Large fast reactor low-pressure containment system

Abstract

The invention belongs to the technical field of nuclear power station containment vessels, and particularly relates to a large fast reactor low-pressure containment vessel system which comprises a low-pressure containment system and a ventilation filtering system. The low-pressure containment system is used for containing radioactive substances in an operation state and an accident working condition, ensuring the air tightness of a containment boundary, and carrying out nuclide closed decay in the containment at the initial stage of an accident; the ventilation filtering system is used for filtering and discharging radioactive substances after short-period nuclide decay in the later period of an accident, and the radioactive level in a plant and the radioactive level in the environment are kept at the low level. According to the system, through coupling of the ventilation filtering system and the low-pressure containment system, the air tightness requirement of the containment can be met under the severe accident working condition, and meanwhile, the economical requirement of unit construction is met.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear power plant containment, and in particular relates to a large fast reactor low-pressure containment system. Background Art

[0002] The design of the containment is carried out under the accident conditions of the design basis, and it is necessary to ensure that the radioactive materials are completely sealed under the accident conditions to prevent leakage to the external environment. The design basis of the pressurized water reactor containment is the design basis accident conditions, and it must withstand the maximum internal pressure and temperature generated by the design basis accident (such as the loss of coolant accident). Under the conditions of the design basis accident (such as the loss of coolant accident), the pressurized water reactor nuclear power plant produces a large amount of high-temperature and high-pressure radioactive materials, mainly water vapor, inert gas, aerosol-combined iodine / cesium isotope mixture, etc. The peak pressure in the containment usually reaches the order of 0.4~0.5MPa. The design of the containment of the pressurized water nuclear power plant is a mature design type in China. The containment has high requirements for air tightness and strength design. It is a full-steel cladding design type, with local penetration items, and the personnel gate adopts a double-channel personnel airlock door design. The cable penetration adopts an electrical penetration. The prestressed system is designed and installed in the containment structure wall. The construction process is complex and the cost is high.

[0003] Even under severe accident conditions (containment design basis accident), liquid metal sodium cooled fast reactors produce less radioactive material than pressurized water reactors. It is mainly a mixture of inert gas and sodium aerosol. The peak pressure in the containment is kilopascals. The containment has airtightness design requirements but no strength design requirements. The BN series units are not designed with a containment. The design pressure of the containment of large liquid metal sodium cooled fast reactors is low, but the types and number of items that penetrate the containment boundary are large. The free volume of the containment of large liquid metal sodium cooled fast reactors is large, 2 to 3 times that of pressurized water reactor nuclear power plants, and the number of cable penetrations and pipeline penetrations is also more than that of pressurized water reactors. If a similar design to that of pressurized water reactor nuclear power plants is adopted, the cost of building the containment will increase significantly, which will have an adverse effect on reducing construction costs.

[0004] In addition, considering the increasingly high requirements for nuclear safety in the future, the structural strength design of the containment should take the most severe accident of the fast reactor (HCDA accident) that can be assumed as the design input to ensure the integrity of the containment structure under any operating conditions. In terms of source terms, the maximum core damage accident that can be considered in the safety analysis report is used as the input. The design basis of the fast reactor containment is the core melting under severe accident conditions, and it needs to withstand the transient shock wave and high temperature load generated by the assumed severe accident of core disintegration.

[0005] Therefore, how to ensure that any radioactive release to the environment of a liquid metal sodium cooled fast reactor under severe accident conditions is kept at a reasonably practicable and as low a level as possible, while achieving the airtightness requirements and meeting the economic requirements for unit construction, is an issue that urgently needs to be resolved in this field. Summary of the invention

[0006] The purpose of the present invention is to provide a low-pressure containment system for a large fast reactor. By coupling a ventilation and filtration system with a low-pressure containment system, the nuclides in the containment can be closed and decayed at the early stage of an accident. After the short-period nuclides decay, the ventilation and filtration system is used to filter and discharge them to maintain the radioactivity levels in the plant and the environment at a low level. Under severe accident conditions, the airtightness requirements of the containment can be achieved, and the economic requirements of the unit construction can be met at the same time.

[0007] The technical solution to achieve the purpose of the present invention is: A large fast reactor low-pressure containment system comprises a low-pressure containment system and a ventilation and filtration system; the low-pressure containment system is used to contain radioactive materials in operation and accident conditions, ensure the airtightness of the containment boundary, and perform closed decay of nuclides in the containment in the early stage of an accident; the ventilation and filtration system is used to filter and discharge radioactive materials after the decay of short-period nuclides in the late stage of an accident, so as to maintain the radioactivity level in the plant and the environment at a low level; the low-pressure containment system comprises a containment; the containment comprises a reactor hall, a reactor pit, a well for installing new component transport barrels in the plant, and boundary items; the outer boundary connected to the reactor hall, the reactor pit, and the well for installing new component transport barrels in the plant constitutes the containment boundary; the boundary items are sealed and connected to the concrete structure of the containment boundary.

