JP2011021901A - Passive cooling system for liquid metal cooled reactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a passive cooling system for a liquid metal cooled reactor which is free from the failure in a passive cooling function even if the air temperature in the vicinity of a reactor building rises due to an accident around it and the like. <P>SOLUTION: In the passive cooling system 2 which cools by releasing a gas outside by way of an exhaust pipe 115 and an air exhaust vent 116 after forming a downward flow passage 113 of a gas cooling passage 111 between heat collectors 112, provided between a containment vessel 105 containing a reactor vessel 102 and a silo 106, and the silo 106 and an upward flow passage 114 between the heat collectors 112 and the containment vessel 105, respectively, introducing the outside air by way of air intakes 7 and an intake pipe 8 to the downward flow passage 113 and allowing it to flow down and to circulation through the upward flow passage 114, the air intakes 7 are laid out at some clearances both to each other and to the air exhaust vent 116 and also at a prescribed or longer distance from the containment vessel 105 which is insusceptible to the impact of an aircraft accident and the like in the vicinity of the containment vessel 105. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a passive cooling system for a liquid metal cooled nuclear reactor that passively cools a reactor vessel by introducing air from the outside.

  Conventionally, for example, as shown in a longitudinal sectional view in FIG. 10, a liquid metal cooled nuclear reactor 100 is constituted by a nuclear fuel assembly in a reactor vessel 102 filled with a liquid metal coolant 101 such as sodium or sodium / potassium. The reactor core 103 is held, and the reactor vessel 102 is stored in a containment vessel (guard vessel) 105 with a gap 104 filled with an inert gas therebetween, and the containment vessel 105 is dug down below the ground surface. It is configured to be accommodated in the formed concrete silo 106 with an interval. Further, in the liquid metal cooled nuclear reactor 100 having such a configuration, in order to cope with an emergency situation during the operation of the nuclear reactor or to perform a maintenance service, it is necessary to stop the nuclear fission reaction and bring it to a cold shutdown state. . In such a case, the reactor operation is generally stopped by inserting the neutron absorption control device 107 into the core 103 and taking away neutrons necessary for causing fission.

  However, even after the shutdown operation is performed, the residual decay heat continues to be generated from the nuclear fuel core 103 for a certain period of time, so the temperature of the liquid metal coolant 101 in the reactor vessel 102 does not decrease. Therefore, this residual decay heat must be dissipated as quickly as possible in order to perform any work after the stop. The heat of the core 103 is transmitted by heat radiation from the liquid metal coolant 101 having a large heat capacity to the reactor vessel 102 and further to the containment vessel 105, the temperature of the containment vessel 105 rises, and the heat of the containment vessel 105 is increased outside. Radiated toward a structure such as a concrete silo 106.

  However, when a structure such as a silo 106 made of concrete is exposed to a high temperature for a long period of time, its properties change and it tends to become brittle. For example, the silo 106 can be expected to expand and crack. Further, it is conceivable that the reactor vessel 102 made of stainless steel has a reduced strength when exposed to an excessively high temperature for a long time. For this reason, in order to remove heat from the containment vessel 105, air is circulated as a working fluid in the gap 108 between the containment vessel 105 and the silo 106, and natural convection, heat conduction, and heat radiation are completely passive. A passive cooling system (RVACS: Reactor Vessel Auxiliary Cooling System) (Reactor Vessel Auxiliary Cooling System) 109 that is continuously operated in the process is provided so as to cope with it.

  Since the passive cooling system 109 performs natural heat convection of the working fluid air 110 to remove heat, the air cooling passage 111 for allowing the air 110 to descend and rise outside the storage container 105 is provided with the storage container 105 and the silo. A cylindrical heat collector 112 is provided in the gap 108 between the two.

  The gas cooling flow path 111 includes a downflow passage 113 in which the low-temperature air 110C formed between the silo 106 and the heat collector 112 descends, and a high-temperature air 110H formed between the heat collector 112 and the outer wall of the storage container 105. It has the upflow passage 114 which rises. Air 110H heated to a high temperature by the heat of the containment vessel 105 rises in the upward flow passage 114, flows through the discharge pipe 115, and passes through the air discharge port 116 provided in the vicinity of the silo 106 in which the containment vessel 105 is accommodated. To be released.

