Steel box for heavy water reactor pressure vessel replacement

Abstract

The utility model relates to the technical field of radioactive material protection provides a steel box for heavy water reactor pressure pipeline replacement, including box and lid, the box and lid are connected fixed through dismounting subassembly, the box includes box frame, the box frame includes two lower cross beams, is equipped with the placement hole on the lower cross beam, the placement hole between two lower cross beams is welded with fork groove, and the lower cross beam adopts channel section steel to make, and the box stand adopts square tube to make, and the upper cross beam, upper longitudinal beam adopts rectangular tube to make, and the channel section steel, square tube and rectangular tube are welded as the box frame, so that the steel box overall dead weight is lighter, and the welding construction quantity is less, and the production is convenient, the placement hole is equipped with in the lower cross beam, and the forklift handling is convenient, is applicable to the place of lifting height restriction.

Description

Technical Field

[0001] This utility model relates to the technical field of radioactive material protection, and in particular to a steel box for replacing pressure pipelines in heavy water reactors. Background Technology

[0002] During long-term operation, heavy water reactors face the problem of high tritium concentration accumulation, which poses a potential threat to the safe operation of the reactor. To ensure the safe and stable operation of heavy water reactors, critical components such as pressure tubes need to be replaced regularly at certain intervals.

[0003] During the replacement of the entire reactor core pressure piping, a large amount of low- and intermediate-level radioactive metal waste is generated. Improper handling of this waste can have adverse effects on the environment and human health, thus requiring specialized containers for its containment, transportation, and temporary storage. However, existing containers for this type of radioactive metal waste have several shortcomings: First, some containers have unreasonable structural designs, using heavy materials or complex welding structures, resulting in significant weight, extensive welding work, and difficulty in fabrication; second, there is a lack of suitable handling structures, making flexible handling difficult in areas with limited lifting height, and some handling structure designs affect the strength and rigidity of the container body; third, the strength of critical parts such as the bottom corners is insufficient, and drops during transportation can easily expose the waste inside; fourth, the protective design is not flexible and reasonable enough, often excessively increasing the overall weight when enhanced radioactive protection is needed, which is detrimental to use. Furthermore, existing containers often suffer from insufficient sealing and structural strength at welded joints, easily leading to the risk of radioactive material leakage and failing to meet the actual needs of safe handling. Therefore, there is an urgent need to design a steel container for low- and intermediate-level radioactive metal waste to solve the aforementioned problems. Utility Model Content

[0004] To address the aforementioned technical problems, this utility model provides a steel box for replacing pressure pipelines in heavy water reactors, comprising a box body and a box cover. The box body and box cover are connected and fixed by a disassembly assembly. The box body includes a box frame, and the box frame includes two lower crossbeams. Placement holes are provided on the lower crossbeams, and a fork groove is welded between the placement holes on the two lower crossbeams. The fork groove is a rectangular tube welded from thin steel plates.

[0005] Furthermore, the lower crossbeam includes a lower crossbeam web and a lower crossbeam flange, the lower crossbeam flanges are disposed on both sides of the lower crossbeam web, and the lower crossbeam is made of channel steel.

[0006] Furthermore, end connecting plates are welded to both ends of the lower crossbeam, side connecting plates are welded to the sides of the lower crossbeam, and the side connecting plates are also welded to the end connecting plates. A support plate, parallel to the end connecting plates, is welded between the flanges of the lower crossbeam, and the support plate is also welded to the side connecting plates.

[0007] Furthermore, the box frame also includes box columns, upper crossbeams, upper longitudinal beams and lower longitudinal beams. The box columns are welded above the lower crossbeams and end connecting plates. The lower longitudinal beams are welded to one side of the lower crossbeam flanges and end connecting plates. The upper crossbeams and upper longitudinal beam flanges are respectively welded to the box columns.

[0008] Furthermore, the support plate is located below the box column.

