Sea surface nuclear power plant steel containment suppression heat extraction device flushed by seawater

Abstract

The invention provides a sea surface nuclear power plant steel containment pressure suppression and heat extraction device showered by ocean. The sea surface nuclear power plant steel containment pressure suppression and heat extraction device comprises a seawater showering device, a containment, a pressure vessel, a steam generator and a pressure stabilizer, wherein the pressure vessel, the steam generator and the pressure stabilizer are arranged in the containment; the seawater showering device is connected into the ocean, so that the outer wall of the containment is showered by utilizing the ocean in the ocean; the pressure container is connected with the steam generator and the pressure stabilizer through a main pipeline, and a main pump is further arranged on the main pipeline between the pressure container and the steam generator. The characteristics of good heat conductivity and the like of the ocean infinite heat trap and the steel containment are fully utilized, the seawater shower device is arranged outside the containment, and heat exchange between high-temperature steam in the containment and seawater outside the containment is realized under the accident condition, so that heat of the containment is taken out in a long-term stage, and the integrity of the containment is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of sea surface nuclear power plants, and in particular to a pressure suppression and heat removal device for a steel containment shell of a sea surface nuclear power plant flushed with sea water. Background Art

[0002] During the normal operation of the marine nuclear power plant, the steel containment is at normal pressure and temperature or slightly negative pressure. When a loss of coolant accident (LOCA) occurs, the coolant in the primary circuit is discharged into the containment through the breach. Since the temperature and pressure of the primary circuit coolant are much higher than the containment temperature, part of the coolant discharged into the containment vaporizes, causing the temperature and pressure of the containment to rise rapidly. In particular, when a double-end shear fracture accident occurs in the hot section of the main pipeline, the coolant in the primary circuit is emptied in a very short time, causing the temperature and pressure of the containment to rise rapidly. When a secondary circuit main steam pipe rupture (SLB) accident occurs, the steam in the secondary circuit sprays out from the breach into the containment. Since the steam temperature and pressure of the secondary circuit are much higher than the containment, the temperature and pressure of the containment will rise rapidly. In particular, when a double-end shear fracture accident occurs in the generator main steam pipe, the steam in the secondary circuit is instantly discharged into the containment, causing the temperature and pressure of the containment to rise rapidly.

[0003] The containment design of offshore nuclear power plants is relatively compact. Therefore, when an accident occurs in which mass and energy is released into the containment, the temperature and pressure rise rapidly. Suppression water tanks are usually used to limit the pressure rise in the short term to prevent the containment from being damaged by overpressure. However, suppression water tanks can only be used for short-term suppression. When the water in the suppression water tank is saturated or the pressure in the suppression water tank is balanced with the pressure in the containment, the suppression water tank fails. Summary of the invention

[0004] The present invention provides a pressure suppression and heat removal device for a steel containment shell of a sea surface nuclear power plant using seawater flushing, the device comprising: a seawater flushing device, a containment shell, and a pressure vessel, a steam generator, and a pressurizer arranged in the containment shell; the seawater flushing device is connected to the ocean to use the seawater in the ocean to flush the outer wall of the containment shell;

[0005] The pressure vessel is connected to the steam generator and the pressure stabilizer through a main pipeline, and a main pump is also arranged on the main pipeline between the pressure vessel and the steam generator.

[0006] Optionally, the seawater flushing device comprises an external flushing head of the containment shell and a flushing pipeline, and seawater in the ocean is connected to the external flushing head of the containment shell via the flushing pipeline to flush the outer wall of the containment shell via the external flushing head of the containment shell;

[0007] The shower pipeline is also provided with a shower pump for controlling the seawater in the ocean to start or stop entering the shower head.

[0008] Optionally, the containment external shower head is located on the top and / or side wall of the containment;

[0009] The containment shell external shower heads are provided in one or more layers, and the number of the containment shell external shower heads in each layer is one or more.

[0010] Optionally, the seawater shower device further comprises a shower pipeline isolation valve, which is arranged on the shower pipeline and is used to block the seawater flowing into the shower pipeline.

[0011] Optionally, the shower line isolation valve comprises a first shower line isolation valve and a second shower line isolation valve;

[0012] The first shower line isolation valve and the second shower line isolation valve are respectively located on both sides of the shower pump.

[0013] Optionally, a pressure suppression water tank is also provided at the bottom end of the containment vessel.

[0014] Optionally, an external flushing water pool is provided outside the containment shell to collect flushing water flowing down from the outer wall of the containment shell; the external flushing water pool is connected to the ocean via a pool discharge pipeline. A pool discharge pipeline isolation valve is also provided on the pool discharge pipeline.

