Primary circuit safety control system and control method

Abstract

The application provides a one-loop safety control system and a control method. The control system comprises a pressure source, a receiving unit, a switching unit and a balancing unit. One end of the pressure source is connected with the one-loop through the balancing unit. The pressure source is also connected with the receiving unit and the switching unit respectively. One end of the switching unit is connected with the one-loop, and the other end is connected with the receiving unit. The balancing unit comprises a shell. The shell is provided with a first channel and a second channel. The first channel and the second channel are provided with a control mechanism. The first channel is connected with the pressure source. The second channel is connected with the one-loop. The control mechanism is used for controlling the on-off between the first channel and the second channel, so as to meet the overpressure protection of the pressure source to the one-loop side, the automatic pressure compensation of the one-loop to the pressure source side and the pressure maintaining function of the pressure source. The one-loop safety control system simplifies the structure configuration of the one-loop side control system and meets the space arrangement requirement of the small reactor.

Description

Technical Field

[0001] This invention relates to the field of one-loop safety control technology, specifically to a one-loop safety control system and control method. Background Technology

[0002] As nuclear power plant designs tend to be simplified and miniaturized, equipment connected to the primary loop must not only perform pressure boundary isolation functions, but also accident mitigation functions, including the ability of related equipment to effectively operate to meet the requirements of primary loop depressurization and water replenishment after an accident.

[0003] Equipment connected to the primary circuit may require a power source to perform its functions and trigger equipment operation after an accident. This power source can be electric, pneumatic, hydraulic, or other types. For small nuclear power plants, the containment space is limited, necessitating a simplified power source design to meet layout requirements.

[0004] Among them, electric motors require safety-grade cables to be installed inside the containment, which not only makes the electric motors too large to be easily installed, but also presents the challenge of adding new safety-grade cable penetrations; pneumatic motors, in addition to having larger drive units, also have reliability issues with the supporting air supply system.

[0005] Therefore, for small reactors, designers generally prefer to use hydraulic power sources for drive.

[0006] However, for hydraulic power sources, whether designed as a compact integrated unit or a separate unit, two issues need to be considered: pressure reduction due to pressure source leakage and the issue of pressure replenishment. Traditional pipe connection designs and active capacity water replenishment methods, while utilizing existing pumps and water sources, require upgrading the active equipment to a safety level, which presents certain shortcomings in terms of economy and space occupation. Moreover, such system designs are complex, occupy a large space, are not conducive to miniaturization and the development of new reactors, and lack technological advancement.

[0007] Another problem is that because the equipment that operates after an accident is connected to the primary circuit, the pressure source used to maintain equipment balance is small in size due to miniaturization requirements. Affected by the high temperature of the primary circuit, the pressure source will quickly transfer heat from the primary circuit to itself, causing its temperature to rise rapidly. During system transient changes, the pressure source is prone to overpressure. Overpressure can severely damage the equipment and even lead to equipment failure.

[0008] Traditional methods involve setting up overpressure lines or directly installing safety relief valves on the pressure chamber to discharge fluid into the waste liquid system or containment. However, setting up overpressure lines and safety relief valves is not only complex, but also, due to the limited space in the chamber, may cause instantaneous pressure loss in the chamber during discharge, which cannot be quickly restored. This can lead to unstable system operation or even equipment malfunction, making it difficult to mitigate abnormal transient conditions and escalating into an accident condition with a primary circuit failure.

[0009] Based on this, the inventors of this application propose a single-loop safety control system and control method to solve one or more of the above-mentioned technical problems. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to overcome the shortcomings of traditional one-loop control systems in that they cannot meet the functions of pressure source overpressure protection, automatic pressure compensation and pressure maintenance, and to provide a one-loop safety control system and control method.

[0011] The present invention solves the above-mentioned technical problems through the following technical solution:

[0012] This invention provides a one-loop safety control system, characterized in that it includes:

[0013] The system comprises a pressure source, a receiving unit, a switching unit, and a balancing unit. One end of the pressure source is connected to a primary circuit via the balancing unit. The pressure source is also connected to both the receiving unit and the switching unit. One end of the switching unit is connected to the primary circuit, and the other end is connected to the receiving unit.

[0014] The balancing unit includes a housing, on which a first channel and a second channel are provided. A control mechanism is provided between the first channel and the second channel. The first channel is connected to the pressure source, and the second channel is connected to the primary circuit. The control mechanism is used to control the on / off connection between the first channel and the second channel to satisfy the overpressure protection of the pressure source to the primary circuit side, the automatic pressure replenishment of the primary circuit to the pressure source side, and the pressure maintenance function of the pressure source.

[0015] According to one embodiment of the present invention, the housing forms a receiving chamber between the first channel and the second channel, and the control mechanism is disposed in the receiving chamber;

[0016] The control mechanism includes a movable rod and a movable sleeve that are movably engaged. The movable rod is sleeved inside the movable sleeve and slides in cooperation with the movable sleeve along the axial direction of the movable sleeve. The movable sleeve is sleeved inside the accommodating cavity and slides in cooperation with the outer shell along the axial direction of the outer shell.