[0009] Furthermore, the enclosure also includes long side plates, short side plates, and a bottom plate. The long and short side plates are welded to the sides of the enclosure frame, and the bottom plate is welded to the bottom surface of the enclosure frame. The bottom plate is also welded to the fork groove. The enclosure is constructed by welding the long side plates, short side plates, and bottom plate to the enclosure frame as a single unit, thereby improving the load-bearing capacity of the steel enclosure. The thickness of the long side plates is greater than that of the short side plates. The bottom plate is made of thin steel plate and serves as the main load-bearing component of the steel enclosure.

[0010] Furthermore, the housing also includes a first reinforcing plate, which is located at the welding point between the lower crossbeam web and the lower longitudinal beam. The first reinforcing plate is welded to the lower crossbeam web, the lower longitudinal beam, and the bottom plate. The welding surface of the first reinforcing plate to the lower longitudinal beam is successively larger than the welding surface to the lower crossbeam web and the welding surface to the bottom plate.

[0011] Furthermore, the enclosure also includes a second reinforcing plate, which is disposed above the end connecting plate. The second reinforcing plate is welded to the end connecting plate and the enclosure column, and the welding surface of the second reinforcing plate to the enclosure column is larger than the welding surface to the end connecting plate.

[0012] Furthermore, the enclosure also includes a third reinforcing plate, which is disposed on one side of the side connecting plate and is parallel to the web of the lower crossbeam. The third reinforcing plate is also welded to the wing plate of the lower crossbeam and the uprights of the enclosure.

[0013] Preferably, the box body further includes a first transverse rib and a first longitudinal rib, both of which are welded to the bottom plate. The first transverse rib is also welded to the lower longitudinal beam, the first longitudinal rib, or the fork groove. The lower longitudinal beam is also welded to the lower transverse beam web and the first transverse rib.

[0014] Furthermore, the fork slot includes a fork slot body and a fork slot end plate. The fork slot body is provided with a fork slot opening, and the fork slot end plate is provided with a connection port that matches the fork slot opening. The fork slot opening is welded inside the connection port, and the fork slot end plate is also welded to the lower crossbeam wing plate.

[0015] This utility model has the following beneficial effects:

[0016] (1) The lower crossbeam of this utility model is made of channel steel, the box column is made of square tube, and the upper crossbeam and upper longitudinal beam are made of rectangular tube. The box frame is welded from channel steel, square tube and rectangular tube, which makes the overall weight of the steel box lighter, the amount of welding construction less, and easier to manufacture.

[0017] (2) The lower crossbeam of this utility model is provided with a placement hole, which facilitates the use of forklifts for handling and is suitable for places where the lifting height is limited;

[0018] (3) In this utility model, a placement hole is provided in the web of the lower crossbeam. The wing plate of the lower crossbeam is not damaged and is still continuous in length. The retention of the wing plate reduces the bending section modulus of the lower crossbeam by little and has little impact on the bending performance of the channel steel. The fork slot body and the fork slot end plate are welded at the placement hole of the lower crossbeam for local reinforcement. The bending performance after reinforcement is stronger and the compressive performance is comparable.

[0019] (4) In this utility model, by welding an end connecting plate, a side connecting plate, a support plate, a first reinforcing plate, a second reinforcing plate and a third reinforcing plate to the lower crossbeam, the structural strength of the bottom corner of the steel box is high, and even if it falls during transportation, the waste inside the box will not be exposed.

[0020] (5) The cover of the box in this utility model is provided with four baffles, which are slightly thinner than the thickness of the bottom pad. When the steel boxes are stacked, the position of the four baffles can limit the corresponding bottom pad of the upper steel box to a small range, prevent excessive offset when the steel boxes are stacked, and ensure stable stacking of the steel boxes.

[0021] (6) The thickness of the long side plate in this utility model is greater than that of the short side plate. For the design of pressure pipelines, the overall weight of the steel box can be further reduced. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0023] Figure 2 This is a schematic diagram of the lower crossbeam in this utility model.

[0024] Figure 3 This is a schematic diagram of the bottom corner portion of this utility model.

[0025] Figure 4 This is a schematic diagram of the box body in this utility model.

[0026] Figure 5 This is a schematic diagram of the bottom of the box in this utility model.

[0027] Figure 6 This is a schematic diagram of the lug base in this utility model.

