JP4469520B2 - Reactor piping seal device, its handling tool, and reactor piping seal method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is an atom suitable for reducing the radiation exposure of workers during maintenance work of a reactor internal structure of a boiling water reactor (hereinafter referred to as BWR), for example, when performing shroud replacement work. The present invention relates to an in-reactor piping sealing device, a handling tool for the same, and a reactor in-pipe sealing method.
[0002]
[Prior art]
Conventionally, the BWR employs a so-called jet pump system in which a recirculation pump installed outside the reactor pressure vessel and a jet pump provided inside the reactor pressure vessel are combined in order to increase the power density. Hereinafter, a BWR employing this jet pump system will be described with reference to FIGS.
[0003]
FIG. 7 is a longitudinal sectional view showing the overall configuration of the reactor pressure vessel. A core shroud 2 is disposed in the reactor pressure vessel 1, and the core shroud 2 is supported by a shroud support cylinder 3. The shroud support cylinder 3 is supported on the bottom of the reactor pressure vessel 1 by a shroud support leg 4. An upper lattice plate 5 is provided on the upper portion of the core shroud 2, and a core support plate 6 is provided on the lower portion. A jet pump 7 is provided on the outer peripheral side of the core shroud 2, and this jet pump 7 is composed of a jet pump diffuser 7a, a jet pump riser pipe 7b, and a jet pump inlet mixer 7c. A baffle plate 8 is provided below the jet pump 7 over the entire circumference of the annulus portion constituted by the reactor pressure vessel 1 and the core shroud 2.
[0004]
A fuel assembly 10 is provided in the core shroud 2 so as to be sandwiched between the upper lattice plate 5 and the core support plate 6, and a control rod 9 for controlling the reactor output is provided between the fuel assemblies 10. It is provided so that it can be inserted and removed. When the reactor power is increased, the control rod 9 is pulled out. The pulled-out control rod 9 is stored in a cylindrical control rod guide tube 11 provided below the fuel assembly 10.
[0005]
On the other hand, above the core shroud 2, devices such as a core spray pipe 12, a core sparger 13, a steam dryer 15, a steam / water separator / shroud head 16, and the like are provided. It will be described later.
[0006]
In addition, the structure shown with the code | symbol 17 is the upper cover of the reactor pressure vessel 1, and these reactor pressure vessels 1 and the upper cover 17 are installed in the space 19 in the reactor containment vessel which is not shown in figure. The control rod 9 is inserted into and removed from the fuel assembly 10 by a control rod drive mechanism (hereinafter referred to as CRD) 20, and the CRD 20 is accommodated in a control rod drive mechanism housing (hereinafter referred to as CRD housing) 21. . A coolant 23 is injected into the reactor pressure vessel 1 and guided into the core shroud 2 to cool the core 24 composed of the fuel assemblies 10 and the control rods 9.
[0007]
The coolant 23 is guided into the reactor pressure vessel 1 by the water supply nozzle 22, descends outside the core shroud 2, passes through the shroud support legs 4, and ascends the core 24. At that time, the temperature is raised by the nuclear reaction heat of the core 24 and a two-phase flow state of water and steam is obtained. The coolant 23 in a two-phase flow state flows into the steam / water separator / shroud head 16 installed above the core 24, where it is separated into water and steam. Among these, the steam is introduced into the steam dryer 15 installed above the steam / water separator / shroud head 16 and becomes dry steam.
[0008]
The dry steam is transferred to the turbine (not shown) via the main steam nozzle 14 connected to the reactor pressure vessel 1 and is used for power generation. On the other hand, the separated water flows through a so-called downcomer portion of the annulus portion between the reactor pressure vessel 1 and the core shroud 2 and again flows into the lower portion of the core 24 from between the shroud support legs 4.
[0009]
A plurality of jet pumps 7 are installed at equal intervals in the circumferential direction in the downcomer portion, and a recirculation pump (not shown) is installed outside the reactor pressure vessel 1. , And a recirculation pipe connecting both of them constitutes a recirculation system. Then, driving water is supplied to the jet pump 7 by the recirculation pump, and the coolant 23 is forcedly circulated in the core 24 by the action of the jet pump 7.
[0010]
The core spare purger 13 is installed in order to inject water of a suppression pool (not shown) into the core 24 so as to prevent a coolant loss accident that may occur due to breakage of the recirculation pipe. The core spare purger 13 is circumferentially installed on the inner surface of the upper trunk above the upper end of the fuel assembly 10 so that cooling water can be uniformly injected into the core 24.
