Passive safety system of compact small reactor

Abstract

The invention provides a passive safety system of a compact small reactor, which is characterized in that the reactor and steam generators are mounted in a containment, the steam generators are connected with the reactor, and each steam generator is provided with a passive residual heat removal system; the liquid storage chamber is mounted on the outer wall surface of the containment in a surrounding manner; the heat exchanger assembly is arranged in the liquid storage chamber and is connected with the corresponding steam generator to form a heat exchange cycle, so that steam of the steam generator enters the heat exchanger assembly for heat exchange; at least one air ventilation inlet is formed in the outer wall face of the liquid storage cavity, and external air enters the liquid storage cavity through the air ventilation inlets to conduct air cooling on the heat exchanger assembly. The integrated containment top cooling water tank combined inside and outside is adopted as a cooling water source for cooling the water-cooling heat exchanger and the passive containment, and the water storage chamber is arranged between the containment and the shielding wall, so that unevaporated water on the surface of the containment can be collected, water is saved, and the cooling capacity is enhanced.

Description

Technical Field

[0001] The present invention relates to the field of small reactors, and in particular to a passive safety system for compact small reactors. Background Art

[0002] Among existing technologies, nuclear energy, as a safe, clean, economical, and stable energy source, is a crucial component of my country's efforts to build a clean, low-carbon, safe, and efficient energy system. While my country's nuclear power industry is experiencing rapid growth, safety remains paramount. Safety is not only fully considered in design, but also strictly enforced during the operation of nuclear power units to ensure they remain in a safe state. The third-generation passive large-scale advanced pressurized water reactor (PWR) will become the primary reactor type for China's nuclear power industry. By adopting passive safety concepts, it will simplify the system and improve safety and economic efficiency.

[0003] In recent years, investment in the research and development of small reactors has been increasing both domestically and internationally, driven by their inherent safety, wide application, flexible deployment, and low investment. The development of small reactors places increasing emphasis on safety, advancement, and affordability, with the continuous introduction of new processes, materials, and technologies, and the thorough demonstration of their engineering feasibility, to ensure safer, more economical, and reliable operation.

[0004] Small reactors employ a passive safety design concept, ensuring inherent safety. Due to their low power, small reactors generate less decay heat in the core after an accident, requiring far less heat removal and for a shorter duration than large reactors.

[0005] If an advanced containment cooling system can be designed to reduce the size of the containment, lower the peak pressure of the containment after an accident, and achieve long-term passive heating, the pressure difference between the inside and outside of the containment will be greatly reduced, reducing the driving force for the leakage of fission products outside the containment, ensuring the integrity of the containment, and greatly improving the safety of unit operation.

[0006] In view of this, the inventors of the present application have designed a passive safety system for a compact small reactor in order to overcome the above technical problems. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the defects in the prior art of high peak pressure of the containment after an accident, inability to achieve long-term passive heating, and large pressure difference between the inside and outside of the containment, and to provide a compact passive safety system for small reactors.

[0008] The present invention solves the above technical problems through the following technical solutions:

[0009] A passive safety system for a compact small reactor is characterized in that the passive safety system comprises:

[0010] A containment vessel, a reactor, and at least one steam generator, wherein the reactor and the steam generator are installed in the containment vessel, the steam generator is connected to the reactor, and each steam generator is provided with a passive residual heat removal system;

[0011] a liquid storage chamber, the liquid storage chamber being circumferentially mounted on the outer wall of the containment vessel;

[0012] at least one heat exchanger assembly, the heat exchanger assembly being arranged in the liquid storage chamber and connected to the corresponding steam generator to form a heat exchange cycle, so that the steam from the steam generator enters the heat exchanger assembly for heat exchange;

[0013] At least one air ventilation inlet is provided on the outer wall surface of the liquid storage chamber, and external air enters the liquid storage chamber through the air ventilation inlet to perform air cooling on the heat exchanger assembly.

[0014] According to one embodiment of the present invention, the outlet end of the steam generator is connected to the inlet end of the heat exchanger assembly through an inlet pipe, and the outlet end of the heat exchanger assembly is connected to the inlet end of the steam generator through an outlet pipe, an inlet isolation valve is installed on the inlet pipe, and an outlet isolation valve is installed on the outlet pipe.

[0015] According to one embodiment of the present invention, a coolant tank is provided in the upper area of ​​the liquid storage chamber, and the coolant tank surrounds the periphery of the ventilation outlet of the liquid storage chamber.