[0015] Optionally, a flushing water diversion device is provided outside the containment shell.

[0016] The present invention is aimed at sea-surface nuclear power plants and proposes a pressure suppression and heat removal device for a steel containment of a sea-surface nuclear power plant that uses seawater flushing. The device fully utilizes the infinite heat sink of the ocean and the good thermal conductivity of the steel containment, and a seawater flushing device is arranged outside the containment. Under accident conditions, heat exchange between the high-temperature steam in the containment and the seawater outside the containment is achieved, thereby removing the heat of the containment in a long period of time and ensuring the integrity of the containment.

[0017] When a primary circuit or a secondary circuit in a sea-based nuclear power plant breaches, the temperature and pressure of the containment will rise rapidly. In the short term, a suppression water tank will be used to limit the pressure rise in the containment. In the long term, a seawater flushing device will be used to complete the heat exchange between the high-temperature steam in the containment and the seawater outside the containment, thereby bringing out the heat in the containment and limiting the pressure rise in the containment. A pressure suppression and heat dissipation design scheme is proposed for the mass-energy release in the steel containment to ensure the integrity of the containment under accident conditions.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 This is a schematic diagram of containment pressure suppression and heat removal;

[0021] Figure 2 It is a schematic diagram of a pressure suppression and heat removal device for a steel containment vessel of a sea-surface nuclear power plant flushed with seawater according to an embodiment of the present invention;

[0022] Figure 1 Middle: 1a-pressure vessel; 2a-steam generator; 3a-pressurizer; 4a-main pump; 5a-break; 6a-main pipeline; 7a-containment; 8a-pressure suppression water tank; 9a-spray nozzle in containment; 10a-spray pump; 11a-spray pipeline isolation valve; 12a-spray recirculation pipeline isolation valve; 13a-direct spray pipeline isolation valve; 14a-recirculation spray heat exchanger; 15a-direct spray water source; 16a-recirculation spray shell bottom filter; 17a-containment shell bottom;

[0023] Figure 2 In: 1-pressure vessel; 2-steam generator; 3-pressurizer; 4-main pump; 5-breach; 6-main pipeline; 7-containment; 8-pressure suppression tank; 9-external flushing head of containment; 10-flushing pump; 11-1-isolation valve of the first flushing pipeline; 11-2-isolation valve of the second flushing pipeline; 12-flushing pipeline; 13-external flushing water storage tank of containment; 14-isolation valve of the discharge pipeline of the storage tank; 15-seawater. DETAILED DESCRIPTION

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0025] In addition, 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. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0026] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0028] When an offshore nuclear power plant needs to suppress pressure and cool down for a long period of time, spraying can be used to remove heat. The heat in the containment atmospheric space is first introduced into the spray water through direct spraying. The spray water is deposited at the bottom of the containment. When the spray water source is exhausted, the spray system is switched to recirculation. During the recirculation stage, the spray system takes water from the bottom of the containment, sprays the containment after passing through the recirculation spray heat exchanger, and conducts heat out of the containment through the spray heat exchanger. A schematic diagram of the containment suppression and heat removal system for an offshore nuclear power plant according to an embodiment is shown in FIG. Figure 1 As shown, this method requires a separate spray water source to be set up, and the temperature and pressure are reduced by spraying the inside of the containment.

[0029] The embodiment of the present invention also provides a pressure suppression and heat removal device for a steel containment vessel of a sea surface nuclear power plant flushed with seawater, such as Figure 2 As shown, the pressure suppression and heat removal device of the steel containment 7 of the marine nuclear power plant of this embodiment includes: a seawater flushing device, a containment 7, and a pressure vessel 1, a steam generator 2, and a pressurizer 3 arranged in the containment 7. The containment 7 can be a steel containment. The seawater flushing device is connected to the ocean to use the seawater in the ocean 15 to flush the outer wall of the containment 7, so as to play a cooling effect when the containment 7 is heated. The pressure vessel 1 is connected to the steam generator 2 and the pressurizer 3 through a main pipeline 6, and a main pump 4 is also arranged on the main pipeline 6 between the pressure vessel 1 and the steam generator 2. The pressure vessel 1, the main pipeline 6, the main pump 4, and the steam generator 2 form a primary loop system, which is used to take out the heat generated by the chain reaction of the reactor core. The heat of the primary loop is then transferred to the secondary loop through the steam generator. The function of the pressurizer is to control the pressure of the primary loop by means of electric heating and spraying of the pressurizer to ensure the normal operation of the reactor. The main function of the main pump 4 is to provide flow for the reactor primary loop system so that the primary loop coolant can flow as required, thereby removing the heat generated by the core chain reaction.

