Filtering and discharging system for containment of nuclear power plant

Abstract

The invention provides a nuclear power plant containment filtering and discharging system, and relates to the technical field of nuclear power plant safe discharging. A nuclear power plant containment filtering and discharging system comprises a venturi water scrubber communicated with a containment; the metal fiber filter is connected with the Venturi water scrubber in series, and the outlet end of the metal fiber filter is communicated with a chimney; the liquid storage tank is connected with the Venturi water scrubber through a first pipeline, and a metering pump is arranged on the first pipeline; and the water replenishing unit is communicated with the liquid storage tank so as to add water into the liquid storage tank, and the chemical agent injected into the liquid storage tank is prepared into chemical liquid capable of being replenished into the Venturi water scrubber. The technical problem that an existing filtering and discharging system is not provided with a fixed medicine adding and liquid supplementing device is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power plant safety emissions, and in particular to a containment filtration and emission system for a nuclear power plant. Background Art

[0002] Nuclear power plant designs must practically eliminate the possibility of plant operating conditions that could lead to early or large-scale radioactive releases. Following a severe reactor accident, a core melt would cause a large amount of steam and non-condensable gases to accumulate within the containment vessel, posing a serious threat to its integrity. Therefore, it is necessary to actively discharge these gases through pressure relief to ensure containment integrity, keeping the pressure within the containment below its rated capacity. Furthermore, to prevent unacceptable radioactive hazards to the environment and the public, it is necessary to install filtration devices on the pressure relief pipelines to filter and retain radioactive materials in the discharge gases. This ensures that any radioactive materials inevitably released into the environment are kept to the lowest possible level, ensuring environmental friendliness and public dose safety. Selecting a high-efficiency containment filtration and discharge system is of practical significance in eliminating the risk of containment overpressure and preventing uncontrolled radioactive releases. At present, most newly built and operating pressurized water reactor nuclear power plants at home and abroad have installed containment filtration and discharge systems after severe accidents to ensure the integrity of the containment, thereby preventing large-scale release of radioactive materials due to overpressure in the containment. Currently, the largest-scale application in engineering is the wet filtration and discharge solution (i.e., a combined filtration unit of off-shell Venturi water washing filtration and metal fiber filtration).

[0003] For wet filtration, a passive pressurized water reactor nuclear power plant filtration, discharge and retention device with water washing and retention and mechanical filtration functions is mainly provided. In its water washing and retention unit, a certain concentration of chemical liquid needs to be stored to ensure the effective retention of radioactive nuclides, but the existing filtration and discharge system does not have a special dosing and rehydration device. Summary of the Invention

[0004] In view of the above shortcomings of the prior art, the present invention provides a nuclear power plant containment filtration and drainage system to improve the technical problem that the existing filtration and drainage system does not have a fixed dosing and liquid replenishing device.

[0005] To achieve the above-mentioned objectives and other related objectives, the present invention provides a nuclear power plant containment filtration and emission system, comprising: a Venturi scrubber, which is connected to the containment; a metal fiber filter, which is connected in series with the Venturi scrubber, and the outlet end of the metal fiber filter is connected to the chimney; a liquid storage tank, which is connected to the Venturi scrubber via a first pipe, and a metering pump is provided on the first pipe; a water replenishment unit, which is connected to the liquid storage tank to add water to the liquid storage tank, and configures the chemical agents added to the liquid storage tank to be a chemical liquid that can be replenished into the Venturi scrubber.

[0006] In an exemplary embodiment of the present application, a stirring device is provided on the liquid storage tank, and the stirring device extends into the liquid storage tank.

[0007] In an exemplary embodiment of the present application, a nitrogen supply portion is included, and the nitrogen supply portion is connected to the liquid storage tank through a second pipe.

[0008] In an exemplary embodiment of the present application, a first nitrogen replenishment check valve and a first nitrogen replenishment isolation valve are provided on the second pipeline.

[0009] In an exemplary embodiment of the present application, the nitrogen supply unit is connected to the Venturi scrubber via a third pipe.

[0010] In an exemplary embodiment of the present application, a second nitrogen replenishment check valve and a second nitrogen replenishment isolation valve are provided on the third pipeline.

[0011] In an exemplary embodiment of the present application, a return pipe is provided on the first pipe, and the return pipe is connected to the liquid storage tank through the first pipe.

[0012] In an exemplary embodiment of the present application, the first pipe is connected to the lower part of the liquid storage tank, and the return pipe is connected to the upper part of the liquid storage tank.

