5 and can be easily installed in the reactor vessel 15. The same applies to the heat collecting heat pipe 2.
[0032]
[Operating conditions]
The temperature of the liquid sodium which is the coolant 4 in the reactor vessel hot plenum in the normal operation state is about 530 ° C. This heat was guided to one side surface of each thermoelectric conversion element 1 by the heat collecting heat pipe 2. In addition, the temperature of the atmosphere (outside air) in which the outer passage and the inner side of the double duct 16 are open is about 30 ° C., and the heat of the other end face of each thermoelectric conversion element 1 is transmitted through the heat pipe 7 for heat dissipation and the double duct 16. And discharged into the atmosphere. Therefore, a temperature difference capable of generating power was generated between both surfaces of each thermoelectric conversion element 1.
[0033]
[Operation]
When the nuclear reactor is normally operated, the two AC motor drive pumps 5 are driven by electric power supplied from the main power supply (AC) 18, and the DC motor drive pump 3 is a thermoelectric generator of the thermoelectric power generation system 8. It is driven by a DC power source supplied from the conversion element 1. In this state, 90% of the flow rate of the coolant 4 is shared by the two AC motor drive pumps 5, and the remaining 10% is shared by the DC motor drive pump 3.
[0034]
When the main power source 18 is lost due to a power failure or the like, the 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 is gradually reduced due to the consumption of this energy, and completely stops after several tens of seconds. I think 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. It is done. Therefore, the DC motor drive pump 3 can continue to operate, and a flow rate of 10% of the rated flow rate of the coolant 4 can be secured.
[0035]
In addition, when the main power supply 18 is lost, the reactor is scrammed and the power of the core 19 is designed to immediately decrease. 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 thermal 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 operates for a while after the reactor is shut down. It is considered that it is possible to maintain about 10% of the flow rate of the primary coolant 4 at the time of rating. Thereby, 10% of the heat removal capability by the primary cooling system can be maintained.
[0036]
It is considered that the decay heat after several tens of seconds after the reactor stop when each AC motor-driven pump 5 is completely stopped is about 4% of the rated output. That is, even after each AC motor drive pump 5 is stopped, it is possible to obtain a heat removal capability exceeding the decay heat output. For this reason, it is considered that the hot plenum temperature gradually decreases, the amount of power generated by the thermoelectric power generation system 8 decreases in response to this temperature decrease, and the flow rate of the coolant 4 by the DC motor drive pump 3 also decreases gradually. However, when the flow rate by the DC motor drive pump 3 decreases, it is considered that the temperature of the core 19 is sufficiently lowered until the forced circulation of the coolant 4 by the DC motor drive pump 3 is not necessary.
[0037]
That is, while the core temperature is high and it is necessary to forcibly circulate the coolant 4, it is possible to forcibly circulate the coolant 4 using the heat generated in the core 19. Therefore, unlike the conventional fast reactor plant, it is not necessary to start the diesel generator and supply power to the pony motor of the main circulation pump simultaneously with the loss of the main power supply. However, a fast reactor plant may be equipped with a diesel generator, but its role is limited to supplying power to air conditioning equipment, etc., so it is not always necessary to start the diesel generator as soon as the main power is lost. The demand for sex is greatly reduced compared to the conventional one.
[0038]
[Influence on plant efficiency]
Consider the case of a small fast reactor plant with a thermal output of 150,000 kW. Here, it is assumed that the energy conversion efficiency of the turbine generator is 42%, and the energy conversion efficiency of the thermoelectric conversion system (net value in consideration of heat loss) is 8%. In-house power (secondary cooling system pump, air conditioning ventilation system, preheating heater, etc.) other than the pump power of the primary cooling system is also taken into consideration.
[0039]
Comparing the net plant efficiency, it was 39.24% in the conventional plant, and 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 was applied, the following effects could be obtained without substantially losing the net plant efficiency as compared with the conventional plant. That is, the flow rate of the coolant 4 which is the minimum necessary for cooling the core when the main power is lost 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 that has been required in the past, and it is possible to delete 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 reliability requirement for starting the diesel generator can be greatly reduced as compared with the prior art. Furthermore, because of these, it was possible to reduce the amount of plant material, reduce maintenance, and improve economy.
