A safety injection system and nuclear power plant

Abstract

The embodiment of the present invention provides a safety injection system and a nuclear power plant. The safety injection system is applied to a nuclear power plant. The nuclear power plant includes a reactor pressure vessel, N steam generators and N hot pipe segments. Each steam generator is connected to the reactor pressure vessel through a hot pipe segment. The safety injection system includes N safety injection units, N direct injection pipelines and N hot segment injection pipelines. N is a positive integer and N is greater than 1. Each safety injection unit is connected to the reactor pressure vessel through a direct injection pipeline and a hot segment injection pipeline. The safety injection unit includes: a safety injection box, which is connected to the reactor pressure vessel through a direct injection pipeline; a safety injection pump, which includes a first outlet pipe and a second outlet pipe, the first outlet pipe is connected to the reactor pressure vessel through a direct injection pipeline, and the second outlet pipe is connected to the hot pipe segment through a hot segment injection pipeline. The safety injection system provided by the embodiment of the present invention has high reliability.

Description

Technical Field

[0001] The invention relates to the field of safety facility design of nuclear power plants, and in particular to a safety injection system and a nuclear power plant. Background Art

[0002] The safety injection system is an important system for maintaining the safety of nuclear power plants. When a breach occurs in the primary circuit, the safety injection system is activated to inject coolant into the reactor core to ensure that the reactor core is well cooled and avoid more serious nuclear safety accidents caused by breach accidents.

[0003] The existing safety injection system generally includes a medium-pressure safety injection pump and a low-pressure safety injection pump arranged in parallel. The outlet pipes of the medium-pressure safety injection pump and the low-pressure safety injection pump are connected to the reactor pressure vessel through a hot pipe section and a cold pipe section respectively. If the parallel outlet pipes are damaged, the safety injection system will fail. Therefore, the reliability of the safety injection system in the prior art is low. Summary of the invention

[0004] The embodiments of the present invention provide a safety injection system and a nuclear power plant to solve the problem of low reliability of the safety injection system in the prior art.

[0005] In order to solve the above-mentioned technical problems, the present invention is achieved as follows:

[0006] In a first aspect, an embodiment of the present invention provides a safety injection system, which is applied to a nuclear power plant, wherein the nuclear power plant includes a reactor pressure vessel, N steam generators and N hot pipe segments, each steam generator is connected to the reactor pressure vessel through a hot pipe segment, the safety injection system includes N safety injection units, N direct injection pipelines and N hot segment injection pipelines, N is a positive integer, and N is greater than 1, each safety injection unit is connected to the reactor pressure vessel through a direct injection pipeline and a hot segment injection pipeline, and the safety injection unit includes:

[0007] A safety injection box, the safety injection box is connected to the reactor pressure vessel through a direct injection pipeline;

[0008] The injection pump comprises a first outlet pipe and a second outlet pipe, wherein the first outlet pipe is connected to the reactor pressure vessel through the direct injection pipeline, and the second outlet pipe is connected to the hot pipe section through the hot section injection pipeline.

[0009] Optionally, the safety injection pump further includes a third outlet pipe, and the safety injection unit further includes a return pipeline, one end of the return pipeline is connected to the third outlet pipe, and the other end of the return pipeline is connected to the water tank.

[0010] Optionally, the nuclear power plant further includes N power supply systems, each safety injection unit is connected to a power supply system, the power supply system is used to provide power supply for the safety injection pump, and the N power supply systems are independent of each other.

[0011] Optionally, the safety injection system further includes a water tank, the safety injection pump further includes a first inlet pipe, and the first inlet pipes of the safety injection pumps of the N safety injection units are all connected to the water tank.

[0012] Optionally, the safety injection pump further includes a fourth outlet pipe, and the safety injection unit further includes a pH value adjusting device, the inlet end of the pH value adjusting device is connected to the fourth outlet pipe, and the outlet end of the pH value adjusting device is connected to a water tank.

[0013] Optionally, the inlet and outlet of the pH adjusting device are both provided with isolation valves.

[0014] Optionally, when the pressure of water in the reactor pressure vessel is lower than a first preset pressure, the injection pump is used to inject a first coolant into the reactor pressure vessel; and / or, when the pressure of water in the reactor pressure vessel is lower than the pressure in the injection tank, the injection tank is used to inject a second coolant into the reactor pressure vessel.

[0015] Optionally, the direct injection pipeline, the hot section injection pipeline and the return pipeline are all provided with isolation valves and check valves.

