A method of repairing a spent fuel transport container drain

Abstract

The application discloses a kind of spent fuel transport container drain pipe's maintenance method, comprising the following steps: removing screw plug ring, using limiting sleeve removes screw plug ring on drain pipe;Remove drain pipe, insert expansion plug into the pipe opening of drain pipe, using lifting equipment to pull out drain pipe;Get new drain pipe, according to the height of spent fuel transport container, the size of new drain pipe and the installation position of copper hoop are obtained, and new drain pipe is cut from drain pipe raw material;Install copper hoop, using copper hoop pre-tightening piece to install copper hoop to the corresponding installation position of new drain pipe;Install new drain pipe, insert expansion plug into the pipe opening of new drain pipe, using lifting equipment to insert new drain pipe into water collecting tank;Install screw plug ring, using limiting sleeve installs screw plug ring at the pipe opening of new drain pipe.The spent fuel transport container drain pipe's maintenance method provided by the application improves the maintenance convenience of spent fuel transport container drain pipe, reduces the risk of drain pipe maintenance.

Description

A method for repairing the drain pipe of a spent fuel transport container Technical Field

[0001] This invention relates to the field of spent fuel transport container technology, and more specifically, to a method for repairing the drain pipe of a spent fuel transport container. Background Technology

[0002] The NAC-STC container is a spent fuel transport container. After spent fuel is loaded using the wet method, the boron-containing water inside the container needs to be drained through a drain pipe via an air-filling and drainage method. As shown in Figures 3 and 4, a water collection tank is located at the bottom of the NAC-STC container's inner cavity. The bottom end of the drain pipe extends into the water collection tank. Because the bottom end of the drain pipe is flat, it fits well against the bottom of the water collection tank after being lowered, hindering the flow of the medium and severely affecting the filling and draining of the container. Therefore, there is a certain distance between the bottom end of the drain pipe and the bottom of the water collection tank. During the manufacturing process of the NAC-STC container, the drain pipe is installed when the NAC-STC container is in a horizontal position and the fuel basket is not installed inside the cavity. After the NAC-STC container has been loaded with spent fuel, the radiation dose level inside the NAC-STC container is high. If the fuel basket is removed before maintenance of the drain pipe, there is a significant safety risk, making drain pipe maintenance difficult.

[0003] Therefore, how to improve the ease of maintenance of the drain pipes of spent fuel transport containers and reduce the risks of drain pipe maintenance has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a maintenance method for the drain pipe of a spent fuel transport container, so as to improve the ease of maintenance of the drain pipe and reduce the risk of drain pipe maintenance.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for repairing the drain pipe of a spent fuel transport container, comprising the following steps:

[0007] Remove the screw plug ring by using a limiting sleeve to remove the screw plug ring on the drain pipe, so that the pipe opening of the drain pipe is exposed;

[0008] Remove the drain pipe, insert an expansion plug into the opening of the drain pipe, and use a lifting device to pull the expansion plug and the drain pipe out of the water collection tank of the spent fuel transport container.

[0009] Obtain a new drainage pipe, calculate the size of the new drainage pipe and the installation position of the copper hoop based on the height of the spent fuel transport container, and cut the new drainage pipe from the drainage pipe raw material;

[0010] Install copper hoops by using copper hoop pretensioners to install the copper hoops to the corresponding installation position of the new drainage pipe;

[0011] Install a new drain pipe, insert the expansion plug into the opening of the new drain pipe, and use a lifting device to pull the expansion plug and the new drain pipe into the water collection tank of the spent fuel transport container;

[0012] Install the screw plug ring, and use the limiting sleeve to install the screw plug ring at the opening of the new drain pipe.

[0013] Optionally, in the above-described method for repairing the drain pipe of a spent fuel transport container, obtaining a new drain pipe includes the following steps:

[0014] Obtain the target length of the new drainage pipe according to the calculation formula L. t-min =A+L fnf L t-max =B+L fnf and L fnf =L f +L nf Calculate the minimum and maximum target lengths, obtain the target length of the new drainage pipe based on the minimum and maximum target lengths, and mark it, where L f L is the length of the copper hoop. nf Let A and B be the distance from the edge of the copper hoop to the end face of the copper hoop pretensioner after the copper hoop is placed inside the copper hoop pretensioner. Both A and B are constants.

