Pool type reactor safety management system and method

Abstract

A pool type reactor safety management system comprises a reactor shut-down device, a passive residual heat removal device, a main circulation device, an auxiliary circulation device and a passive circulation device, and the reactor shut-down device is used for realizing reactor shut-down under accident conditions; the passive residual heat removal device forms natural circulation of the reactor water pool and the external hot trap; the main circulating device provides a circulating pipeline and drives cooling water to circulate under a normal working condition; the auxiliary circulating device comprises an auxiliary circulating pump connected to the main circulating pump in parallel; and the passive circulating device comprises a natural circulating valve arranged in the lower cavity of the reactor. The system can effectively avoid overheating of the cooling water under the accident working condition, so that the flowing direction of the cooling water is quickly switched from forced convection under the normal working condition to natural convection under the accident working condition, the flowing stagnation is prevented, and the safety and the reliability of the pool type reactor are effectively improved. The invention also provides a pool type reactor safety management method.

Description

Technical Field

[0001] The invention belongs to the field of nuclear power, and in particular relates to a pool-type reactor safety management system and method. Background Art

[0002] A pool reactor is a small reactor that is placed in a large water pool. It has the advantages of simple structure and flexible use. It has been widely used in the fields of physics and engineering experiments, and also has good prospects in the field of nuclear energy heating applications. Due to the differences in structure and volume, the dedicated safety system of the pool reactor is different from that of a conventional pressurized water reactor. It mainly relies on an active system supported by external power. In addition, pool reactors are usually used for scientific research or experiments, and the manpower and external support are relatively limited compared to conventional nuclear power plants. The safety margin of the dedicated safety system of the existing pool reactor still has room for optimization and improvement. Therefore, it is of positive significance to provide a safety management system that can effectively improve the safety and reliability of the pool reactor based on the structural characteristics of the pool reactor. Summary of the invention

[0003] The purpose of the present invention is to provide a pool-type reactor safety management system to improve the safety of the pool-type reactor. The present invention also provides a pool-type reactor safety management method.

[0004] According to an embodiment of one aspect of the present invention, there is provided a pool-type reactor safety management system, which includes: a shutdown device, a passive residual heat removal device, a main circulation device, an auxiliary circulation device and a passive circulation device. Among them, the shutdown device is used to intervene in the reactor core under accident conditions to achieve shutdown; the passive residual heat removal device includes a pool heat exchanger, an external heat exchanger and an external heat sink, the pool heat exchanger is arranged in the reactor water pool, the external heat exchanger is arranged in the external heat sink, the pool heat exchanger is connected to the external heat exchanger to form a circulation loop, and when the temperature of the pool heat exchanger is higher than that of the external heat exchanger, it forms a natural circulation; the main circulation device includes a main circulation pump and a circulation pipeline, the main circulation pump drives the cooling water circulation under normal conditions; the two ends of the circulation pipeline are respectively connected to the lower chamber of the reactor, A siphon destruction hole is provided at a position upstream of the lower chamber of the reactor and higher than the reactor core; an isolation device is provided upstream of the lower chamber of the reactor for the circulation pipeline; when the isolation device is turned off, cooling water in the circulation pipeline flows into the reactor water pool through the isolation device; when the isolation device is opened, at least part of the cooling water in the circulation pipeline flows into the lower chamber of the reactor through the isolation device; the auxiliary circulation device comprises an auxiliary circulation pump, which is connected in parallel to the main circulation pump; and the passive circulation device comprises a natural circulation valve arranged in the lower chamber of the reactor.

[0005] Under accident conditions, the system can combine active safety management devices with passive safety management devices to achieve shutdown and core cooling, so that the flow direction of cooling water in the pool can be quickly switched from top to bottom under normal conditions to bottom to top under accident conditions, avoiding cooling water flow stagnation when the main circulation pump is shut down, thereby improving reactor safety.

[0006] Furthermore, in some embodiments, the shutdown device includes a control rod assembly and / or a heavy water tank, the control rod assembly includes a neutron absorber control rod, and the control rod assembly is capable of inserting the neutron absorber control rod into the core; the heavy water tank stores heavy water, and the heavy water tank is capable of injecting the heavy water into the core in a passive form.

[0007] Furthermore, in some embodiments, the external heat well is also provided with an external heat well cooling device for reducing the temperature of the external heat well.

[0008] Further, in some embodiments, the isolation device includes a main system inlet pipe ejector and an ejector isolation valve; the main system inlet pipe ejector includes a nozzle, an intake chamber, a throat and a diffuser. The nozzle is connected to the upstream circulation pipeline; the intake chamber is in a trumpet shape with an enlarged diameter at one end facing the nozzle and connected to the reactor water pool, and the other end is connected to the throat; one end of the diffuser is connected to the throat, and the other end has a gradually enlarged diameter and is connected to the ejector isolation valve. The main system inlet pipe ejector is connected to the lower chamber of the reactor through the ejector isolation valve. When the ejector isolation valve is closed, the cooling water in the circulation pipeline flows back into the reactor water pool through the main system inlet pipe ejector; when the ejector isolation valve is opened, at least part of the cooling water in the circulation pipeline and part of the cooling water in the reactor water pool flow into the lower chamber of the reactor through the main system inlet pipe ejector.

[0009] The main system inlet pipe ejector can introduce cooling water from the reactor pool into the lower chamber of the reactor, thereby improving the circulation efficiency of the cooling water.

