JP2013145161A - Spent fuel storage facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suitably remove decay heat of spent fuel stored in a spent fuel storage pool even when all the power supplies are lost.SOLUTION: A spent fuel storage facility 10 has: a spent fuel storage pool 11 for removing decay heat of spent fuel by allowing spent fuel A to sink in pool water 15; and a pool water cooling purification system 12 provided with a pump 17 and a heat exchanger 19 for leading the pool water to a heat exchanger for cooling by the drive of the pump and returning the pool water to the spent fuel storage pool. The spent fuel storage facility 10 also has: a heat pipe 13 having an evaporating section 21 that is immersed in the pool water 15 in the spent fuel storage pool 11, and a condensing section 22 that is positioned above the water surface of the pool water; and a tube-like object 14 having the condensing section of the heat pipe therein and a passage 23 that is defined between the condensing section and the tube-like object for allowing air to flow.

Description

  The present invention relates to a spent fuel storage facility for storing spent fuel used in a nuclear reactor.

  The spent fuel used in the nuclear reactor is usually temporarily stored in a spent fuel storage pool filled with cooling water (hereinafter referred to as pool water). For example, in a nuclear power plant, as shown in FIG. 6, the spent fuel 3 is submerged in the pool water 4 inside the spent fuel storage pool 2 installed in the reactor building 1. The decay heat generated from the spent fuel 3 is transmitted to the pool water 4 in the spent fuel storage pool 2, and the pool water 4 flows into the skimmer surge tank 5 through the pump 7 of the pool water cooling and purification system 6. Then, the impurities are removed by the filtration desalting apparatus 8, the decay heat of the spent fuel 3 is removed by the heat exchanger 9, and then returned to the spent fuel storage pool 2 again. The heat exchanged by the heat exchanger 9 is released from the secondary system of the heat exchanger 9 to the sea through a reactor equipment cooling system (not shown).

  In this way, water is injected into the spent fuel storage pool 2 by circulating the pool water 4 using a dynamic device such as a pump 7. When all power is lost due to some event, an emergency diesel generator (not shown) is activated and the dynamic equipment is activated. The pool water 4 evaporates due to decay heat, the water level in the spent fuel storage pool 2 decreases, the pool water 4 is lost, and the spent fuel 3 may be damaged.

  For such an event, for example, in the reactor building 1 of the nuclear power plant, steam is also generated by the reactor. A technique of operating a dynamic device by operating an injector (not shown) to secure a power source is disclosed (see Patent Document 1). Alternatively, there is a technique in which water is poured into the spent fuel storage pool 2 by directly using a steam injector. Further, there is a technique in which a tank (not shown) is provided on the roof of the reactor building 1 and a system for injecting water from the tank to the spent fuel storage pool 2 of the reactor building 1 in an emergency is provided.

JP-A-3-229196

  As described above, the cooling of the spent fuel is continued even in the case of an emergency in which a system (for example, the pool water cooling and purification system 6) that circulates the cooling water to the spent fuel storage pool 2 fails due to some event. Thus, it is necessary to provide an alternative cooling facility. The technique disclosed in Patent Document 1 can be effective in conditions and places where steam is generated, but the system becomes complicated and operation becomes difficult in conditions and places where steam is not generated. .

  The object of the present invention has been made in view of the above circumstances, and spent fuel storage that can suitably remove the decay heat of spent fuel stored in the spent fuel storage pool even when the entire power source is lost. To provide facilities.

  An embodiment of the present invention includes a spent fuel storage pool that submerges spent fuel in pool water to remove decay heat of the spent fuel, a pump and a heat exchanger, and the pool water is driven by the pump. In a spent water storage system having a pool water cooling system that guides the heat to the heat exchanger and cools it back to the spent fuel storage pool, wherein an evaporation section is immersed in the pool water of the spent fuel storage pool A heat pipe in which a condensing part is positioned above the water surface of the pool water, and a cylindrical body that encloses the condensing part of the heat pipe and in which a flow path for flowing air is formed between the heat pipe and the condensing part. , Characterized by having.