[0030] The outer side of the containment shell 7 is also provided with a containment shell external flushing water pool 13 for collecting flushing water flowing down from the outer wall of the containment shell 7; the containment shell external flushing water pool 13 is connected to the ocean via a pool discharge pipeline 14. The outer wall surface of the containment shell 7 is not in direct contact with the seawater, so a pool 7 is required to collect the flushed seawater and then discharge it into the sea through the pool discharge pipeline 14.

[0031] The water pool discharge pipeline 14 is also provided with a water pool discharge pipeline isolation valve 16. The main function of the water pool discharge pipeline isolation valve 16 is to isolate the water pool 13 and the seawater 15 when the reactor is operating normally. After an accident occurs, after the seawater flushing begins, the valve is opened and the water in the water pool is discharged into the ocean 7. The water pool 13 is located higher than the seawater, and the water in the water pool 13 can be discharged into the sea by opening the water pool discharge pipeline isolation valve 16. After the seawater flushing containment measures after the accident begin, the seawater on the outer wall of the containment 7 is collected in the water pool 13, and the water can be drained by opening the water pool discharge pipeline isolation valve 16.

[0032] Optionally, a drainage device may be provided outside the containment vessel of the nuclear power plant to discharge the water flushed outside the containment vessel back into the seawater to avoid the accumulation of seawater outside the containment vessel.

[0033] The outside of the containment 7 is provided with a flushing water guide device. The guide device can be a guide plate, a water retaining strip or other structures, so that when the seawater flushing device is in operation, the water film outside the containment is covered more evenly, thereby making full use of the heat-conducting wall surface of the containment. In practical applications, the seawater flushing device requires one or more pumps to extract seawater to flush the outer wall of the containment 7. The pump can be shared with other pumps under the condition that the functions do not conflict, so as to reduce the design burden. For example, a pump that can be shared is a seawater cooling system pump, which is a heat sink of the equipment cooling water system, that is, the system uses a pump to pump water from the ocean and discharges it into the sea after passing through the secondary side of the equipment cooling water heat exchanger. Thereby, the heat in the equipment cooling water system is brought into the ocean. The equipment coolant water system provides a heat sink for related systems such as the waste heat removal system. Its main function is to cool the reactor primary circuit coolant and introduce the heat generated by the reactor into the equipment cooling water system through the waste heat removal system heat exchanger.

[0034] Continue to see Figure 2The seawater flushing device includes an external flushing head 9 for containment and a flushing pipeline 12. The seawater in the ocean 15 is connected to the external flushing head 9 for containment via the flushing pipeline 12, so as to flush the outer wall of the containment 7 via the external flushing head 9 for containment; a flushing pump 10 is also provided on the flushing pipeline 12, which is used to control the seawater in the ocean 15 to start or stop entering the flushing head. The seawater flushing device also includes a flushing pipeline isolation valve, which is provided on the flushing pipeline 12. The flushing pipeline isolation valve includes a first flushing pipeline isolation valve 11-1 and a second flushing pipeline isolation valve 11-2; the first flushing pipeline isolation valve 11-1 and the second flushing pipeline isolation valve 11-2 are respectively located on both sides of the flushing pump 10. Among them, the second flushing pipeline isolation valve 11-2 close to the seawater side mainly functions to protect the pump from seawater erosion, and the first flushing pipeline isolation valve 11-1 close to the flushing head side functions to isolate it from the flushing head. If the pump is performing other functions (for example, when the pump is cooling the community cooling water system), the containment will not be flushed, and the flushing function will only be performed after the valve is opened.

[0035] The containment shell external shower head 9 is located at the top and / or side wall of the containment shell 7; the containment shell external shower head 9 is provided with one or more layers, and the number of the containment shell external shower heads 9 in each layer is one or more, which is not limited in the embodiment of the present invention.

[0036] The seawater flushing device outside the containment 7 in the embodiment of the present invention has the same main function as the spraying system of the containment 7, but compared with the spraying system inside the containment 7, the system reduces the spraying water source, does not require the switching of the recirculation process, and therefore does not require a recirculating heat exchanger, which reduces the equipment and water source overall, and reduces the design burden and operation and maintenance burden. The seawater spraying device of this embodiment can replace the containment spraying system to perform the containment heat carrying function, or cooperate with the containment spraying system to jointly complete the heat extraction of the containment 7.

[0037] The seawater shower device disposed outside the containment 7 in the embodiment of the present invention can independently perform the heat extraction function of the containment 7, or can cooperate with the spray system to perform the function. That is, the shower device of this embodiment can independently undertake the function of cooling the containment, and if a spray system is provided inside the containment, it can also cooperate with the spray system inside the containment to jointly undertake the function of cooling the containment.