[0028] Figure 7This is a schematic diagram of a lifting lug base with a lifting ring in this utility model.

[0029] Figure 8 This is a partial schematic diagram of the welding between the lifting lug and the sealing groove plate in this utility model.

[0030] Figure 9 This is a partial schematic diagram of the box cover in this utility model.

[0031] Figure 10 This is a schematic diagram of the interior of the box cover in this utility model.

[0032] Figure 11 This is a schematic diagram of the first frame plate in this utility model.

[0033] Figure 12 This is a schematic diagram of the second frame plate in this utility model.

[0034] Figure 13 This is a schematic diagram of the disassembly and assembly components in this utility model.

[0035] Figure 14 This is a partial schematic diagram of the box cover and the lifting lug when the box body and the box cover are connected and fixed in this utility model. Detailed Implementation

[0036] The technical solution of this utility model will be further described in detail below with reference to specific embodiments. However, this embodiment is not intended to limit this utility model. Any similar structure or similar variation of this utility model should be included in the protection scope of this utility model. The commas in this utility model all indicate the relationship between and. The English letters in this utility model are case-sensitive.

[0037] like Figure 1 As shown, this utility model provides a steel box for replacing pressure pipelines in heavy water reactors, including a box body 1 and a box cover 2. The box body 1 and the box cover 2 are connected and fixed by a disassembly assembly 5. The box body 1 includes a box frame, and the box frame includes two lower crossbeams 13. The lower crossbeams 13 are provided with placement holes 130. A fork groove 131 is welded between the placement holes on the two lower crossbeams 13. The fork groove 131 facilitates forklift handling and is suitable for places where lifting height is limited. The fork groove 131 is a rectangular tube welded from thin steel plates.

[0038] like Figure 2-3As shown, the lower crossbeam 13 is made of channel steel. The lower crossbeam 13 includes a lower crossbeam web 135 and a lower crossbeam flange 136. The lower crossbeam flange 136 is disposed on both sides of the lower crossbeam web 135. End connecting plates 132 are welded to both ends of the lower crossbeam 13. Side connecting plates 133 are welded to the sides of the lower crossbeam 13, and the side connecting plates 133 are also welded to the end connecting plates 132. A support plate 134, which is parallel to the end connecting plates 132, is welded between the lower crossbeam flanges 136. The support plate 134 is also welded to the side connecting plates 133.

[0039] like Figure 3-5 As shown, the box frame also includes box columns 11, upper crossbeams 12, upper longitudinal beams 14, and lower longitudinal beams 15. The box columns 11 are welded above the lower crossbeam flange 136 and end connecting plate 132. The lower longitudinal beam 15 is welded to one side of the lower crossbeam flange 136 and end connecting plate 132. The upper crossbeams 12 and upper longitudinal beams 14 are respectively welded to the box columns 11. Preferably, the box columns 11 are made of square tubing, and the upper crossbeams 12 and upper longitudinal beams 14 are made of rectangular tubing. The support plate 134 is located below the box columns 11. The box body 1 also includes a long side plate 16, a short side plate 18, and a bottom plate 17. The long side plate 16 and the short side plate 18 are welded to the sides of the box body frame, and the bottom plate 17 is welded to the bottom surface of the box body frame. The bottom plate 17 is also welded to the fork groove 131. The box body 1 is welded to the box body frame by the long side plate 16, the short side plate 18, and the bottom plate 17, thereby improving the load-bearing capacity of the steel box. Since it is a replacement of pressure pipeline, the pipe area in the vertical side direction is small (the pipe cross-section is hollow), while the pipe area in the vertical end face direction is large (the projection is a rectangular surface). Therefore, the thickness of the long side plate 16 is greater than the thickness of the short side plate 18 to reduce the overall weight of the steel box. The bottom plate 17 is made of thin steel plate and serves as the main load-bearing component of the steel box. The long side plate 16 and the short side plate 18 can be made of corrugated plate or ordinary steel plate; the upper crossbeam 12, the lower crossbeam 13, the upper longitudinal beam 14, and the lower longitudinal beam 15 are made of rectangular tubes.

