A valve assembly for primary circuit pressure relief and discharge

Abstract

This invention provides a valve assembly for primary loop depressurization and discharge, comprising: a main valve, a pilot valve, and first and second control valves. The main valve has a sealed cavity and a valve cavity communicating with the primary loop coolant and the atmosphere. The pilot valve has a first sealed cavity, a first channel, a second channel, and a second sealed cavity arranged sequentially. The outlets of the first and second channels are both connected to the sealed cavity of the main valve. The outlets of the first and second control valves are respectively connected to the first and second sealed cavities. The first and second control valves, through on / off combinations, control the medium entering the first and second sealed cavities, thereby controlling the sliding of the pilot valve core to open or close the first and second channels, and further controlling the medium entering the sealed cavity of the main valve, thereby controlling the sliding of the main valve core to open or close the main valve cavity. This invention enables the main valve to automatically open without external energy input under primary loop conditions and to maintain an open state at all times. It also enables manual opening of the main valve and ensures effective isolation of the main valve during reactor shutdown and refueling.

Description

Technical Field

[0001] This invention relates to the field of nuclear power safety technology, and more specifically to a valve assembly for primary circuit depressurization and discharge. Background Technology

[0002] In pressurized water reactor nuclear power plants, the reactor coolant system, as one of the most important barriers to contain radioactive materials, is directly related to the safety performance of the nuclear power plant.

[0003] Nuclear power plant reactor coolant systems operate at high pressures during normal operation. To prevent overpressure in the event of an accident and to ensure continuous cooling of the reactor core after an accident, overpressure protection valves and primary loop pressure relief valves are required in the reactor coolant system. Currently, the main types of overpressure protection valves and pressure relief valves used are as follows:

[0004] (1) Spring-loaded safety valve: It automatically opens to relieve pressure when the system pressure reaches the set pressure of the safety valve. It is currently the most widely used overpressure protection valve in process systems. The characteristic of this type of safety valve is that it can only perform overpressure protection function. When the pressure is lower than the opening pressure, the valve closes and cannot be opened manually.

[0005] (2) Pilot-operated safety valves, similar to spring-loaded safety valves, automatically open to relieve pressure when the system pressure reaches the set pressure of the safety valve. Compared with spring-loaded safety valves, they are more reliable and are currently mainly used in pressure regulator safety valves. This type of safety valve requires less power to open. The disadvantage is that when manual opening is required, it needs to be kept energized at all times, and it cannot maintain the open state at low pressure.

[0006] (3) Electric or pneumatic isolation valves, which open or close the valve by means of power supply when the system pressure reaches the design requirement. The feature of this type of valve is that it can be opened at any time and maintains its original state after the power is lost. The disadvantage is that it requires a large amount of power (electric power or pneumatic power) to open.

[0007] (4) Explosive valve: The valve opening signal triggers the explosive unit inside the valve, generating high-pressure gas that drives the piston inside the valve to move. During the impact motion, the shear cover of the valve's flow path can be cut off, thereby connecting the valve's inlet and outlet, achieving the safety function of system depressurization. The characteristic of this type of valve is that once opened, it remains open and cannot be reversed. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art by providing a valve group for primary loop depressurization and discharge, which can realize the automatic opening of the main valve without external energy input under the condition that the primary loop meets the requirements and maintain the open state at all times, and can realize the manual opening of the main valve and ensure the effective isolation of the main valve during normal operation and material replacement.

[0009] The technical solution adopted to solve the technical problem of this invention is:

[0010] This invention provides a valve assembly for primary circuit pressure relief and discharge, comprising: a main valve and a control valve assembly. The main valve includes: a main valve body and a main valve core. The main valve body has a main sealing cavity and a main valve cavity. The main valve cavity is used to connect the primary circuit coolant and the atmosphere. One end of the main valve core is located in the main sealing cavity, and the other end is located in the main valve cavity. The main valve core is capable of sliding within the main valve body under the pressure of the medium entering the main sealing cavity to open or close the main valve cavity.

[0011] The control valve assembly includes a pilot valve, a first control valve, and a second control valve.

[0012] The pilot valve includes a pilot valve body and a pilot valve core. The pilot valve body has a first sealing cavity, a first channel, a second channel, and a second sealing cavity arranged sequentially. The pilot valve core includes a drive structure and a valve core structure. One end of the drive structure is located in the first sealing cavity, and the other end is located in the second sealing cavity. The valve core structure is connected to the drive structure, with one end located in the first channel and the other end located in the second channel. The drive structure can slide within the pilot valve body under the pressure difference between the medium entering the first sealing cavity and the medium entering the second sealing cavity, thereby driving the valve core structure to open the first channel and close the second channel, or close the first channel and open the second channel. The outlets of both the first and second channels are connected to the main sealing cavity.

[0013] The first control valve has a first input port, a second input port, and a first output port. The first output port is connected to a first sealing cavity, the first input port is connected to a primary circuit volume control box or a pressure relief box, and the second input port is connected to a constant pressure source.

[0014] The second control valve has a third input port, a fourth input port, and a second output port. The second output port is connected to the inlet of the first channel and the second sealed cavity, respectively. The third input port is connected to a constant pressure source, and the fourth input port is connected to the primary coolant circuit.

[0015] When the first control valve is energized, its first output port is connected to the first input port and disconnected from the second input port. When the first control valve is de-energized, its first output port is connected to the second input port and disconnected from the first input port.

[0016] When the second control valve is energized, its second output port is connected to the third input port and disconnected from the fourth input port. When the second control valve is de-energized, its second output port is connected to the fourth input port and disconnected from the third input port.

[0017] The pressure setpoint P of the medium entering the main sealing cavity opens the main valve. 0main Satisfy: P0 < P0main <Pacc, where P0 is atmospheric pressure and Pacc is the pressure of the constant pressure source.

[0018] The medium entering the second sealed chamber opens the pilot valve's pressure setpoint P. 0twin Satisfying: Pacc × A1 = P 0twin ×A2, where Pacc is the pressure of the constant pressure source, A1 is the cross-sectional area of ​​the first pilot piston, A2 is the cross-sectional area of ​​the second pilot piston, and A2 < A1.

[0019] Optionally, the first control valve includes a first control valve body, a first control piston assembly, and a first solenoid valve.

[0020] The first control valve body has a first main chamber and a first side chamber. A first control piston assembly is disposed in the first main chamber, and a first solenoid valve is disposed in the first side chamber. A first input port, a second input port, and a first output port are all opened on the first control valve body and are all in communication with the first main chamber. The first control piston assembly includes a first control piston rod and a plurality of first control pistons fixed on the first control piston rod. The plurality of first control pistons are sequentially and slidably sealed in the first main chamber along the axial direction of the first control piston rod to divide the first main chamber into a plurality of first sub-chambers. One end of the first control piston rod extends out of the first main chamber and is connected to the first solenoid valve.

[0021] The first output port is located on one side of the first control piston rod in the radial direction, and the first input port and the second input port are both located on the other side of the first control piston rod in the radial direction. When the first solenoid valve is energized, it can drive the first control piston assembly to move axially to the first output port, which communicates with the first input port through one of the first sub-cavities, while the second input port is located in the other adjacent first sub-cavity, so that the first control valve is in the first energized state. When the first solenoid valve is de-energized, it can drive the first control piston assembly to move axially in the reverse direction to the first output port, which communicates with the second input port through one of the first sub-cavities, while the first input port is located in the other adjacent first sub-cavity, so that the first control valve is in the first de-energized state.

[0022] The second control valve includes a second control valve body, a second control piston assembly, and a second solenoid valve.

[0023] The second control valve body has a second main chamber and a second side chamber. A second control piston assembly is located in the second main chamber, and a second solenoid valve is located in the second side chamber. A third input port, a fourth input port, and a second output port are all located on the second control valve body and communicate with the second main chamber. The second control piston assembly includes a second control piston rod and multiple second control pistons fixed to the second control piston rod. These multiple second control pistons are sequentially and slidably disposed within the second main chamber along the axial direction of the second control piston rod to divide the second main chamber into multiple second sub-chambers. One end of the second control piston rod extends out of the second main chamber and is connected to the second solenoid valve.

[0024] The second output port is located on one side of the second control piston rod in the radial direction, and the third and fourth input ports are both located on the other side of the second control piston rod in the radial direction. When the second solenoid valve is energized, it can drive the second control piston assembly to move axially to the second output port, which communicates with the third input port through one of the second sub-cavities. At the same time, the fourth input port is located in the other adjacent second sub-cavity, so that the second control valve is in the second energized state. When the second solenoid valve is de-energized, the second control piston assembly can move axially in the reverse direction to the second output port, which communicates with the fourth input port through one of the second sub-cavities. At the same time, the third input port is located in the other adjacent second sub-cavity, so that the second control valve is in the second de-energized state.

[0025] Optionally, the first solenoid valve includes a first suction cup, a first coil, and a first return spring. The first coil is fixed to the outer end wall of the first main chamber, the first suction cup is fixed to the end of the first control piston rod that extends into the first side chamber, and the first return spring is connected between the cavity wall of the first side chamber and the first suction cup.

