A waterproof and drainage structure of a radioactive waste disposal cavern

Abstract

This invention belongs to the field of radioactive waste disposal technology and discloses a waterproof structure for a radioactive waste disposal cavern. It includes an outer waterproof layer composed of cave walls and a waterproof arch; an inner waterproof layer with a U-shaped cross-section composed of waterproof sidewalls and a waterproof base slab made of concrete; the outer waterproof layer is fastened to the outer waterproof layer, forming a cavity between the two layers; a permeable pipe communicating with the cavity is embedded in the waterproof arch; a drainage ditch is provided at the bottom of the cavity; and a drainage pipe preventing groundwater from rising is embedded below the waterproof base slab. This ensures that the inner waterproof layer is not soaked by groundwater from the rock strata, guaranteeing that radioactive elements will not pollute the surrounding environment with the flow of groundwater. This invention is suitable for artificial cavern disposal projects for radioactive waste.

Description

Technical Field

[0001] This invention belongs to the field of radioactive waste disposal technology, and specifically discloses a drainage structure for a radioactive waste disposal cavern. Background Technology

[0002] The migration of radionuclides underground is controlled by groundwater movement (transport), the propagation of contamination peaks (hydraulic dispersion), and the retention and release of radionuclides in the solid phase (interphase distribution). In all migration processes—transport, hydraulic dispersion, and interphase distribution—groundwater is the transport medium. Therefore, by minimizing the infiltration of surface water and groundwater into the disposal site through engineering measures and preventing contact between radioactive waste and water, the migration of radionuclides out of the disposal site can be inhibited, preventing the diffusion of radionuclides into the environment at unacceptable concentrations or quantities.

[0003] To effectively isolate the hydraulic connection between groundwater and the waste storage area during operation, it is necessary to carry out drainage, sealing, and grouting treatment on the fractured, faulted, and seepage areas of the sidewalls and arches of the disposal cave, the bedrock of the disposal cave floor, and areas with block formations and traces of seepage or dampness after grouting. This includes sealing the fractured rock around the disposal cave with grout. On the one hand, the geological structure of the disposal cave is complex, and the surrounding rock contains a large amount of groundwater. On the other hand, due to climate and chemical reactions, radioactive wastewater will also be generated within the space storing radioactive waste. How to reliably isolate the internal and external water bodies and prevent the leakage of pollution sources is a problem that construction technicians at the disposal cave need to study. Summary of the Invention

[0004] To address the problems in the background art, the present invention provides a drainage and waterproofing structure for a radioactive waste disposal cavern, the specific technical solution of which is as follows:

[0005] A drainage and waterproofing structure for a radioactive waste disposal cavern includes: an outer waterproof layer consisting of cavern walls and a waterproof arch; an inner waterproof layer with a U-shaped cross-section consisting of waterproof sidewalls and a waterproof base slab made of concrete; the outer waterproof layer is fastened to the outer waterproof layer, forming a cavity between the inner and outer waterproof layers; a permeable pipe communicating with the cavity is embedded in the waterproof arch; a drainage ditch is provided at the bottom of the cavity; and a drainage pipe is embedded below the waterproof base slab; both the permeable pipe and the drainage pipe are arranged in a main / branch T-shaped structure along the axis of the disposal cavern.

[0006] Preferably, the waterproof arch, waterproof base plate, and surrounding rock outside the tunnel wall are treated with cement grouting and surface sealing.

[0007] Preferably, the cavity wall has multiple drainage holes that communicate with the cavity along its normal direction.

[0008] Preferably, the inner waterproof layer is provided with a drainage pipe system leading to the radioactive wastewater collection tank outside the disposal cave.

[0009] Preferably, a nuclide blocking layer is arranged between the waterproof base plate and the surrounding rock of the tunnel bottom below it, which has been treated with cement grouting and surface sealing.

[0010] Preferably, the bottom of the cavity is filled with a sand layer, a clay layer, and a gravel layer from top to bottom, with the bottom of the gravel layer in contact with the upper surface of the nuclide blocking layer.

[0011] The beneficial effects of this invention are as follows:

[0012] 1) By sealing the cracks in the cave walls and floor, the groundwater in the cave disposal area is basically blocked. This not only reduces the adverse effects of long-term wet-dry cycles on the strength of the surrounding rock in the disposal area and helps to improve the long-term stability of the surrounding rock and a good operating environment, but also reduces the infiltration of groundwater into the cave and lowers the risk of nuclear waste coming into contact with water.

[0013] 2) During the operation of the disposal site, a cavity is used to isolate the inner and outer waterproof layers. Water seeping from the cave walls is drained through a dedicated drainage system. Water in contact with radioactive waste packages within the disposal unit is collected through a water collection trough to ensure that groundwater does not enter the waste stacking area during operation and that water in contact with radioactive waste packages does not enter the biosphere, thus completely severing the hydraulic connection between groundwater and radioactive waste within the cave. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the drainage system for the radioactive solid waste disposal cavern disposal facility in an embodiment of the present invention;

[0015] Figure 2 for Figure 1 Sectional view of AA in the middle;

[0016] Figure 3 This is a partial view of the AA section.