[0011]
This core space purger 13 is composed of semicircular pipes, and two are installed per system at a position of 180 degrees, and four cores are installed in the core shroud 2 for safety design. Has been. Further, the core spare purger 13 is fixed by a bracket (not shown) so that the outer circumferential portion of the pipe is in contact with the inner surface of the upper portion of the core shroud 2. Further, the inner diameter of the upper ring of the core shroud 2 is smaller than the outer diameter of the core spare purger 13.
[0012]
On the other hand, the jet pump 7 is used under severe conditions compared to other devices in order to give a large discharge pressure to a large amount of coolant and forcibly circulate it. Therefore, a large load acts on each component member.
[0013]
In particular, as shown in an enlarged view of the main part in FIG. 8, severe stress acts on the riser brace 40 that supports the jet pump riser pipe 7b in the middle thereof.
[0014]
The jet pump 7 has a jet pump riser pipe 7 b fixed inside the reactor pressure vessel 1, and an end thereof is connected to a recirculation inlet nozzle 33. A part of the coolant 23 existing in the reactor pressure vessel 1 is extracted into the above-mentioned recirculation system, and the driving water for the jet pump 7 is passed from the recirculation inlet nozzle 33 of the recirculation pump through the jet pump riser pipe 7b. It will be used as. A pair of elbows 35a, 35b is connected to the upper part of the jet pump riser pipe 7b via a transition piece 34.
[0015]
A pair of inlet throats 37a and 37b are connected to these elbows 35a and 35b via a pair of mixing nozzles 36a and 36b, respectively. Diffusers 38a and 38b are connected to the pair of inlet throats 37a and 37b, respectively.
[0016]
Then, a part of the coolant 23 supplied as drive water is injected by the mixing nozzles 36a and 36b through the recirculation system, and the coolant 23 is taken up from the periphery at that time. These driving water and the entrained coolant 23 are mixed inside the inlet throats 37a and 37b, and then the hydrostatic head is recovered by the diffusers 38a and 38b.
[0017]
By the way, in the jet pump 7, fluid vibration is generated by the flow of the coolant 23 fed from the recirculation pump. In order to cope with this fluid vibration, the lower end of the jet pump riser pipe 7b is welded to the recirculation inlet nozzle 33 as described above, and the upper end is fixed to the reactor pressure vessel 1 via the riser brace 40. .
[0018]
In addition, the inlet throats 37a and 37b are mechanically connected to the transition piece 34 through the mixing nozzles 36a and 36b and the vents as described above, and the lower ends thereof are inserted into the upper ends of the diffusers 38a and 38b. Has been. Thus, both the jet pump riser pipe 7b and the inlet throats 37a and 37b are configured to sufficiently cope with fluid vibration.
[0019]
Next, the configuration above the mixing nozzles 36a and 36b will be described. A pair of ears 41 are formed on both sides of the transition piece 34, respectively, and these ears 41 protrude upward and are located inside the upper end. A groove portion 42 is formed. Both ends of a pair of jet pump beams 43 having a rectangular cross section that increases along the central portion in the longitudinal direction are fitted and fixed to the groove 42.
[0020]
A screw hole (not shown) is formed in the center of the jet pump beam 43 in the vertical direction, and a head bolt 44 is screwed into the screw hole. A hexagon head is formed at the upper end of the head bolt 44, and a semi-round head is formed at the lower end.
[0021]
On the other hand, although not shown, the elbows 35a and 35b are formed with a pedestal portion having a horizontal upper end surface, and a counterbore hole (not shown) is formed in the pedestal portion. A semi-round head of the head bolt 44 is fitted into the counterbore through a spherical washer.
[0022]
Since the inlet throats 37a and 37b are not fixed to the reactor pressure vessel 1, the inflow water pressure of the driving water supplied via the jet pump riser pipe 7b acts on the upper end portions and the elbows 35a and 35b.
[0023]
In addition, a reaction force such as the ejection pressure of driving water ejected from the nozzle (not shown) connected to the other end of the elbows 35a and 35b into the diffusers 38a and 38b acts upward. A head bolt 44 is screwed into the jet pump beam 43 to counter this load.
[0024]
In addition, since the ear | edge part 41 is being fixed, if the head bolt 44 is rotated, it will move to the upper direction of the jet pump beam 43, and the both ends will be in the state contact | abutted on the upper wall surface of the groove part 42. FIG. As a result, an upward load is received.
