Containment passive heat transfer system and containment passive residual heat transfer method
By designing a non-active thermal conductivity system for the containment for nuclear power units, the problem of how to ensure continuous heat discharge and pressure control in the containment during accident conditions is solved, and the automatic operation of the system and the inherent safety improvement of the system are achieved.
Patent Information
- Application Number
- CN202411881622.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-19
- Publication Date
- 2025-04-08
AI Technical Summary
During the accident operation, how to ensure continuous heat discharge from the containment, reduce the pressure in the containment and keep it within the design range, and prevent the accident from accelerating.
A non-active thermal conduction system for containment is designed, including a heat exchanger-condenser, a first containment isolation valve, a safety valve, a steam release device, an emergency heat discharge box and a second containment isolation valve. Under design benchmark accidents and design extension conditions, the heat from the containment shell is exported to the emergency heat discharge box through a heat exchanger-condenser, achieving continuous heat discharge and pressure control.
It realizes the operation and pressure control of the non-active thermal conductivity system of the containment during the design benchmark accident and the design extension conditions, ensures that the system is automatically put into operation during the accident, improves the inherent safety of the unit, and complies with the principles of independence and redundancy.
Smart Images
Figure CN119786092A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the field of nuclear power plant operation and automatic control technology, and specifically relates to a passive heat transfer system for a containment and a method for transferring passive residual heat from a containment. Background Art
[0002] During the operation of the reactor unit of a pressurized water reactor nuclear power plant, the primary coolant carries the heat energy released by the nuclear fuel out of the reactor and enters the steam generator. Through thousands of heat transfer tubes, the heat is transferred to the secondary water outside the tubes, causing the water to boil and produce steam. After the primary coolant flows through the steam generator, it is sent into the reactor by the main pump. This back and forth cycle continuously carries out the heat in the reactor and converts it into steam.
[0003] To improve the inherent safety of the reactor, the passive system is a major feature of the third-generation pressurized water reactor. However, how to ensure continuous heat removal from the containment during accident conditions, reduce the pressure in the containment and keep it within the design range, release the heat in the containment to the final heat sink, and prevent the accident from expanding. Summary of the invention
[0004] In view of this, the present application is committed to providing a passive heat transfer system for a containment and a method for passive residual heat extraction from a containment. By adding a passive heat transfer system for a containment to a nuclear power unit, the heat of the containment is extracted to an emergency heat extraction box through a heat exchanger-condenser, so as to solve the existing problem of how to ensure continuous heat extraction from the containment during accident conditions, reduce the pressure in the containment and maintain it within the design range, release the heat in the containment to the final heat sink, and prevent the accident from expanding.
[0005] In a first aspect, the present application provides a passive heat transfer system for a containment of a nuclear power unit, which includes a heat exchanger-condenser, a first containment isolation valve, a safety valve, a steam release device, an emergency heat removal box, and a second containment isolation valve. The steam release device is located in the emergency heat removal box and is submerged in the water of the emergency heat removal box. The first containment isolation valve is connected in series between the heat exchanger-condenser and the steam release device, and the second containment isolation valve is connected in series between the heat exchanger-condenser and the steam release device located between the emergency heat removal box. The safety valve is connected in parallel with the first containment isolation valve. The heat exchanger-condenser is used to be arranged at a first preset position around the inner wall of the containment. The emergency heat removal box is used to be arranged at a second preset position of the external structure of the containment. The first containment isolation valve and the second containment isolation valve are in an open state, and the safety valve is in a closed state. The safety valve is used to protect the system components in the containment from overpressure in the case of emergency closure of the first containment isolation valve and / or the second containment isolation valve. The safety valve is used to be installed in the fluid supply pipeline leading to the emergency heat removal box. Under the design basis accident and design expansion conditions, the heat of the containment is exchanged to the heat exchanger-condenser, and the heat of the heat exchanger-condenser passes through the riser where the first containment isolation valve is located and then released to the emergency heat removal box through the steam release device.
[0006] In a specific embodiment of the present application, the passive heat transfer system of the containment further comprises an electric isolation valve. An electric isolation valve is provided on each row of pipelines of the passive heat transfer system of the containment that runs through the containment, and the electric isolation valve is designed to isolate the fault circuit when the integrity of the equipment and pipelines of the passive heat transfer system of the containment is lost.
[0007] In a specific implementation of the present application, the first preset position is an elevation of +49.300 m.
[0008] In a specific implementation of the present application, the second preset position is an elevation of +59.850 m.
