JP2013076675A - Passive cooling system for liquid metal cooling reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve sufficient heat removal when removing residual decay heat generated in a reactor core.SOLUTION: In a passive cooling system 32 for a liquid metal cooling reactor, a downflow passage 35 is formed between a heat collector 34 and a silo 31, an upflow passage 36 is formed between the heat collector 34 and a guard vessel 19, a cooling passage 33 is configured by including the passages 35 and 36, and during a period in which external air is introduced into the downflow passage 35 and is allowed to flow down, an air flow is converted into an upflow on the bottom of the silo 31 and then is allowed to flow up in the upflow passage 36 and is exhausted to the external, a liquid metal cooling material 13, a reactor vessel 11 and the guard vessel 19 are cooled. In the passive cooling system 32, a heat absorption member 41 is arranged on the upper part of the inside of the reactor vessel 11 in a state immersed in a liquid metal cooling material 13 and a heat sink 42 is arranged on the upper part of the reactor vessel 11 so as to be thermally connected to or isolated from the heat absorption member 41. In thermal connection with the heat absorption member 41, the heat sink 42 discharges heat of the heat absorption member 41 to the outside of the reactor vessel.

Description

  The present invention relates to a passive cooling system for a liquid metal cooled nuclear reactor that removes residual decay heat generated in the core when the reactor is shut down in a liquid metal cooled nuclear reactor.

  In the liquid metal cooled nuclear reactor 100 as shown in FIG. 11, the nuclear fission reaction in the core 101 is stopped in order to cope with an emergency situation during operation or to perform maintenance and inspection, resulting in a cold shutdown state. You may have to. In general, the reactor is shut down by inserting a neutron absorption control device 102 into the core 101 and depriving the fuel of neutrons necessary for fission. However, since the residual decay heat continues to be generated from the core 101 for a certain period of time after the reactor is shut down, the temperature of the liquid metal coolant 104 in the reactor vessel 103 does not decrease rapidly. Therefore, it is necessary to dissipate this residual decay heat from the core 101 as soon as possible in order to perform some work after the reactor is shut down.

  By the way, since the liquid metal coolant 104 and the adjacent nuclear reactor structural materials (reactor vessel 103, guard vessel 105, etc.) have a large heat capacity, dissipation of residual decay heat is hindered. For example, the residual decay heat accumulated in the liquid metal coolant 104 is transmitted from the reactor vessel 103 to the guard vessel 105, and the heat of the guard vessel 105 is also arranged separately from the guard vessel 105 and separated from the silo 106. As a result, the temperature of the reactor vessel 103, the guard vessel 105, and the concrete structure 107 rises.

  However, when the concrete structure 107 is exposed to a high temperature for a long period of time, its properties tend to change and become brittle. For example, when the concrete structure 107 is exposed to a high temperature, it may expand and crack. In addition, the reactor vessel 103 that is generally made of SUS may be reduced in strength when exposed to an excessively high temperature for a long time.

  Therefore, in order to prevent overheating of the nuclear reactor structural material due to residual decay heat, a system called decay heat removal system is generally adopted. This decay heat removal system has a fully passive passive cooling system (RVACS) 108 that uses air as the working fluid and operates continuously through the inherent processes of natural convection, heat conduction, and heat radiation. There is a thing (refer patent document 1). In FIG. 11, reference numeral 111 denotes a reflector, 112 denotes an electromagnetic pump, and 113 denotes an intermediate heat exchanger.

  In this passive cooling system (RVACS) 108, heat generated in the core 101 during normal operation and residual decay heat generated in the core 101 when the reactor is shut down are first transferred from the liquid metal coolant 104 to the reactor vessel 103. The Next, the heat of the reactor vessel 103 is transmitted to the guard vessel 105 by thermal radiation, and also by heat conduction or natural convection by an inert gas filled in the gap between the reactor vessel 103 and the guard vessel 105. , Transmitted to the guard vessel 105. Next, the heat of the guard vessel 105 is heated by heat radiation between the outer surface of the guard vessel 105 and the heat collector 109 installed to form the air passage 110 in the passive cooling system (RVACS) 108. In addition to being transmitted to the collector 9, it is transmitted to the air in the air passage 110 by natural convection in the air passage 110. Further, the heat of the heat collector 109 is transferred to the concrete structure 107 by heat radiation, and the heat of the heat collector 109 and the concrete structure 107 is air in the air passage 110 by natural convection in the air passage 110. Is transmitted to.

JP 2011-21901 A

  However, when the residual decay heat generated in the core 101 is removed using the passive cooling system 108 as described above, the gas (for example, inert gas) filled in the gap between the reactor vessel 103 and the guard vessel 105 is removed. Since the thermal conductivity of the gas) is low, this gas becomes a thermal resistance when removing the residual decay heat.

  An object of the present invention is to provide a passive cooling system for a liquid metal cooled nuclear reactor, which has been made in consideration of the above-described circumstances and has improved the heat removal performance of residual decay heat generated in the core.

  A passive cooling system for a liquid metal cooled nuclear reactor according to an embodiment of the present invention has an endothermic arrangement in which at least a part of the passive cooling system is immersed in the liquid metal coolant at an upper part of a reactor vessel in which the liquid metal coolant is accommodated. A heat absorbing member supporting means for supporting the heat absorbing member and extending above the reactor vessel; a heat sink disposed above the heat absorbing member supporting means; and the heat sink holding means for holding the heat sink. The heat sink is dropped when the holding by the heat sink holding means is released, and is thermally connected to the heat absorbing member via the heat absorbing member supporting means.

