Primary loop safety control system and control method

Abstract

The invention provides a primary loop safety control system and control method.The control system comprises a pressure source, a receiving unit, a switch unit and a balance unit, one end of the pressure source is connected with a primary loop through the balance unit, the pressure source is further connected with the receiving unit and the switch unit, and one end of the switch unit is connected with the primary loop; the other end is connected to the receiving unit; the balance unit comprises a shell, a first channel and a second channel are arranged on the shell, a control mechanism is arranged between the first channel and the second channel, the first channel is connected with a pressure source, the second channel is connected with a loop, and the control mechanism is used for controlling connection and disconnection between the first channel and the second channel. Therefore, the functions of overpressure protection from the pressure source to the primary loop side, automatic pressure supplement from the primary loop to the pressure source side and pressure maintaining of the pressure source are achieved. According to the primary loop safety control system, the structural configuration of the primary loop side control system is simplified, and the spatial arrangement requirement of a small reactor is met.

Description

Technical Field

[0001] The present invention relates to the technical field of primary loop safety control, and particularly relates to a primary loop safety control system and a control method. Background Art

[0002] With the trend of simplification and miniaturization in nuclear power plant design, the equipment connected to the primary loop not only needs to perform the function of pressure boundary isolation, but also needs to perform the function of accident mitigation, including that related equipment can perform effective actions after an accident to meet the requirements of primary loop pressure reduction and water replenishment.

[0003] In order for the equipment connected to the primary loop to perform related functions, it may be necessary to configure a power source to meet the requirements of triggering equipment actions after an accident. The power source can adopt different methods such as electric, pneumatic, and hydraulic. For small nuclear power plants, the space inside the containment is limited, and the power source design needs to be simplified as much as possible to meet the requirements of layout design.

[0004] Among them, the electric method requires the installation of safety-class cables inside the containment. In addition to the large size of the electric device being unfavorable for layout, it also brings the problem of new safety-class cable penetrations. The pneumatic method not only has a larger size of the driving device, but also has the reliability problem of the supporting gas source system.

[0005] Therefore, for small reactors, designers generally prefer to use a hydraulic source for driving.

[0006] However, for the hydraulic source, whether it is a compact integrated design or a split design, two problems need to be considered. One is the problem of pressure reduction and pressure compensation caused by pressure source leakage. Although the traditional pipe connection design and active containment water replenishment method can utilize existing pumps and water sources, it is necessary to upgrade the active equipment to the safety level, which has certain deficiencies in terms of economy and space occupation. Moreover, such a system design is complex, occupies a large space, is not conducive to miniaturization and the research and development of new reactors, and lacks technological advancement.

[0007] Another problem is that since the equipment that operates after an accident is connected to the primary loop, the pressure source that maintains the equipment balance has a small volume due to the requirement of miniaturization. Affected by the high temperature of the primary loop, it will quickly transfer the heat of the primary loop to the pressure source, resulting in a rapid increase in the temperature of the pressure source. During the transient change process of the system, the pressure source is prone to overpressure problems. Once overpressure occurs, it will have a serious impact on the equipment and even cause equipment failure.

[0008] In the traditional method, an overpressure pipeline can be set up or a safety relief valve can be directly configured on the pressure chamber to discharge the fluid into the waste liquid system or the containment. Setting up the overpressure pipeline and the safety relief valve not only involves complex configuration, but also due to the limited space in the chamber, it may cause the chamber to lose pressure instantaneously during the discharge process and the chamber pressure cannot be quickly restored, resulting in unstable operation of the system or even causing misoperation of the equipment, so that abnormal transient conditions cannot be well alleviated and the accident condition of a primary loop break is upgraded.

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

[0010] The technical problem to be solved by the present invention is to overcome the defects that the traditional primary loop control system cannot meet the overpressure protection, automatic pressure replenishment and pressure holding functions of the pressure source, and to provide a primary loop safety control system and a control method.

[0011] The present invention solves the above technical problems through the following technical solutions:

[0012] The present invention provides a primary loop safety control system, which is characterized by including:

[0013] A pressure source, a receiving unit, a switching unit and a balancing unit. One end of the pressure source is connected to the primary loop through the balancing unit. The pressure source is also respectively connected to the receiving unit and the switching unit. One end of the switching unit is connected to the primary loop and the other end is connected to the receiving unit; wherein,

[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 loop. The control mechanism is used to control the on-off between the first channel and the second channel to meet the overpressure protection from the pressure source to the primary loop side, the automatic pressure replenishment from the primary loop to the pressure source side and the pressure holding function of the pressure source.

