Pressurized Water Reactor Nuclear Power Plant Heat Removal System and Method

Abstract

The present invention discloses a heat export system and method for a pressurized water reactor nuclear power plant. The heat export system for the pressurized water reactor nuclear power plant includes a cooling pool, a water storage tank, a feed water pipeline, and a steam pipeline; the water storage tank is arranged in the cooling pool; the feed water pipeline is connected between the outlet of the water storage tank and the auxiliary feed water pipeline of the steam generator; the steam pipeline is connected between the inlet of the water storage tank and the discharge pipeline of the steam generator; the steam generator is communicated with the outlet of the water storage tank through the auxiliary feed water pipeline and the feed water pipeline; the steam generator is communicated with the inlet of the water storage tank through the discharge pipeline and the steam pipeline, and releases the internally generated steam and sends it into the water storage tank. The present invention is used to export the heat of the steam generator as an auxiliary means when other heat export means fail under severe accidents in the nuclear power plant, and can effectively cool the secondary side of the steam generator and complete the heat export of the reactor core to ensure the integrity of the reactor core.

Description

Technical Field

[0001] The present invention relates to the technical field of heat conduction in pressurized water reactor nuclear power plants, and particularly to a heat export system and method for a pressurized water reactor nuclear power plant. Background Art

[0002] In a nuclear power plant, under normal or severe accident conditions, heat export from the primary circuit is the most basic means to ensure reactor safety and radioactive shielding. Heat in the primary circuit of a pressurized water reactor nuclear power plant is usually exported by the following means: 1. Cooling through steam discharge of the steam generator; 2. Through the residual heat removal system of the primary circuit; 3. Injecting through the safety injection system of the primary circuit and cooperating with break discharge, etc. Due to problems such as limited injection capacity of the safety injection system of the primary circuit, a certain failure probability of the residual heat removal system, radioactive leakage in the case of steam generator heat transfer tube rupture during steam generator discharge, and low cooling efficiency of the passive residual heat removal system on the secondary side, there is a risk that the above-mentioned residual heat removal means are unavailable under severe accident conditions.

[0003] Therefore, it is necessary to design a device that can circulate and export heat to the ultimate heat sink to ensure reactor safety under severe accident conditions. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a heat export system and a heat export method for a pressurized water reactor nuclear power plant for realizing secondary side heat export under severe accident conditions.

[0005] The technical solution adopted by the present invention to solve its technical problem is: to provide a heat export system for a pressurized water reactor nuclear power plant, including a cooling pool for accessing seawater, a water storage tank for storing coolant, a water supply pipeline, and a steam pipeline;

[0006] The water storage tank is arranged in the cooling pool and is cooled by heat exchange with seawater;

[0007] The water supply pipeline is connected between the outlet of the water storage tank and the auxiliary feed water pipeline of the steam generator to connect the water storage tank and the auxiliary feed water pipeline;

[0008] The steam pipeline is connected between the inlet of the water storage tank and the discharge pipeline of the steam generator to connect the water storage tank and the discharge pipeline;

[0009] The steam generator is connected to the outlet of the water storage tank through the auxiliary feed water pipeline and the water supply pipeline to receive the coolant from the water storage tank; the steam generator is connected to the inlet of the water storage tank through the discharge pipeline and the steam pipeline to discharge the internally generated steam and send it into the water storage tank, thereby exporting the heat of the steam generator.

[0010] Preferably, the feed water pipeline includes a feed water pipe, a feed water pump, a first isolation valve, and a second isolation valve;

[0011] The feed water pump is arranged on the feed water pipe, and the first isolation valve and the second isolation valve are respectively arranged on the feed water pipe corresponding to the inlet end and the outlet end of the feed water pump.

[0012] Preferably, the feed water pump is a diesel engine feed water pump.

[0013] Preferably, the heat removal system of the pressurized water reactor nuclear power plant further includes a circulation pipeline and a circulation valve; the circulation pipeline is connected between the outlet end of the feed water pump and the water storage tank to form a coolant circulation loop; the circulation valve is arranged on the circulation pipeline.

[0014] Preferably, the steam pipeline includes a steam pipe, a third isolation valve, a regulating valve, and a pressure detection device;

[0015] The third isolation valve is arranged on the steam pipe and close to the discharge pipe; the regulating valve and the pressure detection device are arranged on the steam pipe, and the regulating valve is located between the pressure detection device and the inlet of the water storage tank.

[0016] Preferably, the cooling pond is further provided with a water gate for controlling the connection and disconnection between the cooling pond and the open sea.

