Construction method for adding sea water taking pump room in gate shaft structure of nuclear power station

Abstract

The invention belongs to the technical field of nuclear power station engineering construction, and particularly relates to a construction method for adding a sea water taking pump room in a nuclear power station gate shaft structure, which comprises the following steps of: 1, falling a gate after a nuclear power unit is overhauled and shut down, lowering the water level in a gate shaft below a working surface, and keeping the water level stable; 2, a steel platform is machined, and the machined steel platform is fixed in the gate shaft; 3, according to the hole opening point positions, drilling and cutting are conducted on the separation wall through the two stages of the daily window stage and the overhaul window stage, and holes are formed; 4, chiseling, drilling and hole cleaning are conducted on the holes, steel bars are planted in the holes, and the machined steel bars and the planted steel bars are bound and connected; 5, grouting is carried out after a fixed formwork is installed in the hole, the formwork is removed after grouting is completed, and anticorrosive paint is brushed after the surface of a grouting material is solidified and dried; and 6, the steel platform is dismantled. According to the method, the inter-pump water taking function can be achieved, the structural reliability can be met, and meanwhile the overhaul plan construction period of a power station is not affected.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power plant engineering construction, and in particular relates to a construction method for adding a seawater pump room in a gate well structure of a nuclear power plant. Background Art

[0002] The steam energy supply project requires a large amount of desalted water to be converted into steam output through heat exchange. The municipal water supply cannot meet the power station's demand for fresh water resources. It is necessary to extract seawater from the plant's circulating water system and convert it into desalted water through the desalination plant. The seawater in the third loop of the nuclear power plant is discharged into the sea through the gate well after heat exchange. Through space transformation, it can provide seawater sources for the power station's seawater desalination project.

[0003] During the operation of a nuclear power plant, the flow rate in the circulating water tunnel can reach 1.5 to 2 m / s. Underwater construction is not possible during the daily operation of the unit, and operations can only be carried out during the overhaul window of approximately 168 hours. The main problem is how to match the time for draining the gate well during the overhaul of the power plant, drill holes and cut walls at locations where scaffolding cannot be erected and there is no support on the gate well wall, connect the working area with the drainage area, and complete the reinforcement.

[0004] Therefore, how to use the unit overhaul window to complete the opening and reinforcement of the concrete wall below the tide line has become an urgent problem to be solved. Summary of the invention

[0005] The purpose of the present invention is to provide a construction method for adding a seawater intake pump room in a nuclear power plant gate well structure. The method is suitable for completing the opening and reinforcement of the concrete wall of the nuclear power plant gate well below the tide line by utilizing the unit overhaul window, which can not only realize the water intake function of the pump room, but also meet the structural reliability, and at the same time does not affect the planned construction period of the power plant overhaul.

[0006] The technical solution to achieve the purpose of the present invention is:

[0007] A construction method for adding a seawater pump room in a gate well structure of a nuclear power plant, the method comprising:

[0008] Step 1: After the nuclear power unit is shut down for overhaul, the gate is lowered, the water pump is lowered to the inside of the gate well, and the pump is started to pump water to reduce the water level in the gate well to below the working surface, and the water level is continuously stabilized;

[0009] Step 2, processing the steel platform, placing the processed steel platform into the gate well, and fixing it in the gate well;

[0010] Step 3: According to the opening points, drill and cut holes in the isolation wall during the daily window period and the overhaul window period to open up both sides of the isolation wall and form holes;

[0011] Step 4: Chisel, drill and clean the holes, then plant reinforcement in the holes. After planting reinforcement, tie and connect the processed reinforcement to the planted reinforcement.

[0012] Step 5: After installing a fixed template in the hole, grouting is carried out. After the grouting is completed, the template is removed, and the anti-corrosion paint is applied after the surface of the grouting material solidifies and dries;

[0013] Step 6: Remove the steel platform.

[0014] The steel platform frame is welded by I-beams and angle steels, and a steel grating plate is laid on the steel platform frame to form a working platform.

