Method for manufacturing, mounting and sealing test of spent fuel pool steel covering surface

Abstract

The invention belongs to a test method, and particularly relates to a spent fuel pool steel covering surface manufacturing, mounting and sealing test method. The method comprises the following steps of prefabrication of a stainless steel plate, installation of expansion bolts, installation of a gusset plate or a supporting plate, installation of a keel, secondary plastering of a keel area, installation of a door frame, installation of a covering plate, pickling passivation and water seal testing, and the installation test activity is completed. The method has the remarkable effect that reliable and powerful guarantee is provided for follow-up supporting plate installation, gusset plate installation and keel installation. Aiming at the installation of the door frame, the problems of narrow space and incapability of normal hoisting and installation are solved. And aiming at the installation of the covering plate, all covering surfaces are smoothly hoisted in place and welded, and the qualification of a welding seam is ensured through a nondestructive testing mode, so that the sealing performance of the welding seam of the pool is ensured. Deionized water is used for carrying out a water storage test on the pool, the sealing performance of a weld joint of the pool is reflected more visually, and a guarantee and a foundation are provided for installation of other items of the pool if the water sealing test is qualified.

Description

Technical Field

[0001] The invention belongs to a test method, and in particular relates to a spent fuel pool steel cladding manufacturing, installation and sealing test method. Background Art

[0002] The spent fuel stainless steel pool of the spent fuel reprocessing industrial demonstration plant is mainly used to receive and store spent fuel assemblies retired after combustion in nuclear power plant reactors. After being stored in the stainless steel pool filled with boron water for a certain period of time, the retired spent fuel assemblies are transported in water to subsequent plants for processing using fuel gripper assemblies. At present, retired fuel assemblies in nuclear power plants in my country are temporarily stored in spent fuel pools of nuclear power plants. Due to the accumulation of time, the spent fuel pools of nuclear power plants are close to their storage capacity, and the current storage capacity problem needs to be solved urgently. Therefore, the construction of a spent fuel reprocessing plant is an important task to solve the storage of spent fuel assemblies, and the construction of a stainless steel pool for storing spent fuel assemblies is the most basic step.

[0003] The defects of the existing technology are that it is difficult to ensure the quality and quantity of the stainless steel covering of the pool, complete the installation work safely and effectively in a limited space, ensure the overall size and installation accuracy of the pool, and ensure that the stainless steel pool does not leak during the entire production and operation period. Summary of the invention

[0004] Aiming at the defects of the prior art, the present invention provides a method for manufacturing, installing and sealing a steel covering of a spent fuel pool.

[0005] The present invention is implemented as follows: a method for manufacturing, installing and sealing a spent fuel pool steel covering, which includes the following steps: prefabrication of stainless steel plates → installation of expansion bolts → installation of node plates or support plates → installation of keels → secondary plastering of keel areas → installation of door frames → installation of covering panels → pickling and passivation → water sealing test, and the installation and test activities are completed.

[0006] The above-mentioned method for manufacturing, installing and sealing the steel covering of a spent fuel pool comprises the following steps:

[0007] Step S1, the prefabrication of the stainless steel plate mainly includes the prefabrication of the keel support plate, the prefabrication of the node plate, the prefabrication of the keel, the prefabrication of the covering plate, and the prefabrication of the blocking cover plate. In the prefabrication process of each steel component, it is strictly carried out in accordance with the cutting drawing, and the identification and numbering, and the protection of semi-finished products and finished products are done well in the process. In particular, in the process of making the keel, the stainless steel plate must first be cut into strips, and then bent by a bending machine. The bending has high precision and great difficulty. After bending, correction processing is required. After correction, the upper and lower bent plates of the keel need to be assembled and welded. After welding, the keel needs to be corrected again.

[0008] The prefabrication of the keel support plate includes cutting, drilling and punching;

[0009] The prefabrication of the keel includes cutting, bending, welding, correction and assembly.

[0010] Step S2, before the installation of the expansion bolts, the spent fuel pool needs to be laid out. The center line of each keel should be laid out on the primary concrete wall in strict accordance with the dimensions specified in the drawings and the center position of the node plate should be determined. After the center position is determined, the positions of the node plate expansion bolts and the support plate expansion bolts are confirmed on both sides of the center position. It should be noted that the distance between the two bolts in the vertical direction of the wall is less than or equal to 400, and the distance between the ground bolts is less than or equal to 330. Mark according to the maximum value. After the position is confirmed, use an electric drill to drill holes at the marked positions. The drilling depth must not be less than 50mm. After drilling on site, the holes must be purged with a vacuum cleaner or cleaned with high-pressure water. Under no circumstances are foreign matter allowed to remain in the holes. After the hole is cleaned, the expansion bolt screw is installed. When installing the expansion bolt screw, a plumb line is hung at the highest point of the wall to make the installed screw end flush with the plumb line. Finally, after all the screws are driven into the bolt holes, a nut is screwed in and tightened. The torque wrench is used to tighten it to its torque value, and then a second nut is hung on the screw as an adjustment nut.