[0026] When the first solenoid valve is energized, the first suction cup moves toward the first coil until it is fixed to it, so as to drive the first control piston assembly to move axially to the first control valve in the first energized state, and the first return spring is stretched. When the first solenoid valve is de-energized, the first suction cup is disconnected from the first coil and the first return spring is reset, so as to drive the first control piston assembly to move axially to the first control valve in the first de-energized state.

[0027] The second solenoid valve includes a second suction cup, a second coil, and a second return spring. The second coil is fixed to the outer end wall of the second main chamber, the second suction cup is fixed to the end of the second control piston rod that extends into the second side chamber, and the second return spring is connected between the cavity wall of the second side chamber and the second suction cup.

[0028] When the second solenoid valve is energized, the second suction cup moves toward the second coil until it is fixed to it, so as to drive the second control piston assembly to move axially to the second control valve in the second energized state, and the second return spring is stretched. When the second solenoid valve is de-energized, the second suction cup is disconnected from the second coil and the second return spring is reset, so as to drive the second control piston assembly to move axially to the second control valve in the second de-energized state.

[0029] Optionally, the control valve assembly is provided in multiple sets, and the first channel outlet and the second channel outlet of the multiple sets of control valve assemblies are both connected to the main sealing cavity of the main valve.

[0030] The first control valve has multiple first solenoid valves, and the first suction cups of the multiple first solenoid valves are all fixedly connected to the first control piston rod.

[0031] The second control valve has multiple second solenoid valves, and the second suction cups of the multiple second solenoid valves are all fixedly connected to the second control piston rod.

[0032] The main valve core includes a main piston assembly and a main spring. The main piston assembly includes a main piston rod, a main piston, and a valve disc. The main piston rod is slidably disposed within the main valve body. The main piston is fixed on the main piston rod and located within the main sealing cavity. The valve disc is fixed on the main piston rod and located within the main valve cavity. The main spring is located within the main sealing cavity and compressed between the main piston and the bottom wall of the main valve cavity.

[0033] Optionally, the main valve chamber is located in the lower part of the main sealing chamber. The main valve body has a valve inlet and a valve outlet that communicate with the main valve chamber. The valve inlet is located at the bottom of the main valve body and is used to connect with the primary coolant circuit. The valve outlet is located on the side of the main valve body and is used to connect with the atmosphere. The main piston assembly is vertically slidable within the main valve body.

[0034] The pressure setpoint P of the medium entering the main sealing cavity opens the main valve. 0main Also satisfies: P 0main ×(A1-A2)+G=F, where A1 is the cross-sectional area of ​​the main piston, A2 is the cross-sectional area of ​​the valve disc, G is the weight of the main piston assembly, and F is the elastic force of the main spring when the main valve is closed.

[0035] Optionally, the outer diameter of the valve disc gradually decreases from top to bottom, so that the outer wall of the valve disc forms a first conical surface.

[0036] The valve inlet is equipped with a nozzle, and the upper part of the inner wall of the nozzle has a second conical surface that mates with the first conical surface. When the main piston assembly moves down to mate with the first and second conical surfaces, the valve disc closes the valve inlet.

[0037] Optionally, the main valve body includes, from bottom to top, a main valve housing, a lower valve seat, and an upper valve seat that are sequentially fixed together, and the inner cavity of the main valve housing forms the main valve cavity.

[0038] The top surface of the lower valve seat has a first groove, the lower part of the upper valve seat extends into the first groove and is sealed to the groove wall of the first groove, and the bottom surface of the upper valve seat has a second groove, the groove wall of the second groove and the bottom wall of the first groove enclose to form the main sealing cavity.

[0039] The main piston rod includes a working section and a positioning section. The lower end of the working section is fixedly connected to the valve disc, and its upper end passes through the lower valve seat and extends into the main sealing cavity, where it is fixedly connected to the main piston. The main spring passes through the working section.

[0040] The upper part of the upper valve seat has a sealed exhaust chamber, and the top of the upper valve seat is provided with a valve cover for opening or sealing the exhaust chamber. The lower end of the positioning section is fixed to the piston, and its upper end passes through the lower part of the upper valve seat and extends into the exhaust chamber.

[0041] Optionally, the drive structure includes a first pilot piston, a second pilot piston, and a pilot piston rod. The pilot piston rod is axially slidable within the pilot valve body and connected between the first and second pilot pistons. The first pilot piston is slidably and sealingly disposed within a first sealing cavity, and the second pilot piston is slidably and sealingly disposed within a second sealing cavity.

[0042] The valve core structure includes a first pilot valve, a second pilot valve, and a pilot valve stem. The pilot valve stem is arranged parallel to and connected to the pilot piston rod. It is axially slidable in the pilot valve body and connected between the first pilot valve and the second pilot valve. The first pilot valve is located in a first channel and is used to open or close the first channel. The second pilot valve is located in a second channel and is used to open or close the second channel.

[0043] Optionally, the first pilot valve includes a first valve plate and a first valve core assembly. The first valve plate is fixed in the first channel and closes the first channel, and has a first valve hole. The first valve core assembly is slidably disposed in the first channel and cooperates with the first valve hole.

[0044] The second pilot valve includes a second valve plate and a second valve core assembly. The second valve plate is fixed in the second channel and closes the second channel, and has a second valve hole. The second valve core assembly is slidably disposed in the second channel and engages with the second valve hole.

[0045] The pilot valve stem is connected to the first valve core assembly and the second valve core assembly. When it moves axially, it drives the first valve core assembly to open the first valve hole and drives the second valve core assembly to close the second valve hole, or drives the first valve core assembly to close the first valve hole and drives the second valve core assembly to open the second valve hole.

[0046] Optionally, the first channel includes a first inlet section, a first pilot valve chamber, and a first outlet section connected in sequence. The first pilot valve is located within the first pilot valve chamber, which has space for the first valve core assembly to slide.

[0047] The second channel includes a second inlet section, a second pilot valve chamber, and a second outlet section connected in sequence. The second outlet section is connected to the first outlet section. The second pilot valve is located in the second pilot valve chamber, which has space for the second valve core assembly to slide.

[0048] Optionally, the pilot piston rod and the pilot valve rod are connected by a pilot dial, and the pilot valve body is provided with a slot that allows the pilot dial to move axially along the pilot piston rod.

[0049] This invention combines a main valve, a pilot valve, and two control valves to form a valve assembly for primary circuit pressure relief and discharge. The main valve's main valve body has a sealed cavity and a valve cavity, with its valve core sliding within the main valve body. The valve core can slide within the main valve body under the pressure of the medium entering the sealed cavity to open or close the valve cavity. The pilot valve's pilot valve body has a first sealed cavity, a first channel, a second channel, and a second sealed cavity arranged sequentially. Its pilot valve core slides within the pilot valve body and can slide within the main valve body under the pressure of the medium entering the first sealed cavity and the medium entering the second sealed cavity. Under the influence of a strong differential force, the first channel opens and the second channel closes, or the first channel closes and the second channel opens. The outlets of both the first and second channels are connected to the main sealing cavity. The first output port of the first control valve is connected to the first sealing cavity, its first input port is connected to the primary circuit volume control box or pressure relief box, and its second input port is connected to the constant pressure source. The second output port of the second control valve is connected to the inlet of the first channel and the second sealing cavity, respectively, its third input port is connected to the constant pressure source, and its fourth input port is connected to the primary circuit coolant. The main valve's opening setpoint P... 0main Satisfy: P0 < P 0main <Pacc, the pressure setpoint P of the pilot valve 0twin Satisfying: Pacc × A1 = P 0twin ×A2, A2<A1, therefore:

[0050] When this valve assembly is in standby mode (both the first and second control valves are de-energized), with normal primary circuit pressure (approximately 15.5 MPa), the first sealing chamber of the pilot valve is under constant pressure (e.g., the pressure in the injection tank is approximately 4-5 MPa), while the second sealing chamber is under primary circuit pressure. The pilot valve core moves upward to open the first channel, thus the pressure source entering the main sealing chamber of the main valve is a primary circuit pressure, significantly greater than the main valve opening setpoint P. 0main The main valve closes, thus isolating the main valve during normal operation of the primary circuit. In the event of a primary circuit fault, the pressure drop becomes less than the pilot valve's pressure setpoint P. 0twin When the pilot valve core moves down to open the second channel, the pressure source entering the main sealing chamber of the main valve is the primary circuit volume control box or pressure relief box (atmospheric pressure P0), which is less than the main valve opening set value P. 0main The main valve opens automatically, thus ensuring that when the primary circuit pressure is abnormal (P...rcs <P 0twin The main valve opens automatically without any energy input (because both the first and second control valves are de-energized, and the main valve opens automatically when the primary circuit pressure meets the requirements).