[0015] According to an embodiment of the present invention, a accommodation chamber is formed between the first channel and the second channel inside the housing, and the control mechanism is arranged in the accommodation chamber;

[0016] The control mechanism includes a moving rod and a moving sleeve that are movably matched. The moving rod is sleeved in the moving sleeve and slidably matched with the moving sleeve along the axial direction of the moving sleeve. The moving sleeve is sleeved in the accommodation chamber and slidably matched with the housing along the axial direction of the housing;

[0017] The movement sleeve and the movement rod are movably sealed for communicating or closing the first channel and the second channel.

[0018] According to an embodiment of the present invention, a check rod is provided at the bottom of the movement rod, a first elastic member is sleeved outside the check rod, and the top end of the first elastic member abuts against the bottom end of the movement sleeve;

[0019] A first placement gap is provided between the movement rod and the movement sleeve, a second elastic member is provided in the first placement gap, the second elastic member is sleeved outside the movement rod and one end thereof is fixedly connected to the movement rod, and the other end of the second elastic member abuts against the movement sleeve;

[0020] The first elastic member and the second elastic member cooperate to drive the movement rod and the movement sleeve to be movably sealed.

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

[0022] When the primary loop operates normally, the movement sleeve is in a stationary state, and the second elastic member pulls the movement rod downward until the first annular sealing surface abuts against and seals the second annular sealing surface;

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

[0024] When the pressure of the pressure source drops, the medium in the primary loop acts on the first annular sealing surface through the second channel and drives the movement rod upward to separate the first annular sealing surface and the second annular sealing surface.

[0025] According to an embodiment of the present invention, a round nut is provided at the bottom of the movement rod, the round nut is sleeved outside the movement rod and is threadedly connected to the movement rod, one end of the second elastic member abuts against the round nut, and the round nut is used to adjust the initial pre-tightening force of the second elastic member.

[0026] According to an embodiment of the present invention, the middle part of the movement sleeve has a convex part that cooperates with the movement rod;

[0027] The first placement gap and the second placement gap are respectively formed between the movement sleeve and the movement rod on opposite sides of the convex part, and the second placement gap communicates with the second channel.

[0028] According to an embodiment of the present invention, an activity chamber is formed between the top of the motion sleeve and the mating protrusion. The first channel communicates with the activity chamber, and the second channel communicates with the activity chamber through the second placement gap.

[0029] According to an embodiment of the present invention, a limit sleeve is further provided in the inner cavity of the outer shell. The limit sleeve is sleeved outside the motion sleeve. One end of the limit sleeve extends to the top of the outer shell. An end cover is further provided on the top of the outer shell. The end cover covers the limit sleeve and is connected to the outer shell.

[0030] The other end of the limit sleeve extends towards the inner side of the accommodating cavity and forms a check surface. A check step is provided at the bottom of the motion sleeve. 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 motion sleeve.

[0031] According to an embodiment of the present invention, at least one flow groove is circumferentially formed on the outer circumference of the limit sleeve along the motion rod. One end of the flow groove extends to the top end of the limit sleeve and communicates with the first channel, and the other end communicates with the activity chamber.

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

[0033] According to an embodiment of the present invention, the first channel is located at the top of the accommodating cavity.

[0034] The second channel is opened on the side of the outer shell and sequentially penetrates through the limit sleeve and the motion sleeve to communicate with the second placement gap.

[0035] According to an embodiment of the present invention, a flow hole is axially formed on the end cover along the outer shell. The flow hole communicates with the flow groove and forms the first channel.

[0036] According to an embodiment of the present invention, a base is provided at the bottom of the inner cavity of the outer shell. An installation hole is formed on the base. One end of the check rod is threadedly installed in the installation hole.

[0037] A guide groove is formed at the top of the check rod. One end of the motion rod is movably inserted into the guide groove.

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

[0039] According to an embodiment of the present invention, a control unit is further 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.

[0040] The present invention also provides a primary loop safety control method, characterized in that it is implemented by using the primary loop safety control system as described above. The control method includes:

[0041] Receiving an opening signal and opening the control unit to relieve the pressure of the pressure source;

[0042] After the pressure of the pressure source is relieved until the switch unit is opened, the medium in the primary loop flows to the receiving unit through two flow paths, namely the switch unit and the pressure source.