[0025]
On the contrary, a downward load is applied to the upper ends of the elbows 35a and 35b via the head bolt 44, and the magnitude thereof is determined by the upward load due to the reaction force of the driving water. A keeper (not shown) is detachably fitted to the hexagon head of the head bolt 44. The keeper is fixed to a support plate not designated by spot welding. This support plate has a rectangular shape and is fixed to the upper surface of the jet pump beam 43 by two bolts.
[0026]
The inlet throats 37a and 37b are attached to a riser blanket 45 fixed to the jet pump riser pipe 7b. The diffusers 38 a and 38 b are fixed to a baffle plate 46 welded to the reactor pressure vessel 1.
[0027]
The riser brace 40 controls fluid vibration during operation of the reactor generated in the jet pump riser pipe 7b, and between the reactor pressure vessel 1 made of carbon steel and the jet pump riser pipe 7b made of austenitic stainless steel. Absorbs the difference in thermal expansion. Therefore, during the operation of the nuclear reactor, the reactor is in a deformed state while absorbing the above thermal expansion difference.
[0028]
By the way, it is important to measure the flow rate of the jet pump during normal operation when controlling the output of the nuclear power plant. For this reason, measurement pipes 39 are provided at the upper and lower portions of the diffusers 38a and 38b, and the diffuser during operation is operated. The static pressure difference between the upper and lower portions of 38a and 38b is measured, and the jet pump flow rate is calculated from the measured value and the calibration value measured before using the plant.
[0029]
The measurement pipe 39 is welded to the static holes in the upper and lower portions of the diffusers 38a and 38b, is welded and supported by a support 47 fixed to the diffusers 38a and 38b, and is further disposed under the jet pump 7 for jet pump measurement. It is connected to the piping outside the reactor through a nozzle.
[0030]
Two jet pump measurement nozzles are provided at symmetrical positions in the reactor pressure vessel 1. The jet pump 7 having such a configuration is used under severe conditions compared to other devices due to the flow of driving water fed from the recirculation pump. For this reason, a large load acts on each member, it is influenced by fluid vibration, severe stress acts on it, and therefore it is sufficiently predicted that pipe breakage will occur.
[0031]
On the other hand, when a metal material such as stainless steel having a high carbon content that constitutes the core shroud 2 is placed in high-temperature water, stress corrosion cracking (hereinafter referred to as IGSCC) occurs in the welded portion and the welded heat affected zone in the vicinity thereof. It is generally known to occur. This IGSCC is known to occur under conditions where three causes of material, stress and environment are superimposed. As a material factor, chromium (Cr) carbide folds out to the grain boundary, and a Cr-deficient layer with poor corrosion resistance is formed around it, and as a result, the material is made sensitive by welding and processing. The tensile residual stress remaining in the substrate is increased. Moreover, as an environmental factor, the amount of dissolved oxygen etc. which exist in high temperature water are raised. IGSCC can be prevented from occurring by removing one generation factor from the three generation factors of material, stress and environment.
[0032]
The core shroud 2 is a stainless steel member formed into a cylindrical structure by circumferential welding and vertical welding. If the core shroud 2 has a high carbon content in stainless steel, cracks due to stress corrosion cracking or the like may occur at or near the weld. Reactors generally have triple, quadruple or more multiple protection measures in place to ensure safety. If an event such as a crack occurs in the core shroud 2 of the nuclear reactor, it is necessary to repair or replace the core shroud 2 for the safety of the nuclear reactor. In addition, when a malfunction occurs in the reactor internal structure installed in the core shroud 2 as well, it is necessary to repair or replace it.
[0033]
When such an event occurs, for example, a method for repairing the welded portion of the core shroud is disclosed in Japanese Patent Laid-Open No. 5-323078. This publication discloses a first procedure for inspecting a welded portion from the surface of the core shroud 2 by an ultrasonic flaw detection test apparatus, and a second procedure for repairing the cracked portion when a cracked portion is found by the inspection. And a method for repairing a core shroud weld having a third procedure for performing a surface modification process on a post-processing portion of the repair processing.
[0034]
[Problems to be solved by the invention]
However, the core shroud of a nuclear reactor that has been used for a long period of time is embrittled by neutron irradiation from the core, and the core shroud that has been welded may cause finer cracks around the weld metal (welded part). Therefore, it is difficult to repair the core shroud by welding, and therefore there is a need for long working hours. Furthermore, the most desirable method for reactor safety is to replace a failed reactor internal structure or core shroud with a new structure or core shroud. However, it is more difficult to remove a structure or core shroud installed in the reactor and install a new structure or core shroud compared to repair, so when replacing the structure or core shroud Therefore, it is inevitable to work for a long time in a high radiation environment in a nuclear reactor, which is not preferable for safety management of workers.