  According to the embodiment of the present invention, the heat removal performance of the core can be improved.

1 is a schematic half-sectional view showing a liquid metal cooled nuclear reactor to which a first embodiment of a passive cooling system for a liquid metal cooled nuclear reactor according to the present invention is applied. The perspective view which shows the heat absorption member of FIG. 1, a heat sink, etc. FIG. The electromagnetic binding ring of FIG. 2 is shown, (A) is a closed state, (B) is a schematic plan view which shows an open state, respectively. The perspective view which shows the thermal absorption member in the 2nd Embodiment of the passive cooling system for liquid metal cooling reactors which concerns on this invention, a heat sink, and a cooling device. The sectional side view which shows the liquid metal cooling nuclear reactor to which 3rd Embodiment of the passive cooling system for liquid metal cooling nuclear reactors concerning this invention was applied. The sectional side view which shows the liquid metal cooling reactor to which 4th Embodiment of the passive cooling system for liquid metal cooling reactors which concerns on this invention was applied. The sectional side view which shows the liquid metal cooling reactor to which 5th Embodiment of the passive cooling system for liquid metal cooling reactors which concerns on this invention was applied. The sectional side view which shows the liquid metal cooling reactor to which 6th Embodiment of the passive cooling system for liquid metal cooling reactors which concerns on this invention was applied. The sectional side view which shows the liquid metal cooling reactor to which 7th Embodiment of the passive cooling system for liquid metal cooling reactors which concerns on this invention was applied. The sectional side view which shows the liquid metal cooling reactor to which 8th Embodiment of the passive cooling system for liquid metal cooling reactors which concerns on this invention was applied. The side sectional view showing the conventional liquid metal cooling nuclear reactor.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
[A] First embodiment (FIGS. 1 and 2)
FIG. 1 is a schematic half sectional view showing a liquid metal cooled nuclear reactor to which a first embodiment of a passive cooling system for a liquid metal cooled nuclear reactor according to the present invention is applied.

  In the liquid metal cooled nuclear reactor 10 shown in FIG. 1, a core 12 is disposed in a reactor vessel 11, and a liquid metal coolant (for example, liquid sodium) 13 as a primary coolant is filled and accommodated. . Accordingly, the core 12 is immersed in the liquid metal coolant 13. The core 12 is formed by arranging fuel assemblies (not shown) of nuclear fuel, and has a cylindrical shape as a whole.

  A cylindrical partition wall 14 is installed outside the core 12 so as to extend from a core support plate 15 that supports the core 12. Between the partition wall 14 and the core 12, an annular reflector 16 is disposed as a whole. A flow path 17 of the liquid metal coolant 13 is formed in an annular shape between the partition wall 14 and the reactor vessel 11, and the neutron shield supported by the core support plate 15 in the flow path 17. 18 is arranged. The neutron shield 18 shields neutrons radiated from the core 12 through the reflector 16 or bypassed. Further, a guard vessel 19 is provided outside the reactor vessel 11, and the reactor vessel 11 is stored and protected. A gap 26 between the reactor vessel 11 and the guard vessel 19 is filled with a gas such as an inert gas.

  In the reactor vessel 11, an annular electromagnetic pump 20 is disposed above the neutron shield 18, and an intermediate heat exchanger 21 is installed above the electromagnetic pump 20. The electromagnetic pump 20 and the intermediate heat exchanger 21 are integrally formed, for example. The electromagnetic pump 20 causes the liquid metal coolant 13 in the reactor vessel 11 to flow from the upper side to the lower side in the flow path 17 as indicated by the solid arrow A. Further, the liquid metal coolant 13 and the secondary coolant 25 flow on the tube side and the shell side of the intermediate heat exchanger 21, respectively.

  The reflector 16 is driven by a reflector drive mechanism 23 via a drive shaft 22 so as to be movable in the axial direction of the core 12, that is, in the vertical direction of the liquid metal cooling reactor 10. The drive shaft 22 is connected to the reflector 16 via a joint (not shown) and extends in the vertical direction of the reactor vessel 11 through an upper plug 24 that closes the upper portion of the reactor vessel 11. The reflector driving mechanism 23 is installed on the upper plug 24. The reflector 16 moves in the vertical direction of the liquid metal cooled reactor 10 to adjust the leakage of neutrons from the core 12 and control the reactivity of the core 12.

  By the operation of the liquid metal cooled reactor 10, the liquid metal coolant 13 in the reactor vessel 11 cools the core 12 and takes out heat generated by nuclear fission of the core 12 to the outside. As indicated by the solid arrow A, the liquid metal coolant 13 flows downward in the flow path 17 by the electromagnetic pump 20, flows in the neutron shield 18, and reaches the bottom of the reactor vessel 11. The liquid metal coolant 13 reaches the core 12 from the bottom of the reactor vessel 11, moves upward in the core 12 as indicated by an arrow B, the temperature rises, and the tube of the intermediate heat exchanger 21. Flows into the side. In the intermediate heat exchanger 21, the liquid metal coolant 13 exchanges heat with the secondary coolant 25, and then again flows downward in the flow path 17 by the electromagnetic pump 20.

  The secondary coolant 25 flows into the shell side of the intermediate heat exchanger 21 through the inlet nozzle 27 and is heated by the liquid metal coolant 13 flowing on the tube side of the intermediate heat exchanger 20, and then from the outlet nozzle 28. It flows out to the outside, and its heat is converted into power using a turbine or the like. 1 is a neutron absorption control device, and this neutron absorption control device 29 is driven by a neutron absorption control device drive mechanism 30 installed in the upper plug 24.