  As a result, external air 110 is taken into the downflow passage 113 from the air intake port 117, and the low-temperature air 110 C thus taken flows down the downflow passage 113 from the intake pipe 118. The flow direction is changed in the bottom space to flow into the upward flow path 114 and heated while flowing upward along the outer wall of the storage container 105 to release the heat of the storage container 105 to the outside. In addition, 119 is a reflector, 120 is an electromagnetic pump, 121 is an intermediate heat exchanger (IHX), and 122 is a storage dome that covers the top.

  In addition, the passive cooling system 109 has an air 110 caused by a difference in density due to a temperature difference between the low-temperature air 110 </ b> C introduced from the outside that changes about 40 ° C. to −40 ° C. depending on the season and the air 110 </ b> H heated by the heat of the reactor vessel 102. Therefore, if the temperature difference between the low-temperature air 110C and the high-temperature air 110H is large, the circulation flow rate of the air 110 increases, which is preferable for removing residual decay heat. During operation, the amount of heat removed by the passive cooling system 109 is increased, and the power generation efficiency of the nuclear reactor is reduced.

  In addition, in such a passive cooling system, a passive heat removal system, which is a reactor vessel auxiliary cooling system of a liquid metal cooling reactor, is separated from each other as a baffle in a gap between a containment vessel and a silo. There is a structure in which a heat collecting outer wall of a hole and a heat collecting inner wall of a hole are provided to promote the removal of decay heat (see, for example, Patent Document 1), and a containment vessel of a pressurized water reactor As a passive cooling device, an air fluid is provided between the containment vessel and the shielding building to be housed to form first and second annular spaces inside and outside, and external air is allowed to flow through both annular spaces by natural circulation by heating. However, cooling is performed by flowing water from the water supply source to the upper center of the containment vessel, and discharging the generated water vapor from the chimney-shaped cylinder above the containment vessel (see, for example, Patent Document 2). There is.

Japanese Patent No. 3499920 Japanese Patent No. 2813412

  As described above, in a liquid metal cooled nuclear reactor or the like, a passive cooling system is configured by natural circulation of air generated by a temperature difference between low-temperature air from the outside and high-temperature air heated by the heat of the reactor vessel. In the event of a fire, such as an aircraft crashing near the reactor building and causing flames, the ambient air temperature rises and becomes hot, so if there is an air intake for the passive cooling system near the reactor building, May not be able to be taken in, and the passive cooling function may not be ensured.

  The present invention has been made in view of such circumstances, and the purpose of the present invention is to make the passive cooling function normal even if the air temperature in the vicinity of the reactor building rises due to, for example, a fire caused by an aircraft crash, etc. It is to provide a passive cooling system for a liquid metal cooled nuclear reactor that can be maintained.

  The present invention achieves the above object, and a cylindrical heat collector is provided between a containment vessel for storing a nuclear reactor vessel and a silo for containing the containment vessel, and the heat collector and the silo A downflow passage is formed as a gas cooling passage, and an upflow passage is formed between the heat collector and the outer wall of the containment vessel, and external air is introduced into the downflow passage through an air intake and intake pipe. The air flow is changed from a downward flow to an upward flow at the bottom of the silo and circulated through the upward flow passage, and then cooled to the outside through a discharge pipe and an air discharge port. A passive cooling system for a liquid metal cooled nuclear reactor, wherein a plurality of the air intake portions are provided with a gap of a predetermined separation distance or more between them, and are also provided apart from the air discharge port. And a separation distance between the air intake portion and the containment container is not less than a predetermined distance that is not easily affected by an aircraft accident in the vicinity of the containment container. is there.

  According to the present invention, even when the air temperature near the reactor building rises due to an accident or the like around the reactor building, the passive cooling function can be maintained normally.

1 is a longitudinal sectional view of a liquid metal cooled nuclear reactor in a first embodiment of the present invention. It is a cross-sectional view in the AA line of the liquid metal cooling reactor shown in FIG. It is a cross-sectional view in the BB line of the liquid metal cooling nuclear reactor shown in FIG. It is a longitudinal cross-sectional view of the liquid metal cooling nuclear reactor in the modification of the 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the principal part of the liquid metal cooling nuclear reactor in the 2nd Embodiment of this invention. It is a longitudinal cross-sectional view of the principal part of the liquid metal cooling nuclear reactor in the 3rd Embodiment of this invention. It is a longitudinal cross-sectional view of the principal part of the liquid metal cooling nuclear reactor in the 4th Embodiment of this invention. It is a longitudinal cross-sectional view of the principal part of the liquid metal cooling nuclear reactor in the 5th Embodiment of this invention. It is a longitudinal cross-sectional view of the principal part of the liquid metal cooling nuclear reactor in the 6th Embodiment of this invention. It is a longitudinal cross-sectional view which shows the conventional liquid metal cooling nuclear reactor.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the part same as the past, description is abbreviate | omitted, and the structure of embodiment of this invention different from the past is demonstrated.

