A device and method for mitigating remote expansion of a padlock lug cap for a thermal insulating sleeve

Abstract

The present application belongs to the technical field of nuclear power, and particularly relates to a device and method for relieving the remote expansion of a locking cap of a heat insulation sleeve. The device comprises a locking cap expansion device and a long rod. The long rod is used for remote operation above a water pool. The locking cap expansion device comprises a positioning pin, a positioning cylinder, a clamping claw, an alignment screwing operation head, an expansion head and a pressing expansion operation head. The present application has the beneficial effect that the remote operation of the locking of the locking cap of the relief pad is realized by using the long rod to remotely operate the screwing, positioning, alignment and pressing expansion. The special device integrating the positioning of the expansion tool, the screwing positioning of the expansion head, the clamping and fixing and the pressing expansion is used to realize the integrated operation of the underwater remote expansion of the locking cap of the relief pad, and the process steps are simplified.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power technology, specifically relating to a device and method for remotely tightening the locking cap of the gasket in a heat insulation sleeve. Background Technology

[0002] The insulation sleeve is a component of the control rod drive mechanism, suspended in the CRDM pipe seat on the pressure vessel top cover. The installation method is radial clearance fit with no axial constraint. During unit operation, the insulation sleeve is affected by vibrations induced by the primary circuit medium flow, causing rubbing at the joint between its upper end and the CRDM pipe seat flange, resulting in a drop in the insulation sleeve's height. With prolonged operation, wear at the insulation sleeve end exacerbates the drop in its position. Without intervention, the settlement distance of the insulation sleeve will increase, eventually leading to the entire insulation sleeve falling after the end is completely worn away.

[0003] Currently, in the nuclear power industry, a common mitigation solution is to install mitigation pads on the upper cover plate of the control rod guide tube in the upper reactor internals. The pad consists of a cone and a flange. The flange has three sets of evenly distributed bolts and locking caps, and two evenly distributed positioning holes below the flange. The pad is positioned by the positioning holes engaging with anti-rotation pins on the upper cover plate of the guide tube. The pad is secured by the three sets of bolts, and loosening is prevented by the locking caps that engage with the bolts.

[0004] Since the contact dose of the guide tube is approximately 15 mSv / h, it requires shielding with boric acid solution. Therefore, the installation of the pad on the upper surface of the guide tube must be carried out underwater. The guide tube is immersed in boric acid solution (boric acid concentration 2400-2500 ppm), and the operator performs remote operation from an auxiliary bridge above the pool. The entire installation process includes positioning the tightening tool, tightening the tightening head, clamping and fixing, and applying downward pressure for tightening. Summary of the Invention

[0005] The purpose of this invention is to provide a device and method for remotely tightening the pad locking cap of a heat insulation sleeve, which can integrate the positioning of the tightening tool, the screwing and positioning of the tightening head, the clamping and fixing, and the downward tightening, and is used to relieve the underwater remote tightening of the pad locking cap.

[0006] The technical solution of the present invention is as follows: a device for remotely tightening the locking cap of the heat insulation sleeve, comprising a locking cap tightening device and a long rod, wherein the long rod is used for remote operation above the water tank, and the locking cap tightening device comprises a positioning pin, a positioning cylinder, a clamping claw, an alignment and screwing operation head, a tightening head and a downward tightening operation head.

[0007] The positioning pin is cylindrical with a tapered guide. It is inserted into the installation process hole on the gasket flange and cooperates with the positioning cylinder to realize the positioning of the locking cap tightening device on the gasket.

[0008] The positioning cylinder is located at the center of the locking cap tensioning device, and is inserted into the center hole of the guide cylinder cover plate through the center hole of the pad to play a centering role.

[0009] The clamping claws consist of three parts, which are evenly mounted on the positioning cylinder via pins and can rotate around the pins to fix them to the pad.