[0008] Furthermore, the reactor hall, reactor pit, and transport barrel installation wells in the new component plant are all non-prestressed concrete structures, the reactor pits are all provided with steel facings, the top of the reactor hall is provided with steel formwork, the bottom plate of the reactor hall is provided with steel facings, and the concrete walls around the reactor hall are painted with nuclear island paint to form a nuclear island paint coating of the concrete structure of the containment boundary; the transport barrel installation wells in the new component plant are all coated with nuclear island paint to form a nuclear island paint coating of the concrete structure of the containment boundary.

[0009] Furthermore, the low-pressure containment system also includes a core melt collector. A main container is provided in the reactor pit, and a core melt collector is provided at the bottom of the main container.

[0010] Furthermore, the low-pressure containment system also includes a sodium leakage receiving and suppression disk, and a sodium leakage receiving and suppression disk is provided at the bottom of the pile pit.

[0011] Furthermore, the low-pressure containment system also includes a stack top protection cover, which is arranged on the top of the main container.

[0012] Furthermore, the reactor hall is arranged on the reactor pit, and the reactor hall is connected with the reactor pit to form a mushroom-shaped structure. The installation well for transport barrels in the new component factory is arranged under the bottom plate of the reactor hall. The reactor hall, the reactor pit and the installation well for transport barrels in the new component factory are connected to form a sealed structure.

[0013] Furthermore, the boundary items include: pipes, mechanical penetrations, cable penetrations, personnel access passages, equipment access passages, fuel transfer passages, and containment boundary cover plates that constitute the extended part of the containment; the pipes, mechanical penetrations, cable penetrations, personnel access passages, equipment access passages, fuel transfer passages, and containment boundary cover plates that constitute the extended part of the containment are respectively arranged on the containment boundary.

[0014] Furthermore, an equipment access passage is opened on the wall of the reactor hall near the bottom plate, and a personnel access passage is opened on the installation well of the transport barrel in the new component factory and the wall of the reactor hall; pipes, mechanical penetrations and cable penetrations constituting the extension of the containment are arranged on the wall of the reactor hall; containment isolation valves are installed upstream and downstream of the mechanical penetrations respectively; a fuel transfer channel and a containment boundary cover are opened on the bottom plate of the reactor hall.

[0015] Furthermore, the cable penetration is sealed and connected to the concrete structure at the boundary of the containment shell by means of cable plugging and sealing; the cable penetration comprises an embedded casing and a cable, the embedded casing is placed in the concrete structure at the boundary of the containment shell, the cables are arranged in the embedded casing at intervals, gaps are formed between the cables and between the cables and the embedded casings, high-density silicone sealant is filled in the gaps, so that the embedded casing with the cable is sealed and plugged; fire-resistant silicone sealant is coated on the junction of the embedded casing and the concrete structure at the boundary of the containment shell and on the surface of the high-density silicone sealant.

[0016] Furthermore, the mechanical penetration is placed in the concrete structure of the containment boundary, and a wing ring is provided on the outer periphery of the mechanical penetration, which extends into the concrete structure of the containment boundary. The junction between the mechanical penetration and the concrete structure of the containment boundary is first coated with polysulfide rubber, and then the polysulfide rubber is covered with metal foil for overlap, and then nuclear island paint is coated on the metal foil to form a nuclear island paint coating. The nuclear island paint coating covers from the junction of the mechanical penetration and the concrete structure of the containment boundary to the overlap of the nuclear island paint coating with the concrete structure of the containment boundary.

[0017] Furthermore, the boundary door frames of the personnel entrance and exit passages and the equipment entrance and exit passages are fitly connected to the concrete structure of the containment boundary. At the junction of the boundary door frame and the concrete structure of the containment boundary, polysulfide rubber chamfering is first used, and then nuclear island paint is applied to form a nuclear island paint coating. The nuclear island paint coating covers from the junction of the boundary door frame and the concrete structure of the containment boundary to the overlap of the nuclear island paint coating with the concrete structure of the containment boundary.

[0018] Furthermore, the containment boundary cover is provided with a double-pass sealing ring, which has the conditions for single-body sealing test; during the installation and commissioning stage of the power plant, the containment boundary cover is movable; after the installation and commissioning of the power plant is completed, the infrequently used containment boundary cover is connected to the reactor hall bottom plate steel covering by welding, and the weld surface is subjected to 100% penetration inspection; a gate valve is provided at the junction of the fuel transfer channel and the reactor hall bottom plate steel covering, and the fuel transfer channel is connected or closed by controlling the opening and closing of the gate valve.