[0016] Optionally, the value of N is 2.

[0017] In a second aspect, an embodiment of the present invention provides a nuclear power plant, comprising a reactor pressure vessel, N steam generators and N heat pipe segments, each steam generator being connected to the reactor pressure vessel via a heat pipe segment, and the nuclear power plant also comprising the safety injection system described in the first aspect.

[0018] In the embodiment of the present invention, coolant is injected into the reactor pressure vessel through the direct injection pipeline and the hot section injection pipeline, thereby increasing the flow share of the coolant entering the reactor pressure vessel in the event of a cold pipe section rupture accident; and the injection of coolant is achieved through multiple safety injection units, thereby avoiding the situation where the safety injection system becomes unavailable when a safety injection box or a safety injection pump of a single safety injection unit becomes unavailable. The safety injection system provided by the embodiment of the present invention has high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0020] Figure 1 It is a structural schematic diagram of a safety injection system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] See also Figure 1 , Figure 1 is a schematic diagram of the structure of a safety injection system provided in an embodiment of the present invention, wherein the safety injection system is applied to a nuclear power plant, wherein the nuclear power plant comprises a reactor pressure vessel 1, N steam generators 2 and N heat pipe segments 8, wherein each steam generator 2 is connected to the reactor pressure vessel 1 via a heat pipe segment 8, such as Figure 1 As shown, the safety injection system includes N safety injection units, N direct injection pipelines 7 and N hot section injection pipelines 9, N is a positive integer, and N is greater than 1, each safety injection unit is connected to the reactor pressure vessel 1 through a direct injection pipeline 7 and a hot section injection pipeline 9, and the safety injection unit includes:

[0023] A safety injection box 4, wherein the safety injection box 4 is connected to the reactor pressure vessel 1 via a direct injection pipeline 7;

[0024] The injection pump 3 includes a first outlet pipe and a second outlet pipe, wherein the first outlet pipe is connected to the reactor pressure vessel 1 through the direct injection pipeline 7, and the second outlet pipe is connected to the hot pipe section 8 through the hot section injection pipeline 9.

[0025] The steam generator 2 is used to generate steam through the heat generated by the reactor pressure vessel 1, and then the generated steam drives the steam turbine generator to generate electricity. The heat generated by the reactor core in the reactor pressure vessel 1 heats the water in the reactor pressure vessel 1, and the high-temperature water in the reactor pressure vessel 1 enters the steam generator 2, heats the feed water on the secondary side in the steam generator 2, and generates steam, thereby driving the steam turbine generator to generate electricity. At the same time, the high-temperature water in the reactor pressure vessel 1 is cooled and returned to the reactor pressure vessel 1 through the cold pipe section. The hot pipe section 8 is used to connect the steam generator 2 with the reactor pressure vessel 1. The reactor pressure vessel 1 is also connected to the main pump through the cold pipe section, and the main pump is used to drive the coolant to circulate in the coolant system of the reactor pressure vessel 1. Preferably, the direct injection pipeline 7 can be arranged near the cold pipe section.

[0026] Among them, each safety injection unit is connected to the reactor pressure vessel 1 through a direct injection pipeline 7, and the direct injection pipelines 7 connecting the N safety injection units to the reactor pressure vessel 1 are different, and each safety injection unit is also connected to the reactor pressure vessel 1 through a hot pipe section 8, and the hot pipe sections 8 connecting the N safety injection units to the reactor pressure vessel 1 are different.

[0027] Among them, the injection tank 4 and the injection pump 3 are both used to provide coolant for the reactor pressure vessel 1. Preferably, the coolant is water, preferably boron-containing water. The outlet pipe of the injection tank 4 is connected to the direct injection pipeline 7. The outlet pipe of the injection tank 4 can be provided with an isolation valve 11 and a check valve 12, and the isolation valve 11 is in an open state. The top of the injection tank 4 is filled with nitrogen of a preset pressure value, and the nitrogen is suspended above the coolant. The preset pressure value can be 2MPa, or 4MPa, or 6MPa, etc. When the nuclear power plant is working normally, the nitrogen pressure value in the injection tank 4 is lower than the pressure value of the water in the reactor pressure vessel 1, and the injection tank 4 is in a closed state and will not output coolant to the reactor pressure vessel 1. When an accident occurs in the nuclear power plant, the pressure value in the reactor pressure vessel 1 drops and is lower than the nitrogen pressure value in the injection tank 4, the coolant in the injection tank 4 is injected into the reactor pressure vessel 1 through the direct injection pipeline 7.

