Ultra-large annular water tank structure of nuclear power station and construction method thereof

Abstract

The invention provides an ultra-large annular water tank structure of a nuclear power station, which comprises an annular water tank, and the annular water tank comprises a plurality of arc-shaped tank bodies; the arc-shaped box body comprises an inner ring wall plate, an outer ring wall plate, a side wall plate, a wall body corner, a top plate and a bottom plate; the inner ring wall plate and the outer ring wall plate are concentrically arranged; the inner ring wall plate is formed by splicing and fixing a plurality of inner ring sub wall plates, the outer ring wall plate is formed by splicing and fixing a plurality of outer ring sub wall plates, and the top plate is formed by splicing and fixing a plurality of top plate sub wall plates; the invention further provides a construction method of the ultra-large annular water tank structure of the nuclear power station. The ultra-large annular stainless steel water tank structure is manufactured and installed in a modularized mode, compared with a traditional post-pasting method construction technology, the on-site installation welding work amount is reduced, the welding quality is effectively guaranteed, the construction safety risk is reduced, the construction efficiency is improved, the construction period of a key path is shortened, and practicability is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of building construction, and relates to the fabrication, assembly, and installation of large-scale circular stainless steel water tanks for nuclear power plants. Specifically, it relates to an ultra-large circular water tank structure for nuclear power plants and its construction method. Background Art

[0002] Units 7 and 8 of Tianwan Nuclear Power Plant are pressurized water reactor nuclear power units of the VVER-1200 (AES-2006) reactor type, belonging to the third-generation improved nuclear power technology and being a relatively large-scale nuclear energy cooperation project. An active stainless steel water tank is installed outside the dome of the nuclear reactor building (UJA), which is an important item related to the operation safety of the nuclear power plant and belongs to the nuclear quality assurance level QA1 and the nuclear safety level LS. Active water tanks are commonly used in third-generation nuclear reactor types and have the characteristics of high height, large diameter, thin steel plates prone to deformation, and high installation accuracy requirements.

[0003] Currently, the active water tank is constructed using the traditional post-attaching method. However, if the traditional post-attaching method is used for construction, the following prominent problems exist: 1) It is easy to have formwork swelling after concrete pouring, resulting in quality problems such as large dimensional deviations and depressions in the keel; 2) There are many on-site welds, and it is difficult to ensure the welding quality, with a risk of leakage; 3) The construction period is long, occupying the main construction line and affecting the overall progress. With the acceleration of the nuclear power plant construction pace and the improvement of construction requirements, the traditional post-attaching installation construction technology is difficult to meet the needs of nuclear power plant construction. Therefore, the present invention designs a modular construction technology of the pre-attaching method for stainless steel water tanks to solve the above problems. Summary of the Invention

[0004] In order to overcome the problems existing in the prior art, the present invention provides an ultra-large circular water tank structure for nuclear power plants and its construction method, which solves the problems in the prior art such as limited on-site resources at the nuclear power plant construction site, many water tank welds, large welding volume, large welding deformation, difficult overall dimension control, long cross-construction time with the internal structure, high construction safety operation risk, and long occupation of the critical path construction period.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] (1) The present invention provides a super-large annular water tank structure for a nuclear power plant, including an annular water tank, and the annular water tank includes a plurality of arc-shaped boxes; the arc-shaped box includes an inner ring wall panel, an outer ring wall panel, a side wall panel, a wall corner, a top plate and a bottom plate; the inner ring wall panel and the outer ring wall panel are concentrically arranged, the side wall panel and the wall corner are fixed on both sides of the inner ring wall panel and the outer ring wall panel, the top plate is fixed on the top of the inner ring wall panel and the outer ring wall panel, and the bottom plate is fixed on the bottom of the inner ring wall panel and the outer ring wall panel; the inner ring wall panel is fixedly spliced by a plurality of inner ring sub-wall panels, the outer ring wall panel is fixedly spliced by a plurality of outer ring sub-wall panels, and the top plate is fixedly spliced by a plurality of top plate sub-wall panels.

[0007] Further, ring plate angle steel ribs are respectively arranged on the outer side surfaces of the inner ring sub-wall panel and the outer ring sub-wall panel; the ring plate angle steel ribs include circumferential angle steel ribs and longitudinal angle steel ribs; the circumferential angle steel ribs are distributed circumferentially along the inner ring sub-wall panel / outer ring sub-wall panel and are fixedly connected with the inner ring sub-wall panel / outer ring sub-wall panel; the longitudinal angle steel ribs are vertically distributed and are fixedly connected with the inner ring sub-wall panel / outer ring sub-wall panel.

[0008] Further, a plurality of flat steel ribs are arranged on the outer surface of the top plate sub-wall panel, the flat steel ribs coincide with the diameter of the annular water tank and are fixedly connected with the top plate sub-wall panel; a plurality of side plate angle steel ribs are arranged on the outer surface of the side wall panel, and the side plate angle steel ribs include horizontal angle steel ribs and vertical angle steel ribs, and the horizontal angle steel ribs and the vertical angle steel ribs are fixedly connected with the side wall panel.