[0017] Preferably, the heat removal system of the pressurized water reactor nuclear power plant further includes a safety valve arranged on the water storage tank;

[0018] The setting value of the safety valve is higher than the setting value of the safety valve on the steam generator.

[0019] The present invention also provides a method for heat removal of a pressurized water reactor nuclear power plant, adopting the heat removal system of the pressurized water reactor nuclear power plant described in any one of the above, and the method for heat removal of the pressurized water reactor nuclear power plant includes the following steps:

[0020] Under severe accident conditions, the steam generator and the water storage tank are connected through the feed water pipeline, and the steam generator and the water storage tank are connected through the steam pipeline; the coolant in the water storage tank enters the steam generator through the feed water pipeline, and the steam and / or hot water generated inside the steam generator enters the water storage tank through the steam pipeline;

[0021] Wherein, the water storage tank is cooled by exchanging heat with the seawater in the cooling pond.

[0022] Preferably, under severe accident conditions, when the heat transfer tubes of the steam generator do not rupture, record the current internal pressure of the steam generator, and on the premise of maintaining the stability of the internal pressure, continuously transfer the coolant in the water storage tank to the steam generator, while the steam generator continuously discharges steam to the water storage tank.

[0023] Preferably, under severe accident conditions, when the heat transfer tubes of the steam generator rupture, set a set value. The steam generator is gradually filled with primary side water through the leakage of the heat transfer tubes, and the coolant in the water storage tank is also transferred to the steam generator. The steam generator discharges the internally generated steam and / or hot water to the water storage tank, so that the internal pressure of the water storage tank slowly rises under the set value.

[0024] The beneficial effects of the present invention: It is used to export the heat of the steam generator as an auxiliary means when other residual heat removal means fail under severe accidents in nuclear power plants. Among them, by injecting coolant through a feed water pump, steam release powered by the pressure in the steam generator, and seawater cooling, the secondary side of the steam generator can be effectively cooled, and the core heat can be exported to ensure the integrity of the core. Brief Description of the Drawings

[0025] The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0026] Figure 1 is a connection block diagram of a heat export system for a pressurized water reactor nuclear power plant according to an embodiment of the present invention. Detailed Embodiments

[0027] In order to have a clearer understanding of the technical features, objectives, and effects of the present invention, the detailed embodiments of the present invention will now be described in detail with reference to the drawings.

[0028] As Figure 1 shown, a heat export system for a pressurized water reactor nuclear power plant according to an embodiment of the present invention may include a cooling pool 10, a water storage tank 20, a feed water pipeline 30, and a steam pipeline 40.

[0029] The cooling pool 10 can be set near the sea for accessing seawater and using seawater as a cooling medium. Correspondingly, a water gate 11 is provided on the cooling pool 10 for opening or closing the cooling pool 10 to realize the connection and disconnection between the cooling pool 10 and the open sea. The water storage tank 20 is arranged in the cooling pool 10 and is used to store coolant (usually demineralized water) inside. In the cooling pool 10, the water storage tank 20 is cooled by heat exchange with seawater, so that the heat of the water storage tank 20 is taken away by seawater.

[0030] The water supply pipeline 30 is connected between the outlet of the water storage tank 20 and the auxiliary water supply pipeline 110 on the steam generator 100, connecting the water storage tank 20 and the auxiliary water supply pipeline 110. The steam pipeline 40 is connected between the inlet of the water storage tank 20 and the exhaust pipeline 120 on the steam generator 100, connecting the water storage tank 20 and the exhaust pipeline 120.

[0031] The steam generator 100 is connected to the outlet of the water storage tank 20 through the auxiliary water supply pipe 110 and the water supply pipeline 30, and receives the coolant from the water storage tank 20. The steam generator 100 is connected to the inlet of the water storage tank 20 through the exhaust pipe 120 and the steam pipeline 40, and discharges the steam generated inside and sends it to the water storage tank 20, thereby extracting the heat of the steam generator 100. The heat of the steam generator 100 is brought to the water storage tank 20 through the entry of the coolant and the discharge of the steam, and then taken away by the seawater through heat exchange with the seawater.

[0032] The water supply pipeline 30 further includes a water supply pipeline 31, a water supply pump 32, a first isolation valve 33 and a second isolation valve 34. The water supply pipeline 31 is connected between the outlet of the water storage tank 20 and the auxiliary water supply pipeline 110 on the steam generator 100, and the coolant is transported to the steam generator 100 through the water supply pipeline 31. The water supply pipeline 31 can be connected to the auxiliary water supply pipeline 110 of one or more steam generators 100 through a branch setting, so that the coolant can be provided to one or more steam generators 100 according to actual conditions when used.