[0009] In a specific embodiment of the present application, the design basis accident is a loss of coolant accident in the containment. The design extension conditions include all design extension conditions related to the containment mass and energy generation, as well as the design extension conditions in which core melting occurs.
[0010] The second aspect of the present application provides a method for passively exporting residual heat from the containment of a nuclear power unit, and the method for passively exporting residual heat from the containment of a nuclear power unit comprises: during operation of the equipment under normal operating conditions and expected operating events, the passive heat transfer system of the containment of the first aspect of the present application is in a standby state, the heat exchanger-condenser is in a standby state, the first containment isolation valve and the second containment isolation valve are opened, the safety valve is closed, the steam release device is in a standby state, and the emergency heat removal box is at a normal liquid level; under design basis accidents and design expansion conditions, when any pressure and temperature in the containment rise to a threshold value, the passive heat transfer system of the containment provided in an embodiment of the present application starts to operate, natural circulation begins to be established, the heat of the containment is exchanged to the heat exchanger-condenser, and the heat of the heat exchanger-condenser passes through the riser where the first containment isolation valve is located and then is released to the emergency heat removal box through the steam release device.
[0011] In a specific embodiment of the present application, the method for extracting passive residual heat from the containment further includes: after 24 hours, using mobile equipment and on-site water reserves, the passive heat transfer system of the containment continues to operate normally to achieve continuous heat removal from the containment.
[0012] The beneficial effect of the technical solution of the present application is that: by setting the passive heat transfer system of the containment including a heat exchanger-condenser, a first containment isolation valve, a safety valve, a steam release device, an emergency heat removal box and a second containment isolation valve, under the design basis accident and design expansion conditions, the heat of the containment is exchanged to the heat exchanger-condenser, and the heat of the heat exchanger-condenser passes through the riser where the first containment isolation valve is located and then released to the emergency heat removal box through the steam release device, thereby realizing that the passive heat transfer system of the containment will be put into operation and control the pressure in the containment during the design basis accident and design expansion conditions. There is no relevant instrumentation and control logic when the system is put into operation. When the pressure and temperature in the containment rise to a certain value (for example, 30°C to 50°C), a natural circulation will be established and the unit will be automatically put into operation, thereby improving the inherent safety of the unit. The design of the passive heat removal system of the containment provided in the embodiment of the present application complies with the principles of independence and redundancy; the required functions are performed in consideration of single failure principles or human errors. BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Figure 1 Shown is a schematic structural diagram of a passive heat conduction system for a containment vessel provided in one embodiment of the present application. DETAILED DESCRIPTION
[0014] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0015] At least one embodiment of the present application provides a passive heat transfer system for a containment of a nuclear power unit, which includes a heat exchanger-condenser 1, a first containment isolation valve 2, a safety valve 3, a steam release device 4, an emergency heat removal box 5, and a second containment isolation valve 6. The steam release device 4 is located in the emergency heat removal box 5 and is submerged in the water of the emergency heat removal box 5. The first containment isolation valve 2 is connected in series between the heat exchanger-condenser 1 and the steam release device 4, and the second containment isolation valve 6 is connected in series between the heat exchanger-condenser 1 and the steam release device 4 located between the emergency heat removal box 5. The safety valve 3 is connected in parallel with the first containment isolation valve 2. The heat exchanger-condenser 1 is used to be arranged at a first preset position around the inner wall of the containment. The emergency heat removal box 5 is used to be arranged at a second preset position of the external structure of the containment. The first containment isolation valve 2 and the second containment isolation valve 6 are in an open state, and the safety valve 3 is in a closed state. The safety valve 3 is used to protect the system components in the containment from overpressure in the case of emergency closure of the first containment isolation valve 2 and / or the second containment isolation valve 6. The safety valve 3 is used to be installed in the fluid supply pipeline leading to the emergency heat removal box 5. Under the design basis accident and design expansion conditions, the heat of the containment is exchanged to the heat exchanger-condenser 1, and the heat of the heat exchanger-condenser 1 is released to the emergency heat removal box 5 through the steam release device 4 after passing through the riser where the first containment isolation valve 2 is located.
[0016] It should be noted that the emergency heat removal box 5 is the final heat sink. The passive heat transfer system of the containment can be referred to as the JMP system. The passive heat transfer system of the containment can also be referred to as the passive heat removal system of the containment. For example, the nuclear power unit can be a VVER1000 unit or a VVER1200 unit.
[0017] Design basis accident: During a loss of coolant in the containment, the passive start principle of the system creates conditions for the JMP system to operate under any pressure and temperature increase in the containment.
