Neutron source activation-based corrosion product source item deposition characteristic online monitoring device and method

Abstract

The invention discloses a corrosion product source item deposition characteristic on-line monitoring device and method based on neutron source activation. The corrosion product source item deposition characteristic on-line monitoring device comprises a water storage tank, a corrosion sample activation test section, a simulation reactor core test section, a main pipeline heat pipe section simulation body, a steam generator simulation body and a main pipeline cold pipe section simulation body. A neutron source is arranged in the corrosion sample activation test section and is used for performing irradiation activation on a corrosion product in a test solution; and gamma-ray energy disperse spectrums D1, D2, D3 and D4 are respectively arranged beside the simulation reactor core test section, the main pipeline heat pipe section simulation body, the steam generator simulation body and the main pipeline cold pipe section simulation body. According to the method, deposition behaviors of corrosion products in a pressurized water reactor primary loop coolant after being activated by neutrons on the surfaces of a fuel element, a steam generator heat transfer pipe and a main pipeline are simulated in a laboratory environment, and deposition radioactive characteristics of the corrosion products on the surfaces of all parts after a neutron source is activated are detected on line through a gamma energy disperse spectroscopy; and online measurement of source item deposition characteristics of surface corrosion products of different parts is realized.

Description

Technical Field

[0001] This invention relates to the field of radiation source term analysis technology, and more specifically, to an online monitoring device and method for the deposition characteristics of corrosion product source terms based on neutron source activation. Background Technology

[0002] Radioactive source term calculation software is an important means of determining the radiation source term and dose of nuclear power plants. By simulating the physicochemical processes such as the material exchange between coolant and deposits, the transport effect of coolant on its carried materials, and the activation effect under neutron irradiation, it describes the generation, transport, activation, and deposition effects of major corrosion products in the system, obtaining the distribution of major corrosion products and their activation products within the system. The software describes the deposition rate of corrosion products on the surfaces of primary loop system components such as fuel elements, steam generators, and main pipes, as well as the distribution coefficients of corrosion products on the surfaces of each component, which are obtained through corrosion product deposition experiments. Currently, this method mainly simulates the actual water quality, temperature, pressure, and flow rate conditions of pressurized water reactors through an external dynamic water test loop. By setting up primary loop main equipment and components such as fuel elements, steam generators, and main pipes in the loop, the deposition characteristics and laws of primary loop corrosion products are studied, obtaining the corrosion product deposition characteristic parameters of the primary loop main equipment and components. However, this method requires dissection and analysis of the simulated test components such as fuel elements, steam generators, and main pipes after the experiment, making it difficult to obtain the primary loop corrosion product deposition characteristic parameters of pressurized water reactors online during the experiment.

[0003] The shutdown process of a pressurized water reactor (PWR) involves significant changes in physicochemical conditions. Specifically, the coolant temperature and pH value decrease. When the coolant temperature drops to 80°C, hydrogen peroxide is injected, causing the primary coolant to change from a reducing to an oxidizing state. This accelerates the dissolution of activated corrosion products deposited on the core and the inner surfaces of the primary circuit equipment. Quantitatively determining the deposition characteristics of primary circuit corrosion products during shutdown is crucial for the accuracy and reliability of radiation source term distribution analysis in radioactive source term software during shutdown. Currently, there are no experimental devices or methods for online measurement of corrosion product source term deposition, leaving research on the deposition behavior of major primary circuit equipment and components during shutdown in a state of flux.

[0004] In view of the above, this application is hereby submitted. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an online monitoring device and method for corrosion product source term deposition characteristics based on neutron source activation. In a laboratory environment, the device simulates the deposition behavior of corrosion products in the primary coolant of a pressurized water reactor (PWR) after neutron activation on the surfaces of fuel elements, steam generator heat transfer tubes, and main pipelines. The device utilizes a neutron source to irradiate and activate the corrosion products in the coolant. A gamma-ray spectrometer is used to detect the radioactive characteristics of the corrosion products deposited on the surfaces of various components after neutron source activation. Based on changes in gamma-ray intensity, the deposition rate of corrosion products on the surfaces of major equipment and components in the primary loop of the PWR and the deposition distribution coefficient of corrosion products on each component surface can be obtained online. This enables online measurement of the source term deposition characteristics of corrosion products on different component surfaces. It can be used for continuous and online acquisition of corrosion product deposition data at different locations under shutdown and variable power operation conditions to correct the theoretical calculation model of corrosion product source terms.