[0035]
The present invention has been made in consideration of the above-described circumstances, and an annulus portion formed between the reactor pressure vessel and the core shroud when repairing or replacing the structure in the reactor pressure vessel or the core shroud. The reactor piping seal device and its device are designed to shield the radiation emitted from the reactor pressure vessel, etc. by this water, so that workers can work safely even if they enter the reactor. The object is to provide a handling tool and a method for sealing pipes in a nuclear reactor.
[0036]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is directed to an opening of an in-reactor pipe provided in an annulus portion constituted by a reactor pressure vessel and a core shroud welded and fixed to the inner bottom portion of the reactor pressure vessel. In the reactor piping seal device installed in the reactor part, a fixed part inserted into the opening of the reactor pipe, a shaft provided in the fixed part, a moving part inserted through the shaft, and this movement A seal portion interposed between the portion and the fixed portion, a nut screwed to the shaft, and the moving portion Near the outer periphery of the Provided in Grip the handling tool And a flange portion.
[0037]
Further, the invention according to claim 2 is the in-reactor piping seal device according to claim 1, wherein the brim portion Unite with A stopper having an outer diameter larger than the inner diameter of the opening; Is a thing .
[0038]
The invention described in claim 3 Claims 1 and 2 A fixed claw that engages with the flange portion of the piping seal device in the nuclear reactor, a moving claw, and a movable shaft that drives the moving claw to engage with the flange portion. Is a thing .
[0039]
According to a fourth aspect of the present invention, in the handling tool of the in-reactor piping seal device according to the third aspect, the movable shaft is screwed through a thread groove, and the inner shaft is rotated. The moving claw is driven.
[0040]
The invention according to claim 5 is a first procedure for carrying out a part of the structure provided in the reactor pressure vessel to the outside of the reactor pressure vessel, and the reactor pressure vessel and the bottom portion of the reactor pressure vessel. The opening of the reactor internal pipe provided in the annulus composed of the core shroud welded to Using the sealing device according to claim 1 or 2 and the handling tool according to claims 3 to 4 A second procedure for sealing, and a third procedure for filling the annulus with water.
[0041]
According to a sixth aspect of the present invention, there is provided a first procedure for carrying out a part of the structure provided in the reactor pressure vessel to the outside of the reactor pressure vessel, and a core fixed by welding to the bottom of the reactor pressure vessel. A second procedure for removing the shroud, a third procedure for carrying a new core shroud into the reactor pressure vessel and welding and fixing it to the bottom of the reactor pressure vessel, the reactor pressure vessel and the reactor Opening of the reactor piping provided in the annulus composed of the core shroud welded to the bottom of the pressure vessel Using the sealing device according to claim 1 or 2 and the handling tool according to claims 3 to 4 A fourth procedure for sealing, and a fifth procedure for filling the annulus with water.
[0042]
In the invention according to claim 1 configured as described above, Since the handling tool is engaged with the flange portion provided near the outer periphery of the moving part of the sealing device and the outside of the sealing device can be gripped almost entirely, the handling operation is facilitated and the remote operation is facilitated. It can be handled by operation. That is, At the opening of the reactor piping, Depending on the handling tool By rotating the nut, the moving part is pushed toward the fixed part, and the seal part sandwiched between the moving part and the fixed part is brought into close contact with the pipe in the reactor. Accordingly, water leaking into the reactor piping is eliminated, and water shielding is formed by applying water to the annulus formed outside the core shroud. According to this water shielding, the radiation exposure can be greatly reduced, so that workers can work safely in the reactor for a long time. Moreover, since the moving part does not protrude inward from the end of the piping opening in the reactor, the safety and reliability of the work can be improved without hindering the work in the annulus part. Since the seal part is sandwiched between the fixed part and the moving part and can be replaced, it is sufficient to replace the seal part even if the seal part is worn, and it is not necessary to replace the entire reactor piping seal device. Economical.
[0043]
The stopper, which is a constituent element of the invention described in claim 2, has an outer diameter larger than the inner diameter of the reactor pipe opening, and is brought into contact with the opening. Therefore, the reactor piping seal device can be prevented from entering the reactor piping.
[0044]
The fixing claw which is a component of the invention described in claim 3 is engaged with the flange portion of the invention described in claim 1 or 2. The movable shaft drives the moving claw and engages with the flange portion. In this way, the reactor piping seal device can be gripped by remote operation without dropping. Therefore, the seal member can be reliably sealed in the vicinity of the opening of the reactor internal pipe, and work safety and reliability can be improved.