[0017] The moving sleeve and the moving rod are movably sealed to connect or close the first channel and the second channel.

[0018] According to one embodiment of the present invention, a check rod is provided at the bottom of the moving rod, and a first elastic element is sleeved on the outside of the check rod, with the bottom end of the moving sleeve abutting against the top end of the first elastic element;

[0019] A first placement gap is provided between the motion rod and the motion sleeve. A second elastic element is provided in the first placement gap. The second elastic element is sleeved on the outside of the motion rod and one end is fixedly connected to the motion rod. The other end of the second elastic element abuts against the motion sleeve.

[0020] The first elastic element and the second elastic element cooperate to drive the moving rod and the moving sleeve to move and seal.

[0021] According to one embodiment of the present invention, the top of the moving rod is provided with a mating protrusion, the lower end face of the mating protrusion is a first annular sealing surface, and the top of the moving sleeve is provided with a second annular sealing surface corresponding to the first annular sealing surface;

[0022] When the first circuit is operating normally, the moving sleeve is in a stationary state, and the second elastic element pulls the moving rod down to the first annular sealing surface and the second annular sealing surface to abut and seal.

[0023] When the first channel is overpressurized, the medium in the pressure source acts on the second annular sealing surface and drives the moving sleeve to compress the first elastic element and the second elastic element downward to separate the first annular sealing surface and the second annular sealing surface;

[0024] When the pressure of the pressure source decreases, the medium in the first circuit acts on the first annular sealing surface through the second channel and drives the moving rod to move upward to separate the first annular sealing surface and the second annular sealing surface.

[0025] According to one embodiment of the present invention, a round nut is provided at the bottom of the moving rod, the round nut is sleeved on the outside of the moving rod and threadedly connected to the moving rod, one end of the second elastic member abuts against the round nut, and the round nut is used to adjust the initial preload of the second elastic member.

[0026] According to one embodiment of the present invention, the middle part of the motion sleeve has a protrusion that cooperates with the motion rod;

[0027] The moving sleeve forms a first placement gap and a second placement gap between the moving rod and the opposite sides of the protrusion, respectively, and the second placement gap communicates with the second channel.

[0028] According to one embodiment of the present invention, a movable chamber is formed between the top of the moving sleeve and the mating protrusion, the first channel communicates with the movable chamber, and the second channel communicates with the movable chamber via the second placement gap.

[0029] According to one embodiment of the present invention, the inner cavity of the outer shell is further provided with a limiting sleeve, the limiting sleeve is sleeved on the outside of the moving sleeve, one end of the limiting sleeve extends to the top of the outer shell, and the top of the outer shell is further provided with an end cap, the end cap is covered by the limiting sleeve and connected to the outer shell;

[0030] The other end of the limiting sleeve extends toward the inner side of the receiving cavity and forms a check surface. The bottom of the moving sleeve is provided with a check step, and the top surface of the check step is located below the check surface. The check surface is used to limit the upward path of the moving sleeve.

[0031] According to one embodiment of the present invention, the limiting sleeve is provided with at least one flow groove along the outer circumference of the moving rod, one end of the flow groove extends to the top of the limiting sleeve and communicates with the first channel, and the other end communicates with the movable chamber.

[0032] According to one embodiment of the present invention, the number of the flow grooves is at least two, and the at least two flow grooves are evenly distributed around the outer circumference of the moving rod.

[0033] According to one embodiment of the present invention, the first channel is located at the top of the receiving chamber;

[0034] The second channel is opened on the side of the outer shell and passes through the limiting sleeve and the moving sleeve in sequence, communicating with the second placement gap.

[0035] According to one embodiment of the present invention, the end cap is provided with a flow hole along the axial direction of the outer shell, and the flow hole is connected to the flow groove to form the first channel.

[0036] According to one embodiment of the present invention, a base is provided at the bottom of the inner cavity of the outer shell, and a mounting hole is provided on the base, and one end of the check rod is threaded into the mounting hole;

[0037] The top of the check rod is provided with a guide groove, and one end of the moving rod is movably inserted into the guide groove.

[0038] According to one embodiment of the present invention, the receiving unit is a storage tank for storing the medium flowing out through the primary loop.

[0039] According to one embodiment of the present invention, a control unit is further provided on one side of the pressure source, the control unit being used to receive an opening signal and discharge the medium in the pressure source to the receiving unit.

[0040] The present invention also provides a one-loop safety control method, characterized in that it is implemented using the one-loop safety control system described above, the control method comprising:

[0041] Receive the start signal and open the control unit to depressurize the pressure source;

[0042] After the pressure source is depressurized to the point that the switching unit is opened, the medium in the primary circuit flows to the receiving unit through the two flow paths of the switching unit and the pressure source.

[0043] The positive and progressive effects of this invention are as follows:

[0044] The primary loop safety control system of this invention sets up a balancing unit between the pressure source and the primary loop, which automatically completes the overpressure protection, automatic pressure replenishment and pressure maintenance functions of the pressure source. It eliminates the need for separate temperature and pressure monitoring units, leakage monitoring units and other equipment, which simplifies the structural configuration of the primary loop side control system and meets the space layout requirements of small reactors. Attached Figure Description

[0045] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein:

[0046] Figure 1 This is a schematic diagram of a traditional one-loop safety control system.