[0038] Normally, the containment 7 is used in conjunction with a pressure suppression water tank when its volume is small and the design pressure is low. The pressure suppression water tank solves the problem of short-term pressure suppression in the containment, and the seawater flushing device solves the problem of long-term heat generation. Therefore, optionally, a pressure suppression water tank 8 may also be provided at the bottom of the containment 7. When the free volume of the containment is large and the design pressure is high, the pressure suppression water tank may not be used, and the mass and energy release of the short-term primary or secondary circuits are contained by the containment, while the heat generation is achieved by cooperating with the external flushing system of the containment to achieve long-term heat generation.

[0039] The working principle of the suppression water tank is as follows: after a loss of coolant accident occurs, the coolant in the reactor is released into the containment through the rupture, causing the pressure in the containment to increase. After the containment pressure increases, a pressure difference is generated between the containment and the air space of the suppression water tank. Driven by the pressure difference, the mixed gas of water vapor and air in the containment enters the water of the suppression water tank through the suppression water tank drain pipe, where the steam condenses in the water of the suppression water tank and the non-condensable gas enters the air space of the suppression water tank. Due to the continuous flow of steam into the suppression water pool, the pressure increase of the containment is suppressed, ensuring that the integrity of the containment is not damaged.

[0040] Combination Figure 2 When a primary loop system pipeline breach accident LOCA or a main steam pipeline breach accident SLB occurs, the primary or secondary loop coolant is sprayed from the breach 5 into the containment 7, causing the temperature and pressure of the containment 7 to rise rapidly. In the short term after the accident, the suppression water tank 8 is put into operation. Driven by the pressure difference, the mixed gas of water vapor and air enters the water in the suppression water tank through the suppression water tank discharge pipe. In the suppression water tank 8, the steam is directly contacted with the cold water and condensed, and the non-condensable gas enters the gas space of the suppression water tank 8, thereby achieving short-term suppression of the containment 7.

[0041] After an accident occurs, the pressure in the containment will increase. The pressure sensor inside the containment detects the pressure increase and transmits the signal to the reactor protection system. The reactor protection system generates a signal for flushing the containment after logical judgment. Therefore, when the pressure in the containment 7 increases, the seawater flushing device outside the containment 7 is triggered according to the signal, the first flushing pipeline isolation valve 11-1 and the second flushing pipeline isolation valve 11-2 are opened, and the flushing pump 10 is started. After taking seawater from the ocean 15, the outer wall of the containment 7 is flushed through the flushing head 9 outside the containment. The flushed water enters the flushing water pool 13 outside the containment. In this process, the isolation valve 14 of the water pool discharge pipeline on the pipeline connecting the flushing water pool 13 outside the containment to the ocean 15 is opened, and the water in the flushing water pool 13 outside the containment is discharged into the ocean 15.

[0042] The specific operation process of the pressure suppression and heat removal device for the steel containment of a nuclear power plant on the sea surface flushed with seawater according to the embodiment of the present invention is as follows:

[0043] (1) When a breach occurs in the primary or secondary circuit, the temperature and pressure in the containment vessel 7 increase, and during this process the suppression pool will automatically start operation.

[0044] (2) When the pressure of the containment 7 rises to the trigger setting value of the seawater flushing device, the start signal of the flushing device outside the containment 7 is triggered.

[0045] (3) After the start signal of the seawater flushing device outside the containment is triggered, the following equipment will be operated in sequence: the first flushing pipeline isolation valve 11-1 and the second flushing pipeline isolation valve 11-2 on the flushing pipeline 12 are opened, the flushing pump 10 is started, and the water storage tank discharge pipeline isolation valve 14 is opened.

[0046] (4) After the flushing pump 10 is started, seawater passes through the flushing pipeline 12 and the flushing pump 10 to flush the outer wall of the containment shell 7. At this time, the containment shell 7 is filled with high-temperature and high-pressure water vapor. Under the action of flushing outside the shell, the steam close to the shell wall in the containment shell 7 condenses on the inner wall of the containment shell 7, and forms natural convection in the containment shell 7. The steam continues to condense and heats the inner wall of the containment shell 7 at the same time. The outer wall of the containment shell 7 is cooled by the flushing water, thereby realizing heat exchange between the steam in the containment shell 7 and the flushing water outside the shell, and introducing heat into the ocean 15.

[0047] (5) After being heated on the outer wall of the containment vessel 7, the flushing water first enters the flushing water pool 13 outside the containment vessel, and then enters the ocean 15 through the drainage pipeline.