[0010] The clamping and releasing of the gripper is achieved through the gripper drive rod and the gripper cylinder. When the lower part of the gripper cylinder is supplied with air, the gripper drive rod moves upward and drives the gripper to retract and release through contact with the wedge-shaped surface of the gripper. When the upper part of the gripper cylinder is supplied with air, the gripper drive rod moves downward and drives the gripper to be opened through contact with the wedge-shaped surface of the gripper, thereby achieving clamping and fixing with the inner conical surface of the pad block.

[0011] The upper end of the alignment and tightening operating head has a tapered outer square structure, which cooperates with the inner square of the long rod to achieve the function of rotating the tightening head.

[0012] The tightening head includes a positioning hexagonal head and a notched post. The positioning hexagonal head expands and contracts under the action of the upper spring force. The positioning hexagonal head engages with the inner hexagonal part of the bolt. The notched post is positioned relative to the bolt notch by the positional relationship of the components of the tightening head.

[0013] The aforementioned pressure tightening operating head is a rotating component driven to rotate by a long rod. Its lower end is a threaded pair, which drives the pressure plate to move up and down through the rotation of the screw. When moving downward, it presses down on the rotating tightening head, and the notched column presses down to drive the locking cap to deform towards the notch of the bolt, thereby achieving locking.

[0014] A method for remotely tightening the locking cap of a gasket in an insulation sleeve includes the following steps:

[0015] Step 1: Lower the locking cap tensioning device. The position of the locking cap tensioning device is determined by the matching of the positioning pin with the positioning hole on the gasket flange and the matching of the positioning cylinder with the center hole of the gasket.

[0016] Step 2: Observe the position of the hexagonal head of the tightening head and the notch on the bolt head. Use the long rod to rotate and align the tightening head so that the notch is aligned with the notch on the bolt head.

[0017] Step 3: Tighten the lower locking cap by expanding it so that it sits completely on the pad;

[0018] Step 4: Supply air to the cylinder to drive the gripper drive rod to move down, so that the gripper clamps and pad blocks are clamped and fixed.

[0019] Step 5: By using the long rod to screw down the tightening operating head, the nut pair is driven to press down and tighten. Then, the notched column squeezes and deforms the locking cap, causing it to embed into the notch in the bolt head, thus achieving the function of tightening and preventing loosening.

[0020] The beneficial effects of this invention are as follows: It utilizes a remote long-rod operation for screwing, positioning, alignment, and downward tightening, enabling remote operation of the pad locking cap. A specialized device integrating positioning of the tightening tool, screwing and positioning of the tightening head, clamping and fixing, and downward tightening is employed, achieving integrated underwater remote tightening of the pad locking cap and simplifying the process steps. Attached Figure Description

[0021] Figure 1 Diagram showing the composition of the pad blocks;

[0022] Figure 2 This is a structural diagram of the locking cap tensioning mechanism;

[0023] Figure 3 Installation diagram for the locking cap tensioning mechanism;

[0024] Figure 4 Diagram showing the operation of the locking cap tensioning mechanism;

[0025] Figure 5 For clamping and installation diagram;

[0026] Figure 6 This is a diagram showing the downward pressure and tightening.

[0027] Figure 7 This is a structural diagram of the expansion head.

[0028] In the diagram: 1. Pad; 12. Bolt; 11. Locking cap; 2. Locking cap tensioning device; 3. Long rod; 21. Positioning pin; 22. Positioning cylinder; 23. Clamping claw; 24. Alignment and tightening operating head; 25. Tensioning head; 26. Downward tensioning operating head; 27. Disc; 28. Downward nut; 231. Clamping claw drive rod; 232. Clamping cylinder; 251. Positioning hexagonal head; 252. Notched column; 253. Compression spring. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] To address the wear issue of the thermal insulation sleeve during nuclear reactor power operation, a special mitigation pad was designed and installed on the upper in-core component control rod guide tube at the corresponding position of the thermal insulation sleeve. This supports the thermal insulation sleeve, separating its end from the tube seat to prevent the end from rubbing against the CRDM tube seat. At the same time, it adds positioning at the lower part of the flared end to reduce radial vibration and wear.

