CN119833176A - Containment pressure-restraining filtering discharge system and method and application thereof - Google Patents
Containment pressure-restraining filtering discharge system and method and application thereof Download PDFInfo
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- CN119833176A CN119833176A CN202411719326.XA CN202411719326A CN119833176A CN 119833176 A CN119833176 A CN 119833176A CN 202411719326 A CN202411719326 A CN 202411719326A CN 119833176 A CN119833176 A CN 119833176A
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Abstract
The invention relates to a containment pressure-restraining filtering discharge system and method and application thereof, belonging to the field of special safety facilities and radiation protection of nuclear power devices. The containment pressure-restraining filtering and discharging system comprises a discharging valve (2), a discharging pipeline (3), a spray pipe (4), a pressure-restraining water tank, a capacity expansion chamber (7), a steam-water separator (9), a metal fiber filter layer (10), a rupture disk (12), a heat exchanger and a valve. The containment pressure-suppressing filtering and discharging system is characterized in that a seawater side heat exchanger and a pressure-suppressing pool heat exchanger are arranged, a natural circulation loop is constructed by means of the potential difference between the seawater side heat exchanger and the pressure-suppressing pool heat exchanger and the temperature difference between the seawater and the liquid phase in the pressure-suppressing pool under accident conditions, the non-time-limit export of the heat of the pressure-suppressing pool under LOCA accidents or main steam pipeline cracking accident conditions in the containment is realized, the rapid pressure suppression of the containment and the efficient retention of airborne radioactive substances can be realized by adopting a multistage bubbling pressure-suppressing water washing method, and the occupation of total resources is reduced by arranging a combined metal fiber filter layer.
Description
Technical Field
The invention belongs to the field of special safety facilities and radiation protection of nuclear power devices, and particularly relates to a containment pressure-restraining filtering discharge system and method and application thereof.
Background
The containment vessel is used as a cabin for loading high-energy and high-radioactivity equipment such as a reactor, a loop system and the like and pipelines in an offshore nuclear power platform, and is the last safety barrier for preventing radioactive substances from being released to the external environment after a break accident occurs, so that the integrity of the containment vessel is of great significance. For marine nuclear power plants, floating power plants, etc., the free volume of the containment vessel is much smaller than that of the containment vessel of a nuclear power plant due to the constraints of overall resources. When a circuit in the containment is broken, a large amount of high-temperature and high-pressure coolant is sprayed into the containment by flash evaporation, so that the pressure in the containment is rapidly increased, and if the pressure cannot be rapidly reduced, the pressure in the containment is rapidly increased within tens of seconds and exceeds the design pressure. The existing third-generation nuclear power Hualong No. I is provided with a containment spraying system and an passive containment heat export system to meet the heat rejection requirement of the containment under the condition of break accidents. However, the extremely high mass energy release rate at the initial stage of a containment breach accident can not meet the requirement of containment depressurization only by means of a spraying system and a passive containment cooling system. The improved boiling water reactor (ABWR) nuclear power plant in Japan and the Russian marine nuclear power plant KLT-40S are provided with a pressure suppression pool, high-temperature and high-pressure gas in a dry well is rapidly discharged into a wet well under accident conditions, and liquid in the wet well is directly contacted with steam to be condensed, so that the rapid cooling and depressurization of the containment vessel are realized. In addition, when the system is actually operated, radioactive substances carried in the exhaust gas are greatly retained in the liquid phase under the action of various removing mechanisms, so that the containment pressure suppression system also plays a role in washing and removing the radioactive substances.
The problem of containment over-pressurization late in a severe accident is also of concern. The existing nuclear power station is provided with a containment filtering and discharging system, namely, the pressure in the containment is not more than the bearing limit value of the containment through an active pressure relief method, so that the integrity of the containment is ensured, and meanwhile, radioactive substances in discharged gas are filtered through a filtering device arranged on a pressure relief pipeline to prevent radioactive products from leaking. The main current containment filtration and discharge system mainly comprises two stages of wet venturi washing and dry metal fiber filtration. But the filter of this type has larger volume and supporting facilities and occupies more total resources.
When LOCA accident (Loss of Coolant Accident ) occurs in the primary circuit in the containment, if the containment spraying system and the passive containment heat-conducting system fail after the suppression system is put into operation, the temperature of the liquid phase in the suppression pool will gradually rise until reaching the saturation temperature, and the suppression performance of the suppression system is basically failed at this time. The water washing efficiency of the airborne radioactive substance is obviously reduced along with the rise of the liquid phase temperature, and simultaneously, along with the evaporation of the liquid phase, the aerosol particles which are originally remained in the liquid phase are carried into the gas phase again by the gas phase, so that the water washing efficiency of the radioactive substance is seriously affected.