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

[0044] In the primary loop safety control system of the present invention, a balancing unit is provided between the pressure source and the primary loop, which automatically completes the functions of overpressure protection, automatic pressure compensation and pressure maintenance of the pressure source. There is no need to separately set up equipment such as temperature and pressure monitoring units and leakage monitoring units, which simplifies the structural configuration of the control system on the primary loop side and meets the space layout requirements of small reactors. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The above and other features, properties and advantages of the present invention will become more obvious through the following description with reference to the drawings and embodiments, where:

[0046] Figure 1 is a schematic diagram of a primary loop safety control system in the traditional way;

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

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

[0049] Figure 4 is Figure 3 a partial structural diagram of the balancing unit of

[0050] Figure 5 is Figure 3 a partial structural diagram of the balancing unit of

[0051] 1. Pressure source;

[0052] 2. Receiving unit;

[0053] 3. Switch unit;

[0054] 4. Balance unit; 41. Housing; 411. Accommodation chamber; 42. First channel; 43. Second channel; 44. Control mechanism; 441. Moving rod; 4411. Fitting protrusion; 4412. First annular sealing surface; 4413. Round nut; 442. Moving sleeve; 4421. Second annular sealing surface; 4422. Protrusion; 4423. Second placement gap; 4424. Activity chamber; 4425. Check surface; 443. First placement gap; 444. Second elastic member; 445. Check rod; 451. Guide groove; 46. First elastic member; 47. Limit sleeve; 471. Check step; 472. Flow channel; 48. End cover; 481. Flow hole; 49. Base; 491. Mounting hole;

[0055] 5. Primary loop;

[0056] 6. Control unit. Specific embodiments

[0057] The present invention will be further described below in conjunction with specific embodiments and the accompanying drawings. More details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention is obviously capable of being implemented in many other ways different from this description. Those skilled in the art can make similar generalizations and deductions according to the actual application situation without departing from the connotation of the present invention. Therefore, the protection scope 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 those of ordinary skill in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion.

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

[0060] Among them, the balance unit 4 includes a housing 41. A first channel 42 and a second channel 43 are provided on the housing 41. 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 loop 5. The control mechanism 44 is used to control the on-off between the first channel 42 and the second channel 43 to meet the overpressure protection from the pressure source 1 to the primary loop 5 side, the automatic pressure compensation from the primary loop 5 to the pressure source 1 side, and the pressure holding function of the pressure source 1.

[0061] Among them, between the pressure source 1 and the primary loop 5, there are a first flow path and a second flow path. The first flow path is configured such that when the pressure source 1 is overpressured, the pressure inside the pressure source 1 flows into the primary loop 5 for pressure relief; the second flow path is configured such that when the pressure source 1 needs pressure compensation, the primary loop 5 compensates the pressure to the pressure source 1 side.

[0062] Referring to Figure 1 , in the traditional primary loop control system, when the primary loop 5 is operating normally, the switch unit 3 is in the closed state. When a break occurs in the primary loop 5, the control unit 6 receives the break signal and evacuates the pressure of the pressure source 1. After the pressure of the pressure source 1 is discharged to the limit value at which the switch unit 3 can be opened, the switch unit 3 opens, and the medium of the primary loop 5 flows to the receiving unit 2 to achieve the medium discharge after the accident of the primary loop 5.

[0063] Moreover, since the pressure source 1 is in a high-temperature and high-pressure environment, overpressure phenomena may occur. If the overpressure problem of the pressure source 1 needs to be solved, generally, an overpressure discharge unit, a pressure compensation unit, a temperature and pressure monitoring unit, a leakage monitoring unit, etc. are set outside the pressure source 1 to identify the problem and control the pressure state of the pressure source 1. The relevant units can be active designs or passive designs, but corresponding support systems such as power supply and gas supply need to be considered. This method will make the control system structure too complex to meet the small reactor design requirements. Among them, the high-temperature and high-pressure environment where the pressure source 1 is located can be caused by heat transfer from the primary loop heat source or heat radiation, and the specific reason is not limited here. Figure 1 The dotted line between the primary loop 5 and the pressure source 1 in

[0064] Moreover, a pressure compensation mechanism also needs to be set on the pressure source 1. If the pressure compensation mechanism is not set, the self-leakage of the pressure source 1 may cause the switch unit 3 to open by mistake. And the method of setting the pressure compensation mechanism will undoubtedly also increase the complexity of the structure of the pressure source 1 and cannot meet the design requirements of miniaturization of small reactors.