[0010] Furthermore, in some embodiments, the drainage ratio of the main system inlet pipe ejector is 1.05-1.2.

[0011] Furthermore, in some embodiments, the circulation pipeline is also provided with a main system outlet pipe injector downstream of the lower chamber of the reactor, and the main system outlet pipe injector includes a nozzle, a suction chamber, a throat and a diffuser; the nozzle is connected to the upstream circulation pipeline; the suction chamber is in a trumpet shape with an enlarged diameter at one end facing the nozzle and is connected to the reactor water pool, and the other end is connected to the throat; one end of the diffuser is connected to the throat, and the other end has a gradually enlarged diameter and is connected to the circulation pipeline.

[0012] Furthermore, in some embodiments, the system also includes a spray system, which includes a passive water storage tank, and the passive water storage tank can spray cooling water to the plant building where the reactor is located under accident conditions.

[0013] Furthermore, in some embodiments, the system also includes a filtering and exhausting system, which is used to filter radioactive pollutants and discharge the gas in the plant where the reactor is located.

[0014] Furthermore, in some embodiments, the pool-type reactor is equipped with a high-temperature and high-pressure irradiation pipeline, and the pool-type reactor safety management system includes a pressure compartment, and the high-temperature and high-pressure irradiation pipeline is enclosed in the pressure compartment, and the wall of the pressure compartment is provided with a heat conducting plate to extract the heat in the pressure compartment; the pressure compartment also includes a pressure suppression tube, one end of the pressure suppression tube is connected to the pressure compartment and the other end is immersed in the cooling water of the reactor water pool, and is provided with a check valve and a bubbler.

[0015] Furthermore, in some embodiments, the pressure-bearing compartment is also provided with a bursting disk, and when the bursting disk explodes, the pressure-bearing compartment is depressurized.

[0016] According to another embodiment of the present invention, a pool-type reactor safety management method is provided. The method adopts the pool-type reactor safety management system provided in any of the above embodiments and comprises the following steps: in an accident condition,

[0017] Step a): starting the shutdown device to shut down the reactor;

[0018] Step b): using the auxiliary circulation pump to force cooling water to circulate until the core decay heat is reduced to below a first threshold value of the rated power;

[0019] Step c): opening the isolation device, shutting off the downstream pipeline of the lower chamber of the reactor, and allowing the auxiliary circulation pump to drive cooling water to flow into the lower chamber of the reactor through the isolation device and out of the upper part of the reactor, so as to achieve the reversal of the flow direction of the core cooling water;

[0020] Step d): after the flow direction of the core cooling water is reversed, the auxiliary circulation pump is turned off to perform natural circulation;

[0021] Step e): when the core decay heat decreases below a second threshold value of the rated power, opening the natural circulation valve.

[0022] Furthermore, in some embodiments, the first threshold is 2% of the rated power of the core; and the second threshold is 1% of the rated power of the core. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the structure of a pool-type reactor safety management system in one embodiment;

[0024] Figure 2 It is a schematic structural diagram of a pool-type reactor safety management system in another embodiment;

[0025] Figure 3 Schematic diagram of the ejector structure in one embodiment.

[0026] Meaning of the reference numerals: 10 - reactor core; 11 - reactor lower chamber; 111 - main system outlet pipe; 112 - main system inlet pipe; 12 - delay water tank; 13 - main circulation pump; 14 - auxiliary circulation pump; 15 - main circulation pump isolation valve; 16 - auxiliary circulation pump isolation valve; 17 - main circulation pump rear check valve; 18 - auxiliary circulation pump rear check valve; 19 - main heat exchanger; 20 - irradiation circuit pressure vessel; 21 - irradiation circuit pressurizer; 22 - irradiation circuit main heat exchanger device; 23- irradiation loop circulation pump; 24- irradiation loop hot pipe section; 241- irradiation loop hot pipe section injection isolation valve; 25- irradiation loop transition section; 26- irradiation loop cold pipe section; 261- irradiation loop cold pipe section injection isolation valve; 27- irradiation loop emergency residual heat discharge heat exchanger; 28- irradiation loop pressure storage injection box; 29- irradiation loop injection pump; 30- reactor pool; 31- siphon destruction valve; 32- hump pipe section; 33- siphon destruction valve outlet pipe end; 34- siphon Suction destruction hole; 35-main system inlet pipe ejector; 351-nozzle; 352-suction chamber; 353-throat; 354-diffuser; 36-ejector isolation valve; 37-natural circulation valve; 38-reactor lower chamber outlet isolation valve; 39-main system outlet ejector pipe; 40-external heat exchanger; 41-waste outlet pipeline isolation valve; 42-waste inlet pipeline isolation valve; 43-waste outlet pipeline; 44-waste inlet pipeline; 45-water pool heat exchanger; 50-control Rod assembly; 51-heavy water tank; 52-heavy water discharge isolation valve; 53-heavy water discharge tank; 60-pressure compartment; 61-compartment spray water tank; 62-compartment spray isolation valve; 63-compartment spray head; 64-compartment pressure suppression pipe check valve; 65-bubbler; 66-bursting disk; 70-reactor building; 71-building spray water tank; 72-building spray isolation valve; 73-building spray head; 74-building active filtering exhaust; 80-external heat sink; 81-external heat sink cooling device.