[0006] This invention is achieved through the following technical solution: In a first aspect, the present invention provides an online monitoring device for the deposition characteristics of corrosion product source terms based on neutron source activation, comprising a water tank, a corrosion sample activation test section, a simulated core test section, a main pipeline hot pipe section simulator, a steam generator simulator, and a main pipeline cold pipe section simulator connected in sequence to form a loop; The water storage tank is used to store the test solution and to circulate the test solution into the corrosion sample activation test section; A neutron source is provided in the corrosion sample activation test section, which is used to irradiate and activate the corrosion products in the test solution flowing through the corrosion sample activation test section. The simulated core test section, the main pipeline hot pipe section simulator, the steam generator simulator, and the main pipeline cold pipe section simulator are used to simulate the deposition of corrosion products on the surfaces of fuel elements, steam generators, and main pipelines in the primary loop of a pressurized water reactor, respectively. Next to the simulated reactor core test section, the main pipeline hot pipe section simulator, the steam generator simulator, and the main pipeline cold pipe section simulator, gamma-ray spectrometers D1, D2, D3, and D4 are respectively installed to monitor the radioactive characteristics of the activated corrosion products deposited on the surface.

[0007] This invention simulates the deposition behavior of corrosion products in the primary coolant of a pressurized water reactor (PWR) on the surfaces of fuel elements, steam generator heat transfer tubes, and main pipelines after neutron activation in a laboratory environment. It utilizes a neutron source to irradiate and activate the corrosion products in the coolant, and then uses a gamma-ray spectrometer to detect the radioactive characteristics of the corrosion products deposited on the surfaces of various components after neutron activation. Based on changes in gamma-ray intensity, the deposition rate of corrosion products on the surfaces of major equipment and components in the primary loop of the PWR and the deposition distribution coefficient of corrosion products on each component surface can be obtained online. This enables online measurement of the source term deposition characteristics of corrosion products on different component surfaces. It can be used for continuous, online acquisition of corrosion product deposition data at different locations under shutdown and variable power operation conditions to correct the theoretical calculation model of corrosion product source terms.

[0008] In one specific embodiment, the corrosion sample activation test section has a cylindrical ring structure, and a neutron source, such as an Am-Be neutron source or a Cf-252 neutron source, is placed in its internal cavity; the neutron source irradiates the corrosion products in the corrosion product activation test section to activate the corrosion products in the test solution.

[0009] In one specific embodiment, a radiation shield is provided outside the corrosion sample activation test section to reduce the background interference of n and gamma rays in the corrosion sample activation test section on the gamma measurement, thereby improving the measurement effect.

[0010] In one specific embodiment, the simulated reactor core test section is equipped with a fuel element simulator. The outer diameter and flow channel structure of the fuel element simulator are the same as those of a commercial pressurized water reactor nuclear power plant fuel element. The outer shell is made of fuel cladding zirconium alloy. An electric heating element is arranged inside the fuel element simulator to simulate the heating of the fuel element and realize the simulation of the surface boiling phenomenon of the fuel element.

[0011] In one specific embodiment, both the main pipeline hot pipe section simulator and the main pipeline cold pipe section simulator are made of the same material as the pressurized water reactor primary loop main pipeline, and both are equipped with pipeline heat tracing devices on their outer sides.

[0012] In one specific embodiment, heat transfer tubes are arranged inside the steam generator simulator, and test solution flows inside the heat transfer tubes while cooling oil flows outside.

[0013] The steam generator is equipped with a secondary cooling system, and the cooling oil is connected to the secondary cooling system. The secondary cooling system includes an oil cooler, a cooling oil circulation pump, a cooling oil tank, and a water cooler. The test solution flowing in the heat transfer tube is cooled by first cooling with oil and then cooling with water. The heat of the test solution in the steam generator is removed by the cooling oil, and then the heat of the cooling oil is removed by the cooling water, so as to achieve heat exchange and maintain the thermal balance of the test circuit.

[0014] In one specific embodiment, a pressure regulator is connected in parallel to the steam generator simulator. One outlet of the steam generator simulator is connected to the cold pipe section simulator of the main pipeline, and the other outlet is connected to the inlet of the pressure regulator through the spray valve V101. The outlet of the pressure regulator and the outlet of the hot pipe section simulator of the main pipeline are merged into one pipeline and then connected to the inlet of the steam generator simulator. The pressure regulator is a steam pressure regulator used to control the pressure of the main test circuit.

[0015] In one specific implementation, one outlet of the main pipeline cold pipe section simulator is connected to the inlet of the corrosion product activation test section, and the other outlet is connected to the sampling cooler; the outlet of the sampling cooler is connected to the water storage tank through a pipeline, and a sampling branch is set in the pipeline between the sampling cooler and the water storage tank, and the sampling branch is controlled by a manual shut-off valve V11.

[0016] In one specific embodiment, the water storage tank has an inlet, a return outlet, and an exhaust outlet at the top, and a drain outlet, a water outlet, and an air inlet at the bottom. The air inlet of the water storage tank is connected to a gas cylinder via a pipeline for introducing gas into the water storage tank to adjust the dissolved gas concentration of the test solution. The exhaust outlet of the water storage tank is connected to a bubbling indicator for observing the introduction of high-purity gas. The gas cylinders include hydrogen, nitrogen, and oxygen cylinders. Manual shut-off valves V1, V2, and V3 are respectively installed between the hydrogen, nitrogen, and oxygen cylinders and the water storage tank; a manual shut-off valve V4 is installed between the bubbling indicator 4 and the water storage tank 5.