[0011] Step S3, the installation of the node plate is to pass the prefabricated 300*300*6 node plate bottom plate with 4 holes through the bolt holes and place it above the adjusting nut, and then fix the node plate bottom plate with the third nut, and fix the node plate bottom plate with the adjusting nut and the last installed nut after measuring the spatial distance and flatness. After the node plate bottom plate is installed, the prefabricated keel support plate with 2 long holes of 340*80*12 is horizontally inserted into the installed screw rods, and then the support plate is fixed with the third fastening nut. Before the support plate is fixed, the support plate needs to be adjusted to the same plane so that its plane is flush with the surface of the node plate bottom plate, and the support plate is adjusted to the same plane using the adjusting nut and the fixing nut.

[0012] Step S4, the keel installation transports the keels that have been prefabricated in the workshop according to the numbers, and transports them from the workshop to the site for temporary storage according to the numbers required for on-site installation. Then, they are lifted to the installation position one by one by a gantry crane with a lifting belt. After being lifted to the installation position, the keel is adjusted and installed, and the connection between the keel and the support plate is spot welded and fixed. Then, the hook is removed, and the keel installation at other positions is performed in the same way. When installing the ground keel, the ground leak detection pipe needs to be laid in advance according to the requirements of the drawing, and installed together with the keel. After the keel is spot welded and fixed, it can be installed. Weld the connection between the keel and the support plate. After welding, check again whether the flatness of the keel and the spacing between the two parallel planes meet the requirements. If the flatness and the spacing between the two parallel planes do not meet the requirements, adjust the nuts and tighten the nuts to meet the installation accuracy requirements. When adjusting the ground keel, the elevation needs to be re-measured. By selecting the elevation of each point for re-measurement, adjusting the nuts and tightening the nuts, the flatness of the keel is within the required range. Finally, check the torque of the tightening nuts again. After the inspection is qualified, the nuts are spot welded.

[0013] Step S5, before the secondary plastering of the keel area, the keel needs to be protected to prevent the mortar from contaminating the keel or the mortar from flowing into the keel and blocking the leak detection pipe during the plastering process; the plastering angle steel should be installed at each corner according to the drawing, so that the edge covering panel can be installed smoothly when the corner is installed after plastering. Before plastering the wall, the concrete surface should be rough. On the first day, the wall should be cleaned and soaked with water until it is saturated with water. On the second day, a 5mm thick bonding layer is applied on the soaked pool wall with mortar mixed with admixtures; on the third day, after the bonding layer is completed, the middle layer is plastered. The plastering thickness of each layer of the middle layer is 15-20mm, and the interval is 4-5 hours. If there are three layers, the third layer should not be plastered on the same day; the surface layer should be plastered and polished on the second day after the middle layer is completed. The minimum thickness of the surface layer is 10mm. The bottom of the pool is plastered with mortar mixed with admixtures. The surface of the plaster layer should be smooth. After plastering, remove the finished product protective covering film, clean the outer surface of all stainless steel to prevent it from carrying residues such as cement slurry, and there should be no gaps between the plaster layer and the base surface and steel. The surface of the final surface layer should be smooth and flat, and the plastering flatness should meet ±2mm. Use a new aluminum alloy square ruler to check, and there should be no cracks and bumps on the plastered surface. After all inspections are qualified, apply dust-proof paint to the wall and pool bottom plaster surface.

[0014] Step S6, the installation of the door frame is to slowly lift the prefabricated door frame to the transport vehicle after it has passed the inspection in the workshop, and tie and fix the door frame. The specifications of the door frame are 8514mm long, 2670mm wide, and 1500mm high. The width between the U-shaped openings in the width direction of the door frame is 1m, and the weight of the door frame is 3.2T. The transport vehicle is slowly transported into the factory and moved to the area where the on-site gantry crane can lift it. The door frame is temporarily lifted to the ground by the gantry crane for storage. Due to the small space and the limited height of the gantry crane, special attention should be paid to the surrounding fences. The gantry crane trolley is driven above the door frame, and the lifting lugs are connected. The upper part of the door frame is connected with an electric hoist, and the bottom is connected with a crane trolley hook. Then the door frame is slowly lifted for trial lifting. After observing that there are no abnormalities with the crane, lifting belt and fall chain, two slip ropes are fastened at the bottom of the door frame to control the door frame during the lifting and flipping process. In order to prevent large swings or slips during the flipping process, a round hole at the bottom of the door frame is set. Use a lifting belt and a fall chain to control the door frame during the flipping process, ensuring the length is 10m. After lifting the door frame 3m, move the trolley to the door frame position and the door frame begins to flip. First, slowly lift the electric fall chain on the top of the door frame, and keep the trolley hook still. Slowly move the trolley to the outside according to the flipping progress. Carefully observe the lifting process. The chain at the bottom of the door frame should also change as the door frame flips gradually. During the whole process, the electric fall chain should be parallel to the trolley hook, and each should be in a vertical state. Slowly move the crane to verify the position, and then slowly use the electric fall chain to Lower the door frame and strictly monitor the entire lowering process. After it is lowered to the specified position, adjust the door frame appropriately, spot weld the cladding on the side of the door frame to the steel section, place two 20# I-beams on the top of the door frame, connect the door frame and the I-beams with slings, add fall chains for adjustment when necessary, then remove the crane, and finally adjust the door frame to the position, butt weld the cladding on the door frame and the wall cladding to the steel section, seal the gap between the wall and the steel cladding in the secondary casting area of ​​the door frame with sealant, and pour the secondary casting area of ​​the door frame after the sealing is completed.