[0027] The purpose of the above drawings is to explain the present invention in detail so that those skilled in the art can understand the technical concept of the present invention, but it is not intended to limit the present invention. For the sake of simplicity, the above drawings only schematically illustrate the structures related to the technical features of the present invention, and do not strictly follow the actual proportions to draw the complete structure and all details. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0029] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The phrase appearing in various locations in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive independent or alternative embodiments. Those skilled in the art should be able to understand that the embodiments herein may be combined with other embodiments without causing structural conflicts.

[0030] In the description of this article, unless otherwise clearly specified and limited, the technical terms "installed", "connected", "connected" and the like should be understood in a broad sense, for example, it can be a mechanical structure connection, or a signal connection relationship; it can be a movable connection, or a fixed connection or integration. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of this application can be understood according to specific circumstances.

[0031] In the description of this document, terms indicating orientation or positional relationships, such as "up", "down", "left", "right", "horizontal", "vertical", "height", "length", and "width", are intended to accurately describe the embodiments and simplify the description, but are not intended to limit the parts or structures involved to have a specific orientation, be installed or operate in a specific orientation, and should not be construed as a limitation on the embodiments in this document.

[0032] In the description of this article, the terms "first", "second" and the like are only used to distinguish different objects, and cannot be understood as indicating relative importance or limiting the quantity, specific order or primary and secondary relationship of the described technical features. In the description of this article, the meaning of "plurality" is at least two.

[0033] The pool-type reactor places the core in a large water pool. It has the advantages of simple structure and flexible use, and can be used to carry out various physical or engineering experiments. The loop of the pool-type reactor is connected to the water pool where it is located. Under normal operating conditions, the heat of the core is exported to the heat exchanger by the loop, thereby achieving heat supply, gas supply or generating steam for power generation. In some application scenarios, in order to use the radiation generated by the reactor core to carry out research work such as fuel and material irradiation testing, the pool-type reactor will also be equipped with a high-temperature and high-pressure irradiation loop, and the fuel or material to be tested will be placed inside the loop, and the heat in the loop will be exported through a special cooling system.

[0034] Under accident conditions, when the main heat exchanger of the pool-type reactor is unavailable, the residual heat of the core cannot be discharged by conventional means; if a main system pressure boundary breach occurs, a large amount of cooling water of the reactor will be lost, which may cause the exposed core heat transfer to deteriorate; in addition, if there is a lack of means to remove heat after the accident, the reactor building may continue to increase in pressure, especially in reactors equipped with high-temperature and high-pressure irradiation circuits. The rupture of the high-temperature and high-pressure irradiation circuit will cause further temperature and pressure increases, and may even cause the reactor building to fail due to overpressure and damage the radioactive barrier.

[0035] However, due to the limitation of reactor size and actual conditions, the existing pool-type reactors’ dedicated safety systems all adopt active systems, which rely on external power. Once the external power is lost, the active safety systems will not be able to perform their functions normally. Pool-type reactors are usually used for scientific research or experiments, and the manpower and external support are not as sufficient as those of nuclear power plants. On the other hand, after an accident, when the main circulation pump stops, the pool-type reactor needs to use the natural circulation of cooling water in the pool to remove the heat from the core. However, under normal operating conditions, the cooling water in the core flows from top to bottom, while under natural circulation, the cooling water needs to flow from bottom to top. During the reversal of the cooling water flow direction, there may be a state of flow stagnation, resulting in a short-term deterioration of the core heat transfer. At the same time, pool-type reactors usually do not have the reinforced concrete structure or steel structure containment of pressurized water reactor nuclear power plants, and their pressure bearing capacity is weak, and their ability to withstand the temperature and pressure rise in the plant is limited.

[0036] In order to solve the above problems, an embodiment of one aspect of the present invention provides a pool-type reactor safety management system.

[0037] In a preferred embodiment, Figure 1 As shown, the reactor core 10 of the pool-type reactor is placed in the reactor water pool 30, and the reactor lower chamber 11 is formed below the reactor core 10. The reactor lower chamber 11 is provided with a reactor lower chamber outlet pipe isolation valve 38 connected to the main system outlet pipe 111, and further connected to the delay water tank 12. The delay water tank 12 is arranged outside the reactor water pool 30, and is connected to the main circulation pump 13 through a pipeline. The downstream pipeline of the main circulation pump 13 is provided with a main circulation pump rear check valve 17 and a main circulation pump isolation valve 15, and is connected to the inlet of the main heat exchanger 19. The outlet of the main heat exchanger 19 is connected to the main system inlet pipe injector 35 through the main system inlet pipe 112, and a normally closed injector isolation valve 36 is provided between the main system inlet pipe injector 35 and the reactor lower chamber 11. The main circulation pump and its upstream and downstream circulation pipelines constitute the main circulation device of the safety management system, which is used to drive the cooling water to flow under normal working conditions.

[0038] Between the delay water tank 12 and the main heat exchanger 19, an auxiliary circulation pump 14 is connected in parallel with the main circulation pump. The auxiliary circulation pump 14 is a safety-grade device, and its outlet is provided with an auxiliary circulation pump rear check valve and a normally open auxiliary mixed environmental protection isolation valve 16. The auxiliary circulation pump 14 is an auxiliary circulation device, which is used to intervene and maintain the circulation of cooling water after the main circulation pump 13 is shut down under accident conditions.