[0015] The steel platform is connected to the upper cross beam of the gate well through a steel wire rope, one end of the steel wire rope is connected to the steel wire rope fixing position of the upper cross beam of the gate well and is reinforced by a chemical bolt; the other end of the steel wire rope is connected to the steel wire rope fixing position of the steel platform; after the connection is completed, the length of the steel wire rope is ensured to be consistent.

[0016] The steel wire rope is provided with a length adjuster for adjusting the length of the steel wire rope.

[0017] The steel platform is connected and fixed to the inner surrounding beam of the gate shaft by expansion screws.

[0018] The step 3 is specifically as follows: during the daily window period, complete drilling of half the thickness of the isolation wall on the waterless side, and during the overhaul window period, complete the remaining drilling of the isolation wall and open up both sides of the isolation wall; according to the drilling position, straight line cutting is performed to separate the isolation wall to form holes, and the cut and separated hole concrete is hoisted out of the gate well.

[0019] In step 4, the diameter of the drilling drill bit is 4 to 8 mm larger than the diameter of the steel bar, and the drilling depth is not less than 470 mm.

[0020] When planting the reinforcement in step 4, the glue injection starts from the bottom of the hole and the glue injection in the hole reaches 1 / 3 of the hole depth.

[0021] The template is made of wooden template and square wood. After the template is made and fixed, stainless steel corner guards are embedded inside the template, and the outside of the template is fixed in the hole.

[0022] The anti-corrosion coating is a silane impregnated anti-corrosion coating.

[0023] The beneficial technical effects of the present invention are:

[0024] 1. The present invention provides a construction method for adding a seawater pump room in a nuclear power plant gate well structure. In a high-velocity seawater environment such as a circulating water gate well, the renovation of the water pump room is achieved by establishing an isolation area and a temporary working surface during a short construction window during unit overhaul.

[0025] 2. The present invention provides a construction method for adding a seawater pump room in a nuclear power plant gate shaft structure, which uses a temporary suspended steel platform to establish a gate shaft inner wall opening working surface, solving the problem that the base curvature is too large to set up scaffolding.

[0026] 3. The present invention provides a construction method for adding a seawater pump room in a nuclear power plant gate shaft structure, which utilizes the waterless side of the isolation wall to carry out partial structural construction in the pump room in advance, thereby reducing the total construction period required during the overhaul.

[0027] 4. The present invention provides a construction method for adding a seawater pump room in a nuclear power plant gate shaft structure, pre-drilling holes on the waterless side of the isolation wall, and reducing the time required to achieve drilling and penetration within the overhaul window.

[0028] 5. The present invention provides a construction method for adding a seawater pump room in a nuclear power plant gate shaft structure, using stainless steel corner guards and silane impregnation as protective materials to solve the anti-scouring and anti-corrosion problems of grouting materials immersed in seawater after construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is an elevation view of the opening position of the gate well provided by the present invention;

[0030] Figure 2 A top view of the temporary steel platform provided by the present invention;

[0031] Figure 3 This is an elevation view of the temporary steel platform provided by the present invention;

[0032] Figure 4 A schematic diagram of the drilling and cutting line positions provided by the present invention;

[0033] Figure 5 This is a schematic diagram of the stainless steel corner guard and silane impregnation anti-corrosion coating provided by the present invention.

[0034] In the figure: 1- newly added connecting hole; 2- expansion screw position; 3- wire rope position; 4- wire rope; 5- length adjuster; 6- steel platform; 7- water drill cutting line; 8- hole opening point; 9- angle steel. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0036] The present invention provides a construction method for adding a seawater pump room in a nuclear power plant gate well structure, which specifically includes the following steps:

[0037] Step 1: Lower the gate after stopping the reactor

[0038] After the nuclear power unit is shut down, the corresponding circulating water pump will be shut down within 48 hours. At this time, the circulating water corridor is at the same height as the tide level, and the relative flow rate is low, so the gate lowering work can be completed at low tide.

