Passive nuclear steam supply system

Abstract

The invention discloses a passive nuclear steam supply system which is characterized in that two ends of a hot-section main pipeline are respectively connected with a reactor pressure vessel and a steam generator, a main pump is vertically connected with the steam generator, two ends of a cold-section main pipeline are respectively connected with the pressure vessel and the main pump, the hot-section main pipeline is provided with a first liquid level pressure tap and a second liquid level pressure tap, and the cold-section main pipeline is provided with a second liquid level pressure tap. The first liquid level pressure tap is located at the bottom of the hot section main pipeline, the second liquid level pressure tap is close to the steam generator and located at the top of the hot section main pipeline, the reactor coolant system further comprises a pressure stabilizer and a surge pipe, one end of the surge pipe is connected to one of the hot section main pipelines, and the other end of the surge pipe is connected to the bottom of the pressure stabilizer. The passive nuclear steam supply system can allow the rated power of the reactor core to be remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of passive nuclear power, and in particular to a passive nuclear steam supply system and a nuclear power plant. Background Art

[0002] The development of nuclear power technology has put forward higher requirements for safety and economy. At present, newly built nuclear power plants in various countries around the world are gradually adopting third-generation nuclear power technology. According to the requirements of the US User Requirements Document (URD) ​​and the European Nuclear Power User Requirements (EUR), the third-generation nuclear power technology should have higher safety, economy, environmental friendliness and reliability. Compared with the second-generation nuclear power technology, the third-generation nuclear power system and configuration are simplified, with higher safety and operating margin, improved equipment performance and component reliability, reduced human errors, significantly improved radiation protection and environmental friendliness, and greatly improved technical and economic performance. In the early stage of the development of the third-generation nuclear power model, the European Pressurized Water Reactor (EPR) developed by Electricité de France and the AP1000 developed by Westinghouse Electric Company of the United States are representative.

[0003] The EPR model adopts an active redundant technology route in terms of safety concept and system configuration, relying on AC power supply, power equipment (main pump), ventilation and refrigeration, and external water sources to achieve accident mitigation and improve the reliability of performing its intended functions under accidents. It increases the multiplicity of the system and improves the reliability of the system by "adding". Although this method can significantly reduce the probability of random failures, it cannot improve the ability to resist common cause failures, nor can it fundamentally reduce human errors and extend the operator's non-intervention time.

[0004] The AP1000 model adopts a passive simplified technical route. It does not rely on external triggers and power sources, but only relies on natural convection, gravity, pre-pressurization, evaporation and condensation and other natural characteristics to achieve safety functions. It achieves safe injection of coolant and removal of decay heat through a layer-by-layer passive system. The system is greatly simplified and has low dependence on the environment, external resources, and human operations. It has strong capabilities to resist internal and external events, common cause failures, human errors, and environmental deterioration.

[0005] However, although the AP1000 model adopts a simplified design concept, its rated power of the unit is only 1000MW, which is still a medium-sized unit. The cost per unit power is at a relatively high level, and it is not economical to build it in areas with high electricity load. The rated power of the EPR model reaches 1750MW, which is suitable for construction in areas with concentrated electricity consumption. Although it adopts a redundant system design, it still has certain cost advantages due to its large capacity. The APR1400 model developed by Korea Hydro & Nuclear Power Corporation has a nominal power of nearly 1400MW and is also favored to a certain extent in the bidding of international nuclear power projects. Therefore, the development of a large-scale passive pressurized water reactor model with high safety and economy will greatly enhance my country's advantage in the competition of third-generation nuclear power.

[0006] Although AP1000 provides a relatively mature nuclear steam supply system, the increase in electric power is not a simple amplification of the system parameters. For example, in the design of the coolant loop, the 1750MW EPR model adopts a four-loop design, the second-generation nuclear power models represented by the 1000MW M310 adopt a three-loop design, and the AP1000 adopts a two-loop design; the number of loops determines the number of steam generators, main pumps, and main pipelines, and the number of interfaces of the pressure vessel, but the number of loops is directly related to the heat transfer capacity of the loops. Constrained by multiple factors such as safety, economy, equipment manufacturing, waste emissions, and the limitation of passive cooling capacity, the nuclear steam supply system needs to be redesigned.

[0007] Therefore, through long-term and extensive research and development work, the applicant has provided a passive nuclear steam supply system and nuclear power plant based on the 193 core, which significantly improved the power generation capacity of the passive system, reduced the core damage frequency and the frequency of large-scale radioactive material release in the safety evaluation indicators, and met the requirements of the third generation of nuclear power. Summary of the invention

[0008] In view of the defects in the prior art, the technical problem to be solved by the present invention is how to provide a passive nuclear steam supply system and a nuclear power plant that meet the requirements of the third generation nuclear power.

[0009] To achieve the above object, the present invention provides a passive nuclear steam supply system based on a 193 core, comprising a reactor body and a reactor coolant system.

[0010] The reactor body includes a reactor pressure vessel, internal components, fuel assemblies, fuel-related components, a control rod drive mechanism, and an integrated top assembly.

[0011] The reactor pressure vessel is a cylindrical structure, comprising a cylinder and a lower head and an upper head at both ends of the cylinder. The lower head and the cylinder are integrally formed, and the upper head is connected to the cylinder in the form of a flange. A nozzle is provided on the cylinder of the reactor pressure vessel.

[0012] The internals are disposed in the reactor pressure vessel, and the internals support the fuel assembly and fuel-related components.

[0013] The number of the fuel assemblies is 193, and the active area length of the fuel assembly is 14 feet.

[0014] The fuel-related components include a control rod assembly, a neutron source assembly, a burnable poison assembly and a resistance plug assembly, and the fuel-related components are distributed between the fuel assemblies.

[0015] The integrated stack top assembly is arranged on the upper head, and the integrated stack top assembly supports the control rod drive mechanism.

[0016] The control rod drive mechanism passes through the upper head, and the control rod drive mechanism drives the control rod assembly.

[0017] The reactor coolant system has two coolant loops, each of which includes a steam generator, two main pumps, a hot section main pipeline, and two cold section main pipelines. The two ends of the hot section main pipeline are respectively connected to the reactor pressure vessel and the steam generator. The main pump is vertically connected to the steam generator. The two ends of the cold section main pipeline are respectively connected to the pressure vessel and the main pump.

[0018] The hot section main pipeline is provided with a first liquid level pressure port and a second liquid level pressure port, wherein the first liquid level pressure port is located at the bottom of the hot section main pipeline, and the second liquid level pressure port is close to the steam generator and located at the top of the hot section main pipeline. The reactor coolant system also includes a pressurizer and a surge pipe, wherein one end of the surge pipe is connected to one of the hot section main pipelines, and the other end of the surge pipe is connected to the bottom of the pressurizer.

[0019] The bottom of the voltage stabilizer is located outside the surge tube and is provided with an electric heating tube.