[0040] The housing 1 also includes a first reinforcing plate 19, which is located at the welding point between the lower crossbeam web 135 and the lower longitudinal beam 15. The first reinforcing plate 19 is welded to the lower crossbeam web 135, the lower longitudinal beam 15, and the bottom plate 17. The welding surface of the first reinforcing plate 19 to the lower longitudinal beam 15 is successively larger than the welding surface to the lower crossbeam web 135 and the welding surface to the bottom plate 17.

[0041] The box body 1 also includes a second reinforcing plate 10, which is disposed above the end connecting plate 132. The second reinforcing plate 10 is welded to the end connecting plate 132 and the box body column 11. The welding surface of the second reinforcing plate 10 to the box body column 11 is larger than the welding surface to the end connecting plate 132. A bottom pad 111 is provided at the bottom of the lower crossbeam wing plate 136, the lower longitudinal beam 15, the end connecting plate 132, the side connecting plate 133, and the first reinforcing plate 19. The bottom pad 111 is welded to the lower crossbeam wing plate 136, the lower longitudinal beam 15, the end connecting plate 132, the side connecting plate 133, and the first reinforcing plate 19, respectively. By welding the end connecting plate 132, the side connecting plate 133, the support plate 134, the first reinforcing plate 19, and the second reinforcing plate 10 to the lower crossbeam 13, the structural strength at the bottom corner of the steel box is high, and even if it falls during transportation, the waste inside the box will not be exposed.

[0042] The enclosure also includes a third reinforcing plate 100, which is disposed on one side of the side connecting plate and is parallel to the lower crossbeam web 135. The third reinforcing plate is also welded to the lower crossbeam wing plate 136 and the enclosure column.

[0043] Preferably, the box body 1 further includes a first transverse rib 101 and a first longitudinal rib 102, both of which are welded to the bottom plate 17. The first transverse rib 101 is also welded to the lower longitudinal beam 15, the first longitudinal rib 102, or the fork groove 131; the lower longitudinal beam 15 is also welded to the lower transverse beam web 135 and the first transverse rib 101. The first transverse rib 101 and the first longitudinal rib 102 are made of rectangular tubing.

[0044] The fork slot 131 includes a fork slot body 1311 and a fork slot end plate 1312. The fork slot body 1311 is provided with a fork slot opening 1313, and the fork slot end plate 1312 is provided with a connection port that matches the fork slot opening 1313. The fork slot opening 1313 is welded inside the connection port, and the fork slot end plate 1312 is also welded to the lower crossbeam wing plate 136.

[0045] Specifically, a placement hole is provided on the web plate 135 of the crossbeam. The fork slot end plate 1312 is also welded to the lower crossbeam flange 136. The lower crossbeam 13 is mainly subjected to compression and bending. The hole in the lower crossbeam web plate 135 is not damaged. Since the upper and lower lower crossbeam flanges 136 are not damaged and still have continuity in length, and the retention of the flanges does not reduce the bending section modulus of the lower crossbeam by much, the impact on the bending performance of the channel steel is small. Local reinforcement is carried out by welding the fork slot body and the fork slot end plate at the placement hole of the lower crossbeam. The bending performance after reinforcement is stronger and the compressive performance is comparable. If the lower crossbeam web plate 135 and the lower crossbeam flange 136 are damaged, the bending performance and overall rigidity of the lower crossbeam will be affected, and it will be easy to deform during welding. Moreover, the welded part is the main load-bearing part of bending, so the weld needs to be enlarged, increasing the amount of welding work. In addition, opening a hole at 135 on the lower crossbeam web is relatively simple to process compared to opening holes on the flange and web together. The rigidity after opening the hole is better and it is not easy to change during welding. The welded parts are all thin-walled plates with a wall thickness less than the average thickness of the flange. They are not the main load-bearing parts, so a smaller amount of welding work can be used.

[0046] like Figure 4 As shown, the box body 1 is provided with a lifting lug 3, and the lifting lug 3 is provided with a lifting ring 30. The lifting lug 3 is configured to form a stacking support surface with the box cover 2 when the steel boxes are stacked.