[0028] In practical applications, if an accident occurs in a nuclear power plant, such as a LOCA (Loss of Coolant Accident) accident, a SGTR (Steam Generator Tube Rupture) accident, etc., a safety injection signal will be triggered. After receiving the safety injection signal, the safety injection pump 3 starts to extract coolant from the water tank 5. The safety injection pump 3 injects coolant into the reactor pressure vessel 1 through the direct injection pipeline 7, and injects coolant into the reactor pressure vessel 1 through the hot section injection pipeline 9. When the safety injection pump 3 reduces the pressure value in the reactor pressure vessel 1 to below the preset pressure value of the safety injection tank 4, the safety injection tank 4 starts, and the coolant in the safety injection tank 4 is injected into the reactor pressure vessel 1 through the direct injection pipeline 7. When no accident occurs in the nuclear power plant, the safety injection system will not start and is in a standby state.

[0029] For example, the injection tank 4 is started when the pressure value of the water in the reactor pressure vessel 1 is lower than 4MPa. When the pressure value of the water in the reactor pressure vessel 1 is 10MPa, the injection pump 3 is started, and the pressure value of the water in the reactor pressure vessel 1 is reduced from 10MPa to below 4MPa through the injection pump 3. At this time, the injection tank 4 is started, and the injection pump 3 and the injection tank 4 simultaneously inject coolant into the core of the reactor pressure vessel 1 to ensure that the core is better cooled.

[0030] It should be noted that in the prior art, the safety injection system injects coolant into the reactor pressure vessel 1 through the cold section injection pipeline. When the cold pipe section breaks, the coolant cannot be injected into the reactor pressure vessel 1 through the cold section injection pipeline via the cold pipe section, so that in the cold pipe section break accident, the corresponding safety injection unit is unavailable. Injecting coolant into the reactor pressure vessel 1 through the cold section injection pipeline and the hot section injection pipeline 9 will cause the flow share of the coolant injected into the reactor pressure vessel 1 by the safety injection system to be reduced in the cold pipe section break accident. In the embodiment of the present invention, coolant is injected into the reactor pressure vessel 1 through the direct injection pipeline 7 and the hot section injection pipeline 9, and in the cold pipe section break accident, the flow share of the coolant entering the reactor pressure vessel 1 is increased; and the injection of coolant is achieved through multiple safety injection units, which avoids the situation where the safety injection system is unavailable when the safety injection box 4 or the safety injection pump 3 of a single safety injection unit is unavailable, and the safety injection system provided by the embodiment of the present invention has high reliability.

[0031] Optionally, the safety injection pump 3 further includes a third outlet pipe, and the safety injection unit further includes a return pipeline 10 , one end of the return pipeline 10 is connected to the third outlet pipe, and the other end of the return pipeline 10 is connected to the water tank 5 .

[0032] The return line 10 may be a small flow return line 10, and the flow rate of the liquid flowing through the return line 10 is small. When the injection pump 3 is started or stopped, the remaining coolant in the pipeline flows back to the water tank 5 through the return line 10, which can protect the injection pump 3.

[0033] Optionally, the nuclear power plant further includes N power supply systems, each safety injection unit is connected to a power supply system, the power supply system is used to provide power supply for the safety injection pump 3, and the N power supply systems are independent of each other. When one of the power supply systems fails, the other N-1 power supply systems can still work normally, which can further improve the reliability of the safety injection system.

[0034] Optionally, the safety injection system further includes a water tank 5 , and the safety injection pump 3 further includes a first inlet pipe, and the first inlet pipes of the safety injection pumps 3 of the N safety injection units are all connected to the water tank 5 .

[0035] The water tank 5 can provide coolant for the injection pump 3, and the injection pumps 3 of the N safety injection units all draw coolant from the water tank 5. An isolation valve 11 can be provided on the first inlet pipe, and the isolation valve 11 can be in a normally open state to keep the first inlet pipe full of coolant, so that the injection pump 3 can quickly enter the working state.

[0036] Optionally, the safety injection pump 3 further includes a fourth outlet pipe, and the safety injection unit further includes a pH value adjusting device 6 , the inlet end of the pH value adjusting device 6 is connected to the fourth outlet pipe, and the outlet end of the pH value adjusting device 6 is connected to the water tank 5 .