[0039] A control rod assembly 50 is arranged above the reactor core 10. The control rod assembly 50 includes a neutron absorber control rod. The control rod assembly 50 is inserted into the reactor core 10 from top to bottom to realize the reactor shutdown. A heavy water tank 51 is arranged outside the reactor core 10. The heavy water tank 51 stores heavy water. The heavy water tank 51 is configured as a passive device and is connected to a heavy water discharge tank 53 through a heavy water discharge isolation valve 52. Heavy water as a neutron moderator can be injected into the reactor core 10 in a passive manner, which can also play a role in reducing the reaction power or even shutting down the reactor. The passive method can be gas pressure drive or gravity drive. The control rod assembly 50 and the heavy water tank 51 constitute a shutdown device, which is used to perform shutdown under accident conditions to prevent the accident from worsening.

[0040] A large amount of cooling water is stored in the reactor pool 30, and the water depth is usually 6m-12m. The lower chamber 11 of the reactor immersed in the bottom of the reactor pool 30 is provided with a natural circulation valve 37. The natural circulation valve 37 connects the lower chamber 11 of the reactor with the reactor pool 30 to allow the cooling water to flow between the reactor pool 30 and the lower chamber 11 of the reactor. Under normal conditions, the natural circulation valve 37 remains normally closed. The natural circulation valve 37 is a passive circulation device, which is used to assist the cooling water in the reactor pool 30 to flow in a natural circulation manner to take away the heat of the reactor core 10 under accident conditions.

[0041] A water pool heat exchanger 45 is also provided in the reactor water pool 30. The water pool heat exchanger 45 is connected to an external heat exchanger 40 provided outside the reactor building 70 through a waste discharge outlet pipeline 43 and a waste discharge inlet pipeline 44. One end of the waste discharge outlet pipeline 43 is connected to the outlet of the external heat exchanger 40, and the other end is connected to the inlet of the water pool heat exchanger 45. A waste discharge outlet pipeline isolation valve 41 is provided on the waste discharge outlet pipeline 43; one end of the waste discharge inlet pipeline 44 is connected to the inlet of the external heat exchanger 40, and the other end is connected to the outlet of the water pool heat exchanger 45. A waste discharge inlet pipeline isolation valve 42 is provided on the waste discharge inlet pipeline 44. The external heat exchanger 40 is placed in an external heat well 80 outside the reactor building 70. In some embodiments, the external heat well 80 is set as a water reservoir. In a preferred embodiment, the heat storage capacity of the external heat well 80 can meet the requirements of core waste heat discharge for at least 30 days. Under accident conditions, the temperature of the reactor water pool 30 rises, and the temperature of the water pool heat exchanger 45 is higher than that of the external heat exchanger 40, and a circulation loop is formed through the waste discharge inlet pipeline 44 and the waste discharge outlet pipeline 43, and natural circulation is performed. In a further preferred embodiment, the external heat sink 80 is further provided with an external heat sink cooling device 81 to further improve the cooling capacity of the external heat sink 80 for the reactor water pool 30 heat discharge.

[0042] A main system outlet pipe injector 39 is also provided on the main system outlet pipe 111. The main system outlet pipe injector 39 is arranged between the reactor lower chamber outlet isolation valve 38 and the delay water tank 12. Its position is higher than the top of the reactor core 10 and not higher than the highest point of the main system outlet pipe 111.

[0043] The structure of the main system outlet pipe injector 39 is basically the same as that of the main system inlet pipe injector 35. Figure 3 The structure of the ejector is described. The ejector includes a nozzle 351, a suction chamber 352, a throat 353 and a diffuser 354. The nozzle 351 is connected to the upstream circulation pipeline, the suction chamber 352 is in a trumpet shape with an enlarged diameter at one end facing the nozzle 351 and connected to the reactor water pool 30, and the other end is connected to the throat 353; the diffuser 354 is connected to the throat at one end, and the diameter of the other end gradually increases and is connected to the downstream circulation pipeline through the downstream pipeline. Cooling water is ejected from the nozzle 351 and enters the suction chamber 352; while receiving the cooling water ejected from the nozzle 351, the suction chamber 352 also inhales part of the cooling water from the reactor water pool 30, and the cooling water enters the diffuser 354 through the throat 353 and then flows out of the ejector. Relative to the cooling water flow ejected from the nozzle 351, the diffuser 354 can output a higher cooling water flow, thereby achieving the effect of accelerating the circulation of cooling water. In a preferred embodiment, by designing the ejector structure, the drainage ratio of the ejector can reach 1.05-1.2.

[0044] The main system inlet pipe 112 is inserted into the cooling water of the reactor pool 30. A siphon breaking hole 34 is provided on the pipe wall of the main system inlet pipe 112. In different embodiments, one or more siphon breaking holes may be provided. The area of ​​a single opening is not greater than 35% of the diameter of the main system inlet pipe 112. The siphon breaking hole 34 is immersed below the cooling water level. The immersion depth is usually 1m-2m. Its height is higher than the top of the reactor core 10 and not lower than the height of the main system outlet pipe injector 39. The main system outlet pipe 111 is led out from the lower chamber 11 of the reactor, and includes an ascending section extending toward the cooling water surface and a descending section extending toward the bottom of the reactor pool 30. A hump pipe section 32 protruding upward is formed between the ascending section and the descending section. The height of the hump pipe section 32 is not less than 0.5 times the diameter of the main system outlet pipe 111. In a preferred embodiment, the hump pipe section 32 is immersed below the cooling water level. A branch pipeline is connected to the top of the hump pipe section 32, and a siphon breaking valve 31 is arranged on the branch pipeline. A siphon breaking valve outlet section 33 is arranged at the end of the branch pipeline. The siphon breaking valve outlet section 33 is also immersed below the cooling water level, usually with an immersion depth of 1m-2m, to prevent the siphon breaking valve 31 from accidentally opening under normal working conditions, resulting in air being sucked into the main system outlet pipe 111.