[0015] Step S7, before installing the cladding panels, the prefabricated cladding panels should be numbered according to the drawing numbers according to the site requirements, transported from the workshop to the construction site by a flatbed truck, temporarily stored on the ground, and hoisted and put into place in sequence from top to bottom by a crane connected to the lifting belt and shackle and the cladding panel hoisting tooling, and then spot welded to the keel after adjustment. When assembling the cladding panels, strictly follow the gap requirement of 2 to 4 mm. When spot welding, first spot weld and fix them, first spot weld the edge of the field and then spot weld the short side, and the spot welding spacing is 200 mm. If welding is not done in time after electric welding, protective measures should be taken for the weld with paper tape, and before welding the main weld of the steel cladding, The cladding panels shall be subjected to top pressure. When welding, the short ones shall be welded first and the long ones later, the horizontal ones shall be welded first and the vertical ones later, the welding shall be conducted in sections, the welding shall be conducted symmetrically and the welding shall be conducted simultaneously. When welding in sections, the temperature of the interlayers shall be controlled below 150℃ with an interval of 300mm after welding every 400mm before welding the next layer. Note that before the bottom plate cladding panels are put in place, the keels, the ground and the leak detection tubes shall be checked for foreign matter before the cladding panels are installed. After the main welds of the cladding panels are welded, the welds shall be subjected to visual inspection, vacuum box inspection, liquid penetration inspection and radiographic inspection. After the main welds are inspected and qualified, the node plate cover shall be plugged. After plugging, the welds shall be subjected to visual inspection, vacuum box inspection and liquid penetration inspection and qualified.

[0016] Step S8, the water pool needs to be cleaned before the pickling and passivation of the steel cladding weld. After cleaning, the pickling and passivation paste is applied to the water pool weld, the heat-affected zone around the weld, and the contaminated cladding with a thickness of 1 to 2 mm, and maintained for 0.5 to 1 hour. The applied pickling and passivation paste is wiped off with a white cotton cloth moistened with deionized water, and the passivated surface is sprayed and washed with a high-pressure water gun until the pH value no longer changes. No corrosion points are allowed to form within at least 24 hours after pickling and passivation. If rust spots appear on the surface, the surface of all areas where the rust spots appear needs to be pickled and passivated again. The wastewater generated by pickling should be collected in the specified area for unified treatment.

[0017] Step S9, before the water seal test of the water pool, all steel cladding welds are inspected and qualified, the underwater sealing door has been installed, the electrical control cabinet has been debugged, the deionized water pipeline has been connected, deionized water is available, all scaffolding in the water pool has been removed, and a temporary water receiving trough is made on the waterless side of the sealing door. After filling with water, collect the water leaking from the sealing door and collect it all in the water receiving trough. After everything is ready, open the valve and start filling with water. The filling process should be closely monitored. After the water is filled to the water pool -0.5m to reach the design elevation, it should be maintained for at least 15 days. During the full water test, the leakage of the sealing door on the waterless side does not exceed 2L per hour, which is qualified, and no water flows out of the leak detection pipe in the leak detection room, which is qualified, indicating that all the sealing welds of the water pool are qualified.

[0018] In the above-mentioned method for manufacturing, installing and sealing a spent fuel pool steel cladding, in step S1, prefabricated steel components are used to ensure the construction period of the construction site.

[0019] A method for manufacturing, installing and sealing a spent fuel pool steel cladding as described above, wherein, in step S2, after laying out the wall surface according to the drawing requirements to determine the position of the expansion bolts, drilling is performed to ensure that the holes are perpendicular to the wall surface, and after the drilling is completed and the holes are cleaned, the expansion bolts are installed, and the outer ends of the expansion bolt screws are placed on the same plane, and after the expansion bolt screws are installed, the first nut is screwed in to tighten them to their torque value, and the second adjustment nut is screwed into the expansion bolt screw again, and the correct installation of the expansion bolts ensures the installation progress of the node plate base plate and the support plate, and also ensures the overall installation accuracy.

[0020] According to the method for manufacturing, installing and sealing the steel cladding of a spent fuel pool, in step S3, the node plate bottom plate and the support plate are inserted into the adjustment nuts of the installed expansion bolts, and then the third fastening nut of the expansion bolt is inserted into the screw rod, and the node plate bottom plate and the support plate are adjusted to the same plane by using the adjusting screw eye and the fastening nut, so that the node plate bottom plate and the support plate on the entire surface are on the same plane, thereby ensuring the installation accuracy and progress of the keel.

[0021] A method for manufacturing, installing and sealing a spent fuel pool steel cladding as described above, wherein, in step S4, corresponding keels are installed on the installed node plate bottom plate and the support plate, and the keels are fixed to the support plate by welding. After the keels are welded to the node plate bottom plate and the support plate, all keels are adjusted to the same plane by adjusting nuts and fastening nuts. When installing the bottom plate keel, the leak detection tube needs to be installed under the keel in advance. After the keel installation is completed and accepted, the fastening nuts are spot welded and fixed. The installation of the entire keel lays a foundation for the installation of the steel cladding panel, ensuring the overall size and flatness of the steel cladding.