[0017] In the diagram: 1. Treatment cave, 2. Drainage ditch, 3. Water collection corridor, 4. Water collection trough, 5. Transverse intercepting trough, 6. Treatment unit, 7. Cave wall consolidation grouting, 8. Dome consolidation grouting, 9. Cave wall drainage pipe, 10. Floor slab consolidation grouting, 11. Dome, 12. Shotcrete high-performance waterproof concrete layer, 13. High impermeability concrete sidewall, 14. Concrete floor slab, 15. Cave wall, 16. Nuclide blocking layer, 17. Waste stacking, 18. Cavity water-tight zone, 19. Drainage sand layer, 20. Compacted clay layer, 21. Cement-stabilized open-graded crushed stone drainage layer, 22. Concrete sealing layer, 23. Floor slab drainage pipe. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely a part of the embodiments of this invention, and not all of them. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0019] This embodiment describes an underground multi-layered drainage and protection system structure for cavern disposal of low- and medium-level radioactive solid waste. Details include:

[0020] 1) Grouting and sealing structure for rock fissures around the cave;

[0021] The consolidation grouting treatment measures for the tunnel wall 15 and the dome 11 are consistent. The grouting includes tunnel wall anti-seepage consolidation grouting 7 and dome anti-seepage consolidation grouting 8. The grouting hole spacing is 1.5m × 1.5m, and the hole depth is set at 6m. The grouting method is to grout without cover after spraying concrete on the rock wall. The load-bearing structure under the concrete base slab 14 includes base slab consolidation grouting 10. The grouting hole spacing is 2m × 2m, and the hole depth is set at 6m into the rock.

[0022] 2) The concrete treatment unit of the inner waterproof layer is a U-shaped structure formed by the waterproof sidewalls, the bottom slab and the waterproof spray layer;

[0023] A high-impermeability concrete sidewall 13 and a high-impermeability concrete base slab 14 are set around the treatment unit 6. A high-performance waterproof concrete layer 12 is set on the top of the treatment cave 1 and the underside of the dome 11 to form a full interface isolation outside the treatment unit 6. A cavity water-proof zone 18 is formed between the cave wall 15 and the high-impermeability concrete sidewall 13 of the treatment cave 1, and between the high-performance waterproof concrete layer 12 and the dome 11.

[0024] 3) Drainage structure inside the tunnel;

[0025] During the filling operation period of the disposal cavern 1, the cavity water isolation area 18 can completely isolate the possible water seepage between the cavern wall 15 and the dome 11 from contacting the disposal unit 6. There are two parts of the drainage sources in the disposal cavern 1. The first part of the water is generated within the cavity water isolation area 18, which is pollution-free groundwater collected through pre-buried water permeable pipes between the cavern wall 15 of the disposal cavern 1 and the high anti-seepage concrete side wall 13, as well as between the waterproof spraying layer 12 and the dome 11. Among them, the water permeable pipes on the top of the disposal cavern and the bottom drain pipes are both in a dry / wet branch cross-shaped structure arranged along the axis of the disposal cavern, and are connected to the drainage ditches on both sides of the disposal cavern to achieve smooth and effective confluence and centralized discharge. The second part of the water is the condensate water on the radioactive waste package 17 and the concrete floor slab 14, and the condensate water on the high anti-seepage concrete side wall 13. The water containing pollution sources on the concrete floor slab 14 is discharged into the water collection gallery 3 through the transverse water intercepting groove 5 and the water collection groove 4. The drainage sand layer 19 and the compacted clay layer 20 are arranged in sequence at the bottom of the drainage ditch 2. The drainage sand layer 19 can effectively discharge a small amount of water seepage from the cavern wall. The compacted clay layer 20 supports the high anti-seepage concrete side wall 13 and the concrete floor slab 14 during the operation period to prevent the corners of the high anti-seepage concrete side wall 13 and the concrete floor slab 14 from deforming, and is used as a nuclide retardation material during the closure period. The cavern wall drain pipe 9 is arranged in the cavern wall 15 to accelerate the seepage of groundwater in the cavern wall.

[0026] 4) Anti-drainage layer of the concrete floor slab

[0027] The nuclide retardation layer 16, the cement stabilized open-graded crushed stone drainage layer 21, the concrete sealing layer 22 and the floor slab drain pipe 23 are arranged in sequence on the lower side of the concrete floor slab 14. The waterproof layer composed of the nuclide retardation layer 16, the cement stabilized open-graded crushed stone drainage layer 21 and the concrete sealing layer 22 can form a complete waterproof and drainage layer after the later closure to prevent the rise of groundwater. During the operation period, the drain pipe 23 arranged on the lower side of the concrete floor slab 14 can effectively discharge groundwater and ensure that groundwater will not seep into the disposal unit 6.

[0028] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A drainage and waterproofing structure for a radioactive waste disposal cavern, characterized in that: The system includes an outer waterproof layer consisting of the cave walls and a waterproof arch; an inner waterproof layer with a U-shaped cross-section consisting of waterproof sidewalls and a waterproof base slab made of concrete; the outer waterproof layer is fitted over the inner waterproof layer, forming a cavity between the two layers; a permeable pipe communicating with the cavity is embedded in the waterproof arch, a drainage ditch is provided at the bottom of the cavity, and a drainage pipe is embedded below the waterproof base slab; both the permeable pipe and the drainage pipe are arranged in a trunk / tributary shaped structure along the axis of the treatment cave; the surrounding rock outside the waterproof arch, waterproof base slab, and cave walls has been treated with cement grouting and surface sealing; multiple drainage holes communicating with the cavity are opened in the normal direction of the cave walls; a drainage pipe system leading to a radioactive wastewater collection tank outside the treatment cave is installed in the inner waterproof layer; a nuclide blocking layer is arranged between the waterproof base slab and the surrounding rock below it, which has been treated with cement grouting and surface sealing.

2. The drainage and waterproofing structure for a radioactive waste disposal cavern as described in claim 1, characterized in that: The bottom of the cavity is filled with a sand layer, a clay layer, and a gravel layer from top to bottom, with the bottom of the gravel layer in contact with the upper surface of the nuclide blocking layer.

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