Storage device for heavy water reactor spent fuel and method of installing the same

Abstract

This disclosure pertains to the field of nuclear power technology, specifically relating to a storage device for spent fuel in heavy water reactors and its installation method. This disclosure breaks down the overall processing of the storage cylinder into multiple segments, including the upper structure, multi-section cylinder, and lower structure. Processing is performed using the bottom ring plate of the support as a reference surface, reducing the manufacturing difficulty of each segment, improving the processing accuracy of each segment, and further controlling the processing accuracy of each segment to exceed the overall processing accuracy requirements of the storage cylinder. This allows for allowances to accommodate minor deformations after welding of each segment, effectively ensuring the overall processing accuracy of the storage cylinder. During assembly, this disclosure uses the upper plate as a reference surface, ensuring that the levelness of the bottom plate surface and the concrete pouring process no longer affect the leveling of the storage cylinder, effectively overcoming errors that gradually accumulate from bottom to top. This ensures the overall installation accuracy of the storage cylinder and meets the requirements for spent fuel loading.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power technology, specifically relating to a storage device for spent fuel in heavy water reactors and its installation method. Background Technology

[0002] The dry storage module for spent fuel in a heavy water reactor contains multiple vertical storage cylinders, which are the core equipment of the module. The leveling process during cylinder installation is crucial; any defects in leveling will severely impact the safety of remote mechanical loading. For example, if the spent fuel basket deviates from its axis, repeated collisions with the cylinder wall during descent will cause severe deformation, making retrieval difficult. Alternatively, collisions with the cylinder wall or even tipping over can damage both the storage cylinder and the spent fuel basket, rendering them unusable.

[0003] The industry-standard MACSTOR type storage module uses a top plate to fix the storage cylinder. The leveling process for installing the storage cylinder only requires leveling the surface of the top plate and the upper end of the storage cylinder. The bottom of the storage cylinder is a free end, which can be thermally expanded and contracted vertically.

[0004] If the storage cylinder is fixed from the bottom plate instead of the top plate, the installation sequence will change to bottom-up. Errors in each step of the installation process will accumulate gradually from bottom to top, making control more complex. Furthermore, in engineering practice, defects in the storage cylinder installation process only become apparent in the last few steps, leading to complete rework and a significant waste of manpower and resources. Therefore, it is evident that changing the storage cylinder to a bottom-fixed design significantly increases installation difficulty, necessitating the overcoming of numerous technical challenges related to installation accuracy and efficiency. Summary of the Invention

[0005] To overcome the problems existing in related technologies, a storage device for spent fuel from heavy water reactors and its installation method are provided.

[0006] According to one aspect of the present disclosure, a storage device for spent fuel in a heavy water reactor is provided. The storage device includes: a storage cylinder, a support, and pre-embedded components. The storage device is fixedly installed on a base plate within a storage module, and the top plate of the storage module does not support the storage device. The storage cylinder is assembled in the order of an upper structure, a multi-section cylinder, and a lower structure.

[0007] The pre-embedded components include: an upper plate, a lower plate, and multiple anchor bolts; the lower plate is embedded in the bottom plate of the storage module, the upper plate is embedded and fixed on the surface of the bottom plate, and the upper surface of the upper plate is exposed on the bottom plate, and the flatness of the upper surface of the upper plate does not exceed 5mm;

[0008] The support is a tubular structure, which is sleeved and fixed to the outer wall of the storage cylinder; the bottom end of the support is provided with a ring plate, the outer edge of the ring plate extends radially outward, and the inner edge of the ring plate extends radially inward; the flatness of the lower surface of the ring plate does not exceed 3mm.

[0009] The flatness of the lower surface of the lower structure is no more than 3 mm compared to the lower surface of the ring plate; the verticality of each section of the cylinder is no more than 7 mm compared to the lower surface of the ring plate; the overall straightness of the assembled multi-section cylinder is no more than 6 mm, and the straightness of the cylinder within every 3 meters of the assembled multi-section cylinder is no more than 3 mm; the verticality of the upper structure is no more than 10 mm compared to the lower surface of the ring plate.