[0019] Furthermore, the ventilation and filtration system includes an air supply pipeline, an exhaust pipeline, a high-efficiency filter, an exhaust fan, an exhaust chimney, an exhaust isolation valve, an air supply isolation valve, and an air supply fan; air supply pipelines are respectively provided between the reactor top protection cover and the reactor hall, and between the reactor pit and the reactor hall, the air supply pipeline inlet is provided outside the reactor hall, the air supply pipeline first outlet is provided in the reactor top protection cover, and the air supply pipeline second outlet is provided in the reactor pit; an air supply isolation valve and an air supply fan are provided on the air supply pipeline; an exhaust chimney is provided outside the reactor hall, an exhaust pipeline is provided between the reactor pit and the exhaust chimney, the exhaust pipeline outlet is connected to the exhaust chimney inlet, and the exhaust pipeline inlet is connected to the reactor pit; an exhaust isolation valve, a high-efficiency filter, and an exhaust fan are provided on the exhaust pipeline.

[0020] The beneficial technical effects of the present invention are: 1. The present invention provides a large fast reactor low-pressure containment system, which can play a sealing role in severe accident conditions to prevent radioactive substances from leaking into the environment, and can also withstand the impact of external natural disasters and man-made events.

[0021] 2. A large-scale fast reactor low-pressure containment system provided by the present invention ensures that any radioactive release from the sodium-cooled fast reactor to the environment is kept at a reasonably practicable and as low a level as possible through the coupling of a post-accident ventilation and filtration system with the low-pressure containment system, and does not exceed the regulatory emission limit of radioactive release under operating conditions, and does not exceed the acceptable limit of radioactive release under accident conditions.

[0022] 3. In a large fast reactor low-pressure containment system provided by the present invention, the containment (including the reactor hall, reactor pit, and the installation well for transport barrels of new components in the factory) adopts non-prestressed concrete walls, which effectively reduces the construction cost.

[0023] 4. The present invention provides a large fast reactor low-pressure containment system, which seals concrete microcracks by coating nuclear island paint on non-prestressed concrete walls and the junctions between wall-penetrating objects and walls, ensuring that the nuclear island paint coating maintains integrity and adhesion after severe accident load stretching, and is resistant to sodium or alkaline substances after combustion, thereby meeting the containment airtightness requirements.

[0024] 5. In a large fast reactor low-pressure containment system provided by the present invention, the containment serves as a barrier to envelop radioactive materials and avoid adverse effects on the external environment due to low-bay emissions.

[0025] 6. A large fast reactor low-pressure containment system provided by the present invention can collect and extinguish sodium fire in the reactor pit by providing a sodium leakage receiving and suppression plate at the bottom of the reactor pit, thereby ensuring the integrity of the main container and the integrity of the containment boundary.

[0026] 7. A large-scale fast reactor low-pressure containment system provided by the present invention has a core melt collector at the bottom of the main container to ensure that after 100% of the core melts in a serious accident condition, all the molten fuel will be collected and cooled, ensuring that most of the radioactive materials are contained inside the main container, avoiding a large sodium fire after the main container melts through.

[0027] 8. The present invention provides a large-scale fast reactor low-pressure containment system, which can ensure the sealing of the containment and facilitate construction by adopting a specific sealing connection method for the containment boundary wall penetration items (including embedded parts, boundary doors, mechanical penetrations, and cable penetrations), thereby having good economy.

[0028] 9. The present invention provides a large-scale fast reactor low-pressure containment system, which seals and connects the cable penetrations to the concrete structure at the boundary of the containment by using a cable plugging and sealing method, arranges multiple cables at intervals, and uses silicone sealant to seal the cable gaps, thereby ensuring that the cable penetration positions are sealed and waterproof in severe accident environments, while preventing the control signals of the cables from being damaged, thereby saving economic costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of a low-pressure containment system for a large fast reactor provided by the present invention; Figure 2 A front view and a top cross-sectional view of the junction of the embedded parts and the concrete structure of the containment boundary in a large fast reactor low-pressure containment system provided by the present invention; Figure 3 A cross-sectional view of the junction of a mechanical penetration and a concrete structure of a containment boundary in a large fast reactor low-pressure containment system provided by the present invention; Figure 4 A top view cross-sectional view of the junction of the concrete structure of the boundary door and the containment boundary in a large fast reactor low-pressure containment system provided by the present invention; Figure 5 The present invention provides a cross-sectional view of the junction between a cable penetration piece and a concrete structure at the containment boundary in a large fast reactor low-pressure containment system.

