Cooling system for reactor pressure vessel support structure

Abstract

To allow for maintaining cooling performance even when temperature of the atmosphere in a reactor pressure vessel chamber becomes high using air-cooled pressure vessel cooling equipment so as to prevent deterioration of structural members such as a base, support legs, and surrounding concrete.SOLUTION: A cooling device for a support structure 4 supporting a reactor pressure vessel 1 on a base 8 is provided, the cooling device comprising a support housing 10 provided on the base having support legs 6 of the reactor pressure vessel installed thereon, and a cooling panel 3d provided at least on an upper surface of the base to supply and discharge cooling air to and from the support housing.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE An embodiment of the present invention relates to a cooling system for a support structure of a nuclear reactor pressure vessel. [Background technology]

[0002] For example, as shown in Fig. 9, a reactor pressure vessel (RPV) 1 of a high temperature gas reactor is placed on a pedestal 8 via support legs 6 in a reactor pressure vessel room 5 surrounded by a shielding wall 2. A pressure vessel cooling system (RCCS) 3 consisting of cooling panels 3a-3c arranged to cover the shielding wall 2 is installed in the reactor pressure vessel room 5, which is a high-temperature atmosphere. A coolant circulates inside each of the cooling panels 3a-3c to lower the internal temperature of the reactor pressure vessel room 5 and prevent the shielding wall 2, made of concrete, from becoming too hot.

[0003] The support structure 4 of the RPV 1 supports the loads of the RPV 1 and the core components installed inside the RPV 1, as well as the reactor internals, during normal operation and during earthquakes. The lower ends of the support legs 6 are welded to flanges and are installed on a base plate provided on a pedestal 8. This flange is fixed to an anchor plate embedded in the pedestal 8 and foundation bolts by screw fastening (not shown).

[0004] Concrete generally deteriorates at temperatures of 60 to 70°C or higher. Therefore, if the temperature of the RPV 1 increases and the supporting structure 4 becomes hot due to heat conduction from the RPV 1, the concrete base 8 in contact with the supporting structure 4 and the concrete around the base 8 will also become hot, which may reduce the strength of the structure.

[0005] Furthermore, when the temperature of the base portion 8 becomes high, the thermal stress load on the foundation bolt increases, and the bolt may break. Therefore, in order to maintain the integrity of the support structure 4 including the pedestal 8, it is necessary to cool the support structure 4 and the pedestal 8 of the RPV 1.

[0006] In a high-temperature gas-cooled reactor, helium gas heated to about 700 to 900°C circulates inside the reactor pressure vessel (RPV) 1, causing the core to reach an extremely high temperature. Although the RPV 1 is cooled by cooled helium gas, it is maintained at a high temperature of about 400°C during rated operation, and it is predicted that the temperature of the support structure 4 that supports the RPV 1 will also become high.

[0007] The reactor pressure vessel room 5 between the RPV 1 and the RCCS 3 is filled with air at atmospheric pressure, and since the inside becomes hot due to radiation and natural convection, the inside of the reactor pressure vessel room 5 is cooled by a coolant (water, gas, etc.) circulating inside the cooling panels 3a to 3c. When the coolant is air, the coolant is supplied from outside the reactor building 17 (see Figure 4) and, after cooling, is discharged outside the reactor building 17.

[0008] In this way, the decay heat of the core inside the RPV1 during rated operation and in the event of an abnormality or accident is received by the RCCS3 consisting of cooling panels 3a to 3c through heat transfer by radiation and natural convection, cooled by the coolant circulating inside, and finally removed. In addition, the RCCS 3 cools the shielding wall 2 to prevent deterioration due to high temperatures, and also removes heat from the support structure 4 of the RPV 1.

[0009] Although water or gases such as air can be used as a coolant, an air-cooled RCCS3 that uses air as a coolant utilizes the draft effect of the air that heats up inside the RCCS3. Compared to a water-cooled RCCS that uses a power source to force-circulate cooling water using a pump, it is possible to achieve passive circulation of cooling air without a power source, and has excellent characteristics for ensuring safety, which has become an issue of particular importance in the use of nuclear power in recent years, such as during power loss.