[0018] Design Extended Conditions: The JMP system is used to maintain the pressure in the containment below the design value without operator assistance for at least 24 hours under all design extended conditions related to containment mass and energy production. After 24 hours, the system operation should be ensured using mobile equipment available on site and spare plant water (supplementing the emergency heat removal tank).
[0019] According to the technical solution provided in the embodiment of the present application, the passive heat transfer system for the containment of the nuclear power unit includes a heat exchanger-condenser 1, a first containment isolation valve 2, a safety valve 3, a steam release device 4, an emergency heat removal box 5 and a second containment isolation valve 6. Under the design basis accident and design expansion conditions, the heat of the containment is exchanged to the heat exchanger-condenser 1, and the heat of the heat exchanger-condenser 1 passes through the riser where the first containment isolation valve 2 is located and then released to the emergency heat removal box 5 through the steam release device 4, thereby realizing that the passive heat transfer system of the containment will be put into operation and control the pressure in the containment during the design basis accident and design expansion conditions. There is no relevant instrumentation and control logic when the system is put into operation. When the pressure and temperature in the containment rise to a certain value (for example, 30°C to 50°C), a natural circulation will be established and the unit will be automatically put into operation, thereby improving the inherent safety of the unit. The design of the passive heat removal system of the containment provided in the embodiment of the present application complies with the principles of independence and redundancy; it performs the required functions in consideration of the single fault principle or human error, and can operate based on the passive principle during the accident.
[0020] In at least one embodiment of the present application, the passive heat transfer system for the containment of a nuclear power unit further comprises an electric isolation valve. An electric isolation valve is provided on each row of pipelines of the passive heat transfer system for the containment that runs through the containment, and the electric isolation valve is designed to isolate the fault circuit when the integrity of the equipment and pipelines of the passive heat transfer system for the containment is lost.
[0021] In at least one embodiment of the present application, the first preset position is an elevation of +49.300 m.
[0022] In at least one embodiment of the present application, the second preset position is an elevation of +59.850 m.
[0023] In at least one embodiment of the present application, the design basis accident is a loss of coolant accident in the containment. The design extension conditions include all design extension conditions related to the mass and energy generation of the containment, as well as design extension conditions in which core melting occurs. Thus, under the design basis accident of a loss of coolant accident in the containment, the passive heat transfer system of the containment will start to operate passively under any pressure and temperature increase in the containment; under all design extension conditions related to the mass and energy generation of the containment, the passive heat transfer system of the containment will be able to maintain the pressure in the containment at a level lower than the design value without the assistance of the operator for at least 24 hours, release the heat in the containment to the final heat sink, and control the pressure of the containment within the design range when the design extension condition of core melting occurs, to prevent the spillage of radioactive materials into the environment.
[0024] At least one embodiment of the present application further provides a method for removing passive residual heat from a containment vessel of a nuclear power plant. The method for removing passive residual heat from a containment vessel of a nuclear power plant comprises the following steps.
[0025] S1: During the operation of the equipment under normal operating conditions and expected operating events, the passive heat transfer system of the containment provided in the embodiment of the present application is in a standby state, the heat exchanger-condenser 1 is in a standby state, the first containment isolation valve 2 and the second containment isolation valve 6 are opened, the safety valve 3 is closed, the steam release device 4 is in a standby state, and the emergency heat exhaust box 5 is at a normal liquid level.
[0026] It should be noted that normal operating conditions are also the conditions corresponding to normal reactor power operation. In the standby state, the room where the system components are located should maintain the environmental parameters required for the normal operation of the equipment. When the system is operated under the design expansion conditions, the ventilation requirements do not apply.
[0027] In some embodiments, during operation of the equipment under normal operating conditions and expected operating events, the availability of the passive thermal transfer system of the containment is ensured by monitoring component status, using an emergency heat removal box to meet water level requirements in the box, and maintaining the required temperature in the storage box.
[0028] S2: Under design basis accidents and design expansion conditions, when any pressure and temperature in the containment rise to a threshold value, the passive heat transfer system of the containment provided in the embodiment of the present application starts to operate, natural circulation begins to be established, and the heat of the containment is exchanged to the heat exchanger-condenser 1. The heat of the heat exchanger-condenser 1 passes through the riser where the first containment isolation valve 2 is located and then is released to the emergency heat exhaust box 5 through the steam release device 4.
[0029] According to the technical solution provided in the embodiment of the present application, under the design basis accident and design expansion conditions, the heat of the containment is exported to the emergency heat dissipation box 5 through the heat exchanger-condenser 1, thereby ensuring continuous heat dissipation from the containment, reducing the pressure in the containment and maintaining it within the design range, and releasing the heat in the containment to the emergency heat dissipation box 5 to prevent the accident from expanding.
