Cavity injection system, and bottom-supported heat insulation module for reactor pressure vessel

Abstract

A cavity injection system, and a bottom-supported heat insulation module (20) for a reactor pressure vessel (30). The bottom-supported heat insulation module (20) comprises a heat insulation assembly (21) and a lower supporting structure (23); the heat insulation assembly (21) is provided with a heat insulation cavity for the reactor pressure vessel (30) to be placed therein via the upper end; and the lower supporting structure (23) is arranged on the lower side of the heat insulation assembly (21) to form support at the bottom of the heat insulation module (20). The integral heat insulation module (20) with the lower supporting structure (23) allows for prefabrication and assembly outside a nuclear island plant and then integral hoisting to a reactor pit (10) for adjustment and fixation, and after hoisting, the lower supporting structure (23) forms support at the lower end.

Description

Reactor cavity water injection system and bottom-supported insulation module of reactor pressure vessel Technical Field

[0001] The present invention relates to the field of nuclear power, and more particularly to a reactor cavity water injection system of a nuclear power plant and a bottom-supported thermal insulation module of a reactor pressure vessel thereof. Background Art

[0002] After a serious accident in a pressurized water reactor nuclear power plant, the reactor core will gradually melt and form a high-temperature molten pool at the lower head of the reactor pressure vessel. At this time, if the heat of the molten pool is not effectively dissipated, the high-temperature molten material will melt through the lower head and enter the reactor pit through the breach.

[0003] The high-temperature molten material reacts with the concrete in the reactor cavity, releasing a large amount of non-condensable gases (H2, CO2, CO, etc.). This will have two consequences for the containment:

[0004] a) The containment fails due to overpressure caused by the continuous accumulation of non-condensable gas, and radioactive materials enter the atmosphere;

[0005] b) The molten material melts through the base plate, and radioactive materials enter the foundation, contaminating the soil and groundwater.

[0006] The melt retention strategy is a post-core melt response measure and a hallmark of third-generation reactors. After a core melt accident occurs, the core cavity water injection system begins injecting water into the reactor cavity, cooling the exterior of the reactor pressure vessel to maintain its integrity, thereby retaining the core melt within the reactor pressure vessel.

[0007] The reactor pressure vessel insulation layer is an important part of the reactor cavity water injection system. It provides an annular cavity flow channel for the reactor cavity water injection system, allowing cooling water to enter the annular cavity flow channel from the bottom of the insulation layer to cool the reactor pressure vessel. The generated steam-water mixture is discharged from the exhaust port of the insulation pipe, thereby achieving the in-core retention of the core melt.

[0008] At present, the insulation layer of the reactor pressure vessel cylinder section of the reactor cavity water injection system used at home and abroad is fixed by supporting parts fixed on the reactor pit embedded parts, among which the flow channel liner is connected and fixed to the lateral support parts by bolts, and the lateral support parts are fixed to the reactor pit embedded parts by welding.

[0009] The shell insulation support solution requires welding and adjustment of the reactor pressure vessel insulation lateral supports after the delivery of the pit civil structure. Finally, the flow channel lining and insulation blocks are installed. Due to the large number of insulation lateral supports, the high installation precision, and the limited space, the insulation installation period in the pit generally exceeds six months.

[0010] Especially after adopting the open-top construction method, the RPV (reactor pressure vessel) insulation installation work is on the critical path, and the difficulty of risk prevention and control in terms of project progress and quality will be more prominent. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to provide a reactor cavity water injection system and a bottom-supported insulation module for a reactor pressure vessel thereof in view of the above-mentioned defects of the prior art.

[0012] The technical solution adopted by the present invention to solve the technical problem is: constructing a bottom-supported insulation module for a reactor pressure vessel, comprising an insulation component and a bottom support structure;

[0013] The insulation assembly is provided with an insulation cavity for the reactor pressure vessel to be placed from the upper end;

[0014] The lower support structure is arranged on the lower side of the thermal insulation component to form a support at the bottom of the thermal insulation module.

[0015] In some embodiments, the insulation module further includes a horizontal limiting structure provided on the outer ring of the insulation component to limit the horizontal displacement of the insulation component.

[0016] In some embodiments, the horizontal limiting structure includes a plurality of horizontal limiters distributed around the circumference of the thermal insulation component.

[0017] In some embodiments, the horizontal limit structure includes at least one group of horizontal limiters, and each group of the horizontal limiters includes a plurality of horizontal limiters distributed around the circumference of the heat preservation component.