[0051] In situations where the main valve needs to be manually opened, the first solenoid valve is de-energized and the second solenoid valve is energized. At this time, the first sealing chamber of the pilot valve is under constant pressure (e.g., the pressure in a safety injection tank is approximately 4-5 MPa), and the second sealing chamber is also under constant pressure (e.g., the pressure in a safety injection tank is approximately 4-5 MPa). The medium entering the second sealing chamber opens the pilot valve at its pressure setpoint P. 0twin The pressure is greater than the constant pressure source pressure Pacc (i.e., A2 < A1), thus the pilot valve core is in a depressed state, the second channel opens, and therefore the pressure source entering the main sealing chamber of the main valve is the primary loop volume control box or pressure relief box (atmospheric pressure P0), which is less than the main valve opening set value P. 0main The main valve is open;

[0052] When shutting down the reactor for refueling (requiring the primary loop pressure to drop to atmospheric pressure) and not wanting the main valve to open, first energize the first solenoid valve and de-energize the second solenoid valve. At this time, the first sealing chamber of the pilot valve contains the primary loop volume control box or pressure relief box (atmospheric pressure P0), and the second sealing chamber contains the primary loop pressure. The primary loop pressure drops to the pilot valve's pressure setpoint P. 0twin The following (while in standby mode, the pressure in the primary circuit drops to the pilot valve's pressure setpoint P) 0twin (Main valve already open), main valve opening setpoint P 0main Previously, the pilot valves were all in the upward position to open the first channel. The pressure source entering the main sealing chamber of the main valve was the primary loop. During this stage, the main valve was in the closed position, thus achieving high-pressure isolation of this valve group during the refueling shutdown. If the pressure in the primary loop continues to drop, the main valve will open, and thus the pressure in the primary loop will drop to the main valve opening set value P. 0main Previously, both the first and second solenoid valves were energized. At this time, the first sealing chamber of the pilot valve was at the pressure of the primary circuit volume control box or pressure relief box (atmospheric pressure P0), and the second sealing chamber was at the pressure of a constant pressure source (such as the pressure of a safety injection box, which is about 4-5 MPa). The pilot valve was in the upward position to open the first channel. The pressure source entering the main sealing chamber of the main valve was a constant pressure source (such as the pressure of a safety injection box, which is about 4-5 MPa), which was greater than the main valve opening set value P. 0main Even if the primary circuit pressure drops to the main valve opening set value P, 0main Under these conditions, all main valves are in the closed state, thereby achieving low-pressure isolation of this valve group during the shutdown and refueling period.

[0053] This pressure relief valve assembly design meets the primary circuit pressure relief requirements of subsequent Hualong models while possessing the following technical advantages:

[0054] 1) In standby mode, it automatically starts when the pressure of the primary circuit meets the requirements, without requiring any energy input, and has high reliability.

[0055] 2) Once the valve opens automatically, it can remain in the open state without requiring any power supply, thus ensuring long-term pressure relief in the primary circuit.

[0056] 3) By combining different solenoid valves, the valve can be reliably isolated in any state, and can also be manually opened in any state. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the passive core cooling system;

[0058] Figure 2 This is a schematic diagram of the valve assembly for primary circuit depressurization and discharge provided in Embodiment 1 of the present invention;

[0059] Figure 3 A schematic diagram of the main valve;

[0060] Figure 4 This is a schematic diagram of the pilot valve.

[0061] In the picture:

[0062] 1. Pilot valve; 11. First valve seat; 12. Second valve seat; 13. Intermediate valve seat; 14. First valve plate; 15. First pilot piston; 16. Pilot piston rod; 17. First sealing cavity; 18. First conduit; 19. Second valve plate; 110. Second pilot piston; 111. Pilot valve rod; 112. Second sealing cavity; 113. Second conduit; 114. Output pipe; 115. First input pipe; 116. Second input pipe; 117. First valve core assembly; 118. Second valve core assembly; 119. Pilot dial; 120. First pilot valve cavity; 121. Second pilot valve cavity; 122. Slot;

[0063] 2. Main valve; 21. Main valve body; 22. Lower valve seat; 23. Upper valve seat; 24. Main valve chamber; 25. Main piston; 26. Main spring; 27. Working section; 28. Valve disc; 29. ​​Valve inlet; 210. Nozzle; 211. Valve outlet; 212. Exhaust chamber; 213. Positioning section; 214. Pilot guide; 215. Main sealing chamber;

[0064] 3. First control valve; 31. First control valve body; 311. First main chamber; 312. First side chamber; 313. First input port; 314. Second input port; 315. First output port; 32. First control piston assembly; 321. First control piston rod; 322. First control piston; 33. First solenoid valve; 331. First suction cup; 332. First coil; 333. First return spring;

[0065] 4. Second control valve; 41. Second control valve body; 411. Second main chamber; 412. Second side chamber; 413. Third input port; 414. Fourth input port; 415. Second output port; 42. Second control piston assembly; 421. Second control piston rod; 422. Second control piston; 43. Second solenoid valve; 431. Second suction cup; 432. Second coil; 433. Second return spring. Detailed Implementation

[0066] The technical solutions of the invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without creative effort are within the scope of the invention.

[0067] In the description of this invention, it should be noted that the use of terms such as "above" to indicate orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings and is only for the purpose of facilitating and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0068] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0069] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection," "setting," "installation," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0070] This invention provides a valve assembly for primary circuit pressure relief and discharge, comprising: a main valve and a control valve assembly. The main valve includes: a main valve body and a main valve core. The main valve body has a main sealing cavity and a main valve cavity. The main valve cavity is used to connect the primary circuit coolant and the atmosphere. One end of the main valve core is located in the main sealing cavity, and the other end is located in the main valve cavity. The main valve core is capable of sliding within the main valve body under the pressure of the medium entering the main sealing cavity to open or close the main valve cavity.

[0071] The control valve assembly includes a pilot valve, a first control valve, and a second control valve.

[0072] The pilot valve includes a pilot valve body and a pilot valve core. The pilot valve body has a first sealing cavity, a first channel, a second channel, and a second sealing cavity arranged sequentially. The pilot valve core includes a drive structure and a valve core structure. One end of the drive structure is located in the first sealing cavity, and the other end is located in the second sealing cavity. The valve core structure is connected to the drive structure, with one end located in the first channel and the other end located in the second channel. The drive structure can slide within the pilot valve body under the pressure difference between the medium entering the first sealing cavity and the medium entering the second sealing cavity, thereby driving the valve core structure to open the first channel and close the second channel, or close the first channel and open the second channel. The outlets of both the first and second channels are connected to the main sealing cavity.

[0073] The first control valve has a first input port, a second input port, and a first output port. The first output port is connected to a first sealing cavity, the first input port is connected to a primary circuit volume control box or a pressure relief box, and the second input port is connected to a constant pressure source.

[0074] The second control valve has a third input port, a fourth input port, and a second output port. The second output port is connected to the inlet of the first channel and the second sealed cavity, respectively. The third input port is connected to a constant pressure source, and the fourth input port is connected to the primary coolant circuit.

[0075] When the first control valve is energized, its first output port is connected to the first input port and disconnected from the second input port. When the first control valve is de-energized, its first output port is connected to the second input port and disconnected from the first input port.

[0076] When the second control valve is energized, its second output port is connected to the third input port and disconnected from the fourth input port. When the second control valve is de-energized, its second output port is connected to the fourth input port and disconnected from the third input port.

[0077] The pressure setpoint P of the medium entering the main sealing cavity opens the main valve. 0main Satisfy: P0 < P 0main <Pacc, where P0 is atmospheric pressure and Pacc is the pressure of the constant pressure source.

[0078] The medium entering the second sealed chamber opens the pilot valve's pressure setpoint P. 0twin Satisfying: Pacc × A1 = P 0twin ×A2, where Pacc is the pressure of the constant pressure source, A1 is the cross-sectional area of ​​the first pilot piston, A2 is the cross-sectional area of ​​the second pilot piston, and A2 < A1.

[0079] Example 1:

[0080] like Figure 2 As shown, this embodiment provides a valve assembly for primary circuit pressure relief and discharge, including: a main valve 2 and a control valve assembly. The main valve 2 includes: a main valve body and a main valve core. The main valve body has a main sealing cavity 215 and a main valve cavity 24. The main valve cavity 24 is used to connect the primary circuit coolant and the atmosphere. One end of the main valve core is located in the main sealing cavity 215, and the other end is located in the main valve cavity 24. The main valve core can slide within the main valve body under the pressure of the medium entering the main sealing cavity 215 to open or close the main valve cavity 24.

[0081] The control valve assembly includes a pilot valve 1, a first control valve 3, and a second control valve 4.

[0082] Pilot valve 1 includes a pilot valve body and a pilot valve core. The pilot valve body has a first sealing cavity 17, a first channel, a second channel, and a second sealing cavity 112 arranged sequentially. The pilot valve core includes a drive structure and a valve core structure. One end of the drive structure is located in the first sealing cavity 17, and the other end is located in the second sealing cavity 112. The valve core structure is connected to the drive structure, with one end located in the first channel and the other end located in the second channel. The drive structure can slide within the pilot valve body under the pressure difference between the medium entering the first sealing cavity 17 and the medium entering the second sealing cavity 112, thereby driving the valve core structure to open the first channel and close the second channel, or close the first channel and open the second channel. The outlets of both the first and second channels are connected to the main sealing cavity 215.