[0010] The bottom end of the storage cylinder is suspended above the upper surface of the upper plate. The ring plate is installed on the upper surface of the upper plate. The outer wall of the support has multiple lugs extending radially outward. Each anchor bolt is fixedly connected to the lower plate, the upper plate, the ring plate, and one lug. With the upper surface of the upper plate as the reference plane, the installation level of the lower surface of the ring plate does not exceed 2mm, and the verticality of the centerline of the storage cylinder does not exceed 8mm along its entire length.

[0011] In one possible implementation, the storage device further includes multiple positioning pins and positioning pins. The multiple positioning pins and positioning pins are disposed on the upper surface of the top plate of the storage module. The multiple positioning pins are evenly distributed around the center of the storage cylinder. The positioning pins are disposed near the storage cylinder and the positioning pins. The flatness of the upper surface is allowed to have a deviation of ±1mm. The horizontal tolerance of each positioning pin does not exceed 3mm. The upper surface of each positioning pin is the highest point of the module top. The positioning pins are used for the alignment and positioning of the adapter and the storage cylinder.

[0012] According to another aspect of the present disclosure, an installation method for a heavy water reactor spent fuel storage device is provided, the method being implemented based on the above-described heavy water reactor spent fuel storage device, the method comprising:

[0013] Step 1: The lower plate is positioned and installed on the padding layer of the storage module using expansion bolts, and the level of the lower plate is adjusted to meet the preset requirements.

[0014] Step 2: Weld multiple first nuts at preset positions on the upper surface of the lower plate, ensuring that the horizontal deviation between each first nut and the center of the lower plate does not exceed 1mm. Then, install and connect the lower end of each anchor bolt to a first nut to form a pre-fixed bolt group, ensuring that the horizontal deviation between the top of each anchor bolt and the center of the lower plate does not exceed 2mm after installation.

[0015] Step 3: After installing a second nut on each bolt, the upper plate with arrayed bolt holes is axially fitted into the pre-fixed bolt group. Each anchor bolt is inserted into a bolt hole, so that the upper plate is supported on each second nut. Rotating any one or more second nuts can adjust the level of the upper plate. When the level of the upper plate meets the preset requirements, each second nut is spot welded to the lower surface of the upper plate.

[0016] Step 4: After the pre-embedded components are installed, pour the base slab concrete. After the base slab concrete is poured, the flatness of the upper slab should be less than 5mm, and the installation tolerance of the exposed length of the anchor bolts should be 0~1mm.

[0017] In one possible implementation, in step one, the levelness of the lower plate is adjusted by adjusting the number of stainless steel shims between the lower plate and the pad.

[0018] In one possible implementation, in step two, the upper surface of the lower plate is provided with multiple positioning areas, and the marking size of each positioning area is consistent with the outer diameter of the first nut, and each first nut is welded and fixed in one positioning area.

[0019] In one possible implementation, during step three, when installing anchor bolts on the upper surface of the lower plate, the position of each anchor bolt is adjusted by using a simulation component to constrain it before installing the upper plate. After the upper plate is installed, the simulation component is removed. The simulation component has the same dimensions and bolt hole layout as the upper plate and is made of lightweight material.

[0020] In one possible implementation, the lower layer of reinforcing bars in the base plate is tied before the anchor bolts are installed, and the upper layer of reinforcing bars in the base plate is tied after the anchor bolts are installed.

[0021] In one possible implementation, thermally sprayed zinc is used for corrosion protection on the upper surface of the upper plate and the lower surface of the lower plate, with a coating thickness of at least 350 μm.

[0022] In one possible implementation, after the storage cylinder is in place and fixed, the support is sprayed with zinc, and grout is poured into the first cavity formed between the bottom of the storage cylinder, the inner wall of the support, and the upper plate until it is 10cm away from the bottom of the storage cylinder.