[0045] In a preferred embodiment, a plant spray water tank 71 is provided in the reactor building 70. The plant spray water tank 71 stores cooling water and is pressurized by 0.5MPa-5MPa nitrogen. A normally closed plant spray isolation valve 72 is provided between the plant spray water tank 71 and the plant spray head 73. The reactor building 70 is also provided with an active filtering exhaust 74.

[0046] In some embodiments, in combination Figure 2 For a pool-type reactor equipped with a high-temperature and high-pressure irradiation loop, the outlet of the irradiation loop pressure vessel 20 is connected to the inlet of the irradiation loop main heat exchanger 22 through the irradiation loop hot pipe section 24; the outlet of the irradiation loop main heat exchanger 22 is connected to the inlet of the irradiation loop circulation pump 23 through the irradiation loop transition section 25; the outlet of the irradiation loop circulation pump 23 is connected to the inlet of the irradiation loop pressure vessel 20 through the irradiation loop cold pipe section 26; the irradiation loop pressurizer is connected to the irradiation loop hot pipe section 24. In some embodiments, the high-temperature and high-pressure irradiation loop is immersed in the reactor water pool 30 and can be directly cooled and cooled by cooling water; in other embodiments, such as Figure 2As shown, the high temperature and high pressure irradiation circuit is arranged in the pressure compartment 60, and the pressure compartment 60 is arranged outside the reactor pool 30. The pressure compartment 60 is connected to the bubbler 65 through the pressure suppression tube check valve 64. The bubbler 65 is immersed below the liquid surface of the reactor pool 30, usually with an immersion depth of 2m-4m. The pressure suppression tube check valve 64 can prevent the water conduit in the reactor pool 30 from entering the pressure compartment 60. The wall of the pressure compartment 60 is provided with a metal plate, and the thickness of the metal plate can usually be set to 4mm-10mm to play the role of pressure bearing and heat conduction. The wall of the pressure compartment 60 is further provided with a bursting disc 66. When the pressure in the pressure compartment 60 exceeds the limit value, the bursting disc is detonated to achieve pressure relief of the pressure compartment 60. A compartment spray water tank 61 is provided in the pressure compartment 60 or in the reactor building 70 to store cooling water with nitrogen pressure, and a normally closed compartment spray isolation valve 62 is provided between the compartment spray water tank 61 and the compartment spray head 63. In the event of an accident, the compartment spray head 63 can be used to spray and cool the pressure compartment 60.

[0047] The irradiation circuit emergency waste heat discharge heat exchanger 27 is connected in parallel with the irradiation circuit main heat exchanger 22, and the outlet of the irradiation circuit pressure storage and injection tank 28 is respectively connected to the irradiation circuit hot pipe section 24 and the irradiation circuit cold pipe section 26. The irradiation circuit pressure storage and injection tank stores cooling water and stores pressure with 3MPa-5MPa nitrogen. The outlet of the irradiation circuit injection pump 29 is also respectively connected to the irradiation circuit hot pipe section 24 and the irradiation circuit cold pipe section 26. The irradiation circuit injection pump can be a combination of a high-pressure injection pump and a low-pressure injection pump, or it can only include a low-pressure injection pump. A normally closed irradiation circuit hot pipe section injection isolation valve 241 is provided between the irradiation circuit pressure storage and injection tank 28 and the irradiation circuit hot pipe section 24; a normally closed irradiation circuit cold pipe section injection isolation valve 261 is provided between the irradiation circuit cold pipe section 26 and the irradiation circuit injection pump 29. The irradiation loop hot pipe section injection isolation valve 241 and the irradiation loop cold pipe section injection isolation valve 261 can be a check valve or an isolation valve.

[0048] Under normal operating conditions, the main circulation pump 13 provides the forced circulation flow of the main system. The cooling water is input into the main heat exchanger 19 by the main circulation pump 13 for heat exchange and then enters the main system inlet pipe 112. Part of the cooling water leaks through the siphon destruction valve 34, and the rest flows to the main system inlet pipe ejector 35. Since the ejector isolation valve 36 downstream of the main system inlet pipe ejector 35 is in the pipe wall state, the cooling water entering the suction chamber 352 from the nozzle 351 flows back into the reactor water pool 30. The cooling water flows downward from the reactor core 10 into the reactor lower chamber 11 and takes away the heat generated by the reactor core 10, then enters the main system outlet pipe 111 through the reactor lower chamber outlet isolation valve 38, and enters the delay water tank 12 through the main system outlet pipe ejector 39 and the hump pipe section 32. The cooling water flowing through the main system outlet pipe ejector 39 will draw some additional cooling water from the reactor water pool 30 into the suction chamber 352 under the effect of ejection. The drainage ratio of the main system outlet pipe ejector 39, that is, the ratio of the diffuser outlet flow rate to the nozzle inlet flow rate, is 1.05-1.2. In the delay water tank 12, after the radioactive substances in the cooling water are decayed to a certain extent, they are pumped back into the main circulation pump 13 to continue circulation.

