System for LOCA accident simulation irradiation test and design method

Abstract

The invention discloses a system for LOCA accident simulation irradiation test and a design method, which are characterized in that a pressurized water reactor fuel element LOCA irradiation performance test is taken as a research object, a circulation loop and a test device are established, prototype reactor operation conditions and different accident process thermal hydraulic conditions are simulated, a fuel element LOCA irradiation simulation test is carried out, and a test result is obtained. The high-temperature and high-pressure water system is divided into three areas according to temperature and pressure, the three-stage cooling circulation system is combined with the detachable plate heat exchanger, and the number of the heat exchangers and the parameter coupling complexity among the three-stage system are reduced. The mode of combining circulation loop electric heating and in-pile device electric heating is adopted, the irradiation test thermal condition is controlled, the test power of the device is increased, the device adopts a long heat exchange flow channel, the natural circulation capacity is constructed, and the safety of the test device is improved; the invention provides a test method aiming at release working conditions of trace and massive gases and fission products, and a simulated irradiation test covering various accident working condition ranges is provided, so that the application range is wide.

Description

Technical Field

[0001] The invention belongs to the technical field of irradiation testing, and in particular relates to a system and a design method for LOCA accident simulation irradiation testing. Background Art

[0002] With the growing global demand for clean energy, commercial reactors, as an important energy supply method, have become the core goals of their development in terms of economy and safety. Therefore, research on safer new reactors and development of accident-tolerant fuels to improve the accident-tolerant performance of reactors have become important directions for the development of commercial reactors. Among design basis accidents, loss of coolant accidents (LOCA), especially small break loss of coolant accidents (SBLOCA), are considered to be the focus of in-depth research due to their possible serious consequences. A large number of overall effect tests and separation effect tests have been conducted at home and abroad for LOCA accidents of commercial pressurized water reactors to evaluate the response and performance of reactors in such accidents. However, performance irradiation tests of LOCA accidents under irradiation environments, especially under pressurized water reactor conditions, are still relatively scarce. Although test facilities such as high-temperature water environment loops have been built in China, irradiation test conditions that can fully simulate LOCA accidents have not yet been formed, which to a certain extent limits our understanding and prediction of the behavioral characteristics of reactors under extreme conditions. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a system and a design method for LOCA accident simulation irradiation test.

[0004] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is: a system for LOCA accident simulation irradiation test, including a test device and a circulation loop, the test device and the circulation loop can be openably connected; the circulation loop includes a low temperature and low pressure area, a low temperature and high pressure area and a high temperature and high pressure area, and the simulation of thermal conditions is achieved through the main circulation system, the secondary water cooling system and the tertiary cooling water system; the test device is arranged in the high temperature and high pressure area, and the test device includes a test section;

[0005] A heat exchange channel, used for heat exchange and reducing the outlet temperature, wherein the length of the heat exchange channel is greater than the test section;

[0006] The circulation loop and the test device are both connected to a radioactive product deposition auxiliary system for detecting and processing fission products.

[0007] Furthermore, the circulation loop includes: a deionized water system, which is arranged in the low-temperature and low-pressure zone and is used to produce deionized water required for chemical volume control;

[0008] A chemical volume control system is arranged in the low temperature and high pressure zone and is used to adjust and control the water chemical conditions that meet the irradiation test.

[0009] Furthermore, the test device is provided with an electric heating module, a first vapor-liquid separation module, the test section, the heat exchange flow channel, and a second vapor-liquid separation module in sequence from the bottom to the fluid outlet direction;

[0010] The outlet portion of the test output of the test device is provided with a device water outlet for collecting and treating the radioactive liquid generated during the test.

[0011] Furthermore, the circulation loop is provided with an electric heater to work in coordination with the electric heating module, specifically:

[0012] The electric heater is arranged in the circulation loop and connected to the inlet end of the test device, and is used to preheat the fluid before entering the test device;

[0013] The electric heating module is used to further heat the test section and the fluid in front of it as needed during the test.

[0014] Furthermore, the circulation loop also includes a heat exchanger group, and the inlet end of the heat exchanger group is connected to the outlet of the test device for heat exchange with the coolant during the test process.

[0015] Furthermore, the heat exchanger group includes at least two heat exchangers with different powers, and at least two of the heat exchangers are connected in parallel.

[0016] Furthermore, a detachable plate heat exchanger is arranged between the secondary cooling water system and the tertiary cooling water system.