[0010] However, there may be cases where the cooling method for the support structure 4 using the cooling panels 3a to 3c does not function to sufficiently cool the support structure 4. For example, when the RPV 1 reaches a high temperature of 400° C. or more, it is expected that the cooling panels 3 a to 3 c will reach 200° C. or more due to convective heat transfer between the support structure 4 and the reactor pressure vessel room 5 .

[0011] At this time, the air in the reactor pressure vessel room 5 also becomes hot, making it difficult to cool the support structure 4 or causing it to be heated. Furthermore, the cooling panel 3a near the support structure 4 becomes hot, making it difficult to cool the support structure 4 through radiant heat transfer to the cooling panel 3a or causing it to be heated.

[0012] Therefore, it is necessary to take measures to cool the support structure 4. For example, in a light water reactor or the like, a simple solution to prevent a temperature rise at the contact point between the support structure 4 and the pedestal 8 is to extend the support legs 6 of the support structure 4 shown in Fig. 10 by the amount of the temperature rise.

[0013] However, in a high-temperature gas reactor, a problem occurs in that the air in the reactor pressure vessel chamber 5 becomes very hot, so even if the support legs 6 are extended, this does not solve the problem of the support structure 4 being heated in a high-temperature atmosphere. Therefore, a device for cooling the support structure 4 has been proposed to prevent a rise in temperature of the base of the reactor pressure vessel room.

[0014] FIG. 10 shows an example of a cooling device for a support structure 4 having a truncated cone-shaped support leg 6 installed in a light water reactor. Note that FIG. 10 shows an example of a reactor pressure vessel (RPV) 1 of a light water reactor. However, in the event of an accident or the like, the vicinity of the support structure 4 of a light water reactor can become very hot, just like a high temperature gas reactor, and a cooling device for the support structure 4 is therefore required.

[0015] 10, the cooling device of the support structure 4 is explained. A truncated cone-shaped support leg 6 is attached to the lower part of the side wall of the fuselage of the RPV 1. The lower end ring 6a of the support leg 6 is placed on a ring-shaped steel support base 4a that protrudes concentrically from the inner circumference of a cylindrical pedestal (base) 7, and is fixed by foundation bolts and nuts (not shown).

[0016] The cooling air is introduced into the reactor pressure vessel room 5 through the duct penetration hole 7a of the pedestal 7, rises below the support base 4a, and rises outside the support leg 6 through the ventilation opening 4b provided in the support base 4a.

[0017] In this way, the cooling air circulates inside the reactor pressure vessel chamber 5, thereby making it possible to cool the pedestal 7 and the support structure 4 consisting of the support legs 6 and the support base 4a, thereby lowering the temperature of the concrete-filled part of the pedestal 7 and preventing deterioration of the concrete. The cooling system of the above-mentioned support structure 4 is a typical structure of a light water reactor, and heat insulation construction work for the RPV 1 has been carried out. [Prior art documents] [Patent documents]

[0018] [Patent Document 1] Japanese Utility Model Application Publication No. 61-26197 Summary of the Invention [Problem to be solved by the invention]

[0019] Incidentally, in the high-temperature gas reactor shown in Figure 9, heat from the core is removed by cooling panels 3a to 3c of the RCCS 3 installed in the reactor pressure vessel room 5 inside the shielding wall 2 of the RPV 1, so insulation construction work as shown in Figure 10 is not carried out, and no facility for circulating cooling air inside the reactor pressure vessel room 5 is installed. Therefore, it is difficult to apply the cooling device for the support structure 4 in the light water reactor described above to a high temperature gas reactor.

[0020] In addition, the cooling device for the conventional supporting structure 4 has problems such as insufficient cooling capacity when the reactor pressure vessel room 5 becomes a high-temperature atmosphere, such as in a high-temperature gas reactor, and the cooling air used in the cooling device cannot be brought into the reactor pressure vessel room by air conditioning. These problems make it difficult to prevent deterioration of the concrete due to the rise in temperature of the pedestal 8 of the reactor pressure vessel room 5 caused by the rise in temperature of the supporting structure 4, and to prevent deterioration due to thermal stress of the foundation bolts and nuts at the contact points between the supporting structure 4 and the pedestal 8.