[0083] The first control valve 3 has a first input port 313, a second input port 314, and a first output port 315. The first output port 315 is connected to the first sealing cavity 17, the first input port 313 is connected to the primary circuit volume control box or pressure relief box, and the second input port 314 is connected to a constant pressure source.

[0084] The second control valve 4 has a third input port 413, a fourth input port 414, and a second output port 415. The second output port 415 is connected to the inlet of the first channel and the second sealing cavity 112, respectively. The third input port 413 is connected to a constant pressure source, and the fourth input port 414 is connected to the primary coolant circuit.

[0085] The first control valve 3 has a first energized state where the first output port 315 is connected to the first input port 313 and disconnected from the second input port 314, and a first de-energized state where the first output port 315 is connected to the second input port 314 and disconnected from the first input port 313. It can switch between the first energized state and the first de-energized state to change the medium entering the first sealed cavity 17 and its pressure.

[0086] The second control valve 4 has a second energized state where the second output port 415 is connected to the third input port 413 and disconnected from the fourth input port 414, and a second de-energized state where the second output port 415 is connected to the fourth input port 414 and disconnected from the third input port 413. It can switch between the second energized state and the second de-energized state to change the medium entering the second sealed cavity 112 and its pressure.

[0087] The pressure set value P of the medium entering the main sealing cavity 215 opens the main valve 2. 0main Satisfy: P0 < P 0main <Pacc, where P0 is atmospheric pressure and Pacc is the pressure of the constant pressure source.

[0088] The medium entering the second sealing chamber 112 opens the pressure set value P of the pilot valve 1. 0twin Satisfying: Pacc × A1 = P 0twin ×A2, where Pacc is the pressure of the constant pressure source, A1 is the cross-sectional area of ​​the first pilot piston 15, A2 is the cross-sectional area of ​​the second pilot piston 110, and A2 < A1.

[0089] Passive core cooling is one of the technical routes for third-generation pressurized water reactor nuclear power technology. Taking the AP1000 as an example, such as... Figure 1 As shown, its passive core cooling system includes:

[0090] Core makeup water tank: The pressure is the same as that of the primary loop (15.5MPa), and it is responsible for the function of making the core makeup water under high pressure.

[0091] Water supply tank: around 4-5MPa, responsible for water replenishment when the pressure is below 4-5MPa.

[0092] IRWST (Gravity Water Tank): The pressure is the same as atmospheric pressure, as low as 0.1MPa, and it is responsible for replenishing water when the pressure of the primary circuit drops to normal pressure.

[0093] ADS valves (burst valves): They perform the pressure relief function, gradually reducing the primary circuit pressure from 15.5 to atmospheric pressure, enabling the three water replenishment measures mentioned above to be activated in sequence, ultimately achieving IRWST gravity water injection, which is necessary for long-term core cooling and ensuring long-term safety.

[0094] To avoid problems caused by excessively rapid depressurization, ADS1-3+ADS4 are put into operation in sequence.

[0095] Among them, ADS1-3 has a relatively low depressurization speed and mainly undertakes the function of depressurization under high pressure.

[0096] The ADS4 has a relatively fast depressurization speed. To avoid the impact caused by excessively fast depressurization, it can only be opened after the primary circuit pressure is below a certain threshold (approximately 8-9 MPa).

[0097] After ADS4 is activated, the primary circuit pressure can quickly drop to the pressure of the injection tank, and eventually drop to the IRWST injection pressure.

[0098] Current ADS technology primarily employs rupture valves and electric valves. Both types of valves open by outputting an electrical signal when the primary circuit pressure drops to a threshold. Electric valves, due to their large size and high energy requirement for opening, present numerous challenges in the design of pressure relief systems. Rupture valves offer advantages such as good sealing and low opening power, but certain difficulties remain regarding reliability data.

[0099] The Hualong series of turbines adopts a passive safety system design concept, employing a passive safety system to address design baseline accidents. Under this design concept, a mature and reliable primary circuit depressurization system is required, capable of promptly and effectively reducing the primary circuit pressure to the gravity injection head. Therefore, there is an urgent need to explore new valve design solutions beyond burst valves and electric valves to achieve the primary circuit depressurization function and meet the application scenario requirements of the Hualong series of turbines.

[0100] The pressure relief valve assembly of the present invention is mainly used to replace the function of ADS-4, that is, when the primary circuit pressure drops to 8-9MPa, it can automatically open, and the opening speed is required to be fast, without power or with little power consumption (it can be powered by a battery to increase reliability after power loss).

[0101] This invention combines a main valve 2, a pilot valve 1, and two control valves to form a valve assembly for primary circuit pressure relief and discharge. The main valve 2 has a main valve body with a sealed cavity 215 and a valve chamber 24. Its valve core slides within the main valve body and can slide within the main valve body under the pressure of the medium entering the sealed cavity 215 to open or close the valve chamber 24. The pilot valve 1 has a pilot valve body with a first sealed cavity 17, a first channel, a second channel, and a second sealed cavity 112 arranged sequentially. Its pilot valve core slides within the pilot valve body and can open the first channel and close the second channel under the pressure difference between the medium entering the first sealed cavity 17 and the medium entering the second sealed cavity 112. The first control valve 3 can either close the first channel or open the second channel. The outlets of both the first and second channels are connected to the main sealing cavity 215. The first output port 315 of the first control valve 3 is connected to the first sealing cavity 17, its first input port 313 is connected to the primary loop volume control box or pressure relief box (atmospheric pressure P0), and its second input port 314 is connected to the constant pressure source injection tank (approximately 4-5 MPa). The second output port 415 of the second control valve 4 is connected to the inlet of the first channel and the second sealing cavity 112, respectively. Its third input port 413 is connected to the constant pressure source injection tank (approximately 4-5 MPa), and its fourth input port 414 is connected to the primary loop coolant (normally 15.5 MPa; in case of failure or refueling, it needs to be gradually depressurized to atmospheric pressure P0). The main valve's opening setpoint P... 0main Satisfy: P0 < P 0main <Pacc, the pilot valve opening setpoint P 0twin Satisfying: Pacc × A1 = P 0twin ×A2, therefore:

[0102] When this valve group is in standby mode (both the first control valve 3 and the second control valve 4 are de-energized), with the primary circuit pressure normal (approximately 15.5 MPa), the first sealing chamber 17 of the pilot valve 2 is at the constant pressure source injection tank pressure (approximately 4-5 MPa), and its second sealing chamber 112 is at the primary circuit pressure. The pilot valve core moves upward to open the first channel, thus the pressure source entering the main sealing chamber 215 of the main valve 2 is the primary circuit, which is much greater than the main valve 2 opening set value P. 0main When main valve 2 is closed, it isolates main valve 2 during normal operation of the primary circuit. In the event of a primary circuit fault, the pressure drop becomes less than the pressure setpoint P of pilot valve 1. 0twin When the pilot valve core moves down to open the second channel, the pressure source entering the main sealing chamber 215 of the main valve 2 is the primary circuit volume control box or pressure relief box (atmospheric pressure P0), which is less than the main valve 2 opening set value P. 0main The main valve 2 opens automatically, thus ensuring that when the primary circuit pressure is abnormal (P... rcs <P 0twinThe main valve 2 opens automatically without any energy input (because the first control valve 3 and the second control valve 4 are both de-energized, and the main valve 2 can open automatically when the primary circuit pressure meets the conditions).

[0103] In certain situations where the main valve 2 needs to be manually opened, the first solenoid valve 3 is de-energized and the second solenoid valve 4 is energized. At this time, the first sealing chamber 17 of the pilot valve 1 is at the pressure of the constant pressure source injection tank (approximately 4-5 MPa), and the second sealing chamber 112 is also at the pressure of the constant pressure source injection tank (approximately 4-5 MPa). The medium entering the second sealing chamber 112 opens the pressure setting value P of the pilot valve 1. 0twin The pressure is greater than the constant pressure source injection tank pressure Pacc, thus the pilot valve core is in a depressed state, the second channel opens, so the pressure source entering the main sealing cavity 215 of the main valve 2 is the primary circuit volume control box or pressure relief box (atmospheric pressure P0), which is less than the main valve 2 opening set value P. 0main Main valve 2 is open;

[0104] When shutting down the reactor for refueling (requiring the primary loop pressure to drop to atmospheric pressure) and not wanting the main valve 2 to open, first energize the first solenoid valve 3 and de-energize the second solenoid valve 4. At this time, the first sealing chamber 17 of the pilot valve 1 contains the primary loop volume control box or pressure relief box (atmospheric pressure P0), and the second sealing chamber 112 contains the primary loop pressure. When the primary loop pressure drops to the pressure setpoint P of the pilot valve 1... 0twin The following (while in standby mode, the pressure in the primary circuit drops to the pressure setpoint P of pilot valve 1) 0twin (Main valve 2 is already open), main valve 2 opening set value P 0main Previously, pilot valve 1 was in the upward position to open the first channel, and the pressure source entering the main sealing chamber 215 of main valve 2 was the primary loop. During this stage, main valve 2 was in the closed position, thus achieving high-pressure isolation of this valve group during the refueling shutdown. If the pressure in the primary loop continues to drop, main valve 2 will open, and thus the pressure in the primary loop will drop to the main valve 2 opening set value P. 0main Previously, both the first solenoid valve 3 and the second solenoid valve 4 were energized. At this time, the first sealing chamber 17 of the pilot valve 1 was at the pressure of the primary circuit volume control box or pressure relief box (atmospheric pressure P0), and the second sealing chamber 112 was at the pressure of the constant pressure source injection box. The pilot valve 1 was in the upward position to open the first channel. The pressure source entering the main sealing chamber 215 of the main valve 2 was the pressure of the constant pressure source injection box, which was greater than the opening setting value P of the main valve 2. 0main Even if the primary circuit pressure drops to the main valve 2 opening set value P, 0main Under these conditions, all main valves 2 are in the closed state, thereby achieving low-pressure isolation of this valve group during the shutdown and refueling period.