(First embodiment)
First, a first embodiment of the present invention will be described with reference to FIGS. A modification in the present embodiment will be described with reference to FIG.

  As shown in FIGS. 1 to 3, in the liquid metal cooled nuclear reactor 1 of the first embodiment, the core 103 is submerged in the liquid metal coolant 101 in the nuclear reactor vessel 102, and the nuclear reactor vessel 102 is stored in the containment vessel 105. And is housed in a concrete silo 106. A gas cooling passage 111 of the passive cooling system 2 is formed in the annular gap 108 between the containment vessel 105 and the silo 106 by providing a cylindrical heat collector 112, and a working fluid gas such as air 110 is introduced from the outside into the annular downward flow passage 113 between the silo 106 and the heat collector 112, flows in the downward direction, changes the flow direction in the bottom space of the silo 106 below the lower end of the heat collector 112, and It flows in the upward direction through the annular upward flow passage 114 between the outer walls of the storage container 105 and is discharged to the outside.

  An annular intake header 3 and discharge header 4 are provided concentrically below the ground surface around the top of the silo 106 so that the intake header 3 is on the upper side. The intake-side header 3 communicates with the upper part of the downflow passage 113 of the gas cooling channel 111 through a plurality of intake-side communication tubes 5, and the discharge-side header 4 communicates with the gas cooling channel through a plurality of discharge-side communication tubes 6. 111 communicates with the upper part of the upward flow passage 114.

  Further, the intake-side header 3 is connected to the other end of a plurality of intake pipes 8 that are radially embedded below the surface of the ground having an air intake portion 7 at each tip, for example, a length of 50 m or more. ing. The air intake portion 7 provided at the tip of each intake pipe 8 includes an air intake port 9 and a melting valve 10 that operates and closes at a predetermined temperature or higher, so that the melting valve 10 is positioned in the vicinity of the air intake port 9. Both are installed so as to be exposed on the ground surface. On the other hand, the discharge-side header 4 is shorter than the intake pipe 8 and has a radial shape below the surface of the earth so that the air discharge ports 116 are provided at the respective end portions so as to be exposed on the ground surface separated from the air intake port 9. The other ends of the plurality of discharge pipes 115 embedded in the are connected.

  Thereby, each air intake port 9 is opened with a predetermined distance from each other at a position sufficiently away from the reactor building that houses the containment vessel 105, and the air discharge port 116 is an air intake port relatively close to the containment vessel 105. 9 is opened at a different position. 2 and 3, which show cross sections taken along lines AA and BB in FIG. 1, the reactor core 103, the neutron absorption control device 107, and the electromagnetic pump 120 stored in the reactor vessel 102. Etc. are omitted (the same applies to the following drawings).

  In the liquid metal cooled nuclear reactor 1 configured as described above, for example, the neutron absorption control device 107 is inserted into the core 103 to stop the reactor operation, and the core 103 generated even after the operation is stopped. The residual decay heat is transferred from the liquid metal coolant 101 to the reactor vessel 102 and further to the containment vessel 105 by heat radiation, the temperature of the containment vessel 105 rises, and the heat of the containment vessel 105 is further transferred by the passive cooling system 2. Released to the outside.

  The release of heat to the outside by the passive cooling system 2 causes the high-temperature air 110H heated by the containment vessel 105 to rise in the upward flow path 114 along the outer wall of the containment vessel 105 of the gas cooling passage 111, and the discharge pipe 115, which is performed by being sent out from the air discharge port 116. Moreover, natural convection occurs when the high-temperature air 110 </ b> H flows through the upflow passage 114, and external low-temperature air 110 </ b> C is introduced into the downflow passage 113 along the inner wall of the silo 106 through the air intake port 9 and the intake pipe 8. Then, the heat release to the outside through the air 110 continues.

  In such a liquid metal cooled nuclear reactor 1, the nuclear fuel core 103 is normally submerged in the liquid metal coolant 101 filled up to the normal liquid level in the reactor vessel 102. The heat generated by the nuclear fission is taken out by circulating the liquid metal coolant 101 and used for power generation or the like. During operation, the containment vessel 105 is also heated due to heat generated by fission, and cooling is always performed by the air 110 flowing through the gas cooling flow path 111 of the passive cooling system 2.