[0020] A sprayer is provided on the inner side of the upper part of the pressure regulator, and the sprayer is connected to a spray main pipe. The spray main pipe passes through the pressure regulator and is connected to two spray branch pipes. The spray branch pipes are respectively connected to two cold section main pipes. A water seal is provided on the spray main pipe, and spray valves are respectively provided on the spray branch pipes. The spray branch pipes are also provided with needle valves connected in parallel with the spray valves.

[0021] Two groups of pressure relief pipelines are arranged on the top of the pressure stabilizer, each group of the pressure relief pipelines includes a pressure relief main pipe connected to the pressure stabilizer and three parallel pressure relief branch pipes downstream of the pressure relief main pipe, a spring-loaded safety valve is arranged on the pressure relief main pipe, a pipeline with a bursting disc is arranged downstream of the spring-loaded safety valve, the pressure relief branch pipes are respectively provided with first, second and third stage automatic pressure relief valves, the downstream of the pressure relief branch pipes merge into an exhaust pipeline, a vacuum breaker is arranged on the exhaust pipeline, and the pressure relief pipeline is arranged downward from the pressure stabilizer to the first, second and third stage automatic pressure relief valves,

[0022] The reactor body and the reactor coolant system contain reactor coolant, and the absolute pressure of the reactor coolant during operation is 15.5 MPa.

[0023] The rated power of the nuclear steam supply system is not less than 4040MWt.

[0024] Furthermore, it also includes a normal residual heat removal system, which includes a normal residual heat removal pump and a normal residual heat removal heat exchanger. One end of the normal residual heat removal system is connected to one of the hot section main pipelines, and the other end is connected to the reactor pressure vessel. The operation period of the normal residual heat removal system is from hot shutdown to cold shutdown of the nuclear steam supply system.

[0025] Furthermore, it also includes a refueling water tank in the containment, wherein the refueling water tank in the containment stores refueling water, and during refueling, the refueling water floods the cylinder of the reactor pressure vessel.

[0026] Furthermore, a bubbler is provided in the refueling water tank in the containment, and the exhaust line end of the pressure relief line is connected to the bubbler.

[0027] Furthermore, a fourth pressure relief pipeline is connected to one of the hot section main pipelines, and a fourth-stage automatic pressure relief valve is arranged on the fourth pressure relief pipeline, and the fourth-stage automatic pressure relief valve is a bursting valve.

[0028] Furthermore, the cylinder flange and the upper head flange are sealed by a sealing ring, and a leakage monitoring pipeline is provided between the cylinder flange and the upper head flange; the sealing rings are provided in two groups and are concentrically arranged, and there are two leakage monitoring pipelines, one of which is provided between the two groups of sealing rings, and the other is provided on the outside of the sealing rings.

[0029] Furthermore, the top of the pressure vessel is also connected to a venting pipeline.

[0030] Furthermore, a nozzle connecting the voltage stabilizer and the surge tube, and a nozzle connecting the voltage stabilizer and the spray tube are respectively provided with thermal sleeves.

[0031] Preferably, the main pump is a canned motor pump or a wet winding pump.

[0032] Furthermore, the main pump is provided with a phase sensor and at least three vibration sensors, and the vibration sensors are respectively arranged in radial and axial directions of the main pump that are perpendicular to each other.

[0033] Furthermore, the volume of the reactor coolant is 386-390m 3 .

[0034] Furthermore, each group of the fuel assemblies consists of 264 fuel rods, 24 guide tubes, and 1 instrument tube, arranged in a 17×17 pattern.

[0035] The fuel rod comprises a ZIRLO cladding tube and a uranium dioxide ceramic pellet located in the cladding tube. Both ends of the pellet are packaged by Zr-4 end plugs, and the surface of the pellet is coated with a boride coating.

[0036] The average unloading burnup of the fuel assembly is not less than 50000MW·d / tU.

[0037] Preferably, the fuel assembly is uranium-plutonium mixed oxide fuel.

[0038] Furthermore, the control rod drive mechanism provides daily load following control for the nuclear steam supply system.

[0039] Furthermore, the core internals are not provided with neutron shielding plates.

[0040] Furthermore, the design life of the reactor body and the reactor coolant system is 60 years.

[0041] Furthermore, the refueling period of the fuel assembly is 16, 18-24 months, specifically 16, 18, 20, 24 months.

[0042] Furthermore, it also includes a dedicated safety facility, which adopts a passive driving method.

[0043] The dedicated safety facilities include a passive core cooling system, a containment system, a passive containment cooling system, and a hydrogen control system within the containment.

[0044] The passive core cooling system includes a passive safety injection subsystem, which includes a core water makeup tank, a safety injection tank and a refueling water tank in the containment vessel. The core water makeup tank, the safety injection tank and the refueling water tank in the containment vessel are connected to the nozzle of the reactor pressure vessel through a common pressure vessel direct injection line.

[0045] The core water makeup tank stores the first safety water source, the injection tank stores the second safety water source, the refueling water is the third safety water source, and the order of input after an accident is: the first safety water source, the second safety water source, and the third safety water source.

[0046] The passive core cooling system also includes a passive residual heat removal subsystem, which includes a passive residual heat removal heat exchanger located in the refueling water tank in the containment vessel, the inlet end of the hot side of the passive residual heat removal heat exchanger is connected to one of the hot section main pipelines, and the outlet end is connected to one of the steam generators.

[0047] The containment system comprises a steel containment shell, which accommodates the nuclear steam supply system. The inner diameter of the steel containment shell is 43m, the wall thickness of the steel containment shell is 43-55mm, and the steel containment shell can withstand internal pressure.

[0048] The passive containment system includes a passive containment cooling water tank, an air flow channel, and a water diversion hopper, which are arranged outside the steel containment. The passive containment cooling water tank stores a fourth safety water source. The passive containment cooling water tank is higher than the steel containment. The water diversion hopper is connected to the passive containment cooling water tank through a pipeline. The water diversion hopper can provide spray water to the steel containment. The air flow channel is located in the circumferential direction of the outer side of the steel containment, and air can be introduced into the air flow channel.

[0049] The passive containment cooling system further comprises a passive containment cooling auxiliary water tank and a recirculation loop, and the passive containment cooling auxiliary water tank replenishes water to the passive containment cooling water tank through the recirculation loop.

[0050] The hydrogen control system in the containment includes a passive autocatalytic hydrogen recombiner and a hydrogen igniter arranged in the steel containment.

[0051] Furthermore, it also includes: in-core measuring instruments, which are arranged in the reactor pressure vessel and are used to monitor the neutron injection rate and core outlet temperature of the core; out-of-core nuclear measuring instruments, which are arranged outside the reactor pressure vessel and are used to measure the core power; and process measuring instruments, which are used to measure the temperature, pressure, liquid level and flow rate of the reactor coolant system.