[0047] Figure 2 This is a schematic diagram of the one-loop safety control system of the present invention;

[0048] Figure 3 This is a schematic diagram of a cross-section of the balancing unit of the present invention;

[0049] Figure 4 for Figure 3 A partial structural diagram of the balancing unit at one angle;

[0050] Figure 5 for Figure 3 A partial structural diagram of the balancing unit from another angle.

[0051] 1. Pressure source;

[0052] 2. Receiving unit;

[0053] 3. Switching unit;

[0054] 4. Balancing unit; 41. Outer shell; 411. Receiving chamber; 42. First channel; 43. Second channel; 44. Control mechanism; 441. Moving rod; 4411. Matching protrusion; 4412. First annular sealing surface; 4413. Round nut; 442. Moving sleeve; 4421. Second annular sealing surface; 4422. Protrusion; 4423. Second placement gap; 4424. Movable chamber; 4425. Check valve surface; 443. First placement gap; 444. Second elastic element; 445. Check valve rod; 451. Guide groove; 46. First elastic element; 47. Limiting sleeve; 471. Check valve step; 472. Flow groove; 48. End cap; 481. Flow hole; 49. Base; 491. Mounting hole;

[0055] 5. One circuit;

[0056] 6. Control unit. Detailed Implementation

[0057] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0059] Please refer to Figures 1 to 5 The present invention proposes a single-loop safety control system, including a pressure source 1, a receiving unit 2, a switching unit 3 and a balancing unit 4. One end of the pressure source 1 is connected to a single loop 5 through the balancing unit 4. The pressure source 1 is also connected to the receiving unit 2 and the switching unit 3 respectively. One end of the switching unit 3 is connected to the single loop 5 and the other end is connected to the receiving unit 2.

[0060] The balancing unit 4 includes a housing 41, on which a first channel 42 and a second channel 43 are provided. A control mechanism 44 is provided between the first channel 42 and the second channel 43. The first channel 42 is connected to the pressure source 1, and the second channel 43 is connected to the primary circuit 5. The control mechanism 44 is used to control the on / off connection between the first channel 42 and the second channel 43 to satisfy the overpressure protection of the pressure source 1 to the primary circuit 5 side, the automatic pressure replenishment from the primary circuit 5 to the pressure source 1 side, and the pressure maintenance function of the pressure source 1.

[0061] The pressure source 1 and the primary loop 5 include a first flow path and a second flow path. The first flow path is configured such that when the pressure source 1 is overpressurized, the pressure in the pressure source 1 flows to the primary loop 5 for depressurization. The second flow path is configured such that when the pressure source 1 needs to be pressurized, the primary loop 5 pressurizes the pressure source 1.

[0062] Reference Figure 1 In a traditional primary loop control system, when primary loop 5 is operating normally, switch unit 3 is in the closed state. However, when a rupture occurs in primary loop 5, control unit 6 receives the rupture signal and vents the pressure source 1. Once the pressure in pressure source 1 is released to the limit at which switch unit 3 can be opened, switch unit 3 opens, and the medium in primary loop 5 flows to receiving unit 2, thus realizing the discharge of medium after a failure in primary loop 5.

[0063] Because pressure source 1 is located in a high-temperature and high-pressure environment, overpressure may occur. To address the overpressure problem of pressure source 1, it is generally necessary to install overpressure discharge units, pressure replenishment units, temperature and pressure monitoring units, and leakage monitoring units outside pressure source 1 to identify the problem and control the pressure state of pressure source 1. These units can be actively or passively designed, but all require the consideration of corresponding support systems, such as power supply and gas supply. This approach would make the control system structure too complex and unsuitable for small modular reactor (SMR) designs. The high-temperature and high-pressure environment of pressure source 1 can be caused by heat transfer from the primary loop heat source or by thermal radiation; the specific cause is not limited here. Figure 1 The dashed line between the intermediate loop 5 and the pressure source 1 represents the heat transfer path.

[0064] Furthermore, a pressure replenishment mechanism is required for pressure source 1. Without this mechanism, leakage from pressure source 1 itself could cause switch unit 3 to open erroneously. However, the addition of a pressure replenishment mechanism would undoubtedly increase the complexity of pressure source 1's structure, making it unsuitable for the miniaturization design requirements of small modular reactors.

[0065] Based on this, this application sets up a balancing unit 4 between the pressure source 1 and the primary loop 5. The balancing unit 4 is used to provide overpressure protection, automatic pressure replenishment and pressure maintenance for the pressure source 1. As a result, the integration and simplification of the system are greatly improved. There is no need to set up separate temperature and pressure monitoring units, leakage monitoring units and other equipment. This simplifies the structural configuration of the control system on the primary loop 5 side and is conducive to meeting the space layout requirements of small reactors.