  In addition, when an aircraft or the like crashes near the reactor building in which the containment vessel 105 is stored, and the flame rises, the ambient temperature of the reactor building becomes high. However, the temperature around the air intake portion 7 provided at a predetermined distance or more away from the silo 106 containing the storage container 105 sufficiently far away, for example, 50 m or more, and not easily affected by heat such as a crash. Does not reach a high temperature, and the melting valve 10 does not close. In addition, since the temperature of the external air 110 introduced from the air intake 7 to the downflow passage 113 of the gas cooling passage 111 via the intake header 3 is not high, the passive cooling system 2 also functions, and the reactor The residual decay heat of the core 103 generated after the operation is stopped can also be reliably removed, and the liquid metal cooling reactor 1 can be brought into a low temperature stop state without requiring a long time.

  For example, when the crash location of an aircraft or the like is near the air intake portion 7, among the air intake portions 7 provided so as to be separated from each other, the ambient temperature of the air intake portion 7 near the crash location is High temperature. As a result, the melting valve 10 of the air intake portion 7 near the falling place is closed, and the external air 110 is not taken in from the air intake port 9. However, since the other air intake parts 7 are spaced apart so that at least one air intake part 7 functions without being affected by a crash or the like, the ambient temperature does not become a high temperature, Since the temperature of the external air 110 introduced from the air intake 9 into the downflow passage 113 of the gas cooling passage 111 is not high, the passive cooling system 2 also functions, and in this case, it occurs after the reactor operation is stopped. The residual decay heat of the core 103 can be reliably removed, and the liquid metal cooled nuclear reactor 1 can be brought into a cold shutdown state without requiring a long time.

  Furthermore, for example, when a crash location such as an airplane is near the air discharge port 116, the ambient temperature of the air discharge port 116 is high, and an upward flow is generated due to an increase in the air temperature near the crash location. . As the upward flow is generated, the air around the air outlet 116 is also raised, and the high-temperature air 110H heated by the storage container 105 and discharged from the air outlet 116 is also accompanied by the acceleration. Therefore, the air circulation amount of the passive cooling system 2 is increased, and the cooling function can be sufficiently secured.

  As described above, according to the present embodiment, the passive cooling system 2 functions normally even when a fire such as an aircraft crashes and flames occur near the air intake 9 or the air outlet 116. Thus, it is possible to reliably remove the residual decay heat generated after the nuclear reactor operation is stopped, and the liquid metal cooled nuclear reactor 1 can be brought into a low temperature shutdown state without requiring a long time.

  In the present embodiment, the discharge pipe 115 has a short size and the air discharge port 116 is provided in the vicinity of the silo 106 in which the storage container 105 is accommodated. However, the discharge pipe 11 has a modification as shown in FIG. May be configured in a long dimension.

  That is, as shown in FIG. 4, the passive cooling system 2a of the liquid metal cooling reactor 1a has a plurality of discharges having a relatively long dimension that is the same length as, for example, the intake pipe 8 or a shorter dimension. The piping 11 is provided so as to protrude radially from the discharge side header 4. The discharge pipe 11 is buried below the ground surface in the same manner as the intake pipe 8, and an air discharge port 116 is separated from the silo 106 in which the storage container 105 is accommodated at each tip portion, and also from the air intake port 9. It is provided so as to be exposed at a position on the ground surface that is spaced apart.

  As a result, the air intake 9 and the air outlet 116 are sufficiently separated from the reactor building or the like that stores the containment vessel 105, and the air intake 9 and the air outlet 116 are opened at different positions sufficiently separated from each other. become.

  With such a configuration, the air intake ports 9 and the air discharge ports 116 of the passive cooling system 2a are dispersedly arranged. For example, when an aircraft or the like crashes and burns, one air discharge port 116 is left by the aircraft debris. Even if it is blocked, the passive cooling function can be ensured, and the influence accompanying the occurrence of the accident can be minimized, and the same effect as the above-described embodiment can be obtained. be able to.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, since this embodiment differs from 1st Embodiment only in the structure of a heat collector, it demonstrates focusing on a different part.

  As shown in FIG. 5, in the liquid metal cooling nuclear reactor 21 of the second embodiment, the heat collector 23 constituting the passive cooling system 22 is formed by a cylindrical hollow wall. For example, a plurality of hollow members 25 having the same size or different sizes in a spherical shape are filled. The hollow member 25 is in a state where, for example, air or a gas such as argon, krypton, or xenon having low thermal conductivity is sealed in the hollow, or in a vacuum state in which the hollow is decompressed to a predetermined pressure. Yes.