[0052] Furthermore, it also includes a protection and safety monitoring system, which collects data from the in-core measuring instruments, out-of-core nuclear measuring instruments, and process measuring instruments to exert control on the passive nuclear steam supply system.

[0053] Furthermore, it also includes a diversified drive system that controls the passive nuclear steam supply system, and the diversified drive system is physically separated from the protection and safety monitoring system.

[0054] The present invention also provides a nuclear power plant, which has a passive nuclear steam supply system based on a 193 core as described above, and also has a steel plate concrete containment, a steam turbine, and a generator. The steel plate concrete containment is located outside the steel containment, and the inlet and outlet of the steam turbine are respectively connected to the outlet and inlet of the secondary side of the steam generator. The steam turbine drives the generator to generate electricity, and the rated power generation power of the generator is not less than 1500MWe.

[0055] The steel plate concrete containment is configured to withstand an impact of a large commercial aircraft.

[0056] Furthermore, a main control room is provided, in which an emergency habitable system is installed, and the emergency habitable system provides a habitable environment for the main control room for 72 hours after an accident.

[0057] Furthermore, a radioactive waste liquid treatment system is provided, and the radioactive waste liquid treatment system is provided with an ion exchange device and a chemical flocculation device.

[0058] The present invention has at least the following beneficial technical effects:

[0059] 1. The nuclear steam supply system of the present invention uses 193 boxes of fuel assemblies with an active area height of 14 feet in the core, which are cooled by two coolant loops, so that the rated power of the core can reach 4040MWt, the gross power of the power plant can reach 1500MWe, and the power plant availability can reach 93%, which significantly improves the economy of the model.

[0060] 2. The present invention adopts non-active dedicated safety facilities, simplifies system configuration, and can alleviate accidents without human operation 72 hours after the accident, reducing the probability of human error.

[0061] 3. The nuclear steam supply system of the present invention has a core design margin of not less than 15%, a core damage frequency of less than 4.02×10-7 / reactor-year, and a probability of large-scale radioactive material release of less than 5.07×10-7 / reactor-year. -8 / reactor year, safety is further improved.

[0062] 4. The nuclear steam supply system of the present invention adopts a mechanical compensation operation strategy and uses control rods to meet the reactivity control requirements of basic load, load following, initial startup, etc., greatly reducing the number of boron adjustments in the basic load operation mode and the amount of boron-containing wastewater in the load following mode, thereby reducing the amount of waste.

[0063] 5. The nuclear power plant of the present invention adopts a double-layer structure of a steel containment shell and a steel plate concrete containment shell, and has the ability to resist the impact of large commercial aircraft.

[0064] 6. The nuclear power plant of the present invention adopts the waste liquid treatment process of ion exchange and chemical flocculation, which greatly reduces the discharge concentration of radioactive waste liquid. For inland sites, the concentration of radioactive effluent can reach no more than 100 Bq / L.

[0065] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is a schematic flow chart of a nuclear steam supply system according to an embodiment of the present invention;

[0067] Figure 2 is a schematic structural diagram of a nuclear steam supply system according to an embodiment of the present invention;

[0068] Figure 3 is a schematic diagram of a reactor body of a nuclear steam supply system according to an embodiment of the present invention;

[0069] Figure 4 is a schematic flow chart of a passive safety injection subsystem according to an embodiment of the present invention;

[0070] Figure 5 is a schematic flow chart of a passive residual heat removal subsystem according to an embodiment of the present invention;

[0071] Figure 6 It is a schematic flow chart of a passive containment cooling system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0072] The following describes the preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0073] In the drawings, components with the same structure are indicated by the same numerical reference numerals, and components with similar structures or functions are indicated by similar numerical reference numerals. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. In order to make the illustration clearer, the thickness of the components is appropriately exaggerated in some places in the drawings.

[0074] The present invention provides a passive nuclear steam supply system based on a 193 core, which adopts a passive accident mitigation design concept. Under the premise of ensuring the passive cooling capacity after an accident, the thermal power of the nuclear steam supply system and the electric power of the nuclear power plant are significantly improved through the integration of fuel design, core design, thermal hydraulic design, equipment design, and system design, thereby improving the economy of nuclear power models, and the safety indicators of the reactor are also significantly improved compared with traditional second-generation nuclear power plants and existing third-generation nuclear power plants.

[0075] like Figure 1 As shown, the nuclear steam supply system of this embodiment is composed of a reactor body and a reactor coolant system. The reactor body is loaded with nuclear fuel, which continuously generates heat through a controllable chain fission reaction; the reactor coolant system is loaded with reactor coolant, which cools the nuclear fuel through the circulation of the reactor coolant, takes away the heat in the reactor body, and the heat brought out by the reactor coolant heats the circulating water on the secondary side to generate steam. The reactor coolant used in the nuclear steam supply system of the present invention is light water.

[0076] The reactor body is composed of at least a reactor pressure vessel, internal components, fuel assemblies, fuel-related assemblies, a control rod drive mechanism, and an integrated top assembly. The reactor pressure vessel provides a high-integrity pressure boundary to accommodate the reactor coolant, the heat-generating core, and the fuel fission products. It is specifically cylindrical and includes three parts: a lower head, a barrel, and an upper head. Both the lower head and the upper head are hemispherical. The lower head and the barrel are integrally forged, and the upper head and the barrel are connected in the form of a flange. Both the barrel and the upper head are provided with flanges. After the barrel and the upper head are connected, the two flanges are sealed by a sealing ring. There are two sets of sealing rings, one inside and one outside, which are concentrically arranged. In this embodiment, the inner diameter of the reactor pressure vessel barrel is 4430 mm.

[0077] The internals are located inside the reactor pressure vessel and consist of lower internals, upper internals and flow guide panels. The internals provide support and positioning for the fuel assembly and related components, provide guidance and flow distribution for the coolant, provide shielding for the reactor pressure vessel, and provide support and guidance for the internal measurement components to ensure the safe and reliable operation of the reactor. Compared with existing nuclear power models, the internals of this embodiment eliminate the neutron shielding plate, thereby reducing the risk of loose parts in the pile; the lower chamber structure eliminates the flow distribution skirt and adopts a removable flow equalizing plate, thereby optimizing the flow distribution performance. In this embodiment, the availability of the internals is not less than 93%.

[0078] The fuel assembly generates heat through nuclear reaction, provides good heat transfer conditions to conduct heat, and is supported by the internal components of the reactor to maintain stability during nuclear reaction. The reactor pressure vessel of this embodiment is loaded with 193 boxes of fuel assemblies, which are arranged in a 15×15 pattern in the core components; the height of the active area of ​​the fuel assembly is 426.72 cm, i.e. 14 feet; the average linear power density of the fuel assembly is 181.0 W / cm.