[0037] Among them, the structural form of the pH value adjusting device 6 is not limited, and it can be a mesh structure, or a perforated structure, etc. The expression form of the pH value adjusting agent in the pH value adjusting device 6 is not limited, and it can be sodium hydroxide, or trisodium phosphate, etc. As a specific embodiment, the coolant is water. When a loss of coolant accident occurs in a nuclear power plant, the radioactive water in the reactor pressure vessel 1 enters the containment and flows into the water tank 5 through a series of reflux channels. The water in the water tank 5 is used as cooling water for nuclear power plant accidents, and the pH value of the water needs to be controlled. Therefore, it is necessary to use the pH value adjusting device 6 to complete the control of the pH value of the water in the water tank 5, control the retention of radioactive nuclides in the water tank 5, and prevent corrosion of the equipment in the containment. At the same time, the pH value adjusting device 6 is arranged in parallel with the return pipeline 10, and the water in the injection pump 3 flows into the water tank 5 from the fourth outlet pipe through the pH value adjusting device 6, and there is no need to add additional active equipment such as pumps, and the configuration is simple.

[0038] The pH value of the water in the water tank 5 is controlled by the pH value adjusting device 6, so that the equipment in the containment can be protected from corrosion.

[0039] Optionally, an isolation valve 11 is provided at both the inlet and outlet of the pH value adjusting device 6 .

[0040] Wherein, when the safety injection system is not started, the isolation valves 11 on the inlet and outlet of the pH value adjusting device 6 are both in a closed state. When a nuclear power plant accident occurs, the safety injection system is started, and in the later stage of the accident, the isolation valves 11 on the inlet and outlet of the pH value adjusting device 6 are both in an open state to complete the control of the pH value of the liquid in the water tank 5.

[0041] The opening and closing of the pH value adjusting device 6 is controlled by the isolation valve 11, which has a simple structure and is relatively convenient to implement.

[0042] Optionally, when the pressure of water in the reactor pressure vessel 1 is lower than a first preset pressure, the injection pump 3 is used to inject a first coolant into the reactor pressure vessel 1; and / or, when the pressure of water in the reactor pressure vessel 1 is lower than the pressure in the injection tank 4, the injection tank 4 is used to inject a second coolant into the reactor pressure vessel 1.

[0043] Among them, the first preset pressure is greater than the second preset pressure, and the first preset pressure can be 10Mpa, or can be 12Mpa, etc. The second preset pressure can be 4Mpa, or can be 6Mpa, or can be, etc. The first coolant and the second coolant can be the same or different. As a specific implementation, when the nuclear power plant is operating normally, the pressure value of the water in the reactor pressure vessel 1 is higher than 15MPa. When a loss of coolant accident occurs in the nuclear power plant, and the pressure value of the water in the reactor pressure vessel 1 is lower than 10MPa, the injection pump 3 is started, and the pressure value of the water in the reactor pressure vessel 1 is reduced from 10MPa to below 4MPa through the injection pump 3. At this time, the injection tank 4 is started, and the injection pump 3 and the injection tank 4 simultaneously inject coolant into the core of the reactor pressure vessel 1 to ensure that the core is better cooled.

[0044] In an embodiment of the present invention, when the pressure of water in the reactor pressure vessel 1 is lower than a first preset pressure, the injection pump 3 is used to inject a first coolant into the reactor pressure vessel 1; and / or, when the pressure of water in the reactor pressure vessel 1 is lower than the pressure in the injection tank 4, the injection tank 4 is used to inject a second coolant into the reactor pressure vessel 1. The safety injection system of the embodiment of the present invention can better achieve core cooling of the reactor pressure vessel 1.

[0045] Optionally, the direct injection pipeline 7 , the hot section injection pipeline 9 and the return pipeline 10 are all provided with an isolation valve 11 and a check valve 12 .

[0046] Among them, the flow rate of the coolant flowing through the direct injection pipeline 7 is relatively large, and the isolation valve 11 on the direct injection pipeline 7 is in an open state, so that when the safety injection system needs to be put into operation, the injection pump 3 can quickly inject a large amount of coolant into the reactor pressure vessel 1 through the direct injection pipeline 7. When the safety injection system needs maintenance and inspection, the isolation valve 11 on the direct injection pipeline 7 is in a closed state, which is convenient for maintenance and inspection. When the safety injection system is in a standby state, the isolation valve 11 on the hot section injection pipeline 9 is in a closed state, and when the safety injection system is started, the isolation valve 11 on the hot section injection pipeline 9 is in an open state. The isolation valve 11 on the return pipeline 10 is in an open state, so that the injection pump 3 is always in a standby state to ensure that the injection pump 3 starts normally and effectively control the closing pressure head of the injection pump 3.