[0018] In some embodiments, the thermal insulation component is provided with a plurality of groups of horizontal limiters spaced apart in the height direction.

[0019] In some embodiments, the horizontal stopper is connected to the flow channel liner.

[0020] In some embodiments, the thermal insulation assembly includes a flow channel liner, and the flow channel liner includes a cylindrical body and a lower head located at the lower end of the cylindrical body.

[0021] In some embodiments, the insulation assembly includes an insulation layer located outside the flow channel liner.

[0022] In some embodiments, the outer wall of the flow channel lining is provided with an installation structure for installing the insulation layer.

[0023] In some embodiments, the mounting structure includes a plurality of annular support rings distributed axially on the outer wall surface of the flow channel lining.

[0024] In some embodiments, the thermal insulation layer includes several pieces, and at least one piece of the thermal insulation layer is provided between adjacent support rings.

[0025] In some embodiments, a gap is left between the thermal insulation layer and the flow channel lining.

[0026] In some embodiments, a water inlet is provided at the bottom of the thermal insulation component.

[0027] In some embodiments, the lower support structure includes a frame-type support base.

[0028] In some embodiments, the support base includes a plurality of legs, and the bottom of the pit is provided with an embedded part at the lower end of each leg.

[0029] A nuclear power plant reactor cavity water injection system comprises the above-mentioned thermal insulation module.

[0030] In some embodiments, the reactor cavity water injection system includes a reactor pit, the thermal insulation module is arranged in the reactor pit, and the bottom of the reactor pit supports the lower support structure.

[0031] In some embodiments, a support pad is provided on the outer periphery of the upper end of the stack pit for supporting the hanging platform of the reactor pressure vessel, and the upper end surface of the thermal insulation assembly is lower than the upper side surface of the support pad.

[0032] In some embodiments, the insulation module further includes a horizontal limiting structure provided on the outer ring of the insulation component, wherein the horizontal limiting structure abuts against the side wall of the stacking pit to limit the horizontal displacement of the insulation component.

[0033] In some embodiments, the inner wall surface of the stacking pit is provided with embedded parts for the horizontal limiting structure to abut against.

[0034] The implementation of the reactor cavity water injection system and the bottom-supported insulation module of the reactor pressure vessel of the present invention has the following beneficial effects: the integral insulation module with the lower support structure can be prefabricated and assembled outside the nuclear island plant, and then hoisted as a whole to the reactor pit for adjustment and fixation. After hoisting, the lower support structure forms a support at the lower end, which improves the stability of the insulation module. The installation method is simple and fast, and the installation and adjustment period in the reactor pit will be shortened to within one month, which significantly improves construction efficiency and enhances the economy and competitiveness of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0036] FIG1 is a schematic structural diagram of the assembled reactor pressure vessel and the through-type thermal insulation module of the reactor cavity water injection system in an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0038] As shown in FIG1 , a nuclear power plant reactor cavity water injection system in a preferred embodiment of the present invention includes a reactor pit 10 and an insulation module 20 disposed in the reactor pit 10. The reactor pit 10 is a civil engineering structure, typically made of concrete, and is formed with a reactor hole 11 for placing the insulation module 20 therein.

[0039] The insulation module 20 is an integrated structure, requiring no fixed connection to the reactor pit 10. It can be hoisted into the reactor cavity 11 for support and positioning, significantly shortening the installation and adjustment period for the insulation module 20 at the reactor pit 10. After the insulation module 20 is installed, the reactor pressure vessel 30 can be hoisted and placed into the insulation module 20, with the upper end of the reactor pressure vessel 30 supported by the upper side of the reactor pit 10.

[0040] Preferably, the insulation module 20 is a bottom-supported insulation module 20, including an insulation component 21 and a lower support structure 23, so that the lower support structure 23 and the insulation component 21 are an integral structure, which can be prefabricated and installed in advance outside the nuclear island plant, and then hoisted as a whole into the reactor pit 10.

[0041] The insulation component 21 is provided with an insulation cavity for the reactor pressure vessel 30 to be placed from the top. In this embodiment, the insulation component 21 includes a flow channel lining 211 and an insulation layer 212 located on the outside of the flow channel lining 211. An insulation cavity is formed on the inner side of the flow channel lining 211. The insulation component 21 is used for the reactor pressure vessel 30 to be placed from the top, so that an annular flow channel is formed between the insulation component 21 of the insulation module 20 and the reactor pressure vessel 30.