[0065] Based on this, a balance unit 4 is provided between the pressure source 1 and the primary loop 5 in this application. The balance unit 4 is used for overpressure protection, automatic pressure supplementation, and pressure maintenance of the pressure source 1. As a result, the integration and simplification degree of the system are greatly improved, and there is no need to separately set up devices such as temperature and pressure monitoring units and leakage monitoring units, which simplifies the structural configuration of the control system on the primary loop 5 side and is conducive to meeting the spatial layout requirements of small reactors.

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

[0067] Please refer to Figure 3 , in one embodiment, the housing 41 is provided with a receiving chamber 411 axially downward from the top. The receiving chamber 411 is integrally in a long cylindrical shape. Correspondingly, the first channel 42 can be arranged at the top of the housing 41, and the second channel 43 is arranged at the side of the housing 41.

[0068] The control mechanism 44 in this application specifically includes a moving rod 441 and a moving sleeve 442 that are movably matched. The moving rod 441 is sleeved inside the moving sleeve 442 and is slidably matched with the moving sleeve 442 along the axis of the moving sleeve 442. The moving sleeve 442 is sleeved inside the receiving chamber 411 and is slidably matched with the housing 41 along the axis of the housing 41.

[0069] Among them, the moving sleeve 442 and the moving rod 441 are movably sealed to be used for connecting or closing the first channel 42 and the second channel 43.

[0070] That is to say, in this application, the first channel 42 and the second channel 43 are connected or closed through the movable seal between the moving rod 441 and the moving sleeve 442 to realize the functions of overpressure protection, automatic pressure supplementation, and pressure maintenance of the pressure source 1.

[0071] Specifically, please refer to Figures 3 to 5 , a check rod 445 is provided at the bottom of the moving rod 441. A first elastic member 46 is sleeved outside the check rod 445. The bottom end of the moving sleeve 442 abuts against the top end of the first elastic member 46. A first placement gap 443 is provided between the moving rod 441 and the moving sleeve 442. A second elastic member 444 is provided in the first placement gap 443. The second elastic member 444 is sleeved outside the moving rod 441 and one end is fixedly connected to the moving rod 441, and the other end of the second elastic member 444 abuts against the moving sleeve 442. The first elastic member 46 and the second elastic member 444 cooperate to drive the moving rod 441 and the moving sleeve 442 to be movably sealed.

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

[0073] In one embodiment, a base 49 is provided at the bottom of the inner cavity of the housing 41. An installation hole 491 is formed in the base 49. One end of the check rod 445 is threadedly installed in the installation hole 491; a guide groove 451 is formed at the top of the check rod 445, and one end of the movement rod 441 is movably inserted into the guide groove 451.

[0074] In some other embodiments, the connection between one end of the check rod 445 and the base 49 can also be achieved by welding, clamping or other means, which is not limited herein.

[0075] The first elastic member 46 and the second elastic member 444 are used for the movable seal between the movement sleeve 442 and the movement rod 441.

[0076] Specifically, a mating protrusion 4411 is provided at the top of the movement rod 441. The lower end surface of the mating protrusion 4411 is the first annular sealing surface 4412. The top of the movement 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 operates normally, the movement sleeve 442 is in a relatively static state. One end of the second elastic member 444 abuts against the movement sleeve 442, and the other end pulls down the movement rod 441, driving the first annular sealing surface 4412 of the movement rod 441 to closely fit with the second annular sealing surface 4421 of the movement sleeve 442 to disconnect the first channel 42 and the second channel 43.

[0078] That is to say, the first elastic member 46 has an upward elastic support for the movement sleeve 442, and the second elastic member 444 has a downward pulling force on the movement rod 441. Thus, the first annular sealing surface 4412 and the second annular sealing surface 4421 are closely fitted, and further the first channel 42 and the second channel 43 are disconnected.

[0079] When the pressure source 1 is overpressured, the medium in the pressure source 1 acts on the second annular sealing surface 4421 and drives the movement sleeve 442 to move downward to overcome the elastic forces of the first elastic member 46 and the second elastic member 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 communicated, and the medium in the first channel 42 flows through the second channel 43 into the primary circuit 5 for pressure reduction. As the pressure of the pressure source 1 decreases, the elastic forces of the first elastic member 46 and the second elastic member 444 gradually recover and finally return to the sealed state of the first annular sealing surface 4412 and the second annular sealing surface 4421, thus meeting the overpressure protection function of the pressure source 1.

