A tool and method for handling a nuclear power main pump seal chamber bolt sticking failure

Abstract

The application provides a processing tool and method for the jamming failure of a nuclear power main pump sealing chamber bolt, comprising a tool platform, a plurality of tool bolts for supporting the tool platform are arranged on the tool platform; the tool bolts are fixed to the tool platform through penetrating screws and fixed nuts arranged at the top ends of the tool bolts, the bottom ends of the tool bolts are fixed and penetrate the sealing chamber, the bottom ends of the tool bolts are also fixed with heat shield flanges; a magnetic drill is arranged on the upper side of the tool platform, the magnetic drill penetrates the tool platform and corresponds to the jammed bolt, a plurality of equal height blocks are arranged on the lower side of the tool platform, the equal height blocks are fixed to the outer sides of the tool bolts, and pads are arranged on the equal height blocks; the pads are fixed between the equal height blocks and the sealing chamber. The application prevents irreversible damage to the main pump sealing chamber and the heat shield flange, and causes significant economic losses.

Description

A tool and method for handling bolt jamming in the sealing chamber of a nuclear power plant main pump. Technical Field

[0001] This invention relates to the field of troubleshooting technology for bolts in the sealing chamber of nuclear power plant main pumps, and in particular to a tool and method for dealing with bolt jamming in the sealing chamber of nuclear power plant main pumps. Background Technology

[0002] The mating surface between the main pump's heat shield flange and the No.1 sealing chamber employs static sealing technology, using a basic spiral wound gasket made of specially heat-treated stainless steel strip and graphite spiral composite. Sixteen hollow No.1 sealing chamber bolts are evenly distributed circumferentially for fastening. The main pump's No.1 sealing chamber bolts are rolled threads, fully screwed in, and are integrally forged from alloy steel. Hot tightening technology is used during installation and adjustment, with the bolt's thermal elongation ultimately controlling the cold-state bolt tightening torque. During bolt disassembly and replacement, both the bolts and bolt holes undergo high-standard cleanliness checks, and high-quality thread-locking agents such as Loctite N5000 or N7000 are used multiple times to thoroughly treat the threads. This bolt jamming failure occurred for the first time in China during the replacement of internal components of the sealing chamber during a refueling overhaul of the unit. The faulty bolt is located within the main pump coupling chamber, at the opening of the nuclear island's primary loop, near areas with radioactive aerosols and significant surface radioactive contamination. Using the conventional method of removing broken wires may cause irreversible damage to the No.1 sealing chamber and heat shield flange of the main pump, resulting in significant economic losses and posing numerous major risks such as industrial safety, radiation protection, foreign object protection, and damage to major equipment. Summary of the Invention

[0003] The purpose of this invention is to provide a tool and method for handling bolt jamming in the sealing chamber of a nuclear power plant main pump, and to solve the technical problem of how to prevent irreversible damage to the main pump sealing chamber and heat shield flange, which could lead to significant economic losses.

[0004] On the one hand, a tool for handling bolt jamming faults in the sealing chamber of a nuclear power plant main pump is provided, including:

[0005] A tooling platform, on which multiple tooling bolts are provided for supporting the tooling platform;

[0006] The tooling bolt is fixed to the tooling platform by a through bolt and a fixing nut at its top end, the bottom end of the tooling bolt is fixed and passes through the sealing chamber, and the bottom end of the tooling bolt is also fixed to the heat shield flange;

[0007] A magnetic drill is installed on the upper side of the tooling platform. The magnetic drill penetrates the tooling platform and corresponds to the bolt with the jamming fault. Multiple leveling blocks are installed on the lower side of the tooling platform. The leveling blocks are fixed to the outside of the tooling bolt. A pad is also installed on the leveling block.

[0008] The pad is fixed between the level block and the sealing chamber.

[0009] Preferably, the tooling platform is plate-shaped.

[0010] A magnetic drill is installed in the middle of the device, and the bottom of the magnetic drill is fixed to the tooling platform.