[0042] The flow channel liner 211 comprises a cylindrical body 2111 and a lower end cap 2112 at the lower end of the cylindrical body 2111. The cylindrical body 2111 and the lower end cap 2112 are welded or assembled to form an integrated structure, facilitating overall lifting. The cylindrical body 2111 and the lower end cap 2112 form a liner structure made of 304 stainless steel. The thickness is typically 10 mm, but can also be 8 mm, 12 mm, or 15 mm. The thickness of the upper end of the flow channel liner 211 can be increased.

[0043] The flow channel lining 211 can be mounted on the reactor pressure vessel 30 from the lower end. The insulation layer 212 is arranged on the outside of the flow channel lining 211. The insulation layer 212 is a metal reflective insulation layer whose main material is 304 stainless steel and can play a role in heat insulation.

[0044] Preferably, an annular support pad 12 is provided on the outer periphery of the upper end of the reactor pit 10. Of course, the support pad 12 can also be in block shape and distributed around the upper periphery of the reactor pit 10. The hanging platform 31 on the outer ring of the reactor pressure vessel 30 can be hung on the support pad 12, allowing the support pad 12 to support the reactor pressure vessel 30.

[0045] At the same time, the upper end surface of the insulation component 21 is lower than the upper side surface of the support pad 12, so that a gap is formed between the upper end surface of the insulation component 21 and the lower side surface of the insulation layer of the connecting pipe of the reactor pressure vessel 30 through the trapezoidal overlap, compensating for the space for the insulation module 20 to expand and extend upward after being heated, and avoiding contact and abutment between the insulation module 20 and the hanging platform 31 after being heated and expanded.

[0046] Furthermore, a lower support structure 23 is provided on the lower side of the lower end cap 2112. After the insulation module 20 is placed in the stacking pit 10, the lower support structure 23 is located at the bottom of the stacking pit 10, providing support for the bottom of the insulation module 20. The lower support structure 23 provides support at the lower end, positioning the lower end of the insulation module 20 and improving the stability of the insulation module 20.

[0047] The insulation module 20 is supported by a bottom-support structure. Once placed in the reactor pit 10, it forms a ventilation space with the reactor pit 10. Furthermore, after the reactor pressure vessel 30 is placed within the insulation module 20, an annular flow channel is formed between the module 20 and the reactor pressure vessel 30. The channel liner 211 is a cup-shaped structure with reinforced external supports to withstand loads and ensure channel integrity in the event of an accident.

[0048] A water inlet 2113 is provided at the bottom of the insulation assembly 21. In this embodiment, the water inlet 2113 is arranged on the insulation layer 212. Under accident conditions, water is injected into the reactor pit 10, so that the cooling water in the reactor pit 10 can enter the annular flow channel from the lower end, flow from the bottom to the top, and submerge the reactor pressure vessel 30, thereby cooling the reactor pressure vessel 30.

[0049] During normal operation, the insulation module 20 can play an insulation effect and reduce the heat loss of the reactor pressure vessel 30. When a core melt accident occurs, the core cavity water injection system starts to inject water into the reactor pit 10, and the cooling water enters the annular cavity flow channel formed between the insulation module 20 and the reactor pressure vessel 30 from the insulation module 20 to cool the reactor pressure vessel 30. The generated steam-water mixture is discharged from the exhaust port of the insulation pipe, thereby achieving the in-core retention of the core melt.

[0050] In some embodiments, the lower support structure 23 includes a support seat 231, the upper end of the support seat 231 is connected to the lower head 2112, serving as a hard support to improve the strength and stability of the support. At the same time, since the upper end of the insulation module 20 and the lower end of the insulation layer of the connecting pipe of the reactor pressure vessel 30 are overlapped in a trapezoidal shape with a gap, the vertical upward expansion of the entire insulation module 20 can be compensated.

[0051] The support base 231 is a frame structure. In this embodiment, it is composed of 4 to 8 bottom vertical support members (such as H-shaped steel) and "X" (or "M") beams to form an overall frame with a stable structure and better earthquake resistance.

[0052] Preferably, the support seat 231 includes several legs, which can provide balanced support and balance the load at each position. The bottom of the pit 10 is provided with embedded parts at the lower end of each leg. The embedded parts are made of metal material, which can enhance the supporting force of the bottom of the pit 10 and reduce the damage to the bottom of the pit 10 caused by the legs.