[0022] In the method for manufacturing, installing and sealing the steel cladding of a spent fuel pool as described above, in step S5, the installed keel area is subjected to secondary plastering. After three layers of plastering, the plastering area between the two keels is checked for flatness using a square ruler. The flatness does not exceed 2 mm. After the inspection is qualified, the plastering surface layer is painted. In order to prevent the mortar from falling off during the construction process and affecting the flaw detection results of the main weld and the leak detection system, the finished product protection and inspection work must be done well. This work ensures the overall dimensional accuracy of the steel cladding and the qualified rate of the main weld.

[0023] In the method for manufacturing, installing and sealing the steel cladding of a spent fuel pool as described above, in step S6, an electric fall chain and a lifting belt are hung on the gantry crane, and then the fall chain and the lifting belt are connected by the hook of the gantry crane trolley to lift, flip and put the door frame into position. This method not only solves the problem of difficult installation, but also solves the shortcomings of narrow space and insufficient lifting height, ensures that a large-sized heterogeneous door frame is successfully lifted and put into position at one time, achieves the installation accuracy of the steel cladding, and also ensures the overall installation accuracy of the steel cladding and the installation of the sealed door.

[0024] A method for manufacturing, installing and sealing a spent fuel pool steel cladding as described above, wherein, in step S7, a steel cladding hoisting tool is used to safely hoist the cladding panel to the installation position, especially the hoisting of some cladding panels with a longer length into place, and the entire process is carefully deployed and strictly constructed, ultimately ensuring the installation progress of the cladding panel. During the welding process, by strictly following the welding measures, welding sequence, and setting top pressure, the weld flaw detection pass rate is greatly improved, and the weld welding quality is improved.

[0025] The above-mentioned method for manufacturing, installing and sealing the steel cladding of a spent fuel pool, wherein in step S8, pickling and passivating the weld using a pickling and passivation paste effectively solves the problem of using concentrated sulfuric acid and concentrated nitric acid, greatly reduces the occurrence of safety incidents / accidents, and also improves the efficiency of pickling and passivation.

[0026] In step S9, a water pool water sealing test is used to verify the sealing of the water pool welds and the sealing door. The long-term water storage test can effectively verify the leakage defects of the water pool welds, ensure the sealing of the water pool and its safety in later use, and also provide protection for the installation of other equipment and lay the foundation.

[0027] The remarkable effect of the present invention is that through the effective control of the installation accuracy of the expansion bolts of the water pool, a reliable and strong guarantee is provided for the subsequent installation of the support plate, the node plate and the keel. For the installation of the door frame, the problem of small space and inability to lift and install normally is solved, and finally the door frame is safely and effectively put in place while ensuring quality and quantity. For the installation of the covering panel, the difficulties are also overcome, and an unconventional installation method is adopted. All the coverings are smoothly lifted and welded in place, and the welds are qualified through non-destructive testing methods to ensure the sealing of the water pool welds. The water storage test of the water pool using deionized water more intuitively reflects the sealing of the water pool welds. The qualified water sealing test also provides a guarantee and basis for the installation of other items in the water pool, and also creates conditions for the storage of spent fuel assemblies. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1a Stereoscopic drawing of keel prefabrication;

[0029] Figure 1b yes Figure 1a The main view;

[0030] Figure 2 Installation of expansion bolts;

[0031] Figure 3 Installation of gusset plate;

[0032] Figure 4a Installation drawing of keel support plate and keel;

[0033] Figure 4b yes Figure 4a A top view of

[0034] Figure 5a Installation drawing of node plate plugging plate (one-way node);

[0035] Figure 5b Installation drawing of node plate plugging plate (two-way node);

[0036] Figure 5c Installation drawing of node plate plugging plate (two-way node, another form);

[0037] Figure 5d Installation drawing of node plate plugging plate (tee node);

[0038] Figure 5e Installation drawing of node plate plugging plate (four-way node);

[0039] Figure 6a Installation drawing of square hole cover plate of node plate (one-way node);

[0040] Figure 6b Installation drawing of square hole cover plate of node plate (two-way node);

[0041] Figure 6c Installation drawing of square hole cover plate of node plate (two-way node, another form);

[0042] Figure 6d Installation drawing of square hole cover plate of node plate (tee node);

[0043] Figure 6e Installation drawing of square hole cover plate of node plate (four-way node);

[0044] Figure 7a Secondary plastering and painting of the keel area;

[0045] Figure 7b yes Figure 7a A top view of

[0046] Figure 8 Door frame hanging diagram;

[0047] Fig. 9 The door frame is poured for the second time after it is in place;

[0048] Fig.10 Installation details of steel cladding panels;

[0049] Fig.11 Water tightness test flow chart.

[0050] In the figure: 1. keel, 2. expansion bolt, 3. concrete wall, 4. node plate bottom plate, 6. keel support plate, 5. reinforcement plate, 7. blocking plate, 8. square hole plate, 9. plaster surface, 10. door frame, 11. gantry crane trolley, 12. electric fall chain, 13. lifting belt, 14. door frame secondary pouring area, 15. covering plate, 16. blocking plate, 17. covering weld, 18. leak detection tube, 19. trial mirror, 20. leak detection tank, 1-1. upper curved plate, 1-2. lower curved plate, 2-1. screw, 2-2. nut, 2-3. adjustment nut, 2-4. fastening nut. DETAILED DESCRIPTION

[0051] The method for manufacturing, installing and sealing the spent fuel pool steel cladding described in the present invention is described in detail with reference to Figures 1-10.