[0030] In the figure: 1. Reactor core; 2. Core melt collector; 3. Main container; 4. Leakage sodium receiving suppression plate; 5. Top protection cover; 6. Reactor hall; 7. Pit; 8. Installation well for transport barrels of new components in the factory; 9. Pipes forming the extension of the containment; 10. Containment isolation valve; 11. Mechanical penetrations; 12. Cable penetrations; 13. Personnel access passage; 14. Equipment access passage; 15. Fuel transfer passage; 16. Full shell; 17. Containment boundary cover; 18. High-efficiency filter; 19. Exhaust fan; 20. Exhaust chimney; 21. Exhaust isolation valve; 22. Supply air isolation valve; 23. Supply air fan; 31. Embedded parts; 32. Nuclear island paint coating; 33. Metal foil; 34. Wing ring; 35. Polysulfide rubber; 36. Wall; 37. Door frame; 38. Embedded casing; 39. Fireproof silicone sealant; 40. Cable; 41. High-density silicone sealant. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0032] A large-scale fast reactor low-pressure containment system provided by the present invention comprises a low-pressure containment system and a ventilation and filtration system; the low-pressure containment system is used for containing radioactive materials in an operating state and an accident condition, ensuring the air tightness of the containment boundary, and performing closed decay of nuclides in the containment in the early stage of an accident; the ventilation and filtration system is used for filtering and discharging radioactive materials after the short-period nuclides decay in the late stage of an accident, so as to maintain the radioactivity levels in the plant and the environment at a low level.

[0033] like Figure 1 As shown, the low-pressure containment system includes a containment vessel 16 , a core melt collector 2 , a sodium leakage receiving and suppression plate 4 , and a reactor top protective cover 5 .

[0034] Containment 16 includes containment structures and containment subsystems and facilities that are required to perform functions under specific accidents. Containment 16 is not designed with a prestressed system and has no strength test requirements, but has airtightness test requirements. The containment structure is a reinforced concrete structure with a square dome.

[0035] The containment structure includes the reactor hall 6, the pile pit 7, and the installation well 8 for transport barrels in the new component plant. The reactor hall 6 is arranged on the pile pit 7, and the reactor hall 6 is connected with the pile pit 7 to form a mushroom-shaped structure. The installation well 8 for transport barrels in the new component plant is arranged under the bottom plate of the reactor hall 6. The reactor hall 6, the pile pit 7, and the installation well 8 for transport barrels in the new component plant are connected to form a sealed structure. The outer boundary where the reactor hall 6, the pile pit 7, and the installation well 8 for transport barrels in the new component plant are connected (i.e., the top, wall and bottom plate of the reactor hall 6, the wall and bottom plate of the pile pit 7, and the outer wall of the installation well 8 for transport barrels in the new component plant) constitutes the containment boundary.

[0036] Reactor hall 6, reactor pit 7, and new component factory transport barrel installation well 8 are all non-prestressed concrete structures. The top of reactor hall 6 is equipped with steel formwork, and the bottom plate of reactor hall 6 is equipped with steel coating, which can withstand the high-temperature sodium fire in the hall and ensure the integrity of the containment boundary at the location, airtightness and other functions are normal. The concrete walls around reactor hall 6 are painted with nuclear island paint with high adhesion, high elasticity, high tensile force, and strong alkali resistance, forming a nuclear island paint coating of the concrete structure of the containment boundary, sealing concrete microcracks, and ensuring that the nuclear island paint coating maintains integrity, adhesion, and tolerance to sodium or alkaline substances after burning after severe accident load stretching. The reactor pit 7 is completely equipped with steel coating, and the bottom of the reactor pit 7 is equipped with a sodium leakage receiving suppression plate 4, which is used to collect and extinguish the sodium fire in the reactor pit, ensure the integrity of the main container, and ensure the integrity of the containment boundary. All 8 transport barrel installation wells in the new component factory are coated with nuclear island paint to form a nuclear island paint coating on the concrete structure of the containment boundary, which seals the micro cracks in the concrete and ensures that the nuclear island paint coating maintains integrity, adhesion, and tolerance to sodium or alkaline substances after combustion after severe accident load stretching.

[0037] The main container 3 is arranged in the reactor pit 7, and a top protective cover 5 is arranged on the top of the main container 3 to prevent the radioactive materials leaking from the main container 3 from leaking into the reactor hall 6. A core melting collector 2 is arranged at the bottom of the main container 3 to ensure that after 100% of the core is melted, all the molten fuel will be collected and cooled. Therefore, when the core melts in a serious accident condition, there is no need to consider the large sodium fire after the main container 3 melts through. Most of the radioactive materials are contained inside the main container 3. It is only necessary to consider a small amount of primary sodium entering the top protective cover 5 through the top of the main container and leaking into the containment 16. The containment acts as a barrier to envelop the radioactive materials, avoid the adverse effects on the external environment due to low-shelf emissions, and achieve the purpose of closed decay of the nuclei in the containment at the early stage of the accident.