  In the liquid metal cooled nuclear reactor 21 configured as described above, when, for example, the neutron absorption control device 107 is inserted into the core 103 and the reactor operation is stopped, as in the first embodiment described above, Residual decay heat generated after the shutdown is transferred from the liquid metal coolant 101 to the reactor vessel 102 and further to the containment vessel 105 by heat radiation, and the transferred heat of the containment vessel 105 is released to the outside by the passive cooling system 22. Is done.

  The release of heat to the outside by the passive cooling system 22 causes the high-temperature air 110H heated by the containment vessel 105 to rise in the upward flow path 114 along the outer wall of the containment vessel 105 of the gas cooling flow path 111, and the air is discharged. This is done by being sent out from the outlet 116. In addition, natural convection occurs when the air 110 is heated and flows through the upward flow passage 114, and low-temperature air 110 C from the outside is introduced into the downward flow passage 113 along the inner wall of the silo 106 through the air intake port 9 and the intake pipe 8. Then, the heat release to the outside through the air 110 continues.

  When heat is released to the outside by the passive cooling system 22, heat is transferred from the outer wall surface of the storage container 105 to the wall surface of the heat collector 23 facing the outer wall of the storage container 105 by radiation. The transferred heat is transferred through the heat collector 23 to the wall surface facing the inner wall of the silo 106 by heat conduction. However, since the hollow part 24 of the heat collector 23 is filled with a plurality of hollow members 25 and the heat passage resistance is high, the temperature rise of the wall surface of the heat collector 23 facing the inner wall of the silo 106 is suppressed, and the wall surface temperature is reduced. It can be kept at a low temperature.

  And radiation to the inner wall surface of the silo 106 facing the heat collector 23 is suppressed, and the wall surface temperature of the inner wall of the silo 106 can be kept at a low temperature. As a result, the low-temperature air 110C introduced from the outside through the air intake 9 and the intake pipe 8 flows into the upward flow passage 114 along the outer wall of the containment vessel 105 at a low temperature. Therefore, a large temperature difference from the outer wall of the containment vessel 105 heated by the heat can be obtained.

  As described above, according to the present embodiment, similar to the first embodiment, the residual decay heat generated after the reactor operation is stopped can be reliably removed, and the low-temperature air 110C flowing into the upward flow passage 114 can be removed. And the high temperature air 110H can be increased, higher heat removal capability can be obtained, and the liquid metal cooling reactor 21 can be brought into a cold shutdown state without requiring a long time.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. In addition, since this embodiment differs from 1st Embodiment only in the structure of a heat collector, it demonstrates focusing on a different part.

  As shown in FIG. 6, in the liquid metal cooling nuclear reactor 31 of the third embodiment, the heat collector 33 constituting the passive cooling system 32 is formed by a cylindrical hollow wall. A gas 35 having a lower thermal conductivity than air, such as argon, krypton, or xenon, is filled at a predetermined pressure, so that the heat transfer efficiency is lowered.

  In the liquid metal cooled nuclear reactor 31 configured as described above, when the reactor operation is stopped by inserting the neutron absorption control device 107 into the core 103, for example, as in the first embodiment described above, Residual decay heat generated after the shutdown is transferred from the liquid metal coolant 101 to the reactor vessel 102 and further to the containment vessel 105 by heat radiation, and the transferred heat of the containment vessel 105 is released to the outside by the passive cooling system 32. Is done.

  The release of heat to the outside by the passive cooling system 32 causes the high-temperature air 110H heated by the containment vessel 105 to rise in the upward flow path 114 along the outer wall of the containment vessel 105 of the gas cooling flow path 111, and the air is discharged. This is done by being sent out from the outlet 116. In addition, natural convection occurs when the air 110 is heated and flows through the upward flow passage 114, and low-temperature air 110 C from the outside is introduced into the downward flow passage 113 along the inner wall of the silo 106 through the air intake port 9 and the intake pipe 8. Then, the heat release to the outside through the air 110 continues.

  When heat is released to the outside by the passive cooling system 32, heat is transferred from the outer wall surface of the storage container 105 to the wall surface of the heat collector 33 facing the outer wall of the storage container 105 by radiation. The transferred heat is transferred to the wall surface side facing the inner wall of the silo 106 by heat conduction in the heat collector 33. However, since the hollow portion 34 of the heat collector 33 is filled with the gas 35 and the heat passage resistance is high, the temperature rise of the wall surface of the heat collector 33 facing the inner wall of the silo 106 is suppressed, and the wall surface temperature is lowered. Can be held.