[0009] Further, through holes are arranged on the flanges of the ring plate angle steel ribs, and anchoring steel bars are arranged in the through holes; anchoring steel bars are arranged on the flat steel ribs, and the anchoring steel bars are equidistantly distributed on the flat steel ribs.

[0010] (2) The present invention also provides a construction method for the above-mentioned super-large annular water tank structure of a nuclear power plant, including:

[0011] S1. Prepare a plurality of formed keels, fixedly connect the inner sides of the outer ring sub-wall panel and the inner ring sub-wall panel with the corresponding formed keels respectively, and weld the circumferential angle steel ribs and the longitudinal angle steel ribs on the outer sides of the outer ring sub-wall panel and the inner ring sub-wall panel;

[0012] S2. Transport each module combined in step S1 to the construction site. First, fixedly splice a plurality of inner ring sub-wall panels to form an inner ring wall panel, then fixedly splice a plurality of outer ring sub-wall panels into an inner and outer ring wall panel, and then fix the side wall panel and the wall corner on both sides of the inner ring wall panel and the outer ring wall panel;

[0013] S3. Lay wooden templates at the intervals of the formed keels on the inner sides of the outer ring sub-wall panel and the inner ring sub-wall panel, and fix them with wooden keels. Set equidistant vertical channel steels on the side of the wooden keels facing away from the wooden templates, and finally set scaffolding pipes between the two vertical channel steels for support;

[0014] S4. Pour the wall concrete outside the outer ring sub-wall panel and the inner ring sub-wall panel, and weld the top plate sub-wall panel to the tops of the outer ring sub-wall panel and the inner ring sub-wall panel.

[0015] S5. Demolish the formed keel, wooden formwork, wooden keel, vertical channel steel and scaffolding pipes, and finally install the bottom plate.

[0016] Further, the radian of the formed keel is the same as that of the annular water tank structure, and it includes a number of circumferential channel steels and longitudinal channel steels. Each group of circumferential channel steels is distributed in parallel, and the longitudinal channel steels are distributed in parallel, and the longitudinal channel steels are perpendicularly fixed to each circumferential channel steel.

[0017] Further, in the formed keel, the circumferential channel steels distributed at the uppermost and lowermost openings are provided with holes on the flange on the side contacting the outer ring sub-wall panel / inner ring sub-wall panel, and are fixedly connected to the outer ring sub-wall panel / inner ring sub-wall panel through bolts.

[0018] Further, the method for fixedly connecting the outer ring sub-wall panel and the inner ring sub-wall panel with the formed keel is as follows: Place the formed keel on the formwork support and fix it; Place the stainless steel plate on the formed keel, and place the counterweight on the stainless steel plate, and form it using the radian of the formed keel to obtain the outer ring sub-wall panel / inner ring sub-wall panel; Fix the outer ring sub-wall panel / inner ring sub-wall panel and the formed keel through stainless steel bolts; Remove the connection between the formed keel and the formwork support.

[0019] Further, the formwork support includes a convex formwork support and a concave formwork support; The convex formwork support is used for the fixation of the outer ring sub-wall panel and the formed keel, and the concave formwork support is used for the fixation of the inner ring sub-wall panel and the formed keel.

[0020] Further, the convex formwork support includes a first bottom frame, a first arc-shaped channel steel, a first straight channel steel and a first channel steel column; The first channel steel columns are distributed in columns and fixed on the first bottom frame, and the height of the first channel steel columns in each column gradually decreases from the middle to both ends; There are two first arc-shaped channel steels, which are fixedly connected to the first channel steel columns distributed at the ends in each column; The number of the first straight channel steels is the same as the number of columns of the first channel steel columns, and they are fixedly installed on the tops of the first channel steel columns in the same column, and both ends of the first straight channel steel are respectively fixedly connected to the two first arc-shaped channel steels; The concave formwork support includes a second bottom frame, a second arc-shaped channel steel, a second straight channel steel and a second channel steel column; The second channel steel columns are distributed in columns and fixed on the second bottom frame, and the height of the second channel steel columns in each column gradually increases from the middle to both ends; There are two second arc-shaped channel steels, which are fixedly connected to the second channel steel columns distributed at the ends in each column; The number of the second straight channel steels is the same as the number of columns of the second channel steel columns, and they are fixedly installed on the tops of the second channel steel columns in the same column, and both ends of the second straight channel steel are respectively fixedly connected to the two second arc-shaped channel steels.