[0047] like Figure 6-7As shown, the lifting lug 3 includes a base 31 and a boss 32. The boss 32 is disposed above the base 31, and the base 31 and the boss 32 form a cavity 33 to reduce unnecessary weight. The boss 32 includes a first boss portion 321, a second boss portion 322, and a third boss portion 323. The first boss portion 321 and the third boss portion 323 are respectively located on both sides of the second boss portion 322. The first boss portion 321 is rectangular, and a first arc-shaped connecting surface 320 is provided between the first boss portion 321 and the second boss portion 322. A second arc-shaped connecting surface 324 is provided between the third boss portion 323 and the second boss portion 322. The third boss portion 323 has an inclined surface 3231. Since the lifting ring 30 needs space to rotate, a first notch 325 is provided between the third boss portion 323 and the second boss portion 322. An arc-shaped groove 311 is provided on the base 31 of the lifting lug 3. The second protrusion 322 has an inclined surface 3221, and the inclined surface 3221 has a lifting ring hole 34 for accommodating the lifting ring. The lifting ring 30 is clearance-fitted with the lifting ring hole 34, and the lifting ring 30 can rotate within the lifting ring hole 34. By placing the lifting ring 30 on the inclined surface 3221, the tension direction of the lifting ring is oriented towards the center of the container, avoiding lateral additional force on the lifting ring during hoisting. Compared with welding the lifting ring to the container column, welding it to the lifting lug 3 results in less stress concentration and is safer and more reliable. The lifting lug 3 is welded to the end face of the container column 11, which can reduce the width of the container 1 and facilitate the transportation of waste through the passageway door of the nuclear power plant site. The upper crossbeam 12 and the upper longitudinal beam 14 are provided with sealing groove plates 4, and the sealing groove plates 4 are provided with slots 41.

[0048] like Figure 8 As shown, the lifting lug 3 is welded to the sealing groove plate 4 as a whole, the groove 41 and the arc groove 311 form a complete sealing groove, the sealing groove is provided with a sealing strip, and the highest horizontal plane of the sealing groove is flush with the horizontal plane of the base 31.

[0049] like Figure 9-12As shown, the box cover 2 includes a cover plate 21, a first frame plate 22, and a second frame plate 23. The first frame plate 22 is welded to the long side of the cover plate 21, and the second frame plate 23 is welded to the short side of the cover plate 21. The first frame plate 22 is L-shaped, and the top of the long side of the L-shape of the first frame plate 22 is welded to the cover plate 21. The opening of the L-shape of the first frame plate faces outward. The second frame plate 23 includes a second frame plate body 231 and a frame plate post 232. The second frame plate body 231 is L-shaped, and the L-shape of the second frame plate body 231 is long... The top edge is welded to the cover plate 21. The L-shaped opening of the second frame plate body faces outward. The frame plate column 232 is set on the short side of the L-shape of the second frame plate body 231 and located at both ends of the second frame plate body 231 (second frame plate). The sealing groove is in seamless contact with the first frame plate 22 and the second frame plate 23 of the box cover 2, so that the box cover and the box body are well connected. It can make the sealing ring be evenly compressed, and ensure the sealing performance while reducing the number of disassembly and assembly components. The reduction of the number of disassembly and assembly components can also shorten the operation time during box packing. The first frame plate 22 and the second frame plate 23 are provided with a first connecting block 24. The first connecting block 24 is welded with a first bolt seat 25. The first bolt seat 25 is provided with a first opening 251. The first opening 251 is U-shaped. The number and position of the first bolt seats 25 on the first frame plate 22 and the second frame plate 23 can be determined according to the size and / or weight of the steel box to ensure that the box body and the box cover can be connected and fixed. Since the length of the first frame plate 22 is greater than the length of the second frame plate 23, the first bolt seats 25 on the first frame plate 22 are provided with a first bolt seat 25. The number of U-shaped rings 26 and second connecting blocks 27 are welded to the second frame plate 23 of the box cover 2. The second connecting block 27 is placed inside the ring of the U-shaped ring 26 and welded to the U-shaped ring 26. The welding surface of the U-shaped ring 26 is increased by the second connecting block 27 to improve stability. The U-shaped ring 26 is used for lifting the box cover itself. The number of U-shaped rings 26 can be determined according to the size and / or weight of the steel box. The same number of U-shaped rings 26 are provided on the two second frame plates 23. The U-shaped rings 26 need to be symmetrically arranged to ensure the stability of lifting.