[0105] Furthermore, Table 1 shows a comparison of the advantages and disadvantages of the pressure relief valve assembly of the present invention with several overpressure protection valves and pressure relief valves commonly used in the field of nuclear power safety mentioned in the background art.

[0106] Table 1

[0107]

[0108] In this embodiment, the first control valve 3 includes a first control valve body 31, a first control piston assembly 32, and a first solenoid valve 33.

[0109] The first control valve body 31 has a first main chamber 311 and a first side chamber 312. The first control piston assembly 32 is disposed in the first main chamber 311, and the first solenoid valve 33 is disposed in the first side chamber 312. The first input port 313, the second input port 314, and the first output port 315 are all opened on the first control valve body 31 and are all connected to the first main chamber 311. The first control piston assembly 32 includes a first control piston rod 321 and a plurality of first control pistons 322 fixed on the first control piston rod 321. The plurality of first control pistons 322 are sequentially and slidably sealed in the first main chamber 311 along the axial direction of the first control piston rod 321 to divide the first main chamber 311 into a plurality of first sub-chambers. One end of the first control piston rod 321 extends out of the first main chamber 311 and is connected to the first solenoid valve 33.

[0110] The first output port 315 is located on one side of the first control piston rod 321 in the radial direction, and the first input port 313 and the second input port 314 are both located on the other side of the first control piston rod 321 in the radial direction. When the first solenoid valve 33 is energized, it can drive the first control piston assembly 32 to move axially to the first output port 315 through one of the first sub-cavities, which is connected only to the first input port 313. At the same time, the second input port 314 is located in the other adjacent first sub-cavity, so that the first control valve 3 is in the first energized state. When the first solenoid valve 33 is de-energized, it can drive the first control piston assembly 32 to move axially in the reverse direction to the first output port 315 through one of the first sub-cavities, which is connected only to the second input port 314. At the same time, the first input port 313 is located in the other adjacent first sub-cavity, so that the first control valve 3 is in the first de-energized state.

[0111] The second control valve 4 includes a second control valve body 41, a second control piston assembly 42, and a second solenoid valve 43.

[0112] The second control valve body 41 has a second main chamber 411 and a second side chamber 412. The second control piston assembly 42 is disposed in the second main chamber 411, and the second solenoid valve 43 is disposed in the second side chamber 412. The third input port 413, the fourth input port 414, and the second output port 415 are all opened on the second control valve body 41 and are all in communication with the second main chamber 411. The second control piston assembly 42 includes a second control piston rod 421 and a plurality of second control pistons 422 fixed on the second control piston rod 421. The plurality of second control pistons 422 are sequentially and slidably sealed in the second main chamber 411 along the axial direction of the second control piston rod 421 to divide the second main chamber 411 into a plurality of second sub-chambers. One end of the second control piston rod 421 extends out of the second main chamber 411 and is connected to the second solenoid valve 43.

[0113] The second output port 415 is located on one side of the second control piston rod 421 in the radial direction. The third input port 413 and the fourth input port 414 are both located on the other side of the second control piston rod 421 in the radial direction. When the second solenoid valve 43 is energized, it can drive the second control piston assembly 42 to move axially to the second output port 415, which communicates with the third input port 413 through one of the second sub-cavities. At the same time, the fourth input port 414 is located in the other adjacent second sub-cavity, so that the second control valve 4 is in the second energized state. When the second solenoid valve 43 is de-energized, the second control piston assembly 42 can move axially in the reverse direction to the second output port 415, which communicates with the fourth input port 414 through one of the second sub-cavities. At the same time, the third input port 413 is located in the other adjacent second sub-cavity, so that the second control valve 4 is in the second de-energized state.

[0114] In this embodiment,

[0115] The first solenoid valve 33 includes a first suction cup 331, a first coil 332, and a first return spring 333. The first coil 332 is fixed to the outer end wall of the first main chamber 311. The first suction cup 331 is fixed to one end of the first control piston rod 321 that extends into the first side chamber 312. The first return spring 333 is connected between the cavity wall of the first side chamber 312 and the first suction cup 331.

[0116] When the first solenoid valve 33 is energized, the first suction cup 331 moves toward the first coil 332 until it is fixed to it, so as to drive the first control piston assembly 32 to move axially to the first control valve 3 in the first energized state, and the first return spring 333 is stretched. When the first solenoid valve 33 is de-energized, the first suction cup 331 is disconnected from the first coil 332 and the first return spring 333 is reset, so as to drive the first control piston assembly 32 to move axially to the first control valve 3 in the first de-energized state.

[0117] The second solenoid valve 43 includes a second suction cup 431, a second coil 432, and a second return spring 433. The second coil 432 is fixed to the outer end wall of the second main chamber 411. The second suction cup 431 is fixed to one end of the second control piston rod 421 that extends into the second side chamber 412. The second return spring 433 is connected between the cavity wall of the second side chamber 412 and the second suction cup 431.

[0118] When the second solenoid valve 43 is energized, the second suction cup 431 moves toward the second coil 432 until it is fixed to it, so as to drive the second control piston assembly 42 to move axially to the second control valve 4 in the second energized state, and the second return spring 433 is stretched. When the second solenoid valve 43 is de-energized, the second suction cup 431 is disconnected from the second coil 432 and the second return spring 433 is reset, so as to drive the second control piston assembly 42 to move axially to the second control valve 4 in the second de-energized state.

[0119] In this embodiment, multiple sets of control valve assemblies are provided, and the first channel outlet and the second channel outlet of the multiple sets of control valve assemblies are both connected to the main sealing cavity 215 of the main valve 2.

[0120] Depending on the needs, a design can be adopted with one main valve 2 and two sets of parallel control valve assemblies to improve the overall reliability of the valve and prevent valve failure caused by the failure of a single component.

[0121] In this embodiment, the first control valve 3 has multiple first solenoid valves 33, and the first suction cups 331 of the multiple first solenoid valves 33 are all fixedly connected to the first control piston rod 321.

[0122] The second control valve 4 has multiple second solenoid valves 43, and the second suction cups 431 of the multiple second solenoid valves 43 are all fixedly connected to the second control piston rod 421.

[0123] Multiple solenoid valves can be installed in series on each control valve as needed to prevent control valve failure caused by a single solenoid valve failure or power supply failure.

[0124] In this embodiment, the main valve core includes a main piston assembly and a main spring 26. The main piston assembly includes a main piston rod, a main piston 25, and a valve disc 28. The main piston rod is slidably disposed in the main valve body. The main piston 25 is fixed on the main piston rod and located in the main sealing cavity 215. The valve disc 28 is fixed on the main piston rod and located in the main valve cavity 24. The main spring 26 is located in the main sealing cavity 215 and compressed between the main piston 25 and the bottom wall of the main valve cavity 24.

[0125] In this invention, the main valve 2 serves as the primary flow path for fluid during primary circuit depressurization. The valve's interior is subjected to high-temperature, high-pressure fluid. To avoid the impact of high-temperature fluid and vibration on the valve control and drive system, this invention employs a drive piston and drive spring as the energy source for opening and closing the main valve 2. The main valve 2 is connected to the pilot valve 1 via a pilot line to control the pressure within the sealing cavity 215, further controlling the opening and closing of the main valve 2.

[0126] In this embodiment,

[0127] The main valve chamber 24 is located below the main sealing chamber 215. The main valve body has a valve inlet 29 and a valve outlet 211 that communicate with the main valve chamber. The valve inlet 29 is located at the bottom of the main valve body and is used to connect with the primary coolant. The valve outlet 211 is located on the side of the main valve body and is used to connect with the atmosphere. The main piston assembly is vertically slidable within the main valve body.

[0128] The pressure set value P of the medium entering the main sealing cavity 215 opens the main valve 2. 0main Also satisfies: P 0main ×(A1-A2)+G=F, where A1 is the cross-sectional area of ​​the main piston 25, A2 is the cross-sectional area of ​​the valve disc 28, G is the weight of the main piston assembly, and F is the elastic force of the main spring when the main valve 2 is closed.