[0013] In an exemplary embodiment of the present application, the return pipe is connected downstream of the fluid infusion metering pump.

[0014] In an exemplary embodiment of the present application, a dosing system is further included, and the dosing system is connected to the liquid storage tank to add chemicals into the liquid storage tank.

[0015] In an exemplary embodiment of the present application, the water replenishment unit is a passive water replenishment unit, the water replenishment unit is connected to the liquid storage tank via a fourth pipe, and a water replenishment isolation valve is provided on the fourth pipe.

[0016] In an exemplary embodiment of the present application, a fluid replenishment isolation valve and a fluid replenishment check valve are provided on the first pipeline, and the fluid replenishment isolation valve is a seismic-resistant electric valve.

[0017] In an exemplary embodiment of the present application, a fifth pipe is included, which connects the liquid storage tank and the Venturi scrubber, and a backflow isolation valve is provided on the fifth pipe; wherein the height of the liquid storage tank is lower than the height of the Venturi scrubber.

[0018] In combination with the prior art, the beneficial effects of the present invention are:

[0019] The existing filtering and discharging device does not have a fixed rehydration device, and the risk of rehydration is relatively high. This application adds a liquid storage tank and a water replenishment unit to the filtering and discharging system. When the chemical liquid in the venturi scrubber fails or is insufficient, the chemical liquid is replenished to the venturi scrubber in time through the liquid storage tank to ensure the filterability of the filtering and discharging system. Compared with the existing non-kinetic rehydration, the first pipeline of this application is provided with a metering pump, which can improve the efficiency of rehydration in the venturi scrubber and ensure that the venturi scrubber can be replenished in time after a serious accident. It reduces the difficulty of rehydration in the filtering and discharging device, avoids the risk of flooding, and simplifies the process system configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 This is a schematic diagram of an exemplary filtering and draining device of the present application;

[0022] Component number description

[0023] 100. Venturi scrubber;

[0024] 200, Metal fiber filter;

[0025] 300, liquid storage tank; 310, stirring device; 320, sampling branch pipe; 321, sampling isolation valve; 330, purge branch pipe; 331, purge isolation valve; 340, liquid level gauge; 350, second protection safety valve;

[0026] 400, water supply unit; 410, water supply isolation valve;

[0027] 500, first pipeline; 510, metering pump; 520, fluid replenishment isolation valve; 530, fluid replenishment check valve; 540, second isolation valve;

[0028] 600, nitrogen supply unit; 610, first nitrogen replenishment check valve; 620, first nitrogen replenishment isolation valve; 630, second nitrogen replenishment check valve; 640, second nitrogen replenishment isolation valve;

[0029] 700, reflux pipe; 710, fluid replenishment protection safety valve;

[0030] 800, sewage branch pipe; 810, sewage isolation valve;

[0031] 900, fifth pipeline; 910, backflow isolation valve. DETAILED DESCRIPTION

[0032] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following examples and the features in the examples can be combined with each other unless they conflict. It should also be understood that the terms used in the examples of the present invention are for the purpose of describing specific embodiments, not for the purpose of limiting the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0033] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those described in the examples of the present invention may also be used to implement the present invention.

[0034] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0035] Nuclear power plants must practically eliminate the possibility of operating conditions that could lead to early or large-scale radioactive releases. Therefore, in exceptional circumstances, active pressure relief is necessary to discharge these gases outside the containment vessel, ensuring the containment's integrity by maintaining the pressure within the containment vessel below its rated capacity. Furthermore, to prevent unacceptable radiological hazards to the environment and the public, filtration devices must be installed on the pressure relief pipeline to filter and retain radioactive materials in the discharged gases. This ensures that any radioactive materials released into the environment are kept to the lowest possible level, ensuring environmental friendliness and public dose safety. Newly built and operating pressurized water reactor (PWR) nuclear power plants have implemented post-severe accident containment filtration and drainage systems to ensure containment integrity and prevent large-scale radioactive releases caused by containment overpressure. The most widely used wet filtration and drainage solution in this application is a combination of an external Venturi water-washing filter and a metal fiber filter. The Venturi water-washing filter contains a chemical solution with a specific concentration to effectively retain the radionuclides. The existing water-washing filter does not have a special liquid replenishing device, which makes it difficult to mix and replace the liquid in the Venturi water-washing filter.