[0080] When the pressure in the pressure source 1 drops, the medium in the primary loop 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 the pressure source 1 leaks and the pressure drops, the moving rod 441 compresses the second elastic member 444 and moves upward. The first annular sealing surface 4412 and the second annular sealing surface 4421 are separated, and the medium in the primary loop 5 flows to the pressure source 1 through the first channel 42 for pressure replenishment. During the process that the pressure in the pressure source 1 gradually rises to the rated pressure, the second elastic member 444 also gradually pulls the moving rod 441 downward until the first annular sealing surface 4412 abuts against the second annular sealing surface 4421 and returns to the initial sealing state, thereby satisfying the automatic pressure replenishment function of the 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 outside the moving rod 441 and is threadedly connected to the moving rod 441. One end of the second elastic member 444 abuts against the round nut 4413, and the round nut 4413 is used to adjust the initial pre-tightening force of the second elastic member 444.

[0083] That is, the top end of the second elastic member 444 abuts against the moving sleeve 442, and the bottom end abuts against the round nut 4413. Under the normal operation state of the primary loop 5, the medium in the second channel 43 cannot overcome the pre-tightening force of the first elastic member 46, and the moving sleeve 442 is relatively stationary. The top end of the second elastic member 444 is supported by the moving sleeve 442, and the bottom end applies an elastic force to the round nut 4413 and pulls the moving rod 441 downward so that the first annular sealing surface 4412 is in sealing abutment with the second annular sealing surface 4421.

[0084] Please continue to refer to Figure 3 , the middle part of the moving sleeve 442 has a convex portion 4422 that cooperates with the moving rod 441; first placement gaps 443 and second placement gaps 4423 are respectively formed between the moving sleeve 442 and the moving rod 441 on the opposite sides of the convex portion 4422, and the second placement gap 4423 communicates with the second channel 43.

[0085] Specifically, the moving rod 441 passes through the convex portion 4422. Because the convex portion 4422 protrudes, the inner diameter of the moving sleeve 442 at the position of the convex portion 4422 corresponds to that of the moving rod 441, and the inner diameter of the moving sleeve 442 on both sides of the convex portion 4422 is larger than the diameter of the moving rod 441, thereby forming the first placement gap 443 and the 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 guiding the flow, and is used to flow the medium in the second channel 43 to the side close to the mating protrusion 4411 through the second placement gap 4423.

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

[0087] That is to say, there are 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 is separated from the second annular sealing surface 4421, the first channel 42 communicates with the second channel 43; when the first annular sealing surface 4412 abuts against the second annular sealing surface 4421, the first channel 42 and the second channel 43 are disconnected.

[0088] Optionally, a limiting sleeve 47 is further provided in the inner cavity of the housing 41. The limiting sleeve 47 is sleeved outside the motion sleeve 442. One end of the limiting sleeve 47 extends to the top of the housing 41. An end cap 48 is further provided on the top of the housing 41. The end cap 48 covers the limiting sleeve 47 and is connected to the housing 41; the other end of the limiting sleeve 47 extends towards the inside of the accommodating chamber 411 and forms a check surface 4425. A check step 471 is provided at the bottom of the motion sleeve 442. The top surface of the check step 471 is located below the check surface 4425. The check surface 4425 is used to limit the upward path of the motion sleeve 442.

[0089] The end cap 48 and the limiting sleeve 47 can be connected by a threaded connector, or they can also be connected by clamping, welding or other methods, which are not limited here. The setting of the limiting sleeve 47 is used to limit the motion sleeve 442 to prevent the motion sleeve 442 from detaching from the housing 41.

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

[0091] When the first elastic member 46 is in a free non-loaded state, the check step 471 can limit the upward movement of the motion sleeve 442.

[0092] In actual application, the first elastic member 46 can select springs with different elastic moduli according to needs, which are not limited here.

[0093] In one embodiment, at least one flow groove 472 is circumferentially formed on the outer circumference of the limiting sleeve 47 along the motion rod 441. One end of the flow groove 472 extends to the top end 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 limit sleeve 47 limits the up-and-down sliding of the moving rod 441 to prevent the moving rod 441 from deflecting itself when sliding along the axis of the housing 41. In order to connect the first channel 42 and the second channel 43, a flow-through groove 472 is provided around the outer circumference of the moving rod 441 on the limit sleeve 47, and the first channel 42 is connected to the movable chamber 4424 by means of the flow-through groove 472.

[0095] Specifically, the number of the flow-through grooves 472 is at least two, and the at least two flow-through grooves 472 are evenly distributed around the outer circumference of the moving rod 441 in the circumferential direction.

[0096] By evenly distributing the at least two flow-through grooves 472 on the outer circumference of the moving rod 441, the flow stability of the medium flowing from the first channel 42 to the movable chamber 4424 can be improved.

