Underwater repairing device and method for nuclear power plant pool steel lining defects

Abstract

The invention belongs to the technical field of nuclear power equipment maintenance, and particularly relates to an underwater repairing device and method for nuclear power plant pool steel lining defects. Comprising a coating cavity, a hanging seat is arranged at the top of the coating cavity, a lifting module is arranged in the coating cavity, a flexible shaft penetrates through the coating cavity and drives the lifting module to move, a gluing valve supporting plate is movably connected with the lifting module, a tension spring stretches out and draws back to limit movement between the gluing valve supporting plate and the lifting module, and a limiting wheel is installed on the gluing valve supporting plate and moves along a guide rail. The gluing valve is fixed to the gluing valve supporting plate, the glue mixing pipe is installed on the gluing valve, the gluing plate is connected with the gluing valve supporting plate, the A / B component glue injection connecting pipe and the air compressor connecting pipe are both arranged at the top of the coating cavity, the vacuum suction cup is fixed to the coating cavity, and the gas-liquid mixing pump connecting pipe is connected with the vacuum suction cup. The method has the advantages that the resin gel and the matched maintenance device are adopted for repairing, maintenance in the radioactive boron-containing water environment can be achieved, time is saved in the maintenance process, irradiation exposure is reduced, and the repairing effect is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nuclear power plant maintenance, and particularly relates to an underwater repair device and method for defects of a steel lining of a pool of a nuclear power plant. BACKGROUND

[0002] The main function of the spent fuel pool of a nuclear power plant covers the dual storage requirements of new fuel and spent fuel. New fuel assemblies need to be temporarily stored in the pool before being loaded into the reactor core, and spent fuel assemblies generated after operation need to continue to be stored in the pool until conditions are met for being transported to a reprocessing facility. Since the spent fuel continuously releases heat and generates radioactivity during the decay process, the spent fuel pool of the nuclear power plant is always filled with borated water to keep the spent fuel assemblies cool and provide a biological radiation shielding layer.

[0003] The spent fuel pool has a huge volume (more than 1800m 3 ), and is based on a concrete structure, with a surface covered by 3-6mm austenitic stainless steel plates. The steel plates are connected by welding to form a complete structure containing the borated water layer. As the service time accumulates, the possibility of leakage of the steel lining of the spent fuel pool increases gradually due to original defects of the weld, irradiation embrittlement, pitting corrosion, stress corrosion cracking, etc. The back of the butt weld of the pool wall and the bottom surface of the spent fuel pool is mostly a channel steel structure used as a drainage channel, and the channel steel is connected to collect and then discharged to the waste liquid treatment system through a leakage pipe. Leakage of the stainless steel lining not only leads to an increase in the amount of radioactive waste liquid to be treated and a decrease in the cooling effect of the spent fuel, but also causes a serious increase in the environmental dose in the plant and an increase in the risk of radiation exposure of personnel.

[0004] For the repair of defects of the steel lining of the spent fuel pool of the nuclear power plant, the currently used dry welding method is to remove the spent fuel and empty the pool, and then personnel directly enter the pool for repair. This method has a long repair preparation time and a high radiation risk for personnel.

[0005] Japan's Hitachi and Ishikawa Heavy Industry Company developed a spent fuel pool underwater remote control repair special machine, which installs a large beam on the edge of the spent fuel pool to carry the repair special machine system. The PCI company under Westinghouse Electric Company uses a small special machine to locally empty the water area to perform laser welding repair on the bottom plate of the spent fuel pool. The underwater fixed gas cover plate argon arc welding repair system developed by the China Nuclear Power Plant Operation Service Technology Co., Ltd. can realize underwater patch welding repair of the pool bottom plate. The Shanghai Nuclear Engineering Research and Design Institute developed underwater laser welding technology, which uses a movable gas cover to drain water and perform underwater welding in the emptied water area. Overall, the underwater welding technology has problems such as too large equipment volume, poor welding implementation, and unsatisfactory weld quality.