[0021] The beneficial effects of the present invention are as follows:

[0022] (1) The present invention proposes a construction technology of the pre - pasting method for assembled stainless - steel cladding, which realizes modular fabrication and installation of the ultra - large - scale annular stainless - steel water tank structure. Compared with the traditional post - pasting construction technology, it reduces the on - site installation and welding workload, and effectively guarantees the welding quality;

[0023] (2) The present invention develops and designs a forming keel and a detachable steel - wood combined support formwork dedicated to the arc - shaped water tank wall panel, which effectively controls welding deformation and geometric dimensions, effectively resists and eliminates the lateral pressure generated by the pouring of the outer - side concrete, and ensures that the high - precision technical indicators such as the verticality and radius of the stainless - steel water tank meet the design requirements;

[0024] (3) The present invention pioneers the construction technology of the pre - pasting method for assembled stainless - steel cladding, which effectively guarantees the installation accuracy of the stainless - steel water tank, reduces the construction safety risk, improves the construction efficiency, shortens the construction period of the critical path, and significantly improves the construction quality, saves costs on the premise of reducing the occupation of the construction site resources and avoiding the use of large cranes, laying a solid foundation for the successful realization of major milestone nodes such as the thermal type of the nuclear power plant system. Description of the Drawings

[0025] Figure 1 is a schematic diagram of the ultra - large - scale annular water tank structure of the nuclear power plant of the present invention;

[0026] Figures 2 - 3 is a schematic diagram of the arc - shaped box structure of the present invention;

[0027] Figure 4 is a construction process flow chart of the stainless - steel water tank module structure of the present invention;

[0028] Figures 5 - 6 is a schematic diagram of the forming keel structure of the present invention;

[0029] Figure 7 is a schematic diagram of the concave - type formwork support of the present invention;

[0030] Figure 8 is a schematic diagram of the convex - type formwork support of the present invention;

[0031] Figure 9 is a schematic diagram of the installation of the detachable steel - wood combined support of the present invention;

[0032] Figure 10 is a connection node diagram of the inner - ring sub - wall panel / outer - ring sub - wall panel and the forming keel;

[0033] The marks in the drawings are:

[0034] 1. Arc-shaped box body; 11. Inner ring sub-wall panel; 111. Cover panel; 12. Outer ring sub-wall panel; 13. Side wall panel; 14. Top plate sub-wall panel; 15. Wall corner; 16. Ring plate angle steel rib; 17. Flat steel rib; 18. Through piece; 19. Bottom plate corner; 2. Formed keel; 21. Circumferential channel steel; 22. Longitudinal channel steel; 23. Isolation backing plate; 3. Convex mold frame; 31. First arc-shaped channel steel; 32. First straight channel steel; 33. First channel steel column; 4. Demountable steel-wood combined support; 41. Wood formwork; 42. Wood keel; 43. Vertical channel steel; 44. Scaffolding pipe; 5. Stainless steel bolt; 6. Concave mold frame; 61. Second arc-shaped channel steel; 62. Second straight channel steel; 63. Second channel steel column. Detailed implementation mode

[0035] In order to make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] Embodiment 1

[0037] An embodiment of the present invention provides a super-large annular water tank structure for a nuclear power plant, including an annular water tank. The annular water tank includes 4 arc-shaped box bodies 1, as Figure 1 shown.

[0038] Among them, the arc-shaped box body 1 includes an inner ring wall panel, an outer ring wall panel, a side wall panel, a wall corner, a top plate and a bottom plate. The above structures are made of stainless steel. The inner ring wall panel and the outer ring wall panel are concentrically arranged. The side wall panel and the wall corner are fixed on both sides of the inner ring wall panel and the outer ring wall panel. The top plate is fixed on the top of the inner ring wall panel and the outer ring wall panel, and the bottom plate is fixed on the bottom of the inner ring wall panel and the outer ring wall panel. Water inlet holes and water outlet holes are provided on the top plate and / or the outer ring wall panel for water conveyance and drainage of the annular water tank. The inner ring wall panel, the outer ring wall panel, the side wall panel, the wall corner, the top plate and the bottom plate form a closed water tank structure, serving as an important functional water tank for the nuclear power plant.

[0039] As Figures 2 - 3 shown, the inner ring wall panel is fixedly spliced by three inner ring sub-wall panels 11, the outer ring wall panel is fixedly spliced by four outer ring sub-wall panels 12, and the top plate is fixedly spliced by three top plate sub-wall panels 14. The sub-wall panels are assembled and welded on site. The inner ring wall panel, the outer ring wall panel and the side wall panel 13 are connected by the wall corner 15.

[0040] As Figures 2 - 3As shown, circumferential plate angle ribs 16 are respectively arranged on the outer side surfaces of the inner ring sub-wall plate 11 and the outer ring sub-wall plate 12. The circumferential plate angle ribs 16 include circumferential angle ribs and longitudinal angle ribs. The circumferential angle ribs are distributed circumferentially along the inner ring sub-wall plate 11 / outer ring sub-wall plate 12 and are fixedly connected to the inner ring sub-wall plate 11 / outer ring sub-wall plate 12; the longitudinal angle ribs are vertically distributed and are fixedly connected to the inner ring sub-wall plate 11 / outer ring sub-wall plate 12. The distance from the angle rib at the outer edge of each sub-wall plate to the edge of the wall plate is 100 mm. The longitudinal and circumferential angle ribs are connected by welding, and the angle ribs and the wall plate are connected by intermittent welding. The angle ribs form a square around the through-piece (water outlet), and the distance from the edge of the through-piece is at least 100 mm.