[0021] An embodiment of the present invention has been made to solve the above-mentioned problems, and has an object to provide a cooling device for a supporting structure of a reactor pressure vessel that maintains cooling capacity even when the inside of the reactor pressure vessel chamber becomes a high-temperature atmosphere, and prevents deterioration of structural materials such as the base and surrounding concrete. [Means for solving the problem]

[0022] In order to solve the above problems, the cooling device for the support structure of the reactor pressure vessel according to this embodiment includes: High-Temperature Gas-Cooled Reactor A cooling device for a support structure that supports a reactor pressure vessel on a base, the cooling device having a support housing provided on the base on which a support leg of the reactor pressure vessel is installed, and a cooling panel provided on at least an upper surface of the base for supplying and discharging cooling air to and from the support housing. The cooling air supplied to and discharged from the cooling panel is taken from the atmosphere outside the reactor building, and the cooling air heated inside the reactor pressure vessel is exhausted to the outside of the reactor building by natural convection. It is characterized by: Effect of the Invention

[0023] According to this embodiment, the air-cooled pressure vessel cooling equipment maintains cooling capacity even when the inside of the reactor pressure vessel room becomes hot or during a power loss, and prevents deterioration of the supporting structure and the structural materials in the vicinity thereof. [Brief description of the drawings]

[0024] [Figure 1] FIG. 2 is a cross-sectional configuration diagram of a cooling device for a support structure according to the first embodiment. [Diagram 2]FIG. 2 is an enlarged cross-sectional view of the cooling device for a support structure according to the first embodiment. [Diagram 3] FIG. 2 is a schematic diagram of a supporting housing according to the first embodiment. [Figure 4] FIG. 1 is a schematic diagram of a pressure vessel cooling system according to a first embodiment. [Diagram 5] FIG. 11 is a schematic diagram of a supporting housing according to a second embodiment. [Figure 6] FIG. 11 is an enlarged cross-sectional view of a cooling device for a support structure according to a third embodiment. [Figure 7] FIG. 13 is a cross-sectional configuration diagram of a cooling device for a support structure according to a fourth embodiment. [Figure 8] FIG. 13 is a cross-sectional configuration diagram of a cooling device for a support structure according to a modified example of the fourth embodiment. [Figure 9] Schematic diagram of a conventional pressure vessel cooling system. [Figure 10] FIG. 13 is a configuration diagram of a conventional cooling device for a support structure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a cooling device for a support structure of a reactor pressure vessel according to the present invention will be described with reference to the drawings.

[0026] [First embodiment] A cooling device for a support structure of a reactor pressure vessel according to a first embodiment will be described with reference to FIGS.

[0027] (composition) As shown in Figures 1 to 3, the cooling device for the support structure according to this embodiment is, for example, a support structure 4 for an RPV1 of a high-temperature gas reactor, in which a truncated cone-shaped support leg 6 is attached to a side wall of the body of the RPV1, and a lower end ring 6a of the support leg 6 is installed on a support housing 10 arranged in a ring shape on a concrete pedestal 8 in the reactor pressure vessel room 5.

[0028] Specifically, as shown in FIG. 2, the support housing 10 has a rectangular cross section and is fixed to a concrete base 8 together with a lower end ring 6a of the support leg 6 by a foundation stud bolt 9a and a nut 9b (see FIG. 2), and cools the contact points between the support leg 6 and the base 8. A cooling panel 3d, which is part of the pressure vessel cooling system (RCCS) 3, is installed on the upper surface of the base 8, and a partition plate 11 is provided inside the panel 3d so that cooling air can circulate.

[0029] As shown in FIG. 2, the front and back surfaces of the support legs 6, the front surface of the support housing 10, the front surface of the cooling panel 3d, and the foundation stud bolts 9a and nuts 9b are covered with a thermal insulating material 15 to reduce the effects of the high-temperature atmosphere in the reactor pressure vessel chamber 5.

[0030] (Configuration of the supporting housing) As shown in FIG. 3, the support housing 10 has an intake port 12 through which cooling air is supplied from the cooling panel 3d and an exhaust port 13 through which the cooling air inside the support housing 10 is exhausted, and a partition plate 14 is provided inside the support housing 10 for circulating the cooling air. The cooling panel 3d installed on the base portion 8 is a part of the cooling panel of the air-cooled RCCS 3, and as shown in FIG.