[0079] Each box of fuel assembly consists of 264 fuel rods and fuel assembly skeletons, arranged in a 17×17 square. The fuel assembly skeleton consists of an upper tube seat, a lower tube seat, 8 intermediate grids, 4 intermediate mixing grids, 1 top grid, 1 bottom grid, 1 protection grid, 24 control rod guide tubes and 1 instrument tube. The fuel rods are composed of ZIRLO cladding tubes and Zr-4 end plugs encapsulating uranium dioxide ceramic pellets. The pellets are cylindrical and made of low-enriched uranium dioxide powder that is cold pressed and sintered to the required density. The fuel rods adopt a monolithic fuel-burnable poison structure, and the surface of the fuel pellets is coated with boride.

[0080] The reactor body of this embodiment can be loaded with uranium dioxide fuel assemblies as well as uranium-plutonium mixed oxide fuel, so that the core has the ability to load MOX.

[0081] There are also fuel-related components in the core components, including control rod assemblies, burnable poison assemblies, neutron source assemblies and resistance plug assemblies. The related components are used to control the reactivity of the fuel assemblies. The fuel assemblies and fuel-related components constitute the core of the reactor. The equivalent diameter of the core active area is 337.10 cm, and the core height-diameter ratio is 1.27.

[0082] The integrated top assembly is installed on the upper head of the reactor pressure vessel. During the shutdown and refueling of the reactor, the top assembly can be lifted, transferred and stored as a whole through integrated operation with the upper head, thereby simplifying the refueling operation, shortening the refueling time and improving the availability of the nuclear power plant. The integrated top assembly is mainly composed of the shroud assembly, control rod drive mechanism, ventilation and cooling system, cantilever suspension components, control rod drive mechanism seismic support structure, top cover hanger, pressure vessel top cover venting system support, etc.

[0083] The control rod drive mechanism is arranged on the integrated reactor top assembly and passes through the upper head. The control rod drive mechanism is used to connect with the control rod assembly, and controls the insertion and lifting of the control rod assembly to control the average temperature of the core, thereby achieving safe start-up of the reactor, regulating the reactor power and shutting down the reactor. In this embodiment, the control rod drive mechanism is a magnetic lifting type.

[0084] The fuel assembly adopts a high-burnup, low-leakage core loading method in both the first cycle and the refueling cycle, which can improve neutron economy and extend the operating life of the reactor pressure vessel. During operation, the refueling cycle is 18-24 months, and it can alternate between 18-month refueling and 16 / 20-month refueling to meet the different refueling time requirements of the power station. Under different refueling strategies, the average burnup of the fuel element after unloading is not less than 50,000MW·d / tU, and the maximum can reach 62,000MW·d / tU.

[0085] The control rod assembly meets the reactivity control requirements in basic load, load following, initial startup, shutdown restart and rapid power reduction modes, and can achieve daily load tracking operation, with the operation strategy of mechanical compensation. This operation strategy can significantly reduce the number of boron adjustments in the basic load operation mode and the amount of boron-containing wastewater in the load following operation mode, and achieve non-adjusted boron load tracking above a certain power in most of the cycle life.

[0086] There are two leakage monitoring pipelines between the reactor pressure vessel cylinder flange and the upper head flange, one between the inner and outer sealing rings, and the other outside the outer sealing ring. The two leakage pipelines share a mother pipe, on which a high-temperature alarm temperature detector is set to monitor the reactor pressure vessel flange seal leakage. When the monitored temperature is higher than the ambient temperature, it indicates that there is a seal leak, triggering a high-temperature alarm.

[0087] The reactor coolant system is connected to the reactor pressure vessel, and the decay heat generated by the core is taken away by driving the coolant to circulate between the reactor coolant system and the reactor pressure vessel. The reactor coolant system includes two cooling loops, which are respectively connected to the reactor pressure vessel. For the convenience of description, the two cooling loops are replaced by loop one and loop two respectively. Loop one and loop two each include at least one steam generator, two main pumps, one hot section main pipeline, and two cold section main pipelines. The reactor coolant flows on the primary side of the steam generator, and the two ends of the hot section main pipeline are respectively connected to the reactor pressure vessel and the steam generator. The two main pumps are directly connected to the steam generator, and the two ends of the two cold section main pipelines are respectively connected to the reactor pressure vessel and one of the main pumps. In this way, after the reactor coolant is heated in the reactor pressure vessel, it enters the primary side of the steam generator through the hot section main pipeline, and after heat exchange through the steam generator, it returns to the reactor pressure vessel through the main pump and the cold section main pipeline to realize circulation; after the secondary side of the steam generator absorbs the heat from the primary side, it generates steam to drive the steam turbine to do work. The main pump provides driving force for the circulation of the reactor coolant.

[0088] The steam generator is a steam generating device that integrates a vertical shell, a U-shaped tube and a steam-water separation device. The main components include a water chamber head, a lower cylinder, an upper cylinder, an upper head, a tube sheet, a water chamber baffle, a tube bundle, and a steam-water separation device. The water chamber head, the lower cylinder, the upper cylinder, and the upper head are connected in sequence to form a steam generator cylinder; the tube sheet is located inside the steam generator near the connection between the water chamber head and the lower cylinder, and divides the internal space of the steam generator into two parts, upper and lower; the tube bundle is a U-shaped tube, and its port passes through the tube sheet; the water chamber baffle is located between the water chamber head and the tube sheet, and divides the space of the water chamber head into two parts, left and right, and separates the two ports of each U-shaped tube in the two compartments of the water chamber head. One side compartment of the water chamber head is equipped with a nozzle connected to the hot section main pipeline, and the other side compartment is equipped with two nozzles connected to the main pump, so that the reactor coolant flowing from the hot section main pipeline enters one side of the water chamber head, and then enters the other side of the water chamber head after passing through the U-shaped tube bundle, and returns after passing through the main pump and the cold section main pipeline. The steam-water separation device is located on the secondary side of the tube bundle, including a primary separator and a dryer, which separates steam and water from the steam generated on the secondary side. A steam outlet is provided at the top of the upper head, and a water inlet is provided on the side of the upper cylinder to realize the secondary side steam-water circulation.

[0089] In addition to the above main components, the steam generator also includes auxiliary components such as tube support plates and anti-vibration strips to maintain the stability of the tube bundle in the steam generator.

[0090] In this embodiment, the heat transfer area of ​​a single steam generator is 14666.5m 2 The allowable pipe plugging rate is 10%, the primary side operating gauge pressure is 15.4MPa, and the thermal design flow rate of the primary side reactor coolant is 41206m 3 / h, thereby achieving a heat transfer of 2029MW for a single steam generator.

[0091] The main pump is used to pump the reactor coolant to circulate between the core, coolant loop and steam generator. Two main pumps are hung on the lower head of each steam generator. The inlet nozzle of the main pump is directly connected to the lower head of the steam generator. The two main pumps on each steam generator run in the same direction. The main pump is vertical and can be a canned motor pump or a wet winding motor pump. Under the best estimated flow rate, the flow rate of a single main pump is 21642m 3 / h.