[0041] A plurality of flat steel ribs 17 are arranged on the outer surface of the top plate sub-wall plate 14. The flat steel ribs 17 coincide with the diameter of the annular water tank and are fixedly connected to the top plate sub-wall plate 14; a plurality of through-pieces 18 (water inlets) are also arranged on the top plate sub-wall plate 14 for water conveyance. A plurality of side plate angle ribs are arranged on the outer surface of the side wall plate. The side plate angle ribs include horizontal angle ribs and vertical angle ribs, and the horizontal angle ribs and the vertical angle ribs are fixedly connected to the side wall plate.

[0042] As Figures 2 - 3 shown, through holes (hole diameter Φ10, spacing 200 mm) are arranged on the flange of the circumferential plate angle rib 16, and Φ8 mm anchoring steel bars are arranged in the through holes for anchoring between the wall plate and the concrete. Φ8 mm anchoring steel bars are welded on the flat steel rib 17 for anchoring between the top plate and the concrete, and the anchoring steel bars are equally spaced (every 200 mm) on the flat steel rib 17. The flat steel rib 17 forms a square around the through-piece 18, and the distance from the edge of the through-piece 18 is at least 200 mm.

[0043] Embodiment 2

[0044] The present invention also provides a construction method for the super-large annular water tank structure of a nuclear power plant, including the following steps:

[0045] Step 1: Fabrication of the formed keel:

[0046] The radian of the formed keel 2 is the same as that of the annular water tank structure, and it includes a plurality of circumferential channel steels 21 and longitudinal channel steels 22. Each group of circumferential channel steels 21 is parallelly distributed, the longitudinal channel steels 22 are parallelly distributed, and the longitudinal channel steels 22 are perpendicularly fixed to each circumferential channel steel 21, as shown in Figures 5 - 6 . The preparation process is as follows:

[0047] Use a bending machine to bend several channel steels into a circular shape to form the circumferential channel steel 21, and ensure that the outer diameter of the arc-shaped channel steel for the outer ring wall keel is the same as the inner diameter of the outer ring sub-wall panel 12, and the inner diameter of the arc-shaped channel steel for the inner ring wall keel is the same as the outer diameter of the inner ring sub-wall panel 11; splice the straight longitudinal channel steel 22 with the arc-shaped circumferential channel steel 21 to form a formed keel 2 and apply anti-rust paint. The outer dimension of the formed keel 2 matches that of the outer ring sub-wall panel 12 / inner ring sub-wall panel 11.

[0048] Step Two: Fabrication of the formwork frame:

[0049] The formwork frame includes a convex formwork frame 3 and a concave formwork frame 6. Among them, the convex formwork frame 3 is used for the fixation, storage, and transportation of the outer ring sub-wall panel 12 and the formed keel 2, and the concave formwork frame 6 is used for the fixation, storage, and transportation of the inner ring sub-wall panel 11 and the formed keel 2.

[0050] As Figures 7 - 8 shown, the convex formwork frame 3 includes a first bottom frame, a first arc-shaped channel steel 31, a first straight channel steel 32, and a first channel steel column 33. The first channel steel columns 33 are distributed in columns and fixed on the first bottom frame. The height of each column of the first channel steel columns 33 gradually decreases from the middle to both ends. Two first arc-shaped channel steels 31 are provided and are fixedly connected to the first channel steel columns 33 distributed at the ends of each column of the first channel steel columns 33. The number of the first straight channel steels 32 is the same as the number of columns of the first channel steel columns 33, and they are fixedly installed on the tops of the same column of the first channel steel columns 33. Moreover, both ends of the first straight channel steel 32 are respectively fixedly connected to the two first arc-shaped channel steels 31.

[0051] The concave formwork frame 6 includes a second bottom frame, a second arc-shaped channel steel 61, a second straight channel steel 62, and a second channel steel column 63. The second channel steel columns 63 are distributed in columns and fixed on the second bottom frame. The height of each column of the second channel steel columns 63 gradually increases from the middle to both ends. Two second arc-shaped channel steels 61 are provided and are fixedly connected to the second channel steel columns 63 distributed at the ends of each column of the second channel steel columns 63. The number of the second straight channel steels 62 is the same as the number of columns of the second channel steel columns 63, and they are fixedly installed on the tops of the same column of the second channel steel columns 63. Moreover, both ends of the second straight channel steel 62 are respectively fixedly connected to the two second arc-shaped channel steels 61.