[0031] (action) Next, the operation of the cooling device for the support structure 4 configured as above will be described. First, as shown in FIG. 4, the RCCS 3 draws in the atmosphere outside the reactor building 17 as cooling air, passes the air through the flow paths in the cooling panel 3d and the supporting housing 10 in the directions indicated by arrows A0 to A7 (see FIGS. 2 to 4), and exhausts the heated cooling air to the outside of the reactor building 17.

[0032] In the supporting housing 10, the cooling air flowing in from the cooling panel 3d through the intake port 12 flows through the supporting housing 10 in the directions indicated by the arrows A2→A3→A4→A5 as shown in Fig. 3, and rises near the partition plate 14. The cooling air then passes through the exhaust port 13 and is guided to the cooling panel 3d as indicated by the flow of the arrow A5, and is discharged to the cooling panel 3d as indicated by the flow of the arrow A6.

[0033] 4 shows only the left side portion of the cooling panel 3d and the supporting housing 10 of the RPV 1, and the right side portion is omitted. In addition, in the example of Figures 1 to 3, the support leg 6 is frusto-conical, while in the example of Figure 4 it is cylindrical or leg-shaped, but the cooling device according to this embodiment can be applied to either type of support leg.

[0034] Furthermore, in this embodiment, the cooling panel 3d is arranged across the side wall of the reactor pressure vessel chamber 5 and the pedestal portion 8, but they may be separated and a cooling panel that cools only the pedestal portion 8 may be provided (not shown).

[0035] (effect) As described above, according to the first embodiment, the cooling device using the cooling panel 3d through which cooling air circulates and the supporting housing 10 can prevent temperature rise in the supporting structure 4 of the RPV 1, the main body of the supporting housing 10, the foundation stud bolts 9a and nuts 9b for fixing, the base 8 with which the supporting housing 10 is in contact, and structures in the vicinity thereof. This makes it possible to solve the thermal stress problem of the foundation stud bolts 9a and nuts 9b of the support structure 4 of the RPV 1 and the deterioration problem of the concrete.

[0036] Furthermore, by using the air-cooled RCCS 3 to supply and exhaust the cooling air circulating in the support casing 10, the cooling capacity of the cooling air can be maintained even in the high temperature atmosphere of the reactor pressure vessel room 5 where high temperature conditions are predicted, and the cooling device can have a passive cooling function even in the event of a power loss, thereby improving the safety of the nuclear power plant. In the example of Figures 1 to 3, the support leg 6 is described as having a truncated cone shape, but the present invention is not limited to this, and the cooling device according to this embodiment can also be applied to a cylindrical or leg-shaped one as shown in Figure 4.

[0037] The shapes and arrangements of the supporting housing 10 and the cooling panels 3d can also be changed as appropriate, for example, the cross section of the supporting housing 10 can be other than rectangular, and the mounting means to the base part 8 can be other fixing means than bolts and nuts. Furthermore, the number and arrangement of the cooling panels in the reactor pressure vessel chamber 5 can also be changed as appropriate.

[0038] [Second embodiment] A cooling device for a support structure of a reactor pressure vessel according to a second embodiment will be described with reference to FIG. In the second embodiment, in order to reinforce the supporting housing 10, a vertical rib 18 extending in the radial direction (vertical direction) is provided inside the supporting housing 10.

[0039] The supporting housing 10 is required to be strong enough to support the load of the RPV 1, and the vertical ribs 18 increase the rigidity of the supporting housing 10, making it possible to improve the strength of the supporting housing 10 and the efficiency of heat exchange with the cooling air.

[0040] [Third embodiment] A cooling device for a support structure of a reactor pressure vessel according to a third embodiment will be described with reference to FIG. In the third embodiment, a metal plate 19 is installed on the inner surface of a space surrounding the support housing 10 and the lower end ring 6a of the support leg 6 that contacts the support housing 10. The metal plate 19 contacts the support leg 6 that constitutes the support structure 4, and also contacts the cooling panel 3d provided on the base part 8.

[0041] As a result, the support structure 4 has a cooling function by the cooling panel 3d through the metal plate 19. Furthermore, the metal plate 19 prevents the flow of the high-temperature atmosphere in the reactor pressure vessel chamber 5 from entering the periphery of the grounding point between the support leg 6 and the support housing 10.