Therefore, aiming at the problems of rapid pressure relief of the containment vessel and removal of radioactive substances when a break accident occurs in the floating nuclear power platform, the system needs to be designed and optimized by comprehensively considering factors in various aspects.
Disclosure of Invention
In order to meet the requirements of rapid depressurization of a containment vessel and efficient removal of radioactive substances after an accident of a floating nuclear power platform and solve the problems of system pressure inhibition performance and reduction of air-borne radioactive substance washing efficiency caused by liquid phase temperature increase in a pressure inhibition pool under the condition of long-term heat release of serious accidents, the invention provides a containment vessel pressure inhibition and filtration emission system and method and application thereof.
In order to achieve the above object, the present invention adopts the following technical scheme.
In a first aspect, the invention provides a containment pressure-suppressing filtering and discharging system, which comprises a discharging valve, a discharging pipeline, a spray pipe, a pressure-suppressing water tank, a capacity-expanding chamber, a steam-water separator, a metal fiber filter layer, a rupture disk, a heat exchanger and a valve, wherein
A containment vessel in communication with the suppression pool via the discharge conduit, an interface location of the discharge conduit with the containment vessel being located at an upper portion of the containment vessel, the discharge valve being disposed at a top portion of the discharge conduit and being located outside of the containment vessel (e.g., immediately outside of the containment vessel);
the spray pipe is arranged at the tail end of the discharge pipeline and is positioned at the bottom of the pressure suppression pool;
the expansion chamber is arranged at one side of the pressure-restraining water tank, and the expansion chamber is communicated with the pressure-restraining water tank through a pipeline;
The steam-water separator and the metal fiber filter layer are arranged at the upper part of the interior of the expansion chamber, and the steam-water separator and the metal fiber filter layer are adjacently arranged;
the rupture disk is positioned on a filter discharge pipeline connected with the metal fiber filter layer;
the heat exchanger comprises a pressure restraining water tank heat exchanger and a seawater side heat exchanger.
After LOCA accident occurs in the containment, when the pressure in the containment reaches the opening pressure of the discharge valve connected with the containment, the discharge valve is automatically opened, the steam-air mixture (namely, the discharge gas) in the containment is bubbled into the pressure-suppressing pool through the spray pipe, and the bubbling is directly contacted with the solution in the pressure-suppressing pool (also called as coolant due to low solution temperature) to perform efficient heat exchange (wherein part of the discharge gas is condensed), so that the rapid depressurization of the containment can be realized, and the pressure peak value of the containment in the initial stage of the accident can be reduced.
As an alternative embodiment, the nozzle is mounted vertically downwards.
In the invention, the spray pipe in the pressure-restraining water tank adopts a vertical downward installation mode to increase the submerged depth of the spray nozzle, which is beneficial to heat exchange of gas and liquid phases and bubbling water washing of radioactive substances.
As an alternative embodiment, the repressurization pool comprises a plurality of sub-repressurization pools.
As an alternative implementation mode, the repression water tank comprises a first-stage repression water tank and a second-stage repression water tank, and communicating pipes are arranged at the bottoms of the first-stage repression water tank and the second-stage repression water tank.
As an alternative embodiment, the interior of the repression tank is loaded with a mixed solution of sodium hydroxide and sodium thiosulfate.
The invention adopts multistage bubbling heat exchange and water washing, and can efficiently remove radioactive substances in the exhaust gas, including aerosol and iodine. Specifically, the mixed solution of sodium hydroxide and sodium thiosulfate loaded in the pressure-restraining water tank can absorb iodine in the exhaust gas through chemical reaction. Taking the two-stage bubbling heat exchange and water washing as an example, in the first-stage bubbling water washing (which occurs in a first-stage pressure-inhibiting water tank), the gas at the outlet of the spray pipe is in a high-speed jet state, and the liquid phase is entrained into the gas plume to form a large number of entrained liquid drops. The aerosol is captured and removed by the entrained droplets through capture mechanisms such as inertial collision, interception and the like, and the radioactive iodine is absorbed by the entrained droplets. Meanwhile, the steam share of the exhaust gas is higher, and the steam condensation can also obviously improve the removal efficiency of the aerosol. As the energy of the exhaust gas dissipates, the gas flow pattern is changed from jet flow to bubble group. The radioactive substance diffuses and migrates to the surface of the bubble in the bubble and is retained by the liquid phase. After the bubbling condensation of the first stage, the effluent gas is mainly left as non-condensable gas. In the second-stage bubbling water washing, the flow rate of the exhaust gas at the outlet of the spray pipe is reduced, the size of bubbles is reduced, the specific surface area is increased, the residence time of the bubbles in the liquid phase is increased, and the removal efficiency of the radioactive substance is increased.