[0036] In view of this, the present application provides a nuclear power plant containment filtration and emission system to facilitate the proportioning, replacement, and replenishment of the liquid medicine in the venturi scrubber 100, thereby improving the safety and stability of the filtration and emission system. The filtration and emission system includes a venturi scrubber 100, a metal fiber filter 200, a liquid storage tank 300, and a water replenishment unit 400. The venturi scrubber 100 is connected to the containment, and the venturi scrubber 100 utilizes the venturi effect to mix and separate gas and liquid, mainly removing radioactive substances in the exhaust gas, such as aerosols, iodine, and methyl iodide. The metal fiber filter 200 is connected in series with the venturi scrubber 100, and the metal fiber filter 200 is connected in series downstream of the venturi scrubber 100 to remove tiny particles and residual substances that are difficult to be captured by the venturi scrubber 100. Furthermore, a separation water circuit is provided at the bottom of the metal fiber filter 200, and the separation water circuit is connected to the venturi scrubber 100 so that the liquid separated in the metal fiber filter 200 flows back into the venturi scrubber 100. The outlet end of the metal fiber filter 200 is connected to the chimney, and the gas filtered by the metal fiber filter 200 flows out of the metal fiber filter 200 through the outlet end of the metal fiber filter 200 and is discharged through the pipe and the chimney. Other filtering or gas treatment structures can also be provided between the metal fiber filter 200 and the chimney. Please refer to the existing filtering and exhaust system, which will not be described in detail in this application. The liquid storage tank 300 is connected to the venturi scrubber 100 through a first pipe 500, and a metering pump 510 is provided on the first pipe 500. By providing a fixed liquid storage tank 300, the venturi scrubber 100 can be easily replenished. The water replenishment unit 400 is connected to the liquid storage tank 300 to add water to the liquid storage tank 300. The chemical agent added to the liquid storage tank 300 is configured to be replenished into the chemical liquid of the venturi scrubber 100. The present application uses active liquid replenishment to replenish the chemical liquid in the liquid storage tank 300 into the venturi scrubber 100, effectively supporting the ability of the venturi scrubber 100 to retain radioactive nuclides and improving the safety of the filtration and discharge process.

[0037] In another embodiment, a first conduit 500 is connected to the lower portion of the venturi scrubber 100, allowing the chemical liquid in the venturi scrubber 100 to flow into the liquid storage tank 300 via the first conduit 500. This facilitates temporary storage of effective chemical liquid during inspection and maintenance of the venturi scrubber 100, thereby improving the convenience of inspection and maintenance of the filtration and exhaust system. In one embodiment, a pump connected in parallel with the metering pump 510 is provided on the first conduit 500, allowing the chemical liquid in the venturi scrubber 100 to flow into the liquid storage tank 300.

[0038] In one embodiment of the present application, the filtration and discharge system further includes a dosing system, which is connected to the liquid storage tank 300 to add chemicals into the liquid storage tank 300. The dosing system can dynamically adjust the amount of chemical added to the liquid storage tank 300, thereby preparing a chemical liquid of a suitable proportion to meet the need for replenishing the chemical liquid in the Venturi scrubber 100.

[0039] In one embodiment of the present application, the liquid storage tank 300 is provided with a stirring device 310, which extends into the liquid storage tank 300. After a certain proportion of chemical agents are mixed in the liquid storage tank 300, the stirring device 310 can quickly achieve chemical addition and stirring, thereby ensuring rapid fluid replenishment. Furthermore, the stirring device 310 is controlled by a stirring controller. After a certain proportion of chemical agents are added to the liquid storage tank 300, the stirring device 310 is activated, and subsequent chemical addition and stirring are performed simultaneously, thereby improving stirring efficiency, improving the efficiency of chemical solution preparation, and ensuring rapid fluid replenishment.

[0040] In one embodiment of the present application, a return pipe 700 is provided on the first pipe 500, and the return pipe 700 is connected to the liquid storage tank 300 by the first pipe 500. A liquid replenishment protection safety valve 710 is provided on the return pipe 700 to protect the metering pump 510 under special circumstances. The return pipe 700 allows the liquid in the first pipe 500 to flow back into the liquid storage tank 300.

[0041] In one embodiment of the present application, the reflux pipe 700 is connected downstream of the fluid infusion metering pump 510, the first pipe 500 is connected to the lower part of the liquid storage tank 300, and the reflux pipe 700 is connected to the upper part of the liquid storage tank 300, so that the reflux pipe 700 can return the liquid to the liquid storage tank 300.

