Novel high-temperature gas cooled reactor accident mitigation measure nitrogen injection and oxygen control system

Abstract

The invention belongs to the technical field of nuclear power station out-of-design-basis accident condition accident mitigation measures, and particularly relates to a novel high-temperature gas cooled reactor accident mitigation measure nitrogen injection and oxygen control system. The large-flow nitrogen injection system is used for middle inflation and lower exhaust, under the accident working condition exceeding the design basis, a primary loop pipe breakage accident occurrence area is located in a reactor pressure vessel cabin and a loading and unloading main circulation cabin, and after the large-flow nitrogen supply system is put into operation, an initial nitrogen concentration environment of the cabins is rapidly established; meanwhile, the oxygen concentration of the internal environment of a reactor building is reduced to a safe concentration range, and a large amount of oxygen is prevented from entering a reactor pressure vessel core; after an initial nitrogen concentration environment of a reactor building is created in the large-flow nitrogen injection system, the large-flow nitrogen injection system is stopped, and then the small-flow nitrogen injection system is started. Influences caused by accidents are effectively relieved, and large-scale release of radioactive fission products caused by secondary disasters is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of accident mitigation measures for ultra-design basis accident conditions in nuclear power plants, and in particular relates to a novel nitrogen injection and oxygen control system for accident mitigation measures for high-temperature gas-cooled reactors. Background Art

[0002] As a reactor type with fourth-generation nuclear power technology, the pebble-bed modular high-temperature gas-cooled reactor (hereinafter referred to as "high-temperature gas-cooled reactor") has inherent safety characteristics. It uses graphite-coated fuel balls, and the core also uses graphite as a moderator. Therefore, the pressure vessel of the high-temperature gas-cooled reactor must prevent the entry of oxygen and water vapor to avoid redox reactions with graphite to generate flammable and explosive gases. Especially under the beyond-design basis accident conditions where non-isolated breaches occur at the upper and lower parts of the high-temperature gas-cooled reactor primary loop system (feed pipe and discharge pipe), the formed flow channel will allow a large amount of oxygen to enter the reactor pressure vessel, causing more serious consequences. In order to avoid the occurrence of the above accident sequence, an effective method is to quickly control the oxygen concentration in the ambient air in the area where the pipe breaks, and reduce the oxygen concentration to a safe range by quickly injecting a large amount of nitrogen.

[0003] In order to achieve the above-mentioned goals, a set of accident mitigation measures unique to high-temperature gas-cooled reactors was designed - a nitrogen production and oxygen control system. Through the continuous operation of the nitrogen production and oxygen control system after the above-mentioned accident conditions, the nitrogen concentration in the area where the first-loop system pipe rupture accident occurred and the reactor building is maintained within a safe concentration range, thereby preventing a large amount of oxygen from entering the reactor pressure vessel and undergoing redox reactions with graphite. Summary of the invention

[0004] The purpose of the present invention is to provide a novel nitrogen injection and oxygen control system for high temperature gas-cooled reactor accident mitigation measures, which is put into use when a high temperature gas-cooled reactor occurs an accident condition beyond the design basis, effectively mitigating the impact of the accident, avoiding secondary disasters, and causing large-scale release of radioactive fission products.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A novel high-temperature gas-cooled reactor accident mitigation measure nitrogen injection oxygen control system includes a large-flow nitrogen injection system and a small-flow nitrogen injection system. The large-flow nitrogen injection system includes a large-flow nitrogen supply system and an exhaust purification system, and the small-flow nitrogen injection system includes a nitrogen production system and a nitrogen return system. The large-flow nitrogen injection system is intermediate inflation and lower exhaust. Under the ultra-design basis accident condition, the primary circuit pipe break accident occurs in the reactor pressure vessel compartment and the main circulation compartment for loading and unloading. After the large-flow nitrogen supply system is put into operation, the initial nitrogen concentration environment of the above compartments is quickly established, and the oxygen concentration in the internal environment of the reactor building is reduced to a safe concentration range, thereby preventing a large amount of oxygen from entering the reactor pressure vessel core; The exhaust volume of the exhaust purification system is greater than the nitrogen supply volume of the large-flow nitrogen supply system, so that the reactor building is maintained in a relatively negative pressure state to prevent the release of radioactive substances to the outdoor environment; after the large-flow nitrogen injection system creates the initial nitrogen concentration environment of the reactor building, the large-flow nitrogen injection system is shut down, and then the small-flow nitrogen injection system is started; the small-flow nitrogen injection system is middle-filled and bottom-exhausted, and the nitrogen concentration in the internal environment of the reactor building is continuously increased and maintained through the continuous operation of the small-flow nitrogen injection system, and the nitrogen production of the nitrogen production system is greater than the return volume of the nitrogen return system, so that the reactor building is maintained in a relatively positive pressure state to prevent the entry of oxygen from the indoor atmospheric environment.