[0045]
The movable shaft which is a constituent element of the invention described in claim 4 has a double cylindrical structure screwed through a thread groove, and drives the moving claw by rotating the inner shaft. Therefore, the moving claw can be easily engaged with the collar portion with a smaller load than when the moving claw is driven by moving the movable shaft directly in the vertical direction, for example.
[0046]
In the invention according to claim 5, it is possible to access the annulus portion in the reactor pressure vessel by the first procedure, and by the second procedure. Easily and safely without dropping the sealing device It is possible to seal the reactor internal pipe, and even if water is applied to the annulus part, water is not leaked outside the annulus part via the reactor internal pipe. Furthermore, it becomes possible to form a water shield according to the third procedure, and repair or replacement of the reactor internal structure and the shroud can be performed safely and for a long time while shielding the radiation.
[0047]
According to the sixth aspect of the present invention, it is possible to access the annulus portion in the reactor pressure vessel by the first procedure, and the core shroud that needs to be replaced is carried out by the second procedure. A new core shroud will be installed. When the third procedure is completed, the annulus portion is formed again. That is, since a new core shroud is welded, it is possible to fill the annulus with water without leaking from the bottom of the annulus to the inside of the core shroud. In the fourth procedure, Easily and safely without dropping the sealing device It is possible to seal the reactor internal pipe, and even if water is applied to the annulus part, water is not leaked outside the annulus part via the reactor internal pipe. Further, according to the fifth procedure, it becomes possible to form a water shield, and the repair work after the shroud replacement can be carried out safely and for a long time while shielding the radiation.
[0048]
DETAILED DESCRIPTION OF THE INVENTION
First and second embodiments of an in-reactor piping seal device according to the present invention will be described with reference to FIGS. 1 and 2. (Corresponding to Claims 1 and 2)
FIG. 1 is a cross-sectional view of an in-reactor piping seal device according to the first and second embodiments. FIG. 2 is an enlarged cross-sectional view of the reactor piping seal apparatus according to the first and second embodiments installed in the core spray system piping 12.
[0049]
In FIG. 1, an in-reactor piping seal device 50 is incorporated in the opening of the core spray system piping 12. This shows a state where water is shielded by applying water 48 to an annulus formed between the reactor pressure vessel 1 and the core shroud 2. In addition to the water 48, a shield 51 made of metal (lead) is also installed in the annulus. Since the metal shield 51 is heavy and difficult to install, the gap between the annulus portions is narrowed, resulting in poor workability.
[0050]
In FIG. 2 of the enlarged sectional view, reference numeral 52 denotes a seal member, It is a fixed part Fixing bracket 53 and It is a moving part It is assembled so as to be sandwiched between the movable fittings 54. A shaft 55 is integrally formed in the central portion of the fixing metal 53, and a moving metal 54 and a tightening nut 56 are incorporated in the shaft 55. By rotating the tightening nut 56, the sealing member 52 expands and contracts, and a mechanical sealing effect can be obtained. Since the seal member 52 is sandwiched between the fixed metal 53 and the movable metal 54, it can be exchanged. Therefore, even when the seal member 52 is worn or damaged, it is not necessary to replace the entire reactor piping seal device 50, and the reactor piping seal device 50 can be provided for a long period of time.
[0051]
Further, a flange portion 57 for gripping the sealing device 50 according to the first and second embodiments is provided outside the movable metal fitting 54, and can be freely attached and detached remotely by a handling tool described later. .
[0052]
Furthermore, in the second embodiment, a stopper 58 is provided integrally with the flange portion 57. Since the outer diameter of the stopper 58 is larger than the inner diameter of the opening of the core spray pipe 12, the reactor pipe seal device 50 can be prevented from entering the core spray pipe 12.
[0053]
The in-reactor pipe sealing device 50 is attached so as not to protrude from the opening of the core spray pipe 12 in order to expand and contract the seal member 52 by moving the moving fitting 54 toward the inside of the pipe from the opening of the core spray pipe 12. be able to. Furthermore, the fixed metal fitting 53 and the moving metal fitting 54 are formed in a convex shape toward the inside of the pipe, that is, a concave shape when viewed from the outside of the pipe. It is possible to prevent the attached nut 56 from protruding from the opening of the core spray pipe 12 to the annulus, and to have a structure that does not interfere with other operations performed at the annulus.