[0023] A stiffening plate is provided on both sides of each lug of the support to connect the lug to the ring plate. The stiffening plate and the folding plate cooperate to form a second cavity. Grout is injected into the second cavity through the through hole reserved in the folding plate to fill the second cavity.

[0024] Each anchor bolt is secured by a nut and bolt at the point where it protrudes from the lug, and is welded together. A sleeve is installed around the outside of the nut and bolt on the upper surface of the lug, and grout is poured into the sleeve to cover the nut and bolt inside the sleeve.

[0025] In one possible implementation, multiple discharge ports are provided on the top plate of the storage module, each discharge port facing a storage cylinder. The storage device also includes a support cylinder and a water-blocking cylinder. The support cylinder surrounds the inner wall of the corresponding discharge port to support it. The water-blocking cylinder surrounds the inner wall of the upper opening of the discharge port and is welded to the support cylinder below. The upper edge of the water-blocking cylinder extends above the upper edge of the discharge port to prevent water accumulated on the outer surface of the top plate from flowing into the discharge port. The support cylinder and the water-blocking cylinder are installed using the following steps:

[0026] Step 5: After the top plate support scaffolding and bottom formwork are installed, measure the preset gap between the storage cylinder and the support cylinder. Nail steel nails of the same length as the preset gap symmetrically on the bottom formwork along the outer wall of the storage cylinder to locate the inner diameter of the support cylinder. Reinforce the outer wall of the storage cylinder with extruded polystyrene boards of the same thickness as the preset gap. Hoist the first and second halves of the support cylinder to the top of the storage cylinder, assemble and fasten the first and second halves into a whole support cylinder, and tighten the bolts between the first and second halves.

[0027] Step 6: The gap error between the support cylinder and the storage cylinder shall not exceed 0.5mm. The installation height of the support cylinder shall be adjusted based on the horizontal plane of the water baffle ring plate. After the support cylinder is positioned, shims shall be evenly inserted between the water baffle and the storage cylinder. After the water baffle and the support cylinder are circumferentially welded together, the elevation of the water baffle ring plate shall be checked and adjusted again to the design value, and then the shims shall be removed.

[0028] The beneficial effects of this disclosure are as follows: This disclosure breaks down the overall processing of the storage cylinder into multiple segments, including the upper structure, multi-section cylinder, and lower structure. Processing is performed using the bottom ring plate of the support as the reference surface, reducing the manufacturing difficulty of each segment, improving the processing accuracy of each segment, and further controlling the processing accuracy of each segment to exceed the overall processing accuracy requirements of the storage cylinder. This provides a margin for minor deformations after welding of each segment, effectively ensuring the overall processing accuracy of the storage cylinder. During assembly, this disclosure uses the upper plate as the reference surface, ensuring that the levelness of the bottom plate surface and the concrete pouring process no longer affect the leveling of the storage cylinder, effectively overcoming errors that gradually accumulate from bottom to top. This ensures the overall installation accuracy of the storage cylinder and meets the requirements for spent fuel loading. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of a storage device for spent fuel from a heavy water reactor, as shown in an embodiment of this disclosure.

[0030] Figure 2 This is a schematic diagram of a pre-embedded component shown in an embodiment of this disclosure.

[0031] Figure 3 This is a schematic diagram of a support shown in an embodiment of this disclosure.

[0032] In the picture:

[0033] 1. Storage cylinder; 2. Support; 3. Embedded components; 4. Support cylinder; 5. Water-blocking cylinder; 6. Shielding plug;

[0034] 7. Rain cover; 11. Upper structure; 12. Cylinder body; 13. Lower structure; 21. Lug;

[0035] 22. Ring plate; 31. Upper plate; 32. Lower plate; 33. Anchor bolt; 211. Stiffening plate; 212. Folding plate;

[0036] 213. Sleeve. Detailed Implementation

[0037] The present disclosure will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0038] Unless otherwise defined, the technical and scientific terms used in this disclosure have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains; the terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure; the term "comprising" and any variations thereof in this disclosure are intended to cover non-exclusive inclusion. Clearly, the embodiments described in this disclosure are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of this disclosure without inventive effort are within the scope of protection of this disclosure.