[0016] According to one embodiment of the present invention, the heat exchanger assembly includes at least one air-cooled heat exchanger and at least one liquid-cooled heat exchanger connected in series, the air-cooled heat exchanger is located in the liquid storage chamber, the liquid-cooled heat exchanger is located in the coolant tank, the outlet end of the steam generator is connected to the air-cooled heat exchanger, and the liquid-cooled heat exchanger is connected to the inlet end of the steam generator to form a cooling cycle.

[0017] According to one embodiment of the present invention, the air outlet side of each of the air ventilation inlets faces the air-cooling heat exchanger.

[0018] According to one embodiment of the present invention, the passive safety system further includes a passive spray system, and the passive spray system directly sprays the steam space in the containment vessel.

[0019] According to one embodiment of the present invention, the passive spray system includes at least one pressurized water tank, an injection water pipe and a plurality of spray heads. The pressurized water tank is arranged outside the bottom end of the containment shell. The injection water pipe is arranged around the inner wall surface of the containment shell and is connected to the pressurized water tank. The spray heads are installed on the injection water pipe and are located in the top area of ​​the containment shell.

[0020] According to one embodiment of the present invention, a spray injection isolation valve is provided on the injection water pipe, and the spray injection isolation valve is located between the containment shell and the pressurized water tank.

[0021] According to one embodiment of the present invention, the passive spray system further includes a plurality of cooling liquid injection pipes and a cooling liquid injection main pipe. The cooling liquid injection pipes are connected to the coolant tank and converged to the cooling liquid injection main pipe to spray onto the outer surface of the containment shell.

[0022] According to one embodiment of the present invention, a coolant isolation valve is installed on the coolant injection pipe.

[0023] The positive progress effect of the present invention is:

[0024] The passive safety system of the compact small reactor of the present invention adopts an integral containment top cooling water tank with internal and external combinations as the cooling water source for the water-cooled heat exchanger of the secondary side passive residual heat removal system and the passive containment cooling. A water storage chamber is provided between the containment and the shielding wall to collect unevaporated water on the surface of the containment for further cooling the containment through pool boiling heat exchange, thereby saving water and enhancing cooling capacity.

[0025] A pressurized passive spray system is installed outside the containment vessel, reducing steam pressure within the containment vessel after a loss of coolant accident (LOCA) through direct steam-water heat exchange. This structure effectively reduces peak containment pressure after an accident and enables long-term passive heating, significantly improving unit operational safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which like reference numerals represent like features throughout, wherein:

[0027] Figure 1 It is a schematic structural diagram of the passive safety system of the compact small reactor of the present invention.

[0028] Reference numerals

[0029] Containment 10

[0030] Reactor 20

[0031] Steam generator 30

[0032] Liquid storage chamber 40

[0033] Heat exchanger assembly 50

[0034] Air ventilation inlet 41

[0035] Ventilation outlet 42

[0036] First cooling water tank 43

[0037] Second cooling water tank 44

[0038] Air cooling heat exchanger 51

[0039] Liquid-cooled heat exchanger 52

[0040] Import pipeline 31

[0041] Export pipe 32

[0042] Inlet isolation valve 33

[0043] Outlet isolation valve 34

[0044] Pressurized water tank 60

[0045] Injection water pipe 70

[0046] Sprinkler 80

[0047] Spray injection isolation valve 71

[0048] Cooling injection pipe 90

[0049] Cooling injection main pipe 91

[0050] Coolant isolation valve 92

[0051] Shielding Wall 100 DETAILED DESCRIPTION

[0052] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0053] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Reference will now be made in detail to preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to represent the same or similar parts.

[0054] Furthermore, although the terms used in the present invention are selected from well-known and commonly used terms, some terms mentioned in the present specification may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description herein.

[0055] Furthermore, it is required that the present invention be understood not only by the actual terms used but also by the meanings lying behind each term.

[0056] like Figure 1 As shown, the present invention discloses a passive safety system for a compact small reactor, comprising: a containment vessel 10, a reactor 20, and at least one set of cooling circulation systems, wherein the cooling circulation systems are arranged around the reactor 20 (e.g., Figure 1 As shown, two sets of cooling circulation systems are symmetrically arranged on both sides of the reactor 20. Of course, this is only an example, and more sets of cooling circulation systems can be included. The structure of each cooling circulation system is the same. In this application, one cooling circulation system is used as an example for detailed description. The structures of the other cooling circulation systems are the same and will not be described in detail.