[0015] Obtain the new drain pipe length, cut the drain pipe raw material according to the markings, and measure the length L of the new drain pipe after cutting. t1 ;

[0016] To determine the installation location of the copper hoop, use formula L. Edt =L t1 -(C+L fnf The length L of the new drainage pipe extending beyond the end face of the copper hoop pretensioner is calculated. Edt According to L Edt The installation position of the copper hoop is obtained.

[0017] Optionally, in the above-mentioned maintenance method for the drain pipe of the spent fuel transport container, the copper hoop pre-tightening component includes a fixed base and a pre-tightening head. The fixed base has a stepped through hole at its center for the drain pipe to pass through, and the copper hoop is located in the stepped through hole. The pre-tightening head has a round hole at its center for the drain pipe to pass through, and the outer wall of the pre-tightening head has a stepped portion that mates with the stepped through hole, for applying a pre-tightening force to the copper hoop fitted on the outside of the drain pipe.

[0018] Optionally, in the above-mentioned maintenance method for the drain pipe of the spent fuel transport container, the stepped through hole is provided with an internal thread, the pre-tightening head is provided with an external thread, the pre-tightening head is threadedly engaged with the fixed base, and the end of the pre-tightening head is provided with a screwing part for easy screwing of the pre-tightening head.

[0019] Optionally, in the above-described method for repairing the drain pipe of a spent fuel transport container, the cross-section of the screw-in part is hexagonal; and / or,

[0020] The fixed base is a hexagonal prism.

[0021] Optionally, in the above-mentioned maintenance method for the drain pipe of the spent fuel transport container, the insertion end of the pre-tightening head is provided with a first chamfered portion that mates with the first side edge of the copper hoop, and the stepped through hole is provided with a second chamfered portion that mates with the second side edge of the copper hoop, wherein the inclination angles of the first chamfered portion and the second chamfered portion are equal.

[0022] Optionally, in the above-mentioned maintenance method for the drain pipe of the spent fuel transport container, the limiting sleeve includes a round rod for gripping and a frustum disposed at the first end of the round rod. A boss is provided on the frustum, the outer diameter of which is smaller than the inner diameter of the screw plug ring. A limiting part is provided on the boss, and a limiting groove is provided on the screw plug ring. The limiting part on the boss cooperates with the limiting groove on the screw plug ring so that the limiting sleeve rotates synchronously with the screw plug ring. The second end of the round rod is provided with a connecting part for connecting to a ratchet wrench.

[0023] Optionally, in the above-mentioned maintenance method for the drain pipe of the spent fuel transport container, the limiting part includes wing plates symmetrically arranged on both sides of the boss, and the wing plates engage with the limiting groove of the screw plug ring.

[0024] Optionally, in the above-described maintenance method for the drain pipe of the spent fuel transport container, the expansion plug includes an expansion kit and a screw for driving and compressing the expansion kit. The expansion kit includes a compression sleeve and a rubber sleeve connected to the end of the compression sleeve. The screw is provided with a rotation knob for rotating the screw so that the screw drives the compression sleeve to compress the rubber sleeve.

[0025] Optionally, in the above-mentioned maintenance method for the drain pipe of the spent fuel transport container, the rotating knob is a wing nut, and the end of the lead screw is provided with an extension that cooperates with the rotating knob.

[0026] The present invention provides a method for repairing the drain pipe of a spent fuel transport container, comprising the steps of removing the screw plug ring, removing the drain pipe, obtaining a new drain pipe, installing a copper clamp, installing the new drain pipe, and installing the screw plug ring. In the process of removing the screw plug ring, a limiting sleeve is used to remove the screw plug ring from the drain pipe to expose the drain pipe opening. In the drain pipe removal step, an expansion plug is inserted into the drain pipe opening, and a lifting device is used to pull the expansion plug along with the drain pipe from the water collection tank of the spent fuel transport container. In the new drain pipe acquisition step, the dimensions of the new drain pipe and the installation position of the copper clamp are calculated based on the height of the spent fuel transport container, and the new drain pipe is cut from the drain pipe raw material. In the copper clamp installation step, a copper clamp pre-tightening component is used to install the copper clamp at the corresponding installation position on the new drain pipe, ensuring that the copper clamp engages with the support base of the spent fuel transport container to prevent the new drain pipe from falling to the bottom of the water collection tank during installation. In the new drain pipe installation step, an expansion plug is inserted into the opening of the new drain pipe, and a lifting device is used to pull the expansion plug and the new drain pipe into the water collection tank of the spent fuel transport container to complete the installation of the new drain pipe. In the screw plug ring installation step, a limiting sleeve is used to install the screw plug ring at the opening of the new drain pipe, thus completing the drain pipe repair and replacement work.