[0066] Specifically, a receiving chamber 411 is formed inside the outer casing 41 between the first channel 42 and the second channel 43, and the control mechanism 44 is disposed in the receiving chamber 411. It can be seen that the outer casing 41 is usually placed vertically, and the receiving chamber 411 is arranged along the axial direction of the outer casing 41 and extends from the top to the bottom of the outer casing 41.

[0067] Please refer to Figure 3 In one embodiment, the outer casing 41 has a receiving chamber 411 extending downward from its top along its axial direction, and the receiving chamber 411 is generally elongated cylindrical. Correspondingly, a first channel 42 may be provided at the top of the outer casing 41, and a second channel 43 may be provided at the side of the outer casing 41.

[0068] The control mechanism 44 in this application specifically includes a movable rod 441 and a movable sleeve 442. The movable rod 441 is sleeved in the movable sleeve 442 and slides in cooperation with the movable sleeve 442 along the axial direction of the movable sleeve 442. The movable sleeve 442 is sleeved in the accommodating chamber 411 and slides in cooperation with the outer shell 41 along the axial direction of the outer shell 41.

[0069] The moving sleeve 442 and the moving rod 441 are movably sealed to connect or close the first channel 42 and the second channel 43.

[0070] That is, this application uses the movable seal between the moving rod 441 and the moving sleeve 442 to connect or close the first channel 42 and the second channel 43 to achieve the functions of pressure source 1 overpressure protection, automatic pressure replenishment and pressure maintenance.

[0071] Please refer to the details. Figures 3 to 5 The bottom of the moving rod 441 is provided with a check rod 445, and a first elastic element 46 is sleeved on the outside of the check rod 445. The bottom end of the moving sleeve 442 abuts against the top end of the first elastic element 46. A first placement gap 443 is provided between the moving rod 441 and the moving sleeve 442. A second elastic element 444 is provided in the first placement gap 443. The second elastic element 444 is sleeved on the outside of the moving rod 441 and one end is fixedly connected to the moving rod 441. The other end of the second elastic element 444 abuts against the moving sleeve 442. The first elastic element 46 and the second elastic element 444 cooperate to drive the moving rod 441 and the moving sleeve 442 to move and seal.

[0072] The check rod 445 is used to support and limit the moving rod 441 so that the moving rod 441 can move upward along the axis of the moving sleeve 442 and limit its downward distance when the moving rod 441 moves downward.

[0073] In one embodiment, a base 49 is provided at the bottom of the inner cavity of the outer shell 41, and a mounting hole 491 is provided on the base 49. One end of the check rod 445 is threaded into the mounting hole 491. A guide groove 451 is provided at the top of the check rod 445, and one end of the moving rod 441 is movably inserted into the guide groove 451.

[0074] In some other embodiments, the check rod 445 can also be connected to the base 49 by welding, snap-fitting or other methods, which are not limited here.

[0075] The first elastic element 46 and the second elastic element 444 are used to provide a movable seal between the moving sleeve 442 and the moving rod 441.

[0076] Specifically, the top of the moving rod 441 is provided with a mating protrusion 4411, the lower end surface of the mating protrusion 4411 is a first annular sealing surface 4412, and the top of the moving sleeve 442 is provided with a second annular sealing surface 4421 corresponding to the first annular sealing surface 4412.

[0077] It can be seen that when the primary circuit 5 is running normally, the moving sleeve 442 is in a relatively static state. One end of the second elastic element 444 abuts against the moving sleeve 442, and the other end pulls down the moving rod 441, driving the first annular sealing surface 4412 of the moving rod 441 to fit tightly against the second annular sealing surface 4421 of the moving sleeve 442, so as to disconnect the first channel 42 and the second channel 43.

[0078] That is, the first elastic element 46 provides upward elastic support to the moving sleeve 442, while the second elastic element 444 provides downward pulling force to the moving rod 441. As a result, the first annular sealing surface 4412 and the second annular sealing surface 4421 can fit tightly together, thereby disconnecting the first channel 42 and the second channel 43.

[0079] When pressure source 1 experiences overpressure, the medium within pressure source 1 acts on the second annular sealing surface 4421 and drives the moving sleeve 442 downward to overcome the elastic force of the first elastic element 46 and the second elastic element 444 until the first annular sealing surface 4412 and the second annular sealing surface 4421 are separated. At this time, the first channel 42 and the second channel 43 are connected, and the medium in the first channel 42 flows to the primary circuit 5 through the second channel 43 for pressure reduction. As the pressure of pressure source 1 decreases, the elastic force of the first elastic element 46 and the second elastic element 444 gradually recovers and eventually returns to the sealing state of the first annular sealing surface 4412 and the second annular sealing surface 4421, thus satisfying the overpressure protection function of pressure source 1.

[0080] When the pressure of pressure source 1 drops, the medium in primary circuit 5 acts on the first annular sealing surface 4412 through the second channel 43 and drives the moving rod 441 to move upward to separate the first annular sealing surface 4412 and the second annular sealing surface 4421.