[0054]
A first embodiment of a handling tool for a reactor pipe sealing device according to the present invention will be described with reference to FIGS. 3 (a) and 3 (b) to FIG. (Corresponding to claims 3 and 4)
FIG. 3A is a front view of the handling tool of the in-reactor piping seal device according to the first embodiment. FIG. 3B is a side view thereof.
[0055]
3A and 3B, the handling tool 59 has a moving claw 61 that is driven up and down by two fixed claws 60 and a movable shaft 62. Further, a handle 63 is provided at the upper end of the movable shaft 62 in order to easily rotate the movable shaft 62. The movable shaft 62 has a double structure, and the inner movable shaft 62a and the outer movable shaft 62b are fitted with each other having a screw structure. The fixed claw 60 is provided at the lower end portion, and the fixed claw 60 is structured to engage with the inside of the flange portion 57 of the in-reactor piping seal device 50. At the time of remote operation, these fixed claws 60 are first engaged with the brim portion 57, and then the inner movable shaft 62a is moved up and down by rotating with the handle 63, and the movable claws 61 are interlocked to engage with the brim portion 57. By doing so, the reactor piping seal device 50 can be gripped.
[0056]
FIGS. 4A and 4B are a front view and a side view, respectively, showing a ratchet wrench for tightening or loosening the tightening nut 56 of the reactor piping seal device 50.
[0057]
4 (a) and 4 (b), the ratchet wrench 64 has a pole 66 at the upper portion thereof, and this pole 66 is attached by a fastening bolt 67. In addition, a socket portion 65 is provided at the lower portion of the ratchet wrench 64 and engages with the tightening nut 56 of the reactor piping seal device 50. The ratchet wrench 64 as shown in FIGS. 4 (a) and 4 (b) is not limited to the ratchet wrench 64 as long as it can be tightened and loosened by engaging with the tightening nut 56. When installed in the opening of the in-reactor piping, since an operation at the annulus formed by the reactor pressure vessel 1 and the core shroud 2 is required, a ratchet wrench 64 as illustrated is preferable.
[0058]
FIG. 5 is a longitudinal sectional view showing a state in which the socket portion 65 of the ratchet wrench 64 is set on the tightening nut 56 while the handling tool 59 is engaged with the in-reactor piping seal device 50. It is not always necessary to set the ratchet wrench 64 to the tightening nut 56 via the handling tool 59. However, by attaching the handling tool 59 when the tightening nut 56 is tightened or loosened, the tightening or loosening operation becomes easy. For example, in the tightening operation, the seal member 52 is not yet tightened inside the pipe, and there is a play between the in-reactor pipe seal device 50 and the inside of the pipe. Therefore, stability is lacking when trying to engage the ratchet wrench 64 with the tightening nut 56. After the reactor piping seal device 50 is inserted into the reactor piping by the handling tool 59, the reactor piping sealing device 50 can be stably supported if the handling tool 59 is mounted as it is, and the annulus. Also, it is possible to prevent the nut from dropping out, and the tightening operation of the tightening nut 56 by the ratchet wrench 64 is facilitated.
[0059]
On the other hand, in the case of the loosening operation, if the handling tool 59 is engaged with the reactor piping seal device 50 before the ratchet wrench 64 is loosened, the handling tool 59 is attached after the tightening nut 56 is loosened. Is also stable and easy, and it is possible to prevent the reactor piping seal device 50 from falling off as in the tightening operation.
[0060]
In this manner, the handling tool 59 can have an effect of not only detaching / removing the reactor piping seal device 50 from / to the reactor piping, but also stably fixing it. In order to exert such an effect, as shown in FIGS. 3 (a), 3 (b) and 5, a side plate 68 of the handling tool 59 is provided with a hole through which, for example, the socket portion 65 of the ratchet wrench 64 can pass. There is a need. Further, when the socket portion 65 is set on the side plate 68 as described above, it is possible to have a guide function for positioning.
[0061]
From the above, it is preferable that the reactor piping seal device 50 be attached and detached without a wrench, and the reactor piping seal device 50 is installed in the opening of the reactor piping after a wrench is installed, The tightening nut 56 is tightened or loosened. Thereby, the in-reactor pipe seal device 50 can be remotely attached and detached easily and reliably in a short time.
[0062]
Next, the first and second embodiments of the reactor piping sealing method according to the present invention will be described with reference to FIG. (Corresponding to claims 5 and 6)
FIG. 6 is a partial cross-sectional view showing a reactor pressure vessel and some internal reactor structures. FIG. 6 shows a state in which an operator 69 enters the core shroud 2 and performs an operation after the reactor piping seal device 50 is attached to the inside of the core spray piping 12 by the handling tool 59 and the water shielding is completed. It is shown.