  In the liquid metal cooled nuclear reactor 10 as described above, the guard vessel 19 is accommodated and installed at intervals in a concrete silo 31 formed by digging under the ground surface. In this space between the guard vessel 19 and the silo 31, a completely passive passive cooling system (RVACS: Reactor) is operated continuously by a natural process of natural convection, heat conduction and heat radiation using air as a working fluid. A cooling passage 33 of a Vessel Auxiliary Cooling System) 32 is formed.

  That is, the cylindrical heat collector 34 is installed between the guard vessel 19 and the silo 31. A downward flow path 35 is formed between the heat collector 34 and the silo 31, and an upward flow path 36 is formed between the heat collector 34 and the guard vessel 19. The downward flow passage 35 is connected to an air introduction pipe 37 as an intake passage which is buried below the ground surface and includes an air introduction port 38. The upward flow passage 36 is connected to an air discharge pipe 39 as an exhaust passage embedded under the ground surface and provided with an air discharge port 40. The downflow passage 35, the upflow passage 36, the air introduction pipe 37 and the air discharge pipe 39 constitute a cooling passage 33.

  In the upward flow passage 36, the high-temperature air heated by the guard vessel 19 rises as indicated by an arrow Y, passes through the air discharge pipe 39, and is discharged to the outside from the air discharge port 40. Due to the air flow in the upflow passage 36, external low-temperature air is introduced into the downflow passage 35 through the air introduction port 38 and the air introduction pipe 37, and flows down (down) as indicated by an arrow X. . The air that has flowed down in the downflow passage 35 changes the flow to the upward flow at the bottom of the silo 31 below the end of the heat collector 34, and ascends in the upward flow passage 36 as described above. Discharged. While the air flows through the downflow passage 35 and the upflow passage 36, the liquid metal coolant 13, the reactor vessel 11, the guard vessel 19, and the concrete structure 31A forming the silo 31 are cooled.

  The heat generated in the core 12 during normal operation of the nuclear reactor and the residual decay heat generated in the core 12 when the reactor is shut down when the neutron absorption control device 29 is inserted into the core 12 are passively cooled as described above. Heat is removed by system 32.

  That is, the heat generated in the core 12 during normal operation and the residual decay heat generated in the core 12 when the reactor is stopped are first transmitted to the reactor vessel 11 via the liquid metal coolant 13. Next, the heat of the reactor vessel 11 is transferred to the guard vessel 19 by heat radiation, heat conduction by a gas (for example, inert gas) filled in the gap 26 between the reactor vessel 11 and the guard vessel 19 or natural convection. Communicated. Next, the heat of the guard vessel 19 is transmitted to the heat collector 34 by heat radiation, and is also transmitted to the air in the upflow passage 36 by natural convection of the air in the upflow passage 36. Furthermore, a part of the heat of the heat collector 34 is transmitted to the concrete structure 31A by thermal radiation. The heat of the concrete structure 31 </ b> A and the heat collector 34 is transmitted to the air in the downflow passage 35.

  The passive cooling system 32 of this embodiment further includes a heat absorbing member 41 and a heat sink 42 (FIG. 2), and has a function of passively cooling the liquid metal coolant 13 in the reactor vessel 11 when the reactor is stopped.

  As shown in FIGS. 1 and 2, the heat absorbing member 41 is formed in a ring shape with a material having high thermal conductivity. The endothermic member 41 is disposed in an upper part of the reactor vessel 11, that is, above the intermediate heat exchanger 21 in a state where at least a part is immersed in the liquid metal coolant 13. The endothermic member 41 is supported by the upper plug 24 via a hanging rod 43 serving as an endothermic member supporting means extending above the reactor vessel and an attaching / detaching ring 44. That is, as shown in FIG. 2, the heat absorbing member 41 is fixed to the lower end of the hanging rod 43, and the detachable ring 44 is fixed to the upper end of the hanging 41. The detachable ring 44 is housed in a storage box 45 installed on the upper plug 24 and attached to the storage box 45. As a result, the heat absorbing member 41 is supported by the upper plug 24 via the hanging rod 43, the attachment / detachment ring 44 and the storage box 45. Among these, the hanging rod 43 and the attaching / detaching ring 44 have a shape and heat conductivity that can transfer heat of the liquid metal coolant 13 satisfactorily.

  The heat sink 42 has a function of radiating heat into the air, and is stored in the storage box 45 as shown in FIG. 2 and is disposed above the reactor vessel 11 and the suspension rod 43. The heat sink 42 has a ring shape like the heat absorbing member 41, and a plurality of gripped rods 46 are erected on the upper surface, and a plurality of heat transfer rods 47 are suspended on the lower surface. These gripped rods 46 are gripped (held) by an electromagnetic locking ring 48 serving as a heat sink holding means, and the electromagnetic locking ring 48 is supported by an upper mounting structure 49 provided on the top surface of the storage box 45. . Thereby, the heat sink 42 is supported by the storage box 45 via the gripped rod 46, the electromagnetic locking ring 48, and the upper mounting structure 49.