[0097] Please refer to Figure 4 and Figure 5 , in an embodiment, the first channel 42 is located at the top of the accommodation chamber 411; the second channel 43 is opened on the side of the housing 41 and sequentially penetrates through the limit sleeve 47 and the moving sleeve 442 to communicate with the second placement gap 4423.

[0098] The setting positions of the first channel 42 and the second channel 43 are only examples here and are not limited herein.

[0099] Specifically, the end cap 48 is provided with a flow-through hole 481 along the axis of the housing 41, and the flow-through hole 481 is connected to the flow-through groove 472 and forms the first channel 42.

[0100] The pressure source 1 is connected to the first channel 42 through a pipeline, the first loop 5 is connected to the second pipeline through a pipeline, and a control mechanism 44 provided between the first channel 42 and the second channel 43 is used to control the on-off of the first channel 42 and the second channel 43, thereby meeting the functions of overpressure protection, automatic pressure compensation, and pressure maintenance of the pressure source 1.

[0101] In an embodiment, the receiving unit 2 is a storage tank for storing the medium flowing out of the first loop 5.

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

[0103] The control unit 6 can also be structures such as an electromagnetic valve and a control switch, which are not limited herein. The receiving unit 2 is used to store the medium flowing out of the first loop 5 or replenish the stored medium into the first loop 5.

[0104] The assembly process of an embodiment of the balance unit 4 is described as follows:

[0105] First step, thread-connect the base 49 and the check rod 445, and install the base 49 and the check rod 445 into the accommodation 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 axis of the housing 41 to avoid scratching the inner wall of the housing 41.

[0106] Second step, sleeved the first elastic member 46 on the outside of the check rod 445.

[0107] Third step, 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 member 444 into the first placement gap 443, and then install the round nut 4413 and tighten the round nut 4413 to the target pre-tightening force set by the second elastic member 444 to complete the assembly of the moving sleeve 442 and the moving rod 441.

[0108] Fourth step, sleeved the limit sleeve 47 on the outside of the moving sleeve 442.

[0109] Fifth step, place the housing 41 horizontally, and then install the assembled structures such as the limit sleeve 47, the moving sleeve 442 and the moving rod 441 into the housing 41. The bottom end of the moving sleeve 442 elastically abuts against the first elastic member 46, and then install the end cover 48 and the housing 41 with threaded connectors to finally complete the assembly of the balance unit 4.

[0110] The working principle of the balance unit 4 is described as follows:

[0111] When the primary circuit 5 is operating normally, the moving sleeve 442 is in a static state. The top end of the second elastic member 444 supports on the moving sleeve 442 and elastically drives the bottom end to act on the round nut 4413, and then pulls 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 open the second elastic member 444, so the first channel 42 and the second channel 43 are closed.

[0112] When there is overpressure on the side of the pressure source 1, the pressure on the first channel 42 side exceeds the pre-tightening forces of the first elastic member 46 and the second elastic member 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 movable sleeve 442 to drive the movable sleeve 442 to move downward. At this time, the movement rod 441 remains stationary under the support of the check rod 445. Then, the first annular sealing surface 4412 and the second annular sealing surface 4421 are separated, and the medium in the first channel 42 flows into the second channel 43 and finally flows into the primary loop 5. During the pressure relief process of the first channel 42, the elastic forces of the first elastic member 46 and the second elastic member 444 gradually recover. Eventually, after the pressure of the pressure source 1 drops to the rated value, the first elastic member 46 and the second elastic member 444 also recover to their initial pre-tightening forces, and the first annular sealing surface 4412 and the second annular sealing surface 4421 are resealed.

[0113] For example, it is set that when the pressure on the first channel 42 side reaches 14 MPa for the first elastic member 46 and the second elastic member 444, the first annular sealing surface 4412 and the second annular sealing surface 4421 are separated.

[0114] When the pressure on the side of the pressure source 1 exceeds 14 MPa, it is in an overpressure state, and the medium on the first channel 42 side will flow to the primary loop 5 side for pressure relief. When the pressure is relieved below 14 MPa, the first annular sealing surface 4412 and the second annular sealing surface 4421 are restored to the sealed state under the elastic forces of the first elastic member 46 and the second elastic member 444.