[0030] In at least one embodiment of the present application, the method for removing passive residual heat from the containment of a nuclear power unit further includes S3.
[0031] S3: After 24 hours, the passive heat transfer system of the containment continued to operate normally using mobile equipment and on-site water reserves to achieve continuous heat removal from the containment.
[0032] It should be noted that the on-site water reserve can be the use of cooling water to supplement the emergency heat removal tank.
[0033] In some embodiments, within 24 hours before the occurrence of an accident, the system thermal power is sufficient to maintain the pressure in the containment within the design limits under the design extended operating conditions, and the system will perform the required functions without the need for automated control measures, operator intervention and power supply.
[0034] It should be noted that the combination of the various technical features in the embodiments of the present application is not limited to the combination described in the embodiments of the present application or the combination described in the specific embodiments, and all technical features described in the present application can be freely combined or combined in any way unless there is a contradiction between them.
[0035] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an" and / or "the" do not refer to the singular and may also include the plural. Generally speaking, the term "comprising" only indicates that the steps and elements that have been clearly identified are included, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements.
[0036] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features.
[0037] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. A passive heat transfer system for a containment of a nuclear power unit, characterized in that: Heat exchanger-condenser, first containment isolation valve, safety valve, steam release device, emergency heat removal box and second containment isolation valve, The steam release device is located in the emergency heat removal box and is submerged in the water of the emergency heat removal box; the first containment isolation valve is connected in series between the heat exchanger-condenser and the steam release device, the second containment isolation valve is connected in series between the heat exchanger-condenser and the steam release device located between the emergency heat removal box, and the safety valve is connected in parallel with the first containment isolation valve; The heat exchanger-condenser is arranged at a first preset position along the inner wall of the containment, the emergency heat removal box is arranged at a second preset position of the external structure of the containment, the first containment isolation valve and the second containment isolation valve are in an open state, and the safety valve is in a closed state. The safety valve is used to protect the system components located in the containment from overpressure in the case of emergency closure of the first containment isolation valve and / or the second containment isolation valve. The safety valve is used to be installed in a fluid supply pipeline leading to the emergency heat removal box; Under design basis accidents and design expansion conditions, the heat of the containment is exchanged to the heat exchanger-condenser. The heat of the heat exchanger-condenser passes through the riser where the first containment isolation valve is located and then released to the emergency heat exhaust box through the steam release device.
2. A passive heat transfer system for a containment of a nuclear power plant according to claim 1, characterized in that: Also includes electric isolation valves, Among them, an electric isolation valve is installed on each row of pipelines of the containment passive heat transfer system that runs through the containment. The electric isolation valve is designed to isolate the fault circuit when the integrity of the equipment and pipelines of the containment passive heat transfer system is lost.
3. The passive heat transfer system for containment of a nuclear power plant according to claim 1, characterized in that: The first preset position is at an elevation of +49.300m.
4. The passive heat transfer system for containment of a nuclear power plant according to claim 1, characterized in that: The second preset position is at an elevation of +59.850m.
5. A passive heat transfer system for a containment of a nuclear power plant according to any one of claims 1 to 4, characterized in that: The design basis accident is a loss of coolant in the containment. The design extension conditions include all design extension conditions related to the containment mass and energy generation, as well as the design extension conditions of core melting.
6. A method for removing passive residual heat from a containment of a nuclear power unit, characterized in that: During the operation of the equipment under normal operating conditions and expected operating events, the passive heat transfer system of the containment for a nuclear power unit according to any one of claims 1 to 5 is in a standby state, the heat exchanger-condenser is in a standby state, the first containment isolation valve and the second containment isolation valve are open, the safety valve is closed, the steam release device is in a standby state, and the emergency heat removal tank is at a normal liquid level; Under design basis accidents and design expansion conditions, when any pressure and temperature in the containment rise to a threshold value, the passive heat transfer system of the containment provided in the embodiment of the present application starts to operate, natural circulation begins to be established, and the heat of the containment is exchanged to the heat exchanger-condenser. The heat of the heat exchanger-condenser passes through the riser where the first containment isolation valve is located and then is released to the emergency heat exhaust box through the steam release device.
7. The method according to claim 6, characterized in that Also includes: After 24 hours, the passive heat transfer system of the containment continued to operate normally using mobile equipment and on-site water reserves, achieving continuous heat removal from the containment.