[0081] That is, when pressure source 1 leaks and causes a pressure drop, the moving rod 441 compresses the second elastic element 444 and moves upward, separating the first annular sealing surface 4412 and the second annular sealing surface 4421. The medium in the primary circuit 5 flows to pressure source 1 through the first channel 42 for pressure replenishment. As the pressure in pressure source 1 gradually rises to the rated pressure, the second elastic element 444 also gradually pulls the moving rod 441 downward until the first annular sealing surface 4412 and the second annular sealing surface 4421 come into contact and return to the initial sealing state, thereby satisfying the automatic pressure replenishment function of pressure source 1.

[0082] In one embodiment, a round nut 4413 is provided at the bottom of the moving rod 441. The round nut 4413 is sleeved on the outside of the moving rod 441 and threadedly connected to the moving rod 441. One end of the second elastic member 444 abuts against the round nut 4413. The round nut 4413 is used to adjust the initial preload of the second elastic member 444.

[0083] That is, the top end of the second elastic element 444 abuts against the moving sleeve 442, while the bottom end abuts against the round nut 4413. Under normal operating conditions of the primary circuit 5, the medium in the second channel 43 cannot overcome the pre-tightening force of the first elastic element 46. The moving sleeve 442 is relatively stationary. The top end of the second elastic element 444 is supported by the moving sleeve 442, and the bottom end applies elastic force to the round nut 4413 and pulls the moving rod 441 downward, so that the first annular sealing surface 4412 and the second annular sealing surface 4421 seal against each other.

[0084] Please continue to refer to Figure 3 The middle part of the moving sleeve 442 has a protrusion 4422 that cooperates with the moving rod 441; the moving sleeve 442 forms a first placement gap 443 and a second placement gap 4423 between the moving rod 441 on the opposite sides of the protrusion 4422, and the second placement gap 4423 is connected to the second channel 43.

[0085] Specifically, the moving rod 441 passes through the protrusion 4422. Because the protrusion 4422 protrudes, the inner diameter of the moving sleeve 442 at the position of the protrusion 4422 corresponds to the moving rod 441. The inner diameter of the moving sleeve 442 on both sides of the protrusion 4422 is larger than the diameter of the moving rod 441, thus forming a first placement gap 443 and a second placement gap 4423. The first placement gap 443 is used to place the second elastic member 444, and the second placement gap 4423 is used for flow guidance, so that the medium in the second channel 43 flows through the second placement gap 4423 to the side close to the mating protrusion 4411.

[0086] Please refer to Figure 4 and Figure 5 An active chamber 4424 is formed between the top of the moving sleeve 442 and the mating protrusion 4411. The first channel 42 communicates with the active chamber 4424, and the second channel 43 communicates with the active chamber 4424 through the second placement gap 4423.

[0087] That is, there is a second placement gap 4423 and a movable chamber 4424 between the first channel 42 and the second channel 43. When the first annular sealing surface 4412 and the second annular sealing surface 4421 are separated, the first channel 42 and the second channel 43 are connected; and when the first annular sealing surface 4412 and the second annular sealing surface 4421 are in contact, the first channel 42 and the second channel 43 are disconnected.

[0088] Optionally, the inner cavity of the outer shell 41 is also provided with a limiting sleeve 47, which is fitted on the outside of the moving sleeve 442. One end of the limiting sleeve 47 extends to the top of the outer shell 41. The top of the outer shell 41 is also provided with an end cap 48, which covers the limiting sleeve 47 and is connected to the outer shell 41. The other end of the limiting sleeve 47 extends toward the inner side of the receiving chamber 411 and forms a check surface 4425. The bottom of the moving sleeve 442 is provided with a check step 471, the top surface of which is located below the check surface 4425. The check surface 4425 is used to limit the upward path of the moving sleeve 442.

[0089] The end cap 48 and the limiting sleeve 47 can be connected by a threaded connector, or by snap-fit, welding, or other methods, which are not limited here. The limiting sleeve 47 is set to limit the movement sleeve 442 and prevent the movement sleeve 442 from detaching from the outer shell 41.

[0090] In the initial state, the first elastic element 46 can be in a compressed state or a free, unforced state. When the first elastic element 46 is in a compressed state, the limiting sleeve 47 can limit the moving sleeve 442 at the check step 471, so that the moving sleeve 442 elastically presses against the check surface 4425.

[0091] When the first elastic element 46 is in a free and unforced state, the check step 471 can limit the upward movement of the moving sleeve 442.

[0092] In practical applications, the first elastic element 46 can be selected from springs with different elastic moduli as needed, and no limitation is made here.

[0093] In one embodiment, the limiting sleeve 47 is provided with at least one flow groove 472 along the outer periphery of the moving rod 441. One end of the flow groove 472 extends to the top of the limiting sleeve 47 and communicates with the first channel 42, and the other end communicates with the movable chamber 4424.

[0094] The top of the limiting sleeve 47 limits the up and down sliding of the moving rod 441 to prevent the moving rod 441 from deflecting when it slides along the axial direction of the outer shell 41. In order to connect the first channel 42 and the second channel 43, a flow groove 472 is provided on the limiting sleeve 47 around the outer circumference of the moving rod 441. The flow groove 472 is used to open up the first channel 42 and the movable chamber 4424.