[0040]
(Example 2)
In the first embodiment 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 the mechanical pump. That is, as shown in FIG. 9, two AC motor-driven pumps (mechanical pumps) 5 and one electromagnetic pump 3 are used in combination. In this case, the two AC motor-driven pumps 5 are operated by the electric power of the main power supply 18, while the DC current generated by the thermoelectric conversion element 1 of the electromagnetic pump 3 is converted by the DC / AC converter 22 while the electromagnetic pump 3 is operated. Operated by alternating current. In addition, the structure of the thermoelectric power generation system 8 is the same as that of Example 1, The description is abbreviate | omitted.
[0041]
In this embodiment, the flow rate sharing ratio during rated operation is set to 45% for the two mechanical pumps 5 and 10% for the electromagnetic pump 3, respectively. The electromagnetic pump 3 is inferior in efficiency as compared with the mechanical pump, but has high reliability because there is no failure such as bearing fixation in the mechanical pump 5. The net plant efficiency in this case was estimated to be 38.82%. This value is lower than when all main circulation pumps are mechanical, but this is due to the use of electromagnetic pumps that are less efficient than mechanical pumps and has a negligible impact on net plant efficiency. I found out.
[0042]
(Example 3)
All circulation pumps are electromagnetic pumps. That is, the electric power generated by each thermoelectric conversion element 1 is converted into alternating current by the DC / AC converter 22, and this is used as a power source to drive the electromagnetic pump 3 that can be operated even when the main power source is lost and the main power source (AC) 18. Combined with two electromagnetic pumps 5 as sources. In this case, since all are electromagnetic pumps, it is considered that the two electromagnetic pumps 3 using the main power source 18 as a power source stop instantaneously when the main power source is lost. This is conditionally severe from the viewpoint of maintaining the soundness of the core 19 as compared with a method in which a mechanical pump with a flywheel continues to rotate only for a certain period of time even after power is lost. Therefore, the sharing ratio of the flow rate at the rated operation is 40% for the two electromagnetic pumps 5 and 20% for the one electromagnetic pump 3, and the sharing of the electromagnetic pump 3 is higher than that of the above-described embodiments. The net plant efficiency in this case was estimated to be 38.46%. The result was 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 effect on net plant efficiency was negligible. The structure and operating conditions of the thermoelectric power generation system 8 were the same as in Example 1.
[0043]
(Example 4)
In each of the above-described embodiments, only one DC motor drive pump 3 is installed as a circulation pump driven by the electric power of the thermoelectric power generation system 8, but two or more pumps driven by the electric power of the thermoelectric conversion element 1 are installed. Also good.
[0044]
(Example 5)
This may be the case where three or more circulation pumps driven by the power of the main power supply 18 are installed.
[0045]
【The invention's effect】
As described above, in the primary coolant circulation device of the fast reactor according to claim 1, the circulation pump is operated using the electric power generated by the thermoelectric power generation system using the heat stored in the coolant as the power source. Circulating pump And a circulation pump that is operated by alternating current from the main power supply Therefore, it is possible to circulate the primary coolant that cools the core using the heat of the coolant without using the main power source. For this reason, when the main power supply is lost, the minimum flow rate of the coolant necessary for cooling the core can be ensured with high reliability. In addition, the pony motor for the primary main circulation pump and the emergency battery equipment or diesel generator for driving the primary main circulation pump, which were necessary in the past, can be eliminated, so that the quantity of the plant can be reduced and maintenance management is easy. Thus, the economy can be improved. In addition, diesel generators are sometimes used to supply power to air conditioning facilities in plants, but are not used to drive pony motors. Compared with, it can be greatly reduced.
[0046]
Moreover, in the primary coolant circulation device of the fast reactor according to claim 2, Operated using power generated by the thermoelectric power generation system as a power source Since the circulation pump is a direct current motor drive pump that operates by direct current generated by the thermoelectric power generation system, the direct current motor drive pump that is the main circulation pump can be directly driven by the direct current generated by the thermoelectric generation system.