  According to the embodiment of the present invention, when the pool water is cooled using the heat pipe using the temperature difference between the pool water and the air of the spent fuel storage pool, the condensation portion and the cylindrical body of the heat pipe By generating an upward flow due to the difference in air density in the flow path between them, the amount of heat released from the condensing part of the heat pipe can be increased.

The block diagram which shows 1st Embodiment of the spent fuel storage equipment which concerns on this invention. The cylindrical body of FIG. 1 is shown, (A) is a partial longitudinal cross-sectional view, (B) is a cross-sectional view. (A) is a block diagram which shows 2nd Embodiment of the spent fuel storage equipment which concerns on this invention, (B) is a perspective view which shows the cover used for the spent fuel storage equipment of FIG. 3 (A). The block diagram which shows 3rd Embodiment of the spent fuel storage equipment which concerns on this invention. The deformation | transformation form of the duct of FIG. 4 is shown, (A) is a block diagram, (B) is sectional drawing which follows the VV line of FIG. 5 (A). The block diagram which shows the conventional spent fuel storage facility.

Embodiments for carrying out the present invention will be described below with reference to the drawings.
[A] First embodiment (FIGS. 1 and 2)
FIG. 1 is a configuration diagram showing a first embodiment of a spent fuel storage facility according to the present invention. A spent fuel storage facility 10 shown in FIG. 1 includes a spent fuel storage pool 11, a pool water cooling and purification system 12 as a pool water cooling system, a heat pipe 13, and a cylindrical body 14.

  The spent fuel storage pool 11 removes the decay heat of the spent fuel A by immersing the spent fuel A used in a nuclear reactor (not shown) of the nuclear power plant in pool water (cooling water) 15. is there. That is, the spent fuel storage pool 11 is provided in a reactor building (not shown) and is filled with the pool water 15. The spent fuel A is temporarily stored in the pool water 15 while being submerged. During this time, the collapsing action of the pool water 15 and the pool water cooling and purification system 12 removes the decay heat of the spent fuel A.

  The pool water cooling and purification system 12 is configured by sequentially arranging a pump 17, a filtration desalinator 18, and a heat exchanger 19 in a system pipe 16. The system pipe 16 has an end on the pump 17 side connected to the skimmer surge tank 20 and an end on the heat exchanger 19 side connected to the spent fuel storage pool 11.

  After the pool water 15 in the spent fuel storage pool 11 flows into the skimmer surge tank 20, the pump 17 is driven to guide the filtration demineralizer 18 to remove impurities, and then to the heat exchanger 19. It is then cooled and then returned to the spent fuel storage pool 11. The secondary system of the heat exchanger 19 dissipates heat to seawater through a reactor equipment cooling system (not shown), so that the decay heat of the spent fuel A is removed by the heat exchanger 19 via the pool water 15. The

  The heat pipe 13 includes an evaporation unit 21 and a condensing unit 22. The evaporating unit 21 is immersed in the pool water 15 of the spent fuel storage pool 11, and the condensing unit 22 is positioned above the water surface of the pool water 15. The heat pipe 13 is generally configured by sealing a small amount of hydraulic fluid in a sealed container in a vacuum state and providing a capillary structure on the inner wall of the sealed container. When the evaporation section 21 of the heat pipe 13 is heated, the working fluid evaporates in the evaporation section 21, moves to the low-temperature condensation section 22, and condenses to dissipate heat. The condensed working fluid returns to the evaporation unit 21 by capillary action. Heat is transferred by continuously generating such a phase change.