[0050] The box cover 2 is provided with four baffles 28, which are slightly thinner than the bottom pad 111. When the steel boxes are stacked, the position of the four baffles 28 can limit the corresponding bottom pad 111 of the upper steel box to a small range, preventing excessive offset when the steel boxes are stacked and ensuring stable stacking of the steel boxes.

[0051] The cover plate 21 is a thin steel plate, and its thickness is sufficient to meet the thickness of the sealing panel, thereby reducing the overall weight of the steel box.

[0052] like Figure 13As shown, both the upper crossbeam 12 and the upper longitudinal beam 14 are welded with disassembly and assembly components 5. The disassembly and assembly components 5 are used for quick disassembly and assembly of the housing 1 and the housing cover 2; the disassembly and assembly components 5 are correspondingly arranged with the first bolt seat 25; the disassembly and assembly components 5 include a second bolt seat 51, a bolt 52, a bolt shaft 53, a first nut 54, a second nut 55, and a washer 56. The bolt 52 is configured to rotate about the bolt shaft 53 toward the first opening 251 of the first bolt seat 25; the second bolt seat 51 has a second opening 511, which is U-shaped, and an L-shaped opening 510 is provided at the bottom of the U-shape of the second opening 511. The L-shaped opening 510 is connected to the upper crossbeam 12. Beam 12 / upper longitudinal beam 14 are welded together. The two ends of the U-shaped second opening 510 are provided with first connecting holes. The bolt shaft 53 is placed in the first connecting hole. One end of the bolt 52 is provided with a second connecting hole. The bolt shaft 53 is placed in the first connecting hole and the second connecting hole. The two ends of the bolt shaft 53 are fixed by the second nut 55. The other end of the bolt 52 is provided with an external thread for connecting with the first nut 54. The first thread near the end of the bolt is provided with a second notch to prevent the first nut 54 from coming off the bolt. The washer is placed between the second bolt seat 51 and the first nut 54.

[0053] The second bolt seat 51 has a chamfer at one end near the first nut, which can reduce the radius of the bolt 52 when it rotates. The first nut 54 only needs a small amount of loosening to rotate and disengage from the cover 2. When the bolt 52 returns to its original position, the first nut 54 only needs a small amount of tightening to press the cover 2. This achieves quick assembly and disassembly.

[0054] The inner side of the lid 2 is provided with a second horizontal rib 201 and a second vertical rib 202. The horizontal ribs 201 and the vertical ribs 202 are intersected to form a grid-like skeleton. When the lid 2 is subjected to pressure from above, the second horizontal ribs and the second vertical ribs can evenly transfer the force to the edges or supporting structures, preventing the lid from deforming or breaking due to excessive local stress. At the same time, the crisscrossing skeleton can significantly improve the overall rigidity of the lid and reduce vibration or warping during use. The second horizontal rib 201 and the second vertical rib 202 are made of square tubing.

[0055] like Figure 14As shown, when the box body 1 is connected and fixed to the box cover 2, the horizontal planes at the ends of the frame plate column 232, the first boss 321, the second boss 322, and the third boss 323 are all flush with the cover plate 21. When the steel boxes are stacked, the boss 32 of the lifting lug 3, the frame plate column 232, and the cover plate 21 form the support surface for stacking the steel boxes. Part of the stacking load acts directly on the end of the boss; another part acts on the cover plate 21. This part of the load is also transmitted to the lifting lug 3. The stacking load is ultimately transmitted through the lifting lug 3 to the box body column 11 below the lifting lug 3, and then to the ground. This structure has the characteristics of high strength, good rigidity, and light weight. No additional reinforcement is required at the load application point. If the stacking load acts on the upper crossbeam, upper longitudinal beam, or other low-strength positions, additional reinforcement is required at the load application point.