[0007] The large-flow nitrogen supply system includes a liquid nitrogen tank group, an electric ball valve, a buffer tank, a pressure reducing valve, a check valve, a manual stop valve, a flow meter, an electric regulating valve, and a nitrogen pipeline. The outlet of the liquid nitrogen tank group is connected to the inlet of the electric ball valve through a nitrogen pipeline, the outlet of the electric ball valve is connected to the inlet of the buffer tank after confluence through a nitrogen pipeline, the outlet of the buffer tank is connected to the inlet of the pressure reducing valve through a nitrogen pipeline, the outlet of the pressure reducing valve is connected to the inlet of the check valve through a nitrogen pipeline, the outlet of the check valve is connected to the inlet of the manual stop valve through a nitrogen pipeline, the outlet of the manual stop valve is connected to the inlet of the electric regulating valve through a nitrogen pipeline, a flow meter is provided on the intermediate pipeline between the manual stop valve and the electric regulating valve, the outlet of the electric regulating valve is connected to the nitrogen pipeline into the reactor building, and is connected to each reactor pressure vessel compartment and the main circulation compartment for loading and unloading through each branch pipe on the air supply ring pipeline.

[0008] The exhaust purification system includes an iodine adsorber, a centrifugal fan, an electric air duct sealed valve, an air duct type regulating valve, an air duct type flow meter, and an exhaust duct. The two exhaust ducts are connected to the inlet of the electric air duct sealed valve after leaving the reactor building. The outlet of the electric air duct sealed valve is connected to the inlet of the iodine adsorber after converging through the exhaust duct. The outlet of the iodine adsorber is respectively connected to the inlet of the air duct type regulating valve of each branch after being diverted through the exhaust duct. The outlet of the air duct type regulating valve is connected to the inlet of the centrifugal fan through the exhaust duct. The outlet of the centrifugal fan is connected to the inlet of the electric air duct sealed valve on its branch through the exhaust duct. The outlet of the electric air duct sealed valve is connected to the chimney after converging through the exhaust duct. A duct type flow meter is provided on the exhaust duct upstream of the chimney.

[0009] The nitrogen production system includes a pressure reducing valve, a check valve, a manual stop valve, a flow meter, an electric regulating valve, a complete set of nitrogen production equipment, and a nitrogen pipeline. The outlet of the complete set of nitrogen production equipment is connected to the inlet of the pressure reducing valve through a nitrogen pipeline, the outlet of the pressure reducing valve is connected to the inlet of the check valve through a nitrogen pipeline, the outlet of the check valve is connected to the inlet of the manual stop valve through a nitrogen pipeline, a flow meter is provided on the pipeline between the check valve and the manual stop valve, the outlet of the manual stop valve is connected to the inlet of the electric regulating valve through a nitrogen pipeline, and the outlet of the electric regulating valve is connected to the nitrogen pipeline to enter the reactor building.

[0010] The nitrogen return system includes a manual stop valve, a flow meter, an electric control valve, a three-way connector, and a nitrogen pipeline. The nitrogen pipeline exiting the reactor building is connected to the inlet of the electric control valve. The outlet of the electric control valve is connected to the inlet of the manual stop valve through the nitrogen pipeline. A flow meter is arranged on the intermediate pipeline between the electric control valve and the manual stop valve. The outlet of the manual stop valve is connected to the inlet at one end of the three-way connector through the nitrogen pipeline. The inlet at the other end of the three-way connector is connected to the outlet of the manual stop valve. The inlet of the manual stop valve is connected to a section of pipeline for indoor air intake. A flow meter is arranged on this section of pipeline.