[0053] Alternatively, the lower support structure 23 itself is a frame structure with elastic support. For example, a spring can be set at the rotating joint position of the support structure. While providing support, it can also expand and contract downward if it is subjected to a large impact or under the action of thermal expansion.

[0054] In some embodiments, the outer wall of the flow channel liner 211 is provided with a mounting structure 213 for mounting the thermal insulation layer 212, facilitating the installation and fixation of the dispersed thermal insulation layer 212 on the outer side of the flow channel liner 211. The mounting structure 213 includes a plurality of annular support rings 2131 distributed axially on the outer wall of the flow channel liner 211. Each annular support ring 2131 is disposed along the outer circumferential wall of the flow channel liner 211 and is fixed by welding. On the one hand, it is used to mount and support the metal thermal insulation layer 212, and on the other hand, it serves to enhance the rigidity and strength of the cylindrical body 2111 and the lower head 2112 of the flow channel.

[0055] The support ring 2131 divides the outer side surface of the flow channel lining 211 into several blocks along the height direction. Furthermore, the insulation layer 212 includes several blocks, and one or more insulation layers 212 are arranged between adjacent support rings 2131. The insulation layer 212 can be installed piece by piece to facilitate control of the relative position between the insulation layer 212 and the flow channel lining 211.

[0056] Furthermore, after the insulation layer 212 is installed and secured, a certain gap is reserved between it and the flow channel lining plate 211 to accommodate circumferential thermal expansion differences and manufacturing and installation errors. The mounting structure 213 can also be a grid-like structure formed on the outer wall of the flow channel lining plate 211, or a plurality of ribs distributed circumferentially on the outer wall of the flow channel lining plate 211, dividing the outer surface of the flow channel lining plate 211 into several areas for the installation of the insulation layer 212.

[0057] In some embodiments, the insulation module 20 also includes a horizontal limiting structure 24 set on the outer ring of the insulation component 21 to limit the horizontal displacement of the insulation component 21. This can limit the horizontal swing of the insulation module 20 under normal working conditions and earthquake conditions after it is hung, making it less likely to shake, thereby improving the stability and safety of the insulation module 20.

[0058] Preferably, the inner wall surface of the stack hole 11 of the stack pit 10 is provided with an embedded part for the horizontal limiting structure 24 to abut against. The embedded part is made of metal material, which can improve the supporting strength of the inner wall surface of the stack hole and avoid damage to the inner wall surface of the stack hole 11 when the insulation module 20 shakes.

[0059] Furthermore, the horizontal limit structure 24 includes a plurality of horizontal limiters distributed around the circumference of the heat preservation component 21 , and the horizontal limiters can provide horizontal limit support in all circumferential directions, so that the horizontal limits in all directions are balanced.

[0060] The horizontal limiters on the circumference at the same height position form a group of horizontal limiters. Usually, the horizontal limiter structure 24 includes multiple groups of horizontal limiters, and each group of horizontal limiters includes several horizontal limiters distributed around the circumference of the insulation component 21.

[0061] In some embodiments, the entire insulation module 20 is distributed with 1-3 groups of horizontal limiters in the height direction, with 6-12 horizontal limiters arranged in each group. In the hot state, the gap between the horizontal limiter and the side wall of the stack pit 10 is theoretically zero. In the cold state, the gap between the horizontal limiter and the side wall of the stack pit 10 is reserved according to the radial thermal expansion of the flow channel lining 211, which can effectively limit the horizontal swing of the insulation module 20 under normal working conditions and seismic working conditions.

[0062] Preferably, given the relatively high height of the insulation assembly 21, several sets of horizontal stoppers can be spaced apart along the height of the insulation assembly 21 to provide horizontal support at different heights, ensuring that all positions along the height are supported by the horizontal stoppers. It is understood that only one set of horizontal stoppers can be provided around a single height position.

[0063] In order to improve the support stability and support strength of the horizontal limiter, the horizontal limiter can be connected to the cylindrical body 2111, and relying on the strength of the cylindrical body 2111, the horizontal limiter can support the insulation module.

[0064] The integrated insulation module 20 structure eliminates the traditional on-site block-type welding support and replaces it with an integral support structure of the insulation component 21 and the lower support structure 23, realizing the decoupling of the insulation module from the civil structure, greatly simplifying the on-site pre-buried workload and interfaces, and realizing prefabrication and assembly outside the nuclear island plant, and then hoisting the entire unit to the reactor pit 10 for adjustment and fixation. The on-site installation work of the reactor pit 10 is optimized from the traditional "split installation" to "integral hoisting", and the installation and adjustment period in the reactor pit 10 will be shortened to within one month, which significantly improves construction efficiency and enhances the economy and competitiveness of the unit.