[0049] Under accident conditions, the main circulation pump 13 is a non-safety-level device and cannot guarantee normal operation. The safety control process includes the following steps:

[0050] First, the control rod assembly 50 is inserted into the reactor core 10 and / or the heavy water discharge isolation valve 52 is opened to inject the heavy water in the heavy water tank 51 into the reactor core 10 in a passive form, thereby achieving reactor shutdown by absorbing or moderating neutrons in the reactor core 10.

[0051] Next, open the waste outlet pipeline isolation valve 41 and the waste inlet pipeline isolation valve 42, so that a closed circulation loop is formed between the external heat exchanger 40 and the pool heat exchanger 45 by natural circulation, and the heat of the reactor pool is brought out to the external heat sink 80, ensuring that the cooling water in the reactor pool 30 does not boil after the accident. In a preferred embodiment, the heat carrying capacity of the external heat exchanger 40 and the pool heat exchanger 45 is 1%-3% of the rated power of the core. The heat capacity of the external heat sink 80 at least meets the core waste heat removal requirements for thirty days. With the help of the external heat sink cooling device 81, the cooling process can be carried out stably for a long time. The medium flowing in the external heat exchanger 40 and the pool heat exchanger 45 can be in the form of liquid or gas, for example, cooling water or evaporative medium in a heat pipe.

[0052] Since the main circulation pump 13 is a non-safety-level device and cannot be guaranteed to operate after the accident, the auxiliary circulation pump 14 is used to provide forced circulation for the main system after the accident. Since the auxiliary circulation pump 14 operates in the stage after the reactor is shut down, and the core decay heat is much smaller than the core power during normal operation, the flow rate of the auxiliary circulation pump 14 can be much smaller than that of the main circulation pump 13. In order to deal with a single failure, at least two auxiliary circulation pumps 14 are set in parallel, and the rated flow rate of a single auxiliary circulation pump 14 does not exceed 20% of the total flow rate of normal operation.

[0053] When the core decay heat is reduced to the first threshold value (1% to 2% of the core rated power), the ejector isolation valve 36 is opened and the reactor lower chamber outlet isolation valve 38 is closed (to prevent misoperation, the opening action of the ejector isolation valve 36 and the closing action of the reactor lower chamber outlet isolation valve 38 are interlocked). At this time, the flow from the auxiliary circulation pump 14 can enter the reactor lower chamber 11 through the main system inlet pipe ejector 35 and the ejector isolation valve 36, and then flow out of the reactor core 10 from bottom to top and enter the reactor water pool 30, realizing a rapid reversal of the core flow direction. The water entering the reactor water pool 30 can enter the main system outlet pipe 111 from the suction chamber of the main system outlet pipe ejector 39, and return to the inlet of the auxiliary circulation pump 14 to realize circulation. Since the entire process is driven by forced flow provided by the auxiliary circulation pump, compared with relying on natural circulation drive, flow stagnation when the core flow direction changes is avoided.

[0054] When the flow direction of the reactor core changes from bottom to top, the auxiliary circulation pump 14 can be closed to change from forced circulation in the main system loop to natural circulation in the reactor water pool, that is, the water in the reactor water pool 30 enters the lower chamber 11 of the reactor from the suction chamber of the main system inlet pipe ejector 35 through the ejector isolation valve 36, and then flows out of the reactor core 10 from bottom to top, enters the reactor water pool 30, and then enters the suction chamber of the main system inlet pipe ejector 35 again. When the core decay heat continues to decrease (when the core rated power is less than 1%), in order to further reduce the natural circulation resistance, the natural circulation valve 37 can be opened again. In order to deal with a single fault, at least two natural circulation valves 37 are set in parallel. The flow diameter of the natural circulation valve 37 is not less than the throat diameter of the main system inlet pipe ejector 35.

[0055] For a LOCA accident, if the breach is located at the portion where the main system outlet pipe 111 and the main system inlet pipe 112 are located inside the reactor water pool 30, the reactor water pool 30 will not lose water capacity.

[0056] If the breach is located outside the reactor pool 30 of the main system outlet pipe 111, the siphon breaking valve 31 can be opened. To deal with a single fault, at least two siphon breaking valves 31 are set in parallel. When the water level of the reactor pool 30 drops below the outlet pipe end 33 of the siphon breaking valve, air will be introduced into the hump pipe section 32 of the main system outlet pipe 111 through the siphon breaking valve 31 to block the flow channel, thereby preventing the water of the reactor pool 30 from further losing from the breach. Since the hump top of the hump pipe section 32 has a higher elevation and a smaller volume, it is conducive to the accumulation of air, so that the siphon breaking effect is better. In addition, as an optional design, the siphon breaking valve 31 is not set (or in extreme cases, if all siphon breaking valves 31 cannot be opened due to a fault), once the water level of the reactor pool 30 drops below the suction chamber of the main system outlet pipe ejector 39, air can also be sucked into the main system outlet pipe 111 from the main system outlet pipe ejector 39, which can also play a siphon breaking role. Since the main system outlet pipe ejector 39 is a non-active component, it has extremely high reliability.

[0057] If the breach is located outside the reactor pool 30 of the main system outlet pipe 112, when the water level of the reactor pool 30 drops below the siphon breaking hole 34, air will be introduced into the main system outlet pipe 112 through the siphon breaking hole 34 to block the flow path, thereby preventing further loss of water from the reactor pool 30 from the breach. Since the siphon breaking hole 34 is a passive component, it has extremely high reliability.