[0033] The auxiliary water supply pipe 110 mentioned above is specifically an auxiliary water supply pipe of an auxiliary water supply system connected to the steam generator 100 .

[0034] The feed water pump 32 is arranged on the feed water pipeline 31, providing power to drive the coolant to be transported into the steam generator 100. The feed water pump 32 is preferably a diesel engine feed water pump, which can ensure the operation of the entire heat removal system without relying on power supply and remove the heat of the steam generator 100.

[0035] The first isolation valve 33 and the second isolation valve 34 are respectively arranged on the water supply pipe 31 corresponding to the inlet and outlet of the water supply pump 32. The opening and closing of the second isolation valve 34 can control the connection and disconnection between the water supply pipe 31 and the auxiliary water supply pipe 110. When the heat removal system does not need to be operated, the second isolation valve 34 remains closed.

[0036] In addition, the water tank 20 is also provided with a liquid level meter 12 for displaying the coolant level in the water tank 20. The liquid level meter 12 can be connected to the water supply pump 32 in communication, so that the water supply pump 32 will not start when the liquid level in the water tank 20 is at a low level, so as to maintain the minimum water volume in the water tank 20.

[0037] The steam pipeline 40 may further include a steam pipe 41, a third isolation valve 42, a regulating valve 43, and a pressure detection device 44. The steam pipe 41 is connected between the inlet of the water storage tank 20 and the discharge pipe 120 on the steam generator 100. The steam and / or hot water generated inside the steam generator 100 is released under the driving force of the pressure inside the steam generator 100 and is transported to the water storage tank 20 through the steam pipe 41.

[0038] The above-mentioned discharge pipe 120 is specifically the discharge pipe of the atmospheric discharge system connected to the steam generator 100; the discharge pipe 120 is usually connected to the steam outlet of the steam generator 100.

[0039] The third isolation valve 42 is arranged on the steam pipe 41 and close to the discharge pipe 120 to control the on-off between the steam pipe 41 and the discharge pipe 120. When the heat export system does not need to operate, the third isolation valve 42 remains closed.

[0040] Both the regulating valve 43 and the pressure detection device 44 are arranged on the steam pipe 41. Among them, the regulating valve 43 is located between the pressure detection device 44 and the inlet of the water storage tank 20. The pressure detection device 44 is used to detect the internal pressure of the steam pipe, and a pressure gauge is optional. The regulating valve 43 is used to adjust the internal pressure of the steam pipe 41 where it is located, so as to adjust the internal pressure of the water storage tank 20.

[0041] Furthermore, the heat export system of the pressurized water reactor nuclear power plant of the present invention may further include a safety valve 50, a circulation pipeline 60, and a circulation valve 61.

[0042] The safety valve 50 is arranged on the water storage tank 20, and its setting value is higher than that of the safety valve on the steam generator 100. The purpose of setting the safety valve 50 on the water storage tank 20 is as follows: to prevent the water storage tank 20 from overpressure damage when the entire heat export system is isolated; to serve as a backup for the safety valve of the steam generator 100 when the heat export system is put into operation to prevent overpressure of the relevant pipelines and the water storage tank 20.

[0043] In addition, the outlet of the safety valve 50 on the water storage tank 20 is connected to the RPE (nuclear island exhaust and drainage system) so that the fluid discharged after the safety valve 50 is opened is discharged to the RPE for recovery to prevent the leakage of radioactive substances.

[0044] The circulation pipeline 60 is connected between the outlet end of the feed water pump 32 and the water storage tank 20 to form a coolant circulation loop. The circulation valve 61 is arranged on the circulation pipeline 60 to control its on-off.

[0045] With the second isolation valve 34 in the closed state, starting the feed water pump 32 can drive the coolant in the water storage tank 20 to flow out, enter the feed water pump 32 through the first isolation valve 33, and then be output from the outlet end of the feed water pump 32 into the circulation pipeline 60, and then flow back to the water storage tank 20 through the circulation pipeline 60, thereby realizing the self-circulation of the coolant in the water storage tank 20 and verifying the availability of the feed water pump.

[0046] Furthermore, the heat removal system of the pressurized water reactor nuclear power plant of the present invention further includes a control device to realize the working mode selection, operation, etc. of the entire heat removal system. The control device may include a PID controller.

[0047] Among them, the regulating valve 43 and the pressure detection device 44 can be respectively communicatively connected to the control device. The control device can set the regulating valve 43 according to the required set value given by the set point station, and realize real-time monitoring in combination with the pressure value detected by the pressure detection device 44.