[0038] The containment subsystem and facilities, i.e., the boundary items, include the pipes 9, mechanical penetrations 11, cable penetrations 12, personnel access passages 13, equipment access passages 14, fuel transfer passages 15, and containment boundary covers 17 that constitute the extended portion of the containment. The pipes 9, mechanical penetrations 11, cable penetrations 12, personnel access passages 13, equipment access passages 14, fuel transfer passages 15, and containment boundary covers 17 that constitute the extended portion of the containment are respectively arranged on the containment boundary and are sealed and connected to the junction of the concrete structure of the containment boundary.

[0039] In a specific embodiment, an equipment access passage 14 is opened on the wall of the reactor hall 6 near the bottom plate, and a transport barrel installation well 8 in the new component factory and a personnel access passage 13 are opened at multiple levels on the wall of the reactor hall 6; a pipe 9, a mechanical penetration 11, and a cable penetration 12 constituting an extension of the containment are provided on the wall of the reactor hall 6; containment isolation valves 10 are installed upstream and downstream of the mechanical penetration 11, respectively; a fuel transfer passage 15 is opened on the bottom plate of the reactor hall 6, and a containment boundary cover 17 is provided.

[0040] Considering the large volume of the large fast reactor containment 16 and the large number of wall-penetrating boundary items, the use of nuclear island paint applied to the concrete wall and the junction between the wall-penetrating boundary items and the wall can seal the concrete microcracks, ensure the integrity of the concrete wall, and meet the containment airtightness requirements. Factors affecting the containment leakage rate include: containment isolation valve 10, mechanical penetrations 11, cable penetrations 12, personnel access passages 13, equipment access passages 14, fuel transfer passages 15, containment boundary cover plates 17, walls, etc.

[0041] The personnel access channel 13, the equipment access channel 14, the fuel transfer channel 15, and the containment boundary cover 17 need to be able to withstand the high temperature airtightness test in the sodium fire environment under severe accident conditions.

[0042] During the installation and commissioning phase of the power plant, the containment boundary cover 17 is designed to be movable and equipped with a double-line sealing ring, i.e., a pressure charging port, and has the conditions for a single-unit sealing test. For the containment boundary cover 17 that is not commonly used, after the installation and commissioning of the power plant is completed, it can be changed to a welding method to connect the containment boundary cover 17 to the bottom plate steel cladding of the reactor hall 6, and a 100% penetration test is performed on the weld surface.

[0043] A gate valve is provided at the junction of the fuel transfer channel 15 and the steel cladding of the bottom plate of the reactor hall 6. By controlling the opening and closing of the gate valve, the fuel transfer channel 15 is connected or closed. The gate valve is connected to the steel cladding of the bottom plate of the reactor hall 6 by welding.

[0044] The embedded parts 31 of the concrete structure (reactor hall wall) of the containment boundary are used for rooting welding support brackets, etc., and are embedded in the concrete structure in advance. The sealing connection method with the junction is as follows: Figure 2 As shown. Nuclear island paint is applied to the edges around the embedded part 31 to form a nuclear island paint coating 32, and the nuclear island paint coating 32 smoothly transitions at the junction of the embedded part 31 and the concrete structure at the boundary of the containment. The nuclear island paint coating 32 covers from the junction of the embedded part 31 and the concrete structure at the boundary of the containment to the nuclear island paint coating overlapped with the concrete structure at the boundary of the containment, and the boundary of the nuclear island paint coating 32 gradually fades.

[0045] The sealing connection method at the junction of the mechanical penetration 11 and the concrete structure of the containment boundary (reactor hall wall) is as follows: Figure 3 As shown. The mechanical penetration 11 is placed in the concrete structure (i.e., wall 36) at the boundary of the containment, and a wing ring 34 is provided on the periphery of the mechanical penetration 11, and the wing ring 34 is extended into the concrete structure (i.e., wall 36) at the boundary of the containment to increase the fixing strength of the mechanical penetration 11. Before the concrete structure (i.e., wall 36) at the boundary of the containment is cast, a hole is left using the mechanical penetration 11 provided with the wing ring 34. At the junction of the mechanical penetration 11 and the concrete structure at the boundary of the containment, polysulfide rubber 35 is first coated, and then metal foil 33 is covered on the polysulfide rubber 35 for overlap, and then nuclear island paint is coated on the metal foil 33 to form a nuclear island paint coating 32, and the nuclear island paint coating 32 covers from the junction of the mechanical penetration 11 and the concrete structure at the boundary of the containment to the overlap of the nuclear island paint coating with the concrete structure at the boundary of the containment.