  The plurality of heat transfer rods 47 suspended from the lower surface of the heat sink 42 are configured to be inserted into a plurality of fitting holes 50 formed in the attachment / detachment ring 44 so as to be fitted. Further, as shown in FIG. 3A, the electromagnetic catching ring 48 is closed in the energized state to grip the gripped rod 46 and is integrated with the gripped rod 46. At this time, since the heat sink 42 is separated from the heat absorbing member 41, it is thermally insulated from the heat absorbing member 41. Further, as shown in FIG. 3B, the electromagnetic locking ring 48 is opened when the power is lost (lost), and the gripping of the gripped rod 46 is released. At this time, the heat sink 42 falls, and the heat transfer rod 47 of the heat sink 42 is fitted into the fitting hole 50 of the attachment / detachment ring 44. As a result, the heat sink 42 is thermally connected to the heat absorbing member 41 via the heat transfer rod 47, the attachment / detachment ring 44 and the suspension rod 43.

  Accordingly, during energization operation of the liquid metal cooling reactor 10, the electromagnetic locking ring 48 holds the gripped rod 46 of the heat sink 42, and the heat sink 42 accommodates the upper plug 24 via the gripped rod 46 and the electromagnetic locking ring 48. Since it is supported by the upper mounting structure 49 of the box 45, the heat sink 42 is thermally cut off from the heat absorbing member 41 and does not perform a heat dissipation function. Further, when the power is lost when the liquid metal cooling reactor 10 is stopped, the electromagnetic trap ring 48 is opened, so that the heat sink 42 is dropped, and the heat transfer rod 47 of the heat sink 42 is fitted into the fitting hole 50 of the attachment / detachment ring 44. To fit. Thus, the heat sink 42 is thermally connected to the heat absorbing member 41 via the heat transfer rod 47, the attachment / detachment ring 44, and the suspension rod 43, and the heat of the liquid metal coolant 13 in the reactor vessel 11 is transferred to the reactor vessel. 11 dissipates heat into the gas outside.

With the configuration as described above, according to the present embodiment, the following effect (1) is obtained.
(1) The endothermic member 41 immersed in the liquid metal coolant 13 in the reactor vessel 11 is thermally connected to the heat sink 42 disposed above the reactor vessel 11 when the reactor is stopped and when the power is lost. Let As a result, the heat of the liquid metal coolant 13 in the reactor vessel 11 is transferred from the heat absorbing member 41 to the heat sink 42 through the suspension rod 43, the detachable ring 44 and the heat transfer rod 47 by heat conduction. The metal coolant 13 can be efficiently cooled. As a result, the heat removal performance of the core 12 can be improved.
In the present embodiment, the ring-shaped heat sink 42 and the detachable ring 44 are connected. However, these are only formed in a ring shape in consideration of the neutron absorption control device drive mechanism 30 and the like. If there is no interference with the device, for example, both may be simple disks. Further, the heat sink 42 and the attachment / detachment ring 44 only need to be thermally connectable. For example, the connection mechanism such as the heat transfer rod 47 is omitted, and the heat sink 42 is simply placed on the attachment / detachment ring 44. May be.
Further, although the heat absorbing member 41 has been described as a ring shape, it may be polygonal or may not be continuously connected. In order not to inhibit the flow of the liquid metal coolant and to increase the surface area, for example, a perforated plate, a lattice shape, or a configuration in which a plurality of plates are arranged at predetermined intervals is more preferable.
Further, one or both of the heat sink 42 and the attachment / detachment ring 44 may not be formed as an integral ring. For example, the heat-absorbing member 41 simply has a structure in which a plurality of hanging rods 43 are erected (there is no detachable ring 44), and a heat sink in which a connecting portion with the hanging rod 43 and a heat radiating portion are integrated is provided for each hanging rod 43. The structure arrange | positioned above may be sufficient.
As described above, the heat absorbing member 41, the heat sink 42, and the structure that thermally connects them can be variously modified. From the viewpoint of cooling efficiency, it is desirable that the contact area between the heat absorbing member 41 and the heat sink 42 and the structures interposed therebetween, and the surface area of the heat sink are large.
Further, although the heat sink 42 has been described as being maintained in a state where the heat absorbing member 41 is separated by the electromagnetic catching ring 48 as the heat sink holding means and the gripped rod 46, it is not limited to this configuration. It is only necessary to support the heat sink 42 in such a configuration that the engagement is automatically released when the power source is lost. For example, a recess on the side of the heat sink 42 is provided, and power is supplied by being inserted into the recess. The storage box 45 may be provided with a latch that supports the heat sink 42 while the heat sink 42 is in operation.

[B] Second Embodiment (FIGS. 1 and 4)
FIG. 4 is a perspective view showing a heat absorbing member, a heat sink, and a cooling device in a second embodiment of the passive cooling system for a liquid metal cooled nuclear reactor according to the present invention. In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

  The difference between the passive cooling system 55 of the present embodiment and the first embodiment is that the cooling passage 33 is on the side of the upflow passage 36, that is, near the air discharge port 40 of the air discharge pipe 39 communicating with the upflow passage 36. In addition, a cooling device 57 (indicated by a two-dot chain line in FIG. 1) having a heat radiator 56 as a heat radiating portion is built in, and the heat radiator 56 of the cooling device 57 is interposed via a heat transfer bar 58 or the like as a heat transfer member. The heat sink 42 is configured to be connectable.

  That is, in the device housing 59 of the cooling device 57, the heat radiator 56 provided with a plurality of heat transfer rods 60, a pedestal 61 attached to the end of the heat transfer bar 58, and when energized An electromagnetic catching ring 62 that accommodates the heat radiating body 56 on the apparatus housing 59 while holding the heat transfer rod 60 is accommodated.