[0092] The motor and all rotating parts of the canned pump are contained in a pressure vessel, which consists of a pump casing, heat shield ring, stator top cover, stator flange and casing assembly, stator bottom cover, as well as pipes, flanges, and external heat exchanger tube sides; the canned pump drive motor is a vertical, water-cooled, squirrel-cage induction motor with a canned rotor and stator, with a flywheel on the motor side. The motor and all rotating parts of the wet-winding pump are contained in a pressure vessel, which consists of a pump casing, heat shield, main flange bolts and nuts, motor casing, bearing bracket, thrust bearing box, as well as pipes, flanges, and external heat exchanger tube sides, with the stator and rotor in direct contact with the reactor coolant; the motor of the wet-winding pump is a vertical, water-cooled, squirrel-cage wet-winding induction motor, with a flywheel on the motor side.

[0093] The main pump is suspended on the lower head of the steam generator and will generate certain vibrations during operation. Therefore, a vibration monitoring device is installed on each main pump. Specifically, the vibration monitoring device includes 5 speed sensors and 1 phase sensor. The 5 speed sensors are used to measure radial vibrations in the X direction (2), radial vibrations in the Y direction (2) and axial vibrations in the Z direction (1); the phase sensor is used to output the rotation frequency and is used in conjunction with the speed sensor. When the speed sensor detects different vibration values, different alarms will be triggered to ensure the safety of the main pump operation.

[0094] Relative to the reactor pressure vessel, loop one and loop two both adopt a two-in-one-out setting, and loop one and loop two are arranged symmetrically relative to the reactor pressure vessel. In each coolant loop, the hot section main pipeline is located between the cold section main pipelines, and the center elevation of the cold section main pipeline is 445mm higher than the center elevation of the hot section main pipeline. In this way, when the reactor coolant in the cold section main pipeline enters the reactor pressure vessel, it naturally sinks according to the density difference, which is convenient for the mixing of the reactor coolant. The outer diameter of the hot section main pipeline is 1088mm, the wall thickness is 94mm, the gauge pressure during normal operation is 15.7MPa, and the temperature during operation is 324℃; the outer diameter of the cold section main pipeline is 795mm, the wall thickness is 72.5mm, the gauge pressure during normal operation is 16.2MPa, and the temperature during operation is 291℃. Under the best estimated flow rate, the flow velocity in the hot section main pipeline and the cold section main pipeline is reduced, which alleviates the problem of accelerated corrosion of the flow velocity in the pipeline during long-term operation.

[0095] On the main pipeline of the hot section of one of the two coolant loops, which is defined as loop 1 in this embodiment, a surge tube and a pressurizer are connected. The pressurizer is the balance point for the liquid and steam in the reactor coolant system to maintain a saturated state. It controls the pressure of the reactor coolant system in steady-state operation and transiently in the power plant; in accident conditions, it cooperates with other facilities to control the pressure change of the reactor coolant system within the allowable range; in major accident conditions, it provides overpressure or low pressure protection to prevent damage to the core or other equipment.

[0096] The pressure stabilizer is a cylindrical pressure vessel, consisting of an upper head, a cylinder and a lower head. The upper head is a hemispherical shell, on which there is a spray pipe and two safety pressure relief pipes, and a sprayer is also provided inside the head. The lower head is a hemispherical shell, with a surge pipe connected in the center, and electric heaters are provided around the surge pipe, each of which can be replaced separately.

[0097] A spray branch pipe is connected to each of the two cold section main pipes of loop one, and a spray valve is provided on each of the spray branch pipes. The spray branch pipes are connected to the spray pipe of the upper head of the pressurizer after merging into the spray main pipe, forming the spray subsystem of the pressurizer. When the main pump is running, the pressure difference generated at the connection between the cold section main pipe and the spray branch pipe and the connection between the hot section main pipe and the surge pipe acts as a driving force to drive the spray flow from the cold section main pipe into the upper head, so that the supercooled atomized water is sprayed into the pressurizer to suppress the pressure increase. A needle valve is arranged in parallel with each of the two spray branches and the spray valve, allowing a continuous small bypass flow to pass through the spray pipe and the surge pipe of the pressurizer when the spray valve is closed, thereby preventing the overcooling of the spray line and the surge pipe when the spray is not needed to control the pressure during normal operation, reducing thermal stress and thermal shock when the main spray valve is opened or the coolant in the surge pipe is caused by transient inflow and outflow, and helping to maintain the uniformity of water chemistry and temperature in the pressurizer. A water seal is arranged on the spray main pipe to prevent steam from accumulating and returning to the spray valve.

[0098] A safety valve is provided on each of the two pressure relief pipelines on the upper head of the pressurizer to provide overpressure protection for the reactor coolant system. The safety valve is a spring-type safety valve. When the pressure in the pressurizer exceeds the set value of the safety valve, the safety valve opens to release the pressure. A short pipe with a bursting disc is provided on the downstream pipeline of the outlet of the safety valve to provide a closed collection space for the condensate leaking from the valve. Compared with the nuclear power plants in service, the inlet pipeline of the safety valve in this embodiment is not provided with a water seal, thereby avoiding the drift of the pressure setting value. Three parallel pressure relief branches are provided on the pressure relief pipeline, and an automatic pressure relief valve is provided on each of the three pressure relief branches, namely, the first-stage automatic pressure relief valve, the second-stage automatic pressure relief valve, and the third-stage automatic pressure relief valve; the downstream of the three-stage automatic pressure relief valve merges into an exhaust pipeline, and a vacuum breaker is provided on the exhaust pipeline to ensure that the pressure of the discharge pipe remains at atmospheric pressure after the valve is released, and to prevent the steam from condensing in the pipeline after the valve is discharged to generate a vacuum, thereby siphoning water. The pressure relief line is arranged downward from the pressure stabilizer to the first valve on the pressure relief line to form a cold water seal in front of the first valve to minimize steam leakage during normal power operation.

[0099] The surge pipe connects the hot section main pipeline and the pressurizer. When the coolant density in the reactor coolant system changes, the expanding or contracting reactor coolant flows into or out of the pressurizer through the surge pipe. The electric heater heats the supercooled liquid entering the pressurizer, heating and vaporizing part of the water in the pressurizer to control the pressure drop. The surge pipe is a nearly spiral structure to make it flexible enough to adapt to changes in the reactor coolant temperature; the surge pipe has a continuous downward slope from the pressurizer nozzle to the hot section main pipeline, thereby minimizing the thermal stratification in the surge pipe and preventing the accumulation of sewage in the pipeline.