[0052] like Figure 1a and 1b As shown, the prefabrication of the keel 1 is to cut the stainless steel plate according to the size of the upper curved plate 1-1 and the lower curved plate 1-2 of the keel after unfolding, and then bend the cut material on a bending machine, and the finished products after bending are the upper curved plate 1-1 and the lower curved plate 1-2. After the upper and lower curved plates are corrected, the upper curved plate 1-1 and the lower curved plate 1-2 are assembled together by intermittent welding to form the keel 1. If the keel is deformed after assembly, the keel should be corrected by using a piano key type or other form of tooling.

[0053] like Figure 2 As shown, the installation position of the expansion bolt 2 for fixing the node plate bottom plate and the support plate is released by using the center line of the keel, and a hole is drilled on the primary concrete wall 3. Then, the drilled hole is cleaned and the screw 2-1 of the expansion bolt 2 is installed. After the screw is installed to the required depth, the nut 2-2 is tightened and screwed to the design required torque value, and then the second nut 2-3 is screwed into the screw 2-1.

[0054] like Figure 3As shown in 4 (4a-4b), the node plate bottom plate 4 and the keel support plate 6 are installed according to the installed expansion bolts 2. Before installing the node plate bottom plate 4 and the keel support plate 6, the adjusting nut 2-3 is adjusted according to the theoretical size of the covering surface, and then the node plate bottom plate 4 and the keel support plate 6 are installed, and the nut 2-4 is screwed into the screw 2-1 of the expansion fastening bolt 2. After the node plate bottom plate 4 is installed according to the theoretical size, the fastening nut 2-4 is screwed to its design torque value, and then the center plane of the keel support plate is adjusted to be on the same plane as the surface of the node plate bottom plate. According to the requirements of the drawing, the reinforcing plate 5 is welded above the node plate bottom plate 4. The keel 1 is lifted to the position of the keel support plate by the gantry crane, and the operator places the keel on the support plate 6 so that the two ends of the keel overlap 45mm on the support plate bottom plate 4. After the bottom surface of the lower curved plate 1-2 is fitted with the upper surface of the support plate, the keel is welded to the support plate and the node plate bottom plate. (When installing the bottom plate keel, the leak detection tube must be installed first, and then the keel can be installed after the leak detection tube is installed.) After welding is completed, the verticality and flatness of the keel 1 are adjusted again using the adjustment nut 2-3 and the fastening nut 2-4. After the entire plane of the keel meets the requirements, the fastening nut 2-4 is spot welded and the screw that is higher than the keel is cut off.

[0055] As shown in Figures 5 (5a-5e) and 6 (6a-6e), the types of node plates include one-way node, two-way node, three-way node, and four-way node. After the above node plate bottom plate and the keel are installed, a blocking plate 7 needs to be welded to other parts of the node plate bottom plate and the keel edge, and then the installed node plate is covered with a square hole plate 8, the edge of the square hole plate 8 is butt-welded to the keel edge, and the edge without the keel is welded to the blocking plate.

[0056] As shown in FIG. 7 (7a-7b), after the node plate and the keel are installed, the area below the keel surface is filled with mortar by secondary plastering, and the plastering surface 9 is flush with the keel surface. Then, the secondary plastering surface is painted with dust-proof paint, but mortar and paint contamination are not allowed in the keel and the node plate.

[0057] like Figure 8 , 9 As shown, the door frame 10 is transported to the site and hoisted to a temporary storage position by a gantry crane. The electric fall chain 12 and the lifting belt 13 are tied above the top of the gantry crane by calculation. The door frame is hoisted by connecting the fall chain and the lifting belt with the hook of the gantry crane trolley 11. The door frame installation position is checked before hoisting. After the check is correct, the door frame is hoisted to its installation position by a gantry crane. After it is in place, it is adjusted. After the position adjustment is qualified, the door frame perimeter cover is welded and fixed to the keel. Then the part of the door frame that contacts the wall is sealed with sealant. After sealing, the secondary pouring area 14 of the door frame is poured in layers.

[0058] like Fig.10As shown, the cladding panels 15 that have been laid are hoisted to their installation positions by a gantry crane, and the sides of the cladding panels are parallel to the center of the keel, and the gap between the cladding panels is 2 to 4 mm. The cladding panels are first spot welded and fixed, and then the welds are welded, and finally the welds are subjected to non-destructive testing. After the non-destructive testing is qualified, the square holes at the node plates are blocked with plugging plates 16. After the blocking is completed, the welds are subjected to non-destructive testing and qualified. Finally, all welds in the pool are pickled and passivated.

[0059] like Fig.11 As shown, before the water sealing test of the water pool, check that the sealing door has been installed, and the water pool is filled with water after the air source, control box and water source meet the requirements. After the water pool is filled with water, it is left to stand for 15 days. During the standing period, the leak detection tube is used to verify whether the water pool cover weld 17 is defective. If there is a defect, water flows from the cover weld 17 to the keel 1, and then flows into the leak detection tube 18, through the test mirror 19 connected to the leak detection tube, and finally flows to the leak detection tank 20 in the leak detection room. During the entire leak detection process, the sealing of the water pool is determined by checking whether there is water in the test mirror 19 and the leak detection tank 20 in the leak detection room. If no water droplets are formed, it means that the water pool weld is not defective, and the water sealing test is qualified.