[0058] When the pressure of the reactor building 70 is high after an accident, the building spray isolation valve 72 can be opened, so that the cooling water in the building spray water tank 71 is driven by the pressurized gas to spray cooling water into the reactor building 70 through the building spray head 73, and the pressure of the reactor building 70 is quickly reduced in a short time, and the pressure is lower than the outside atmospheric pressure. In addition, the building active filtering exhaust 74 can be opened at the same time to continuously discharge the filtered gas from the reactor building 70, so as to prevent the pressure of the reactor building 70 from exceeding the limit value in the long stage after the building spray water tank 71 is exhausted, and the pressure is always lower than the outside atmospheric pressure.

[0059] For the pool reactor design provided with a high temperature and high pressure irradiation loop, when the high temperature and high pressure irradiation loop is designed to be immersed in the reactor pool 30, the high temperature and high pressure irradiation loop will be immersed in the cooling water of the reactor pool 30 and condensed after an accident that causes the release of high temperature and high pressure fluid occurs. When the high temperature and high pressure irradiation loop is arranged outside the reactor pool 30, the high temperature and high pressure irradiation loop is placed in the pressure compartment 60, so the high temperature and high pressure fluid released from the high temperature and high pressure irradiation loop will be contained in the pressure compartment 60. For the high temperature and high pressure fluid released into the pressure compartment 60, on the one hand, it enters the reactor pool 30 through the compartment pressure suppression pipe check valve 64 and the bubbler 65 and is condensed; on the other hand, the compartment spray isolation valve 62 can be opened, so that the cooling water in the compartment spray water tank 61 is driven by the pressure storage gas, and the cooling water is sprayed into the pressure compartment 60 through the compartment spray head 63, so that the pressure of the pressure compartment 60 is quickly reduced in a short time. In addition, a metal plate (thickness 4mm-10mm) is attached to the inner surface of the wall of the pressure compartment 60, which can not only absorb the heat of the high-temperature and high-pressure fluid in the compartment, but also ensure that the pressure compartment 60 has a high pressure bearing capacity. Finally, in extreme cases, even if the pressure of the pressure compartment 60 exceeds a certain limit, the bursting disk 66 can be opened to release the high-temperature and high-pressure fluid in the compartment into the reactor building 70 to prevent the pressure compartment 60 from being over-pressurized. After the high-temperature and high-pressure fluid is released into the reactor building 70, the reactor building 70 can ensure that the reactor building 70 will not be over-pressurized through diffusion and dilution (the volume of the reactor building 70 is much larger than that of the pressure compartment 60), building spraying, and active filtering and exhaust of the building, and the pressure is lower than the external atmospheric pressure.

[0060] For a pool-type reactor design equipped with a high-temperature and high-pressure irradiation loop, when a non-LOCA accident occurs, heat can be removed through the irradiation loop emergency residual heat removal heat exchanger 27, and the irradiation loop emergency residual heat removal heat exchanger 27 can be active or passive; when a LOCA accident occurs, due to the reduction in the system pressure of the high-temperature and high-pressure irradiation loop, the irradiation loop hot pipe section injection isolation valve 241 and the irradiation loop cold pipe section injection isolation valve 261 can be opened, and the irradiation loop pressure storage injection tank 28 is used up by the pressurized gas to replenish coolant into the loop. When the irradiation loop pressure storage injection tank 28 is exhausted, the irradiation loop injection pump 29 can continue to replenish coolant into the loop, and the source of the coolant can be the reactor water pool 30. The irradiation circuit pressure storage injection tank 28 and the irradiation circuit injection pump 29 replenish coolant to the irradiation circuit hot pipe section 24 and the irradiation circuit cold pipe section 26 by simultaneously passing through the irradiation circuit hot pipe section injection isolation valve 241 and the irradiation circuit cold pipe section injection isolation valve 261, ensuring that no matter whether the rupture occurs in the irradiation circuit hot pipe section 24 or the irradiation circuit cold pipe section 26, the coolant can enter the circuit instead of flowing around the rupture.

[0061] The pool-type reactor safety management method provided in the above-mentioned embodiment combines active safety technology with passive safety technology. In view of the structural characteristics of the pool-type reactor, it can effectively realize rapid shutdown and residual heat discharge under accident conditions, prevent core overheating caused by stagnation of reactor core cooling water after the main circulation pump is shut down, reduce the risk of leakage of radioactive materials, and effectively improve the safety and reliability of the pool-type reactor.

[0062] The purpose of the above embodiments is to further explain the present invention in detail in conjunction with the accompanying drawings so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, the optimization or equivalent replacement of the part structure or method steps involved, and the combination of implementation methods in different embodiments without conflict of structure and principle, all fall within the protection scope of the present invention.