[0006] European research institutions such as EDF use the characteristics of high polymer water resistance, fast curing and the like to carry out underwater heating and plugging of the leakage points, and the scheme needs to consider: (1) important problems such as the curing conditions of the modified polymer, the influence degree on water quality, the degradation of mechanical properties, and the service life in the boron-containing underwater irradiation; (2) special repair devices and repair processes matched with the polymer. SUMMARY

[0007] The purpose of the present application is to provide an underwater repair device and method for defects of a nuclear power plant pool steel lining, which can satisfy the use of resin gel for quick plugging when the spent fuel pool steel lining leaks, and can solve the problem that the spent fuel pool of the nuclear power plant cannot be quickly repaired in the water and fuel assembly environment.

[0008] The technical scheme of the present application is as follows: An underwater repair device for defects of a nuclear power plant pool steel lining, comprising a coating cavity, a hanging seat is arranged at the top of the coating cavity, a lifting module is arranged inside the coating cavity, a flexible shaft passes through the coating cavity and drives the lifting module to move, a glue valve support plate is movably connected with the lifting module, a tension spring limits the movement between the glue valve support plate and the lifting module, a limiting wheel is installed on the glue valve support plate and moves along the guide rail, a glue valve is fixed on the glue valve support plate, a glue mixing pipe is installed on the glue valve, a glue coating plate is connected with the glue valve support plate, A / B component glue injection connecting pipes and air compressor connecting pipes are arranged at the top of the coating cavity, a vacuum chuck is fixed with the coating cavity, and a gas-liquid mixing pump connecting pipe is connected with the vacuum chuck.

[0009] Additional hanging seats are arranged at other positions of the coating cavity.

[0010] The repair gel is delivered to the glue valve through the A / B component glue injection connecting pipe, and compressed air is delivered to the inside of the coating cavity through the air compressor connecting pipe to exhaust water from the inside.

[0011] The vacuum chuck is fixed with the coating cavity through the vacuum chuck connecting foot.

[0012] The detachable cover plate is connected with the coating cavity to form a semi-sealed space, and after being detached, the internal components can be conveniently replaced.

[0013] The sealing rubber strip is installed at the window of the detachable cover plate.

[0014] The one-way valve is fixed on the detachable cover plate to drain water from the inside to the outside in one direction.

[0015] An underwater repair method for defects of a nuclear power plant pool steel lining, comprising the following steps:

[0016] Step 1: A / B components are caused to flow out from the glue valve and the glue mixing pipe in a mass ratio of 1.5:1 by automatic or manual tools, and the resin gel at the pipe opening is wiped clean to complete the pre-filling;

[0017] Step 2: The coating cavity is positioned to the defect position of the spent fuel pool by connecting the hanger seat with the crane, and the test support is used to simulate the pool wall and pool bottom position of the spent fuel pool;

[0018] Step 3: The vacuum chuck is vacuumized by starting the gas-liquid mixing pump, so that the coating cavity is adsorbed to the pool wall or pool bottom of the spent fuel pool;

[0019] Step 4: The air compressor is started to inject compressed air into the coating cavity, and after the water in the coating cavity is discharged from the bottom one-way valve, the injection of compressed air is stopped;

[0020] Step 5: The hand wheel is counterclockwise rotated to drive the soft shaft, so that the lifting module moves to the bottom of the guide rail, and the hand wheel is clockwise rotated to drive the soft shaft, so that the lifting module moves to the top of the guide rail, and the glue coating valve support plate, glue coating valve, glue mixing pipe and glue coating plate are also moved upward, and the glue coating of the defect position is completed;

[0021] Step 6: After the glue coating area completely covers the defect area, the glue coating valve is closed by operating the controller;

[0022] Step 7: When the lifting module approaches the limiting block, the limiting wheel also approaches the limiting block, and the glue coating valve support plate is counterclockwise rotated, so that the glue mixing pipe and glue coating plate are separated from the working surface;

[0023] Step 8: After waiting for an appropriate time, the gas-liquid mixing pump is turned off, and the vacuum chuck is separated from the pool wall or pool bottom;

[0024] Step 9: The coating cavity is taken out from underwater by the crane connected with the hanger seat, and the underwater gel coating work is completed.