[0056] In use, after loosening the first nut 54 on all bolts 52, rotate bolts 52 toward the second opening 511. At this time, the box body 1 and the box cover 2 are in a non-fixed state. Use the U-shaped ring 26 to lift the box cover 2 away, load the waste into the box body 1, lift the box cover 2 back, rotate bolts 52 toward the first opening 251, tighten the first nut 54, connect and fix the box body 1 and the box cover 2, and then use the lifting ring 30 to lift the entire steel box away.

[0057] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

Claims

1. A steel box for replacing pressure pipelines in heavy water reactors, comprising a box body and a box cover, wherein the box body and the box cover are connected and fixed by a disassembly assembly, characterized in that, The box body includes a box frame, the box frame includes two lower crossbeams, the lower crossbeams are provided with placement holes, and a fork groove is welded between the placement holes on the two lower crossbeams.

2. A steel box for replacing pressure pipelines in heavy water reactors according to claim 1, characterized in that, The lower crossbeam includes a lower crossbeam web and a lower crossbeam flange, with the lower crossbeam flanges disposed on both sides of the lower crossbeam web.

3. A steel box for replacing pressure pipelines in heavy water reactors according to claim 2, characterized in that, End connecting plates are welded to both ends of the lower crossbeam, and side connecting plates are welded to the sides of the lower crossbeam. The side connecting plates are also welded to the end connecting plates. A support plate, parallel to the end connecting plates, is welded between the flanges of the lower crossbeam. The support plate is also welded to the side connecting plates.

4. A steel box for replacing pressure pipelines in heavy water reactors according to claim 3, characterized in that, The box frame also includes box columns, upper crossbeams, upper longitudinal beams and lower longitudinal beams. The box columns are welded above the lower crossbeam flange and end connecting plate. The lower longitudinal beams are welded to one side of the lower crossbeam web and end connecting plate. The upper crossbeams and upper longitudinal beams are welded to the box columns respectively.

5. A steel box for replacing pressure pipelines in heavy water reactors according to claim 4, characterized in that, The support plate is located below the upright column of the box body.

6. A steel box for replacing pressure pipelines in heavy water reactors according to claim 4, characterized in that, The enclosure also includes a long side plate, a short side plate, and a bottom plate. The long side plate and the short side plate are respectively welded to the sides of the enclosure frame, and the bottom plate is welded to the bottom surface of the enclosure frame. The bottom plate is also welded to the fork groove. The thickness of the long side plate is greater than the thickness of the short side plate.

7. A steel box for replacing pressure pipelines in heavy water reactors according to claim 6, characterized in that, The housing also includes a first reinforcing plate, which is located at the welding point between the lower crossbeam web and the lower longitudinal beam. The first reinforcing plate is welded to the lower crossbeam web, the lower longitudinal beam, and the bottom plate. The welding surface of the first reinforcing plate to the lower longitudinal beam is successively larger than the welding surface to the lower crossbeam web and the welding surface to the bottom plate.

8. A steel box for replacing pressure pipelines in heavy water reactors according to claim 4, characterized in that, The enclosure also includes a second reinforcing plate, which is disposed above the end connecting plate. The second reinforcing plate is welded to the end connecting plate and the enclosure column, and the welding surface of the second reinforcing plate to the enclosure column is larger than the welding surface to the end connecting plate.

9. A steel box for replacing pressure pipelines in heavy water reactors according to claim 4, characterized in that, The enclosure also includes a third reinforcing plate, which is disposed on one side of the side connecting plate and is parallel to the web of the lower crossbeam. The third reinforcing plate is also welded to the wing plate of the lower crossbeam and the column of the enclosure.

10. A steel box for replacing pressure pipelines in heavy water reactors according to claim 4, characterized in that, The fork slot includes a fork slot body and a fork slot end plate. The fork slot body is provided with a fork slot opening, and the fork slot end plate is provided with a connection port that matches the fork slot opening. The fork slot opening is welded inside the connection port, and the fork slot end plate is also welded to the lower crossbeam wing plate.

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