Claims

1. A method for manufacturing, installing and sealing a spent fuel pool steel cladding, characterized in that: The installation test activities are completed by including the following steps: prefabrication of stainless steel plates → installation of expansion bolts → installation of node plates or support plates → installation of keels → secondary plastering of keel areas → installation of door frames → installation of covering panels → pickling and passivation → water sealing test.

2. A method for manufacturing, installing and sealing a spent fuel pool steel cladding as claimed in claim 1, characterized in that: The following steps are included: Step S1, the prefabrication of the stainless steel plate mainly includes the prefabrication of the keel support plate, the prefabrication of the node plate, the prefabrication of the keel, the prefabrication of the covering plate, and the prefabrication of the blocking cover plate. In the prefabrication process of each steel component, it is strictly carried out in accordance with the cutting drawing, and the identification and numbering, and the protection of semi-finished products and finished products are done well in the process. In particular, in the process of making the keel, the stainless steel plate must first be cut into strips, and then bent by a bending machine. The bending has high precision and great difficulty. After bending, correction processing is required. After correction, the upper and lower bent plates of the keel need to be assembled and welded. After welding, the keel needs to be corrected again. The prefabrication of the keel support plate includes cutting, drilling and punching; The prefabrication of the keel includes cutting, bending, welding, correction and assembly. Step S2, before the installation of the expansion bolts, the spent fuel pool needs to be laid out. The center line of each keel should be laid out on the primary concrete wall in strict accordance with the dimensions specified in the drawings and the center position of the node plate should be determined. After the center position is determined, the positions of the node plate expansion bolts and the support plate expansion bolts are confirmed on both sides of the center position. It should be noted that the distance between the two bolts in the vertical direction of the wall is less than or equal to 400, and the distance between the ground bolts is less than or equal to 330. Mark according to the maximum value. After the position is confirmed, use an electric drill to drill holes at the marked positions. The drilling depth must not be less than 50mm. After drilling on site, the holes must be purged with a vacuum cleaner or cleaned with high-pressure water. Under no circumstances are foreign matter allowed to remain in the holes. After the hole is cleaned, the expansion bolt screw is installed. When installing the expansion bolt screw, a plumb line is hung at the highest point of the wall to make the installed screw end flush with the plumb line. Finally, after all the screws are driven into the bolt holes, a nut is screwed in and tightened. The torque wrench is used to tighten it to its torque value, and then a second nut is hung on the screw as an adjustment nut. Step S3, the installation of the node plate is to pass the prefabricated 300*300*6 node plate bottom plate with 4 holes through the bolt holes and place it above the adjusting nut, and then fix the node plate bottom plate with the third nut, and fix the node plate bottom plate with the adjusting nut and the last installed nut after measuring the spatial distance and flatness. After the node plate bottom plate is installed, the prefabricated keel support plate with 2 long holes of 340*80*12 is horizontally inserted into the installed screw rods, and then the support plate is fixed with the third fastening nut. Before the support plate is fixed, the support plate needs to be adjusted to the same plane so that its plane is flush with the surface of the node plate bottom plate, and the support plate is adjusted to the same plane using the adjusting nut and the fixing nut. Step S4, the keel installation transports the keels that have been prefabricated in the workshop according to the numbers, and transports them from the workshop to the site for temporary storage according to the numbers required for on-site installation. Then, they are lifted to the installation position one by one by a gantry crane with a lifting belt. After being lifted to the installation position, the keel is adjusted and installed, and the connection between the keel and the support plate is spot welded and fixed. Then, the hook is removed, and the keel installation at other positions is performed in the same way. When installing the ground keel, the ground leak detection pipe needs to be laid in advance according to the requirements of the drawing, and installed together with the keel. After the keel is spot welded and fixed, it can be installed. Weld the connection between the keel and the support plate. After welding, check again whether the flatness of the keel and the spacing between the two parallel planes meet the requirements. If the flatness and the spacing between the two parallel planes do not meet the requirements, adjust the nuts and tighten the nuts to meet the installation accuracy requirements. When adjusting the ground keel, the elevation needs to be re-measured. By selecting the elevation of each point for re-measurement, adjusting the nuts and tightening the nuts, the flatness of the keel is within the required range. Finally, check the torque of the tightening nuts again. After the inspection is qualified, the nuts are spot welded. Step S5, before the secondary plastering of the keel area, the keel needs to be protected to prevent the mortar from contaminating the keel or the mortar from flowing into the keel and blocking the leak detection pipe during the plastering process; the plastering angle steel should be installed at each corner according to the drawing, so that the edge covering panel can be installed smoothly when the corner is installed after plastering. Before plastering the wall, the concrete surface should be rough. On the first day, the wall should be cleaned and soaked with water until it is saturated with water. On the second day, a 5mm thick bonding layer is applied on the soaked pool wall with mortar mixed with admixtures; on the third day, after the bonding layer is completed, the middle layer is plastered. The plastering thickness of each layer of the middle layer is 15-20mm, and the interval is 4-5 hours. If there are three layers, the third layer should not be plastered on the same day; the surface layer should be plastered and polished on the second day after the middle layer is completed. The minimum thickness of the surface layer is 10mm. The bottom of the pool is plastered with mortar mixed with admixtures. The surface of the plaster layer should be smooth. After plastering, remove the finished product protective covering film, clean the outer surface of all stainless steel to prevent it from carrying residues such as cement slurry, and there should be no gaps between the plaster layer and the base surface