[0047] Optionally, the value of N is 2.

[0048] Among them, Figure 1 As shown, the safety injection system includes a first safety injection unit 13 and a second safety injection unit 14 .

[0049] The embodiment of the present invention further provides a nuclear power plant, which includes a reactor pressure vessel 1, N steam generators 2 and N heat pipe segments 8, each steam generator 2 is connected to the reactor pressure vessel 1 through a heat pipe segment 8, and the nuclear power plant also includes the safety injection system of the above embodiment. The specific structure of the safety injection system has been described in detail in the above embodiment, and can achieve the same beneficial effects, so it will not be repeated in this embodiment.

[0050] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0051] In the description of the present invention, it should be understood that the terms "longitudinal", "radial", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0052] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "setting" and "connection" 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 directly connected or indirectly connected through an intermediate medium. Fixed connection can be common technical solutions such as welding, threaded connection and tightening. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A safety injection system, applied to a nuclear power plant, characterized in that: The nuclear power plant includes a reactor pressure vessel, N steam generators and N hot pipe segments, each steam generator is connected to the reactor pressure vessel through a hot pipe segment, the safety injection system includes N safety injection units, N direct injection pipelines and N hot segment injection pipelines, N is a positive integer, and N is greater than 1, each safety injection unit is connected to the reactor pressure vessel through a direct injection pipeline and a hot segment injection pipeline, and the safety injection unit includes: A safety injection box, the safety injection box is connected to the reactor pressure vessel through a direct injection pipeline; An injection pump, the injection pump comprising a first outlet pipe and a second outlet pipe, the first outlet pipe is connected to the reactor pressure vessel through the direct injection pipeline, and the second outlet pipe is connected to the hot pipe section through the hot section injection pipeline; The safety injection pump further includes a fourth outlet pipe, and the safety injection unit further includes a pH value adjusting device, the inlet end of the pH value adjusting device is connected to the fourth outlet pipe, and the outlet end of the pH value adjusting device is connected to the water tank; The inlet and outlet ends of the pH value adjusting device are both provided with isolation valves; When the safety injection system is not activated, the isolation valves on the inlet and outlet of the pH value adjusting device are both in a closed state; when a nuclear power plant accident occurs, the safety injection system is activated, and in the later stage of the accident, the isolation valves on the inlet and outlet of the pH value adjusting device are both in an open state to complete the control of the pH value of the liquid in the water tank; The safety injection pump further includes a third outlet pipe, and the safety injection unit further includes a return pipeline, one end of the return pipeline is connected to the third outlet pipe, and the other end of the return pipeline is connected to the water tank; The direct injection pipeline, the hot section injection pipeline and the return pipeline are all provided with isolation valves and check valves; Wherein, when the safety injection system needs to be put into operation, the isolation valve on the direct injection pipeline is in an open state; When the safety injection system needs maintenance and inspection, the isolation valve on the direct injection pipeline is in a closed state; When the safety injection system is in a standby state, the isolation valve on the hot section injection pipeline is in a closed state; When the safety injection system is started, the isolation valve on the hot section injection pipeline is in an open state, and the isolation valve on the return pipeline is in an open state.

2. The safety injection system according to claim 1, characterized in that: The nuclear power plant further includes N power supply systems, each safety injection unit is connected to a power supply system, the power supply system is used to provide power supply for the safety injection pump, and the N power supply systems are independent of each other.

3. The safety injection system according to claim 1, characterized in that: The safety injection system further includes a water tank, and the safety injection pump further includes a first inlet pipe. The first inlet pipes of the safety injection pumps of the N safety injection units are all connected to the water tank.

4. The safety injection system according to claim 1, characterized in that: When the pressure of water in the reactor pressure vessel is lower than a first preset pressure, the injection pump is used to inject a first coolant into the reactor pressure vessel; and / or, when the pressure of water in the reactor pressure vessel is lower than the pressure in the injection tank, the injection tank is used to inject a second coolant into the reactor pressure vessel.

5. The safety injection system according to claim 1, characterized in that: The value of N is 2.

6. A nuclear power plant, characterized in that: The nuclear power plant comprises a reactor pressure vessel, N steam generators and N heat pipe segments, each steam generator is connected to the reactor pressure vessel via a heat pipe segment, and the nuclear power plant further comprises a safety injection system as described in any one of claims 1-5.

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