  When the pool water cooling and purification system 12 breaks down for some reason, the temperature of the pool water 15 in the spent fuel storage pool 11 rises due to decay heat of the spent fuel A. Then, the working fluid evaporates inside the evaporation unit 21 of the heat pipe 13, and the generated vapor moves to the condensation unit 22 and is condensed due to a temperature difference from the air (atmosphere) to become a liquid. Reflux. Thus, by using the heat pipe 13, heat (that is, use of the pool water 15 in the spent fuel storage pool 11 is caused by natural circulation caused by a temperature difference between the pool water 15 in the spent fuel storage pool 11 and air. The decay heat of the spent fuel A) is radiated to the air.

  However, since the temperature difference between the pool water 15 in the spent fuel storage pool 11 and the air (atmosphere) is as small as about 30 ° C., the pool water 15 is cooled to remove the decay heat of the spent fuel A, and the pool water In order to keep the temperature of 15 constant, the contact area between the condensing part 22 of the heat pipe 13 and the air (atmosphere) becomes enormous. Therefore, in the present embodiment, the cylindrical body 14 that includes the condensing part 22 of the heat pipe 13 is provided.

  The cylindrical body 14 is formed in a cylindrical shape, and the lower end of the cylindrical body 14 encloses the periphery of the condensation portion 22 of the heat pipe 13 to enclose the condensation portion 22, and a flow path for flowing air between the condensation portion 22. 23 is formed. The air in the flow path 23 is heated by the heat from the condensing part 22 of the heat pipe 13, thereby causing a difference in air density between the upper area and the lower area of the flow path 23, and the air in the flow path 23. A rise occurs and the amount of heat released from the condensing part 22 of the heat pipe 13 increases.

  Here, the length L in the vertical direction of the cylindrical body 14 is at least about twice as long as the length N in the vertical direction of the condensing part 22 in the heat pipe 13 (preferably about the size of the cylindrical body 14 is avoided in order to avoid an increase in size). 2). As a result, the temperature difference between the air in the upper region and the lower region in the flow path 23 inside the cylindrical body 14 increases, and the air density difference based on this temperature difference also increases, so that the air flowing in the flow path 23 The flow rate of the upward flow can be increased, and the amount of heat released from the condensing part 22 of the heat pipe 13 is increased.

  Further, as shown in FIG. 2, a large number of fine protrusions 24 are formed substantially uniformly on the inner surface of the cylindrical body 14. This is because the development of the boundary layer of air is suppressed on the inner surface of the cylindrical body 14 and the friction loss due to the inner surface of the cylindrical body 14 is reduced. That is, the flow rate of the air rising flow that flows through the flow path 23 in the cylindrical body 14 is the difference in density due to the temperature difference of the air between the upper region and the lower region of the flow path 23 and the friction loss on the inner surface of the cylindrical body 14. Determined by. For this reason, by providing the above-mentioned fine protrusions 24 on the inner surface of the cylindrical body 14, the friction loss is reduced, and it is possible to increase the rising flow velocity of the air flowing through the flow path 23 of the cylindrical body 14. It is.

With the configuration as described above, the following effects (1) to (3) are achieved according to the present embodiment.
(1) The evaporating part 21 of the heat pipe 13 is immersed in the pool water 15 of the spent fuel storage pool 11, and the condensing part 22 of the heat pipe 13 is included in the cylindrical body 14, and the cylindrical body 14 and the condensing part An air flow path 23 is formed between the air passage 22 and the air passage 22. For this reason, when cooling the pool water 15 using the heat pipe 13 using the temperature difference between the pool water 15 of the spent fuel storage pool 11 and the air, the condensing part 22 and the cylindrical body 14 of the heat pipe 13 By generating an air upward flow due to the difference in air density in the flow path 23 between them, the amount of heat released from the condensing part 22 of the heat pipe 13 can be increased. As a result, the cooling effect of the pool water 15 using the heat pipe 13 is improved, the decay heat of the spent fuel A submerged in the pool water 15 is lost to the entire power source, and the pool water cooling and purification system 12 is activated. Even when it disappears, it can be suitably removed.