[0039] In this disclosure, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this disclosure. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0040] The storage device is fixedly installed inside the spent fuel storage module of the concrete structure. Figure 1 This is a schematic diagram of a storage device for spent fuel from a heavy water reactor, as shown in an embodiment of this disclosure. Figure 1 As shown, the storage device includes: a storage cylinder 1, a support 2, and a pre-embedded component 3; the storage device is fixedly installed on the base plate inside the storage module, and the top plate of the storage module no longer supports the storage device. The storage cylinder 1 is assembled in the order of upper structure 11, multi-section cylinder 12 (e.g., 3-section cylinder), and lower structure 13;

[0041] Figure 2 This is a schematic diagram of a pre-embedded component shown in an embodiment of this disclosure, such as... Figure 2As shown, the pre-embedded component 3 includes: an upper plate 31, a lower plate 32 and a plurality of anchor bolts 33; the lower plate 32 is embedded in the bottom plate of the storage module, the upper plate 31 is embedded and fixed on the surface of the bottom plate, and the upper surface of the upper plate 31 is exposed on the bottom plate, and the flatness of the upper surface of the upper plate 31 does not exceed 5mm.

[0042] Figure 3 This is a schematic diagram of a support according to an embodiment of the present disclosure, such as... Figure 3 As shown, the support 2 is a tubular structure, which is sleeved and fixed to the outer wall of the storage cylinder 1; the bottom end of the support 2 is provided with a ring plate 22, the outer edge of the ring plate 22 extends radially outward, and the inner edge of the ring plate 22 extends radially inward; the flatness of the lower surface of the ring plate 22 does not exceed 3mm; during the manufacturing process of the storage cylinder 1, the lower surface of the ring plate 22 is used as a reference surface, and the flatness of the lower surface of the lower structure 13 does not exceed 3mm compared to the lower surface of the ring plate 22; each section of the cylinder 12 is used to control the verticality and straightness of the storage cylinder 1 as a whole, and the verticality of each section of the cylinder 12 relative to the lower surface of the ring plate 22 does not exceed 7mm; the overall straightness of the assembled multi-section cylinder 12 does not exceed 6mm, and the straightness of the cylinder 12 within a 3-meter range after assembly does not exceed 3mm; the verticality of the upper structure 11 relative to the lower surface of the ring plate 22 does not exceed 10mm.

[0043] The bottom end of the storage cylinder 1 is suspended above the upper surface of the upper plate 31. The ring plate 22 is installed on the upper surface of the upper plate 31. The outer wall of the support 2 has a plurality of radially outwardly extending lugs 21. Each anchor bolt 33 is fixedly connected to the lower plate 32, the upper plate 31, the ring plate 22 and a lug 21 respectively. With the upper surface of the upper plate 31 as the reference plane, the installation level of the lower surface of the ring plate 22 does not exceed 2 mm, and the verticality of the center line of the storage cylinder 1 does not exceed 8 mm over its entire length.

[0044] This disclosure breaks down the overall processing of the storage cylinder into multiple segments, including the upper structure, multi-section cylinder, and lower structure. Using the bottom ring plate of the support as a reference surface, the processing of each segment is simplified, reducing manufacturing difficulty and improving processing accuracy. Furthermore, the processing accuracy of each segment is controlled to exceed the overall processing accuracy requirements of the storage cylinder, allowing for minor deformations after welding and effectively ensuring the overall processing accuracy of the storage cylinder. During assembly, the upper plate is used as a reference surface, ensuring that the levelness of the bottom plate surface and the concrete pouring process do not affect the leveling of the storage cylinder, effectively overcoming errors that accumulate gradually from bottom to top. This ensures the overall installation accuracy of the storage cylinder and meets the requirements for spent fuel loading.