[0011] Multiple fixing through holes are provided on both sides, and the fixing through holes are penetrated by the top of the tooling bolt.

[0012] Preferably, the tooling bolt has a fixing thread and a through thread at its top, and a limiting block is provided on the bottom side of the fixing thread.

[0013] When the tooling bolt is inserted into the fixing through hole, the limiting block engages with the lower side of the tooling platform, and the fixing thread engages with the upper side of the tooling platform.

[0014] The fixing nut is fixed to the upper side of the tooling platform by the fixing thread, and the through screw can be rotated to adjust the horizontal height of the tooling platform.

[0015] Preferably, the contour block has a circular hole, and the contour block is fitted onto the tooling bolt through the circular hole. The top of the contour block is attached to the lower side of the tooling platform, and the bottom of the contour block is attached to the outer wall of the sealing chamber.

[0016] Preferably, the top of the heat shield flange is provided with a plurality of bolt holes corresponding to the tooling bolts, and the bolt holes are fitted onto the bottom end of the tooling bolts.

[0017] On the other hand, a method for handling bolt jamming in the sealing chamber of a nuclear power plant main pump is also provided, which is implemented based on the tool for handling bolt jamming in the sealing chamber of the nuclear power plant main pump, including:

[0018] When a jamming fault is found in the main pump sealing chamber bolts, the area where the faulty bolts are located shall be pre-treated; wherein, the pre-treatment includes at least foreign object prevention control and radiation protection control;

[0019] The processing tool is positioned at the main pump sealing chamber to obtain parameter information of the main pump sealing chamber and the bolt that is stuck. The processing tool is then adjusted based on the obtained parameter information.

[0020] After the processing tool is adjusted, use a magnetic drill to break down the bolt and threaded part of the jammed bolt.

[0021] Preferably, the pretreatment of the area where the faulty bolt is located specifically includes,

[0022] The gaps and bolt holes at the mechanical shaft seal installation openings are sealed using pre-set sealing tools to establish a foreign object control zone. Throughout the process, all items and tools carried by personnel entering and exiting are registered and verified.

[0023] A pollution survey was conducted on the main pump coupling chamber where the bolts causing the jamming fault were located. Surfaces identified as having radiation contamination were cleaned. At the same time, the mechanical shaft seal installation openings previously installed in the foreign object protection control area were checked to ensure that they were completely sealed and that no new radiation contaminants could escape.

[0024] Preferably, adjusting the processing tool based on the acquired parameter information specifically includes:

[0025] Based on the obtained parameter information, select the corresponding height level block, pad block and magnetic drill, fix them with through screws, and fix them to the position of the sealing chamber with the tooling bolts and the fixing nuts;

[0026] The magnetic drill is fixed to the bolt corresponding to the jamming fault on the tooling platform.

[0027] Preferably, it also includes,

[0028] After the threaded hole of the jammed bolt has been dismantled and cleaned, an endoscopic inspection and photographs are performed on the jammed threaded hole, and a colloid molding of the threaded bottom hole is carried out at the same time.

[0029] Preferably, it also includes,

[0030] The presence of tooth damage in the bottom thread is determined by endoscopic examination. If tooth damage is found, an assessment is conducted based on the tooth damage information, and the bolt is repaired according to the assessment results.

[0031] In summary, implementing the embodiments of the present invention has the following beneficial effects:

[0032] This invention provides a tool and method for handling bolt jamming in the sealing chamber of a nuclear power plant main pump. Given the confined space of the main pump coupling chamber, it establishes a safe and efficient bolt handling tool and corresponding method. While meeting safety protection requirements, it ensures that the mobility of personnel can meet maintenance needs. The results of dismantling the jammed threads are evaluated to determine whether they meet the requirements for reassembly, long-term operation, and frequent disassembly and reassembly during subsequent major overhauls of the unit. This prevents irreversible damage to the main pump sealing chamber and heat shield flange, thus avoiding significant economic losses. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0034] Figure 1 is a schematic diagram of a tool for handling bolt jamming in the sealing chamber of a nuclear power plant main pump according to an embodiment of the present invention.