[0115] When the pressure of the pressure source 1 drops, due to the different pressure differences, the pressure of the medium in the second channel 43 overcomes the elastic force of the second elastic member 444, but at this time it does not overcome the elastic force of the first elastic member 46. As a result, the movable sleeve 442 remains stationary, and the medium in the second channel 43 flows into the second placement gap 4423 and acts on the first annular sealing surface 4412 to drive the movement rod 441 to move upward to separate the first annular sealing surface 4412 and the second annular sealing surface 4421. Then, the medium in the primary loop 5 can replenish the pressure to the pressure source 1. During the process of the pressure of the pressure source 1 gradually rising to the rated pressure, the elastic force of the second elastic member 444 also gradually recovers. Eventually, the first annular sealing surface 4412 and the second annular sealing surface 4421 are resealed.

[0116] It can be seen that on the second channel 43 side, only by overcoming the second elastic member 444 can the medium flow to the pressure source 1. Among them, it can be set that when the pressure difference is 2 MPa, the medium on the primary loop 5 side can overcome the elastic force of the second elastic member 444, and thus can automatically replenish the pressure from the primary loop 5 to the pressure source 1 side.

[0117] In the non-break accident condition, the pressure of the primary loop 5 may drop to a relatively low level. At this time, it is necessary to maintain the switch unit 3 closed, and the pressure of the pressure source 1 needs to be kept above a certain pressure.

[0118] The medium pressure on the pressure source 1 side of this application cannot overcome the elastic forces of the first elastic member 46 and the second elastic member 444. Therefore, 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 reduction of the primary loop 5 and can still be stabilized within the normal operating pressure range. This can also prevent the switch unit 3 connected to the primary loop 5 from being accidentally opened, thus avoiding the occurrence of a break accident in the primary loop 5.

[0119] In the accident condition of a break in the primary loop 5, the control unit 6 receives an opening signal and controls the pressure source 1 to be in an open state to discharge the pressure in the pressure source 1. When the pressure in the pressure source 1 drops to the opening pressure of the switch unit 3, the switch unit 3 opens, and the medium in the primary loop 5 can be discharged to the receiving unit 2 through the switch unit 3. At this time, the pressure in the pressure source 1 decreases, and the medium in the second channel 43 will act on the first annular sealing surface 4412 and flow to the second channel 43, and then flow to the receiving unit 2 through the control unit 6. In this way, two paths are formed to discharge the medium in the primary loop 5, meeting the requirements for the discharge time of the flowmeter after the accident.

[0120] This application also meets the water replenishment requirement from the receiving unit 2 to the 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 the receiving unit 2 can be replenished to the primary loop 5 through the switch unit 3.

[0121] In summary, the balance unit 4 provided in this application can meet the overpressure protection, pressure replenishment, and pressure holding functions of the pressure source 1 in the primary loop 5. Moreover, the balance unit 4 adopts a mechanical moving seal method, which can work in a high-temperature and high-pressure environment, and has a simple logic. It can meet the operation balance of the system without adding the design of other control systems, reducing the construction and maintenance costs of nuclear power plants.

[0122] The present invention also proposes a primary loop safety control method, which is implemented by using the above primary loop safety control system. The control method includes:

[0123] Receiving an opening signal and opening the control unit to depressurize the pressure source;

[0124] After the pressure source is depressurized until the switch unit opens, the medium in the primary loop flows to the receiving unit through two flow paths, namely the switch unit and the pressure source.

[0125] This application meets the requirement of discharging the medium in the primary loop through two flow paths under the condition of a break in the primary loop, meeting the requirements for the discharge flow rate and discharge time after the accident.

[0126] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installation", "connection", "attachment", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can also be a mechanical connection. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0127] The present application uses specific terms to describe the embodiments of the present application. Such as "an embodiment", "one embodiment", and / or "some embodiments" mean a certain feature, structure, or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that the "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more at different positions in this specification is not necessarily the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the present application can be appropriately combined.

[0128] Although the present invention is disclosed above in preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, all modifications, equivalent changes, and decorations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention fall within the protection scope defined by the claims of the present invention.

Claims

1. A primary circuit safety control system, characterized in that: include: A pressure source, a receiving unit, a switch unit and a balancing unit, wherein one end of the pressure source is connected to a circuit through the balancing unit, and the pressure source is also connected to the receiving unit and the switch unit respectively, one end of the switch unit is connected to the circuit, and the other end is connected to the receiving unit; wherein, The balancing unit includes a shell, a first channel and a second channel are provided on the shell, 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, and the control mechanism is used to control the on-off between the first channel and the second channel to meet the overpressure protection of the pressure source to the primary circuit side, the automatic pressure replenishment from the primary circuit to the pressure source side, and the pressure maintenance function of the pressure source.