[0027] Compared with the prior art, the maintenance method for the drain pipe of the spent fuel transport container provided by the present invention completes the maintenance work of the drain pipe through six steps: removing the screw plug ring, removing the drain pipe, obtaining a new drain pipe, installing the copper hoop, installing the new drain pipe, and installing the screw plug ring. The method uses a limiting sleeve, an expansion plug, and a copper hoop pre-tightening component to disassemble and assemble the drain pipe and the screw plug ring and copper hoop set on the drain pipe, thereby improving the convenience of maintenance of the drain pipe of the spent fuel transport container and reducing the risk of drain pipe maintenance. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figure 1 is a flowchart of a method for repairing the drain pipe of a spent fuel transport container provided in an embodiment of the present invention;

[0030] Figure 2 is a flowchart of obtaining a new drainage pipe according to an embodiment of the present invention;

[0031] Figure 3 is a schematic diagram of the structure of the spent fuel transport container provided in an embodiment of the present invention;

[0032] Figure 4 is a partial enlarged view of point A in Figure 3 provided in an embodiment of the present invention;

[0033] Figure 5 is a partial enlarged view of point B in Figure 3 provided in an embodiment of the present invention;

[0034] Figure 6 is a top view of the screw plug ring provided in an embodiment of the present invention;

[0035] Figure 7 is a cross-sectional view of AA in Figure 6 provided in an embodiment of the present invention;

[0036] Figure 8 is a schematic diagram of the structure of the limiting sleeve provided in an embodiment of the present invention;

[0037] Figure 9 is a cross-sectional view of BB in Figure 8 provided in an embodiment of the present invention;

[0038] Figure 10 is a schematic diagram of the expansion plug provided in an embodiment of the present invention;

[0039] Figure 11 is a schematic diagram of the structure of the copper hoop pretensioner provided in an embodiment of the present invention.

[0040] Among them, 100 is the limiting sleeve, 101 is the limiting part, 102 is the round rod, 103 is the frustum, 104 is the boss, and 105 is the connecting part;

[0041] 200 is the expansion plug, 201 is the lead screw, 202 is the compression sleeve, 203 is the rubber sleeve, 204 is the rotary knob, 205 is the extension, and 206 is the limit nut.

[0042] 300 is the copper hoop pre-tightening part, 301 is the fixed base, 3011 is the stepped through hole, 3012 is the second chamfer part, 302 is the pre-tightening head, 3021 is the stepped part, 3022 is the screwing part, and 3023 is the first chamfer part.

[0043] 400 is a spent fuel transport container, 401 is a drain pipe, 4011 is a copper hoop, 4012 is the first side edge, 4013 is the second side edge, 402 is a water collection tank, 403 is a support base, 4031 is the third chamfer, 404 is a screw plug ring, 4041 is a limiting groove, and 4042 is the fourth chamfer. Detailed Implementation

[0044] The core of this invention is to provide a maintenance method for the drain pipe of a spent fuel transport container, so as to improve the ease of maintenance of the drain pipe and reduce the risk of drain pipe maintenance.