[0095] Specifically, there are at least two flow channels 472, and the at least two flow channels 472 are evenly distributed around the outer periphery of the moving rod 441.

[0096] At least two flow channels 472 are evenly distributed around the outer periphery of the moving rod 441, thereby improving the flow stability of the medium from the first channel 42 to the moving chamber 4424.

[0097] Please refer to Figure 4 and Figure 5 In one embodiment, the first channel 42 is located at the top of the accommodating chamber 411; the second channel 43 is opened on the side of the outer shell 41 and passes through the limiting sleeve 47 and the moving sleeve 442 in sequence, communicating with the second placement gap 4423.

[0098] The placement of the first channel 42 and the second channel 43 is merely an example and is not limited here.

[0099] Specifically, the end cap 48 has a flow hole 481 along the axial direction of the outer shell 41. The flow hole 481 is connected to the flow groove 472 and forms the first channel 42.

[0100] Pressure source 1 is connected to the first channel 42 through a pipeline, and primary circuit 5 is connected to the second pipeline through a pipeline. The control mechanism 44 set between the first channel 42 and the second channel 43 is used to control the opening and closing of the first channel 42 and the second channel 43, thereby satisfying the functions of pressure source 1 overpressure protection, automatic pressure replenishment and pressure maintenance.

[0101] In one embodiment, the receiving unit 2 is a storage tank used to store the medium flowing out through the primary loop 5.

[0102] Furthermore, a control unit 6 is also provided on one side of the pressure source 1. The control unit 6 is used to receive the opening signal and discharge the medium in the pressure source 1 to the receiving unit 2.

[0103] The control unit 6 can also be a solenoid valve, control switch, or other similar structure, and is not limited here. The receiving unit 2 is used to store the medium flowing out of the primary loop 5, or to replenish the stored medium into the primary loop 5.

[0104] The assembly process of one embodiment of the balancing unit 4 is described below:

[0105] The first step is to connect the base 49 and the check rod 445 with threads, and then install the base 49 and the check rod 445 into the receiving chamber 411 of the housing 41. During the installation process, it is necessary to ensure that the check rod 445 and the base 49 are inserted along the axial direction of the housing 41 to avoid scratching the inner wall of the housing 41.

[0106] The second step is to fit the first elastic element 46 onto the outside of the check rod 445.

[0107] The third step is to insert the moving rod 441 into the moving sleeve 442, and make the first annular sealing surface 4412 fit with the second annular sealing surface 4421. Then, install the second elastic element 444 into the first placement gap 443, and then install the round nut 4413 and tighten the round nut 4413 to the target preload set by the second elastic element 444, thus completing the assembly of the moving sleeve 442 and the moving rod 441.

[0108] The fourth step is to place the limiting sleeve 47 outside the movement sleeve 442.

[0109] Fifth step, lay the outer shell 41 horizontally, and then install the assembled limiting sleeve 47, moving sleeve 442 and moving rod 441 into the outer shell 41. The bottom end of the moving sleeve 442 elastically abuts against the first elastic member 46. Then, the end cover 48 is installed with the outer shell 41 using a threaded connector, and finally the assembly of the balance unit 4 is completed.

[0110] The working principle of balancing unit 4 is explained as follows:

[0111] During normal operation of the primary circuit 5, the moving sleeve 442 is stationary. The top of the second elastic element 444 is supported by the moving sleeve 442, and its elasticity drives the bottom end to act on the round nut 4413, thereby pulling down the moving rod 441, so that the first annular sealing surface 4412 of the moving rod 441 abuts against the second annular sealing surface 4421 of the moving sleeve 442. At this time, the medium in the second channel 43 cannot push the second elastic element 444 open, thereby closing the first channel 42 and the second channel 43.

[0112] When there is overpressure on the pressure source 1 side, the pressure on the first channel 42 side exceeds the preload of the first elastic element 46 and the second elastic element 444. As a result, the medium in the first channel 42 flows through the flow groove 472 into the movable chamber 4424 and acts on the second annular sealing surface 4421 of the moving sleeve 442, driving the moving sleeve 442 downwards. At this time, the moving rod 441 remains stationary due to the support of the check rod 445. Then, the first annular sealing surface 4412 and the second annular sealing surface 4421 separate, and the medium in the first channel 42 flows into the second channel 43, and finally into the primary circuit 5. During the depressurization process of the first channel 42, the elasticity of the first elastic element 46 and the second elastic element 444 gradually recovers. Finally, after the pressure in the pressure source 1 drops to the rated value, the first elastic element 46 and the second elastic element 444 also recover to their initial preload, and the first annular sealing surface 4412 and the second annular sealing surface 4421 reseal.

[0113] For example, when the pressure on the first elastic element 46 and the second elastic element 444 on the first channel 42 side reaches 14MPa, the first annular sealing surface 4412 separates from the second annular sealing surface 4421.