[0065] It can be understood that the above technical features can be used in any combination without limitation.

[0066] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A bottom-supported thermal insulation module for a reactor pressure vessel, characterized in that: It comprises a heat preservation component (21) and a lower support structure (23); The heat preservation assembly (21) is provided with a heat preservation cavity into which the reactor pressure vessel (30) is placed from the upper end; The lower support structure (23) is arranged on the lower side of the thermal insulation component (21) to form support at the bottom of the thermal insulation module (20).

2. The bottom-through insulation module of the reactor pressure vessel according to claim 1, characterized in that: The heat preservation module (20) further comprises a horizontal limiting structure (24) arranged on the outer ring of the heat preservation component (21) to limit the displacement of the heat preservation component (21) in the horizontal direction.

3. The bottom-through insulation module of the reactor pressure vessel according to claim 2, characterized in that: The horizontal limit structure (24) comprises a plurality of horizontal limiters distributed around the circumference of the heat preservation component (21).

4. The bottom-through insulation module of the reactor pressure vessel according to claim 3, characterized in that: The horizontal limit structure (24) comprises at least one group of horizontal limiters, and each group of horizontal limiters comprises a plurality of horizontal limiters distributed around the circumference of the heat preservation component (21).

5. The bottom-through insulation module of the reactor pressure vessel according to claim 4, characterized in that: The heat-insulating component (21) is provided with a plurality of groups of horizontal limiters spaced apart in the height direction.

6. The bottom-through insulation module of the reactor pressure vessel according to any one of claims 2 to 5, characterized in that: The horizontal stopper is connected to the flow channel lining plate (211).

7. The bottom-through insulation module of the reactor pressure vessel according to claim 1, characterized in that: The heat-insulating component (21) comprises a flow channel lining plate (211), and the flow channel lining plate (211) comprises a cylindrical body (2111) and a lower sealing head (2112) located at the lower end of the cylindrical body (2111).

8. The bottom-through insulation module of the reactor pressure vessel according to claim 7, characterized in that: The thermal insulation component (21) comprises a thermal insulation layer (212) located outside the flow channel lining plate (211); The outer wall of the flow channel lining plate (211) is provided with a mounting structure (213) for mounting the thermal insulation layer (212); The mounting structure (213) comprises a plurality of annular support rings (2131) distributed along the axial direction on the outer wall surface of the flow channel lining plate (211); The thermal insulation layer (212) comprises a plurality of pieces, and at least one piece of the thermal insulation layer (212) is arranged between adjacent support rings (2131); A gap is left between the thermal insulation layer (212) and the flow channel lining plate (211); The bottom of the thermal insulation component (21) is provided with a water inlet (2113).

9. The bottom-through insulation module of the reactor pressure vessel according to claim 1, characterized in that: The lower support structure (23) comprises a frame-type support seat (231).

10. The bottom-through insulation module of the reactor pressure vessel according to claim 9, characterized in that: The support seat (231) comprises a plurality of supporting legs, and the bottom of the stacking pit (10) is provided with an embedded part at the lower end of each supporting leg.

11. A reactor cavity water injection system, characterized in that: Comprising the thermal insulation module (20) according to any one of claims 1 to 10.

12. The reactor cavity water injection system according to claim 11, characterized in that: The reactor cavity water injection system comprises a reactor pit (10), the heat preservation module (20) is arranged in the reactor pit (10), and the bottom of the reactor pit (10) supports the lower support structure (23).

13. The reactor cavity water injection system according to claim 12, characterized in that: A support pad (12) for supporting a hanging platform (31) of a reactor pressure vessel is provided on the outer periphery of the upper end of the reactor pit (10), and the upper end surface of the thermal insulation component (21) is lower than the upper side surface of the support pad (12).

14. The reactor cavity water injection system according to claim 12, characterized in that: The heat preservation module (20) further comprises a horizontal limiting structure (24) arranged on the outer ring of the heat preservation component (21), wherein the horizontal limiting structure (24) abuts against the side wall of the stacking pit (10) to limit the horizontal displacement of the heat preservation component (21).

15. The reactor cavity water injection system according to claim 14, characterized in that: The inner wall surface of the stacking pit (10) is provided with an embedded part for the horizontal limiting structure (24) to abut against.

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