[0045] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0046] As shown in Figure 1, this embodiment of the invention discloses a method for repairing the drain pipe of a spent fuel transport container. It should be noted that, as shown in Figures 3 and 4, a water collection trough 402 is located at the bottom of the inner cavity of the NAC-STC container. The bottom end of the drain pipe 401 extends into the water collection trough 402. Because the bottom end of the drain pipe 401 is flat, it fits well with the bottom of the water collection trough 402 after being lowered, which will hinder the flow of the medium and seriously affect the filling and draining of the container. Therefore, there is a certain distance between the bottom end of the drain pipe 401 and the bottom of the water collection trough 402. During the manufacturing process of the NAC-STC container, the drain pipe 401 is installed when the NAC-STC container is in a horizontal state and the inner cavity is not equipped with a fuel basket. After the NAC-STC container has been loaded with spent fuel, the radiation dose level inside the NAC-STC container is high. If the fuel basket is lifted out before repairing the drain pipe 401, there is a significant safety risk, making the repair of the drain pipe 401 quite difficult. This invention discloses a repair method for the drain pipe of a spent fuel transport container. The repair of drain pipe 401 is completed in six steps: removing the screw plug ring, removing the drain pipe, obtaining a new drain pipe, installing a copper clamp, installing the new drain pipe, and installing the screw plug ring again. A limiting sleeve 100, an expansion plug 200, and a copper clamp pre-tightening component 300 are used to disassemble and assemble drain pipe 401, the screw plug ring 404, and the copper clamp 4011 mounted on drain pipe 401. This improves the ease of repairing the drain pipe of the spent fuel transport container and reduces the risk of repairing drain pipe 401. The repair method for the drain pipe of the spent fuel transport container includes:

[0047] Step S100: Remove the screw plug ring;

[0048] The screw plug ring 404 on the drain pipe 401 is removed using a limiting sleeve 100 to expose the opening of the drain pipe 401. Specifically, the limiting sleeve 100 is provided with a limiting part 101, and the screw plug ring 404 is provided with a limiting groove 4041. By cooperating between the limiting part 101 of the limiting sleeve 100 and the limiting groove 4041 of the screw plug ring 404, the screw plug ring 404 and the limiting sleeve 100 rotate synchronously, thereby achieving the purpose of removing the screw plug ring 404 by rotating the limiting sleeve 100.

[0049] As shown in Figures 6 to 9, in one specific embodiment, as shown in Figures 6 and 7, the limiting sleeve 100 includes a round rod 102 for easy gripping and a frustum 103 disposed at the first end of the round rod 102. A boss 104 is provided on the frustum 103. The outer diameter of the boss 104 is smaller than the inner diameter of the screw plug ring 404 so that the boss 104 can be inserted into the screw plug ring 404. At the same time, a limiting part 101 is disposed on the boss 104. The limiting part 101 includes wing plates symmetrically disposed on both sides of the boss 104. When the boss 104 is inserted into the screw plug ring 404, the wing plates engage with the limiting groove 4041 of the screw plug ring 404 to ensure that the screw plug ring 404 and the limiting sleeve 100 rotate synchronously, as shown in Figures 6 and 7. Furthermore, a connecting part 105 for connecting to a ratchet wrench is provided at the second end of the round rod 102. The connecting part 105 can be a hexagonal prism that mates with the ratchet wrench, or it can be an internal hexagonal prism that mates with an internal hexagonal wrench, thereby achieving the purpose of removing the screw plug ring 404 by rotating the limiting sleeve 100. In addition, in order to improve the service life of the limiting sleeve 100, the limiting sleeve 100 is made of high-strength stainless steel, such as 304 stainless steel.

[0050] S101, Remove the drain pipe;

[0051] The expansion plug 200 is inserted into the opening of the drain pipe 401, and a lifting device is used to pull the expansion plug 200 and the drain pipe 401 out of the water collection tank 402 of the spent fuel transport container 400. Specifically, after the screw plug ring 404 is removed, the expansion plug 200 is inserted into the opening of the drain pipe 401, so that the expansion plug 200 abuts against the inner wall of the opening of the drain pipe 401 in the expanded state, thereby preventing the drain pipe 401 from detaching from the expansion plug 200 when it is pulled out. The expansion plug 200 is then used to pull the drain pipe 401 out of the water collection tank 402 of the spent fuel transport container 400, thereby removing the drain pipe 401.