[0129] In the pressure relief valve assembly of the present invention, the opening, closing, and sealing of the main valve rely on the combined action of the drive spring, the pressure of the drive piston, and the system pressure, as detailed below:

[0130] The area of ​​the driving piston is larger than the area of ​​the valve disc. When the pressure of the sealing chamber × the area of ​​the driving piston + the weight of the piston assembly > the pressure of the driving spring + the pressure at the valve inlet × the area of ​​the valve disc, the valve is in the closed state and the valve is sealed by the pressure difference before and after the inequality.

[0131] When the pressure of the sealed chamber × the area of ​​the driving piston + the weight of the piston assembly < the pressure of the driving spring + the pressure at the valve inlet × the area of ​​the valve disc, the valve opens under the pressure of the driving spring and the internal pressure of the system, and the valve remains open by relying on the pressure of the driving spring.

[0132] In this embodiment,

[0133] The outer diameter of the valve disc 28 gradually decreases from top to bottom, so that the outer wall of the valve disc 28 forms a first conical surface.

[0134] A nozzle 210 is installed at the valve inlet 29. The upper part of the inner wall of the nozzle 210 has a second conical surface that mates with the first conical surface. When the main piston assembly moves down to mate with the first and second conical surfaces, the valve disc 28 closes the valve inlet 29.

[0135] The valve disc and nozzle have an inclined contact surface. When the valve is closed, the nozzle and valve disc can fit tightly under the action of pressure difference to better maintain the seal and prevent coolant leakage.

[0136] In this embodiment,

[0137] The main valve body comprises, from bottom to top, a main valve housing 21, a lower valve seat 22, and an upper valve seat 23, which are sequentially fixed together. The inner cavity of the main valve housing 21 forms the main valve chamber 24.

[0138] The top surface of the lower valve seat 22 has a first groove, the lower part of the upper valve seat 23 extends into the first groove and is sealed to the groove wall of the first groove, and the bottom surface of the upper valve seat 23 has a second groove, the groove wall of the second groove and the bottom wall of the first groove enclose to form the main sealing cavity 215.

[0139] In this embodiment, a pilot tube 214 is fixed inside the upper valve seat 23. One end of the pilot tube 214 extends into the main sealing cavity 215, and the other end extends out of the upper valve seat 23 and is connected to the first channel and the second channel of the pilot valve 1.

[0140] In this embodiment, the main piston rod includes a working section 27 and a positioning section 213. The lower end of the working section 27 is fixedly connected to the valve disc 28, and its upper end passes through the lower valve seat 22 and extends into the main sealing cavity 215 and is fixedly connected to the main piston 25. The main spring 26 passes through the working section 27.

[0141] The upper part of the upper valve seat 23 has a sealed exhaust chamber 212. The top of the upper valve seat 23 is provided with a valve cover 216 that opens or closes the exhaust chamber 212. The lower end of the positioning section 213 is fixed to the piston, and its upper end passes through the upper valve seat 23 and extends into the exhaust chamber 212.

[0142] In this embodiment,

[0143] The driving structure of the pilot valve 1 includes a first pilot piston 15, a second pilot piston 110, and a pilot piston rod 16. The pilot piston rod 16 is axially slidable within the pilot valve body and connected between the first pilot piston 15 and the second pilot piston 110. The first pilot piston 15 is slidably and sealingly disposed within a first sealing cavity 17, and the second pilot piston 110 is slidably and sealingly disposed within a second sealing cavity 112.

[0144] The valve core structure includes a first pilot valve, a second pilot valve, and a pilot valve stem 111. The pilot valve stem 111 is arranged parallel to and connected to the pilot piston rod 16. It is axially slidable in the pilot valve body and connected between the first pilot valve and the second pilot valve. The first pilot valve is located in the first channel and is used to open or close the first channel. The second pilot valve is located in the second channel and is used to open or close the second channel.

[0145] In this embodiment,

[0146] The first pilot valve includes a first valve plate 14 and a first valve core assembly 117. The first valve plate 14 is fixed in the first channel and closes the first channel, and has a first valve hole. The first valve core assembly 117 is slidably disposed in the first channel and cooperates with the first valve hole.

[0147] The second pilot valve includes a second valve plate 19 and a second valve core assembly 118. The second valve plate 19 is fixed in the second channel and closes the second channel, and has a second valve hole. The second valve core assembly 118 is slidably disposed in the second channel and cooperates with the second valve hole.

[0148] The pilot valve stem 111 is connected to the first valve core assembly 117 and the second valve core assembly 118. When it moves axially, it drives the first valve core assembly 117 to open the first valve hole and drives the second valve core assembly 118 to close the second valve hole, or drives the first valve core assembly 117 to close the first valve hole and drives the second valve core assembly 118 to open the second valve hole.

[0149] In this embodiment,

[0150] The first channel includes a first inlet section, a first pilot valve chamber 120, and a first outlet section connected in sequence. The first pilot valve is located within the first pilot valve chamber 120, which has space for the first valve core assembly 117 to slide.

[0151] The second channel includes a second inlet section, a second pilot valve chamber 121 and a second outlet section connected in sequence. The second outlet section is connected to the first outlet section. The second pilot valve is located in the second pilot valve chamber 121 and the second pilot valve chamber 121 has space for the second valve core assembly 118 to slide.

[0152] In this embodiment, both the first valve core assembly 117 and the second valve core assembly 118 include a valve core and a return spring. The return spring abuts against the cavity wall of the corresponding valve cavity.

[0153] During the process of the pilot valve stem 111 moving axially to drive the valve core to open the corresponding valve hole, the return spring is compressed. After the pressure source is removed, the return spring can push the corresponding valve core to close the corresponding valve hole during the reset process.

[0154] In this embodiment, a first input pipe 115 is provided in the first inlet section, a second input pipe 116 is provided in the second inlet section, and an output pipe 114 is provided in the first outlet section. The first input pipe 115, the second input pipe 116, and the output pipe 114 all extend out of the pilot valve body.

[0155] In this embodiment, the pilot piston rod 16 and the pilot valve rod 111 are connected by the pilot dial 119, and the pilot valve body is provided with a slot 122 that allows the pilot dial 119 to move axially along the pilot piston rod 16.

[0156] In this embodiment, the pilot valve body includes a first valve seat 11, an intermediate valve seat 13, and a second valve seat 12 that are sequentially fixed together.

[0157] The first sealing cavity 17 is located in the first valve seat 11, the second sealing cavity 112 is located in the second valve seat 12, and the first channel and the second channel are opened in the intermediate valve seat 13.

[0158] In this embodiment, the first valve seat 11 is sealed to the intermediate valve seat 13, and a third groove is formed on the end face of the first valve seat 11 facing the intermediate valve seat 13. The groove wall of the third groove and the end face of the intermediate valve seat 13 facing the first valve seat 11 together form a first sealing cavity 17.

[0159] The second valve seat 12 is sealed to the intermediate valve seat 13. A fourth groove is provided on the end face of the second valve seat 12 facing the intermediate valve seat 13. The groove wall of the fourth groove and the end face of the intermediate valve seat 13 facing the second valve seat 12 enclose each other to form a second sealing cavity 112.

[0160] In this embodiment, a first conduit 18 is fixed inside the first valve seat 11. One end of the first conduit 18 extends into the first sealing cavity 17, and the other end extends out of the first valve seat 11 for connection with the first output port 315.

[0161] A second conduit 113 is fixed inside the second valve seat 12. One end of the second conduit 113 extends into the second sealing cavity 112, and the other end extends out of the second valve seat 12 for connection with the second output port 415.

[0162] The pressure relief valve assembly of the present invention is used to achieve rapid pressure relief in the primary circuit, and its functions are as follows:

[0163] By controlling the opening and closing of the first control valve 3 and the second control valve 4, as well as the pressure levels of the pressure relief box, constant pressure source, and primary circuit, the pressure of the double piston pilot valve is controlled, ultimately controlling the opening and closing of the main valve of the pressure relief valve.

[0164] Assuming the primary loop pressure is Prcs, under normal operating conditions of a nuclear power plant, Prcs = 15.5 MPa. Under normal shutdown, refueling and overhaul conditions of a nuclear power plant, it can be gradually reduced to 0.1 MPa. The constant pressure source pressure is Pacc. For example, the pressure of the safety injection tank is usually about 4-5 MPa, and the pressure of the depressurization tank is P0, which is usually 0.1 MPa.

[0165] When the first solenoid valve 33 and the second solenoid valve 43 are energized and de-energized respectively, the pressure at various points of the pilot valve 1, the piston pressure of the main valve 2, and the functions performed by the main valve 2 are shown in Table 2.

[0166] Table 2

[0167]

[0168] Main valve function description:

[0169] Manual opening: In some cases in the nuclear power plant, the operator needs to manually open the pressure relief valve. At this time, the first solenoid valve 33 is de-energized, and the second solenoid valve 43 is energized, making the pressures of the first pilot piston and the second pilot piston equal, both equal to Pacc. Since the area of the first pilot piston is larger than that of the second pilot piston, the pilot valve stem moves downward, resulting in the main valve piston pressure = P0. At this time, the main valve opens under the action of the driving spring and the primary circuit pressure and can maintain the open state all the time.