  And radiation to the inner wall surface of the silo 106 facing the heat collector 33 is suppressed, and the wall surface temperature of the inner wall of the silo 106 can be kept at a low temperature. As a result, the low-temperature air 110C introduced from the outside through the air intake 9 and the intake pipe 8 flows into the upward flow passage 114 along the outer wall of the containment vessel 105 at a low temperature. Therefore, a large temperature difference from the outer wall of the containment vessel 105 heated by the heat can be obtained.

  As described above, according to the present embodiment, similar to the first embodiment, the residual decay heat generated after the reactor operation is stopped can be reliably removed, and the low-temperature air 110C flowing into the upward flow passage 114 can be removed. And the high-temperature air 110H can be increased, higher heat removal capability can be obtained, and the liquid metal cooling reactor 31 can be brought into a cold shutdown state without requiring a long time.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. In addition, since this embodiment differs from 1st Embodiment only in the structure of a heat collector, it demonstrates focusing on a different part.

  As shown in FIG. 7, in the liquid metal cooling nuclear reactor 41 of the fourth embodiment, the heat collector 43 constituting the passive cooling system 42 is formed by a cylindrical hollow wall, and the inside of the hollow portion 44 is The vacuum is reduced to a predetermined pressure.

  In the liquid metal cooled nuclear reactor 41 configured as described above, when the reactor operation is stopped by inserting the neutron absorption control device 107 into the core 103, for example, as in the first embodiment described above, The residual decay heat generated after the shutdown is transferred from the liquid metal coolant 101 to the reactor vessel 102 and further to the containment vessel 105 by heat radiation, and the transferred heat of the containment vessel 105 is released to the outside by the passive cooling system 42. Is done.

  The release of heat to the outside by the passive cooling system 42 causes the high-temperature air 110H heated by the containment vessel 105 to rise in the upward flow path 114 along the outer wall of the containment vessel 105 of the gas cooling flow path 111, and the air is discharged. This is done by being sent out from the outlet 116. In addition, natural convection occurs when the air 110 is heated and flows through the upward flow passage 114, and low-temperature air 110 C from the outside is introduced into the downward flow passage 113 along the inner wall of the silo 106 through the air intake port 9 and the intake pipe 8. Then, the heat release to the outside through the air 110 continues.

  When heat is released to the outside by the passive cooling system 42, heat is transferred from the outer wall surface of the storage container 105 to the wall surface of the heat collector 43 that faces the outer wall of the storage container 105 by radiation. The transferred heat is transferred through the heat collector 43 to the wall surface side facing the inner wall of the silo 106 by heat conduction. However, since the hollow portion 44 of the heat collector 43 is in a vacuum state where the pressure is reduced to a predetermined pressure and the heat passage resistance is high, the temperature rise of the wall surface of the heat collector 43 facing the inner wall of the silo 106 is suppressed, The wall surface temperature can be kept low.

  And radiation to the inner wall surface of the silo 106 facing the heat collector 43 is suppressed, and the wall surface temperature of the inner wall of the silo 106 can be kept at a low temperature. As a result, the low-temperature air 110C introduced from the outside through the air intake 9 and the intake pipe 8 flows into the upward flow passage 114 along the outer wall of the containment vessel 105 at a low temperature. Therefore, a large temperature difference from the outer wall of the containment vessel 105 heated by the heat can be obtained.

  As described above, according to the present embodiment, similar to the first embodiment, the residual decay heat generated after the reactor operation is stopped can be reliably removed, and the low-temperature air 110C flowing into the upward flow passage 114 can be removed. And the high temperature air 110H can be increased, higher heat removal capability can be obtained, and the liquid metal cooling reactor 41 can be brought into a low temperature shutdown state without requiring a long time.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described with reference to FIG. Since the present embodiment is different from the first embodiment only in the configuration of the heat collector, different portions will be mainly described.

  As shown in FIG. 8, the liquid metal cooling reactor 51 of the fifth embodiment includes a cylindrical heat collector 53 constituting a passive cooling system 52, and the downflow passage 113 is provided in the heat collector 53. A through hole 54 penetrating from the downflow passage 113 toward the upflow passage 114 at a predetermined interval in the circumferential direction is formed at a position that is an intermediate position of the throughflow passage. Corresponding to each through hole 54, an ejector 55 is provided in the upward flow passage 114, with the nozzle portion 55a on the upstream side in the air flow direction and the diffuser portion 55b on the downstream side, penetrating with the suction hole 55d of the throat portion 55c. It arrange | positions so that the hole 54 may connect, for example, is arrange | positioned above the storing position of the core 103. FIG.