[0035] Figure 2 is a schematic diagram of the main process of a method for handling bolt jamming in the sealing chamber of a nuclear power plant main pump according to an embodiment of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0037] Figure 1 shows a schematic diagram of an embodiment of a tool for handling bolt jamming in the sealing chamber of a nuclear power plant main pump provided by the present invention. This embodiment includes:

[0038] Tooling platform 4, on which a plurality of tooling bolts 3 are provided for supporting the tooling platform 4;

[0039] The tooling bolt 3 is fixed to the tooling platform 4 by a through screw 1 and a fixing nut 2 provided at its top end. The bottom end of the tooling bolt 3 is fixed and passes through the sealing chamber 6. The bottom end of the tooling bolt 3 is also fixed to the heat shield flange 7.

[0040] A magnetic drill 8 is provided on the upper side of the tooling platform 4. The magnetic drill 8 penetrates the tooling platform 4 and corresponds to the bolt 9 that is stuck. A plurality of leveling blocks 5 are provided on the lower side of the tooling platform 4. The leveling blocks 5 are fixed to the outside of the tooling bolt 3. A pad block 10 is also provided on the leveling block 5.

[0041] The pad 10 is fixed between the level block 5 and the sealing chamber 6.

[0042] In a specific embodiment, the tooling platform 4 is plate-shaped, with a magnetic drill 8 disposed in the middle. The bottom of the magnetic drill 8 is fixed to the tooling platform 4, and multiple fixing through holes are provided on both sides of the magnetic drill 8. The fixing through holes are penetrated by the top of the tooling bolt 3.

[0043] Specifically, the tooling bolt 3 is provided with a fixing thread and a through screw 1 at its top, and a limiting block is provided on the bottom side of the fixing thread. When the tooling bolt 3 is inserted into the fixing through hole, the limiting block is engaged with the lower side of the tooling platform 4, and the fixing thread is engaged with the upper side of the tooling platform 4. The fixing nut 2 is fixed to the upper side of the tooling platform 4 by the fixing thread, and the through screw 1 can be rotated to adjust the horizontal height of the tooling platform 4.

[0044] The contour block 5 has a circular hole, and the contour block 5 is fitted onto the tooling bolt 3 through the circular hole. The top of the contour block 5 is attached to the lower side of the tooling platform 4, and the bottom of the contour block 5 is attached to the outer wall of the sealing chamber 6.

[0045] The top of the heat shield flange 7 is provided with a plurality of bolt holes corresponding to the tooling bolts 3, and the bolt holes are fitted onto the bottom end of the tooling bolts 3.

[0046] As shown in Figure 2, a method for handling the jamming fault of the 6 bolts in the sealing chamber of a nuclear power plant main pump is implemented based on the tool for handling the jamming fault of the 6 bolts in the sealing chamber of the nuclear power plant main pump, including:

[0047] Step S1: When a jamming fault is found in the main pump sealing chamber 6 bolts, pre-treatment is performed on the area where the faulty bolt is located. This pre-treatment includes at least foreign object control and radiation protection control. Understandably, this is preparation before handling the bolt jamming fault. To dismantle the jammed bolt, the most suitable tool is a magnetic drill 8. Only a sufficiently large carbon steel surface that can be magnetically attracted and is completely perpendicular to the jammed bolt is needed to fix the magnetic drill 8. Due to the limited space, the principle is to fabricate a carbon steel plate of a specific size based on the actual dimensions of the site and the attraction area of ​​the magnetic drill 8. Simultaneously, two normal bolts adjacent to the jammed bolt are used for tightening and positioning, ensuring that the magnetic drill 8 can be stably installed directly above the jammed bolt. The foreign object control methods at this stage are as follows: All bolt holes, mechanical shaft seal installation openings, and flange gaps that could potentially enter the machining dust are sealed. For large mechanical shaft seal installation openings, PTFE (polytetrafluoroethylene) sheets are used to create a self-made foreign object cover, which is then sealed with white tape specific to the nuclear island control area. Small gaps and bolt holes are directly sealed with white tape. A foreign object control zone is established. Throughout the process, all items and tools carried by personnel entering and exiting the zone must be registered and verified, ensuring no items are missed to prevent foreign objects from falling in. A high-powered vacuum cleaner is also prepared as a backup. The industrial safety and radiation protection control methods at this stage include: conducting a comprehensive contamination survey of the main pump coupling chamber where the jamming bolts are located; cleaning any surfaces that have been contaminated with radiation to ensure there are no suspended radioactive contaminants; and verifying that the sealing of the mechanical shaft seal installation openings performed in the previous foreign object control measures is completely sealed to ensure no new radioactive contaminants escape. Provided that there is no significant risk of radiation contamination to personnel, prepare a basic 7-piece set for operations in the controlled area, as well as additional protective equipment such as air masks / full-face masks, paper clothing, plastic shoe covers, and latex shoe covers.

[0048] Step S2: Position the processing tool at the main pump sealing chamber 6, obtain parameter information for the main pump sealing chamber 6 and the bolt 9 that is stuck, and adjust the processing tool according to the obtained parameter information. Understandably, the working height of the tooling platform 4 and magnetic drill 8 is adjusted by using 63mm height leveling blocks 5 and C-shaped pads 10, and fixed with through bolts. The special tool is then fixed to the sealing chamber 6 using tooling bolts 3 and fixing nuts 2. The magnetic drill 8 is fixed at the corresponding position on the tooling platform 4, and the magnetic drill 8 is used to break open the bolt and nut portion of the stuck sealing chamber 6.

[0049] Foreign object control measures at this stage: Use white plastic bags to appropriately cordon off areas prone to debris from demolition. Immediately after demolition, use a vacuum cleaner to clean up debris and thoroughly clean tools. Simultaneously, the surfaces of any additional protective equipment worn by personnel, such as face masks / full-face masks, paper gowns, plastic shoe covers, and latex shoe covers, must be cleaned of welding slag or replaced to prevent the presence of small debris. After personnel and tools have been removed and radiation protection checks have been completed, dismantle the previous foreign object control measures to prepare for the subsequent dismantling of sealed chamber 6.

[0050] Industrial safety and radiation protection control methods at this stage: Contaminated and uncontaminated tools must be stored separately and must not be mixed; all personnel must wear TLD and EPD for radiation dose monitoring. For cutting and grinding operations, an additional DMC3000 should be worn to avoid false doses. If the radiation dose exceeds the limit, evacuate immediately, and radiation protection personnel should adjust the radiation dose limit or replace the operator according to regulations; immediately after demolition, conduct a comprehensive radiation contamination survey of personnel and the site to remove suspended radioactive contaminants. When using the magnetic drill 8, control the drilling depth at each step to avoid splashing. Keep personnel's faces as far away from the drill bit as possible to avoid injury from flying debris. Prevent gloves, paper clothing, and other items from being caught in the magnetic drill 8. Securely fix the power socket of the magnetic drill 8 and assign a dedicated person to manage it, responding promptly to the power on / off requests from the magnetic drill 8 operator.

[0051] Step S3: After the processing tool is adjusted, use the magnetic drill 8 to break the bolt and thread of the jammed bolt 9. Understandably, after removing the nut from the flange bolt of the sealing chamber 6, lift the flange of the sealing chamber 6. Adjust the working height of the tooling platform 4 and the magnetic drill 8 by using 100mm height leveling blocks 5 and C-shaped pads 10, and fix them with through bolts. Secure the special tool to the position of the heat shield flange 7 using tooling bolts 3 and fixing nuts 2. Fix the magnetic drill 8 to the corresponding position on the tooling platform 4, and use the magnetic drill 8 to break the bolt and thread of the jammed sealing chamber 6 bolt. The jammed internal thread on the heat shield flange 7 is the most critical part of the bolt breaking process. No additional damage should be caused during the breaking process, otherwise it will result in significant equipment and economic losses. Therefore, when selecting the magnetic drill 8 bit, a strategy of gradually increasing the drill bit size should be followed. Each time the drill bit is changed, the drill bit centering check should be performed again. The magnetic drill 8 should not be used near the threaded area; instead, use a manual thread razor or other tools for meticulous and gradual removal.