The invention adopts two-stage or multi-stage bubbling water washing, which is equivalent to increasing the submerged depth of the pressure-inhibiting spray pipe, so that the detention time of gas in the liquid phase is obviously increased, and the removal efficiency of the gas-borne radioactive substances can be effectively improved.
As an alternative embodiment, the suppression pool heat exchanger is disposed inside the first stage suppression pool.
As an alternative embodiment, the seawater side heat exchanger is located in the seawater and the seawater side heat exchanger is located higher than the height of the hold-down pool heat exchanger.
As an alternative implementation manner, the top pipeline of the repression water tank heat exchanger is connected with the top pipeline of the seawater side heat exchanger, and the bottom pipeline of the repression water tank heat exchanger is connected with the bottom pipeline of the seawater side heat exchanger, so that a natural circulation loop is constructed.
As an alternative embodiment, the tube side of the heat exchanger is filled with desalinated water.
According to the invention, by means of the height difference (or level difference) between the sea water liquid level and the pressure-restraining pond and the temperature difference between the sea water and the liquid phase in the pressure-restraining pond under accident conditions, and arranging the heat exchangers with the tube sides filled with desalted water on the pressure-restraining pond and the sea water side respectively, a natural circulation loop is constructed, so that the non-time-limit export of the heat of the pressure-restraining pond under the accident conditions can be realized, and the pressure-restraining performance of the containment pressure-restraining filtering discharge system and the removal efficiency of airborne radioactive substances are improved.
According to the invention, on the premise of ensuring the pressure-restraining function of the pressure-restraining water tank and the source water washing efficiency, the water loading of the pressure-restraining water tank is reduced by the capacity-expanding means, so that the weight of the system is reduced.
As an alternative embodiment, the steam-water separator is arranged at a relative position of a pipeline communicating the expansion chamber and the metal fiber filter layer.
As an alternative embodiment, the steam-water separator is a folded-plate steam-water separator.
In the invention, the steam-water separator is used for dehumidifying the exhaust gas.
As an alternative embodiment, a discharge valve is provided upstream of the steam-water separator.
As an alternative embodiment, the opening pressure of the discharge valve is less than the design bearing of the containment vessel and the suppression pool.
As an alternative embodiment, a rupture disc is arranged downstream of the metal fiber filter layer.
As an alternative embodiment, the burst disk has the same opening pressure as the discharge valve 8.
According to the invention, the discharge valve is arranged at the upstream of the metal fiber filter layer, the rupture membrane is arranged at the downstream of the metal fiber filter layer, the opening pressure of the discharge valve is properly smaller than the design bearing pressure of the containment vessel and the pressure-restraining water tank, the opening pressure of the rupture membrane is the same as the opening pressure of the discharge valve, and when the pressure of the pressure-restraining water tank and the expansion chamber reaches the opening pressure of the discharge valve, the discharge valve and the rupture membrane are sequentially opened, so that the filtration discharge of the high-temperature and high-pressure gas in the containment vessel and the pressure-restraining water tank is realized.
As an alternative embodiment, the metal fiber filter layer is a combined metal fiber filter layer.
According to the invention, the combined metal fiber filter is arranged by means of the existing structural space, so that the capture of the aerosol with the particle size which is most easily penetrated and is difficult to remove by bubbling water washing is realized, the radioactivity of the discharged gas is further reduced, and the occupation of the total resources can be reduced.
As an alternative embodiment, the combined metal fiber filter layer is provided with a plurality of metal fiber layers which are stacked in a combination mode with different mesh numbers and different wire diameters.
The combined metal fiber filter layer can realize high-efficiency capture of small-particle-size aerosol.
As an alternative embodiment, a parallel pipeline is arranged on the pipeline where the rupture disc is located, and a valve is arranged on the parallel pipeline, wherein the valve can be opened electrically and remotely or manually (i.e. opened manually in situ).
In the invention, the pipeline where the rupture disk is positioned is provided with the parallel pipeline, and when the rupture disk fails to open, a valve on the parallel pipeline can be opened electrically and remotely or manually in situ.
As an alternative implementation manner, a valve is further arranged in the containment, and is used for respectively communicating or isolating the containment and the pressure-restraining water tank or/and the expansion chamber.
In the invention, when the pressure in the pressure-restraining water tank and the expansion chamber is obviously higher than the pressure of the containment vessel, a valve connected between the pressure-restraining water tank and the containment vessel and a valve connected between the expansion chamber and the containment vessel are opened to release the pressure of the pressure-restraining water tank and the expansion chamber, and when the pressure of the containment vessel is higher than the pressure of the pressure-restraining water tank again, the pressure-restraining water tank continuously realizes the functions of heat sink and water washing.