[0048] The heat removal system of the pressurized water reactor nuclear power plant of the present invention is applicable to severe accident conditions. When other heat removal means such as the atmospheric discharge system fails or is not used by decision, and the cooling effect of the passive residual heat removal system on the secondary side is not good, the reactor temperature cannot be stabilized. As an auxiliary means, the heat of the secondary side of the steam generator is removed, effectively realizing the cooling of the secondary side of the steam generator, completing the core heat removal, and ensuring the integrity of the core.

[0049] Reference Figure 1 , the heat removal method of the pressurized water reactor nuclear power plant realized by using the above heat removal system of the pressurized water reactor nuclear power plant may include the following steps:

[0050] Under severe accident conditions, the steam generator 100 and the water storage tank 20 are connected through the feed water pipeline 30, and the steam generator and the water storage tank 20 are connected through the steam pipeline 40; the coolant in the water storage tank 20 enters the steam generator 100 through the feed water pipeline 30, and the steam and / or hot water generated inside the steam generator 100 enters the water storage tank 20 through the steam pipeline 40.

[0051] Among them, the water storage tank 20 is cooled by exchanging heat with the seawater in the cooling pool 10, so that the steam entering the water storage tank 20 condenses back into a liquid.

[0052] Specifically, when the heat removal system of a pressurized water reactor nuclear power plant is activated, first open the water gate 11, and seawater enters the cooling pool 10, immersing the water storage tank 20 in seawater. Close the isolation valve 121 of the atmospheric discharge system, and open the third isolation valve 42 to connect the discharge pipe 120 and the steam pipe 41. Open the first isolation valve 33 and the second isolation valve 34 to connect the feed water pipe 31 and the auxiliary feed water pipe 110. After the feed water pump 32 is started, the coolant in the water storage tank 20 can enter the steam generator 100 through the feed water pipe 31 and the auxiliary feed water pipe 110. Steam is discharged from the top of the steam generator 100 and is transported to the water storage tank 20 through the steam pipe 41. The steam entering the water storage tank 20 condenses into a liquid after heat exchange with the seawater in the cooling pool 10.

[0053] Furthermore, under severe accident conditions, there are also the following two conditions: the non-steam generator heat transfer tube rupture condition (i.e., the heat transfer tube does not rupture) and the steam generator heat transfer tube rupture condition.

[0054] Corresponding to the above two conditions, when the heat transfer tubes of the steam generator 100 do not rupture, the specific steps are as follows:

[0055] The automatic mode (AUTO) can be selected through the control device without intervening in the internal pressure of the steam generator 100 and the related pipelines, and the memory unit records the current internal pressure of the steam generator 100.

[0056] On the premise of maintaining the internal pressure stable, start the feed water pump 32 to continuously transport the coolant in the water storage tank 20 into the steam generator 100, and at the same time, the steam generator 100 continuously discharges steam to the water storage tank 20. Among them, the steam discharged from the steam generator 100 is mainly released by the pressure in the steam generator 100 and does not require additional power.

[0057] When the heat transfer tubes of the steam generator 100 rupture, the specific steps are as follows:

[0058] The setting mode (MANU) can be selected through the control device, and a set value is set through the data provided by the setpoint station; this set value is lower than the set value of the safety valve on the steam generator 100.

[0059] Start the feed water pump 32 to transport the coolant in the water storage tank 20 into the steam generator 100. The steam generator 100 is gradually filled with primary side water through the leakage of the heat transfer tubes. The coolant in the water storage tank 20 is also transported into the steam generator 100. The steam generator 100 discharges the internally generated steam and / or hot water and sends it to the water storage tank 20, so that the internal pressure of the water storage tank 20 slowly rises under the set value. Among them, the steam and / or hot water discharged from the steam generator 100 are mainly released by the pressure in the steam generator 100 and do not require additional power.

[0060] During the above process, the primary side water leaking mainly from the heat transfer tubes inside the steam generator 100 gradually fills it up. Meanwhile, the water storage tank 20 also conveys the coolant into the steam generator 100 to assist in driving the circulation operation of the entire heat export system. At the same time, the steam pipeline 41 discharges steam; after the steam generator 100 is filled up, the steam pipeline 41 discharges hot water. While the primary side water gradually fills the steam generator 100, the water storage tank 20 also conveys the coolant into the steam generator 100 in coordination with the primary side water to drive the circulation operation of the entire heat export system.