and steel. The surface of the final surface layer should be smooth and flat, and the plastering flatness should meet ±2mm. Use a new aluminum alloy square ruler to check, and there should be no cracks and bumps on the plastered surface. After all inspections are qualified, apply dust-proof paint to the wall and pool bottom plaster surface. Step S6, the installation of the door frame is to slowly lift the prefabricated door frame to the transport vehicle after it has passed the inspection in the workshop, and tie and fix the door frame. The specifications of the door frame are 8514mm long, 2670mm wide, and 1500mm high. The width between the U-shaped openings in the width direction of the door frame is 1m, and the weight of the door frame is 3.2T. The transport vehicle is slowly transported into the factory and moved to the area where the on-site gantry crane can lift it. The door frame is temporarily lifted to the ground by the gantry crane for storage. Due to the small space and the limited height of the gantry crane, special attention should be paid to the surrounding fences. The gantry crane trolley is driven above the door frame, and the lifting lugs are connected. The upper part of the door frame is connected with an electric hoist, and the bottom is connected with a crane trolley hook. Then the door frame is slowly lifted for trial lifting. After observing that there are no abnormalities with the crane, lifting belt and fall chain, two slip ropes are fastened at the bottom of the door frame to control the door frame during the lifting and flipping process. In order to prevent large swings or slips during the flipping process, a round hole at the bottom of the door frame is set. Use a lifting belt and a fall chain to control the door frame during the flipping process, ensuring the length is 10m. After lifting the door frame 3m, move the trolley to the door frame position and the door frame begins to flip. First, slowly lift the electric fall chain on the top of the door frame, and keep the trolley hook still. Slowly move the trolley to the outside according to the flipping progress. Carefully observe the lifting process. The chain at the bottom of the door frame should also change as the door frame flips gradually. During the whole process, the electric fall chain should be parallel to the trolley hook, and each should be in a vertical state. Slowly move the crane to verify the position, and then slowly use the electric fall chain to Lower the door frame and strictly monitor the entire lowering process. After it is lowered to the specified position, adjust the door frame appropriately, spot weld the cladding on the side of the door frame to the steel section, place two 20# I-beams on the top of the door frame, connect the door frame and the I-beams with slings, add fall chains for adjustment when necessary, then remove the crane, and finally adjust the door frame to the position, butt weld the cladding on the door frame and the wall cladding to the steel section, seal the gap between the wall and the steel cladding in the secondary casting area of ​​the door frame with sealant, and pour the secondary casting area of ​​the door frame after the sealing is completed. Step S7, before installing the cladding panels, the prefabricated cladding panels should be numbered according to the drawing numbers according to the site requirements, transported from the workshop to the construction site by a flatbed truck, temporarily stored on the ground, and hoisted and put into place in sequence from top to bottom by a crane connected to the lifting belt and shackle and the cladding panel hoisting tooling, and then spot welded to the keel after adjustment. When assembling the cladding panels, strictly follow the gap requirement of 2 to 4 mm. When spot welding, first spot weld and fix them, first spot weld the edge of the field and then spot weld the short side, and the spot welding spacing is 200 mm. If welding is not done in time after electric welding, protective measures should be taken for the weld with paper tape, and before welding the main weld of the steel cladding, The cladding panels shall be subjected to top pressure. When welding, the short ones shall be welded first and the long ones later, the horizontal ones shall be welded first and the vertical ones later, the welding shall be conducted in sections, the welding shall be conducted symmetrically and the welding shall be conducted simultaneously. When welding in sections, the temperature of the interlayers shall be controlled below 150℃ with an interval of 300mm after welding every 400mm before welding the next layer. Note that before the bottom plate cladding panels are put in place, the keels, the ground and the leak detection tubes shall be checked for foreign matter before the cladding panels are installed. After the main welds of the cladding panels are welded, the welds shall be subjected to visual inspection, vacuum box inspection, liquid penetration inspection and radiographic inspection. After the main welds are inspected and qualified, the node plate cover shall be plugged. After plugging, the welds shall be subjected to visual inspection, vacuum box inspection and liquid penetration inspection and qualified. Step S8, the water pool needs to be cleaned before the pickling and passivation of the steel cladding weld. After cleaning, the pickling and passivation paste is applied to the water pool weld, the heat-affected zone around the weld, and the contaminated cladding with a thickness of 1 to 2 mm, and maintained for 0.5 to 1 hour. The applied pickling and passivation paste is wiped off with a white cotton cloth moistened with deionized water, and the passivated surface is sprayed and washed with a high-pressure water gun until the pH value no longer changes. No corrosion points are allowed to form within at least 24 hours after pickling and passivation. If rust spots appear on the surface, the surface of all areas where the rust spots appear needs to be pickled and passivated again. The wastewater generated by pickling should be collected in the specified area for unified treatment. Step S9, before the water seal test of the water pool, all steel cladding welds are inspected and qualified, the underwater sealing door has been installed, the electrical control cabinet has been debugged, the deionized water pipeline has been connected, deionized water is available, all scaffolding in the water pool has been removed, and a temporary water receiving trough is made on the waterless side of the sealing door. After filling with water, collect the water leaking from the sealing door and collect it all in the water receiving trough. After everything is ready, open the valve and start filling with water. The filling process should be closely monitored. After the water is filled to the water pool -0.5m to reach the design elevation, it should be maintained for at least 15 days. During the full water test, the leakage of the sealing door on the waterless side does not exceed 2L per hour, which is qualified, and no water flows out of the leak detection pipe in the leak detection room, which is qualified, indicating that all the sealing welds of the water pool are qualified.