[0031] The shim is secured to the guide tube cover plate with three bolts. Because the internal components of the reactor require a reliable mechanical anti-loosening locking structure, a mature locking cap anti-loosening design is used for these three bolts. One side of the locking cap is fixed to the shim, and the other side is fixed to the bolt, thus preventing loosening. The locking cap is secured to the bolt by creating three notches on the bolt head. The locking cap is then compressed and deformed, expanding into the notches to prevent rotation. This compression and tightening of the locking cap must be performed remotely underwater after the shim bolts are tightened.

[0032] This invention provides a device and method for remotely tightening the locking cap of the gasket in a heat insulation sleeve, the technical solution of which is as follows:

[0033] 1) For the installation and positioning of the tightening tool, positioning is achieved by the positioning cylinder engaging with the center hole of the pad and the positioning pin engaging with the process mounting hole on the pad.

[0034] 2) For the circumferential positioning of the tightening head, bolt, and locking cap, the head of the tightening head is designed with an external hexagonal structure. By operating the rotating long rod, the external hexagonal structure is inserted into the internal hexagonal hole of the bolt to position the tightening head.

[0035] 3) To tighten the locking cap, three cylinders are used to fit with three notches on the bolt head, which compresses and deforms the locking cap.

[0036] 4) To address the issue of extrusion pressure, a nut and screw pair structure is adopted. Rotating the operating rod drives the screw pair to press the nut down, thereby deforming the locking cap.

[0037] like Figure 1 As shown, the pad 1 that needs to be locked to prevent loosening consists of a bolt 12 and a locking cap 11. The present invention is to lock and fix the locking cap 11 and the bolt 12 to prevent loosening.

[0038] A device for remotely tightening the locking cap of a heat insulation sleeve includes a locking cap tightening device 2 and a long rod 3, wherein the long rod 3 is used for remote operation by personnel above a water tank.

[0039] The function of the locking cap expansion device 2 is to tighten the locking cap 11 and bolt 12 after the pad 1 is installed. The locking cap expansion device 2 is used when the pad 1 has been secured with bolt 12, leaving only the locking cap 11 unsecured. The function of the locking cap expansion device 2 is to lock the locking cap 11 remotely.

[0040] like Figure 2 As shown, the locking cap tensioning device 2 includes a positioning pin 21, a positioning cylinder 22, a clamping claw 23, an alignment and tightening operating head 24, a tensioning head 25, a downward tensioning operating head 26, a disc 27, and a downward nut 28.

[0041] The positioning pin 21 is fixed on the disc 27, and the positioning cylinder 22 is the central component of the locking cap expansion device 2. The positioning pin 21 and the positioning cylinder 22 respectively cooperate with the flange process hole and the center hole of the pad block 1 to play a positioning role.

[0042] Three gripping claws 23 are fixed to the positioning cylinder 22 by pins and can rotate around the pins.

[0043] The alignment and tightening operation head 24 consists of 3 parts, which are evenly distributed on the disc 27. There is no constraint in the hole, and it can be rotated by the long rod 3, or it can be moved up and down between the pressing nut 28 and the disc 27.

[0044] The tightening head 25 is fixed at the lower end of the alignment and screwing operating head 24 and is the direct functional component for the locking operation. It can rotate and move up and down together with the alignment and screwing operating head 24.

[0045] The downward tightening operating head 26 is fixed to the disc 27 by a support base and can rotate under the drive of the long rod 3. Its lower end is a stud structure that mates with the downward tightening nut 28 to form a threaded pair. When the downward tightening operating head 26 rotates, it drives the downward tightening nut 28 to move up and down. When the downward tightening nut 28 moves downward, it drives the tightening head 25 to move downward, thereby tightening the locking cap 11.