[0017] Furthermore, the radioactive product deposition auxiliary system includes a first radioactive product deposition auxiliary system and a second radioactive product deposition auxiliary system, wherein the first radioactive product deposition auxiliary system is connected to the outlet of the test device and is used to process radioactive products generated during the test;

[0018] The second radioactive product deposition auxiliary system is connected to the circulation loop and is used to monitor and process the radioactive products that may be carried in the circulation loop.

[0019] Furthermore, a design method for LOCA accident simulation irradiation test, wherein the working conditions of the simulation irradiation test include leakage of radioactive products and leakage of no radioactive products;

[0020] When leakage of radioactive products is detected in the simulated irradiation test before the fuel damage test process is carried out, the method comprises: S11, making the temperature of the fluid entering the test device equal to the operating temperature of the pressurized water reactor through the electric heater of the circulation loop;

[0021] S12, after entering the test device, passing through the electric heating module and the first vapor-liquid separation device to enter the test sample area;

[0022] S13, after the fluid of the test device passes through the test section, it exchanges heat with the research reactor medium in the heat exchange flow channel;

[0023] S14. After exchanging heat with the research reactor medium, the gas generated in the test passes through the second vapor-liquid separation module, and is discharged to the radioactive product deposition auxiliary system along the upper part of the test device.

[0024] Further, when leakage of radioactive products is detected in the simulated irradiation test during the fuel damage test, the method comprises: S21, before the irradiation test in which fission gas is generated in the irradiation test, the circulation loop continuously cools the device;

[0025] S22, when the fuel damage simulation test process is being carried out, when the fission gas release of the first set concentration is detected, the connection between the test device and the circulation loop is cut off,

[0026] S23, the fluid in the test device passes through the electric heating module and the first vapor-liquid separation device and enters the test section;

[0027] S24, after passing through the test section, the test reagent exchanges heat with the research reactor medium in the heat exchange flow channel, generates non-condensable gas through the second vapor-liquid separation module, and is exported to the radioactive product deposition auxiliary system;

[0028] S25. The liquid exchanges heat in the test device and descends to the bottom of the test device, forming a natural circulation condition.

[0029] After adopting the above technical scheme, the present invention has the following beneficial effects compared with the prior art.

[0030] 1) The present invention provides a system and design method for LOCA accident simulation irradiation test, which can simulate the prototype reactor water chemical environment and carry out simulated accident irradiation test based on the conditions of fuel in different accident processes;

[0031] 2) The present invention innovatively divides the high-temperature and high-pressure water circuit into three sections, namely, the low-temperature and low-pressure section, the low-temperature and high-pressure section, and the high-temperature and high-pressure section. The high-temperature and high-pressure section is mainly located in the irradiation device, which reduces the difficulty of circuit design and construction. In the event of an extreme accident, the irradiation device pressure pipe can also be used to completely collect the radioactive products;

[0032] 3) The secondary water loop system and the tertiary water loop system utilize the mature detachable plate heat exchanger 106, which can greatly alleviate the parameter coupling complexity caused by the parallel connection of multiple heat exchangers in the main circulation system, and at the same time reduce the complexity of the secondary water system and the tertiary water system;

[0033] 4) The main circulation system of the present invention adopts multiple heat exchangers 105 and a detachable plate heat exchanger 106, which can meet the different power irradiation test simulations of single rod LOCA and larger rod bundle LOCA;

[0034] 5) The test device proposed in the present invention innovatively adopts an integrated design method, with a built-in long heat exchange flow channel 2, vapor-liquid separation modules 1 and 4, and an electric heating module 5. The steam-water and other environmental conditions in the device can be adjusted according to the accident test conditions to be simulated, thereby enhancing the range of conditions that can be simulated;

[0035] 6) The test device proposed in the present invention innovatively designs the top air cavity part and specifically designs the radioactive product deposition auxiliary system to construct a fuel status monitoring means under normal operating conditions and to collect and process fission gas and other products under accident conditions.

[0036] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the drawings described below are only some embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the accompanying drawings:

[0038] Figure 1 It is a schematic diagram of the structure of the present invention; a schematic diagram of a device for LOCA accident simulation irradiation test.