[0048] The embodiment of the present invention proposes a seawater flushing containment pressure suppression and heat removal device for a sea-surface nuclear power plant. Based on the fact that the sea-surface nuclear power plant can utilize the infinite heat sink of the ocean and the good thermal conductivity of the steel containment, a seawater flushing device is arranged outside the containment 7. The device includes an external containment flushing pump 10, a flushing pipeline 12, a first flushing pipeline isolation valve 11-1, a second flushing pipeline isolation valve 11-2, an external containment flushing head 9, an external containment flushing water accumulation pool 13, and an accumulation pool discharge pipeline isolation valve 14. The heat removal of the containment 7 can be achieved through this system.

[0049] The embodiment of the present invention provides a seawater flushing containment pressure suppression and heat removal device for a sea-surface nuclear power plant. By providing a seawater flushing device, the following advantages are achieved:

[0050] 1. Traditional internal spraying requires the installation of a spray water source, which not only requires the installation of a water tank, but also the water source and water quality, which has an obvious design burden. However, this water source is useless in normal operation, and it is necessary to regularly maintain the water tank and ensure that the water quality meets the requirements, which is a burden on the nuclear power plant. The embodiment of the present invention adopts the method of flushing seawater outside the containment, which does not require the installation of a water source and reduces the design burden; there is no need to maintain the water tank and water quality, which reduces the operation and maintenance burden.

[0051] 2. The traditional spray system inside the containment has limited water source and can only maintain spraying for a period of time. The embodiment of the present invention adopts the seawater spraying method outside the containment, which can be used for a long time without worrying about the water source running out.

[0052] 3. The traditional spray system in the containment, when the water source of the spray system is exhausted, switches to the recycling mode of the bottom water in the containment. Since the temperature of the bottom water is high at this time, it cannot meet the long-term heat demand, so it is necessary to add an additional recycling heat exchanger to cool the bottom water to meet the long-term spraying requirements. The present invention adopts the flushing mode of seawater outside the containment 7, and utilizes the characteristics of the infinite heat sink of seawater and the good thermal conductivity of the steel containment 7 to achieve long-term cooling and save the recycling process. Therefore, the spray heat exchanger and its supporting system in the recycling stage can be reduced, reducing the design and operation and maintenance burden.

[0053] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A pressure suppression and heat removal device for a steel containment vessel of a sea-surface nuclear power plant flushed with seawater, characterized in that: The device comprises: a seawater flushing device, a containment shell (7), and a pressure vessel (1), a steam generator (2), and a pressurizer (3) arranged in the containment shell (7); the seawater flushing device is connected to the ocean so as to use seawater in the ocean to flush the outer wall of the containment shell (7); The pressure vessel (1) is connected to the steam generator (2) and the pressure stabilizer (3) via a main pipeline (6), and a main pump (4) is also provided on the main pipeline (6) between the pressure vessel (1) and the steam generator (2).

2. The device according to claim 1, characterized in that The seawater flushing device comprises an external flushing head (9) for the containment vessel and a flushing pipeline (12), wherein seawater in the ocean is connected to the external flushing head (9) for the containment vessel via the flushing pipeline (12) so as to flush the outer wall of the containment vessel (7) via the external flushing head (9); The shower pipeline (12) is also provided with a shower pump (10) for controlling the seawater in the ocean to start or stop entering the shower head.

3. The device according to claim 2, characterized in that The containment shell external shower head (9) is located on the top and / or side wall of the containment shell (7); The containment shell external shower heads (9) are provided in one or more layers, and the number of the containment shell external shower heads (9) in each layer is one or more.

4. The device according to claim 2, characterized in that The seawater flushing device also includes a flushing pipeline isolation valve, which is arranged on the flushing pipeline (12).

5. The device according to claim 4, characterized in that The shower line isolation valve comprises a first shower line isolation valve (11-1) and a second shower line isolation valve (11-2); The first shower line isolation valve (11-1) and the second shower line isolation valve (11-2) are respectively located on both sides of the shower pump (10).

6. The device according to any one of claims 1 to 5, characterized in that A pressure suppression water tank (8) is also provided at the bottom of the containment shell (7).

7. The device according to any one of claims 1 to 5, characterized in that An external flushing water pool (13) is also provided on the outside of the containment shell (7) for collecting flushing water flowing down from the outer wall of the containment shell (7); the external flushing water pool (13) is connected to the ocean via a pool discharge pipeline (14).

8. The device according to claim 7, characterized in that The water storage tank discharge pipeline (14) is also provided with a water storage tank discharge pipeline isolation valve (16).

9. The device according to claim 7, characterized in that A flushing water diversion device is arranged outside the containment shell (7).

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