[0114] When the pressure on the pressure source 1 side exceeds 14MPa, it is in an overpressure state. The medium on the first channel 42 side will flow to the primary circuit 5 side to relieve pressure. When the pressure is relieved to below 14MPa, the first annular sealing surface 4412 and the second annular sealing surface 4421 will restore the sealing state under the elastic force of the first elastic member 46 and the second elastic member 444.

[0115] When the pressure of pressure source 1 drops, due to the pressure difference, the medium pressure in the second channel 43 overcomes the elastic force of the second elastic element 444, but does not overcome the elastic force of the first elastic element 46. As a result, the moving sleeve 442 is stationary. The medium in the second channel 43 flows into the second placement gap 4423 and acts on the first annular sealing surface 4412, driving the moving rod 441 to move upward and separate the first annular sealing surface 4412 and the second annular sealing surface 4421. Then the medium in the primary circuit 5 can replenish the pressure of pressure source 1. As the pressure of pressure source 1 gradually rises to the rated pressure, the elastic force of the second elastic element 444 also gradually recovers. Finally, the first annular sealing surface 4412 and the second annular sealing surface 4421 reseal each other.

[0116] It can be seen that the medium on the second channel 43 side only needs to overcome the second elastic element 444 to flow to the pressure source 1. Specifically, it can be set that when the pressure difference is 2MPa, the medium on the first loop 5 side can overcome the elastic force of the second elastic element 444, thereby automatically replenishing the pressure to the pressure source 1 side through the first loop 5.

[0117] In non-breakage accident conditions, the pressure of primary circuit 5 may drop to a lower level. At this time, it is necessary to keep switch unit 3 closed and the pressure of pressure source 1 needs to be kept above a certain level.

[0118] The medium pressure on the pressure source 1 side of this application cannot overcome the elastic force of the first elastic element 46 and the second elastic element 444, so the first channel 42 and the second channel 43 remain closed. At this time, the pressure of the pressure source 1 is not affected by the pressure drop of the primary circuit 5 and can still be stabilized within the normal operating pressure range. This can also prevent the switch unit 3 connected to the primary circuit 5 from being accidentally opened, causing a break in the primary circuit 5.

[0119] In the event of a rupture in primary circuit 5, control unit 6 receives an opening signal and controls pressure source 1 to be open to release pressure. When the pressure in pressure source 1 drops to the opening pressure of switch unit 3, switch unit 3 opens, allowing the medium in primary circuit 5 to be discharged to receiving unit 2 through switch unit 3. At this time, the pressure in pressure source 1 decreases, and the medium in second channel 43 acts on the first annular sealing surface 4412 to flow into second channel 43, and then through control unit 6 to receiving unit 2. This forms two pathways to discharge the medium in primary circuit 5, meeting the flow meter discharge time requirements after an accident.

[0120] This application also meets the water replenishment requirement from receiving unit 2 to primary loop 5. Specifically, after receiving the water replenishment requirement, the pressure source 1 is depressurized, the switch unit 3 is opened, and the water in receiving unit 2 can be replenished to primary loop 5 through the switch unit 3.

[0121] In summary, the balancing unit 4 provided in this application can meet the overpressure protection, pressure replenishment and pressure maintenance functions of the pressure source 1 of the primary loop 5; moreover, the balancing unit 4 adopts a mechanical active seal method, which can work in high temperature and high pressure environment, and the logic is simple. It can meet the system operation balance without adding other control system designs, thereby reducing the construction and maintenance costs of nuclear power plants.

[0122] This invention also proposes a one-loop safety control method, implemented using the above-described one-loop safety control system. The control method includes:

[0123] Receive the start signal and open the control unit to depressurize the pressure source;

[0124] After the pressure source is depressurized to the point where the switching unit is opened, the medium in the primary circuit flows to the receiving unit through two flow paths: the switching unit and the pressure source.

[0125] This application meets the requirement of discharging primary circuit medium through two flow paths under primary circuit breach conditions, and satisfies the requirements for discharge flow rate and discharge time after an accident.

[0126] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation", "connection", "joining", and "fixing" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can also refer to mechanical connections. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0127] This application uses specific terms to describe embodiments of the application. Terms such as "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0128] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A single-loop safety control system, characterized in that, include: The system comprises a pressure source, a receiving unit, a switching unit, and a balancing unit. One end of the pressure source is connected to a primary circuit via the balancing unit. The pressure source is also connected to both the receiving unit and the switching unit. One end of the switching unit is connected to the primary circuit, and the other end is connected to the receiving unit. The balancing unit includes a housing, on which a first channel and a second channel are provided. A control mechanism is provided between the first channel and the second channel. The first channel is connected to the pressure source, and the second channel is connected to the primary circuit. The control mechanism is used to control the on / off connection between the first channel and the second channel to satisfy the overpressure protection of the pressure source to the primary circuit side, the automatic pressure replenishment of the primary circuit to the pressure source side, and the pressure maintenance function of the pressure source.