[0025] The resin gel and the repair device of the present application have the advantages of high construction efficiency, wide application range and high reliability, and the specific advantages are as follows:

[0026] (1) the resin gel is made of two components A and B, and after mixing and hardening, the shear strength can reach 5MPa; (2) the gel time of the resin gel in normal temperature air is as short as 20 minutes, and the time for hardening to 70 Shore D is 3 hours; (3) the halogen content of the resin gel is extremely low, the F and Cl content in the bulk is less than 10ppm, and the precipitation ratio in boron water is less than 1%; (4) after the resin gel is soaked in 80℃, 2400ppm boron water for 144 days, the shear strength decreases by 10%; (5) after the resin gel is subjected to gamma irradiation at a dose rate of 1kGy and a cumulative dose of 0.8MGy, the shear strength does not decrease; 6) the repair device comprises a water surface part and a water under part. The water surface part mainly comprises an air-liquid mixing pump, an air compressor, a flexible shaft, a dispensing controller and a screw valve, etc. The water under part mainly comprises a vacuum chuck, a coating cavity and a glue coating equipment, etc. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A schematic view of the coating cavity adsorbed on a vertical wall surface;

[0028] Figure 2 A schematic view of the coating cavity structure Figure 1 ;

[0029] Figure 3 A schematic view of the coating cavity structure Figure 2 .

[0030] In the figure: 1 test support, 2 coating cavity, 3 hanging seat, 4 flexible shaft, 5 A / B component glue injection pipe, 6 air compressor connection pipe, 7 vacuum chuck, 8 vacuum chuck connecting foot, 9 air-liquid mixing pump connection pipe, 10 lifting module, 11 tension spring, 12 limit wheel, 13 glue coating valve support plate, 14 guide rail, 15 limit block, 16 glue coating valve, 17 glue mixing pipe, 18 glue coating plate, 19 detachable cover plate, 20 sealing rubber strip, 21 one-way valve. DETAILED DESCRIPTION

[0031] The application will be further described in detail below in combination with the drawings and specific embodiments.

[0032] The underwater repair device and method for defects of a nuclear power plant pool steel lining provided by the application, the device comprises a water surface part and a water under part. The water surface part mainly comprises an air-liquid mixing pump, an air compressor, a flexible shaft, a dispensing controller and a screw valve, etc. The water under part mainly comprises a vacuum chuck, a coating cavity and a glue coating equipment, etc. The method adopts resin gel and a matching repair device to repair defects of a steel lining weld and base metal generated in a service environment, and the resin gel comprises two components A and B.

[0033] As shown in 1 and 2, a kind of underwater repair device of nuclear power plant pool steel lining defect, including coating cavity 2, hanger 3, flexible shaft 4, A / B component glue injection pipe 5, air compressor connection pipe 6, vacuum chuck 7, vacuum chuck connecting foot 8, gas-liquid mixing pump connection pipe 9, lifting module 10, tension spring 11, limit wheel 12, glue valve support plate 13, guide rail 14, limit block 15, glue valve 16, glue mixing pipe 17, glue coating plate 18, detachable cover plate 19, sealing rubber strip 20 and one-way valve 21.

[0034] As shown in Figure 1 Coating cavity 2 is frame type structure, the top of coating cavity 2 is fixed with hanger 3, if necessary, hanger 3 can be additionally arranged at other positions of coating cavity 2. Figure 2 As shown in Lifting module 10 is fixed in coating cavity 2, flexible shaft 4 passes through coating cavity 2 and drives lifting module 10 to move, guide rail 14 is fixed on the two sides of lifting module 10, the leg of glue valve support plate 13 is fixed on lifting module 10, one end of tension spring 11 is fixed on the leg of glue valve support plate 13, the other end is fixed on the body of glue valve support plate 13, and the movement between glue valve support plate 13 and lifting module 10 is limited by stretching and contracting.Limit wheel 12 is installed on glue valve support plate 13 and moves along guide rail 14, when encountering limit block 15 at the two ends of guide rail 14, glue valve support plate 13 will act.Glue valve 16 is fixed on glue valve support plate 13, glue mixing pipe 17 is installed on glue valve 16, and glue coating plate 18 is connected to glue valve support plate 13.A / B component glue injection pipe 5 and air compressor connection pipe 6 are both arranged at the top of coating cavity 2, A / B component repair gel is transported to the two glue inlet interfaces of glue valve 16 through A / B component glue injection pipe 5 respectively, and compressed air is transported to the inside of coating cavity 2 through air compressor connection pipe 6 to discharge water from the inside.Vacuum chuck 7 is fixed with coating cavity 2 through vacuum chuck connecting foot 8.Gas-liquid mixing pump connection pipe 9 is connected with vacuum chuck 7 to adsorb vacuum chuck 7 at the work site.Detachable cover plate 19 is connected with coating cavity 2 to form a semi-sealed space, which can be easily replaced after being removed.Sealing rubber strip 20 is installed at the window of detachable cover plate 19.One-way valve 21 is fixed on detachable cover plate 19 to drain water from inside to outside.Coating cavity 2 is fixed on test support 1 through vacuum chuck 7, and test support 1 can be placed horizontally or vertically to verify whether the function of coating cavity 2 is normal.