[0011] The complete set of nitrogen making equipment includes an air compressor unit, a wet air buffer tank, a drying and purifying unit, an activated carbon filter, a dry air buffer tank, a nitrogen making unit, a nitrogen process tank, a nitrogen storage tank, and a nitrogen making equipment connecting pipe. The outlet of the air compressor unit is connected to the inlet of the wet air buffer tank through the nitrogen making equipment connecting pipe, the outlet of the wet air buffer tank is connected to the inlet of the drying and purifying unit through the nitrogen making equipment connecting pipe, the outlet of the drying and purifying unit is connected to the inlet of the activated carbon filter through the nitrogen making equipment connecting pipe, the outlet of the activated carbon filter is connected to the inlet of the dry air buffer tank through the nitrogen making equipment connecting pipe, the outlet of the dry air buffer tank is connected to the inlet of the nitrogen making unit through the nitrogen making equipment connecting pipe, the outlet of the nitrogen making unit is connected to the inlet of the nitrogen process tank through the nitrogen making equipment connecting pipe, the outlet of the nitrogen process tank is connected to the inlet of the nitrogen storage tank through the nitrogen making equipment connecting pipe, and the outlet of the nitrogen storage tank is connected to the main pipe of the nitrogen making system.

[0012] The beneficial effects achieved by the present invention are:

[0013] The nitrogen production and oxygen control system is a unique accident mitigation measure for high-temperature gas-cooled reactors beyond the design basis accident, and is a newly added system. By rapidly injecting nitrogen into the reactor building and the accident area, the oxygen concentration is reduced to a safe range, and the nitrogen concentration in the reactor building is maintained in stages to avoid the risk of explosion in the event of an beyond the design basis accident. Compared with the accident mitigation measure used in pressurized water reactors - the passive injection system, the nitrogen production and oxygen control system has a lower cost, a simple system composition, and is easy to operate. The investment in the system will basically have no impact on the reactor core. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a process flow chart of a new type of high temperature gas-cooled reactor accident mitigation measure, nitrogen injection and oxygen control system;

[0015] Figure 2 It is the process layout diagram of the complete set of nitrogen production equipment;

[0016] In the figure: a large-flow nitrogen supply system 1; an exhaust purification system 2; a liquid nitrogen tank group 3; an electric ball valve 4; a buffer tank 5; a pressure reducing valve 6; a check valve 7; a manual stop valve 8; a flow meter 9; an electric regulating valve 10; a nitrogen pipeline 11; an iodine adsorber 12; a centrifugal fan 13; an electric air duct sealing valve 14; an air duct regulating valve 15; an air duct flow meter 16; an exhaust duct 17; a nitrogen making system 18; a nitrogen return system 19; a complete set of nitrogen making equipment 20; a three-way connector 21; an air compressor unit 22; a wet air buffer tank 23; a drying and purification unit 24; an activated carbon filter 25; a dry air buffer tank 26; a nitrogen making unit 27; a nitrogen process tank 28; a nitrogen storage tank 29; and a nitrogen making equipment connecting pipe 30. DETAILED DESCRIPTION

[0017] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] The nitrogen production and oxygen control system is divided into two subsystems: a large-flow nitrogen injection system and a small-flow nitrogen injection system. The large-flow nitrogen injection system includes a large-flow nitrogen supply system 1 and an exhaust purification system 2. The large-flow nitrogen supply system includes a liquid nitrogen tank group 3 and an electric ball valve 4 at its outlet, a buffer tank 5, a pressure reducing valve 6, a check valve 7, 6 manual stop valves 8, 11 flow meters 9, 17 electric regulating valves 10, and a nitrogen pipeline 11. The exhaust purification system includes an iodine adsorber 12, 2 centrifugal fans 13, 4 electric air duct sealing valves 14, 2 air duct regulating valves 15, 1 air duct flow meter 16, and an exhaust duct 17. The small-flow nitrogen injection system includes 3 nitrogen production systems 18 and 3 nitrogen return air systems 19. Each nitrogen production system includes a set of complete nitrogen production equipment 20, a set of pressure reducing valves 6, an electric regulating valve 10, a check valve 7, a set of flow meters 9, and a nitrogen pipeline 11. Each set of complete nitrogen production equipment includes an air compressor unit 22, a wet air buffer tank 23, a dry purification unit 24, an activated carbon filter 25, a dry air buffer tank 26, a nitrogen production unit 27, a nitrogen process tank 28, a nitrogen storage tank 29, and a nitrogen production equipment connecting pipe 30. Each nitrogen return system includes an electric regulating valve 10, two manual stop valves 8, two flow meters 9, a three-way connector 21, and a nitrogen pipeline 11.