[0039] The gate well operation condition is located at -10m from the inner wall of the gate well. The pump room structure construction on the far water side can be carried out on a daily basis. During the overhaul period, the window of water level drop can be used to complete the remaining work on the near water side. For details, see Figure 1 .

[0040] Pump water to -10 meters: lower the pre-prepared water pump to the inside of the gate well, start pumping water, lower the water level in the gate well to below the working surface, and continuously stabilize the water level.

[0041] Step 2: Steel platform installation

[0042] Considering that the slope at the bottom of the gate shaft is too steep and not suitable for scaffolding, a suspended steel platform is used as the working platform.

[0043] Processing of steel platform 6: The steel platform frame is welded by I-beam and angle steel, on which a steel grating is laid to form an operating platform. The steel wire rope 4 is connected with the lifting lug to form a vertical force-bearing structure. The upper force-bearing point is located on the upper crossbeam of the gate well and is connected with chemical anchor bolts. The top view and elevation view of the steel platform 6 are as follows: Figure 2-3 shown.

[0044] Placement of the steel platform 6: First, determine the steel wire rope fixing position 3 on the upper cross beam of the gate well, connect one end of the steel wire rope 4 to the steel wire rope fixing position 3 of the upper cross beam of the gate well, and reinforce it with chemical bolts; then connect the other end of the steel wire rope 4 to the steel wire rope fixing position 3 of the steel platform 6. After the connection is completed, ensure that the length of the steel wire rope 4 is consistent. A length adjuster 5 is provided on the steel wire rope 4 to adjust the length of the steel wire rope 4. Preferably, the length adjuster 5 is located in the center of the steel wire rope 4 to ensure that the personnel can make fine adjustments to each steel wire rope 4 after going down to the steel platform 6. After the steel wire rope 4 is assembled with the upper cross beam of the gate well and the steel platform 6 as a whole, place the steel platform 6 in the gate well. Since the width of the steel platform exceeds the width of the concrete beam, vertical hoisting is adopted. After it is placed in place, the length adjuster 5 is used to ensure that the length of the steel wire rope is consistent and automatically maintains balance.

[0045] Personnel passage is connected: the downstairs passage adopts the original gate shaft ladder to the steel platform through the surrounding beam, and the fall arrester is used to ensure the safety of personnel. The scaffolder walks from the gate shaft maintenance ladder to the -1m platform, and on this basis, the -1m to -6m scaffolding ladder and guardrail are set up and reinforced, so that the drilling workers can safely reach the working steel platform.

[0046] Fixing of the steel platform 6: After the steel platform is placed, it is in a shaking state. Holes are drilled on the surrounding beams, and the steel platform 6 is connected and fixed to the surrounding beams by expansion screws 2, so that the entire steel platform 6 is in a stable and controllable state.

[0047] Step 3: Drill and cut the isolation wall to form holes

[0048] Water drilling: The isolation wall is 1m thick. The layout and positioning have been completed on the waterless side in the early stage, and the drilling point 8 has been determined. The daily window is used to complete the drilling depth of 0.5m. At this time, the drilling rig is directly arranged along the original drilling position to continue to complete the drilling work of the remaining concrete wall of the isolation wall and open up both sides of the isolation wall.

[0049] Wall cutting: After drilling, pass the traction rope through the concrete hole, and use an electric diamond wire saw to cut the blocks according to the water drill cutting line 7 formed by the traction rope; straight line cutting separates the original wall from the demolished part, and repairs or demolishes the holes that do not meet the requirements. According to the design drawings, cut the concrete blocks into square holes with a length and width that are 400mm larger than the design value, and each square hole is cut into 4 pieces. In order to facilitate the lateral discharge of the concrete blocks, the incision is larger on the outside and smaller on the inside, with a bevel. The block division method is as follows: Figure 4 shown.

[0050] After cutting, the concrete blocks are hoisted out: Each concrete block weighs 1.575 tons and is 1 meter thick. It is necessary to fix pulleys on the opposite side wall of the connecting hole 1, use a hoist and a crowbar to pull out the concrete blocks, and use a 25T truck crane to lift them outside the site. Before pulling them out completely, ensure that the connection with the truck crane is complete, and use the method of pulling and lifting to ensure that the concrete blocks are not placed on the steel platform.