[0063]
In FIG. 6, a new core shroud 2 is provided in a shroud support leg 4 via a shroud support cylinder 3 in a reactor pressure vessel 1, and an annulus portion formed by the reactor pressure vessel 1 and the core shroud 2 is provided. Is filled with water 48. Although not shown, an in-reactor pipe seal device 50 is installed at the opening of the core spray pipe 12 connected to the core spray purger 13 so that water 48 does not enter the core spray pipe 12. It has become. In the annulus, the jet pump 7 and the diffuser 38 are installed directly on the baffle plate 8. The worker 69 is working on the CRD housing 21.
[0064]
In order to be able to perform the work in this way, in the first embodiment of the present invention, first, for example, an annulus formed by the reactor pressure vessel 1 and the core shroud 2 can be accessed. It is necessary to carry out some of the reactor internal structures such as the steam dryer 15 and the upper grid plate 5 shown in FIG. Thereafter, the opening of the reactor internal pipe provided in the annulus is sealed to eliminate the possibility of water leaking through the internal reactor pipe such as the core spray pipe 12, and then the annulus up to the vicinity of the upper end of the core shroud 2. Water 48 is applied to the part to form a water shield. If water shielding can be formed in this way, radiation from the reactor pressure vessel 1 or the like can be shielded, and the work such as repair and replacement of the reactor internal structure can be performed safely and for a long time in the shroud. It becomes possible.
[0065]
Next, the second embodiment according to the present invention is particularly suitable when the core shroud 2 is replaced with a new one. When exchanging the core shroud, it is necessary to remove the core shroud 2 welded and fixed to the inner bottom of the reactor pressure vessel 1 after carrying out a part of the reactor internal structure out of the reactor pressure vessel 1. There is. Thereafter, a new core shroud 2 is carried into the reactor pressure vessel 1 and welded and fixed to the bottom of the reactor pressure vessel 1 again. Must be pre-welded in this way of This is to eliminate the gap between the new core shroud 2 and the bottom of the reactor pressure vessel 1 so that it does not leak when water is applied to the annulus. And the opening part of the core spray piping 12 provided in the annulus part comprised by the reactor pressure vessel 1 and the core shroud 2 will be sealed. Thereafter, water is applied to the annulus portion to form a water shield as in the first embodiment. However, even if the sealing of the opening is performed before welding the new core shroud 2 to the bottom of the reactor pressure vessel 1 and then water is applied to the vicinity of the upper end of the core shroud 2, the water shielding effect remains unchanged. .
[0066]
【The invention's effect】
According to the present invention, The stable reactor piping seal device can be handled by remote control, and the seal device can be prevented from falling. Also, If nuclear reactor internals and core shrouds can be replaced, inspected and repaired safely even for a long time, and if these replacement and inspection and repair operations can be performed safely even for a long time, a nuclear power plant Can be operated continuously over a long period of time.
[0067]
In particular, in the invention according to claim 2, the in-reactor pipe seal device can be prevented from entering the in-reactor pipe.
[0068]
In invention of Claim 3, 4, it can hold | grip by remote operation, without dropping a reactor piping seal apparatus. Therefore, the vicinity of the opening of the reactor internal pipe can be surely sealed by the seal member, and work safety and reliability can be improved.
[0069]
In particular, in the invention described in claim 4, the load is easily reduced with a smaller load than when the moving claw is driven by moving the movable shaft directly, for example, in the vertical direction. Can be engaged.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an in-reactor piping seal device according to first and second embodiments of the present invention as set forth in claims 1 and 2;
FIG. 2 is an enlarged cross-sectional view of an in-reactor piping seal device according to first and second embodiments of the present invention as set forth in claims 1 and 2;
FIG. 3 (a) is a front view of a handling tool of an in-reactor piping seal device according to a first embodiment of the invention described in claims 3 and 4, and FIG. 3 (b) is a side view thereof. is there.
4 (a) is a front view of a ratchet wrench for tightening or loosening a tightening nut of a reactor piping seal device, and FIG. 4 (b) is a side view thereof.
FIG. 5 is a longitudinal sectional view showing a state in which the socket portion of the ratchet wrench is set on the tightening nut while the handling tool is engaged with the reactor piping seal device.