[0019] Operation function of large-flow nitrogen injection system: The large-flow nitrogen injection system adopts the airflow design scheme of middle inflation and lower exhaust. Under the beyond-design basis accident conditions, the area where the primary circuit pipe break accident occurs is located in the reactor pressure vessel compartment (the compartment where the feed pipe is located) and the main circulation compartment for loading and unloading (the compartment where the discharge pipe is located). After the large-flow nitrogen injection system is put into operation, the initial nitrogen concentration environment of the above compartments can be quickly established (the nitrogen concentration is not less than 95%), and at the same time, the oxygen concentration in the internal environment of the reactor building is reduced to a safe concentration range (the oxygen concentration is reduced to below 12.5%) to prevent a large amount of oxygen from entering the reactor pressure vessel core. By setting the difference between the exhaust volume of the exhaust purification system and the nitrogen supply volume of the large-flow nitrogen supply system, the reactor building is maintained in a relatively negative pressure state to prevent the release of radioactive substances to the outdoor environment. After the large-flow nitrogen injection system creates the initial nitrogen concentration environment of the reactor building, the large-flow nitrogen injection system is shut down, and then the small-flow nitrogen injection system is turned on.

[0020] Operation function of small flow nitrogen injection system: The small flow nitrogen injection system adopts the airflow design scheme of middle filling and lower exhaust. Through the continuous operation of the small flow nitrogen injection system, the nitrogen concentration in the reactor building is continuously increased and maintained. By setting the difference between the nitrogen production volume of the nitrogen production system and the return volume of the nitrogen return system, the reactor building is maintained in a relatively positive pressure state to prevent the entry of oxygen in the indoor atmosphere. The system equipment, valves, pipelines and their supports and hangers can withstand earthquakes that cause safe shutdown.

[0021] The nitrogen production and oxygen control system is divided into two subsystems: a large-flow nitrogen injection system and a small-flow nitrogen injection system. The large-flow nitrogen injection system adopts an airflow design scheme of middle inflation and lower exhaust. Under the beyond-design basis accident conditions, the area where the primary circuit pipe break accident occurs is located in the reactor pressure vessel compartment (the compartment where the feed pipe is located) and the main circulation compartment for loading and unloading (the compartment where the unloading pipe is located). After the large-flow nitrogen injection system is put into operation, the initial nitrogen concentration environment of the above compartments can be quickly established (the nitrogen concentration is not less than 95%), and at the same time, the oxygen concentration in the internal environment of the reactor building is reduced to a safe concentration range (the oxygen concentration is reduced to below 12.5%), preventing a large amount of oxygen from entering the reactor pressure vessel core. By setting the difference between the exhaust volume of the exhaust purification system and the nitrogen supply volume of the large-flow nitrogen supply system, the reactor building is maintained in a relatively negative pressure state to prevent the release of radioactive substances to the outdoor environment. After the large-flow nitrogen injection system creates the initial nitrogen concentration environment of the reactor building, the large-flow nitrogen injection system is shut down, and then the small-flow nitrogen injection system is turned on. The small-flow nitrogen injection system adopts the airflow design scheme of middle filling and lower exhaust. Through the continuous operation of the small-flow nitrogen injection system, the nitrogen concentration in the reactor building environment is continuously increased and maintained. By setting the difference between the nitrogen production volume of the nitrogen production system and the return volume of the nitrogen return system, the reactor building is maintained in a relatively positive pressure state to prevent the entry of oxygen from the indoor atmospheric environment.