[0042] In one embodiment of the present application, a nitrogen supply unit 600 is included. The nitrogen supply unit 600 is connected to the liquid storage tank 300 via a second pipe. The second pipe is provided with a first nitrogen replenishment check valve 610 and a first nitrogen replenishment isolation valve 620. When the filtration and discharge system is operating normally, in order to ensure timely and rapid rehydration, chemicals or prepared chemical liquids are contained in the liquid storage tank 300. Preferably, chemicals are contained in the liquid storage tank 300 for easy storage. The nitrogen supply unit 600 is connected to the liquid storage tank 300, and nitrogen is filled into the liquid storage tank 300 through the nitrogen supply unit 600 to cover the chemicals or chemical liquids, thereby facilitating the storage of the chemicals or chemical liquids.

[0043] In one embodiment of the present application, the nitrogen supply part 600 is connected to the venturi scrubber 100 through a third pipe. The third pipe is provided with a second nitrogen replenishment check valve and a second nitrogen replenishment isolation valve 640 to inject nitrogen into the venturi scrubber 100 through the nitrogen supply part 600.

[0044] In one embodiment of the present application, the water replenishment unit 400 is a passive water replenishment unit 400, and the water replenishment unit 400 is connected to the liquid storage tank 300 through a fourth pipe. A water replenishment isolation valve 410 is provided on the fourth pipe to facilitate the replenishment of water into the liquid storage tank 300 to facilitate the preparation of chemical liquid.

[0045] In one embodiment of the present application, a fluid replenishment isolation valve 520 and a fluid replenishment check valve 530 are provided on the first pipeline 500. The fluid replenishment isolation valve 520 is a shock-resistant electric valve. The shock-resistant electric valve ensures that the fluid replenishment isolation valve 520 can be used after vibration and other situations, thereby ensuring stable fluid replenishment of the filtration and discharge system.

[0046] In one embodiment, a second isolation valve 540 is provided on the first pipeline 500. The second isolation valve 540 is provided upstream of the metering pump 510 to control the connection and disconnection between the liquid storage tank 300 and the metering pump 510. Furthermore, the second isolation valve 540 is a two-way isolation valve.

[0047] In one embodiment, a drainage branch pipe 800 is provided on the first pipeline 500, and a drainage isolation valve 810 is provided on the drainage branch pipe 800. The drainage branch pipe 800 is located downstream of the metering pump 510 and upstream of the liquid replenishment isolation valve 520. When cleaning the liquid storage tank 300, liquid or gas flows out through the drainage branch pipe 800. Furthermore, a purge branch pipe 330 is provided on the liquid storage tank 300, and a purge isolation valve 331 is provided on the purge branch pipe 330 to facilitate the injection of gas into the liquid storage tank 300 through the purge branch pipe 330 to remove impurities, moisture, or other unwanted substances remaining in the liquid storage tank 300 and related pipelines.

[0048] In one embodiment, a sampling branch pipe 320 is provided at the bottom of the liquid storage tank 300 , and a sampling isolation valve 321 is provided on the sampling branch pipe 320 to facilitate sampling or discharging the liquid in the liquid storage tank 300 , thereby detecting the liquid in the liquid storage tank 300 .

[0049] In one embodiment, a liquid level gauge 340 is provided on the liquid storage tank 300 for detecting the liquid level in the liquid storage tank 300 , and a liquid level measurement root valve is provided at the front of the liquid level gauge 340 .

[0050] In one embodiment, the liquid storage tank 300 is further provided with a second protective safety valve 350 to provide pressure relief protection when the pressure in the liquid storage tank 300 is too high, thereby improving the safety of the liquid storage tank 300 .

[0051] For example, the volume of the liquid storage tank 300 needs to be determined according to the actual needs of a specific project.

[0052] In an exemplary embodiment of the present application, a nuclear power plant containment filtration and drainage system includes a fifth conduit 900 connecting the liquid storage tank 300 and the venturi scrubber 100. A backflow isolation valve 910 is provided on the fifth conduit 900. The height of the liquid storage tank 300 is lower than that of the venturi scrubber 100. The provision of the fifth conduit 900 enables reverse communication between the liquid storage tank 300 and the venturi scrubber 100. Specifically, chemical liquid in the venturi scrubber 100 flows back into the liquid storage tank 300, facilitating temporary storage of chemical liquid in the liquid storage tank 300 during inspection of the venturi scrubber 100. The lower height of the liquid storage tank 300 allows chemical liquid to flow passively from the venturi scrubber 100 to the liquid storage tank 300, reducing pumping requirements and costs.