[0039] Description of the reference numerals: (1) Experimental device: 1. Second vapor-liquid separation module; 2. Heat exchange flow channel; 3. Test section; 4. First vapor-liquid separation module; 5. Electric heating module;

[0040] (2) Circulation loop section: 101. Test device water inlet; 102. Device water outlet; 103. Switching valve group; 104. Radioactive product deposition auxiliary system (connected to the test device gas section and the circulation loop section respectively); 105. Main heat exchanger group; 106. Removable plate heat exchanger; 107. Secondary cooling water system; 108. Tertiary cooling water system; 109. Filter; 10. Buffer tank; 111. Main circulation pump; 112. Regulator; 113. Nitrogen system; 114. Flow meter; 115. Electric heater; 116. Injection system; 117. Regenerator; 118. Booster pump; 119. Chemical volume control system water tank; 120. Chemical volume control system; 121. Deionized water circulation pump; 122. Deionized water treatment system; 123. Deionized water tank.

[0041] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0043] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0044] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] Example 1

[0046] A system for LOCA accident simulation irradiation test, including a test device and a circulation loop, the test device and the circulation loop can be connected in an openable and closed manner, the circulation loop includes a low temperature and low pressure zone, a low temperature and high pressure zone and a high temperature and high pressure zone, and the simulation of thermal conditions is achieved through a main circulation system, a secondary water cooling system and a tertiary cooling water system; the test device is arranged in the high temperature and high pressure zone, the test device includes a test section 3; a heat exchange flow channel 2 for heat exchange and reducing the outlet temperature, the length of the heat exchange flow channel 2 is greater than the test section 3, and the circulation loop and the test device are both connected to a radioactive product deposition auxiliary system for detecting and processing fission products. The present invention can accurately simulate the thermal conditions of different stages and positions in the LOCA accident through the arrangement of the low temperature and low pressure zone, the low temperature and high pressure zone and the high temperature and high pressure zone, thereby improving the accuracy and flexibility of the simulation. In addition, the coordinated work of the main circulation system, the secondary water cooling system and the tertiary cooling water system ensures the stable control and efficient simulation of the thermal conditions. This multi-level cooling system can effectively simulate the temperature changes in the accident and provide reliable environmental conditions for the test. Secondly, the length of the heat exchange channel 2 is greater than that of the test section 3. This design helps to more effectively reduce the outlet temperature, reduce heat loss during the test, and improve the accuracy and stability of the test.

[0047] In this technical solution, the patent of the present invention can handle the irradiation test of trace radioactivity and the irradiation test of large amount of radioactivity in the LOCA accident simulation test according to different process conditions of accident simulation. The main loop is disconnected and connected to the radioactive product deposition auxiliary system for processing by switching valve groups such as dose parameters, radionuclide detection, and fuel rod status detection signals. The circulation loop design is divided into three loops, which can control trace radioactivity in the main circulation system and accident condition radioactivity in the secondary cooling water system.

[0048] In this technical solution, the radioactive product deposition auxiliary system includes a first radioactive product deposition auxiliary system 104 and a second radioactive product deposition auxiliary system 124. The first radioactive product deposition auxiliary system 104 is connected to the outlet of the test device and is used to process the radioactive products generated during the test; the second radioactive product deposition auxiliary system 124 is connected to the circulation loop and is used to monitor and process the radioactive products that may be carried in the circulation loop. The first radioactive product deposition auxiliary system 104: is directly connected to the outlet of the test device and can quickly and directly process the radioactive products generated during the test. The second radioactive product deposition auxiliary system 124: is connected to the circulation loop and is specifically used to monitor and process the radioactive products that may be carried in the circulation loop; the two systems do not interfere with each other and can simultaneously and efficiently process the radioactive products in the test device and the circulation loop, thereby improving the overall processing efficiency. In addition, two independent radioactive product deposition auxiliary systems provide double protection for the safety of the system. Even if one of the systems fails or fails, the other system can still continue to work to ensure the effective treatment of radioactive products.

[0049] In this technical solution, a switching valve group 103 is provided at the connection between the test device and the circulation loop. When the fission product release and other working conditions are detected, the automatic switching valve group 103 can disconnect the circulation loop and introduce the fission products into the radioactive product deposition auxiliary system 104, while forming a connection loop with the device to collect, analyze and process the fission products.

[0050] In a feasible embodiment, the circulation loop includes: 1. A deionized water system, which is arranged in the low-temperature and low-pressure zone and is used to produce deionized water required for chemical volume regulation; 2. A chemical volume control system, which is arranged in the low-temperature and high-pressure zone and is used to regulate the water chemical conditions that meet the irradiation test. The combined use of the deionized water system and the chemical volume control system described in the present application can significantly improve the water quality and chemical condition control level of the irradiation test, and improve the quality and reliability of the test.