2. The single-loop safety control system according to claim 1, characterized in that, The outer casing forms a receiving chamber between the first channel and the second channel, and the control mechanism is disposed in the receiving chamber; The control mechanism includes a movable rod and a movable sleeve that are movably engaged. The movable rod is sleeved inside the movable sleeve and slides in cooperation with the movable sleeve along the axial direction of the movable sleeve. The movable sleeve is sleeved inside the accommodating cavity and slides in cooperation with the outer shell along the axial direction of the outer shell. The moving sleeve and the moving rod are movably sealed to connect or close the first channel and the second channel.

3. The single-loop safety control system according to claim 2, characterized in that, The bottom of the moving rod is provided with a check rod, and a first elastic element is sleeved on the outside of the check rod. The bottom end of the moving sleeve abuts against the top end of the first elastic element. A first placement gap is provided between the motion rod and the motion sleeve. A second elastic element is provided in the first placement gap. The second elastic element is sleeved on the outside of the motion rod and one end is fixedly connected to the motion rod. The other end of the second elastic element abuts against the motion sleeve. The first elastic element and the second elastic element cooperate to drive the moving rod and the moving sleeve to move and seal.

4. The single-loop safety control system according to claim 3, characterized in that, The top of the moving rod is provided with a mating protrusion, the lower end face of which is a first annular sealing surface, and the top of the moving sleeve is provided with a second annular sealing surface corresponding to the first annular sealing surface. When the first circuit is operating normally, the moving sleeve is in a stationary state, and the second elastic element pulls the moving rod down to the first annular sealing surface and the second annular sealing surface to abut and seal. When the first channel is overpressurized, the medium in the pressure source acts on the second annular sealing surface and drives the moving sleeve to compress the first elastic element and the second elastic element downward to separate the first annular sealing surface and the second annular sealing surface; When the pressure of the pressure source decreases, the medium in the first circuit acts on the first annular sealing surface through the second channel and drives the moving rod to move upward to separate the first annular sealing surface and the second annular sealing surface.

5. The single-loop safety control system according to claim 3, characterized in that, The bottom of the moving rod is provided with a round nut, which is sleeved on the outside of the moving rod and threadedly connected to the moving rod. One end of the second elastic element abuts against the round nut, and the round nut is used to adjust the initial preload of the second elastic element.

6. The single-loop safety control system according to claim 3, characterized in that, The middle part of the motion sleeve has a protrusion that cooperates with the motion rod; The moving sleeve forms a first placement gap and a second placement gap between the moving rod and the opposite sides of the protrusion, respectively, and the second placement gap communicates with the second channel.

7. The single-loop safety control system according to claim 6, characterized in that, A movable chamber is formed between the top of the movement sleeve and the mating protrusion. The first channel communicates with the movable chamber, and the second channel communicates with the movable chamber through the second placement gap.

8. The single-loop safety control system according to claim 7, characterized in that, The inner cavity of the outer shell is also provided with a limiting sleeve, which is sleeved on the outside of the moving sleeve. One end of the limiting sleeve extends to the top of the outer shell. The top of the outer shell is also provided with an end cap, which covers the limiting sleeve and is connected to the outer shell. The other end of the limiting sleeve extends toward the inner side of the receiving cavity and forms a check surface. The bottom of the moving sleeve is provided with a check step, and the top surface of the check step is located below the check surface. The check surface is used to limit the upward path of the moving sleeve.

9. The single-loop safety control system according to claim 8, characterized in that, The limiting sleeve has at least one flow groove circumferentially formed along the outer periphery of the moving rod. One end of the flow groove extends to the top of the limiting sleeve and communicates with the first channel, while the other end communicates with the movable chamber.

10. The single-loop safety control system according to claim 9, characterized in that, The number of flow channels is at least two, and the at least two flow channels are evenly distributed around the outer circumference of the moving rod.

11. The single-loop safety control system according to claim 8, characterized in that, The first channel is located at the top of the accommodating chamber; The second channel is opened on the side of the outer shell and passes through the limiting sleeve and the moving sleeve in sequence, communicating with the second placement gap.

12. The single-loop safety control system according to claim 8, characterized in that, The end cap has a flow hole along the axial direction of the outer shell, and the flow hole is connected to the flow groove to form the first channel.

13. The single-loop safety control system according to claim 3, characterized in that, The bottom of the inner cavity of the outer shell is provided with a base, and the base is provided with a mounting hole. One end of the check rod is threaded into the mounting hole. The top of the check rod is provided with a guide groove, and one end of the moving rod is movably inserted into the guide groove.

14. The single-loop safety control system according to any one of claims 1-13, characterized in that, The receiving unit is a storage tank used to store the medium flowing out through the primary loop.

15. The single-loop safety control system according to any one of claims 1-13, characterized in that, A control unit is also provided on one side of the pressure source. The control unit is used to receive an opening signal and discharge the medium in the pressure source to the receiving unit.

16. A single-loop safety control method, characterized in that, The control method is implemented using a one-loop safety control system as described in any one of claims 1-15, wherein the control method includes: Receive the start signal and open the control unit to depressurize the pressure source; After the pressure source is depressurized to the point that the switching unit is opened, the medium in the primary circuit flows to the receiving unit through the two flow paths of the switching unit and the pressure source.

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