[0047]
Moreover, in the primary coolant circulation device of the fast reactor according to claim 3, Operated using power generated by the thermoelectric power generation system as a power source Since the circulation pump is an electromagnetic pump or an AC motor drive pump that is operated by an AC current obtained by converting a DC current generated by a thermoelectric power generation system by a DC / AC converter, an electromagnetic pump or an AC that operates by an AC current as a main circulation pump A motor driven pump can be used.
[0048]
Furthermore, in the primary cooling and circulating apparatus of the fast reactor according to claim 4, the thermoelectric power generation system includes a thermoelectric conversion element that generates power by a temperature difference between both surfaces, and heat stored in the coolant on one side surface of the thermoelectric conversion element. A high temperature side heat conduction means for guiding, and a low temperature side heat conduction means for cooling the other side surface of the thermoelectric conversion element. The high temperature side heat conduction means and the low temperature side heat conduction means sandwich the thermal stress relaxation pad having the functional gradient material. Since it is joined to the thermoelectric conversion element, thermal stress generated due to the temperature difference of the thermoelectric conversion element can be dispersed and absorbed by the functionally gradient material. For this reason, it becomes difficult to destroy the joining state of each heat conduction means and the thermoelectric conversion element, and 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 circulating apparatus according to the present invention.
FIG. 2 is a cross-sectional view of a thermoelectric power generation system of a primary coolant circulation device according to the present invention.
FIG. 3 is a perspective view of a thermoelectric conversion module constituting the thermoelectric power generation system of FIG. 2;
4 is a cross-sectional view of a thermoelectric conversion element constituting the thermoelectric conversion module of FIG. 3;
FIG. 5 is a cross-sectional view showing another embodiment of a thermoelectric conversion element.
FIG. 6 is a block diagram showing a first embodiment of a primary coolant circulating apparatus according to the present invention.
7 is a diagram showing a positional relationship between the thermoelectric power generation system and each pump of the primary coolant circulating apparatus in FIG. 6 from above. FIG.
8 is a perspective view showing a heat dissipation panel of a heat pipe for heat dissipation in the thermoelectric power generation system of FIG. 6. FIG.
FIG. 9 is a block diagram showing a second embodiment of the primary coolant circulating apparatus according to the present invention.
[Explanation 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 pipe for heat dissipation (low temperature side heat conduction means)
8 Thermoelectric power generation system
10,11 Thermal stress relaxation pad
12, 13 Functionally graded material

Claims (4)

In the primary coolant circulation device of a fast reactor having a plurality of circulation pumps, the circulation pump is operated by using the power generated by the thermoelectric power generation system as a power source using the heat stored in the coolant. And a primary coolant circulating device for a fast reactor, comprising a circulating pump operated by an alternating current from a main power source . 2. The high-speed pump according to claim 1, wherein the circulating pump operated by using the electric power generated by the thermoelectric power generation system as a power source is a direct current motor drive pump operated by a direct current generated by the thermoelectric power generation system. Primary coolant circulation device for the furnace. The circulating pump operated using the electric power generated by the thermoelectric power generation system as a power source is an electromagnetic pump or an AC motor driven that is operated by an AC current obtained by converting a DC current generated by the thermoelectric power generation system by a DC / AC converter. The primary coolant circulating apparatus for a fast reactor according to claim 1, wherein the primary coolant circulating apparatus is a pump.   The thermoelectric power generation system includes a thermoelectric conversion element that generates power based on a temperature difference between both surfaces, high-temperature side heat conduction means that guides heat stored in a coolant to one side surface of the thermoelectric conversion element, and another side surface of the thermoelectric conversion element. A low-temperature side heat conduction means for cooling, wherein the high-temperature side heat conduction means and the low-temperature side heat conduction means are joined to the thermoelectric conversion element with a thermal stress relaxation pad having a functionally gradient material interposed therebetween. The primary coolant circulating apparatus for a fast reactor according to any one of claims 1 to 3.

Images