  (2) Since the vertical length L of the cylindrical body 14 is set to be twice or more the vertical length N of the condensing part 22 in the heat pipe 13, the upper portion of the flow path 23 in the cylindrical body 14. The density difference due to the temperature difference of the air between the region and the lower region becomes large, and the flow rate of the upward flow of air flowing through the flow path 23 can be increased. As a result, the amount of heat released from the condensing part 22 of the heat pipe 13 is increased, and the amount of heat removed from the pool water 15 in the spent fuel storage pool 11 and the decay heat of the spent fuel A can be increased. In addition, the condenser 22 and the cylindrical body 14 of the heat pipe 13 can be downsized.

  (3) Since a large number of fine protrusions 24 are formed substantially uniformly on the inner surface of the cylindrical body 14, the development of the boundary layer of air generated on the inner surface of the cylindrical body 14 by the fine protrusions 24 can be suppressed, and the cylindrical body The friction loss on the inner surface of 14 can be reduced. Also by this, the flow rate of the upward flow of the air flowing through the flow path 23 in the cylindrical body 14 can be increased, and the heat of the pool water 15 of the spent fuel storage pool 11 and the decay heat of the spent fuel A can be reduced. The amount of heat removal can be increased, and downsizing of the condensing part 22 and the cylindrical body 14 of the heat pipe 13 can be realized.

[B] Second Embodiment (FIG. 3)
FIG. 3A is a configuration diagram showing a second embodiment of the spent fuel storage facility 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 spent fuel storage facility 30 of the second embodiment differs from the first embodiment in that, in addition to the spent fuel storage pool 11, the pool water cooling and purification system 12, the heat pipe 13, and the tubular body 14, a thermoelectric A thermoelectric element 31 as a conversion means and a blower 32 as a blowing means are additionally provided.

The thermoelectric element 31 is installed on the surface of the spent fuel A submerged in the pool water 15 in the spent fuel storage pool 11, and generates electric power by the temperature difference between the surface of the spent fuel A and the pool water 15. Further, the blower 32 is disposed below the outer side of the cylindrical body 14, is driven by electric power from the thermoelectric element 31, forcibly blows air to the flow path 23 in the cylindrical body 14, and flows through the flow path 23. Increase the flow rate of the upward flow of air.
The thermoelectric element 31 should just be installed so that the upper surface or side surface of the spent fuel A may be contacted. For example, the cover 33 shown in FIG. One end of the cover 33 is closed, the cross section perpendicular to the axial direction is formed in a rectangular tube shape, and the thermoelectric element 31 is attached to the inner surface. There may be a plurality of thermoelectric elements 31. This cover is installed so as to cover the upper end of the spent fuel A. In addition, a hole 33a is provided in the closed side surface (upper surface in FIG. 3B) so as not to interfere with the handle of the spent fuel A. With such a configuration, the thermoelectric element 31 can be installed simply by hanging the cover with the thermoelectric element 31 on the spent fuel A using a fuel exchanger or the like. Further, since the cover 33 does not cover the handle of the spent fuel A, the subsequent operation is not hindered.
Further, a lid 33b may be provided in order to prevent the cover 33 from being lifted off due to an earthquake. The lid 33b is provided so as to cross the hole 33a, and is configured to freely rotate upward using, for example, a hinge. According to this configuration, when the cover 33 is installed, the lid 33b is lifted up and opened by the handle of the spent fuel A, and is closed by gravity when the handle passes. At the time of an earthquake, even if the cover 33 is lifted, the cover 33 b and the handle interfere with each other, so that the cover 33 does not come off.
Further, the cover 33 may be provided with a hanging ear so that it can be suspended by a fuel changer or the like, or may be installed using a dedicated jig.
Further, without using the cover 33, the thermoelectric element 31 may be simply suspended from the handle of the spent fuel A or the upper end of the side of the channel box and brought into contact with the surface of the spent fuel A.

  With the configuration as described above, according to the second embodiment, in addition to the same effects as the effects (1) to (3) of the first embodiment, the following effect (4) is achieved.