  When the power is lost, the electromagnetic catching ring 62 opens to release the heat transfer rod 60, whereby the radiator 56 and the heat transfer rod 60 are dropped, and the heat transfer rod 60 is inserted into the fitting hole 63 of the cradle 61. And fit. As a result, the radiator 56 is thermally connected to the heat sink 42 via the heat transfer rod 60, the pedestal 61 and the heat transfer bar 58, and when the power supply disappears when the liquid metal cooled reactor 10 is stopped, the reactor vessel 11 The heat of the liquid metal coolant 13 is radiated by the heat sink 42 and also radiated from the radiator 56 of the cooling device 57. Further, during the normal operation of the liquid metal cooled nuclear reactor 10, since the electromagnetic trap ring 62 holds the heat transfer rod 60 as described above, the heat transfer rod 60 does not fit into the fitting hole 63 of the cradle 61. The radiator 56 is thermally insulated from the heat sink 42.

  Therefore, according to this embodiment, in addition to the same effect as the effect (1) of the first embodiment, the following effects (2) and (3) are achieved.

  (2) Since the radiator 56 of the cooling device 57 is thermally connected to the heat sink 42 via the heat transfer bar 58 and the like when the power source is lost when the liquid metal cooled reactor 10 is stopped, the inside of the reactor vessel 11 The heat of the liquid metal coolant 13 can be dissipated by the heat sink 42 and can also be dissipated by the heat dissipating body 56 of the cooling device 57 via the heat transfer bar 58 and the like, so that the liquid metal coolant 13 can be cooled more efficiently. At the same time, the air temperature in the vicinity of the air discharge port 40 in the air discharge pipe 39 of the cooling passage 33 rises due to heat radiation by the heat radiating body 56, so the flow rate of the air rising in the air discharge pipe 39 and the upflow passage 36 is increased. Can be made. As a result, the flow velocity of the air flowing through the entire cooling passage 33 is increased and the flow rate can be increased, so that the liquid metal coolant 13, the reactor vessel 11, the guard vessel 19, and the concrete structure 31A are more efficiently used by this air. Can be cooled. For these reasons, the residual decay heat generated in the core 12 can be more suitably removed.

  (3) During normal operation of the liquid metal cooled reactor 10, the radiator 56 of the cooling device 57 is thermally disconnected from the heat sink 42, and the heat sink 42 is thermally disconnected from the heat absorbing member 41 in the reactor vessel 11. Therefore, the amount of heat of the liquid metal coolant 13 during the normal operation can be reduced through the heat absorbing member 41 and the like.

In the second embodiment, the heat transfer rod 60, the cradle 61 and the electromagnetic catching ring 62 in the cooling device 57 are omitted, and the heat radiator 56 is always thermally connected to the heat transfer bar 58. Good. In this case, although the effect (3) cannot be realized, the structure of the cooling device 57 can be simplified, and the robustness of the device is improved.
Further, similarly to the description of the heat absorbing member 41 and the like in the first embodiment, the heat radiator 56 and the cradle 61 can be variously modified.

[C] Third embodiment (FIG. 5)
FIG. 5 is a side sectional view showing a liquid metal cooled nuclear reactor to which a third embodiment of the passive cooling system for a liquid metal cooled nuclear reactor according to the present invention is applied. In the third embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

  The passive cooling system 65 of this embodiment is different from that of the first embodiment in that the upstream connection pipe 66 as the first connection pipe is located on the guard vessel 19 at a position different from the upstream connection pipe 66, for example, the guard. A downstream connection pipe 67 as a second connection pipe is provided below the vessel 19, and the upstream connection pipe 66 and the downstream connection pipe 67 are at least partially in the downflow passage 35 of the cooling passage 33. Is connected to a heat radiation pipe 68 arranged extending in the vertical direction.

  The upstream connection pipe 66 and the downstream connection pipe 67 pass through the guard vessel 19 and the heat collector 34 and extend into the downflow passage 35, and their ends are connected to the heat radiation pipe 68. Further, a melting valve 69 is installed in the upstream connection pipe 66 and the downstream connection pipe 67. This melting valve 69 is configured so that gas (for example, inert gas) in the gap 26 between the reactor vessel 11 and the guard vessel 19 can flow into the heat radiation pipe 68. The melting valve 69 may be provided in the heat radiation pipe 68.

  That is, when the temperature of the liquid metal coolant 13 exceeds the design temperature when the liquid metal cooling reactor 10 is stopped, the melting valve 69 is opened. When the melting valve 69 is opened, the high-temperature gas in the gap 26 between the reactor vessel 11 and the guard vessel 19 flows down in the heat radiation pipe 68 through the upstream connection pipe 66 and flows in the downflow passage 35. After being cooled by exchanging heat with the flowing low-temperature air, it is returned to the gap 26 through the downstream connection pipe 67 and circulated. In this way, the gas in the gap 26 between the reactor vessel 11 and the guard vessel 19 is directly cooled.

  Since it was configured as described above, this embodiment also exhibits the same effect (4) as the effects (1) to (3) of the first and second embodiments.

  (4) When the temperature of the liquid metal coolant 13 exceeds the design temperature when the liquid metal cooled reactor 10 is stopped, the gas in the gap 26 between the reactor vessel 11 and the guard vessel 19 flows in the heat radiation pipe 68. Cooled by the air flowing through the downflow passage 35. For this reason, the reactor vessel 11 can be efficiently cooled.