[0100] In normal operation transient state, in order to reduce the high thermal stress caused by the rapid change of fluid temperature, the surge pipe nozzle and the stabilizer spray pipe nozzle at the bottom of the stabilizer are provided with thermal sleeves to avoid excessive thermal stress.

[0101] A vent pipeline is provided on the top of the reactor pressure vessel, and a stack top vent valve is provided on the vent pipeline. The reactor coolant is discharged through the stack top vent valve to prevent a large amount of coolant from being injected into the pressure vessel and causing the pressurizer to overflow.

[0102] In this embodiment, the inner diameter of the stabilizer is 2696 mm, the height is about 14574 mm, and the minimum internal volume is 70.8 m 3 The rated total power of the electric heater is 1950kW and the designed spray flow rate is 205m 3 / h, the set pressure of the safety valve is 17.2MPa. Including the volume of the pressurizer and surge pipe in the cold state, the total volume of the reactor coolant system is 390m3 when equipped with a wet winding pump. 3 , 386m when equipped with shielded pump 3 .

[0103] The above nuclear steam supply system has 193 boxes of 14-foot fuel assemblies and is cooled by two cooling loops. The core power exceeds 4000MWt and the rated power can reach 4040MWt. The core design margin is greater than or equal to 15%, which significantly improves the core power. The two-loop reactor coolant system also reduces the number of equipment and the space occupied by equipment, which significantly improves the economy of the model.

[0104] Two pressure tapping ports are provided on the hot section main pipe for connecting the liquid level transmitter to monitor the liquid level of the reactor coolant system during the half-filling period after shutdown. One pressure tapping port is located at the bottom of the hot section main pipe, and the other pressure tapping port is located at the top of the hot section main pipe and as close to the steam generator as possible. The redundant setting of the hot section liquid level measurement channel pipe enables continuous monitoring of the reactor coolant level during the half-pipe operation, improving the reliability of monitoring.

[0105] During the shutdown period, in order to cool the core, the nuclear steam supply system of this embodiment is provided with a normal residual heat removal system, which includes a normal residual heat removal pump, a normal residual heat removal heat exchanger and related pipelines and valve components. The inlet end of the normal residual heat removal system is connected to the hot section main pipeline, and the outlet end is connected to the reactor pressure vessel. During the shutdown period, the reactor coolant is transported to the normal residual heat removal heat exchanger for cooling through the normal residual heat removal pump, and the cooled reactor coolant is returned to the reactor pressure vessel. The normal residual heat removal system is an active system, which cools the core only during the shutdown period.

[0106] The reactor pressure vessel is located in the reactor cavity, and the cylinder, lower head and internal components of the reactor pressure vessel are submerged during refueling. To achieve refueling, the nuclear steam supply system of this embodiment is provided with a refueling water tank in the containment, and refueling water is stored in the refueling water tank in the containment. When refueling is performed, the refueling water in the refueling water tank in the containment is transported to the reactor cavity, and after refueling is completed, the refueling water is transported back to the refueling water tank in the containment.

[0107] A bubbler is installed in the refueling water tank in the containment. The exhaust pipelines after the first, second and third stage automatic pressure relief valves are connected to the bubbler, and water and steam are discharged into the refueling water tank in the containment through the bubbler. By opening these automatic pressure relief valves, the steam and water in the pressurizer are discharged to the outside, and the pressure of the reactor coolant system can be reduced step by step. The vacuum breaker on the pressure relief pipeline can prevent water from being siphoned from the bubbler in the refueling water tank in the containment.

[0108] The hot section main pipeline of loop 1 is also connected to a fourth-stage pressure relief pipeline, which is provided with a bursting valve, and the end of the fourth-stage pressure relief pipeline faces the gas space. After the accident, the bursting valve of the fourth-stage pressure relief pipeline opens, reducing the pressure of the reactor coolant system. The bursting valve is a valve driven by gunpowder, which is used for one-time operation and is normally closed. After receiving the start signal, the gunpowder is ignited, causing the valve to open, and the fourth-stage pressure relief pipeline provides pressure relief.

[0109] During normal shutdown, the decay heat of the core is removed through the active normal residual heat removal system. Under accident conditions, dedicated safety facilities are used to limit, control, mitigate and terminate accidents, maintain the safety of the core, and maintain the public's radioactive exposure level within the specified limits. Dedicated safety facilities use non-passive methods to achieve their functions and do not rely on active components to prevent and mitigate accidents; specific non-passive measures include gravity, natural circulation, energy storage devices, check valves, and non-circulating power valves. Dedicated safety facilities specifically include passive core cooling systems, containment systems, passive containment cooling systems, and hydrogen control systems in containment.

[0110] The passive core cooling system is used to discharge the core decay heat after an accident, reduce the temperature of the fuel cladding, and reduce the release of radioactive materials into the environment. It can be specifically divided into a passive safety injection subsystem and a passive core decay heat discharge subsystem.

[0111] The passive safety injection subsystem is composed of at least two core water supply tanks, two safety injection tanks, a refueling water tank in the containment, and related pipes and valves. The core water supply tank, safety injection tank, refueling water tank in the containment, and the containment recirculation flow channel are injected into the direct injection nozzle of the reactor pressure vessel through two common reactor pressure vessel direct injection pipelines. After the hypothetical loss of coolant accident occurs, the pressure of the reactor coolant system decreases, the safety facility drive causes the reactor to shut down and inject safely, the safety facility drive signal triggers the main pump to shut down and open the isolation valve at the outlet of the core water supply tank, and the core water supply tank provides high-pressure injection; when the pressure drops to a certain platform, the installation box starts to inject; when the valve of the fourth-level pressure relief pipeline is activated, the injection burst valve of the refueling water tank in the containment is activated; finally, the check valve on the injection pipeline of the refueling water tank in the containment is opened, and the refueling water tank in the containment provides gravity injection flow. After a serious accident, the electric valve and the burst valve on the recirculation injection line open, allowing the water in the refueling water tank inside the containment to flood the outer surface of the reactor pressure vessel, providing cooling for the molten core inside the reactor pressure vessel.

[0112] The core water tank provides the first safety water source. It is a cylindrical vertical container with a total volume of 85m 3 The injection tank provides a second safe water source. It is a spherical container with a total volume of 78.6m 3 , water volume is 66.4m 3 The refueling water in the refueling water tank in the containment is the third safety water source, and its minimum water volume is 2686.9m 3 .

[0113] The passive core decay heat removal subsystem includes a passive residual heat removal heat exchanger and related valves and pipelines. The passive residual heat removal heat exchanger is located in the refueling water tank inside the containment. The inlet pipeline is connected to a hot section main pipeline, and the outlet pipeline is connected to the cold section chamber of the steam generator. After the accident, the passive residual heat removal heat exchanger automatically starts. After the main pump is tripped, the passive residual heat removal heat exchanger operates under natural circulation conditions to remove core decay heat. The design heat exchange capacity of the passive residual heat removal heat exchanger is 75.9MW.