[0046] The positioning pin 21 is a cylindrical shape with a tapered guide and is fixed on the disc 27 of the whole device. Its function is to be inserted into the installation process hole on the gasket flange and cooperate with the positioning cylinder 22 to realize the positioning of the locking cap expansion device 2 on the gasket 1.

[0047] The positioning cylinder 22 is located at the center of the locking cap tensioning device 2, and is inserted into the center hole of the guide cylinder cover plate through the center hole of the pad 1 to play a centering role.

[0048] There are three gripping claws 23, which are evenly mounted on the positioning cylinder 22 via pins and can rotate around the pins to fix them to the pad. The gripping and releasing of the gripping claws 23 are achieved by the gripping claw drive rod 231 and the gripping cylinder 232. When the gripping cylinder 232 is supplied with air from the lower part, the gripping claw drive rod 231 moves upward, and through the wedge-shaped surface of the gripper, it drives the gripper 23 to retract and release; when the gripping cylinder 232 is supplied with air from the upper part, the gripping claw drive rod 231 moves downward, and through the wedge-shaped surface of the gripper, it drives the gripper 23 to be opened, achieving clamping and fixing with the inner conical surface of the pad.

[0049] Three gripping claws 23 are fixed to the positioning cylinder 22 by pins and can rotate around the pins. A gripping cylinder 232 is fixed to the upper end of the positioning cylinder 22 and is connected to the gripping claw drive rod 231 through a cylinder piston, forming a whole. The lower end of the gripping claw drive rod 231 contacts the wedge-shaped working surface of the gripping claw 23, and the opening and closing of the gripping claw is achieved through the wedge-shaped surface contact.

[0050] The aligned screwing operation head 24 has a tapered outer square structure at the top, which cooperates with the inner square of the long rod 3 to rotate the tightening head 25.

[0051] The alignment and tightening operation head 24 consists of 3 parts, which are evenly distributed on the disc 27. There is no constraint in the hole, and it can be rotated by the long rod 3, or it can be moved up and down between the pressing nut 28 and the disc 27.

[0052] The tightening head 25 is a key functional component of the locking cap tightening device 2. It consists of a positioning hexagonal head 251, a notched post 252, and a compression spring 253. The positioning hexagonal head 251 is limited to axial vertical movement by the keyway in the mounting hole. The compression spring 253 provides downward pressure to maintain the fit between the positioning hexagonal head 251 and the hexagonal countersunk groove inside the bolt 12. The positioning hexagonal head 251 can extend and retract under the action of the spring force above. The hexagonal fit between the positioning hexagonal head 251 and the bolt 12, through the positional relationship of the components of the tightening head 25, achieves the positioning of the notched post 252 and the notch of the bolt 12.

[0053] The downward pressure tightening operating head 26 is a rotating component that is driven to rotate by the long rod 3. Its lower end is a threaded pair. The rotation of the screw drives the pressure plate to move up and down. When it moves downward, it presses down on the rotating tightening head 25. The notched column 252 presses down and drives the locking cap 11 to deform towards the notch of the bolt 12, thereby achieving locking.

[0054] A method for remotely tightening the locking cap of a gasket in an insulation sleeve includes the following steps:

[0055] Step 1: Lower the locking cap tensioning device 2. The position of the locking cap tensioning device 2 is determined by the engagement of the positioning pin 21 with the positioning hole on the gasket flange and the engagement of the positioning cylinder 22 with the center hole of the gasket.

[0056] Step 2: Observe the position of the positioning hexagonal head 251 of the tightening head 25 and the notch on the head of the bolt 12. Rotate the long rod 3 to align the tightening head 24, so that the notch post 252 is aligned with the notch on the head of the bolt 12.

[0057] Step 3: Tighten the lower locking cap expansion device 2 so that it sits completely on the pad.