[0045] In one possible implementation, the pre-embedded component is installed using the following steps:

[0046] Step 1: The lower plate is positioned and installed on the padding layer of the storage module using expansion bolts. The levelness of the lower plate is adjusted by adjusting the stainless steel shims between the lower plate and the padding layer.

[0047] Step two: The lower plate is provided with multiple positioning areas. The marking size of each positioning area can be consistent with the outer diameter of the first nut, which facilitates the positioning of each first nut during the welding process. Each first nut is welded and fixed in a positioning area, and the horizontal deviation between each first nut and the center of the lower plate does not exceed 1mm. Then, the lower end of each anchor bolt is installed and connected to a first nut to form a pre-fixed bolt group, so that the horizontal deviation between the top of each anchor bolt and the center of the lower plate does not exceed 2mm after installation.

[0048] Step 3: After installing a second nut on each bolt, the upper plate with arrayed bolt holes is axially fitted into the pre-fixed bolt group. Each anchor bolt is inserted into a bolt hole, so that the upper plate is mounted on each second nut. Rotating any one or more second nuts can adjust the level of the upper plate. When the upper plate is leveled to meet the preset requirements, each second nut is spot welded to the lower surface of the upper plate.

[0049] Step 4: After the pre-embedded components are installed, pour the base plate concrete. After the base plate concrete is poured, the flatness of the upper plate is less than 5mm, and the installation tolerance of the exposed length of the anchor bolts is 0~1mm.

[0050] The pre-embedded components disclosed herein adopt a split adjustable structure consisting of an upper plate, a lower plate, and anchor bolts. This allows construction personnel to easily adjust the leveling from bottom to top according to the actual working conditions of the base plate. This allows for flexible adaptation to different construction scenarios, improving the accuracy and efficiency of leveling. Furthermore, the leveling of the pre-embedded components precedes the pouring of the base plate, ensuring that the levelness of the base plate surface and the concrete pouring process have minimal impact on the leveling of the storage cylinder. This enables layer-by-layer adjustment of the levelness of the storage cylinder base and effectively fixes the storage cylinder after the base plate is poured, while simultaneously ensuring the leveling accuracy and installation firmness of the storage cylinder.

[0051] In one possible implementation, during step three, while installing the anchor bolts on the upper surface of the lower plate, the position of each anchor bolt is adjusted using a simulation component before installing the upper plate. After the upper plate is installed, the simulation component is removed. This ensures that after removing the simulation component, each bolt can be smoothly inserted into the corresponding bolt hole on the upper plate, and meets the installation requirement that the horizontal deviation between the top of each bolt and the center of the lower steel plate is less than or equal to 2mm. The simulation component has the same dimensions and bolt hole layout as the upper plate and is made of lightweight materials (such as aluminum or resin).

[0052] In one possible implementation, the lower layer of reinforcing bars in the base plate is tied before the anchor bolts are installed, and the upper layer of reinforcing bars in the base plate is tied after the anchor bolts are installed.

[0053] In one possible implementation, thermal spraying of zinc is applied to the upper surface of the upper plate and the lower surface of the lower plate for corrosion protection, with a coating thickness of at least 350 μm. After the storage cylinder is in place and fixed, the support is zinc-sprayed on the outside, and grout is poured into the first cavity formed between the bottom of the storage cylinder, the inner wall of the support, and the upper plate until it reaches 10 cm from the bottom of the storage cylinder.

[0054] like Figure 3 As shown, stiffening plates 211 are respectively provided on both sides of each lug 21 of the support 2, connecting the lug 21 to the ring plate 22. A folding plate 212 is covered at the opening on the side of the stiffening plate 211. The stiffening plate 211, the folding plate 212, the lug 21, and the ring plate 22 form a second cavity. Grout is injected into the second cavity through the through hole reserved in the folding plate 212 to fill the second cavity. Each anchor bolt 33 is fixed by a nut and a bolt at the position where it protrudes from the lug 21, and can be welded with a 2mm fillet weld to prevent loosening. A sleeve 213 is provided around the nut and bolt on the upper surface of the lug 21. Grout is injected into the sleeve to wrap the nut and bolt inside the sleeve. In the above manner, the lug, anchor bolt, ring plate, and the fixed connection position between the three are effectively wrapped, protected against corrosion, and supported.