6 shows a reactor pressure vessel and a part of the reactor internal structure for explaining the reactor piping sealing method according to the first and second embodiments of the invention described in claims 5 and 6; FIG. It is a fragmentary sectional view showing a thing.
FIG. 7 is a longitudinal sectional view showing the overall configuration of a reactor pressure vessel for explaining the prior art.
FIG. 8 is an enlarged cross-sectional view showing a part of the reactor pressure vessel for explaining the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel, 2 ... Core shroud, 3 ... Shroud support cylinder, 4 ... Shroud support leg, 5 ... Upper lattice plate, 6 ... Core support plate, 7 ... Jet pump, 7a ... Jet pump diffuser, 7b ... Jet Pump riser pipe, 7c ... Jet pump inlet mixer, 8 ... Baffle plate, 9 ... Control rod, 10 ... Fuel assembly, 11 ... Control rod guide pipe, 12 ... Core spray system piping, 13 ... Core spray purger, 14 ... Main Steam nozzle, 15 ... Steam dryer, 16 ... Steam / water shroud head, 17 ... Upper lid, 19 ... Space, 20 ... Control rod drive mechanism, 21 ... Control rod drive mechanism housing, 22 ... Water feed nozzle, 23 ... Cooling 24, core, 33 ... recirculation inlet nozzle, 34 ... transition piece, 35a, 35b ... elbow, 36a, 36 ... Mixing nozzle, 37a, 37b ... Inlet throat, 38, 38a, 38b ... Diffuser, 39 ... Measuring pipe, 40 ... Riser brace, 41 ... Ear part, 42 ... Groove part, 43 ... Jet pump beam, 44 ... Head bolt, 45 ... Riser blanket, 46 ... Baffle plate, 47 ... Support, 48 ... Water, 50 ... Reactor piping seal device, 51 ... Shield, 52 ... Seal member, 53 ... Fixed metal fitting, 54 ... Moving metal fitting, 55 ... Shaft 56 ... Clamping nut, 57 ... Collar portion, 58 ... Stopper, 59 ... Handling tool, 60 ... Fixed claw, 61 ... Moving claw, 62 ... Movable shaft, 62a ... Inner movable shaft, 62b ... Outer movable shaft, 63 ... Handle, 64 ... Ratchet wrench, 65 ... Socket part, 66 ... Pole, 67 ... Tightening bolt, 68 ... Side plate, 69 ... Worker

Claims (6)

In the reactor pipe sealing device installed at the opening of the reactor pipe provided in the annulus portion formed by the reactor pressure vessel and the core shroud welded and fixed to the bottom of the reactor pressure vessel, the reactor A fixed portion inserted into the opening of the pipe, a shaft provided in the fixed portion, a moving portion inserted through the shaft, a seal portion interposed between the moving portion and the fixed portion, and the shaft nut and, reactor piping seal device and having a flange portion you grip the handling member provided on the outer peripheral portion near the outside of the moving part to be screwed into. 2. The reactor piping seal device according to claim 1, further comprising a stopper having an outer diameter larger than the inner diameter of the opening that is integrated with the flange portion. Having a fixing claw to engage and move the pawl, and a movable shaft for the movement nail driven into engagement with the flange to the flange of the claims 1 to 2 reactor piping sealing device according Reactor piping seal device handling tool. The handling tool of the in-reactor piping seal device according to claim 3, wherein the movable shaft has a double cylindrical structure that is screwed through a thread groove, and the inner claw is rotated to drive the moving claw. Reactor piping seal device handling tool. A first procedure for carrying out a part of the structure provided in the reactor pressure vessel to the outside of the reactor pressure vessel, and a core shroud welded and fixed to the reactor pressure vessel and the bottom of the reactor pressure vessel A second procedure for sealing an opening of an in-reactor pipe provided in a configured annulus using the sealing device of claim 1 or 2 and the handling tool of claims 3 to 4, and the annulus. And a third procedure for filling the part with water. A first procedure for carrying out a part of the structure provided in the reactor pressure vessel to the outside of the reactor pressure vessel, and a second procedure for removing the core shroud fixedly welded to the inner bottom portion of the reactor pressure vessel And a third procedure for carrying a new core shroud into the reactor pressure vessel and welding and fixing it to the bottom of the reactor pressure vessel, and welding and fixing to the reactor pressure vessel and the bottom of the reactor pressure vessel A fourth procedure for sealing an opening of an in-reactor pipe provided in an annulus portion constituted by a core shroud using the sealing device according to claim 1 or 2 and the handling tool according to claims 3 to 4 ; And a fifth procedure for filling the annulus portion with water.

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