[0051] In a feasible embodiment, the test device is provided with an electric heating module 5, a first vapor-liquid separation module 4, the test section 3, the heat exchange channel 2, and a second vapor-liquid separation module 1 in sequence from the bottom to the outlet direction of the test output. The outlet of the test output of the test device is provided with a gas exhaust interface 102, and the gas exhaust interface 102 is connected to the radioactive product deposition auxiliary system 104 for collecting and processing the radioactive products generated during the test.

[0052] The electric heating module 5 described in the present application is located at the bottom of the test device, which can heat the test medium evenly and effectively to ensure accurate temperature control during the test. The first vapor-liquid separation module 4, located above the electric heating module 5, can timely separate the steam and liquid generated during the heating process to avoid interference of steam with subsequent test sections. The test section 3 is the core part of the test device, which is used to simulate and observe key phenomena and processes in LOCA accidents. The heat exchange flow channel 2 is located after the test section, which is used to reduce the temperature of the test output and protect subsequent equipment and systems from high temperature damage. Through the design of the heat exchange flow channel, the temperature gradient during the test can be more effectively controlled to improve the accuracy and safety of the test. The second vapor-liquid separation module 1 further separates the test output into vapor and liquid to ensure that the subsequent treatment and discharge of the medium meets safety standards and reduces the risk of diffusion of radioactive products in the environment.

[0053] In this technical solution, a gas-sealed space is reserved at the top of the test device to accommodate non-condensable gases during the experiment, and is connected to the radioactive product deposition auxiliary system and the fuel element status detection system to complete product analysis and fuel element technical status detection.

[0054] In a feasible embodiment, the circulation loop is provided with an electric heater 115 to work in conjunction with the electric heating module 5. Specifically, the electric heater 115 is provided in the circulation loop and connected to the inlet end of the test device, and is used to preheat the test reagent before entering the test device; the electric heating module 5 is used to further heat the test section 3 and the fluid before it as needed during the test.

[0055] In a feasible implementation manner, the circulation loop further includes a heat exchanger group 105, and the inlet end of the heat exchanger group 105 is connected to the outlet of the test device for heat exchange with the non-condensable gas generated during the test.

[0056] In this technical solution, the heat exchanger group 105 includes at least two heat exchangers with different powers, and at least two of the heat exchangers are connected in parallel; preferably, the heat exchanger group 105 includes three heat exchangers with different powers, and the three heat exchangers are connected in parallel.

[0057] In this technical solution, the basic process of the entire irradiation test circulation loop specifically includes: the deionized water system includes a deionized water tank 123, a deionized water circulation pump 121, and a deionized water treatment system 122. The deionized water tank 123 produces deionized water that meets the simulated irradiation test through the deionized water circulation pump 121 and the deionized water treatment system 122. After the deionized water circulation pump 121 enters the chemical volume control system to adjust the water quality, the water quality that meets the irradiation test conditions enters the buffer tank 110 of the main circulation loop through the booster pump 118. The water in the buffer tank 110 passes through the filter 109 to filter solid particles in the loop to prevent damage to the main circulation pump 111. After entering the main circulation pump 111, it passes through the flow meter 114 and the electric heater 115 and enters the test device. In the test device, it passes through the electric heating module 5 to adjust the irradiation test simulation conditions. It passes through the gas-liquid separation device 4 to control the test conditions to test the test section 3. A long heat exchange channel 2 is arranged at the outlet of the test section 3, and the upper space of the test device is used to exchange heat with the research reactor medium to reduce the outlet temperature of the test device. The non-condensable gas is separated through the vapor-liquid separation module 1, and finally flows out of the test device into the parallel main heat exchanger group 105, and returns to the inlet of the main circulation pump 111 after heat exchange.

[0058] In a feasible implementation, a detachable plate heat exchanger 106 is provided between the secondary cooling water system and the tertiary cooling water system. The detachable heat exchanger 106 can be adapted to the working conditions before the irradiation test to perform power matching, thereby reducing the number of rear-end heat exchangers. The main circulation system of the present invention adopts a plurality of main heat exchanger groups 105 and the detachable plate heat exchanger 106, which can meet the different power irradiation test simulations of single-rod LOCA and larger rod bundle LOCA.