[0022] Operation plan of large-flow nitrogen supply system: When the above-design basis accident conditions occur, the electric ball valve downstream of the liquid nitrogen tank (normally closed) is opened in sequence, and the liquid nitrogen is depressurized, expanded and gasified and enters the buffer tank. After being depressurized by a set of pressure reducing valves (reduced to 1MPa), the nitrogen enters the reactor building through the nitrogen main pipeline. The main road is also equipped with a manual stop valve (for flow regulation during the commissioning phase), a check valve (to prevent nitrogen backflow), a set of flow meters (for nitrogen supply monitoring), and an electric regulating valve (opened when the system is running, used for flow regulation during the operation phase, normally closed, and set outside the reactor building boundary to ensure the integrity of the reactor building pressure boundary). After the nitrogen enters the reactor building, it enters the nitrogen loop that is symmetrically arranged relative to the C-type building layout of the reactor building. The nitrogen loop is equipped with 13 branches, of which 3 branches supply nitrogen to the reactor building, with an angle of 120° between them, and a normally open manual stop valve (for flow adjustment during the commissioning stage) is set at the end; 10 branches are connected to 10 reactor pressure vessel cabins and the main circulation cabin for loading and unloading respectively. Each branch is equipped with an electric regulating valve (normally closed, open when power is off, and can also be used for remote regulation of nitrogen flow during system operation) and a set of flow meters on the outside of the cabin. It is divided into two branches downstream to lead nitrogen to the inside of the above two cabins respectively. Nitrogen enters the reactor building and the reactor pressure vessel cabin and the main circulation cabin for loading and unloading where the pipe break accident occurred through the above nitrogen loop, branches and branches. In view of the requirements of the single failure criterion, it is considered that only one reactor pressure vessel cabin and the main circulation cabin for loading and unloading have a pipe break accident in the primary circuit system. The electric regulating valve on the outside of the cabin where the pipe break accident occurred is opened remotely, and the electric regulating valves on the outside of other cabins where the pipe break accident did not occur remain closed.

[0023] Exhaust purification system operation plan: This system operates simultaneously with the large-flow nitrogen supply system to purify and discharge radioactive substances. By setting the difference between the supply and exhaust air volumes, the reactor building is maintained in a relatively negative pressure state to prevent the release of radioactive substances to the outdoor environment. Two exhaust branches are set at the bottom of the reactor building, located on both sides of the C-shaped port of the reactor building, and arranged symmetrically. The leaked primary helium and other gases in the internal environment of the reactor building are discharged from the reactor building through the two exhaust branches, enter the exhaust main road, and then enter the iodine adsorber for iodine removal and purification. After that, they are discharged to the chimney through the exhaust fan (1 in use and 1 in reserve), and then discharged to the outdoor atmosphere through the chimney. Both discharge branches are equipped with an electric air duct sealing valve (open when the system is running, normally closed, set outside the reactor building boundary to ensure the integrity of the reactor building pressure boundary). An electric air duct sealing valve is installed at the exhaust fan outlet (open when the system is running, normally closed to ensure that the system is isolated from the atmosphere of other systems when it is shut down), and an air duct regulating valve is installed at the inlet (for air volume balance during the debugging stage). A set of air duct flow meters is installed downstream of the exhaust fan (for exhaust volume monitoring).

[0024] Operation plan of nitrogen production system: The complete set of nitrogen production equipment of the nitrogen production system adopts centralized control. When the nitrogen concentration in the reactor building reaches 87.5%, the complete set of nitrogen production equipment is started with one button. After the fresh air is pressurized by the air compressor unit, it enters the wet air buffer tank, and then enters the dry purification unit for treatment, and then enters the activated carbon filter. After purification again, it enters the dry air buffer tank, and then enters the nitrogen production unit to produce nitrogen. Nitrogen process tanks and nitrogen storage tanks are set downstream of the nitrogen production unit. The produced nitrogen is reduced in pressure by the pressure reducing valve group and enters the reactor building through a small flow nitrogen supply pipeline. The nitrogen production system trunk line is also equipped with a manual shut-off valve (for flow regulation in the debugging stage), a check valve (to prevent nitrogen backflow), a set of flow meters (for nitrogen supply monitoring), and an electric regulating valve (open when the system is running, used for flow regulation in the operation stage, normally closed, set outside the reactor building boundary to ensure the integrity of the reactor building pressure boundary). The system is equipped with 3 sets of identical nitrogen production equipment, and the nitrogen supply pipelines are independently set up and arranged in three directions of the reactor building to maintain the uniformity of nitrogen concentration. Each set of nitrogen production equipment provides 500Nm 3 / h nitrogen, 3 sets of equipment provide a total of 1500Nm 3 / h nitrogen.

[0025] Nitrogen return air system operation plan: The nitrogen return air system relies on the negative pressure provided by the air compressor unit to extract gas from the reactor building into the air compressor unit, so that the gas inside the reactor building circulates, continuously discharges oxygen, and gradually increases the concentration of nitrogen inside the reactor building. The system is equipped with an electric regulating valve on the outside of the reactor building (open when the system is running, used for flow adjustment during the operation stage, normally closed, and set outside the boundary of the reactor building to ensure the integrity of the pressure boundary of the reactor building). A three-way connector for the return air and fresh air convergence is set at the air inlet of the air compressor unit, and a manual stop valve and a set of flow meters are set on the return air and fresh air branches for adjusting and monitoring the return air and fresh air flow rates to maintain a return air volume of 300Nm for each system. 3 / h, fresh air volume 200Nm 3 / h.