[0170] Standby state: When the nuclear power plant is operating normally, the valve is in this state. At this time, both the first solenoid valve 33 and the second solenoid valve 43 are de-energized. The pressure of the first pilot piston = Pacc, and the pressure of the second pilot piston = Prcs. When Prcs > P 0twin (P 0twin is related to the area ratio of the first pilot piston to the second pilot piston. Here, it is assumed that the area ratio is 2:1, that is, P 0twin = 2 × Pacc, about 8 - 10 MPa), the pilot piston rod moves upward, resulting in the main piston pressure = Prcs. Since the area of the main valve piston is larger than the area of the valve disc, the main valve is in the closed state at this time. When Prcs < P 0twin (P 0twin is related to the area ratio of the first pilot piston to the second pilot piston. Here, it is assumed that the area ratio is 2:1, that is, P 0twin = 2 Pacc, about 8 - 10 MPa), the pilot piston rod moves downward, resulting in the main piston pressure = P0, and the main valve opens.

[0171] Isolation under high pressure: When the primary circuit is normally depressurized from 15.5 MPa and it is not desired for the pressure relief valve to open automatically, the pressure relief valve needs to be isolated. At this time, the first solenoid valve 33 is in the energized state, and the second solenoid valve 43 is in the de-energized state. The pressure of the first pilot piston = P0, and the pressure of the second pilot piston = Prcs. The pilot piston connecting rod moves upward, resulting in the main valve piston pressure = Prcs. Since the area of the main valve piston is larger than the area of the valve disc, when Prcs is greater than the main valve opening pressure P 0main the main valve remains in the closed state.

[0172] Isolation under low pressure: When the pressure of the primary circuit further decreases and Prcs is not sufficient to maintain the closed state of the main valve, it is necessary to switch to the low-pressure isolation state. At this time, both the first solenoid valve 33 and the second solenoid valve 43 are energized. The pressure of the first pilot piston = P0, and the pressure of the second pilot piston of the pilot valve = Pacc. Since Pacc is always constant at 4 - 5 MPa, the main valve can always be kept in the closed state when Prcs < Pacc.

[0173] Since P 0main<Pacc, so the switching between isolation under high pressure and isolation under low pressure can actually be determined according to the design of the main valve by selecting the pressure between P 0main- and Pacc. Generally, it can be selected around 3 MPa, slightly lower than the normal pressure of the constant pressure source accumulator tank.

[0174] While meeting the requirements of the primary circuit pressure relief of the subsequent models of Hualong, the pressure relief valve group is designed with the following technical advantages:

[0175] 1) In the standby state, when the pressure of the primary circuit meets the conditions, it automatically opens without any energy input, with high reliability.

[0176] 2) After the valve automatically opens, it can always maintain the open state and does not require any power supply to maintain the open state, ensuring long-term pressure relief of the primary circuit.

[0177] 3) Through different combinations of solenoid valves, the valve can be reliably isolated in any state, and can also be manually opened in any state.

[0178] 4) Through different combined configurations such as the parallel design of the pilot valve and the series design of the solenoid valve, redundant settings of the valve opening and isolation functions can be achieved, preventing valve failures caused by single component failures and improving the overall reliability of the valve.

[0179] 5) The leakage rate is low. During normal operation, the main valve piston is sealed by the pressure exerted by the primary circuit itself.

[0180] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present invention. However, the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A valve assembly for primary circuit pressure relief and discharge, characterized in that, include: The main valve (2) and control valve assembly, wherein the main valve (2) includes a main valve body and a main valve core, the main valve body having a main sealing cavity (215) and a main valve cavity (24), the main valve cavity (24) being used to connect the primary circuit coolant and the atmosphere, one end of the main valve core being located in the main sealing cavity (215) and the other end being located in the main valve cavity (24), the main valve core being able to slide within the main valve body under the pressure of the medium entering the main sealing cavity (215) to open or close the main valve cavity (24). The control valve assembly includes a pilot valve (1), a first control valve (3), and a second control valve (4). The pilot valve (1) includes a pilot valve body and a pilot valve core. The pilot valve body has a first sealing cavity (17), a first channel, a second channel, and a second sealing cavity (112) arranged sequentially. The pilot valve core includes a drive structure and a valve core structure. One end of the drive structure is located in the first sealing cavity (17), and the other end is located in the second sealing cavity (112). The valve core structure is connected to the drive structure, with one end located in the first channel and the other end located in the second channel. The drive structure can slide within the pilot valve body under the pressure difference between the medium entering the first sealing cavity (17) and the medium entering the second sealing cavity (112), thereby driving the valve core structure to open the first channel and close the second channel, or close the first channel and open the second channel. The outlets of the first channel and the second channel are both connected to the main sealing cavity (215). The first control valve (3) has a first input port (313), a second input port (314), and a first output port (315). The first output port (315) is connected to the first sealing cavity (17), the first input port (313) is connected to the primary circuit volume control box or the pressure relief box, and the second input port (314) is connected to the constant pressure source. The second control valve (4) has a third input port (413), a fourth input port (414), and a second output port (415). The second output port (415) is connected to the inlet of the first channel and the second sealing cavity (112) respectively. The third input port (413) is connected to the constant pressure source, and the fourth input port (414) is connected to the primary coolant. When the first control valve (3) is energized, its first output port (315) is connected to the first input port (313) and disconnected from the second input port (314). When the first control valve (3) is de-energized, its first output port (315) is connected to the second input port (314) and disconnected from the first input port (313). When the second control valve (4) is energized, its second output port (415) is connected to the third input port (413) and disconnected from the fourth input port (414). When the second control valve (4) is de-energized, its second output port (415) is connected to the fourth input port (414) and disconnected from the third input port (413). The pressure setting value P of the medium opening main valve (2) in the main sealing cavity (215) 0main Satisfies: P0 < P 0main < Pacc, wherein P0 is the atmospheric pressure, and Pacc is the pressure of the constant pressure source. The pressure setting value P of the pilot valve (1) is opened by the medium entering the second sealed cavity (112) 0twin satisfies: Pacc x A1 = P 0twin x A2, wherein Pacc is the pressure of the constant pressure source, A1 is the cross-sectional area of the first pilot piston (15), A2 is the cross-sectional area of the second pilot piston (110), and A2 < A1. The drive structure includes a first pilot piston (15), a second pilot piston (110), and a pilot piston rod (16). The pilot piston rod (16) is axially slidably disposed in the pilot valve body and connected between the first pilot piston (15) and the second pilot piston (110). The first pilot piston (15) is slidably disposed in the first sealing cavity (17), and the second pilot piston (110) is slidably disposed in the second sealing cavity (112).

2. The valve assembly for primary circuit pressure relief and discharge according to claim 1, characterized in that, The first control valve (3) includes a first control valve body (31), a first control piston assembly (32), and a first solenoid valve (33). The first control valve body (31) has a first main chamber (311) and a first side chamber (312). The first control piston assembly (32) is located in the first main chamber (311), and the first solenoid valve (33) is located in the first side chamber (312). The first input port (313), the second input port (314), and the first output port (315) are all located on the first control valve body (31) and are all connected to the first main chamber (311). The first control piston assembly (32) The device includes a first control piston rod (321) and multiple first control pistons (322) fixed on the first control piston rod (321). The multiple first control pistons (322) are sequentially and slidably disposed in the first main chamber (311) along the axial direction of the first control piston rod (321) to divide the first main chamber (311) into multiple first sub-chambers. One end of the first control piston rod (321) extends out of the first main chamber (311) and is connected to the first solenoid valve (33). The first output port (315) is located on one side of the first control piston rod (321) in the radial direction. The first input port (313) and the second input port (314) are both located on the other side of the first control piston rod (321) in the radial direction. When the first solenoid valve (33) is energized, it can drive the first control piston assembly (32) to move axially to the first output port (315) and communicate with the first input port (313) through one of the first sub-cavities. At the same time, the second input port (314) is located in the other adjacent first sub-cavity, so that the first control valve (3) is in the first energized state. When the first solenoid valve (33) is de-energized, it can drive the first control piston assembly (32) to move axially in the reverse direction to the first output port (315) and communicate with the second input port (314) through one of the first sub-cavities. At the same time, the first input port (313) is located in the other adjacent first sub-cavity, so that the first control valve (3) is in the first de-energized state. The second control valve (4) includes a second control valve body (41), a second control piston assembly (42), and a second solenoid valve (43). The second control valve body (41) has a second main chamber (411) and a second side chamber (412). The second control piston assembly (42) is located in the second main chamber (411), and the second solenoid valve (43) is located in the second side chamber (412). The third input port (413), the fourth input port (414), and the second output port (415) are all opened on the second control valve body (41) and are all connected to the second main chamber (411). The second control piston assembly (42) includes a second control piston rod (421) and a plurality of second control pistons (422) fixed on the second control piston rod (421). The plurality of second control pistons (422) are sequentially and sealed in the second main chamber (411) along the axial direction of the second control piston rod (421) to divide the second main chamber (411) into a plurality of second sub-chambers. One end of the second control piston rod (421) extends out of the second main chamber (411) and is connected to the second solenoid valve (43). The second output port (415) is located on one side of the radial direction of the second control piston rod (421), and the third input port (413) and the fourth input port (414) are both located on the other side of the radial direction of the second control piston rod (421). When the second solenoid valve (43) is energized, it can drive the second control piston assembly (42) to move axially to the second output port (415) and communicate with the third input port (413) through one of the second sub-cavities. At the same time, the fourth input port (414) is located in the other adjacent second sub-cavity, so that the second control valve (4) is in the second energized state. When the second solenoid valve (43) is de-energized, the second control piston assembly (42) can move axially in the reverse direction to the second output port (415) and communicate with the fourth input port (414) through one of the second sub-cavities. At the same time, the third input port (413) is located in the other adjacent second sub-cavity, so that the second control valve (4) is in the second de-energized state.