[0052] The fabrication methods of the convex formwork frame 3 and the concave formwork frame 6 are similar. Specifically:

[0053] Use a bending machine to bend several channel steels into a circular shape to form arc-shaped channel steels, whose radian and radius respectively match those of the inner and outer ring wall formed keels 2. Weld straight channel steels to each other to form a horizontal frame, set channel steel columns with different heights at equal intervals around the horizontal frame, the height of the channel steel columns matches that of the arc-shaped channel steels, and finally weld and fix the arc-shaped channel steels to the channel steel columns to finally form the formwork frame and apply anti-rust paint.

[0054] Step 3. Assembly of the formed keel and the formwork rack:

[0055] Place the formed keel on the corresponding formwork rack and fix it with bolts around.

[0056] Step 4. Assembly of the outer ring sub-wall panel, the inner ring sub-wall panel and the formed keel:

[0057] On a flat stainless-steel platform, weld and splice several stainless-steel cladding panels 111 into the outer ring sub-wall panel 12 and the inner ring sub-wall panel 11, leaving a margin at the edges.

[0058] Place the outer ring sub-wall panel 12 and the inner ring sub-wall panel 11 on the formed keel 2, and place several counterweights on them. Shape them using the curvature of the formed keel 2, and fix the margins at the upper and lower edges of the wall panels to the formed keel 2 with stainless-steel bolts 5; weld circumferential angle steel ribs and longitudinal angle steel ribs on the outer side of the wall panels. The formed keel 2 and the outer ring sub-wall panel 12 together form the outer ring sub-module, and the formed keel 2 and the inner ring sub-wall panel 11 together form the inner ring sub-module; loosen the connection bolts between the formed keel 2 and the formwork rack, and hoist it to the storage formwork rack for transportation.

[0059] Step 5. Installation of the inner ring wall panel, the outer ring wall panel, the side wall panel and the wall corner:

[0060] Transport all the sub-modules to the on-site assembly site for on-site hoisting. First, install the three inner ring sub-modules of the inner ring wall panel, then install the four outer ring sub-modules of the outer ring wall panel, and finally install the two side wall panels 13 and the wall corner 15. Align and weld the longitudinal seams between the sub-modules and the longitudinal seams between the corners and the sub-modules to form a complete wall panel. During the binding of the wall reinforcement, install the anchor reinforcement through the holes reserved in the angle steel ribs.

[0061] Step 6. Installation of the detachable steel-wood combined support:

[0062] As Figure 9 shown, lay the wooden formwork 41 at the intervals of the formed keel 2 on the inner sides of the outer ring sub-wall panel 12 and the inner ring sub-wall panel 11, and fix it with the wooden keel 42. Set equidistant vertical channel steels 43 on the side of the wooden keel 42 facing away from the wooden formwork 41. Finally, set the scaffolding pipes 44 between the two vertical channel steels 43, so that the scaffolding pipes 44 horizontally support against the flanges of the vertical channel steels 43.

[0063] Step 7. Installation of the top plate:

[0064] Pour the wall concrete on the outer sides of the outer ring sub-wall panel 12 and the inner ring sub-wall panel 11, remove the surplus at the upper mouth of the wall panel, install the three top plate sub-modules, and lap and weld the top plate sub-modules with the backing plates pre-installed at the upper mouth of the wall panel. Install flat steel ribs on the upper side of the butt welds between the top plate sub-modules as backing plates.

[0065] Step 8. Installation of the bottom plate:

[0066] Remove the steel-wood combined supports 4 and the formed keels 2 inside the box body, remove the surplus at the lower ends of the wall panels 11, 12, and 13 of the wall, and install the bottom plate wall panels and the bottom plate corners 19.

[0067] The present invention solves the problems of insufficient construction site resources for the ultra-large ring-shaped stainless steel water tank in nuclear power plants, large amount of on-site welding, high construction safety operation risks, and long occupation of the critical path construction period. By using the method of the present invention, each sub-module of the box body is prefabricated in the workshop and transported to the site for assembly and installation. The inside of the box body adopts detachable steel-wood combined supports, which are removed after the concrete pouring outside the box body is completed.

[0068] Embodiment 3

[0069] Taking the construction of the ultra-large ring-shaped stainless steel water tank structure outside the reactor dome of Unit 7 in the fourth phase of Tianwan Nuclear Power Project as an example, the implementation mode of the present invention is specifically introduced:

[0070] The construction process of the ultra-large ring-shaped stainless steel water tank structure is shown in Figure 4 .

[0071] (1) Fabrication of the formed keel

[0072] ① Channel steel cutting

[0073] The channel steel is [14a. The channel steel is mainly divided into two types. One is the straight channel steel, which is directly cut into the required size by a profile cutting machine. The other is the circumferential channel steel, which needs to be bent.

[0074] ② Channel steel bending

[0075] First, let the machine run without load to ensure that the machine is fault-free, and then bend the channel steel. The bending process should be gradual, and the bending stroke each time should not be too large. Check the bending radius at any time during the process. After the first component is bent and inspected qualified, the bending of the remaining components can be carried out successively. The circumferential channel steel 21 is fabricated by this method.