[0114] The containment system consists of a steel containment and mechanical penetrations, valves, and pipelines on the steel containment. The above-mentioned nuclear steam supply system is located inside the steel containment, except for the normal waste heat removal pump, normal waste heat removal heat exchanger, and some pipelines and valves of the normal waste heat removal system. A closed space is formed inside the steel containment to ensure integrity under accident conditions to provide a barrier to prevent the leakage of radioactive products. When the reactor coolant pipeline or the secondary side pipeline of the containment system ruptures at both ends, the peak pressure inside the steel containment will not exceed the design pressure value. The steel containment includes a head and a cylinder. The inner diameter of the cylinder is 43m, the thickness of the head is 43mm, the wall thickness of the cylinder is mostly 52mm, the thickness of the bottom circle of the cylinder is 55mm, and the free volume inside the steel containment is 7.5×10 4 m 3 .

[0115] The refueling water tank in the containment is set inside the steel containment, and the passive residual heat removal heat exchanger is placed in the refueling water tank in the containment. When the passive residual heat removal heat exchanger is in operation after an accident, the coolant flowing through the core enters the primary side of the passive residual heat removal heat exchanger and transfers the heat to the secondary side. The secondary side directly contacts the water in the refueling water tank in the containment. The water in the refueling water tank in the containment evaporates after being heated, and the water vapor rises to the inner wall of the upper steel containment, liquefies after being cooled, and transfers the heat to the steel containment. A condensation reflux device is provided on the steel containment to return the condensate to the refueling water tank in the containment, realizing long-term circulation cooling in the steel containment.

[0116] The passive containment cooling system transfers the heat in the atmosphere of the steel containment to the external environment, limits and reduces the temperature and pressure in the containment after the loss of coolant accident or the rupture of the main steam or main water supply pipeline in the steel containment, so as to maintain the atmospheric pressure of the steel containment within the design limit to ensure the integrity of the steel containment. The passive containment cooling system includes at least one passive containment cooling water tank, a cooling water delivery channel for draining water to the containment, an air flow channel located around the outer side of the steel containment, a cofferdam and a water diversion bucket for water distribution in the steel containment, the passive containment cooling water tank is located higher than the steel containment, the cofferdam and the water diversion bucket are located above the steel containment, the passive containment cooling water tank is connected to the water diversion bucket through a pipeline, the water in the passive containment cooling water tank is sprayed on the outer wall of the steel containment through the water diversion bucket under the action of gravity, absorbs the heat transferred by the steel containment and is heated to become steam, which is carried out with the air in the air flow channel to achieve cooling of the steel containment.

[0117] The passive containment cooling water tank stores the fourth safety water source, with a rated available volume of 3700m 3Within 72 hours after the design basis accident, the passive containment cooling system discharges the heat in the containment in a passive manner without external personnel intervention. In another embodiment, the passive containment cooling system is further provided with a passive containment cooling auxiliary water tank and a recirculation pipeline. After 72 hours, the water of the passive containment cooling auxiliary water tank is transported to the passive containment cooling water tank through the recirculation pipeline for continuous cooling.

[0118] The hydrogen control system in the containment includes a hydrogen monitoring subsystem, a hydrogen recombination subsystem and a hydrogen ignition subsystem. The hydrogen monitoring subsystem includes three hydrogen sensors located in the dome area of ​​the steel containment for monitoring the hydrogen concentration; the hydrogen recombination subsystem includes a passive autocatalytic hydrogen recombination device for handling the slowly generated hydrogen expected under the design basis loss of coolant accident; the hydrogen ignition subsystem includes a hydrogen igniter, which is started by the operator before the hydrogen concentration reaches the flammable limit.

[0119] The nuclear steam supply system with the above-mentioned dedicated safety facilities has achieved a power plant availability rate of 93% and a core damage frequency of less than 4.02×10 -7 / reactor year, the frequency of large-scale radioactive material release is less than 5.07×10 -8 / Stack year, the economy and safety of the model are further improved.

[0120] The nuclear steam supply system of this embodiment also includes instruments and control systems, which collect physical parameters such as temperature, pressure, flow, liquid level, neutron injection rate, etc. in the system, and send control instructions to the equipment after signal processing, mathematical operation, and logical judgment. The measuring instruments include process measurement, external core measurement, and internal measurement instruments, and the control system includes power plant control system, reactor protection and safety monitoring system, and diversified drive system.

[0121] Process measurement instruments are used to measure most thermal parameters such as temperature, pressure, liquid level, flow, etc. They are set according to the needs of parameter monitoring. The collected data is transmitted to the power plant control system, reactor protection and safety monitoring system or diversified drive system. The measurement channels adopt multi-channel redundant settings.

[0122] The nuclear instrument outside the reactor measures the core power information to ensure continuous monitoring of the reactor power. The nuclear instrument outside the reactor provides the neutron injection rate signal to the reactor protection and safety monitoring system. When high neutron injection rate and high change rate occur, the reactor protection and safety monitoring system triggers the reactor shutdown, providing startup and overpower protection for the reactor.

[0123] The in-core measurement system monitors the neutron injection rate at various locations in the core and the core outlet temperature. All neutron injection rate signals are sent to the core online monitoring system to form a three-dimensional distribution of core power and support core operation optimization.

[0124] The power plant control system is used to maintain the normal operation of the power plant and prevent the reactor from deviating to an unsafe state. During power operation, the power plant control system controls the state of the reactor control rods, valves, pumps, heaters and other equipment, adjusts the parameters of the reactor and reactor coolant system, and maintains constant thermal power; it maintains the equipment and system working under normal conditions, and the power plant parameters remain stable or change smoothly within the specified limits, to prevent the power plant from needing an emergency shutdown.

[0125] The reactor protection and safety monitoring system provides necessary protection and supervision for reactor control during normal operation, so that safety functions can be triggered and the power plant can be kept in a safe shutdown state under abnormal, design basis events and accident conditions. When the power plant parameters reach the shutdown setting value, the reactor protection and safety monitoring system automatically triggers the reactor emergency shutdown; drives the dedicated safety facilities to mitigate the consequences of the design basis accident.

[0126] The diversified control system is a backup for the reactor protection and safety monitoring system and is physically separated from the protection and monitoring system. It does not use the same measuring instruments, computing and processing devices, indicators, drive devices and power supplies, and has no interconnected circuits. The diversified drive system mitigates the consequences of expected transients that fail to shut down the reactor in an emergency, reduces the probability of core damage caused by hypothetical common failures of the protection and monitoring systems in probabilistic safety assessments, and prevents overpressure failure of the containment after core melting.