  (4) The thermoelectric element 31 is installed in the spent fuel A submerged in the spent fuel storage pool 11, and the blower 32 is operated using the electric power generated by the thermoelectric element 31, to the flow path 23 of the cylindrical body 14. Since air is forcibly blown from below the cylindrical body 14, the flow rate of the air rising flow that rises in the flow path 23 can be increased. As a result, the heat radiation effect by the condensing part 22 of the heat pipe 13 is promoted, the decay heat of the spent fuel A can be removed more effectively, and the condensing part 22 and the cylindrical body 14 of the heat pipe 13 can be reduced in size. Can be

[C] Third embodiment (FIG. 4)
FIG. 4 is a configuration diagram showing a third embodiment of the spent fuel storage facility according to the present invention. In the third embodiment, the same parts as those in the first and second embodiments are denoted by the same reference numerals, and the description is simplified or omitted.

  The spent fuel storage facility 40 of the third embodiment differs from the first embodiment in that, in addition to the spent fuel storage pool 11, the pool water cooling and purification system 12, the heat pipe 13, and the tubular body 14, a thermoelectric The element 31, the blower 32, and the duct 41 are additionally provided. Among these, the thermoelectric element 31 is the same as that of the second embodiment.

  The duct 41 extends from the outside of the tubular body 14 to the inside of the tubular body 14 through the outside of the lower end portion of the tubular body 14, and has an outlet 42 at the tip and an inlet 43 at the base end. Composed. The air outlet 42 is formed to open upward on the inside of the cylindrical body 14, and the introduction port 43 is opened to the outside of the cylindrical body 14.

  Inside the duct 41, the blower 32 is disposed near the introduction port 43. The blower 32 is driven by the electric power generated by the thermoelectric element 31, introduces air outside the cylindrical body 14 into the duct 41 from the inlet 43, and introduces the introduced air into the duct 14. The air is ejected upward from the air outlet 42 to the passage 23.

  Here, the air outlet 42 of the duct 41 is formed to have an opening area smaller than that of the inlet 43, and the air opening speed of the air discharged from the air outlet 42 is about 10 m / second or more. Is set. Since such high-speed air is ejected from the outlet 42 to the flow path 23 of the cylindrical body 14, the pressure in the flow path 23 decreases, so that the air at the outer lower portion of the cylindrical body 14 is in the cylindrical body 14. Will be aspirated. Since this sucked air has a flow rate several times the air flow rate ejected from the air outlet 42 of the duct 41, the flow rate of air flowing through the flow path 23 of the cylindrical body 14 can be extremely increased.

  With the configuration as described above, the fourth embodiment also provides the following effect (5) in addition to the same effects as the effects (1) to (3) of the first embodiment.

  (5) A duct 41 that extends from the outside of the tubular body 14 to the inside of the tubular body 14 through the outside of the lower end portion of the tubular body 14 is installed in the tubular body 14. In the duct 41, an air outlet 42 that opens upward inward of the cylindrical body 14 is formed at the distal end of the duct 41, and the blower 32 is disposed inside the proximal end of the duct 41 on the introduction port 43 side. The blower 32 is driven by electric power generated by the thermoelectric element 31 installed on the surface of the spent fuel A submerged in the pool water 15 in the spent fuel storage pool 11.

  Since the air blower 32 is driven as described above, the air outside the cylindrical body 14 is jetted upward from the air outlet 42 of the duct 41 to the flow path 23 of the cylindrical body 14. A large amount of air below the outside of the cylindrical body 14 is sucked into the flow path 23 by the jet pump action. As a result, the flow rate of the air upward flow flowing from below to above in the flow path 23 becomes extremely large, so that the heat dissipation effect of the condensing part 22 of the heat pipe 13 is remarkably improved, and the pool water in the spent fuel storage pool 11 Thus, the heat of 15 and the decay heat of the spent fuel A can be removed more suitably, and the condensing part 22 and the cylindrical body 14 of the heat pipe 13 can be reduced in size.