[0051] Step 4: Roughen the inner wall of the hole, plant the steel bars, and tie the steel bars

[0052] Chiseling the inner wall of the hole and drilling the rebar hole: After the hole concrete is hoisted out, chisel the hole and drill the hole with an impact drill. When drilling, first use a rebar detector to check the distribution of the original rebar in the concrete, then use a line to locate the number and position of the rebar to be planted, mark the rebar position, and then use an impact drill to complete the drilling. The drill bit diameter should be about 4 to 8 mm larger than the rebar diameter, and the drilling depth should not be less than 470 mm;

[0053] Rebar planting on the inner wall of the hole: First clean the drilled holes for rebar planting to ensure that their cleanliness and moisture content meet the requirements before planting the rebar; start the injection of glue from the bottom of the hole to expel the air in the hole. In order to make the hole full of glue after the rebar is planted, but not to let the glue flow out, the injection of glue in the hole should reach 1 / 3 of the hole depth. Immediately after the injection of glue in the hole, the rebar should be planted; rebar planting should be carried out immediately after the injection of glue. First, inject the prepared structural glue into the hole, and apply the structural glue to the anchor end of the rebar 2-3mm, then slowly insert the rebar into the hole, and rotate the rebar at the same time to make the structural glue overflow from the empty mouth and expel the air in the hole; after the inspection and acceptance of the rebar planting, the pull-out test can be carried out only after the glue is completely solidified.

[0054] Rebar binding: According to the requirements of the drawings, the pre-processed steel bars are bound and connected with the embedded bars.

[0055] Step 5: Grouting the inner wall of the hole and applying anti-corrosion paint

[0056] Formwork assembly: Assemble embedded parts and formwork according to the requirements of the drawings, use 1830*915*13mm wooden formwork and 40*90mm square wood for production and installation, embed stainless steel corner guards 9 after the wooden frame is fixed, and fix them on the wooden frame with nails; the outer formwork is directly fixed to the concrete wall with steel nails, and screws are used for reinforcement after the fixing is completed. The inner side is reinforced with wooden squares. Figure 5 shown.

[0057] Grouting: Clean the area to be grouted. The surface of the equipment foundation should be fully moistened before grouting, and the accumulated water should be removed. Control the water-cement ratio according to the product manual, use mechanical stirring, and the stirring time is generally 1 to 2 minutes. It is strictly forbidden to add any admixtures.

[0058] Formwork removal: The formwork should be removed 24 hours after grouting is completed.

[0059] Anti-corrosion coating: After the surface of the grouting material solidifies and dries, apply the silane impregnation anti-corrosion layer by brushing. Use the roller coating method and apply it twice. When painting, brush out the joint point for more than 20cm. According to the product manual, the two coats of anti-corrosion coating must be applied at least 2 hours apart.

[0060] Step 6: Steel platform removal

[0061] After all the preliminary work is completed, the expansion screws 2 connecting the steel platform and the surrounding beam are removed, and the lifting operation is carried out after the personnel evacuate the steel platform.

[0062] The time taken for each step of the above work is as follows:

[0063] After the reactor is shut down, the gate is lowered → water is pumped to -10 meters (10 hours) → the steel platform is placed (4 hours) → the personnel passage is connected (6 hours) → the steel platform is fixed (2 hours) → holes are drilled with a water drill (8 hours) → wall cutting (12 hours) → concrete blocks are hoisted out after cutting (12 hours) → the inner wall of the hole is roughened and holes for embedding reinforcement are drilled (30 hours) → reinforcement is embedded in the inner wall of the hole (24 hours) → reinforcement is tied (8 hours) → stainless steel corner guards are installed and formwork is supported (8 hours) → grouting and maintenance (30 hours) → formwork is removed (4 hours) → anti-corrosion paint is applied (6 hours) → steel platform is removed and hoisted (4 hours).