[0046] The sealing connection method at the junction of the pipeline 9 constituting the extension of the containment and the concrete structure at the boundary of the containment is the same as the sealing connection method at the junction of the mechanical penetration 11 and the concrete structure at the boundary of the containment, such as Figure 3 shown.

[0047] In a specific embodiment, the metal foil can be a foil such as tin foil or aluminum foil.

[0048] The sealing connection method at the junction of the boundary door of the personnel access channel 13 and the equipment access channel 14 and the concrete structure of the containment boundary (the wall of the transport barrel installation well in the new component factory and the wall of the reactor hall), such as Figure 4 The boundary door frame 37 is fitted and connected to the concrete structure of the containment boundary (i.e., the wall 36). At the junction of the boundary door frame 37 and the concrete structure of the containment boundary (i.e., the wall 36), polysulfide rubber 35 is first used for chamfering, and then nuclear island paint is applied to form a nuclear island paint coating 32. The nuclear island paint coating 32 covers from the junction of the boundary door frame 37 and the concrete structure of the containment boundary to the overlap of the nuclear island paint coating with the concrete structure of the containment boundary.

[0049] The cable penetration 12 is sealed and connected to the concrete structure (reactor hall wall) of the containment vessel boundary by a cable plugging and sealing method. The sealing connection method is as follows: Figure 5As shown. The cable penetration 12 includes an embedded sleeve 38 and a cable 40. The embedded sleeve 38 is placed in the concrete structure (i.e., the wall 36) at the boundary of the containment. The cables 40 are arranged in the embedded sleeve 38 at intervals. Gaps are formed between the cables 40 and between the cables 40 and the embedded sleeve 38. High-density silicone sealant 41 is filled in the gaps, so that the embedded sleeve 38 with the cables 40 is sealed; the interface between the embedded sleeve 38 and the concrete structure (i.e., the wall 36) at the boundary of the containment and the surface of the high-density silicone sealant 41 are coated with fire-resistant silicone sealant 39. Before the wall 36 is poured, the embedded sleeve 38 is used to leave holes. Before sealing the cables, first arrange the cables 40 in the holes of the embedded sleeve 38 at intervals, leaving sufficient gaps between the cables 40 and between the cables 40 and the embedded sleeve 38, and then use high-density silicone sealant 41 to fully fill all the gaps in the holes; finally, use fire-resistant silicone sealant 39 to coat the junction between the embedded sleeve 38 and the wall 36 and the surface of the high-density silicone sealant 41.

[0050] like Figure 1 As shown, the ventilation and filtration system includes an air supply pipeline, an exhaust pipeline, a high-efficiency filter 18, an exhaust fan 19, an exhaust chimney 20, an exhaust isolation valve 21, an air supply isolation valve 22, and an air supply fan 23.

[0051] Air supply pipelines are respectively provided between the reactor top protection cover 5 and the reactor hall 6, and between the reactor pit 7 and the reactor hall 6. The inlet of the air supply pipeline is provided outside the reactor hall 6, the first outlet of the air supply pipeline is provided in the reactor top protection cover 5, and the second outlet of the air supply pipeline is provided in the reactor pit 7; since the reactor hall 6 and the reactor pit 7 are connected, air can be supplied to the reactor hall 6 and the reactor pit 7 at the same time through the second outlet of the air supply pipeline provided in the reactor pit 7; an air supply isolation valve 22 and an air supply fan 23 are provided on the air supply pipeline; the air supply isolation valve 22 is provided in the reactor hall 6, and the air supply fan 23 is provided outside the reactor hall 6.

[0052] An exhaust chimney 20 is provided outside the reactor hall 6, an exhaust pipeline is provided between the reactor pit 7 and the exhaust chimney 20, the outlet of the exhaust pipeline is connected to the inlet of the exhaust chimney 20, and the inlet of the exhaust pipeline is communicated with the reactor pit 7. Since the reactor hall 6 and the reactor pit 7 are communicated, the radioactive substances in the reactor hall 6 and the reactor pit 7 can be discharged simultaneously through the inlet of the exhaust pipeline (the reactor top protection cover 5 is not the last shield, and the exhaust is mainly to prevent the low-rise discharge through the last shield reactor hall 6, so the exhaust pipeline is not arranged in the reactor top protection cover 5); an exhaust isolation valve 21, a high-efficiency filter 18, and an exhaust fan 19 are provided on the exhaust pipeline, the exhaust isolation valve 21 is arranged outside the reactor pit 7, the high-efficiency filter 18 and the exhaust fan 19 are arranged outside the reactor hall 6 or outside the reactor pit 7, and the radioactive aerosol is filtered by the high-efficiency filter 18.