[0052] The foreign object control method for this stage is as follows: After the flange of the sealing chamber 6 is removed, the opening should be resealed immediately according to the foreign object control method of the first stage, without omission. The foreign object control requirements during the secondary demolition process of the magnetic drill 8 are completely consistent with those of the second stage.

[0053] The industrial safety and radiation protection control methods for this stage are as follows: Immediately after removing the flange of the sealed chamber 6, clean up any water stains and, at the same time, re-implement industrial safety and radiation protection risk control measures according to the methods used in the first stage. The industrial safety and radiation protection requirements during the secondary demolition process using the magnetic drill 8 are completely consistent with those in the second stage.

[0054] Specifically, the pretreatment of the area where the faulty bolt is located includes sealing the gaps and bolt holes at the mechanical shaft seal installation opening with a pre-set sealing tool, establishing a foreign object prevention control zone, and registering and verifying all items and tools carried by all personnel entering and exiting the area throughout the process; conducting a pollution survey of the main pump coupling chamber where the jammed bolt 9 is located, cleaning the surfaces identified as having radiation contamination, and checking whether the sealing of the mechanical shaft seal installation opening in the previous foreign object prevention control zone is completely sealed to ensure that no new radiation contaminants escape.

[0055] The adjustment of the processing tool based on the acquired parameter information specifically includes selecting a height equalization block 5, a pad block 10, and a magnetic drill 8 of corresponding height based on the acquired parameter information, fixing them with a through screw 1, and fixing them to the sealing chamber 6 with the tooling bolt 3 and the fixing nut 2; fixing the magnetic drill 8 to the bolt 9 of the tooling platform 4 corresponding to the jamming fault.

[0056] In this embodiment, after the threaded hole of the jammed bolt 9 has been cleaned and dismantled, an endoscopic inspection and photographing of the jammed threaded hole are performed, and a colloid molding of the threaded bottom hole is carried out simultaneously. The endoscopic inspection determines whether there is tooth damage to the bottom thread. If tooth damage is found, an assessment is conducted based on the tooth damage information, and the bolt is repaired according to the assessment results. Understandably, thread inspection and repair are performed. The method is as follows: After confirming that the threaded hole of the jammed bolt has been cleaned and dismantled, an endoscopic inspection and photographing of the jammed threaded hole are performed, and a colloid molding of the threaded bottom hole is carried out simultaneously. If tooth damage is found in the bottom thread, the tooth damage information is reported to the main pump manufacturer, who then conducts a usability assessment. Based on the manufacturer's assessment requirements, a tap repair or other solutions are implemented; if the assessment fails, an M52 to M55 enlargement repair is performed.

[0057] In summary, implementing the embodiments of the present invention has the following beneficial effects:

[0058] This invention provides a tool and method for handling bolt jamming in the sealing chamber of a nuclear power plant main pump. Given the confined space of the main pump coupling chamber, it establishes a safe and efficient bolt handling tool and corresponding method. While meeting safety protection requirements, it ensures that the mobility of personnel can meet maintenance needs. The results of dismantling the jammed threads are evaluated to determine whether they meet the requirements for reassembly, long-term operation, and frequent disassembly and reassembly during subsequent major overhauls of the unit. This prevents irreversible damage to the main pump sealing chamber and heat shield flange, thus avoiding significant economic losses.