[0059] Example 2

[0060] A design method for a LOCA accident simulation irradiation test, wherein the working conditions of the simulation irradiation test include fuel leakage and no fuel leakage; when a gas leakage is detected in the simulation irradiation test before the fuel damage test process is carried out, the method comprises: S11, making the reagent entering the test device equal to the operating temperature of the pressurized water reactor through the electric heater 115 of the circulation loop; S12, after entering the test device, passing through the electric heating module 5 and the first vapor-liquid separation device 4 to the progress test sample area; S13, after the reagent of the test device passes through the test section 3, it exchanges heat with the research reactor medium in the heat exchange flow channel 2; S14, after exchanging heat with the research reactor medium, it passes through the second vapor-liquid separation module 1, and the gas generated in the test is discharged to the radioactive product deposition auxiliary system 104 along the upper part of the test device.

[0061] A design method for a LOCA accident simulation irradiation test, wherein the working conditions of the simulation irradiation test include leakage of radioactive products and no leakage of radioactive products. When leakage of radioactive products is detected in the simulation irradiation test before a fuel damage test is performed, the method comprises: S11, making the temperature of the fluid entering the test device equal to the operating temperature of a pressurized water reactor through an electric heater (115) of a circulation loop; S12, after entering the test device, passing through an electric heating module 5 and a first vapor-liquid separation device 4 to enter a test sample area; S13, after passing through a test section 3, the fluid of the test device exchanges heat with a research reactor medium in a heat exchange flow channel 2; S14, after exchanging heat with the research reactor medium, passing through a second vapor-liquid separation module 1, and the gas generated in the test is discharged to the radioactive product deposition auxiliary system 104 along the upper part of the test device.

[0062] In this technical solution, when gas leakage is detected in the simulated irradiation test during the fuel damage test, the method includes: S21, before the irradiation test to generate fission gas, the circulation loop continues to cool the device; S22, when the fuel damage simulation test is in progress, when the fission gas release of the first set concentration is detected, the connection between the test device and the circulation loop is cut off, S23, the reagent in the test device passes through the electric heating module 5 and the first vapor-liquid separation device 4 to enter the test section 3; S24, after the test reagent passes through the test section 3, it exchanges heat with the research reactor medium in the heat exchange flow channel 2, generates non-condensable gas through the second vapor-liquid separation module 1, and is exported to the radioactive product deposition auxiliary system 104; S25, the liquid exchanges heat in the test device and descends to the bottom of the test device, forming a natural circulation condition. Limited by the large heat exchange capacity required by the natural circulation device to ensure safety, this working condition mainly conducts a single-rod LOCA simulated irradiation test.

[0063] In a feasible implementation, for the irradiation test condition without fission products and a small amount of hydrogen, that is, the simulation test in which the simulated fuel is not damaged: the pressure water reactor inlet temperature condition is reached through the circulation loop electric heating system, and the simulated test condition is reached through the electric heating module 5 in the device. After passing through the test section, heat is exchanged with the research reactor medium in the long heat exchange flow channel; after heat exchange by the main heat exchanger 105, it returns to the test device through the main circulation pump 111, and the radioactive product deposition auxiliary system is still put into use, and the gas part of the test device is connected to monitor and collect fission gas, and the circulation loop part is connected to collect, analyze and process the remaining fission products as safety signal input to ensure the safe operation of the irradiation test. At this time, the main circulation loop is the heat sink of the entire device. Since the loop system has a strong cooling capacity, this condition mainly conducts a large number of rod bundle tests, and only a trace amount of fission products are released. For the condition of a large number of product releases, shielding protection and other designs can be completed for the loop system to ensure effective control of the product, and the circulation loop part has the possibility of an expandable design that can accommodate the simulation of a large number of radioactive product release conditions.

[0064] The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical content suggested above without departing from the scope of the technical solution of the present invention. The implementation scheme in the above embodiment can also be further combined or replaced. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the solution of the present invention.

Claims

1. A system for LOCA accident simulation irradiation test, characterized in that: It includes a test device and a circulation loop, wherein the test device and the circulation loop can be connected in an openable and closable manner; The circulation loop includes a low-temperature and low-pressure area, a low-temperature and high-pressure area, and a high-temperature and high-pressure area, and the simulation of thermal conditions is achieved through the main circulation system, the secondary water cooling system, and the tertiary cooling water system; The test device is arranged in the high temperature and high pressure zone, and comprises a test section (3); A heat exchange channel (2) for exchanging heat and reducing the outlet temperature, wherein the length of the heat exchange channel (2) is greater than that of the test section (3); The circulation loop and the test device are both connected to a radioactive product deposition auxiliary system for detecting and processing fission products.