[0055] In one possible implementation, see Figure 1 The storage module has multiple discharge ports on its top plate, each discharge port facing a storage cylinder 1. A shielding plug 6 is inserted into the top of the storage cylinder 1. The storage device also includes a support cylinder 4 and a water-blocking cylinder 5. The support cylinder 4 is arranged around the inner wall of the corresponding discharge port to support and fix the discharge port. The water-blocking cylinder 5 is arranged around the inner wall of the upper opening of the discharge port. The water-blocking cylinder 5 is welded to the support cylinder 4 below. The upper edge of the water-blocking cylinder 5 is higher than the upper edge of the discharge port to prevent water from the surface of the top plate from flowing into the discharge port. A rainproof cover 7 is provided at the upper end of the water-blocking cylinder 5. The support cylinder 4 and the water-blocking cylinder 5 are installed using the following steps.

[0056] Step 5: After the top plate support scaffolding and bottom formwork are installed, measure the preset gap (e.g., 20mm) between the storage cylinder and the support cylinder. Nail steel nails of the same length as the preset gap symmetrically on the bottom formwork along the outer wall of the storage cylinder to locate the inner diameter of the support cylinder. Reinforce the outer wall of the storage cylinder with 20mm thick extruded polystyrene boards. Hoist the first and second halves of the support cylinder to the top of the storage cylinder. Assemble and tighten the first and second halves into a whole support cylinder. Tighten the bolts between the first and second halves to ensure a tight joint.

[0057] Step Six: The gap error between the support cylinder and the storage cylinder should not exceed 0.5mm. The installation height of the support cylinder should be adjusted appropriately based on the horizontal plane of the baffle ring plate. After the support cylinder is precisely positioned and adjusted, shims are evenly inserted between the baffle cylinder and the storage cylinder to prevent welding deformation from reducing the distance between them. This ensures that the loading and unloading rings for the subsequent plug can be smoothly inserted. After the baffle cylinder and the support cylinder are circumferentially welded together, the elevation of the baffle ring plate is checked and adjusted again to the design value before removing the shims.

[0058] In this disclosure, although welding the water-blocking cylinder and the support cylinder at the factory is beneficial to control welding thermal deformation, the distance between the two storage cylinders is significantly reduced after dense storage. The top plate of the module is densely reinforced with steel bars. Installing the water-blocking cylinder first will further reduce the operating space for steel bar installation, making it inconvenient to tie the top plate steel bars and to transport the water-blocking cylinder and the support cylinder. Therefore, it is necessary to separate these two components and install them on site.

[0059] In one possible implementation, the storage device further includes multiple positioning pins and positioning pins. These positioning pins and pins are disposed on the upper surface of the top plate of the storage module. The positioning pins are evenly distributed around the center of the storage cylinder, and the positioning pins are positioned near the storage cylinder and the positioning pins. The positioning pins serve as a reference plane for the upper part of the storage cylinder where the shielded transport container is placed. The flatness of the upper surface of the positioning pins is allowed to deviate by ±1mm, and the horizontal tolerance of each positioning pin does not exceed 3mm. Multiple positioning pins are fixedly embedded around each storage cylinder on the upper surface of the top plate of the storage module. The upper surfaces of the concrete top plate and the water-retaining ring plate of the module cannot be higher than the upper surfaces of the positioning pins, ensuring that the upper surfaces of the positioning pins are the highest point of the module top, thus ensuring that the shielded transport container rests on the multiple positioning pins and is on the same horizontal plane.

[0060] The positioning pin is a positioning device for aligning the adapter with the storage cylinder, and it also determines whether the shielded transport container can ultimately be aligned with the storage cylinder, preventing the fuel from impacting the cylinder wall when it is lowered into the storage cylinder. To ensure the positioning pin is in place, a special tool for installing the positioning pin was fabricated on-site to facilitate determining the position of the positioning pin and ensure alignment with the storage cylinder.