[0052] As shown in Figure 10, in one specific embodiment, the expansion plug 200 includes an expansion kit and a lead screw 201 for driving the compression of the expansion kit. The expansion kit includes a compression sleeve 202 and a rubber sleeve 203 connected to the end of the compression sleeve 202. The lead screw 201 is provided with a rotating knob 204 for rotating the lead screw 201 so that the lead screw 201 drives the compression sleeve 202 to compress the rubber sleeve 203. The rotating knob 204 is a wing nut, which makes it easy for the operator to apply a torque to make the rotating knob 204 rotate. The end of the lead screw 201 is provided with an extension 205 that cooperates with the rotating knob 204. Specifically, the lead screw 201 passes sequentially through the extrusion sleeve 202 and the rubber sleeve 203 connected to the end of the extrusion sleeve 202, and extends out of the rubber sleeve 203. A limiting nut 206 engages with the protruding end of the lead screw 201 to limit the rubber sleeve 203, preventing it from falling off. Tightening the rotating knob 204 moves the lead screw 201 upwards (view from Figure 10), while simultaneously moving the extrusion sleeve 202 downwards relative to the lead screw 201 (Figure 10). (From a certain perspective), under the combined action of the compression sleeve 202 and the limiting nut 206, the rubber sleeve 203 is compressed at both ends and expands, and abuts against the inner wall of the drain pipe 401 until the drain pipe 401 can be freely lifted through the expansion plug 200. At this time, the lifting equipment is connected to the extension 205 of the screw rod 201 by using flexible traction components such as ropes, so as to pull out the drain pipe 401 through the expansion plug 200, thereby completing the disassembly process of the drain pipe 401.

[0053] S102, Obtain a new drain pipe;

[0054] The dimensions of the new drain pipe and the installation position of the copper clamp 4011 are calculated based on the height of the spent fuel transport container 400, and the new drain pipe is cut from the drain pipe raw material. Specifically, as shown in Figure 2, it includes:

[0055] S1021, Obtain the target length of the new drainage pipe;

[0056] According to the calculation formula L t-min =A+L fnf L t-max =B+L fnf and L fnf =L f +L nf Calculate the minimum and maximum target lengths, obtain the target length of the new drainage pipe based on these values, and mark it. The target length of the new drainage pipe can be the minimum and maximum target lengths, or it can be the average value, depending on the actual needs of the spent fuel transport container 400. Where L... f L is the length of the copper hoop. nfThe distance from the second side edge 4013 of the copper hoop to the end face of the copper hoop pretensioner after the copper hoop is placed inside the copper hoop pretensioner is constant, as shown in Figure 11. In this embodiment, A is 4164 mm, B is 4170 mm, and the target length of the new drain pipe is not less than 4180 mm. The values ​​of A and B are obtained by summing the value of C with the minimum and maximum values ​​of the allowable insertion of the drain pipe 401 into the screw plug ring 404. The value of C is the distance from the first side edge 4012 of the copper hoop to the bottom end of the drain pipe 401. In this embodiment, the value of C is 4147 mm. It should be noted that the minimum and maximum values ​​of the allowable insertion of the screw plug ring 404 are determined according to the actual situation of the spent fuel transport container 400, and the allowable error of the target length of the new drain pipe is ±1 mm.

[0057] S1022, Obtain the new drain pipe length;

[0058] Cut the raw drainage pipe material according to the markings, and measure the length L of the new drainage pipe after cutting. t1 .

[0059] S1023, Obtain the installation position of the copper hoop;

[0060] According to formula L Edt =L t1 -(C+L fnf The length L of the new drainage pipe extending 300 mm beyond the end face of the copper clamp pretensioner was calculated. Edt According to L Edt The installation position of the copper hoop is obtained, as shown in Figure 11. Here, C is the distance from the first edge 4012 of the copper hoop to the bottom of the drain pipe 401; in this embodiment, C is taken as 4147 mm. It should be noted that L... Edt The allowable error is ±1mm.

[0061] S103, Install copper hoops;

[0062] Copper hoop 4011 is installed at the corresponding installation position of the new drain pipe using copper hoop pretensioner 300, so that copper hoop 4011 cooperates with the support base 403 of spent fuel transport container 400, preventing drain pipe 401 from falling to the bottom of water collection tank 402 of spent fuel transport container 400, obstructing the flow of medium, and seriously affecting the filling and draining of container.