[0059] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for handling bolt jamming in the sealing chamber of a nuclear power plant main pump, implemented using a tool for handling bolt jamming in the sealing chamber of a nuclear power plant main pump, characterized in that... include: When a jamming fault is detected in the main pump sealing chamber bolt, pretreatment is performed on the area where the faulty bolt is located. This pretreatment includes at least foreign object control and radiation protection control. The processing tool is positioned at the main pump sealing chamber to obtain parameter information about the main pump sealing chamber and the jammed bolt, and the processing tool is adjusted based on this information. After adjustment, a magnetic drill is used to dismantle the bolt and threaded portion of the jammed bolt. Specifically, the pretreatment of the area where the faulty bolt is located includes sealing the gaps and bolt holes at the mechanical shaft seal installation opening using a pre-set sealing tool to establish a foreign object control zone. Throughout this process, all items and tools carried by personnel entering and exiting the area are registered and verified. A pollution survey is conducted on the main pump coupling chamber where the jammed bolt is located. Surfaces identified as having radiation contamination are decontaminated, and the sealing of the mechanical shaft seal installation opening in the previous foreign object control zone is checked to ensure complete sealing and prevent the escape of new radiation contaminants.

2. The processing method as described in claim 1, characterized in that, The tool for handling bolt jamming in the sealing chamber of the nuclear power plant main pump includes: a tooling platform with multiple tooling bolts for supporting the platform; the tooling bolts are fixed to the tooling platform by through bolts and nuts at their top ends, and the bottom ends of the tooling bolts are fixed to and pass through the sealing chamber, with a heat shield flange also fixed to the bottom end; a magnetic drill is installed on the upper side of the tooling platform, passing through the platform and corresponding to the jammed bolt; multiple leveling blocks are installed on the lower side of the tooling platform, fixed to the outside of the tooling bolt, and spacers are installed on the leveling blocks; the spacers are fixed between the leveling blocks and the sealing chamber; and the adjustment of the tooling according to the acquired parameter information specifically includes: selecting leveling blocks, spacers, and a magnetic drill of corresponding heights according to the acquired parameter information, fixing them with through bolts, and fixing them to the sealing chamber position with the tooling bolts and nuts; fixing the magnetic drill to the tooling platform corresponding to the jammed bolt.

3. The processing method as described in claim 2, characterized in that, This also includes, after the threaded hole of the jammed bolt has been broken open and cleaned, performing an endoscopic inspection and taking pictures of the jammed threaded hole, and simultaneously implementing a colloid molding of the threaded bottom hole.

4. The processing method as described in claim 3, characterized in that, It also includes determining whether there is tooth damage in the bottom thread through endoscopic examination. If there is tooth damage in the bottom thread, an assessment is made based on the tooth damage information, and the bolt is repaired based on the assessment results.

5. The processing method as described in claim 2, characterized in that, The tooling platform is plate-shaped, with a magnetic drill set in the middle. The bottom of the magnetic drill is fixed to the tooling platform, and multiple fixing through holes are set on both sides of the magnetic drill. The fixing through holes are penetrated by the top of the tooling bolt.

6. The processing method as described in claim 5, characterized in that, The tooling bolt is provided with a fixing thread and a through thread at the top. A limiting block is provided on the bottom side of the fixing thread. When the tooling bolt is inserted into the fixing through hole, the limiting block is engaged with the lower side of the tooling platform, and the fixing thread is engaged with the upper side of the tooling platform. The fixing nut is fixed to the upper side of the tooling platform by the fixing thread, and the through thread can be rotated to adjust the horizontal height of the tooling platform.

7. The processing method as described in claim 6, characterized in that, The contour block has a circular hole inside, and the contour block is fitted onto the tooling bolt through the circular hole. The top of the contour block is attached to the lower side of the tooling platform, and the bottom of the contour block is attached to the pad block.

8. The processing method as described in claim 7, characterized in that, The top of the heat shield flange is provided with multiple bolt holes corresponding to the tooling bolts, and the bolt holes are fitted onto the bottom end of the tooling bolts.

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