[0076] ③ Splicing

[0077] Adopt the welding process to splice the longitudinal channel steel 22 and the circumferential channel steel 21 into the formed keel 2, and apply anti-rust paint. The external dimensions of the formed keel 2 match the wall panel sub-module of the wall.

[0078] (2) Fabrication of the formwork support

[0079] ① Channel steel cutting

[0080] The channel steel is [14a]. The channel steel is mainly divided into two types. One is the straight channel steel and the vertical channel steel, which are directly cut into the required sizes using a profile cutting machine. The other is the circumferential channel steel, which needs to be bent.

[0081] ② Bending of the channel steel

[0082] First, let the machine run without load to ensure it is fault-free, and then bend the channel steel. The bending process should be gradual, and the bending stroke each time should not be too large. Check the bending radius at any time during the process. After the first component is bent and inspected to be qualified, the bending of the remaining components can be carried out successively. The arc-shaped channel steel is obtained by this method.

[0083] ③ Assembly

[0084] Weld the straight channel steels to each other to form a horizontal frame. Set channel steel columns with different heights at equal intervals around the horizontal frame. The height of the channel steel columns matches that of the arc-shaped channel steel. Finally, weld and fix the arc-shaped channel steel to the channel steel columns to finally form a formwork frame and apply anti-rust paint.

[0085] (3) Combination of the formed keel and the formwork frame

[0086] Place the formed keel on the corresponding formwork frame and fix it with bolts around.

[0087] (4) Combination of the outer ring sub-wall panel and the inner ring sub-wall panel with the formed keel

[0088] ① Manufacture of the outer ring sub-wall panel and the inner ring sub-wall panel

[0089] On a flat stainless steel platform, weld and splice several stainless steel plates 111 to form an outer ring sub-wall panel 12 and an inner ring sub-wall panel 11, leaving a margin at the edges. Control the welding deformation during the splicing process, and the flatness after the steel plates are spliced is within 5 mm.

[0090] ② Sub-module forming

[0091] Place the outer ring sub-wall panel 12 and the inner ring sub-wall panel 11 on the formed keel 2, and place several counterweights on them. Use the curvature of the formed keel 2 to form, and fix the margins at the upper and lower edges of the wall panel to the formed keel 2 with stainless steel bolts 5. The formed keel 2 and the outer ring sub-wall panel 12 together form an outer ring sub-module, and the formed keel 2 and the inner ring sub-wall panel 11 together form an inner ring sub-module.

[0092] ③ Welding of angle steel ribs

[0093] Weld circumferential angle steel ribs and longitudinal angle steel ribs on the outside of the wall panel. During the welding process, use counterweights to press at the intervals of the angle steel ribs to prevent welding deformation.

[0094] ④ Storage

[0095] Open the connecting bolts between the formed keel 2 and the formwork support, hoist it to the storage formwork support for transportation.

[0096] (5) Installation of the inner ring wall panel, outer ring wall panel, side wall panel and wall corner:

[0097] Transport all sub-modules to the on-site assembly site for on-site hoisting. First, install the three inner ring sub-modules of the inner ring wall panel, then install the four outer ring sub-modules of the outer ring wall panel, and finally install the two side wall panels 13 and the wall corner 15. Pair and weld the longitudinal joints between the sub-modules and the longitudinal joints between the corners and the sub-modules to form a complete week of wall panels. During the binding of the wall reinforcement, install the anchor reinforcement through the holes reserved by the angle steel ribs.

[0098] (6) Installation of the detachable steel-wood combined support

[0099] Lay the wooden formwork 41 at the intervals of the formed keel (2) on the inner sides of the outer ring sub-wall panel 12 and the inner ring sub-wall panel 11, and fix it with the wooden keel 42. Set equidistant vertical channel steels 43 on the side of the wooden keel 42 facing away from the wooden formwork 41. Finally, set the scaffolding pipes 44 between the two vertical channel steels 43 inside and outside, so that the scaffolding pipes 44 horizontally support against the flanges of the vertical channel steels 43.

[0100] (7) Installation of the top plate

[0101] Pour the wall concrete on the outer sides of the outer ring sub-wall panel 12 and the inner ring sub-wall panel 11, remove the surplus at the upper mouth of the wall panel, install the three top plate sub-modules, and lap and weld the top plate sub-modules with the backing plates pre-installed at the upper mouth of the wall panel. Install the flat steel ribs on the upper side of the butt welds between the top plate sub-modules as backing plates.

[0102] (8) Installation of the bottom plate:

[0103] Remove the steel-wood combined support 4 and the formed keel 2 inside the box body, remove the surplus at the lower mouth of the wall panels 11, 12, 13, and install the bottom plate wall panel and the bottom plate corner 19.