[D] Fourth embodiment (FIG. 6)
FIG. 6 is a side sectional view showing a liquid metal cooled nuclear reactor to which a fourth embodiment of the passive cooling system for a liquid metal cooled nuclear reactor according to the present invention is applied. In the sixth embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

  The passive cooling system 70 of this embodiment is different from the first embodiment in that an outflow pipe 71 is provided above the guard vessel 19 so as to open to the downflow path 35 of the cooling passage 33, and this outflow pipe 71. The inflow pipe 72 is connected to an inflow pipe 73 extending vertically upward in the downflow passage 35 at a lower position, for example, the lower part of the guard vessel 19. The inflow pipe 73 is provided to open to the downflow passage 35.

  The outflow pipe 71 and the inflow pipe 72 extend through the guard vessel 19 and the heat collector 34 to the downflow passage 35 and include a melting valve 74. The melting valve 74 allows the gas in the gap 26 between the reactor vessel 11 and the guard vessel 19 to flow out into the downflow passage 35 via the outflow pipe 71, and in the downflow passage 35 corresponding to the outflow. This air is configured to be able to flow into the gap 26 through the inflow pipe 73 and the inflow pipe 72.

  That is, when the temperature of the liquid metal coolant 13 exceeds the design temperature when the liquid metal cooling reactor 10 is stopped, the melting valve 74 is opened. By opening the melting valve 74, the high-temperature gas in the gap 26 between the reactor vessel 11 and the guard vessel 19 flows out into the downflow passage 35 through the outflow pipe 71. The same amount of low-temperature air as the outflowing gas is taken into the inflow pipe 73 from the downflow passage 35 and flows into the gap 26 through the inflow pipe 72, and the temperature rise in the gap 26 is suppressed.

  Since it was configured as described above, this embodiment also exhibits the same effect (5) as the effects (1) to (3) of the first and second embodiments.

  (5) When the temperature of the liquid metal coolant 13 exceeds the design temperature when the liquid metal cooling reactor 10 is stopped, the high-temperature gas in the gap 26 between the reactor vessel 11 and the guard vessel 19 passes through the cooling passage 33. The gas flows out into the downflow passage 35 and the same amount of low-temperature air as the outflowed gas is taken in from the downflow passage 35 through the inflow pipe 73 and flows into the gap 26. For this reason, since the temperature rise in the gap 26 is suppressed by the inflow of the low-temperature air, the reactor vessel 11 can be efficiently cooled.

[E] Fifth embodiment (FIG. 7)
FIG. 7 is a side sectional view showing a liquid metal cooled nuclear reactor to which a fifth embodiment of the passive cooling system for a liquid metal cooled nuclear reactor according to the present invention is applied. In the fifth embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is simplified or omitted.

  The passive cooling system 75 of the present embodiment is different from the first embodiment in that the reactor vessel 11 is penetrated through the reactor vessel 11 and into the gap 26 between the reactor vessel 11 and the guard vessel 19. An opening lead-out pipe 76 is provided, and the liquid metal coolant 13 in the reactor vessel 11 can be introduced into the gap 26 through the lead-out pipe 76.

  The outlet pipe 76 is provided at a location where the liquid metal coolant 13 is filled in the upper part of the reactor vessel 11 (that is, a position lower than the liquid level of the liquid metal coolant 13), and includes a melting valve 77. This melting valve 77 is opened when the liquid metal cooling reactor 10 is stopped and the liquid metal coolant 13 exceeds the design temperature. When the melting valve 77 is opened, the liquid metal coolant 13 in the reactor vessel 11 is introduced into the gap 26 between the reactor vessel 11 and the guard vessel 19 through the outlet pipe 76, and the heat conduction in the gap 26 is performed. The rate is increased.

  Since it was configured as described above, this embodiment also exhibits the following effect (6) in addition to the same effects as the effects (1) to (3) of the first and second embodiments.

  (6) When the temperature of the core 12 is equal to or higher than the design temperature when the liquid metal cooled reactor 10 is stopped, the liquid metal coolant 13 in the reactor vessel 11 passes through the outlet pipe 76 and the reactor vessel 11 and the guard vessel. 19 is introduced into the gap 26, and the thermal conductivity of the gap 26 is increased. For this reason, the temperature difference between the reactor vessel 11 and the guard vessel 19 is reduced, and the reactor vessel 11 can be efficiently cooled by the air flowing through the upward flow passage 36 of the cooling passage 33.

[F] Sixth embodiment (FIG. 8)
FIG. 8 is a side sectional view showing a liquid metal cooled nuclear reactor to which a sixth embodiment of the passive cooling system for a liquid metal cooled nuclear reactor according to the present invention is applied. In the sixth embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description is simplified or omitted.

  The passive cooling system 80 of this embodiment is different from the first embodiment in that an injection pipe 81 is provided on the upper part of the guard vessel 19, and this injection pipe 81 is installed on the outside of the guard vessel 19. The liquid metal (for example, liquid sodium) stored in the liquid metal storage container 82 is connected to the container 82 and can be injected into the gap 26 between the reactor container 11 and the guard vessel 19 through the injection pipe 81. It is a point.

  The injection pipe 81 is provided through the guard vessel 19 and includes a melting valve 83. This melting valve 83 is opened when the liquid metal cooling reactor 10 is stopped and the liquid metal coolant 13 exceeds the design temperature. When the melting valve 83 is opened, the liquid metal in the liquid metal storage container 82 is injected into the gap 26 between the reactor vessel 11 and the guard vessel 19 through the injection pipe 81, and the thermal conductivity of the gap 26 is increased. Enhanced.