As an optional implementation manner, the containment pressure-suppressing filter discharge system further comprises a filter discharge pipeline (or a filter discharge pipeline), and a flow-limiting pore plate is arranged at the downstream of the filter discharge pipeline and used for controlling the flow of the filtered discharge gas, so that the filtration efficiency of the airborne radioactive substances is improved as much as possible on the premise of ensuring the pressure-suppressing effect.
In the invention, the filtering and discharging pipeline is used for communicating the steam-water separator with the metal fiber filter layer and discharging the dehumidified and filtered discharged gas.
As an alternative embodiment, a radioactivity monitor is provided downstream of the filtered discharge line, which can be used to monitor the amount of radioactivity released into the environment, as well as the filtration capacity of the system for airborne radioactive substances.
The containment pressure-restraining filtering discharge system provided by the invention has an passive cooling function, is suitable for a floating nuclear power platform, and is used for rapid pressure reduction of the containment after an accident of the floating nuclear power platform and efficient removal of radioactive substances.
In a second aspect, the present invention provides a containment pressure-suppressing, filtering and discharging method, using the containment pressure-suppressing, filtering and discharging system, the containment pressure-suppressing, filtering and discharging method comprising the steps of:
1) When LOCA accident occurs in the containment, after the pressure in the containment reaches the opening pressure of the discharge valve, the discharge valve is automatically opened based on the pressure difference, and the discharge gas from the high-temperature high-pressure steam-air mixture in the containment is bubbled into a pressure-restraining water tank through a spray pipe to perform bubbling heat exchange (equivalent to the pressure-restraining water tank having a heat sink function) and water washing, so that the containment 1 is depressurized, and meanwhile, radioactive substances in the steam-air mixture are removed;
Constructing a natural circulation loop by means of a height difference between the liquid level of the seawater and the first-stage pressure-suppressing pond and a temperature difference between the seawater and the liquid phase in the first-stage pressure-suppressing pond under accident conditions and a heat exchanger filled with desalted water on the pipe sides of the first-stage pressure-suppressing pond and the seawater side;
2) When the pressure of the pressure-restraining water tank or the expansion chamber is higher than the pressure of the containment vessel, a valve connecting the pressure-restraining water tank and the containment vessel or/and a valve connecting the expansion chamber and the containment vessel are opened to release the pressure of the pressure-restraining water tank or/and the expansion chamber, and when the pressure of the containment vessel is higher than the pressure of the pressure-restraining water tank again, the flow of the step 1) is carried out again, so that the pressure-restraining water tank can continuously realize the functions of hot-trap and water washing;
3) The exhaust gas subjected to multistage bubbling heat exchange and water washing enters a capacity expansion chamber, and the containment pressure is further reduced by a pressure inhibition and capacity expansion method;
4) When the pressure of the containment or the pressure-restraining pool reaches the design pressure of filtration and discharge, a valve on a filtration and discharge pipeline is opened, and the filtered and discharged gas passes through a steam-water separator and then flows through a metal fiber filter layer for filtration (aerosol in the discharged gas is removed), and the filtered discharged gas passes through a rupture disk or a valve;
5) The exhaust gas passing through the rupture disk or valve is released into the environment through the orifice plate while the radioactive material released into the environment is monitored.
As an alternative embodiment, the step 1) further includes the steps of:
By utilizing the height difference between the seawater and the repressing water tank and the temperature difference between the seawater and the liquid phase in the repressing water tank under the serious accident condition, a natural circulation loop is constructed through the repressing water tank heat exchanger and the seawater side heat exchanger, the non-time-limit export of the heat in the containment vessel and the repressing water tank is realized, and the water washing detention efficiency of the airborne radioactive substances is improved.
As an alternative embodiment, in the step 1), the pressure-suppressing water tank further includes a multi-stage sub-pressure-suppressing water tank, and the radioactive substances in the exhaust gas are removed by multi-stage bubbling water washing.
Optionally, the pressure suppression pool comprises a first-stage pressure suppression pool and a second-stage pressure suppression pool, and the radioactive substances in the exhaust gas are removed by two-stage bubbling water washing.
In a third aspect, the invention provides an application of the containment pressure-suppressing filter discharge system in a floating nuclear power platform.
In the invention, the containment pressure-restraining filtering discharge system has an passive cooling function, is suitable for a floating nuclear power platform, and is used for depressurization of the containment and removal of radioactive substances after an accident of the floating nuclear power platform.