[0057] A cooling cycle system includes at least one steam generator 30, a liquid storage chamber 40, and at least one heat exchanger assembly 50. The reactor 20 and the steam generator 30 are installed within the containment vessel 10, and the steam generator 30 is connected to the reactor 20. Each steam generator 30 is equipped with a passive residual heat removal system.

[0058] The liquid storage chamber 40 is mounted around the outer wall of the containment vessel 10. It collects unevaporated water from the surface of the containment vessel 10, which is then used to further cool the containment vessel 10 through pool boiling heat exchange, thus conserving water and enhancing cooling capacity. A heat exchanger assembly 50 is disposed within the liquid storage chamber 40 and connected to the corresponding steam generator 30, forming a heat exchange loop. Steam from the steam generator 30 enters the heat exchanger assembly 50 for heat exchange.

[0059] At least one air ventilation inlet 41 is provided on the outer wall of the liquid storage chamber 40 (e.g., the outer wall is preferably configured as a shielding wall 100). External air enters the liquid storage chamber 40 through the air ventilation inlet 41 to cool the heat exchanger assembly 50. The air ventilation inlet 41 enhances thermal capacity and removes heat through air convection, thereby meeting the cooling requirements of both the heat exchanger assembly 50 and the outer surface of the containment vessel 10.

[0060] A coolant tank is provided in the upper area of ​​the liquid storage chamber 40, and the coolant tank surrounds the periphery of the ventilation outlet 42 of the liquid storage chamber 40. For example, the coolant tank can be a cooling water tank. Figure 1 As shown, the coolant tank in this embodiment is divided vertically by an annular baffle into independent inner and outer tanks, namely, a first cooling water tank 43 and a second cooling water tank 44. The inner second cooling water tank 44 is at a relatively high elevation, resulting in a greater gravity-driven force. This increases the cooling flow rate as a cooling water source for passive containment cooling.

[0061] In this embodiment, the heat exchanger assembly 50 preferably includes at least one air-cooled heat exchanger 51 and at least one liquid-cooled heat exchanger 52 connected in series. The air-cooled heat exchanger 51 is located within the liquid storage chamber 40, below the coolant tank. The liquid-cooled heat exchanger 52 is located within the first cooling water tank 43. The outlet of the steam generator 30 is connected to the air-cooled heat exchanger 51, and the liquid-cooled heat exchanger 52 is connected to the inlet of the steam generator 30, forming a cooling cycle. The outlet side of each air ventilation inlet 41 preferably faces the air-cooled heat exchanger 51.

[0062] Preferably, the outlet of the steam generator 30 is connected to the inlet of the heat exchanger assembly 50 via an inlet pipe 31, and the outlet of the heat exchanger assembly 50 is connected to the inlet of the steam generator 30 via an outlet pipe 32. An inlet isolation valve 33 is installed on the inlet pipe 31, and an outlet isolation valve 34 is installed on the outlet pipe 32.

[0063] Furthermore, the passive safety system further includes a passive spray system that directly sprays the steam space within the containment vessel 10. The passive spray system can reduce the size of the containment vessel 10 and simultaneously reduce the internal pressure of the containment vessel 10 after a loss of coolant accident. This system lowers the steam pressure within the containment vessel 10 after a loss of coolant accident through direct contact heat exchange between steam and water.

[0064] Preferably, the passive spray system includes at least one pressurized water tank 60, an injection water pipe 70 and a plurality of spray heads 80. The pressurized water tank 60 is arranged outside the bottom end of the containment shell 10, the injection water pipe 70 is arranged around the inner wall surface of the containment shell 10 and connected to the pressurized water tank 60, and the spray head 80 is installed on the injection water pipe 70 and is located in the top area of ​​the containment shell 10.

[0065] A spray injection isolation valve 71 may also be provided on the injection water pipe 70 , and the spray injection isolation valve 71 is located between the containment vessel 10 and the pressurized water tank 60 .

[0066] Furthermore, the passive spray system includes multiple cooling liquid injection pipes 90 and a cooling liquid injection main pipe 91. The cooling liquid injection pipes 90 are connected to the second cooling water tank 44 and are fed into the cooling liquid injection main pipe 91 for spraying onto the outer surface of the containment vessel 10. A coolant isolation valve 92 is installed on the cooling liquid injection pipes 90.

[0067] In the above structural description, the connection of the various components is only an exemplary description of the present invention and is not a restrictive description. Other connection methods can also be used and will not be described in detail here.