2. The primary circuit safety control system according to claim 1, characterized in that: A containing chamber is formed in the housing between the first channel and the second channel, and the control mechanism is disposed in the containing chamber; The control mechanism comprises a movable movement rod and a movement sleeve, wherein the movement rod is sleeved in the movement sleeve and slides with the movement sleeve along the axis of the movement sleeve, and the movement sleeve is sleeved in the accommodating chamber and slides with the shell along the axis of the shell; The movement sleeve and the movement rod are movably sealed to connect or close the first channel and the second channel.

3. The primary circuit safety control system according to claim 2, characterized in that: A check rod is provided at the bottom of the movement rod, a first elastic member is sleeved on the outer side of the check rod, and the bottom end of the movement sleeve abuts against the top end of the first elastic member; A first placement gap is provided between the movement rod and the movement sleeve, a second elastic member is provided in the first placement gap, the second elastic member is sleeved outside the movement rod and one end of the second elastic member is fixedly connected to the movement rod, and the other end of the second elastic member abuts against the movement sleeve; The first elastic member and the second elastic member cooperate to drive the movement rod and the movement sleeve to move and seal.

4. The primary circuit safety control system according to claim 3, characterized in that: The top of the movement rod is provided with a matching protrusion, the lower end surface of the matching protrusion is a first annular sealing surface, and the top of the movement sleeve is provided with a second annular sealing surface corresponding to the first annular sealing surface; When the primary circuit operates normally, the moving sleeve is in a stationary state, and the second elastic member pulls the moving rod downward until the first annular sealing surface abuts against the second annular sealing surface for sealing; When the first channel is over-pressured, the medium in the pressure source acts on the second annular sealing surface and drives the moving sleeve to compress the first elastic member and the second elastic member 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 primary circuit acts on the first annular sealing surface through the second channel and drives the moving rod upward to separate the first annular sealing surface and the second annular sealing surface.

5. The primary circuit safety control system according to claim 3, characterized in that: A round nut is provided at the bottom of the movement rod. The round nut is sleeved on the outside of the movement rod and threadedly connected to the movement rod. One end of the second elastic member abuts against the round nut. The round nut is used to adjust the initial preload force of the second elastic member.

6. The primary circuit safety control system according to claim 3, characterized in that: The middle part of the sports sleeve has a protrusion that matches with the sports rod; The moving sleeve forms the first placement gap and the second placement gap between the moving rod and the two opposite sides of the protrusion, respectively, and the second placement gap is communicated with the second channel.

7. The primary circuit safety control system according to claim 6, characterized in that: An active chamber is formed between the top of the sports sleeve and the matching protrusion, the first channel is communicated with the active chamber, and the second channel is communicated with the active chamber via the second placement gap.

8. The primary circuit safety control system according to claim 7, characterized in that: The inner cavity of the shell is also provided with a limiting sleeve, the limiting sleeve is arranged on the outside of the sports sleeve, one end of the limiting sleeve extends to the top of the shell, the top of the shell is also provided with an end cover, the end cover is covered on the limiting sleeve and connected to the shell; The other end of the limiting sleeve extends toward the inner side of the accommodating chamber and is formed with a non-return surface. The bottom of the moving sleeve is provided with a non-return step, the top surface of the non-return step is located below the non-return surface, and the non-return surface is used to limit the upward path of the moving sleeve.

9. The primary circuit safety control system according to claim 8, characterized in that: The limiting sleeve is provided with at least one flow groove along the outer circumference of the movement 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 activity chamber.

10. The primary circuit safety control system according to claim 9, characterized in that: The number of the flow grooves is at least two, and at least two of the flow grooves are evenly distributed around the outer circumference of the movement rod.

11. The primary circuit 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 at the side of the shell and passes through the limiting sleeve and the moving sleeve in sequence to communicate with the second placement gap.

12. The primary circuit safety control system according to claim 8, characterized in that: The end cover is provided with a flow hole along the axial direction of the shell, and the flow hole is connected with the flow groove to form the first channel.

13. The primary circuit safety control system according to claim 3, characterized in that: A base is provided at the bottom of the inner cavity of the shell, a mounting hole is provided on the base, and one end of the check rod is threadedly installed in the mounting hole; A guide groove is provided on the top of the check rod, and one end of the movement rod is movably inserted into the guide groove.

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

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

16. A primary circuit safety control method, characterized in that: The control method is implemented by using a primary circuit safety control system as described in any one of claims 1 to 15, and the control method comprises: receiving an opening signal and opening a control unit to relieve pressure from the pressure source; After the pressure source is depressurized until the switch unit is opened, the medium in the primary circuit flows to the receiving unit through the switch unit and the pressure source.

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