[0026] The large-flow nitrogen supply system 1 includes: a liquid nitrogen tank group 3, an electric ball valve 4, a buffer tank 5, a pressure reducing valve 6, a check valve 7, a manual stop valve 8, a flow meter 9, an electric regulating valve 10, and a nitrogen pipeline 11. The outlet of the liquid nitrogen tank group 3 is connected to the inlet of the electric ball valve 4 through the nitrogen pipeline 11, the outlet of the electric ball valve 4 is connected to the inlet of the buffer tank 5 after converging through the nitrogen pipeline 11, the outlet of the buffer tank 5 is connected to the inlet of the pressure reducing valve 6 through the nitrogen pipeline 11, the outlet of the pressure reducing valve 6 is connected to the inlet of the check valve 7 through the nitrogen pipeline 11, the outlet of the check valve 7 is connected to the inlet of the manual stop valve 8 through the nitrogen pipeline 11, the outlet of the manual stop valve 8 is connected to the inlet of the electric regulating valve 10 through the nitrogen pipeline 11, and a flow meter 9 is provided on the intermediate pipeline between the manual stop valve 8 and the electric regulating valve 10. The outlet of the electric regulating valve 10 is connected to the nitrogen pipeline 11 into the reactor building, and is connected to each reactor pressure vessel compartment and the main circulation compartment for loading and unloading through each branch pipe on the gas supply annular pipeline.

[0027] The exhaust purification system 2 comprises: an iodine adsorber 12, a centrifugal fan 13, an electric air duct sealed valve 14, an air duct type regulating valve 15, an air duct type flow meter 16, and an exhaust duct 17. The two exhaust ducts 17 are connected to the inlet of the electric air duct sealed valve 14 after leaving the reactor building, the outlet of the electric air duct sealed valve 14 is connected to the inlet of the iodine adsorber 12 after converging through the exhaust duct 17, the outlet of the iodine adsorber 12 is respectively connected to the inlet of each branch air duct type regulating valve 15 after being split through the exhaust duct 17, the outlet of the air duct type regulating valve 15 is connected to the inlet of the centrifugal fan 13 through the exhaust duct 17, the outlet of the centrifugal fan 13 is connected to the inlet of the electric air duct sealed valve 14 on its branch through the exhaust duct 17, the outlet of the electric air duct sealed valve 14 is connected to the chimney after converging through the exhaust duct 17, and the exhaust duct 17 upstream of the chimney is provided with an air duct type flow meter 16.

[0028] The nitrogen production system 18 includes: a pressure reducing valve 6, a check valve 7, a manual stop valve 8, a flow meter 9, an electric regulating valve 10, a complete set of nitrogen production equipment 20, and a nitrogen pipeline 11. The outlet of the complete set of nitrogen production equipment 20 is connected to the inlet of the pressure reducing valve 6 through the nitrogen pipeline 11, the outlet of the pressure reducing valve 6 is connected to the inlet of the check valve 7 through the nitrogen pipeline 11, the outlet of the check valve 7 is connected to the inlet of the manual stop valve 8 through the nitrogen pipeline 11, a flow meter 9 is provided on the pipeline between the check valve 7 and the manual stop valve 8, the outlet of the manual stop valve 8 is connected to the inlet of the electric regulating valve 10 through the nitrogen pipeline 11, and the outlet of the electric regulating valve 10 is connected to the nitrogen pipeline 11 to enter the reactor building.

[0029] The nitrogen return system 19 includes: a manual stop valve 8, a flow meter 9, an electric regulating valve 10, a three-way connector 21, and a nitrogen pipeline 11. The nitrogen pipeline 11 is connected to the inlet of the electric regulating valve 10 at the reactor building, and the outlet of the electric regulating valve 10 is connected to the inlet of the manual stop valve 8 through the nitrogen pipeline 11. The flow meter 9 is arranged on the intermediate pipeline between the electric regulating valve 10 and the manual stop valve 8. The outlet of the manual stop valve 8 is connected to the inlet of one end of the three-way connector 21 through the nitrogen pipeline 11, and the inlet of the other end of the three-way connector 21 is connected to the outlet of the manual stop valve 8. The inlet of the manual stop valve 8 is connected to a section of pipeline for indoor air intake, and the flow meter 9 is arranged on this section of pipeline.