[0058] Step 4: Supply air to cylinder 232 to drive the gripper drive rod 231 to move down, so that the gripper 23 is clamped and fixed to the pad block 1.

[0059] Step 5: By screwing down the tightening operating head 26 through the long rod 3, the nut pair is driven to press down and align with the screwing operating head 24, thereby pressing down the tightening head 25, and then the notched column 252 squeezes and deforms the locking cap 11, so that it is embedded in the notch of the bolt head 12, which plays the role of tightening and preventing loosening.

Claims

1. A device for remotely tightening the locking cap of a gasket in a heat insulation sleeve, characterized in that: It includes a locking cap tensioning device and a long rod. The long rod is used for remote operation above the water tank. The locking cap tensioning device includes a positioning pin, a positioning cylinder, clamping claws, an alignment and screwing operation head, a tensioning head, and a downward pressure tensioning operation head. There are three clamping claws, which are evenly installed on the positioning cylinder by means of a pin shaft and can rotate around the pin shaft to fix them to the pad block. The clamping and releasing of the gripper is achieved through the gripper drive rod and the gripper cylinder. When the lower part of the gripper cylinder is supplied with air, the gripper drive rod moves upward and drives the gripper to retract and release through contact with the wedge-shaped surface of the gripper. When the upper part of the gripper cylinder is supplied with air, the gripper drive rod moves downward and drives the gripper to be opened through contact with the wedge-shaped surface of the gripper, thereby achieving clamping and fixing with the inner conical surface of the pad. The tightening head includes a positioning hexagonal head and a notched post. The positioning hexagonal head achieves extension and retraction through the action of the upper spring force. The positioning hexagonal head fits into the inner hexagon of the bolt. Through the positional relationship of the components of the tightening head, the notched post is positioned relative to the bolt notch. The aforementioned pressure tightening operating head is a rotating component driven to rotate by a long rod. Its lower end is a threaded pair, which drives the pressure plate to move up and down through the rotation of the screw. When moving downward, it presses down on the rotating tightening head, and the notched column presses down to drive the locking cap to deform towards the notch of the bolt, thereby achieving locking.

2. The device for remotely tightening the locking cap of the gasket in a heat insulation sleeve as described in claim 1, characterized in that: The positioning pin is cylindrical with a tapered guide. It is inserted into the installation process hole on the gasket flange and cooperates with the positioning cylinder to realize the positioning of the locking cap tightening device on the gasket.

3. The device for remotely tightening the locking cap of the gasket in a heat insulation sleeve as described in claim 1, characterized in that: The positioning cylinder is located at the center of the locking cap tensioning device, and is inserted into the center hole of the guide cylinder cover plate through the center hole of the pad to play a centering role.

4. The device for remotely tightening the locking cap of the gasket in a heat insulation sleeve as described in claim 1, characterized in that: The upper end of the alignment and tightening operating head has a tapered outer square structure, which cooperates with the inner square of the long rod to achieve the function of rotating the tightening head.

5. A method for remotely tightening the locking cap of a gasket in a heat insulation sleeve, using the apparatus as described in any one of claims 1 to 4, characterized in that... Includes the following steps: Step 1: Lower the locking cap tensioning device. The position of the locking cap tensioning device is determined by the matching of the positioning pin with the positioning hole on the gasket flange and the matching of the positioning cylinder with the center hole of the gasket. Step 2: Observe the position of the hexagonal head of the tightening head and the notch on the bolt head. Rotate the long rod to align the tightening head with the notch on the bolt head. Step 3: Lower the locking cap tensioning device so that it sits completely on the pad; Step 4: Supply air to the cylinder to drive the gripper drive rod to move down, so that the gripper clamps and pad blocks are clamped and fixed. Step 5: By using the long rod to screw down the tightening operating head, the nut pair is driven to press down and tighten. Then, the notched column squeezes and deforms the locking cap, causing it to embed into the notch in the bolt head, thus achieving the function of tightening and preventing loosening.

Images