[0064] The total time taken was 168 hours, and the work plan was arranged in two shifts of 24 hours.

[0065] The present invention is described in detail above with reference to the accompanying drawings and embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. The contents not described in detail in the present invention can adopt the existing technology.

Claims

1. A construction method for adding a seawater pump room in a nuclear power plant gate well structure, characterized in that: The method comprises: Step 1: After the nuclear power unit is shut down for overhaul, the gate is lowered, the water pump is lowered to the inside of the gate well, and the pump is started to pump water to reduce the water level in the gate well to below the working surface, and the water level is continuously stabilized; Step 2, processing the steel platform (6), placing the processed steel platform (6) into the gate well, and fixing it in the gate well; Step 3: according to the opening point (8), drilling and cutting are performed on the isolation wall during the daily window period and the overhaul window period to open up both sides of the isolation wall and form holes; Step 4: Chisel, drill and clean the holes, then plant reinforcement in the holes. After planting reinforcement, tie and connect the processed reinforcement to the planted reinforcement. Step 5: After installing a fixed template in the hole, grouting is carried out. After the grouting is completed, the template is removed, and the anti-corrosion paint is applied after the surface of the grouting material solidifies and dries; Step 6: Remove the steel platform.

2. A construction method for adding a seawater pump room in a nuclear power plant gate shaft structure according to claim 1, characterized in that: The steel platform (6) frame is welded from I-beams and angle steels, and a steel grating plate is laid on the steel platform frame to form a working platform.

3. The construction method for adding a seawater pump room in a gate well structure of a nuclear power plant according to claim 1, characterized in that: The steel platform (6) is connected to the upper cross beam of the gate well through a steel wire rope (4), one end of the steel wire rope (4) is connected to the steel wire rope fixing position (3) of the upper cross beam of the gate well, and is reinforced by chemical bolts; The other end of the steel wire rope (4) is connected to the steel wire rope fixing position (3) of the steel platform (6); after the connection is completed, the length of the steel wire rope (4) is ensured to be consistent.

4. A construction method for adding a seawater pump room in a gate well structure of a nuclear power plant according to claim 3, characterized in that: The steel wire rope (4) is provided with a length adjuster (5) for adjusting the length of the steel wire rope (4).

5. The construction method for adding a seawater pump room in a nuclear power plant gate shaft structure according to claim 1, characterized in that: The steel platform (6) is connected and fixed to the inner perimeter beam of the gate shaft via expansion screws (2).

6. The construction method for adding a seawater pump room in a gate well structure of a nuclear power plant according to claim 1, characterized in that: The step 3 is specifically as follows: during the daily window period, complete drilling of half the thickness of the isolation wall on the waterless side, and during the overhaul window period, complete the remaining drilling of the isolation wall and open up both sides of the isolation wall; according to the drilling position, straight line cutting is performed to separate the isolation wall to form holes, and the cut and separated hole concrete is hoisted out of the gate well.

7. The construction method for adding a seawater pump room in a gate well structure of a nuclear power plant according to claim 1, characterized in that: In step 4, the diameter of the drilling drill bit is 4 to 8 mm larger than the diameter of the steel bar, and the drilling depth is not less than 470 mm.

8. The construction method for adding a seawater pump room in a gate well structure of a nuclear power plant according to claim 1, characterized in that: When planting the reinforcement in step 4, the glue injection starts from the bottom of the hole and the glue injection in the hole reaches 1 / 3 of the hole depth.

9. The construction method for adding a seawater pump room in a gate well structure of a nuclear power plant according to claim 1, characterized in that: The template is made of wooden template and square wood. After the template is made and fixed, a stainless steel corner guard (9) is fixedly embedded inside the template, and the outside of the template is fixed in the hole.

10. The construction method for adding a seawater pump room in a gate shaft structure of a nuclear power plant according to claim 1, characterized in that: The anti-corrosion coating is a silane impregnated anti-corrosion coating.

Images