  Since it was configured as described above, this embodiment also has the following effects (7) in addition to the same effects as the effects (1) to (3) of the first and second embodiments.

  (7) When the temperature of the core 12 is equal to or higher than the design temperature when the liquid metal cooled reactor 10 is stopped, the liquid metal in the liquid metal storage vessel 82 passes through the injection pipe 81, and the reactor vessel 11 and the guard vessel 19 The heat conductivity of the gap 26 is increased. For this reason, the temperature difference between the reactor vessel 11 and the guard vessel 19 is reduced, and the reactor vessel 11 can be efficiently cooled by the air flowing through the upward flow passage 36 of the cooling passage 33.

[G] Seventh embodiment (FIG. 9)
FIG. 9 is a side sectional view showing a liquid metal cooled nuclear reactor to which a seventh embodiment of the passive cooling system for a liquid metal cooled nuclear reactor according to the present invention is applied. In the seventh embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is simplified or omitted.

  The passive cooling system 85 of the present embodiment is different from the first embodiment in that the cooling passage 33 is on the side of the upflow passage 36, that is, in the vicinity of the air discharge port 40 of the air discharge pipe 39 connected to the upflow passage 36. A heat exchanger 86 is built in, and a pipe 87 having an immersion part 88 immersed in the liquid metal coolant 13 in the reactor vessel 11 is connected to the heat exchanger 86 to form a loop-shaped flow path. It is a point configured to do.

  The piping 87 is provided through the reactor vessel 11 and the guard vessel 19, and a part thereof is connected to the heat exchanger 86 and is filled with a refrigerant (for example, liquid sodium). Further, a melting valve 89 is disposed in the immersion part 88 of the pipe 87. The melting valve 89 is configured so that the refrigerant cannot flow through the pipe 87.

  When the temperature of the liquid metal coolant 13 exceeds the design temperature when the liquid metal cooling reactor 10 is stopped, the melting valve 89 is opened, and the refrigerant can freely flow through the pipe 87. And the high temperature refrigerant | coolant heated with the liquid metal coolant 13 in the reactor vessel 11 in the immersion part 88 of the piping 87 becomes that density becomes small, and flows into the heat exchanger 86 side. In the heat exchanger 86, the refrigerant is cooled by the air flowing through the air discharge pipe 39 of the cooling passage 33, becomes a low temperature, increases in density, and flows in the pipe 87 toward the immersion portion 88. In this way, the refrigerant in the pipe 87 circulates between the immersion part 88 and the heat exchanger 86, and the liquid metal coolant 13 in the reactor vessel 11 is cooled.

  Since it was configured as described above, this embodiment also exhibits the same effect (8) as the effects (1) to (3) of the first and second embodiments.

  (8) When the temperature of the core 12 is equal to or higher than the design temperature when the liquid metal cooled reactor 10 is stopped, the refrigerant in the pipe 87 is transferred to the liquid metal coolant in the reactor vessel 11 at the immersion portion 88 of the pipe 87. 13 and is cooled by the air flowing through the air discharge pipe 39 of the cooling passage 36 by the heat exchanger 86. For this reason, the liquid metal coolant 13 in the reactor vessel 11 can be efficiently cooled via this refrigerant.

[H] Eighth Embodiment (FIG. 10)
FIG. 10 is a side sectional view showing a liquid metal cooled nuclear reactor to which an eighth embodiment of the passive cooling system for a liquid metal cooled nuclear reactor according to the present invention is applied. In the eighth embodiment, portions similar to those in the first embodiment are denoted by the same reference numerals, and description thereof is simplified or omitted.

  The passive cooling system 90 of the present embodiment is different from the first embodiment in that the cooling passage 33 is on the side of the upflow passage 36, that is, in the vicinity of the air discharge port 40 of the air discharge pipe 39 connected to the upflow passage 36. The heat exchanger 91 is built in, a part of the pipe 92 is disposed in the gap 26 between the reactor vessel 11 and the guard vessel 19, the pipe 92 penetrates the guard vessel 19, and the other part of the pipe 92. The point is that the pipe 92 is connected to the heat exchanger 91 so as to form a loop-shaped flow path.

  The pipe 92 is filled with a refrigerant (for example, liquid sodium), and heat from the reactor vessel 11 is transmitted to the refrigerant mainly by thermal radiation and heat conduction. Further, the pipe 92 is provided with a melting valve 93 at a portion located in the gap 26, for example. The melting valve 93 is configured to prevent the refrigerant from flowing through the pipe 92.

  That is, when the temperature of the gap 26 exceeds the design temperature when the liquid metal cooling reactor 10 is stopped, the melting valve 93 is opened, and the refrigerant can freely flow through the pipe 92. And the high temperature refrigerant | coolant heated by the reactor vessel 11 in the part located in the clearance gap 26 in the piping 92 becomes that density becomes small, and flows into the heat exchanger 91 side. In the heat exchanger 91, the refrigerant is cooled by the air flowing through the air discharge pipe 39 of the cooling passage 33, becomes low temperature, increases in density, and flows in the pipe 92 toward the portion located in the gap 26. . In this way, the refrigerant in the pipe 92 circulates through the heat exchanger 91 and cools the gas in the gap 26.

  Since it was configured as described above, this embodiment also exhibits the same effect (9) as the effects (1) to (3) of the first and second embodiments.