[0042] Further, heat insulating material 15 is laid on the front and back surfaces of the support structure 4, the front surface of the support housing 10, and the front surface of the cooling panel 3d, where the metal plate 19 comes into contact with the high-temperature atmosphere, to prevent heat from entering from the high-temperature atmosphere.

[0043] [Fourth embodiment] A cooling device for a support structure of a reactor pressure vessel according to a fourth embodiment will be described with reference to FIG.

[0044] 7, in the fourth embodiment, a cooling panel 3e is provided along a side wall 23 of the base part 8 facing the lower part of the RPV 1 to remove radiant heat from the lower part of the RPV 1. The cooling panel 3e takes in cooling air from an intake port 20 of the supporting housing 10, circulates the air through the cooling panel 3e, and then exhausts the air from an exhaust port 21 to the supporting housing 10. This allows the passive cooling capacity of the air-cooled RCCS 3 to be used to cool the concrete side wall 23 of the lower chamber of the RPV 1, preventing deterioration of the concrete due to high temperatures.

[0045] (Modification) In this modification, as shown in FIG. 8, a cooling panel 3f extending downwardly of the RPV 1 is added to the cooling panel 3e shown in FIG.

[0046] The lower part of the reactor pressure vessel room 5 is heated to high temperatures by radiant heat from the lower part of the RPV 1 and by convective heat transfer due to natural convection. Therefore, in addition to the cooling panel 3e for cooling the side wall 23, a cooling panel 3f extending to the lower part of the RPV 1 is provided.

[0047] This allows the radiant heat to be efficiently received at a position close to the RPV 1, suppressing a temperature rise in the side wall 23 facing the lower part of the RPV 1, and also reducing the installation area of ​​the cooling panel 3e.

[0048] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0049] Reference Signs List 1... Reactor pressure vessel (RPV), 2... Shielding wall, 3... Pressure vessel cooling system (RCCS), 3a to 3f... Cooling panel, 4... Support structure, 4a... Support stand, 5... Reactor pressure vessel room, 6... Support leg, 6a... Bottom ring, 7... Pedestal, 8... Base, 9a... Foundation stud bolt, 9b... Nut, 10... Support housing, 11... Partition plate, 12, 20... Intake port, 13, 21... Exhaust port, 14... Partition plate, 15... Insulation material, 17... Reactor building, 18... Vertical rib, 19... Metal plate, 23... Side wall

Claims

1. A cooling device for a support structure that supports a reactor pressure vessel of a high temperature gas reactor on a base, comprising: the cooling device includes a support housing provided on a pedestal on which a support leg of the reactor pressure vessel is installed, and a cooling panel provided on at least an upper surface of the pedestal for supplying and discharging cooling air to and from the support housing, A cooling device for a supporting structure of a reactor pressure vessel, characterized in that the cooling air supplied to and discharged from the cooling panel is the atmosphere outside the reactor building, and the cooling air heated inside the reactor pressure vessel is exhausted to the outside of the reactor building by natural convection.

2. 2. The cooling system for a support structure of a reactor pressure vessel according to claim 1, wherein said cooling panel has a partition plate for circulating said cooling air.

3. 3. The cooling device for a support structure of a reactor pressure vessel according to claim 1, wherein the support housing has an intake port through which cooling air is supplied, an exhaust port through which the cooling air is discharged, and a partition plate for circulating the cooling air therein.

4. 4. The cooling system for a support structure of a reactor pressure vessel according to claim 1, wherein a heat insulating material is provided around said support legs, said cooling panel and said support housing.

5. 5. The cooling device for a support structure of a reactor pressure vessel according to claim 1, wherein a metal plate is provided on an inner surface of a cavity surrounding said support casing and said lower end ring of said support leg.

6. 6. The cooling system for a support structure of a reactor pressure vessel according to claim 1, further comprising a cooling panel provided on a side wall of the base portion facing the lower portion of the reactor pressure vessel.

7. 7. The cooling system for a support structure of a reactor pressure vessel according to claim 6, wherein the cooling panel provided on the side wall of said base portion is provided with a cooling panel extending to a lower portion of said reactor pressure vessel.

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