[0068] According to the above structural description, the working principle of the passive safety system of the compact small reactor of the present invention is:

[0069] When the compact small reactor is operating normally, the inlet isolation valve 33, outlet isolation valve 34, spray injection isolation valve 71, and spray injection isolation valve 71 of the secondary side waste heat removal system of the steam generator 30 are closed, the coolant tank 41, liquid-cooled heat exchanger 52, and air-cooled heat exchanger 51 are in standby state, the second cooling water tank 44 is in standby state, the pressurized water tank 60 is in standby state, and the liquid storage chamber 40 is in a water-free state.

[0070] When a non-loss of coolant accident occurs in the compact small reactor, the inlet isolation valve 33 and the outlet isolation valve 34 of the secondary side waste heat removal system of the steam generator 30 are opened, and the steam in the steam generator 30 enters the liquid-cooled heat exchanger 52 (for example, using cooling water as the coolant) through the inlet pipe 31, and is mainly cooled by the cold water in the first cooling water tank 43, while the water in the tank is heated.

[0071] When the water temperature rises to saturation, the water charge is continuously reduced through boiling. The cooled fluid passes through the air-cooled heat exchanger 51 and is further cooled by air entering through the air ventilation inlet 41. It then enters the steam generator 30 through the outlet pipe 32, completing the cooling cycle and removing the decay heat from the reactor 20. When the decay heat is sufficiently reduced and the water in the first cooling water tank 43 is insufficient to support water cooling, air cooling is primarily achieved through the air-cooled heat exchanger 51 and air entering through the air ventilation inlet 41, achieving a transition from water cooling to air cooling, and from short-term cooling to long-term cooling.

[0072] When a loss of coolant accident occurs in a compact small reactor, a large amount of steam is sprayed into the containment, causing the pressure and temperature inside the containment 10 to continue to rise. At this time, the coolant isolation valve 92 is opened, and the water in the second cooling water tank 44 flows to the outer surface of the containment 10 (for example, a steel containment) through the cooling injection pipe 90 and the cooling injection main pipe 91, removes the heat of the containment 10 by evaporation, and is discharged to the atmosphere through the ventilation outlet 42.

[0073] At the same time, the spray injection isolation valve 71 is opened, and the pressurized fluid in the pressurized water tank 60 supplies water to the spray head 80 in the containment vessel 10 through the injection water pipe 70. The cold water is sprinkled into the steam space in the containment vessel 10, and condensation heat exchange occurs through direct contact between steam and liquid, thereby reducing the pressure in the containment vessel 10.

[0074] As the water in the second cooling water tank 44 forms a liquid film and descends on the outer surface of the containment vessel 10, the unevaporated portion is collected in the liquid storage chamber 40 and used to cool the lower portion of the containment vessel 10. As the core decay heat decreases and the water in the second cooling water tank 44 gradually decreases, the air passing through the air ventilation inlet 41 becomes the primary cooling method for the outer surface of the containment vessel 10, transitioning from water cooling to air cooling, thereby achieving long-term cooling.

[0075] As can be seen from the above, the aforementioned process utilizes a secondary passive residual heat removal system within the steam generator to address non-LOC accidents, and achieves both short-term and long-term core cooling through a series combination of a water-cooled heat exchanger and an air-cooled heat exchanger outside the containment vessel. Air ventilation inlets are provided in the shield wall to enhance air-cooling heat exchange capacity. The passive safety system for the compact small reactor of the present invention utilizes an integrated, internal and external containment top cooling water tank as the cooling water source for the water-cooled heat exchanger and containment cooling. A liquid storage chamber is provided between the containment vessel and the shield wall to collect unevaporated water from the containment vessel surface for further containment cooling via pool boiling heat exchange, thus conserving water while enhancing cooling capacity.

[0076] Furthermore, a pressurized passive spray system installed outside the containment vessel effectively reduces the containment's size and, through direct steam-water heat exchange, reduces steam pressure within the containment vessel after a loss of coolant accident. This structure effectively reduces peak containment pressure after an accident and enables long-term passive heating, significantly improving unit operational safety.

[0077] In summary, the passive safety system of the compact small reactor of the present invention can effectively reduce the peak pressure of the containment after an accident by providing an integral internal and external combined containment top cooling water tank, a water-cooled heat exchanger and an air-cooled heat exchanger, an air vent, a water storage chamber and a pressurized passive spray system, and can also achieve short-term and long-term core cooling, thereby improving the operating safety of the unit.