  (9) When the temperature of the core 12 is equal to or higher than the design temperature when the liquid metal cooled reactor 10 is stopped, the refrigerant in the pipe 92 is heated by the reactor vessel 11 in the portion located in the gap 26, and the heat exchanger The air is cooled by the air flowing through the air discharge pipe 39 of the cooling passage 33 at 91. For this reason, the gas in the gap 26 is efficiently cooled through this refrigerant, and as a result, the reactor vessel 11 can be efficiently cooled.

  As described above, the present invention has been described based on each embodiment, but the present invention is not limited to this, and the constituent elements may be variously modified without departing from the scope of the present invention. You may combine a component suitably.

  For example, in the third to eighth embodiments, the heat absorbing member 41 and the heat sink 42 of the first embodiment or the heat absorbing member 41 of the second embodiment, the heat sink 42 and the cooling device 57 are described. The first and second embodiments may not be applied. Also in this case, the third to eighth embodiments can sufficiently exhibit the passive cooling function against the residual decay heat generated in the core 12.

DESCRIPTION OF SYMBOLS 10 Liquid metal cooling reactor 11 Reactor vessel 12 Core 13 Liquid metal coolant 19 Guard vessel 24 Upper plug 26 Gap 32 Passive cooling system 33 Cooling passage 34 Heat collector 35 Downflow passage 36 Upflow passage 37 Air introduction pipe (intake air) aisle)
39 Air exhaust pipe (exhaust passage)
41 endothermic member 42 heat sink 43 hanging rod (endothermic member support means)
48 Electromagnetic locking ring (heat sink holding means)
55 Passive cooling system 56 Radiator (Heat dissipation part)
57 Cooling device 58 Bar for heat transfer (heat transfer member)
65 Passive cooling system 66 Upstream connection piping (first connection piping)
67 Downstream connection piping (second connection piping)
68 Radiation pipe 70 Passive cooling system 71 Outflow pipe 72 Inflow pipe 73 Inflow pipe 75 Passive cooling system 76 Outlet pipe 80 Passive cooling system 81 Inlet pipe 82 Liquid metal storage container 85 Passive cooling system 86 Heat exchanger 87 Pipe 88 Immersion section 90 Passive cooling system 91 Heat exchanger 92 Piping

Claims (10)

An endothermic member disposed at the top of the reactor vessel in which the liquid metal coolant is housed, at least partially immersed in the liquid metal coolant;
An endothermic member supporting means for supporting the endothermic member and extending above the reactor vessel;
A heat sink disposed above the heat absorbing member support means;
The heat sink holding means for holding the heat sink,
A passive cooling system for a liquid metal cooled nuclear reactor, wherein the heat sink is dropped when the holding by the heat sink holding means is released and is thermally connected to the heat absorbing member via the heat absorbing member supporting means. . 2. The passive cooling system for a liquid metal cooled nuclear reactor according to claim 1, wherein the heat sink holding means is configured to release the holding of the heat sink when the power source is lost. A guard vessel for storing the reactor vessel;
A heat collector provided between the guard vessel and the silo that houses the guard vessel;
An intake passage for taking air into the silo;
An exhaust passage for discharging the air inside the silo,
Between the heat collector and the silo, a downflow passage is formed in which air taken in from the intake flow path descends,
Between the heat collector and the guard vessel, an upflow passage is formed in which air that has passed through the downflow passage rises,
3. The passive cooling system for a liquid metal cooled reactor according to claim 1, wherein the air that has passed through the upflow passage is discharged from the exhaust passage. 4. A heat dissipating part disposed in the exhaust flow path;
The passive cooling system for a liquid metal cooled nuclear reactor according to claim 3, further comprising: a heat transfer member that connects the heat sink and the heat radiating unit. A first connection pipe provided through the guard vessel;
A second connection pipe penetrating the guard vessel and provided at a position different from the first connection pipe;
A heat dissipating pipe connected to the first and second connecting pipes, at least a part of which is located in the downflow passage;
A passive cooling system for a liquid metal cooled nuclear reactor according to claim 3 or 4, further comprising a melting valve provided on the connection pipe or the heat radiation pipe. An outflow pipe passing through the guard vessel and opening into the downflow passage;
An inflow pipe that passes through the guard vessel and opens into the downflow passage at a position lower than the outflow pipe; and
The passive cooling system for a liquid metal cooled nuclear reactor according to any one of claims 3 to 5, further comprising a melting valve provided in each of the outflow pipe and the inflow pipe. A lead-out pipe that penetrates the reactor vessel at a position lower than the liquid level of the liquid metal coolant and opens into a gap between the reactor vessel and a guard vessel;
A passive cooling system for a liquid metal cooled nuclear reactor according to any one of claims 3 to 6, further comprising a melting valve provided in the outlet pipe. An injection pipe passing through the guard vessel;
A liquid metal storage container connected to the injection pipe and storing liquid metal therein;
The passive cooling system for a liquid metal cooled nuclear reactor according to any one of claims 3 to 7, further comprising a melting valve provided in the injection pipe. A part is located in the exhaust passage, a part is immersed in the liquid metal coolant in the reactor vessel, and a loop-like passage is formed through the reactor vessel and the guard vessel. The passive cooling system for a liquid metal cooled nuclear reactor according to any one of claims 3 to 8, further comprising a pipe through which a refrigerant flows. A part is located in the exhaust flow path, a part is located in the gap between the reactor vessel and the guard vessel, and a loop-like flow path is formed through the guard vessel. A passive cooling system for a liquid metal cooled nuclear reactor according to any one of claims 3 to 9, further comprising:

Images