[0061] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A storage device for spent fuel from heavy water reactors, characterized in that, The storage device includes: a storage cylinder, a support, and pre-embedded components; the storage device is fixedly installed on the base plate inside the storage module, and the top plate of the storage module does not support the storage device; the storage cylinder is assembled in the order of upper structure, multi-section cylinder, and lower structure; The pre-embedded components include: an upper plate, a lower plate, and multiple anchor bolts; the lower plate is embedded in the bottom plate of the storage module, the upper plate is embedded and fixed on the surface of the bottom plate, and the upper surface of the upper plate is exposed on the bottom plate, and the flatness of the upper surface of the upper plate does not exceed 5mm; The support is a tubular structure, which is sleeved and fixed to the outer wall of the storage cylinder; the bottom end of the support is provided with a ring plate, the outer edge of the ring plate extends radially outward, and the inner edge of the ring plate extends radially inward; the flatness of the lower surface of the ring plate does not exceed 3mm. The flatness of the lower surface of the lower structure is no more than 3 mm compared to the lower surface of the ring plate; the verticality of each section of the cylinder is no more than 7 mm compared to the lower surface of the ring plate; the overall straightness of the assembled multi-section cylinder is no more than 6 mm, and the straightness of the cylinder within every 3 meters of the assembled multi-section cylinder is no more than 3 mm; the verticality of the upper structure is no more than 10 mm compared to the lower surface of the ring plate. The bottom end of the storage cylinder is suspended above the upper surface of the upper plate. The ring plate is installed on the upper surface of the upper plate. The outer wall of the support has multiple lugs extending radially outward. Each anchor bolt is fixedly connected to the lower plate, the upper plate, the ring plate, and one lug. With the upper surface of the upper plate as the reference plane, the installation level of the lower surface of the ring plate does not exceed 2mm, and the verticality of the centerline of the storage cylinder does not exceed 8mm along its entire length.

2. The storage device for spent fuel from a heavy water reactor according to claim 1, characterized in that, The storage device also includes multiple positioning pins and positioning pins. The multiple positioning pins and positioning pins are set on the upper surface of the top plate of the storage module. The multiple positioning pins are evenly distributed around the center of the storage cylinder. The positioning pins are set near the storage cylinder and the positioning pins. The flatness of the upper surface is allowed to be ±1mm. The horizontal tolerance of each positioning pin does not exceed 3mm. The upper surface of each positioning pin is the highest point of the module top. The positioning pins are used for the alignment and positioning of the adapter and the storage cylinder.

3. An installation method for a spent fuel storage device for heavy water reactors, characterized in that, The method is implemented based on the storage device for spent fuel from a heavy water reactor as described in claim 1 or 2, and the method includes: Step 1: The lower plate is positioned and installed on the padding layer of the storage module using expansion bolts, and the level of the lower plate is adjusted to meet the preset requirements. Step 2: Weld multiple first nuts at preset positions on the upper surface of the lower plate, ensuring that the horizontal deviation between each first nut and the center of the lower plate does not exceed 1mm. Then, install and connect the lower end of each anchor bolt to a first nut to form a pre-fixed bolt group, ensuring that the horizontal deviation between the top of each anchor bolt and the center of the lower plate does not exceed 2mm after installation. Step 3: After installing a second nut on each bolt, the upper plate with arrayed bolt holes is axially fitted into the pre-fixed bolt group. Each anchor bolt is inserted into a bolt hole, so that the upper plate is supported on each second nut. Rotating any one or more second nuts can adjust the level of the upper plate. When the level of the upper plate meets the preset requirements, each second nut is spot welded to the lower surface of the upper plate. Step 4: After the pre-embedded components are installed, pour the base slab concrete. After the base slab concrete is poured, the flatness of the upper slab should be less than 5mm, and the installation tolerance of the exposed length of the anchor bolts should be 0~1mm.