In the invention, the technical characteristics can be freely combined to form a new technical scheme under the condition of no conflict.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
(1) The containment pressure-restraining filtering discharge system provided by the invention adopts a multistage bubbling pressure-restraining water washing method, so that water resources in a pressure-restraining water tank can be fully utilized, and the rapid pressure restraint of the containment and the high-efficiency retention of airborne radioactive substances can be realized under the condition of limited resources;
(2) The containment pressure-restraining filtering and discharging system provided by the invention utilizes the structural space of the containment pressure-restraining filtering and discharging system in the prior art, and can reduce the occupation of total resources by arranging the combined metal fiber filter layers;
(3) Compared with a containment filtration and discharge system of a nuclear power mainstream, the containment pressure-restraining filtration and discharge system provided by the invention can ensure higher radioactive substance removal efficiency, simultaneously reduces Venturi water washing links, avoids the trouble that the filtration and discharge device needs to be periodically replenished with liquid, has a simple and feasible scheme, occupies less total resources and has good economy;
(4) According to the containment pressure-suppressing filtering and discharging system provided by the invention, by means of the height difference (or level difference) between the sea water liquid level and the pressure-suppressing pond and the temperature difference between the sea water and the liquid phase in the pressure-suppressing pond under the accident condition, and by respectively arranging the heat exchangers on the pressure-suppressing pond and the sea water side, a natural circulation loop is constructed, so that the non-time-limit export of the heat of the pressure-suppressing pond under the accident condition can be realized, and the pressure-suppressing performance of the containment pressure-suppressing filtering and discharging system and the removal efficiency of airborne radioactive substances are improved.
Drawings
Fig. 1 shows a schematic structural view of a containment, pressure-suppressing, filtering and venting system in accordance with the present invention.
The device comprises a 1-containment, a 2-discharge valve, a 3-discharge pipeline, a 4-spray pipe, a 5-first-stage pressure-restraining water tank, a 6-second-stage pressure-restraining water tank, a 7-expansion chamber, an 8-discharge valve, a 9-steam-water separator, a 10-combined metal fiber filter layer, a 11-valve, a 12-rupture membrane, a 13-valve, a 14-flow-limiting pore plate, a 15-radioactivity monitor, a 16-pressure-restraining water tank heat exchanger, a 17-seawater side heat exchanger and 18-seawater.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
The containment pressure-suppressing filtering and discharging system is based on 2-level bubbling washing-metal fiber filtering integration, and mainly comprises discharge valves (2 and 8), a discharge pipeline 3, a spray pipe 4, a first-level pressure-suppressing water tank 5, a second-level pressure-suppressing water tank 6, a capacity expansion chamber 7, a steam-water separator 9, a combined metal fiber filtering layer 10, a rupture disk 12, a flow-limiting pore plate 14, a radioactivity monitor 15, a pressure-suppressing water tank heat exchanger 16, a seawater side heat exchanger 17 and valves (11 and 13), as shown in fig. 1. In particular, the method comprises the steps of,
The safety shell 1 is communicated with the first-stage pressure-restraining pond 5 through a discharge pipeline 3, the joint position of the discharge pipeline 3 and the safety shell 1 is located at the upper part of the safety shell 1, a discharge valve 2 is arranged at the top of the discharge pipeline 3 and located outside the safety shell 1 and closely abuts against the safety shell, a spray pipe 4 is arranged at the tail end of the discharge pipeline 3 in a vertically downward installation mode and located at the bottoms of the first-stage pressure-restraining pond 5 and the second-stage pressure-restraining pond 6, and the bottoms of the first-stage pressure-restraining pond 5 and the second-stage pressure-restraining pond 6 are communicated and are internally loaded with mixed solution of sodium hydroxide and sodium thiosulfate.
The repression water tank heat exchanger 16 is arranged in the first-stage repression water tank 5, the seawater side heat exchanger 17 is positioned in seawater, and the seawater side heat exchanger 17 is higher than the repression water tank heat exchanger 16. The top pipeline of the repressing water pool heat exchanger 16 is connected with the top pipeline of the seawater side heat exchanger 17, and the bottom pipeline of the repressing water pool heat exchanger 16 is connected with the bottom pipeline of the seawater side heat exchanger 17, so that a natural circulation loop is constructed.
The expansion chamber 7 is arranged at one side of the second-stage repression water tank 6 and is communicated with the second-stage repression water tank 6 through a pipeline;
The steam-water separator 9 and the combined metal fiber filter layer 10 are arranged at the upper part of the interior of the expansion chamber 7 and are adjacently connected, in addition, the steam-water separator 9 is arranged at the relative position of a pipeline which is communicated with the expansion chamber 7 and the combined metal fiber filter layer 10, the discharge valve 8 is arranged at the upstream of the steam-water separator 9, and the burst membrane 12 is arranged at the downstream of the combined metal fiber filter layer 10 and is positioned on a filter discharge pipeline which is connected with the combined metal fiber filter layer 10. The opening pressure of the discharge valve 8 is smaller than the design bearing pressure of the containment 1, the first-stage pressure-restraining water tank 5 and the second-stage pressure-restraining water tank 6, the opening pressure of the rupture disk 12 is the same as the opening pressure of the discharge valve 8, and a plurality of metal fiber layers which are stacked in a combined mode and have different meshes and different wire diameters are arranged in the combined metal fiber filter layer 10.