3. The valve assembly for primary circuit pressure relief and discharge according to claim 2, characterized in that, The first solenoid valve (33) includes a first suction cup (331), a first coil (332), and a first return spring (333). The first coil (332) is fixed to the outer end wall of the first main chamber (311). The first suction cup (331) is fixed to one end of the first control piston rod (321) that extends into the first side chamber (312). The first return spring (333) is connected between the cavity wall of the first side chamber (312) and the first suction cup (331). When the first solenoid valve (33) is energized, the first suction cup (331) moves toward the first coil (332) and is fixed thereto, so as to drive the first control piston assembly (32) to move axially to the first control valve (3) in the first energized state, and the first return spring (333) is stretched. When the first solenoid valve (33) is de-energized, the first suction cup (331) is disconnected from the first coil (332) and the first return spring (333) is reset, so as to drive the first control piston assembly (32) to move axially to the first control valve (3) in the first de-energized state. The second solenoid valve (43) includes a second suction cup (431), a second coil (432), and a second return spring (433). The second coil (432) is fixed to the outer end wall of the second main chamber (411). The second suction cup (431) is fixed to one end of the second control piston rod (421) that extends into the second side chamber (412). The second return spring (433) is connected between the cavity wall of the second side chamber (412) and the second suction cup (431). When the second solenoid valve (43) is energized, the second suction cup (431) moves toward the second coil (432) and is fixed thereto, so as to drive the second control piston assembly (42) to move axially to the second control valve (4) in the second energized state, and the second return spring (433) is stretched. When the second solenoid valve (43) is de-energized, the second suction cup (431) is disconnected from the second coil (432) and the second return spring (433) is reset, so as to drive the second control piston assembly (42) to move axially to the second control valve (4) in the second de-energized state.

4. The valve assembly for primary circuit pressure relief and discharge according to claim 1, characterized in that, The control valve assembly is provided in multiple sets, and the first channel outlet and the second channel outlet of the multiple sets of control valve assemblies are connected to the main sealing cavity (215) of the main valve (2).

5. The valve assembly for primary circuit pressure relief and discharge according to claim 3, characterized in that, The first control valve (3) has multiple first solenoid valves (33), and the first suction cups (331) of the multiple first solenoid valves (33) are all fixedly connected to the first control piston rod (321). The second control valve (4) has multiple second solenoid valves (43), and the second suction cups (431) of the multiple second solenoid valves (43) are all fixedly connected to the second control piston rod (421).

6. The valve assembly for primary circuit pressure relief and discharge according to any one of claims 1-5, characterized in that, The main valve core includes a main piston assembly and a main spring (26). The main piston assembly includes a main piston rod, a main piston (25), and a valve disc (28). The main piston rod is slidably disposed in the main valve body. The main piston (25) is fixed on the main piston rod and located in the main sealing cavity (215). The valve disc (28) is fixed on the main piston rod and located in the main valve cavity (24). The main spring (26) is located in the main sealing cavity (215) and compressed between the main piston (25) and the bottom wall of the main sealing cavity.

7. The valve assembly for primary circuit pressure relief and discharge according to claim 6, characterized in that, The main valve chamber (24) is located at the lower part of the main sealing chamber (215). The main valve body has a valve inlet (29) and a valve outlet (211) that are respectively connected to the main valve chamber. The valve inlet (29) is located at the bottom of the main valve body and is used to connect with the primary coolant. The valve outlet (211) is located on the side of the main valve body and is used to connect with the atmosphere. The main piston assembly is vertically slidable in the main valve body. The pressure set value P of the main valve (2) is opened by the medium entering the main sealing cavity (215). 0main Also satisfies: P 0main ×(A1-A2)+G=F, where A1 is the cross-sectional area of ​​the main piston (25), A2 is the cross-sectional area of ​​the valve disc (28), G is the weight of the main piston assembly, and F is the elastic force of the main spring when the main valve (2) is closed.

8. The valve assembly for primary circuit depressurization and discharge according to claim 7, characterized in that, The outer diameter of the valve disc (28) gradually decreases from top to bottom, so that the outer wall of the valve disc (28) forms a first conical surface. The valve inlet (29) is equipped with a nozzle (210), and the upper part of the inner wall of the nozzle (210) has a second conical surface that mates with the first conical surface. When the main piston assembly moves down to mate with the first and second conical surfaces, the valve disc (28) closes the valve inlet (29).

9. The valve assembly for primary circuit depressurization and discharge according to claim 6, characterized in that, The main valve body comprises, from bottom to top, a main valve housing (21), a lower valve seat (22), and an upper valve seat (23) that are fixedly connected in sequence, and the inner cavity of the main valve housing (21) forms the main valve cavity (24). The lower valve seat (22) has a first groove on its top surface. The lower part of the upper valve seat (23) extends into the first groove and is sealed to the groove wall of the first groove. The upper valve seat (23) has a second groove on its bottom surface. The groove wall of the second groove and the bottom wall of the first groove enclose the main sealing cavity (215).

10. The valve assembly for primary circuit depressurization and discharge according to claim 9, characterized in that, The main piston rod includes a working section (27) and a positioning section (213). The lower end of the working section (27) is fixedly connected to the valve disc (28), and its upper end passes through the lower valve seat (22) and extends into the main sealing cavity (215) and is fixedly connected to the main piston (25). The main spring (26) passes through the working section (27). The upper part of the upper valve seat (23) has a sealed exhaust chamber (212), and the top of the upper valve seat (23) is provided with a valve cover (216) for opening or sealing the exhaust chamber (212). The lower end of the positioning section (213) is fixedly connected to the main piston, and its upper end passes through the upper valve seat (23) and extends into the exhaust chamber (212).

11. The valve assembly for primary circuit pressure relief and discharge according to any one of claims 1-5, characterized in that, The valve core structure includes a first pilot valve, a second pilot valve, and a pilot valve stem (111). The pilot valve stem (111) is arranged parallel to and connected to the pilot piston rod (16). It is axially slidable in the pilot valve body and connected between the first pilot valve and the second pilot valve. The first pilot valve is located in the first channel and is used to open or close the first channel. The second pilot valve is located in the second channel and is used to open or close the second channel.

12. The valve assembly for primary circuit depressurization and discharge according to claim 11, characterized in that, The first pilot valve includes a first valve plate (14) and a first valve core assembly (117). The first valve plate (14) is fixed in the first channel and closes the first channel. A first valve hole is provided on the first valve plate. The first valve core assembly (117) is slidably disposed in the first channel and cooperates with the first valve hole. The second pilot valve includes a second valve plate (19) and a second valve core assembly (118). The second valve plate (19) is fixed in the second channel and closes the second channel. A second valve hole is provided on the second valve plate. The second valve core assembly (118) is slidably disposed in the second channel and cooperates with the second valve hole. The pilot valve stem (111) is connected to the first valve core assembly (117) and the second valve core assembly (118). When it moves axially, it drives the first valve core assembly (117) to open the first valve hole and drives the second valve core assembly (118) to close the second valve hole, or drives the first valve core assembly (117) to close the first valve hole and drives the second valve core assembly (118) to open the second valve hole.

13. The valve assembly for primary circuit depressurization and discharge according to claim 12, characterized in that, The first channel includes a first inlet section, a first pilot valve chamber (120), and a first outlet section connected in sequence. The first pilot valve is located in the first pilot valve chamber (120), and the first pilot valve chamber (120) has space for the first valve core assembly (117) to slide. The second channel includes a second inlet section, a second pilot valve chamber (121) and a second outlet section connected in sequence. The second outlet section is connected to the first outlet section. The second pilot valve is located in the second pilot valve chamber (121). The second pilot valve chamber (121) has space for the second valve core assembly (118) to slide.

14. The valve assembly for primary circuit depressurization and discharge according to claim 11, characterized in that, The pilot piston rod (16) is connected to the pilot valve rod (111) via a pilot dial (119), and the pilot valve body is provided with a slot (122) that allows the pilot dial (119) to move axially along the pilot piston rod (16).

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