4. The installation method for a spent fuel storage device for heavy water reactors according to claim 3, characterized in that, In step one, the levelness of the lower plate is adjusted by adjusting the number of stainless steel shims between the lower plate and the pad.

5. The installation method for a spent fuel storage device for heavy water reactors according to claim 3, characterized in that, In step two, multiple positioning areas are provided on the upper surface of the lower plate. The marking size of each positioning area is consistent with the outer diameter of the first nut, and each first nut is welded and fixed in one positioning area.

6. The installation method for a spent fuel storage device for heavy water reactors according to claim 3, characterized in that, In step three, during the installation of anchor bolts on the upper surface of the lower plate, the position of each anchor bolt is adjusted by using a simulation component to constrain it before installing the upper plate. After the upper plate is installed, the simulation component is removed. The simulation component has the same dimensions and bolt hole layout as the upper plate and is made of lightweight material.

7. The installation method for a spent fuel storage device for heavy water reactors according to claim 3, characterized in that, The lower layer of reinforcing bars in the base plate is tied before the anchor bolts are installed, and the upper layer of reinforcing bars in the base plate is tied after the anchor bolts are installed.

8. The installation method for a spent fuel storage device for heavy water reactors according to claim 3, characterized in that, The upper surface of the upper plate and the lower surface of the lower plate are coated with thermally sprayed zinc for corrosion protection, with a coating thickness of at least 350 μm.

9. The installation method for a spent fuel storage device for heavy water reactors according to claim 3, characterized in that, After the storage cylinder is in place and fixed, the outside of the support is sprayed with zinc. The first cavity formed between the bottom of the storage cylinder, the inner wall of the support and the upper plate is filled with grout until it is 10cm away from the bottom of the storage cylinder. A stiffening plate is provided on both sides of each lug of the support to connect the lug to the ring plate. The stiffening plate and the folding plate cooperate to form a second cavity. Grout is injected into the second cavity through the through hole reserved in the folding plate to fill the second cavity. Each anchor bolt is secured by a nut and bolt at the point where it protrudes from the lug, and is welded together. A sleeve is installed around the outside of the nut and bolt on the upper surface of the lug, and grout is poured into the sleeve to cover the nut and bolt inside the sleeve.

10. The installation method for a spent fuel storage device for heavy water reactors according to claim 3, characterized in that, Multiple discharge ports are provided on the top plate of the storage module, each discharge port facing a storage cylinder. The storage device also includes a support cylinder and a water-blocking cylinder. The support cylinder is installed on the inner wall of the corresponding discharge port to support it. The water-blocking cylinder is installed on the inner wall of the upper opening of the discharge port and is welded to the support cylinder below. The upper edge of the water-blocking cylinder is higher than the upper edge of the discharge port to prevent water accumulated on the outer surface of the top plate from flowing into the discharge port. The support cylinder and the water-blocking cylinder are installed using the following steps: Step 5: After the top plate support scaffolding and bottom formwork are installed, measure the preset gap between the storage cylinder and the support cylinder. Nail steel nails of the same length as the preset gap symmetrically on the bottom formwork along the outer wall of the storage cylinder to locate the inner diameter of the support cylinder. Reinforce the outer wall of the storage cylinder with extruded polystyrene boards of the same thickness as the preset gap. Hoist the first and second halves of the support cylinder to the top of the storage cylinder, assemble and fasten the first and second halves into a whole support cylinder, and tighten the bolts between the first and second halves. Step 6: The gap error between the support cylinder and the storage cylinder shall not exceed 0.5mm. The installation height of the support cylinder shall be adjusted based on the horizontal plane of the water baffle ring plate. After the support cylinder is positioned, shims shall be evenly inserted between the water baffle and the storage cylinder. After the water baffle and the support cylinder are circumferentially welded together, the elevation of the water baffle ring plate shall be checked and adjusted again to the design value, and then the shims shall be removed.

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