[0104] Adopting the solution of the present invention for the construction of the super-large annular stainless steel water tank structure outside the dome of the fourth phase of Tianwan Nuclear Power Project has achieved the following beneficial effects:

[0105] 1) Construction period

[0106] The construction period of the super-large annular stainless steel water tank structure outside the dome of Unit 7 of Tianwan Nuclear Power Plant is 80 days, 40 days ahead of the third-level schedule.

[0107] 2) Weld quality

[0108] The first-pass qualification rate of all butt weld visual inspections (VT), vacuum box inspections (LT), penetrant inspections (PT), and radiographic inspections (RT) reaches 100%.

[0109] 3) Installation quality

[0110] The radius deviation of the water tank is within ±20 mm, the perpendicularity deviation is within 10 mm, and the angular deviation is within ±3′, meeting the design requirements.

[0111] 4) Construction safety

[0112] Most of the processes of the box body construction are completed in the workshop. Only module assembly and penetration piece installation are required on site, which not only reduces the frequency of high-altitude operations on site but also reduces the cross-operation time with the construction of the shell steel bars, formwork, and concrete.

[0113] 5) Economic benefits

[0114] Compared with the traditional construction methods in the past, adopting this method for construction can reduce a large number of on-site welds, save the input costs of materials, labor, and equipment. Calculated based on one nuclear power unit, the comprehensive economic benefits are approximately 1.16 million yuan.

[0115] A super-large ring-shaped stainless steel water tank outside the nuclear power plant dome and its construction method of the present invention divide the water tank wall and roof into several self-sub-modules, prefabricate them in the workshop, and install them after transporting them to the site, achieving the maximum degree of assembly construction, reducing on-site installation welds and cross-construction with civil engineering.

[0116] The present invention is constructed on the steel platform in the workshop, with a large degree of freedom in the operation space and high control precision of the box body. The formed keel and formwork frame are combined to form, and the operation is simple. At the same time, when pouring concrete on site, the designed steel-wood combined support effectively supports the lateral pressure caused by the concrete pouring on the outside of the box body, and can effectively control the geometric dimensions of the box body to meet the precision requirements. The allowable deviation of the misalignment of the steel plate splicing seam is 0 - 1 mm, the allowable radius deviation is ±20 mm, and the allowable perpendicularity deviation is 10 mm. The new process provided by the present invention adopts the concept of integral assembly, which can ensure that the installation quality of the box body better meets the design requirements.

[0117] The above is only the preferred implementation mode of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions within the idea of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, several improvements and refinements made without departing from the principle of the present invention should be regarded as within the protection scope of the present invention.

Claims

1. A super-large annular water tank structure for a nuclear power plant, characterized in that it includes an annular water tank, and the annular water tank includes a plurality of arc-shaped boxes (1); The arc-shaped box (1) includes an inner ring wall panel, an outer ring wall panel, a side wall panel, a wall corner, a top plate and a bottom plate; the inner ring wall panel and the outer ring wall panel are concentrically arranged, the side wall panel and the wall corner are fixed on both sides of the inner ring wall panel and the outer ring wall panel, the top plate is fixed on the top of the inner ring wall panel and the outer ring wall panel, and the bottom plate is fixed on the bottom of the inner ring wall panel and the outer ring wall panel; The inner ring wall panel is fixedly spliced by a plurality of inner ring sub-wall panels (11), the outer ring wall panel is fixedly spliced by a plurality of outer ring sub-wall panels (12), and the top plate is fixedly spliced by a plurality of top plate sub-wall panels (14).

2. The super-large annular water tank structure for a nuclear power plant according to claim 1, characterized in that ring plate angle steel ribs (16) are respectively arranged on the outer side surfaces of the inner ring sub-wall panel (11) and the outer ring sub-wall panel (12); The ring plate angle steel rib (16) includes a circumferential angle steel rib and a longitudinal angle steel rib; the circumferential angle steel rib is distributed circumferentially along the inner ring sub-wall panel (11) / outer ring sub-wall panel (12) and is fixedly connected to the inner ring sub-wall panel (11) / outer ring sub-wall panel (12); the longitudinal angle steel rib is vertically distributed and is fixedly connected to the inner ring sub-wall panel (11) / outer ring sub-wall panel (12).

3. The super-large annular water tank structure for a nuclear power plant according to claim 2, characterized in that a plurality of flat steel ribs (17) are arranged on the outer surface of the top plate sub-wall panel (14), and the flat steel ribs (17) coincide with the diameter of the annular water tank and are fixedly connected to the top plate sub-wall panel (14).

4. The super-large annular water tank structure for a nuclear power plant according to claim 3, characterized in that through holes are arranged on the flanges of the ring plate angle steel rib (16), and anchoring steel bars are arranged in the through holes; anchoring steel bars are arranged on the flat steel rib (17), and the anchoring steel bars are equidistantly distributed on the flat steel rib (17).