[0030] The complete set of nitrogen production equipment includes: an air compressor unit 22, a wet air buffer tank 23, a drying and purification unit 24, an activated carbon filter 25, a dry air buffer tank 26, a nitrogen production unit 27, a nitrogen process tank 28, a nitrogen storage tank 29, and a nitrogen production equipment connecting pipe 30. The outlet of the air compressor unit 22 is connected to the inlet of the wet air buffer tank 23 through the nitrogen making equipment connecting pipe 30, the outlet of the wet air buffer tank 23 is connected to the inlet of the drying and purification unit 24 through the nitrogen making equipment connecting pipe 30, the outlet of the drying and purification unit 24 is connected to the inlet of the activated carbon filter 25 through the nitrogen making equipment connecting pipe 30, the outlet of the activated carbon filter 25 is connected to the inlet of the dry air buffer tank 26 through the nitrogen making equipment connecting pipe 30, the outlet of the dry air buffer tank 26 is connected to the inlet of the nitrogen making unit 27 through the nitrogen making equipment connecting pipe 30, the outlet of the nitrogen making unit 27 is connected to the inlet of the nitrogen process tank 28 through the nitrogen making equipment connecting pipe 30, the outlet of the nitrogen process tank 28 is connected to the inlet of the nitrogen storage tank 29 through the nitrogen making equipment connecting pipe 30, and the outlet of the nitrogen storage tank 29 is connected to the main pipe of the nitrogen making system.

Claims

1. A new type of high temperature gas-cooled reactor accident mitigation measure nitrogen injection oxygen control system, Features: It includes a large-flow nitrogen injection system and a small-flow nitrogen injection system. The large-flow nitrogen injection system includes a large-flow nitrogen supply system and an exhaust purification system, and the small-flow nitrogen injection system includes a nitrogen production system and a nitrogen return system. The large-flow nitrogen injection system is intermediate inflation and lower exhaust. Under the beyond-design basis accident conditions, the primary circuit pipe break accident area is located in the reactor pressure vessel compartment and the main circulation compartment for loading and unloading. After the large-flow nitrogen supply system is put into operation, the initial nitrogen concentration environment of the above compartments is quickly established, and at the same time, the oxygen concentration in the internal environment of the reactor building is reduced to a safe concentration range to prevent a large amount of oxygen from entering the reactor pressure vessel core; the exhaust volume of the exhaust purification system The difference setting method is greater than the nitrogen supply amount of the large-flow nitrogen supply system, so that the reactor building is maintained in a relatively negative pressure state to prevent the release of radioactive substances to the outdoor environment; after the large-flow nitrogen injection system creates the initial nitrogen concentration environment of the reactor building, the large-flow nitrogen injection system is shut down, and then the small-flow nitrogen injection system is started; the small-flow nitrogen injection system is middle-filled and lower-exhausted, and the nitrogen concentration in the internal environment of the reactor building is continuously increased and maintained through the continuous operation of the small-flow nitrogen injection system, and the nitrogen production of the nitrogen production system is greater than the return air volume of the nitrogen return system. The reactor building is maintained in a relatively positive pressure state to prevent the entry of oxygen from the indoor atmospheric environment.

2. According to the novel high temperature gas-cooled reactor accident mitigation measure nitrogen injection and oxygen control system of claim 1, Features: The large-flow nitrogen supply system includes a liquid nitrogen tank group, an electric ball valve, a buffer tank, a pressure reducing valve, a check valve, a manual stop valve, a flow meter, an electric regulating valve, and a nitrogen pipeline. The outlet of the liquid nitrogen tank group is connected to the inlet of the electric ball valve through a nitrogen pipeline, the outlet of the electric ball valve is connected to the inlet of the buffer tank after confluence through a nitrogen pipeline, the outlet of the buffer tank is connected to the inlet of the pressure reducing valve through a nitrogen pipeline, the outlet of the pressure reducing valve is connected to the inlet of the check valve through a nitrogen pipeline, the outlet of the check valve is connected to the inlet of the manual stop valve through a nitrogen pipeline, the outlet of the manual stop valve is connected to the inlet of the electric regulating valve through a nitrogen pipeline, a flow meter is provided on the intermediate pipeline between the manual stop valve and the electric regulating valve, the outlet of the electric regulating valve is connected to the nitrogen pipeline into the reactor building, and is connected to each reactor pressure vessel compartment and the main circulation compartment for loading and unloading through each branch pipe on the air supply ring pipeline.