[0063] As shown in Figure 11, in one specific embodiment, the copper hoop pre-tightening component 300 includes a fixed base 301 and a pre-tightening head 302. The fixed base 301 has a stepped through-hole 3011 at its center for the drain pipe 401 to pass through. The copper hoop 4011 is located within the stepped through-hole 3011. The pre-tightening head 302 has a circular hole at its center for the drain pipe 401 to pass through. The outer wall of the pre-tightening head 302 has a stepped portion 3021 that mates with the stepped through-hole 3011, used to apply pre-tightening force to the copper hoop 4011 fitted onto the outside of the drain pipe 401. Specifically, the stepped through-hole 3011 has an internal thread, and the pre-tightening head 302 has an external thread. The pre-tightening head 302 is threadedly engaged with the fixed base 301. The end of the pre-tightening head 302 has a screwing portion 3022 for easy screwing. Meanwhile, the pre-tightening head 302 has a first chamfered portion 3023 at its insertion end that mates with the first side edge 4012 of the copper hoop 4011, and a second chamfered portion 3012 that mates with the second side edge 4013 of the copper hoop 4011 is provided inside the stepped through hole 3011. The inclination angles of the first chamfered portion 3023 and the second chamfered portion 3012 are equal. The screwing part 3022 has a hexagonal cross-section, and / or the fixing base 301 has a hexagonal prism shape, which facilitates the application of torque to the pre-tightening head 302 using a torque wrench. By rotating the pre-tightening head 302, the first chamfered portion 3023 of the pre-tightening head 302 is brought into contact with the first side edge 4012 of the copper hoop 4011. Continuing to rotate the pre-tightening head 302 causes the copper hoop 4011 to press against the drain pipe 401 under the squeezing action of the first chamfered portion 3023 of the pre-tightening head 302 and the second chamfered portion 3012 within the stepped through hole 3011, thus completing the installation of the copper hoop 4011 and the drain pipe 401. Furthermore, to improve the service life of the copper hoop pre-tightening component 300, it is made of high-strength stainless steel, such as 304 stainless steel.

[0064] S104, Install a new drain pipe;

[0065] The expansion plug 200 is inserted into the opening of the new drain pipe, and a lifting device is used to lift the expansion plug 200 and the new drain pipe into the water collection tank 402 of the spent fuel transport container 400. Specifically, the expansion plug 200 is inserted into the opening of the new drain pipe 401, and a lifting device is used to lift the expansion plug 200 and the drain pipe 401 into the water collection tank 402 of the spent fuel transport container 400. The copper hoop 4011 is fitted with the third chamfer 4031 of the support base 403 of the spent fuel transport container 400, as shown in Figure 5. It should be noted that in this embodiment, the method of using the expansion plug 200 is similar to the method of using the expansion plug 200 in the step of removing the drain pipe in S101, and will not be described again here.

[0066] S105, Install the screw plug ring;

[0067] The screw plug ring 404 is installed at the opening of the new drain pipe using a limiting sleeve 100. Specifically, the screw plug ring 404 is installed at the opening of the drain pipe 401 using the limiting sleeve 100, and the fourth chamfered portion 4042 of the screw plug ring 404 is fitted with the copper clamp 4011, as shown in Figure 5. A ratchet wrench and a torque wrench are used to apply a rotational torque to the screw plug ring 404, so that the copper clamp 4011, under the combined action of the third chamfered portion 4031 of the support base 403 and the fourth chamfered portion 4042 of the screw plug ring 404, further presses the drain pipe 401, thereby preventing the drain pipe 401 from falling off, as shown in Figure 5. In this embodiment, the outer wall of the screw plug ring 404 is provided with external threads, and the support seat 403 of the spent fuel transport container 400 is provided with internal threads. First, a ratchet wrench and a limiting sleeve 100 are used to install the screw plug ring 404 onto the support seat 403 of the spent fuel transport container 400 through the threaded engagement of the screw plug ring 404 and the support seat 403 of the spent fuel transport container 400. Then, a torque of 14 N·m is applied by a torque wrench so that the fourth chamfered portion 4042 of the screw plug ring 404 fits against the edge of the copper hoop 4011. Thus, under the combined action of the third chamfered portion 4031 of the support seat 403 and the fourth chamfered portion 4042 of the screw plug ring 404, the copper hoop 4011 further presses the drain pipe 401 to prevent the drain pipe 401 from falling off, thereby fixing the drain pipe 401.