[0127] The present invention also provides a nuclear power plant, which adopts the above-mentioned passive nuclear steam supply system based on the 193 core, and is also provided with a steel plate concrete containment, a steam turbine, and a generator. The steel plate concrete containment is located outside the steel containment to form a double-layer containment structure. The air inlet and exhaust port of the steam turbine are respectively connected to the steam outlet and water supply port of the steam generator, and the steam turbine is coaxially connected to the generator. In this way, the steam generated by the secondary side of the steam generator enters the steam turbine, drives the steam turbine to do work, and the steam turbine then drives the rotor of the generator to rotate, thereby generating electricity.

[0128] The steam turbine is a half-speed, single-shaft, four-cylinder, six-exhaust, condensing steam turbine equipped with two steam-water separation reheaters. The steam flow at the main steam valve inlet is 7733t / h, the steam absolute pressure is 5.78MPa, the steam temperature is 273.2℃, the unit rated speed is 1500r / min, the unit rated output is 1534MW, and the total gross power of the power plant is 1500MWe.

[0129] The steel plate concrete containment is located outside the steel containment, with a personnel passageway between them. The passive containment cooling water tank is located on the top of the steel plate concrete containment to achieve spraying by gravity. The steel plate concrete containment is provided with an air inlet in the circumference near the upper position to introduce air into the air flow channel of the passive containment cooling system. The thickness of the steel plate concrete containment reaches 1.1m, which has the ability to withstand the impact of large commercial aircraft.

[0130] The nuclear power plant of this embodiment is also provided with a main control room. The main control room is equipped with a digital instrumentation and control platform, which integrates the power plant control system, protection and safety monitoring system, diversified drive system and other instrumentation and control systems to realize the monitoring and control of the nuclear power plant. An emergency habitability system is installed in the main control room to provide breathable air for the main control room personnel and limit the temperature rise in the area, thereby ensuring the habitability of the main control room after an accident. The emergency habitability system consists of an emergency air storage tank and related pipelines, valves and instruments, including an air supply storage tank module and a main air supply pipeline and a backup air supply pipeline leading to the main control room. The air supply storage tank can hold enough compressed air to provide 111m 3 / h to supply air to the main control room for at least 72 hours.

[0131] The nuclear power plant of this embodiment is also equipped with a radioactive waste liquid treatment system. The radioactive waste liquid treatment system is provided with an ion exchange sequence and a chemical flocculation process, thereby further reducing the discharge concentration of the radioactive waste liquid, so that the concentration of radioactive effluent at the coastal site does not exceed 1000Bq / L, and the concentration of radioactive effluent at the inland site does not exceed 100Bq / L, thereby greatly reducing the discharge amount of radioactive waste liquid.

[0132] The preferred specific embodiments of the present invention are described in detail above. It should be understood that ordinary technicians in the field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A passive nuclear steam supply system, characterized in that: Including the reactor body and the reactor coolant system, The reactor coolant system has two coolant loops, each of which includes a steam generator, two main pumps, a hot section main pipeline, and two cold section main pipelines. The two ends of the hot section main pipeline are respectively connected to the reactor pressure vessel and the steam generator. The main pump is vertically connected to the steam generator. The two ends of the cold section main pipeline are respectively connected to the pressure vessel and the main pump. The hot section main pipeline is provided with a first liquid level pressure port and a second liquid level pressure port, wherein the first liquid level pressure port is located at the bottom of the hot section main pipeline, and the second liquid level pressure port is close to the steam generator and located at the top of the hot section main pipeline. The reactor coolant system further comprises a pressurizer and a surge pipe, one end of the surge pipe is connected to one of the hot section main pipes, and the other end of the surge pipe is connected to the bottom of the pressurizer. The reactor body and the reactor coolant system contain a reactor coolant.

2. The passive nuclear steam supply system according to claim 1, characterized in that: The passive nuclear steam supply system also includes a normal residual heat removal system, which includes a normal residual heat removal pump and a normal residual heat removal heat exchanger. One end of the normal residual heat removal system is connected to one of the hot section main pipelines, and the other end is connected to the reactor pressure vessel. The operation period of the normal residual heat removal system is from hot shutdown to cold shutdown of the nuclear steam supply system.

3. The passive nuclear steam supply system according to claim 1, characterized in that: The passive nuclear steam supply system further comprises a refueling water tank in the containment vessel, wherein the refueling water is stored in the refueling water tank. During refueling, the refueling water floods the cylinder of the reactor pressure vessel.

4. The passive nuclear steam supply system according to claim 3, characterized in that: A bubbler is provided in the refueling water tank in the containment, and the exhaust line end of the pressure relief line is connected to the bubbler.

5. The passive nuclear steam supply system according to claim 4, characterized in that: A fourth pressure relief pipeline is also connected to one of the hot section main pipelines, and a fourth-stage automatic pressure relief valve is arranged on the fourth pressure relief pipeline. The fourth-stage automatic pressure relief valve is a bursting valve.

6. The passive nuclear steam supply system according to claim 5, characterized in that: The passive nuclear steam supply system also includes dedicated safety facilities, which are driven passively and include a passive core cooling system. The passive core cooling system includes a passive safety injection subsystem. The passive safety injection subsystem includes a core water makeup tank, a safety injection tank and the refueling water tank in the containment vessel. The core water makeup tank, the safety injection tank and the refueling water tank in the containment vessel are connected to the nozzle of the reactor pressure vessel through a common pressure vessel direct injection line.

7. The passive nuclear steam supply system according to claim 6, characterized in that: The core water makeup tank stores the first safety water source, the injection tank stores the second safety water source, the refueling water is the third safety water source, and the order of input after an accident is: the first safety water source, the second safety water source, and the third safety water source.

8. The passive nuclear steam supply system according to claim 6, characterized in that: The passive core cooling system also includes a passive residual heat removal subsystem, which includes a passive residual heat removal heat exchanger located in the refueling water tank in the containment vessel, the inlet end of the hot side of the passive residual heat removal heat exchanger is connected to one of the hot section main pipelines, and the outlet end is connected to one of the steam generators.

9. The passive nuclear steam supply system according to claim 6, characterized in that: The dedicated safety facilities also include containment systems and passive containment systems. The containment system comprises a steel containment shell, wherein the steel containment shell contains the nuclear steam supply system. The passive containment system includes a passive containment cooling water tank, an air flow channel, and a water diversion hopper, which are arranged outside the steel containment. The passive containment cooling water tank stores a fourth safety water source. The passive containment cooling water tank is higher than the steel containment. The water diversion hopper is connected to the passive containment cooling water tank through a pipeline. The water diversion hopper can provide spray water to the steel containment. The air flow channel is located in the circumferential direction of the outer side of the steel containment, and air can be introduced into the air flow channel.

10. The passive nuclear steam supply system according to claim 9, characterized in that: The passive containment cooling system further comprises a passive containment cooling auxiliary water tank and a recirculation loop, and the passive containment cooling auxiliary water tank replenishes water to the passive containment cooling water tank through the recirculation loop.

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