5. The construction method of the ultra-large annular water tank structure of a nuclear power plant according to claim 1, characterized in that, It includes: S1. Prepare a plurality of formed keels (2), fixedly connect the inner sides of the outer ring sub-wall panel (12) and the inner ring sub-wall panel (11) to the corresponding formed keels (2) respectively, and weld circumferential angle steel ribs and longitudinal angle steel ribs on the outer sides of the outer ring sub-wall panel (12) and the inner ring sub-wall panel (11); S2. Transport each module combined in step S1 to the construction site. First, fixedly connect a plurality of inner ring sub-wall panels (11) to form an inner ring wall panel, then fixedly connect a plurality of outer ring sub-wall panels (12) to form an inner and outer ring wall panel, and then fix the side wall panel and the wall corner on both sides of the inner ring wall panel and the outer ring wall panel; S3. Lay formwork (41) at the intervals of the formed keels (2) on the inner sides of the outer ring sub-wall panel (12) and the inner ring sub-wall panel (11), and fix it with wooden keels (42). Vertically arranged channel steels (43) are arranged at equal distances on the side of the wooden keel (42) facing away from the formwork (41), and finally, scaffolding pipes (44) are arranged between the two vertical channel steels (43) for support; S4. Pour the wall concrete on the outer side of the outer ring sub-wall panel (12) and the inner ring sub-wall panel (11), and weld the top plate sub-wall panel (14) to the tops of the outer ring sub-wall panel (12) and the inner ring sub-wall panel (11). S5. Demolish the formed keel (2), wooden formwork (41), wooden keel (42), vertical channel steel (43) and scaffolding pipe (44), and finally install the bottom plate.

6. The construction method of the super-large annular water tank structure of a nuclear power plant according to claim 5, characterized in that the radian of the formed keel (2) is the same as that of the annular water tank structure, and it includes a plurality of circumferential channel steels (21) and longitudinal channel steels (22). Each group of circumferential channel steels (21) is distributed in parallel, the longitudinal channel steels (22) are distributed in parallel, and the longitudinal channel steels (22) are perpendicularly fixed to each circumferential channel steel (21).

7. The construction method of the super-large annular water tank structure of a nuclear power plant according to claim 6, characterized in that in the formed keel (2), the circumferential channel steels (21) distributed at the uppermost and lowermost openings are provided with holes in the flange on the side in contact with the outer ring sub-wall panel (12) / inner ring sub-wall panel (11), and are fixedly connected to the outer ring sub-wall panel (12) / inner ring sub-wall panel (11) through bolts.

8. The construction method of the super-large annular water tank structure of a nuclear power plant according to claim 5, characterized in that the method for fixedly connecting the outer ring sub-wall panel (12) and the inner ring sub-wall panel (11) to the formed keel (2) is as follows: Place the formed keel (2) on the formwork support and fix it; Place the stainless steel plate on the formed keel (2), and place counterweights on the stainless steel plate. Use the radian of the formed keel (2) to form the outer ring sub-wall panel (12) / inner ring sub-wall panel (11); Fix the outer ring sub-wall panel (12) / inner ring sub-wall panel (11) to the formed keel (2) through stainless steel bolts; Remove the connection between the formed keel (2) and the formwork support.

9. The construction method of the super-large annular water tank structure of a nuclear power plant according to claim 8, characterized in that the formwork support includes a convex formwork support (3) and a concave formwork support (6); the convex formwork support (3) is used for fixing the outer ring sub-wall panel (12) to the formed keel (2), and the concave formwork support (6) is used for fixing the inner ring sub-wall panel (11) to the formed keel (2).

10. The construction method of the super-large annular water tank structure of a nuclear power plant according to claim 9, characterized in that The convex formwork support (3) includes a first chassis, a first arc channel steel (31), a first straight channel steel (32) and a first channel steel column (33); the first channel steel columns (33) are distributed in columns and fixed on the first chassis, and the height of the first channel steel columns (33) in each column gradually decreases from the middle to the two ends; two first arc channel steels (31) are provided and fixedly connected to the first channel steel columns (33) distributed at the ends in each column; the number of the first straight channel steels (32) is the same as the number of columns of the first channel steel columns (33), fixedly installed on the tops of the first channel steel columns (33) in the same column, and the two ends of the first straight channel steel (32) are respectively fixedly connected to the two first arc channel steels (31). The concave formwork support (6) includes a second chassis, a second arc channel steel (61), a second straight channel steel (62) and a second channel steel column (63); the second channel steel columns (63) are distributed in columns and fixed on the second chassis, and the height of the second channel steel columns (63) in each column gradually increases from the middle to the two ends; two second arc channel steels (61) are provided and fixedly connected to the second channel steel columns (63) distributed at the ends in each column; the number of the second straight channel steels (62) is the same as the number of columns of the second channel steel columns (63), fixedly installed on the tops of the second channel steel columns (63) in the same column, and the two ends of the second straight channel steel (62) are respectively fixedly connected to the two second arc channel steels (61).

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