[0068] The present invention discloses a maintenance method for a drain pipe of a spent fuel transport container, comprising the steps of removing a screw plug ring, removing the drain pipe, obtaining a new drain pipe, installing a copper clamp, installing the new drain pipe, and installing a screw plug ring. Specifically, in the step of removing the screw plug ring, a limiting sleeve 100 is used to remove the screw plug ring 404 on the drain pipe 401, exposing the opening of the drain pipe 401; in the step of removing the drain pipe, an expansion plug 200 is inserted into the opening of the drain pipe 401, and a lifting device is used to pull the expansion plug 200 along with the drain pipe 401 from the water collection tank 402 of the spent fuel transport container 400; in the step of obtaining a new drain pipe, the dimensions of the new drain pipe and the installation position of the copper clamp 4011 are calculated based on the height of the spent fuel transport container 400, and the new drain pipe is cut from the drain pipe raw material; in the step of installing the copper clamp, a copper clamp pre-tightening member 300 is used to tighten the copper clamp. The clamp 4011 is installed at the corresponding installation position of the new drain pipe so that the copper clamp 4011 cooperates with the support base 403 of the spent fuel transport container 400 to prevent the new drain pipe from falling to the bottom of the water collection tank 402 during installation. In the step of installing the new drain pipe, the expansion plug 200 is inserted into the pipe opening of the new drain pipe, and the expansion plug 200 together with the new drain pipe is inserted into the water collection tank 402 of the spent fuel transport container 400 using lifting equipment to complete the installation of the new drain pipe. In the step of installing the screw plug ring, the screw plug ring 404 is installed at the pipe opening of the new drain pipe through the limiting sleeve 100, thereby completing the maintenance and replacement work of the drain pipe 401.

[0069] Compared with the prior art, the maintenance method for the drain pipe of the spent fuel transport container disclosed in this invention completes the maintenance of the drain pipe 401 in six steps: removing the screw plug ring, removing the drain pipe, obtaining a new drain pipe, installing the copper hoop, installing the new drain pipe, and installing the screw plug ring. The drain pipe 401 and the screw plug ring 404 and copper hoop 4011 set on the drain pipe 401 are disassembled and assembled using the limiting sleeve 100, the expansion plug 200, and the copper hoop pre-tightening component 300, thereby improving the convenience of maintenance of the drain pipe of the spent fuel transport container and reducing the risk of maintenance of the drain pipe 401.

[0070] The terms "first" and "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units may include steps or units not listed, but rather steps or units not listed.

[0071] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for repairing the drain pipe of a spent fuel transport container, characterized in that, The steps include: removing the screw plug ring, using a limiting sleeve (100) to remove the screw plug ring (404) on the drain pipe (401) to expose the opening of the drain pipe (401); removing the drain pipe, inserting an expansion plug (200) into the opening of the drain pipe (401), and using a lifting device to pull the expansion plug (200) and the drain pipe (401) out of the water collection tank (402) of the spent fuel transport container (400); obtaining a new drain pipe, calculating the size of the new drain pipe and the installation of the copper clamp (4011) based on the height of the spent fuel transport container (400). The location is determined, and the new drainage pipe is cut from the raw material of the drainage pipe; copper hoop is installed, and the copper hoop (4011) is installed at the corresponding installation position of the new drainage pipe using copper hoop pretensioner (300); the new drainage pipe is installed, and the expansion plug (200) is inserted into the opening of the new drainage pipe, and the expansion plug (200) is used to drive the new drainage pipe into the water collection tank (402) of the spent fuel transport container (400) using lifting equipment; the screw plug ring is installed, and the screw plug ring (404) is installed at the opening of the new drainage pipe using the limiting sleeve (100).