[0035] The present application relates to a kind of underwater repair method of nuclear power plant pool steel lining defect, comprising the following steps:

[0036] Step 1: A / B component is made to flow out from glue valve 16, glue mixing pipe 17 by automatic or manual tool according to mass ratio 1.5:1.After wiping clean the resin gel of pipe opening, pre-filling is completed.

[0037] Step 2: Use a crane to connect the crane base 3 to position the coating chamber 2 to the defect location of the spent fuel pool. The test bracket 1 simulates the location of the spent fuel pool wall and bottom.

[0038] Step 3: Start the gas-liquid mixing pump to evacuate the vacuum suction cup 7 so that the coating cavity 2 is adsorbed onto the wall or bottom of the spent fuel pool.

[0039] Step 4: Start the air compressor and inject compressed air into the coating chamber 2. After the water inside the coating chamber 2 is discharged from the bottom one-way valve 21, stop injecting compressed air.

[0040] Step 5: Turn the handwheel counterclockwise to drive the flexible shaft 4, so that the lifting module 10 moves to the bottom of the guide rail 14. Turn the handwheel clockwise to drive the flexible shaft 4 to move the lifting module 10 to the top of the guide rail 14. The glue valve support plate 13, glue valve 16, glue mixing tube 17, and glue plate 18 also move upward at the same time to complete the glue coating at the defective location.

[0041] Step 6: After the glue coating area completely covers the defective area, the controller is operated to close the glue coating valve 16.

[0042] Step 7: When the lifting module 10 approaches the limit block 15, the limit wheel 12 also approaches the limit block 15, and the glue valve support plate 13 rotates counterclockwise, so that the glue mixing tube 17 and the glue coating plate 18 are separated from the working surface.

[0043] Step 8: After waiting for an appropriate time, turn off the gas-liquid mixing pump and separate the vacuum suction cup 7 from the pool wall or bottom.

[0044] Step 9: Use a crane to connect the hanging seat 3 to take the coating chamber 2 out from underwater to complete the underwater gel coating work.

[0045] Compared with existing dry welding and underwater welding, the present invention has the following characteristics:

[0046] (1) In dry welding technology and underwater welding technology, the welding area needs to be surface treated, and defects such as weld height and cracks are polished and debris is collected to improve welding quality; the patent of this invention does not require surface treatment.

[0047] (2) In dry welding technology, the spent fuel pool needs to remove the spent fuel and drain the pool; in underwater welding technology, the water is drained through the gas hood and hot air and protective gas are filled in to ensure that the working surface is dry and the protective atmosphere in the gas hood is maintained; the patent of the present invention can discharge the internal boron-containing water through the coating chamber, without the need for dehumidification and drying the working surface.

[0048] (3) The resin gel of the present invention can be applied over a large area, and the defect location requirement is low. Both dry welding and underwater welding require precise positioning of the defect location and the board placement.

[0049] (4) The resin gel of the present invention hardens spontaneously after mixing, without the need for additional heat sources, does not generate new heat-affected zones, and does not cause secondary deformation of the steel lining. Dry welding and underwater welding both require high-power heat sources for tack welding.

[0050] (5) The coating cavity of the present invention is compact in structure, light in weight, and high in reliability compared with the gas cover of underwater welding.