[0078] For those skilled in the art, the above invention disclosure is intended only as an example and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and amendments to this application. Such modifications, improvements, and amendments are suggested in this application and remain within the spirit and scope of the exemplary embodiments of this application.

[0079] At the same time, this application uses specific terms to describe the embodiments of this application. For example, "one embodiment," "an embodiment," and / or "some embodiments" refer to a certain feature, structure, or characteristic related to at least one embodiment of this application. Therefore, it should be emphasized and noted that "one embodiment," "an embodiment," or "an alternative embodiment" mentioned twice or multiple times in different locations in this specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of this application may be appropriately combined.

[0080] Similarly, it should be noted that, in order to simplify the description of the present disclosure and thus facilitate understanding of one or more embodiments of the invention, the foregoing descriptions of the embodiments of the present disclosure sometimes combine multiple features into a single embodiment, figure, or description thereof. However, this disclosure method does not mean that the subject matter of the present disclosure requires more features than those recited in the claims. In fact, the features of an embodiment may be fewer than the total features of a single embodiment disclosed above.

[0081] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, and such changes and modifications are intended to fall within the scope of the present invention.

Claims

1. A passive safety system for a compact small reactor, characterized in that: The passive safety system includes: A containment vessel, a reactor, and at least one steam generator, wherein the reactor and the steam generator are installed in the containment vessel, the steam generator is connected to the reactor, and each steam generator is provided with a passive residual heat removal system; a liquid storage chamber, the liquid storage chamber being circumferentially mounted on the outer wall of the containment vessel; at least one heat exchanger assembly, the heat exchanger assembly being arranged in the liquid storage chamber and connected to the corresponding steam generator to form a heat exchange cycle, so that the steam from the steam generator enters the heat exchanger assembly for heat exchange; At least one air ventilation inlet is provided on the outer wall surface of the liquid storage chamber, and external air enters the liquid storage chamber through the air ventilation inlet to perform air cooling on the heat exchanger assembly.

2. The passive safety system for a compact small reactor according to claim 1, wherein: The outlet end of the steam generator is connected to the inlet end of the heat exchanger assembly through an inlet pipe, and the outlet end of the heat exchanger assembly is connected to the inlet end of the steam generator through an outlet pipe. An inlet isolation valve is installed on the inlet pipe, and an outlet isolation valve is installed on the outlet pipe.

3. The passive safety system for a compact small reactor according to claim 1, wherein: A coolant tank is provided in the upper area of ​​the liquid storage chamber, and the coolant tank surrounds the periphery of the ventilation outlet of the liquid storage chamber.

4. The passive safety system for a compact small reactor according to claim 3, wherein: The heat exchanger assembly includes at least one air-cooled heat exchanger and at least one liquid-cooled heat exchanger connected in series. The air-cooled heat exchanger is located in the liquid storage chamber, and the liquid-cooled heat exchanger is located in the coolant tank. The outlet end of the steam generator is connected to the air-cooled heat exchanger, and the liquid-cooled heat exchanger is connected to the inlet end of the steam generator to form a cooling cycle.

5. The passive safety system for a compact small reactor according to claim 4, characterized in that: The air outlet side of each of the air ventilation inlets faces the air-cooling heat exchanger.

6. The passive safety system for a compact small reactor according to claim 3, wherein: The passive safety system further includes a passive spray system, which directly sprays the steam space within the containment vessel.

7. The passive safety system for a compact small reactor according to claim 6, wherein: The passive spray system includes at least one pressurized water tank, an injection water pipe and multiple spray heads. The pressurized water tank is arranged outside the bottom end of the containment shell. The injection water pipe is arranged around the inner wall surface of the containment shell and is connected to the pressurized water tank. The spray head is installed on the injection water pipe and is located in the top area of ​​the containment shell.

8. The passive safety system for a compact small reactor according to claim 7, wherein: The injection water pipe is provided with a spray injection isolation valve, and the spray injection isolation valve is located between the containment shell and the pressurized water tank.

9. The passive safety system for a compact small reactor according to claim 6, wherein: The passive spray system further includes a plurality of cooling liquid injection pipes and a cooling liquid injection main pipe. The cooling liquid injection pipes are connected to the coolant tank and are collected into the cooling liquid injection main pipe to spray onto the outer surface of the containment shell.

10. The passive safety system for a compact small reactor according to claim 9, wherein: A coolant isolation valve is installed on the cooling liquid injection pipe.

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