[0061] It can be understood that when the pressurized water reactor nuclear power plant unit is operating normally, the heat export system of the pressurized water reactor nuclear power plant of the present invention is in an isolated state from the main system where the steam generator is located, where:

[0062] The second isolation valve 34 and the third isolation valve 42 are closed;

[0063] The water storage tank 20 stores the coolant (demineralized water) that meets the minimum operating requirements of the feed water pump 32;

[0064] The first isolation valve 33 and the circulation valve 61 are opened, and the feed water pump 32 operates regularly to verify its availability.

[0065] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. A heat removal system for a pressurized water reactor nuclear power plant, characterized in that, it includes a cooling pool for accessing seawater, a water storage tank for storing coolant, a feed water pipeline, and a steam pipeline; the water storage tank is arranged in the cooling pool and is cooled by heat exchange with seawater; the feed water pipeline is connected between the outlet of the water storage tank and the auxiliary feed water pipeline of the steam generator to connect the water storage tank and the auxiliary feed water pipeline; the steam pipeline is connected between the inlet of the water storage tank and the discharge pipeline of the steam generator to connect the water storage tank and the discharge pipeline; the steam generator is connected to the outlet of the water storage tank through the auxiliary feed water pipeline and the feed water pipeline to receive the coolant from the water storage tank; the steam generator is connected to the inlet of the water storage tank through the discharge pipeline and the steam pipeline to discharge the steam generated inside and send it into the water storage tank, thereby removing the heat of the steam generator; the feed water pipeline includes a feed water pipe, a feed water pump, a first isolation valve, and a second isolation valve; the feed water pump is arranged on the feed water pipe, and the first isolation valve and the second isolation valve are respectively arranged on the feed water pipe corresponding to the inlet end and the outlet end of the feed water pump; the heat removal system for the pressurized water reactor nuclear power plant further includes a circulation pipeline and a circulation valve; the circulation pipeline is connected between the outlet end of the feed water pump and the water storage tank to form a coolant circulation loop; the circulation valve is arranged on the circulation pipeline.

2. The heat removal system for the pressurized water reactor nuclear power plant according to claim 1, characterized in that, the feed water pump is a diesel engine feed water pump.

3. The heat removal system for the pressurized water reactor nuclear power plant according to claim 1, characterized in that, the steam pipeline includes a steam pipe, a third isolation valve, a regulating valve, and a pressure detection device; the third isolation valve is arranged on the steam pipe and is close to the discharge pipeline; the regulating valve and the pressure detection device are arranged on the steam pipe, and the regulating valve is located between the pressure detection device and the inlet of the water storage tank.

4. The heat removal system for the pressurized water reactor nuclear power plant according to claim 1, characterized in that, the cooling pool is also provided with a water gate for controlling the connection and disconnection between the cooling pool and the open sea.

5. The heat removal system for the pressurized water reactor nuclear power plant according to any one of claims 1-4, characterized in that, the heat removal system for the pressurized water reactor nuclear power plant further includes a safety valve arranged on the water storage tank; the set value of the safety valve is higher than the set value of the safety valve on the steam generator.

6. A heat removal method for a pressurized water reactor nuclear power plant, characterized in that, using the heat removal system for the pressurized water reactor nuclear power plant according to any one of claims 1-5, the heat removal method for the pressurized water reactor nuclear power plant includes the following steps: Under severe accident conditions, the steam generator and the water storage tank are connected through the feed water pipeline, and the steam generator and the water storage tank are connected through the steam pipeline; the coolant in the water storage tank enters the steam generator through the feed water pipeline, and the steam and / or hot water generated inside the steam generator enters the water storage tank through the steam pipeline; wherein, the water storage tank is cooled by heat exchange with the seawater in the cooling pool.

7. The method for removing heat from a pressurized water reactor nuclear power plant according to claim 6, It is characterized in that Under severe accident conditions, when the heat transfer tube of the steam generator has not ruptured, the current internal pressure of the steam generator is recorded, and the coolant in the water storage tank is continuously transported to the steam generator while maintaining the internal pressure stable. At the same time, the steam generator continuously discharges steam into the water storage tank.

8. The method for removing heat from a pressurized water reactor nuclear power plant according to claim 6, It is characterized in that Under severe accident conditions, when the heat transfer tube of the steam generator ruptures, a set value is set, the steam generator is gradually filled with primary side water through the leakage of the heat transfer tube, the coolant in the water storage tank is also transported to the steam generator, the steam generator discharges the steam and / or hot water generated inside and sends them to the water storage tank, so that the internal pressure of the water storage tank slowly increases at the set value.

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