A parallel pipeline is arranged in the pipeline where the rupture disk 12 is arranged, and a valve 13 which can be opened manually is arranged in the parallel pipeline. In addition, a valve 11 is arranged in the containment 1 for respectively communicating or isolating the containment and the repression water pool or/and the dilatation chamber. A restriction orifice (14) and a radioactivity monitor (15) are arranged at the downstream of the filter discharge line.
The containment pressure-restraining filtering discharge system provided by the embodiment is suitable for a floating nuclear power platform and is used for depressurization of the containment and removal of radioactive substances after an accident of the floating nuclear power platform.
First, under normal working conditions, all valves in the containment pressure-suppressing filter exhaust system of the present embodiment are in a closed state. And (3) nitrogen is filled into the whole containment pressure-restraining filtering discharge system so as to reduce the risk of hydrogen explosion in the system under the accident condition.
When LOCA accident occurs in a first circuit in the containment 1, the containment pressure-restraining filtering discharge method comprises the following steps.
Step S1, when the pressure of the containment vessel is increased to the opening pressure of the discharge valve 2, the discharge valve 2 is automatically opened, a high-temperature and high-pressure steam-air mixture (namely, discharge gas, including radioactive substances such as aerosol and iodine) in the containment vessel is bubbled into the first-stage pressure-suppressing water tank 5 and the second-stage pressure-suppressing water tank 6 through the discharge pipeline 3 and the nozzle 4, and the discharge gas is directly contacted with a solution in the pressure-suppressing water tank (namely, a mixed solution of sodium hydroxide and sodium thiosulfate) to be condensed by bubbling, so that efficient heat exchange is performed, the rapid depressurization of the containment vessel 1 is realized, and the pressure peak of the containment vessel 1 in the initial stage of an accident is reduced. In addition, the mixed solution of sodium hydroxide and sodium thiosulfate loaded in the pressure-inhibiting water tank can absorb iodine in the exhaust gas through chemical reaction.
Specifically, in the first-stage bubbling condensation and water washing in the first-stage pressure-suppressing water tank 5, the gas at the outlet of the spray pipe 4 is in a high-speed jet state, and the liquid phase is entrained into the gas plume to form a large number of entrained liquid drops. The aerosol is captured and removed by the entrained droplets through capture mechanisms such as inertial collision, interception, brownian diffusion and the like, and the radioactive iodine is absorbed by the entrained droplets. Meanwhile, the steam share of the exhaust gas is higher, and the steam condensation can also obviously improve the removal efficiency of the aerosol. As the energy of the exhaust gas dissipates, the gas flow pattern is changed from jet flow to bubble group. The radioactive substance diffuses and migrates to the surface of the bubble in the bubble and is retained by the liquid phase. After bubbling heat exchange of the first-stage pressure-inhibiting water tank, the discharged gas mainly remains non-condensable gas.
The discharged gas after passing through the first-stage pressure-restraining water tank 5 enters the second-stage pressure-restraining water tank 6 to carry out second-stage bubbling heat exchange and water washing.
In addition, in the step S1, by means of the height difference between the liquid level of the seawater 18 and the first-stage pressure-restraining pond 5 and the temperature difference between the seawater and the liquid phase in the first-stage pressure-restraining pond 5 under the accident condition, a natural circulation loop is constructed through the heat exchangers 16/17 which are arranged on the first-stage pressure-restraining pond 5 and the seawater 18 side and are filled with desalted water, the non-time limit export of the heat of the pressure-restraining pond under the accident condition is realized, and the pressure-restraining performance of the containment pressure-restraining filtering emission system and the removal efficiency of airborne radioactive substances are improved.
And S2, when the pressure in the pressure restraining water tanks (5 and 6) or the expansion chamber 7 is higher than the pressure of the containment vessel 1, opening the valve 11 to release the pressure of the pressure restraining water tanks and the expansion chamber, and when the pressure in the containment vessel 1 is higher than the pressure of the pressure restraining water tanks 5/6 again, carrying out the process in the step S1 again, so that the pressure restraining water tanks (5 and 6) realize the functions of pressure restraining and water washing again.