2. The method for repairing the drain pipe of a spent fuel transport container according to claim 1, characterized in that, The process of obtaining the new drainage pipe includes the following steps: obtaining the target length of the new drainage pipe, based on the calculation formula L. t-min = A + L fnf L t-max = B + L fnf and L fnf =L f + L nf Calculate the minimum and maximum target lengths, obtain the target length of the new drainage pipe based on the minimum and maximum target lengths, and mark it, where L f L is the length of the copper hoop. nf Let A and B be the distance from the edge of the copper hoop to the end face of the copper hoop pretensioner after the copper hoop is placed inside the copper hoop pretensioner; both A and B are constants. Obtain the new drain pipe length, cut the drain pipe raw material according to the markings, and measure the length L of the new drain pipe after cutting. t1 ; To determine the installation location of the copper hoop, use formula L. Edt =L t1 - (C + L) fnf The length L of the new drainage pipe extending beyond the end face of the copper hoop pretensioner (300) is calculated. Edt According to L Edt The installation position of the copper hoop is obtained, and the value of C is the distance from the first side edge (4012) of the copper hoop to the bottom end of the drain pipe (401).

3. The method for repairing the drain pipe of a spent fuel transport container according to claim 1, characterized in that, The copper hoop pretensioner (300) includes a fixed base (301) and a pretensioner head (302). The fixed base (301) has a stepped through hole (3011) at its center for the drain pipe (401) to pass through. The copper hoop (4011) is located inside the stepped through hole (3011). The pretensioner head (302) has a round hole at its center for the drain pipe (401) to pass through. The outer wall of the pretensioner head (302) has a stepped portion (3021) that mates with the stepped through hole (3011) for applying pretension force to the copper hoop (4011) fitted on the outside of the drain pipe (401).

4. The method for repairing the drain pipe of a spent fuel transport container according to claim 3, characterized in that, The stepped through hole (3011) is provided with an internal thread, the preload head (302) is provided with an external thread, the preload head (302) is threadedly engaged with the fixed base (301), and the end of the preload head (302) is provided with a screwing part (3022) for easy screwing of the preload head (302).

5. The method for repairing the drain pipe of a spent fuel transport container according to claim 4, characterized in that, The cross-section of the screwing part (3022) is hexagonal; and / or the fixing base (301) is a hexagonal prism.

6. The method for repairing the drain pipe of a spent fuel transport container according to claim 4, characterized in that, The pre-tightening head (302) has a first chamfered portion (3023) that mates with the first side edge (4012) of the copper hoop (4011) at its insertion end. The stepped through hole (3011) has a second chamfered portion (3012) that mates with the second side edge (4013) of the copper hoop (4011). The first chamfered portion (3023) and the second chamfered portion (3012) have the same inclination angle.

7. The method for repairing the drain pipe of a spent fuel transport container according to claim 1, characterized in that, The limiting sleeve (100) includes a round rod (102) for gripping and a frustum (103) disposed at the first end of the round rod (102). A boss (104) is provided on the frustum (103). The outer diameter of the boss (104) is smaller than the inner diameter of the screw plug ring (404). A limiting part (101) is provided on the boss (104). A limiting groove (4041) is provided on the screw plug ring (404). The limiting part (101) on the boss (104) cooperates with the limiting groove (4041) on the screw plug ring (404) so ​​that the limiting sleeve (100) and the screw plug ring (404) rotate synchronously. A connecting part (105) for connecting with a ratchet wrench is provided at the second end of the round rod (102).

8. The method for repairing the drain pipe of a spent fuel transport container according to claim 7, characterized in that, The limiting part (101) includes wing plates symmetrically arranged on both sides of the boss (104), and the wing plates engage with the limiting groove (4041) of the screw plug ring (404).

9. The method for repairing the drain pipe of a spent fuel transport container according to claim 1, characterized in that, The expansion plug (200) includes an expansion kit and a screw (201) for driving and compressing the expansion kit. The expansion kit includes a compression sleeve (202) and a rubber sleeve (203) connected to the end of the compression sleeve (202). The screw (201) is provided with a rotation knob (204) for rotating the screw (201) so that the screw (201) drives the compression sleeve (202) to compress the rubber sleeve (203).

10. The method for repairing the drain pipe of a spent fuel transport container according to claim 9, characterized in that, The rotary knob (204) is a wing nut, and the end of the lead screw (201) is provided with an extension (205) that cooperates with the rotary knob (204).

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