Claims

1. A pool-type reactor safety management system, characterized in that: include: Shutdown device, passive residual heat removal device, main circulation device, auxiliary circulation device and passive circulation device, among which, The shutdown device is used to intervene in the reactor core to achieve shutdown under accident conditions; The passive residual heat removal device comprises a water pool heat exchanger, an external heat exchanger and an external heat sink, wherein the water pool heat exchanger is arranged in the reactor water pool, the external heat exchanger is arranged in the external heat sink, the water pool heat exchanger is connected with the external heat exchanger to form a circulation loop, and forms a natural circulation when the temperature of the water pool heat exchanger is higher than that of the external heat exchanger; The main circulation device comprises a main circulation pump and a circulation pipeline, wherein the main circulation pump drives the cooling water to circulate under normal working conditions; the two ends of the circulation pipeline are respectively connected to the lower chamber of the reactor, and a siphon breaking hole is arranged at a position upstream of the lower chamber of the reactor and higher than the reactor core; the circulation pipeline is provided with an isolation device upstream of the lower chamber of the reactor, when the isolation device is turned off, the cooling water in the circulation pipeline flows into the reactor water pool through the isolation device, and when the isolation device is opened, at least part of the cooling water in the circulation pipeline flows into the lower chamber of the reactor through the isolation device; The auxiliary circulation device comprises an auxiliary circulation pump, and the auxiliary circulation pump is connected in parallel to the main circulation pump; The passive circulation device includes a natural circulation valve arranged in the lower chamber of the reactor.

2. The pool-type reactor safety management system according to claim 1, characterized in that: The shutdown device includes a control rod assembly and / or a heavy water tank. The control rod assembly includes a neutron absorber control rod, and the control rod assembly can insert the neutron absorber control rod into the core; the heavy water tank stores heavy water, and the heavy water tank can inject the heavy water into the core in a passive form.

3. The pool-type reactor safety management system according to claim 1 or 2, characterized in that: The external heat sink is also provided with an external heat sink cooling device for reducing the temperature of the external heat sink.

4. The pool reactor safety management system according to claim 1 or 2, characterized in that: The isolation device includes a main system inlet pipe ejector and an ejector isolation valve; The main system inlet pipe ejector includes a nozzle, a suction chamber, a throat and a diffuser; The nozzle is connected to the upstream circulation pipeline; the suction chamber is in a bell-mouth shape with an enlarged diameter at one end toward the nozzle and is connected to the reactor water pool, and the other end is connected to the throat; one end of the diffuser is connected to the throat, and the other end gradually enlarges in diameter and is connected to the ejector isolation valve; The main system inlet pipe ejector is connected to the lower chamber of the reactor through an ejector isolation valve. When the ejector isolation valve is closed, the cooling water in the circulation pipeline flows back into the reactor water pool through the main system inlet pipe ejector. When the ejector isolation valve is opened, at least part of the cooling water in the circulation pipeline and part of the cooling water in the reactor water pool flow into the lower chamber of the reactor through the main system inlet pipe ejector.

5. The pool-type reactor safety management system according to claim 4, characterized in that: The drainage ratio of the main system inlet pipe ejector is 1.05-1.

2.

6. The pool-type reactor safety management system according to claim 1 or 2, characterized in that: The circulation pipeline is also provided with a main system outlet pipe injector downstream of the reactor lower chamber, and the main system outlet pipe injector includes a nozzle, a suction chamber, a throat and a diffusion pipe; The nozzle is connected to the upstream circulation pipeline; the suction chamber is in a trumpet shape with an enlarged diameter at one end toward the nozzle and is connected to the reactor water pool, and the other end is connected to the throat; one end of the diffuser is connected to the throat, and the other end gradually enlarges in diameter and is connected to the circulation pipeline.

7. The pool reactor safety management system according to claim 1 or 2, characterized in that: It also includes a spray system, which includes a passive water storage tank. The passive water storage tank can spray cooling water to the plant building where the reactor is located under accident conditions.

8. The pool-type reactor safety management system according to claim 7, characterized in that: It also includes a filtering and exhausting system, which is used to filter radioactive pollutants and exhaust the gas in the plant where the reactor is located.

9. The pool-type reactor safety management system according to claim 1 or 2, characterized in that: The pool reactor is equipped with high-temperature and high-pressure irradiation pipelines; The pool-type reactor safety management system includes a pressure compartment, the high-temperature and high-pressure irradiation pipeline is enclosed in the pressure compartment, and the wall of the pressure compartment is provided with a heat conducting plate to conduct heat out of the pressure compartment; the pressure compartment also includes a pressure suppression tube, one end of the pressure suppression tube is connected to the pressure compartment and the other end is immersed in the cooling water of the reactor pool, and a check valve and a bubbler are provided.

10. The pool-type reactor safety management system according to claim 9, characterized in that: The pressure-bearing compartment is also provided with a bursting disc, and when the bursting disc explodes, the pressure-bearing compartment is depressurized.

11. A pool reactor safety management method, characterized in that: A pool-type reactor safety management system according to any one of claims 1 to 10 is used, and comprises the following steps: In accident conditions, Step a): starting the shutdown device to shut down the reactor; Step b): using the auxiliary circulation pump to force cooling water to circulate until the core decay heat is reduced to below a first threshold value of the rated power; Step c): opening the isolation device, shutting off the downstream pipeline of the lower chamber of the reactor, and allowing the auxiliary circulation pump to drive cooling water to flow into the lower chamber of the reactor through the isolation device and out of the upper part of the reactor, so as to achieve the reversal of the flow direction of the core cooling water; Step d): after the flow direction of the core cooling water is reversed, the auxiliary circulation pump is turned off to perform natural circulation; Step e): when the core decay heat decreases below a second threshold value of the rated power, opening the natural circulation valve.

12. The pool reactor safety management method according to claim 11, characterized in that: The first threshold is 2% of the rated power of the core; the second threshold is 1% of the rated power of the core.

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