And S3, enabling the exhaust gas subjected to two-stage bubbling heat exchange and water washing to enter the expansion chamber 7, removing carried liquid drops from the exhaust gas through the steam-water separator 9, and enabling the exhaust gas to flow through the combined metal fiber filter layer 10 to realize filtration of high-temperature and high-pressure gas in the containment vessel 1, the pressure inhibition pools (5 and 6) and the expansion chamber 7, wherein the filtered gas is discharged through the rupture disk 12 or the valve 13. The combined metal fiber filter layer is provided with a plurality of metal fiber layers which are combined and stacked in different meshes and different wire diameters, and can realize the efficient capture of small-particle-size aerosol.
Specifically, since the opening pressure of the rupture disk 12 arranged downstream of the metal fiber filter layer 10 is the same as the opening pressure of the discharge valve 8, when the pressures of the pressure-suppressing reservoirs (5 and 6) and the expansion chamber 7 reach the opening pressure of the discharge valve 8, the discharge valve 8 and the rupture disk 12 are opened first and then, so that the filtration discharge of the high-temperature and high-pressure gas in the containment vessel 1, the pressure-suppressing reservoirs (5 and 6) and the expansion chamber 7 is realized.
When the rupture disc fails to be opened, the valve 13 arranged on the parallel pipeline of the pipeline where the rupture disc 12 is positioned is opened electrically and remotely or manually in situ, so that the filtration and the discharge of the high-temperature and high-pressure gas in the containment vessel 1, the pressure-restraining pools (5 and 6) and the expansion chamber 7 are realized.
Step S4, the filtered gas is restrictively discharged through a flow limiting orifice plate 14 arranged on a filtering and discharging pipeline, so that the discharge flow is ensured to be basically consistent with the design flow of the filtering and discharging system in a period of time, the filtering efficiency of the system is ensured, and meanwhile, the radioactivity monitor 15 is used for monitoring the radioactive dose released into the environment and can also be used for monitoring the filtering capacity of the system on radioactive substances.
The above examples are only preferred embodiments of the present invention, but the present invention is not limited to the examples and the disclosure of the drawings. It should be noted that modifications and equivalent changes can be made by those skilled in the art without departing from the principles of the present invention, which are to be considered as falling within the scope of the present invention.
Claims (10)
1. A containment pressure-suppressing filtering and discharging system is characterized in that,
The containment pressure-restraining filtering and discharging system comprises a discharging valve (2), a discharging pipeline (3), a spray pipe (4), a pressure-restraining water tank, a capacity expansion chamber (7), a steam-water separator (9), a metal fiber filter layer (10), a rupture disk (12), a heat exchanger and a valve,
The containment vessel (1) is communicated with the pressure-restraining water tank through the discharge pipe (3), and the interface position of the discharge pipe (3) and the containment vessel (1) is positioned at the upper part of the containment vessel (1);
The discharge valve (2) is arranged at the top of the discharge pipeline (3) and is positioned outside the containment vessel (1);
the spray pipe (4) is arranged at the tail end of the discharge pipeline (3) and is positioned at the bottom of the pressure-restraining water tank, the expansion chamber (7) is arranged at one side of the pressure-restraining water tank, and the expansion chamber (7) is communicated with the pressure-restraining water tank through a pipeline;
the steam-water separator (9) and the metal fiber filter layer (10) are arranged at the upper part of the inside of the expansion chamber (7), and the steam-water separator (9) and the metal fiber filter layer (10) are adjacently connected;
the rupture disk (12) is located on a filter drain line connected to the metal fiber filter layer (10);
The heat exchanger comprises a pressure-restraining pool heat exchanger (16) and a seawater side heat exchanger (17).
2. The containment, pressure-suppressing, filtering and discharging system according to claim 1, characterized in that said spout (4) is mounted vertically downwards, or/and
The pressure-restraining water tank comprises a multi-stage sub-pressure-restraining water tank, or/and
The interior of the pressure-inhibiting water tank is filled with mixed solution of sodium hydroxide and sodium thiosulfate, or/and
The tube side of the heat exchanger is filled with desalted water.
3. The containment, pressure-suppressing, filtering and venting system as recited in claim 2, wherein,
The pressure restraining water tank comprises a first-stage pressure restraining water tank (5) and a second-stage pressure restraining water tank (6), and communicating pipes are arranged at the bottoms of the first-stage pressure restraining water tank (5) and the second-stage pressure restraining water tank (6).
4. A containment, hold-down, filtration and discharge system according to claim 3, characterized in that the hold-down tank heat exchanger (16) is arranged inside the first stage hold-down tank (5), or/and
The seawater side heat exchanger (17) is positioned in the seawater, and the seawater side heat exchanger (17) is positioned higher than the height of the repression water tank heat exchanger (16), or/and
The top pipeline of the pressure-restraining water tank heat exchanger (16) is connected with the top pipeline of the seawater side heat exchanger (17), and the bottom pipeline of the pressure-restraining water tank heat exchanger (16) is connected with the bottom pipeline of the seawater side heat exchanger (17), so that a natural circulation loop is constructed.