3. According to the novel high temperature gas-cooled reactor accident mitigation measure nitrogen injection and oxygen control system of claim 1, Features: The exhaust purification system includes an iodine adsorber, a centrifugal fan, an electric air duct sealed valve, an air duct type regulating valve, an air duct type flow meter, and an exhaust duct. The two exhaust ducts are connected to the inlet of the electric air duct sealed valve after leaving the reactor building. The outlet of the electric air duct sealed valve is connected to the inlet of the iodine adsorber after converging through the exhaust duct. The outlet of the iodine adsorber is respectively connected to the inlet of the air duct type regulating valve of each branch after being diverted through the exhaust duct. The outlet of the air duct type regulating valve is connected to the inlet of the centrifugal fan through the exhaust duct. The outlet of the centrifugal fan is connected to the inlet of the electric air duct sealed valve on its branch through the exhaust duct. The outlet of the electric air duct sealed valve is connected to the chimney after converging through the exhaust duct. A duct type flow meter is provided on the exhaust duct upstream of the chimney.

4. According to the novel high temperature gas-cooled reactor accident mitigation measure nitrogen injection and oxygen control system of claim 1, Features: The nitrogen production system includes a pressure reducing valve, a check valve, a manual stop valve, a flow meter, an electric regulating valve, a complete set of nitrogen production equipment, and a nitrogen pipeline. The outlet of the complete set of nitrogen production equipment is connected to the inlet of the pressure reducing valve through a nitrogen pipeline, the outlet of the pressure reducing valve is connected to the inlet of the check valve through a nitrogen pipeline, the outlet of the check valve is connected to the inlet of the manual stop valve through a nitrogen pipeline, a flow meter is provided on the pipeline between the check valve and the manual stop valve, the outlet of the manual stop valve is connected to the inlet of the electric regulating valve through a nitrogen pipeline, and the outlet of the electric regulating valve is connected to the nitrogen pipeline to enter the reactor building.

5. According to the novel high temperature gas-cooled reactor accident mitigation measure nitrogen injection and oxygen control system of claim 1, Features: The nitrogen return system includes a manual stop valve, a flow meter, an electric control valve, a three-way connector, and a nitrogen pipeline. The nitrogen pipeline exiting the reactor building is connected to the inlet of the electric control valve. The outlet of the electric control valve is connected to the inlet of the manual stop valve through the nitrogen pipeline. A flow meter is arranged on the intermediate pipeline between the electric control valve and the manual stop valve. The outlet of the manual stop valve is connected to the inlet at one end of the three-way connector through the nitrogen pipeline. The inlet at the other end of the three-way connector is connected to the outlet of the manual stop valve. The inlet of the manual stop valve is connected to a section of pipeline for indoor air intake. A flow meter is arranged on this section of pipeline.

6. The novel high temperature gas-cooled reactor accident mitigation measure nitrogen injection and oxygen control system according to claim 4, Features: The complete set of nitrogen making equipment includes an air compressor unit, a wet air buffer tank, a drying and purifying unit, an activated carbon filter, a dry air buffer tank, a nitrogen making unit, a nitrogen process tank, a nitrogen storage tank, and a nitrogen making equipment connecting pipe. The outlet of the air compressor unit is connected to the inlet of the wet air buffer tank through the nitrogen making equipment connecting pipe, the outlet of the wet air buffer tank is connected to the inlet of the drying and purifying unit through the nitrogen making equipment connecting pipe, the outlet of the drying and purifying unit is connected to the inlet of the activated carbon filter through the nitrogen making equipment connecting pipe, the outlet of the activated carbon filter is connected to the inlet of the dry air buffer tank through the nitrogen making equipment connecting pipe, the outlet of the dry air buffer tank is connected to the inlet of the nitrogen making unit through the nitrogen making equipment connecting pipe, the outlet of the nitrogen making unit is connected to the inlet of the nitrogen process tank through the nitrogen making equipment connecting pipe, the outlet of the nitrogen process tank is connected to the inlet of the nitrogen storage tank through the nitrogen making equipment connecting pipe, and the outlet of the nitrogen storage tank is connected to the main pipe of the nitrogen making system.

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