[0053] The sealing connection method at the junction of the air supply pipeline, the exhaust pipeline and the concrete structure of the containment shell boundary is the same as the sealing connection method at the junction of the mechanical penetration 11 and the concrete structure of the containment shell boundary, such as Figure 3 shown.

[0054] In the later stage of the accident, the post-accident ventilation and filtration system is turned on, the exhaust isolation valve 21 and the air supply isolation valve 22 are opened, the exhaust fan 19 and the air supply fan 23 are operated, and the radioactive sodium aerosol and fission products are filtered and discharged through the exhaust chimney 20 to minimize the radioactive consequences to the environment. The post-accident ventilation and filtration system of the containment ensures the controllable discharge of radioactive materials, maintains a slight negative pressure in the later stage of the containment accident, and filters the radioactive sodium aerosol and fission product aerosol in the containment.

[0055] The present invention is described in detail above with reference to the accompanying drawings and embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. The contents not described in detail in the present invention can adopt the existing technology.

Claims

1. A large fast reactor low-pressure containment system, characterized in that: It includes a low-pressure containment system and a ventilation and filtration system; the low-pressure containment system is used to contain radioactive materials in the operating state and accident conditions, ensure the airtightness of the containment boundary, and carry out closed decay of nuclides in the containment in the early stage of the accident; the ventilation and filtration system is used to filter and discharge radioactive materials after the short-period nuclides decay in the later stage of the accident, so as to maintain the radioactivity level in the plant and the environment at a low level; the low-pressure containment system includes a containment (16); the containment (16) includes a reactor hall (6), a reactor pit (7), a new component plant transport barrel installation well (8) and boundary items; the outer boundary connected to the reactor hall (6), the reactor pit (7) and the new component plant transport barrel installation well (8) constitutes the containment boundary; the boundary items are sealed and connected to the concrete structure of the containment boundary.

2. A large fast reactor low-pressure containment system according to claim 1, characterized in that: The reactor hall (6), the reactor pit (7), and the new component plant transport barrel installation well (8) are all non-prestressed concrete structures. The reactor pit (7) is completely provided with a steel coating, the top of the reactor hall (6) is provided with a steel formwork, the bottom plate of the reactor hall (6) is provided with a steel coating, and the concrete walls around the reactor hall (6) are painted with nuclear island paint to form a nuclear island paint coating of the concrete structure of the containment boundary; the new component plant transport barrel installation well (8) is completely coated with nuclear island paint to form a nuclear island paint coating of the concrete structure of the containment boundary.

3. A large fast reactor low-pressure containment system according to claim 1, characterized in that: The low-pressure containment system further comprises a core melt collector (2), a main container (3) is provided in the reactor pit (7), and the core melt collector (2) is provided at the bottom of the main container (3).

4. A large fast reactor low-pressure containment system according to claim 1, characterized in that: The low-pressure containment system further comprises a sodium leakage receiving and suppressing disk (4), and a sodium leakage receiving and suppressing disk (4) is provided at the bottom of the stack pit (7).

5. A large fast reactor low-pressure containment system according to claim 1, characterized in that: The low-pressure containment system further comprises a stack top protection cover (5), wherein the stack top protection cover (5) is arranged on the top of the main container (3).

6. A large fast reactor low-pressure containment system according to claim 1, characterized in that: The reactor hall (6) is arranged on the reactor pit (7), the reactor hall (6) and the reactor pit (7) are connected to form a mushroom-shaped structure, the new component factory transport barrel installation well (8) is arranged under the bottom plate of the reactor hall (6), the reactor pit (7) and the new component factory transport barrel installation well (8) are connected to form a sealed structure.

7. A large fast reactor low-pressure containment system according to claim 1, characterized in that: The boundary items include: a pipeline (9) constituting an extension of the containment, a mechanical penetration (11), a cable penetration (12), a personnel access passage (13), an equipment access passage (14), a fuel transfer passage (15), and a containment boundary cover (17). The pipeline (9) constituting an extension of the containment, a mechanical penetration (11), a cable penetration (12), a personnel access passage (13), an equipment access passage (14), a fuel transfer passage (15), and a containment boundary cover (17) are respectively arranged on the containment boundary.