5. The containment pressure-suppressing filter discharge system according to claim 1, wherein the steam-water separator (9) is provided at a relative position of a pipe line communicating the expansion chamber (7) and the metal fiber filter layer, or/and
A discharge valve (8) is arranged at the upstream of the steam-water separator (9), a rupture membrane (12) is arranged at the downstream of the metal fiber filter layer (10), or/and
The steam-water separator adopts a folded plate type steam-water separator, or/and
The metal fiber filter layer adopts a combined metal fiber filter layer, and optionally, the combined metal fiber filter layer is provided with a plurality of metal fiber layers which are stacked in a combined way and have different meshes and different diameters.
6. The containment, pressure-suppressing, filtering and venting system as recited in claim 5, wherein,
The opening pressure of the discharge valve (8) is smaller than the design bearing pressure of the containment and the repressor pool, or/and
The burst disk (12) has a same opening pressure as the discharge valve (8).
7. The containment, pressure-suppressing, filtering and venting system as recited in claim 1, wherein,
A parallel pipeline is arranged on a pipeline where the rupture disk is positioned, a valve 13 is arranged on the parallel pipeline, the valve 13 can be opened electrically and remotely or manually, or/and
The inside of the containment is also provided with a valve 11 for respectively communicating or isolating the containment and the repression water pool or/and the dilatation chamber, or/and
The containment hold-down filter drain system further includes a filter drain line downstream of which a restrictor orifice (14) is disposed, or/and
A radioactivity monitor (15) is arranged downstream of the filter discharge line.
8. A containment pressure-suppressing filter discharge method employing the containment pressure-suppressing filter discharge system according to any one of claims 1 to 7, the containment pressure-suppressing filter discharge method comprising the steps of:
1) When LOCA accident occurs in the containment, after the pressure in the containment reaches the opening pressure of the discharge valve, the discharge valve can be automatically opened based on pressure difference, and the high-temperature high-pressure steam air mixture in the containment is bubbled into the pressure-restraining water tank through the spray pipe through the discharge pipe to carry out bubbling heat exchange and water washing;
Constructing a natural circulation loop by means of a height difference between the liquid level of the seawater and the first-stage pressure-suppressing pond and a temperature difference between the seawater and the liquid phase in the first-stage pressure-suppressing pond under accident conditions and a heat exchanger filled with desalted water on the pipe sides of the first-stage pressure-suppressing pond and the seawater side;
2) When the pressure of the pressure restraining water pool or the expansion chamber is higher than the pressure of the containment vessel, a valve connecting the pressure restraining water pool and the containment vessel or/and a valve connecting the expansion chamber and the containment vessel is/are opened to release the pressure of the pressure restraining water pool or/and the expansion chamber, and when the pressure of the containment vessel is higher than the pressure of the pressure restraining water pool again, the flow of the step 1) is carried out again;
3) The exhaust gas subjected to multistage bubbling heat exchange and water washing enters a capacity expansion chamber, and the containment pressure is further reduced by a pressure inhibition and capacity expansion method;
4) When the pressure of the containment or the pressure-restraining pool reaches the design pressure of filtration and discharge, a valve on a filtration and discharge pipeline is opened, the discharged gas firstly passes through a steam-water separator and then passes through a metal fiber filter layer to be filtered, and the filtered discharged gas passes through a rupture disk or a valve;
5) The exhaust gas passing through the rupture disk or valve is released into the environment through the orifice plate while the radioactive material released into the environment is monitored.
9. The containment, pressure-suppressing, filtering and venting method as recited in claim 8, wherein step 1) further comprises the steps of:
By utilizing the height difference between the sea water liquid level and the pressure-restraining pond and the temperature difference between the sea water and the liquid phase in the pressure-restraining pond under accident conditions, a natural circulation loop is constructed by arranging the heat exchanger of the pressure-restraining pond and the heat exchanger on the sea water side, the non-time-limit export of heat in the containment and the pressure-restraining pond is realized, and the water washing detention efficiency of the airborne radioactive substances is improved.
10. Use of the containment pressure-suppressing filter drain system of any one of claims 1-7 in a floating nuclear power platform.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202411719326.XA CN119833176A (en) | 2024-11-28 | 2024-11-28 | Containment pressure-restraining filtering discharge system and method and application thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202411719326.XA CN119833176A (en) | 2024-11-28 | 2024-11-28 | Containment pressure-restraining filtering discharge system and method and application thereof |
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| CN119833176A true CN119833176A (en) | 2025-04-15 |
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| CN202411719326.XA Pending CN119833176A (en) | 2024-11-28 | 2024-11-28 | Containment pressure-restraining filtering discharge system and method and application thereof |
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