3. A method for manufacturing, installing and sealing a spent fuel pool steel cladding as claimed in claim 2, characterized in that: In step S1, the construction period of the construction site is guaranteed by prefabricating steel components in advance.

4. A method for manufacturing, installing and sealing a spent fuel pool steel cladding as claimed in claim 3, characterized in that: In step S2, after laying out the wall surface and determining the position of the expansion bolt according to the drawing requirements, holes are drilled to ensure that the holes are perpendicular to the wall surface. After the drilling and cleaning are completed, the expansion bolts are installed, and the outer ends of the expansion bolt screws are placed on the same plane. After the expansion bolt screws are installed, the first nut is screwed in to tighten them to their torque value, and the second adjustment nut is screwed into the expansion bolt screw again. The correct installation of the expansion bolts ensures the installation progress of the node plate base plate and the support plate, and also ensures the overall installation accuracy.

5. A method for manufacturing, installing and sealing a spent fuel pool steel cladding as claimed in claim 4, characterized in that: In step S3, the node plate bottom plate and the support plate are inserted into the adjustment nuts of the installed expansion bolts, and then the third fastening nut of the expansion bolt is inserted into the screw rod, and the node plate bottom plate and the support plate are adjusted to the same plane by using the adjusting screw eye and the fastening nut, so that the node plate bottom plate and the support plate on the entire surface are on the same plane, ensuring the installation accuracy and progress of the keel.

6. A method for manufacturing, installing and sealing a spent fuel pool steel cladding as claimed in claim 5, characterized in that: In step S4, corresponding keels are installed on the installed node plate bottom plate and support plate, and the keels are fixed to the support plate by welding. After the keels are welded to the node plate bottom plate and support plate, all keels are adjusted to the same plane by adjusting nuts and fastening nuts. When installing the bottom plate keel, the leak detection tube needs to be installed under the keel in advance. After the keel installation is completed and accepted, the fastening nuts are spot welded and fixed. The installation of the entire keel lays the foundation for the installation of the steel cladding panel, ensuring the overall size and flatness of the steel cladding.

7. A method for manufacturing, installing and sealing a spent fuel pool steel cladding as claimed in claim 6, characterized in that: In step S5, the installed keel area is plastered for the second time. After three layers of plastering, the plastering area between the two keels is checked for flatness using a square ruler. The flatness does not exceed 2 mm. After passing the inspection, the plastering surface layer is painted. In order to prevent the mortar from falling off during construction and affecting the flaw detection results of the main weld and the leak detection system, the finished product protection and inspection work must be done well. This work ensures the overall dimensional accuracy of the steel cladding and the pass rate of the main weld.

8. A method for manufacturing, installing and sealing a spent fuel pool steel cladding as claimed in claim 7, characterized in that: In step S6, an electric fall chain and a lifting belt are hung on the gantry crane, and then the fall chain and the lifting belt are connected by the hook of the gantry crane trolley to lift and flip the door frame into place. This method not only solves the problem of difficult installation, but also solves the shortcomings of narrow space and insufficient lifting height, ensures that large-sized heterogeneous door frames are successfully lifted and put into place at one time, achieves the installation accuracy of the steel cladding, and also ensures the overall installation accuracy of the steel cladding and the installation of the sealed door.

9. A method for manufacturing, installing and sealing a spent fuel pool steel cladding as claimed in claim 8, characterized in that: In step S7, the steel cladding lifting tools are used to safely lift the cladding panels to the installation position, especially the lifting of some cladding panels with longer lengths. The entire process is carefully deployed and strictly constructed, ultimately ensuring the installation progress of the cladding panels. During the welding process, by strictly following the welding measures, welding sequence, and setting top pressure, the weld flaw detection pass rate is greatly improved, and the weld welding quality is improved.

10. A method for manufacturing, installing and sealing a spent fuel pool steel cladding according to claim 9, characterized in that: In step S8, pickling and passivation of the weld using pickling and passivation paste effectively solves the problem of using concentrated sulfuric acid and concentrated nitric acid, greatly reduces the occurrence of safety incidents / accidents, and also improves the efficiency of pickling and passivation. In step S9, a water pool water sealing test is used to verify the sealing of the water pool welds and the sealing door. The long-term water storage test can effectively verify the leakage defects of the water pool welds, ensure the sealing of the water pool and its safety in later use, and also provide protection for the installation of other equipment and lay the foundation.

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