[0053] In one embodiment, the connection between the fifth pipe 900 and the venturi scrubber 100 is located below the venturi scrubber 100 to facilitate the flow of chemical liquid out of the venturi scrubber 100. Furthermore, the fifth pipe 900 shares the connection between the first pipe 500 and the venturi scrubber 100, thereby reducing the number of connection ports on the venturi scrubber 100 and facilitating the processing of the venturi scrubber 100.

[0054] In one embodiment, the connection between the fifth pipe 900 and the liquid storage tank 300 is located in the middle or upper portion of the liquid storage tank 300, thereby reducing resistance to the flow of chemical liquid into the liquid storage tank 300 and increasing the speed at which the chemical liquid flows back from the venturi scrubber 100 to the liquid storage tank 300. The present invention provides a nuclear power plant containment filtration and drainage system capable of actively replenishing liquid into the venturi scrubber 100, resolving the problem of existing filtration and drainage systems lacking a fixed dosing and replenishing device. Furthermore, the liquid storage tank 300 can be used to temporarily store chemical liquid during inspection of the venturi scrubber 100.

[0055] Therefore, the present invention effectively overcomes some practical problems in the prior art and thus has high utilization value and practical significance. The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A nuclear power plant containment filtration and exhaust system, characterized in that: include: a venturi scrubber, connected to the containment vessel; a metal fiber filter connected in series with the Venturi scrubber, wherein the outlet end of the metal fiber filter is in communication with the chimney; a liquid storage tank, the liquid storage tank being connected to the venturi scrubber via a first pipe, the first pipe being connected to the lower portion of the venturi scrubber, and the first pipe being provided with a metering pump; The water replenishing unit is connected to the liquid storage tank to add water into the liquid storage tank, and the chemical agent added into the liquid storage tank is configured to be a chemical liquid that can be replenished into the venturi water scrubber.

2. The nuclear power plant containment filtration and exhaust system according to claim 1, characterized in that: The liquid storage tank is provided with a stirring device, and the stirring device extends into the liquid storage tank.

3. The nuclear power plant containment filtration and exhaust system according to claim 1, characterized in that: A nitrogen supply unit is included, and the nitrogen supply unit is connected to the liquid storage tank through a second pipeline.

4. The nuclear power plant containment filtration and exhaust system according to claim 3, characterized in that: The second pipeline is provided with a first nitrogen replenishment check valve and a first nitrogen replenishment isolation valve.

5. The nuclear power plant containment filtration and exhaust system according to claim 3, characterized in that: The nitrogen supply unit is connected to the Venturi scrubber through a third pipe.

6. The nuclear power plant containment filtration and exhaust system according to claim 5, characterized in that: The third pipeline is provided with a second nitrogen replenishment check valve and a second nitrogen replenishment isolation valve.

7. The nuclear power plant containment filtration and exhaust system according to claim 1, characterized in that: A return pipe is provided on the first pipe, and the return pipe is connected to the liquid storage tank through the first pipe.

8. The nuclear power plant containment filtration and exhaust system according to claim 7, characterized in that: The first pipe is connected to the lower part of the liquid storage tank, and the return pipe is connected to the upper part of the liquid storage tank.

9. The nuclear power plant containment filtration and exhaust system according to claim 7, characterized in that: The return pipe is connected to the downstream of the metering pump.

10. The nuclear power plant containment filtration and exhaust system according to claim 1, characterized in that: The device also includes a drug adding system, which is connected to the liquid storage tank to add chemical agents into the liquid storage tank.

11. The nuclear power plant containment filtration and exhaust system according to claim 1, characterized in that: The water replenishment unit is a passive water replenishment unit, and the water replenishment unit is connected to the liquid storage tank through a fourth pipe, and a water replenishment isolation valve is provided on the fourth pipe.

12. The nuclear power plant containment filtration and exhaust system according to claim 1, characterized in that: The first pipeline is provided with a fluid replenishment isolation valve and a fluid replenishment check valve, and the fluid replenishment isolation valve is a seismic-resistant electric valve.

13. The nuclear power plant containment filtration and exhaust system according to claim 1, characterized in that: include: a fifth pipeline connecting the liquid storage tank and the Venturi scrubber, wherein the fifth pipeline is provided with a backflow isolation valve; Wherein, the height of the liquid storage tank is lower than the height of the Venturi scrubber.

Images