  In the liquid metal cooled nuclear reactor 51 configured in this way, as in the first embodiment described above, the liquid metal coolant 101 filled in the reactor vessel 102 up to the normal liquid level position is normally stored. The nuclear fuel core 103 is submerged, and heat generated by nuclear fission in the nuclear fuel core 103 is extracted outside by circulating the liquid metal coolant 101 and used for power generation or the like. During operation, the containment vessel 105 is also heated due to heat generated by fission, and cooling is performed by the air 110 flowing through the gas cooling flow path 111 of the passive cooling system 52.

  When cooling is performed by circulating the air 110 through the gas cooling channel 111, for example, in the winter season, when the temperature of the external air is −40 ° C., the low-temperature air 110C is taken into the gas cooling channel 111 and the temperature is low. Of the air 110C flows down the downflow passage 113 at a low temperature. A part of the low-temperature air 110C flowing down is sucked by the ejector 55 provided at an intermediate position in the upward flow path 114 between the heat collector 53 and the storage container 105, and mixed with the high-temperature air 110H. The mixed air 110M having a temperature lower than that of the air 110H is sent to the downstream side of the upward flow passage 114 and circulates, and is discharged from the air discharge port 116 to the outside.

  As a result, the temperature difference between the low-temperature air 110C flowing down the downflow passage 113 and the mixed air 110M discharged through the upflow passage 114 is reduced, the air circulation flow rate is reduced, and power generation during normal operation is reduced. Reduction in efficiency can be suppressed.

  As described above, according to the present embodiment, similar to the first embodiment, the residual decay heat generated after the reactor operation is stopped can be surely removed, and taken in from the air intake 9 during normal operation. Even when the temperature of the air is low, the temperature difference from the air discharged from the air discharge port 116 can be reduced, and the decrease in power generation efficiency of the liquid metal cooled reactor 51 can be suppressed.

  In this embodiment, the heat collector 53 is not hollow. However, as shown in the second to fourth embodiments described above, although not shown, a hollow portion is formed in the heat collector 53, and a large number of them are formed in the hollow portion. It is possible to fill a single hollow member, fill a predetermined gas, or make the hollow portion in a vacuum state to increase the heat passage resistance and maintain the inner wall surface temperature of the silo 106 at a low temperature. Good.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described with reference to FIG. In addition, since this embodiment differs from 1st Embodiment only in the structure of a heat collector, it demonstrates focusing on a different part.

  As shown in FIG. 9, the liquid metal cooling nuclear reactor 61 of the sixth embodiment includes a cylindrical heat collector 63 that constitutes a passive cooling system 62, and the downflow passage 113 is provided in the heat collector 63. A communication hole 64 penetrating from the downflow passage 113 toward the upflow passage 114 at a predetermined interval in the circumferential direction is formed at a position above the storage position of the core 103, for example.

  In the liquid metal cooled nuclear reactor 61 configured in this way, as in the first embodiment described above, the liquid metal coolant 101 filled in the reactor vessel 102 up to the normal liquid level is normally stored. The nuclear fuel core 103 is submerged, and heat generated by nuclear fission in the nuclear fuel core 103 is extracted outside by circulating the liquid metal coolant 101 and used for power generation or the like. During operation, the containment vessel 105 is also heated due to heat generated by fission, and cooling is performed by the air 110 flowing through the gas cooling flow path 111 of the passive cooling system 62.

  When cooling is performed by circulating the air 110 through the gas cooling channel 111, for example, in the winter season, when the temperature of the external air is −40 ° C., the low-temperature air 110C is taken into the gas cooling channel 111 and the temperature is low. Of the air 110C flows down the downflow passage 113 at a low temperature. Part of the low-temperature air 110C that flows down flows into the upward flow passage 114 between the heat collector 63 and the storage container 105 from the communication hole 64 formed in the heat collector 63, and the high-temperature air that flows through the upward flow passage 114. 110H is mixed, and the mixed air 110M having a temperature lower than that of the high-temperature air 110H flows through the upward flow passage 114 on the downstream side of the communication hole 64 formation position and is discharged to the outside from the air discharge port 116.

  As a result, the temperature difference between the low-temperature air 110C flowing down the downflow passage 113 and the mixed air 110M discharged through the upflow passage 114 is reduced, the air circulation flow rate is reduced, and power generation during normal operation is reduced. Reduction in efficiency can be suppressed.