  As mentioned above, although this invention was demonstrated based on the said embodiment, this invention is not limited to this, A component may be variously deformed in the range which does not deviate from the summary, and it covers different embodiment. You may combine a component suitably.

  For example, as shown in FIG. 5, a plurality of swirl vanes 45 are arranged in the air outlet 42 of the duct 41 in the spent fuel storage facility 40 of the third embodiment along the circumferential direction of the air outlet 42. You may comprise so that the air ejected from the blower outlet 42 may be made into a swirl flow. Thereby, the air which flows through the flow path 23 of the cylindrical body 14 is stirred, and the heat dissipation effect in the condensing part 22 of the heat pipe 13 is further improved. Therefore, the heat removal of the pool water 15 of the spent fuel storage pool 11 and the decay heat of the spent fuel A can be further promoted, and the condensing part 22 and the cylindrical body 14 of the heat pipe 13 can be reduced in size. .

  Further, in the spent fuel storage facility 40 of the third embodiment, the blower 32 may be disposed not in the duct 41 but in the vicinity of the inlet 43 outside the duct 41.

10 Spent Fuel Storage Facility 11 Spent Fuel Storage Pool 12 Pool Water Cooling Purification System (Pool Water Cooling System)
13 Heat pipe 14 Tubular body 15 Pool water 17 Pump 19 Heat exchanger 21 Evaporating part 22 Condensing part 23 Channel 24 Fine protrusion 30 Spent fuel storage equipment 31 Thermoelectric element (thermoelectric conversion means)
32 Blower (Blower means)
33 Cover 33a Hole 33b Lid 40 Spent fuel storage equipment 41 Duct 42 Outlet 43 Inlet 45 Swivel blade A Spent fuel L, N Length

Claims (8)

A spent fuel storage pool that submerges spent fuel in pool water to remove decay heat of the spent fuel;
A spent fuel storage facility comprising: a pump and a heat exchanger; and a pool water cooling system for returning the pool water to the spent fuel storage pool by cooling the pool water by guiding the pool water to the heat exchanger by driving the pump;
A heat pipe in which an evaporating part is immersed in the pool water of the spent fuel storage pool, and a condensing part is positioned above the surface of the pool water;
A spent fuel storage facility comprising: a cylindrical body that encloses the condensing part of the heat pipe and in which a flow path for allowing air to flow is formed between the condensing part. The heat pipe condensing part is included in the lower part of the cylindrical body, and the vertical length of the cylindrical body is set to be twice or more the vertical length of the condensing part. Spent fuel storage equipment described in 1. The spent fuel storage facility according to claim 1 or 2, wherein fine protrusions are formed substantially uniformly on the inner surface of the cylindrical body. Thermoelectric conversion means installed on the surface of the spent fuel submerged in the pool water of the spent fuel storage pool and generating electric power; disposed outside and below the cylindrical body; and driven by electric power from the thermoelectric conversion means The spent fuel storage facility according to claim 1, further comprising a blowing unit that blows air into the cylindrical body. Thermoelectric conversion means installed on the surface of the spent fuel submerged in the pool water of the spent fuel storage pool to generate electric power, and from the outside of the tubular body through the outside of the lower end of the tubular body, A duct extending inwardly and having a blower opening at the tip opened above the inner side of the cylindrical body, and driven by electric power from the thermoelectric conversion means, air outside the cylindrical body The spent fuel storage facility according to any one of claims 1 to 3, further comprising a blowing means for guiding the air to the inside and upward of the cylindrical body from the outlet. 6. The spent fuel storage facility according to claim 5, wherein an opening area of the air outlet of the duct is set so that a flow velocity of air ejected from the air outlet is 10 m / second or more. The spent fuel storage facility according to claim 5 or 6, wherein swirl vanes using swirling air as a swirling flow are disposed at the outlet of the duct. The spent fuel storage facility according to any one of claims 5 to 7, wherein an air blowing means is disposed in the duct.

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