2. The system for LOCA accident simulation irradiation test according to claim 1, characterized in that: The circulation loop comprises: A deionized water system, which is arranged in the low-temperature and low-pressure zone and is used to produce deionized water required for chemical volume regulation; A chemical volume control system is arranged in the low temperature and high pressure zone and is used to adjust and control the water chemical conditions that meet the irradiation test.

3. The system for LOCA accident simulation irradiation test according to claim 2, characterized in that: The test device is provided with an electric heating module (5), a first vapor-liquid separation module (4), the test section (3), the heat exchange flow channel (2), and a second vapor-liquid separation module (1) in sequence from the bottom to the fluid outlet; The test output outlet of the test device is provided with a device water outlet (102) for collecting and treating the radioactive liquid generated during the test.

4. The system for LOCA accident simulation irradiation test according to claim 3, characterized in that: The circulation loop is provided with an electric heater (115) which works in coordination with the electric heating module (5), specifically: The electric heater (115) is arranged in the circulation loop and connected to the inlet end of the test device, and is used to preheat the fluid before entering the test device; The electric heating module (5) is used to further heat the test section (3) and the fluid before it as required during the test process.

5. The system for LOCA accident simulation irradiation test according to claim 4, characterized in that: The circulation loop further comprises a heat exchanger group (105), the inlet end of the heat exchanger group (105) being connected to the outlet of the test device for exchanging heat with the coolant during the test process.

6. The system for LOCA accident simulation irradiation test according to claim 5, characterized in that: The heat exchanger group (105) includes at least two heat exchangers with different powers, and at least two of the heat exchangers are connected in parallel.

7. The system for LOCA accident simulation irradiation test according to claim 1, characterized in that: A detachable plate heat exchanger (106) is arranged between the secondary cooling water system and the tertiary cooling water system.

8. The system for LOCA accident simulation irradiation test according to claim 1, characterized in that: The radioactive product deposition auxiliary system comprises a first radioactive product deposition auxiliary system (104) and a second radioactive product deposition auxiliary system (124); the first radioactive product deposition auxiliary system (104) is connected to the outlet of the test device and is used to process radioactive products generated during the test; The second radioactive product deposition auxiliary system (124) is connected to the circulation loop and is used to monitor and process radioactive products that may be carried in the circulation loop.

9. A design method for LOCA accident simulation irradiation test, characterized in that: The method is based on the system for LOCA accident simulation irradiation test as described in claims 1 to 8 above, The working conditions of the simulated irradiation test include leakage of radioactive products and leakage of no radioactive products; When leakage of radioactive products is detected in the simulated irradiation test before the fuel damage test process is carried out, the method comprises: S11, using the electric heater (115) of the circulation loop to make the temperature of the fluid entering the test device equal to the operating temperature of the pressurized water reactor; S12, after entering the test device, passing through the electric heating module (5) and the first vapor-liquid separation device (4) to enter the test sample area; S13, after the fluid of the test device passes through the test section (3), it exchanges heat with the research reactor medium in the heat exchange flow channel (2); S14, after heat exchange with the research reactor medium, the gas generated in the test passes through the second vapor-liquid separation module (1), and is discharged to the radioactive product deposition auxiliary system (104) along the upper part of the test device.

10. The design method for LOCA accident simulation irradiation test according to claim 9, characterized in that: When leakage of radioactive products is detected in the simulated irradiation test during the fuel damage test, the method comprises: S21, before the irradiation test to produce fission gas, the circulation loop continues to cool the device; S22, when the fuel damage simulation test process is being carried out, when the fission gas release of the first set concentration is detected, the connection between the test device and the circulation loop is cut off, S23, the fluid in the test device passes through the electric heating module (5) and the first vapor-liquid separation device (4) and enters the test section (3); S24, after passing through the test section (3), the test reagent exchanges heat with the research reactor medium in the heat exchange flow channel (2), generates non-condensable gas through the second vapor-liquid separation module (1), and guides the non-condensable gas to the radioactive product deposition auxiliary system (104); S25. The liquid exchanges heat in the test device and descends to the bottom of the test device, forming a natural circulation condition.

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