[0051] (6) The resin gel storage bin of the present invention has a large volume and is located on the water surface, and can be filled with resin gel online during the repair process.

[0052] (7) The coating gun nozzle of the present invention is made of PE hard material, which can adapt to different shapes, sizes, and glue output parameters.

[0053] (8) The repair process of the present invention is simplified and time-saving, and automatic or manual operation can be selected during repair.

Claims

1. An underwater repair device for defects in the steel lining of a nuclear power plant pool, characterized by: It includes a coating chamber, a hanging seat is provided on the top of the coating chamber, a lifting module is arranged inside the coating chamber, a soft shaft passes through the coating chamber and drives the lifting module to move, the glue valve support plate is movably connected to the lifting module, the tension spring is retracted to limit the movement between the glue valve support plate and the lifting module, the limiting wheel is installed on the glue valve support plate and moves along the guide rail, the glue valve is fixed on the glue valve support plate, the glue mixing pipe is installed on the glue valve, the glue plate is connected to the glue valve support plate, the A / B component glue injection pipe and the air compressor pipe are both arranged on the top of the coating chamber, the vacuum suction cup is fixed to the coating chamber, and the gas-liquid mixing pump pipe is connected to the vacuum suction cup.

2. The underwater repair device for defects in the steel lining of a nuclear power plant water pool according to claim 1, characterized in that: Suspensions are additionally provided at other positions of the coating chamber.

3. The underwater repair device for defects in the steel lining of a nuclear power plant water pool according to claim 1, characterized in that: The repair gel is delivered to the glue coating valve through the A / B component glue injection pipe, and the compressed air is delivered to the coating chamber through the air compressor pipe to drain the water from the inside.

4. The underwater repair device for defects in the steel lining of a nuclear power plant water pool according to claim 1, characterized in that: The vacuum suction cup is fixed to the coating chamber via a vacuum suction cup connecting foot.

5. The underwater repair device for defects in the steel lining of a nuclear power plant water pool according to claim 1, characterized in that: The detachable cover is connected to the coating chamber to form a semi-sealed space, and the internal components can be easily replaced after removal.

6. The underwater repair device for defects in the steel lining of a nuclear power plant water pool according to claim 5, characterized in that: The sealing strip is installed at the window of the detachable cover.

7. The underwater repair device for defects in the steel lining of a nuclear power plant water pool according to claim 5, characterized in that: The one-way valve is fixed on the removable cover plate to drain water in one direction from inside to outside.

8. An underwater repair method for defects in the steel lining of a nuclear power plant pool, characterized in that: The steps include: Step 1: Use automatic or manual tools to make the A / B components flow out of the glue valve and mixing tube at a mass ratio of 1.5:

1. Wipe the resin gel at the tube mouth to complete the pre-filling. Step 2: Use a crane to connect the crane base to locate the coating chamber to the defect location of the spent fuel pool. The test bracket simulates the location of the spent fuel pool wall and bottom. Step 3: Start the gas-liquid mixing pump to evacuate the vacuum cup so that the coating cavity is adsorbed to the wall or bottom of the spent fuel pool; Step 4: Start the air compressor and inject compressed air into the coating chamber. After the water inside the coating chamber is discharged from the one-way valve at the bottom, stop injecting compressed air. Step 5: Turn the handwheel counterclockwise to drive the flexible shaft to move the lifting module to the bottom of the guide rail. Turn the handwheel clockwise to drive the flexible shaft to move the lifting module to the top of the guide rail. The glue valve support plate, glue valve, glue mixing tube, and glue plate also move upward at the same time to complete the glue coating at the defective position. Step 6: After the glue coating area completely covers the defective area, operate the controller to close the glue coating valve; Step 7: When the lifting module approaches the limit block, the limit wheel also approaches the limit block, and the glue valve support plate rotates counterclockwise to separate the glue mixing tube and glue coating plate from the working surface; Step 8: After waiting for an appropriate time, turn off the gas-liquid mixing pump and separate the vacuum suction cup from the pool wall or bottom; Step 9: Use a crane to connect the hanging seat to take the coating chamber out from underwater to complete the underwater gel coating work.

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