  As described above, according to the present embodiment, similar to the first embodiment, the residual decay heat generated after the reactor operation is stopped can be surely removed, and taken in from the air intake 9 during normal operation. Even when the temperature of the air is low, the temperature difference from the air discharged from the air discharge port 116 can be reduced, and the decrease in power generation efficiency of the liquid metal cooled reactor 61 can be suppressed.

  In this embodiment, the heat collector 63 is not hollow. However, as shown in the second to fourth embodiments described above, although not shown, a hollow portion is formed in the heat collector 63, and a large number of them are formed in the hollow portion. It is possible to fill a single hollow member, fill a predetermined gas, or make the hollow portion in a vacuum state to increase the heat passage resistance and maintain the inner wall surface temperature of the silo 106 at a low temperature. Good.

1, 1a, 21, 31, 41, 51, 61 ... liquid metal cooling reactor, 2, 2a, 22, 32, 42, 52, 62 ... passive cooling system, 3 ... intake header, 4 ... discharge header, DESCRIPTION OF SYMBOLS 5 ... Intake side communication pipe, 6 ... Discharge side communication pipe, 7 ... Air intake part, 8 ... Intake pipe, 9 ... Air intake port, 10 ... Melting valve, 11, 115 ... Discharge pipe, 23, 33, 43, 53 , 63, 112 ... heat collector, 24, 34, 44 ... hollow part, 25 ... hollow member, 35 ... gas, 54 ... through hole, 55 ... ejector, 55a ... nozzle part, 55b ... diffuser part, 55c ... throat part, 55d ... Suction hole, 64 ... Communication hole, 101 ... Liquid coolant, 102 ... Reactor vessel, 103 ... Core, 104 ... Gap, 105 ... Containment vessel, 106 ... Silo, 107 ... Neutron absorption control device, 108 ... Gap, 110 ... Air, 110C ... low temperature air, 110H ... high temperature air, 110M ... mixed air, 111 ... gas cooling flow path, 113 ... downflow path, 114 ... upflow path, 116 ... discharge port, 119 ... reflector, 120 ... Electromagnetic pump 121 ... IHX 122 ... Storage dome

Claims (7)

A cylindrical heat collector is provided between a containment vessel for storing the reactor vessel and a silo for containing the containment vessel, and a downflow passage as a gas cooling channel between the heat collector and the silo, the heat An upflow passage is formed between the collector and the outer wall of the containment vessel, and external air is introduced into the downflow passage via an air intake and intake pipe, and the air flow is lowered at the bottom of the silo. It is a passive cooling system for a liquid metal cooling nuclear reactor that cools by changing the flow from an upward flow to an upward flow and then circulated through the upward flow passage and then discharging it through an exhaust pipe and an air discharge port.
A plurality of the air intake portions are provided with a gap of a predetermined separation distance or more between them, and are arranged so as to be separated from the air discharge port, and the air intake portion and the storage are provided. A passive cooling system for a liquid metal-cooled nuclear reactor, wherein a separation distance from the vessel is not less than a predetermined distance that is not easily affected by an aircraft accident or the like in the vicinity of the containment vessel.   2. The air intake section according to claim 1, wherein the air intake portion includes an air intake opening and a melting valve, and the melting valve is provided so as to be exposed on a ground surface in the vicinity of the air intake opening. Passive cooling system for liquid metal cooled reactors.   3. The passive cooling system for a liquid metal cooled nuclear reactor according to claim 1, wherein the heat collector is formed in a hollow shape, and a plurality of hollow members are filled in the hollow space.   3. The passive cooling system for a liquid metal cooled nuclear reactor according to claim 1, wherein the heat collector is formed in a hollow shape, and a predetermined gas is filled in the hollow.   3. The passive cooling system for a liquid metal cooled nuclear reactor according to claim 1, wherein the heat collector is formed in a hollow shape, and the hollow interior is maintained at a predetermined degree of vacuum.   A part of the air flowing down the downflow passage intermediate portion is sucked into the intermediate portion of the upflow passage between the heat collector and the containment vessel, and mixed with the air flowing through the upflow passage. 6. The passive cooling system for a liquid metal cooled nuclear reactor according to claim 1, wherein an ejector is provided.   6. The liquid according to claim 1, wherein a communication hole is formed in the heat collector to connect the intermediate portion of the downflow passage and the intermediate portion of the upflow passage. Passive cooling system for metal-cooled nuclear reactors.

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