8. A large fast reactor low-pressure containment system according to claim 7, characterized in that: The reactor hall (6) has an equipment access passage (14) on its wall near the bottom plate, a new component factory transport barrel installation well (8) and a personnel access passage (13) on its wall; a pipe (9) constituting an extension of the containment shell, a mechanical penetration piece (11), and a cable penetration piece (12) are provided on the wall of the reactor hall (6); containment shell isolation valves (10) are respectively installed upstream and downstream of the mechanical penetration piece (11); a fuel transfer passage (15) and a containment shell boundary cover plate (17) are provided on the bottom plate of the reactor hall (6).

9. A large fast reactor low-pressure containment system according to claim 7, characterized in that: The cable penetration piece (12) is sealed and connected to the concrete structure at the boundary of the containment shell by means of cable plugging and sealing. The cable penetration piece (12) comprises a pre-buried sleeve (38) and a cable (40). The pre-buried sleeve (38) is placed in the concrete structure at the boundary of the containment shell. The cables (40) are arranged in the pre-buried sleeve (38) at intervals. Gaps are formed between the cables (40) and between the cables (40) and the pre-buried sleeve (38). High-density silicone sealant (41) is filled in the gaps so that the pre-buried sleeve (38) in which the cables (40) are arranged is sealed and plugged. The interface between the pre-buried sleeve (38) and the concrete structure at the boundary of the containment shell and the surface of the high-density silicone sealant (41) are coated with fire-resistant silicone sealant (39).

10. A large fast reactor low-pressure containment system according to claim 7, characterized in that: The mechanical penetration piece (11) is placed in a concrete structure at the boundary of the containment shell. A wing ring (34) is provided on the periphery of the mechanical penetration piece (11). The wing ring (34) extends into the concrete structure at the boundary of the containment shell. A polysulfide rubber (35) is first coated at the junction of the mechanical penetration piece (11) and the concrete structure at the boundary of the containment shell. A metal foil (33) is then covered on the polysulfide rubber (35) for overlap. A nuclear island paint is then coated on the metal foil (33) to form a nuclear island paint coating (32). The nuclear island paint coating (32) covers from the junction of the mechanical penetration piece (11) and the concrete structure at the boundary of the containment shell to the point where the nuclear island paint coating overlaps with the concrete structure at the boundary of the containment shell.

11. A large fast reactor low-pressure containment system according to claim 7, characterized in that: The boundary door frames (37) of the personnel access passage (13) and the equipment access passage (14) are fitted and connected to the concrete structure of the containment boundary. At the junction of the boundary door frame (37) and the concrete structure of the containment boundary, polysulfide rubber (35) is first used to chamfer, and then nuclear island paint is applied to form a nuclear island paint coating (32). The nuclear island paint coating (32) covers from the junction of the boundary door frame (37) and the concrete structure of the containment boundary to the point where the nuclear island paint coating overlaps with the concrete structure of the containment boundary.

12. A large fast reactor low-pressure containment system according to claim 7, characterized in that: The containment boundary cover (17) is provided with a double-pass sealing ring and has the conditions for a single-body sealing test; during the installation and commissioning stage of the power plant, the containment boundary cover (17) is movable; after the installation and commissioning of the power plant is completed, the containment boundary cover (17) plate that is not frequently used is connected to the reactor hall (6) bottom plate steel cladding by welding, and a 100% penetration test is performed on the weld surface; a gate valve is provided at the junction of the fuel transfer channel (15) and the reactor hall (6) bottom plate steel cladding, and the fuel transfer channel (15) is connected or closed by controlling the opening and closing of the gate valve.

13. A large fast reactor low-pressure containment system according to claim 1, characterized in that: The ventilation and filtration system comprises an air supply pipeline, an exhaust pipeline, a high-efficiency filter (18), an exhaust fan (19), an exhaust chimney (20), an exhaust isolation valve (21), an air supply isolation valve (22), and an air supply fan (23); air supply pipelines are respectively provided between the reactor top protection cover (5) and the reactor hall (6), and between the reactor pit (7) and the reactor hall (6); an air supply pipeline inlet is provided outside the reactor hall (6), and a first air supply pipeline outlet is provided at the reactor top protection cover (5). In the reactor, a second outlet of the air supply pipeline is arranged in the reactor pit (7); an air supply isolation valve (22) and an air supply fan (23) are arranged on the air supply pipeline; an exhaust chimney (20) is arranged outside the reactor hall (6); an exhaust pipeline is arranged between the reactor pit (7) and the exhaust chimney (20); the outlet of the exhaust pipeline is connected to the inlet of the exhaust chimney (20), and the inlet of the exhaust pipeline is connected to the reactor pit (7); an exhaust isolation valve (21), a high-efficiency filter (18), and an exhaust fan (19) are arranged on the exhaust pipeline.

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