[0017] In one specific embodiment, a water supply pump and a circulation pump are sequentially installed between the water storage tank and the corrosion product activation test section. The inlet of the water supply pump is connected to the water storage tank via a pipeline, and the outlet of the water supply pump is connected to a water chemistry online monitoring instrument and an ion purification resin column arranged in parallel. The water chemistry online monitoring instrument includes a dissolved oxygen online monitor, a dissolved hydrogen online monitor, and a pH online monitor. The ion purification resin column includes a boron-containing purification resin column and a lithium-type purification resin column.

[0018] In one specific embodiment, the inlet of the water chemistry online monitoring instrument is equipped with a manual shut-off valve V5, and the outlet is connected to the flow meter F1 and the water storage tank in sequence via pipelines; the inlet of the ion purification resin column is equipped with a manual shut-off valve V6, and the outlet is connected to the flow meter F2 and the water storage tank in sequence via pipelines.

[0019] The water pump provides power to the test solution in the water storage tank, so that it flows to the water chemistry online monitoring instrument and the ion purification resin column respectively, so as to realize the online monitoring of the water chemistry parameters of the test solution and the purification of the test solution; by opening or closing the manual shut-off valves V5 and V6, the flow path of the solution can be controlled. The control methods of different flow paths are as follows: (1) close the manual shut-off valve V6 and open the manual shut-off valve V5, so as to control the solution to flow through the dissolved oxygen online monitoring instrument, the dissolved hydrogen online monitoring instrument, and the pH online monitoring instrument in sequence, without passing through the boron-type purification resin column and the lithium-type purification resin column, so as to realize the online monitoring of the water chemistry parameters of the test solution; (2) open the manual shut-off valves V5 and V6, so as to control the solution to flow through the water chemistry online monitoring instrument and the ion purification resin column respectively, so as to realize the online monitoring of the water chemistry parameters of the test solution and the purification of the test solution.

[0020] In one specific embodiment, the system also includes a dosing tank, which injects boric acid and lithium hydroxide solution, hydrogen peroxide solution, or corrosion product solution into the test circuit via a dosing pump to adjust the boron concentration, lithium concentration, and hydrogen peroxide concentration of the test solution.

[0021] The outlet pipes of the chemical dosing pump and the feedwater pump are combined into one pipeline, with a manual shut-off valve V10 installed between them. Then, it is connected to the inlet of the circulation pump. The circulation pump is a shielded pump with an adjustable frequency, which provides power for the flow of the test solution. Subsequently, it is connected in sequence to the neutron activation system, the simulated reactor core test section, the main pipeline hot pipe section simulator, the steam generator simulator, and the main pipeline cold pipe section simulator, and finally returns to the circulation pump to form the main test loop.

[0022] In one specific embodiment, the dosing tank includes a boron-lithium solution storage tank, a hydrogen peroxide solution storage tank, and a corrosion product solution storage tank. Manual shut-off valves V7, V8, and V9 are respectively installed between the boron-lithium solution storage tank, the hydrogen peroxide solution storage tank, the corrosion product solution storage tank, and the dosing pump.

[0023] Secondly, the present invention provides a monitoring method for the above-mentioned online monitoring device for the deposition characteristics of corrosion products based on neutron source activation, comprising the following steps: S1, Install the fuel element simulator in the simulated reactor core test section; S2, inject deionized water into the water storage tank, start the water supply pump, and inject boric acid, lithium hydroxide and corrosion product solution into the circuit through the dosing pump to adjust the chemical parameters of the test solution to the target value; S3, turn on the voltage regulator electric heating switch and adjust the test circuit pressure to the target value; start the fuel element simulator heating power supply; turn on the cooling oil circulation pump and adjust the test circuit coolant temperature to the target range; S4, turn on the gamma spectrometer D1-D4 to continuously measure the fuel element simulator, steam generator simulator, main pipeline hot pipe section simulator, and main pipeline cold pipe section simulator, obtain the radioactive ray energy and corresponding intensity of the activated corrosion product deposited on the surface of each component online, and analyze the element types and activities of the corrosion product deposits.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The online monitoring device and method for corrosion product source term deposition characteristics based on neutron source activation provided in this embodiment of the invention simulates the deposition behavior of corrosion products in the primary coolant of a pressurized water reactor after neutron activation on the surfaces of fuel elements, steam generator heat transfer tubes, and main pipelines in a laboratory environment. The corrosion products in the coolant are irradiated and activated using a neutron source, and the radioactive characteristics of the corrosion products deposited on the surfaces of each component after neutron source activation are detected online using a gamma-ray spectrometer. Based on the changes in gamma-ray intensity, the deposition rate of corrosion products on the surfaces of the main equipment and components of the primary circuit of the pressurized water reactor and the deposition distribution coefficient of corrosion products on the surfaces of each component can be obtained online. This realizes the online measurement of the source term deposition characteristics of corrosion products on the surfaces of different components. It can be used for continuous and online acquisition of corrosion product deposition data at different locations under shutdown conditions and variable power operation conditions to correct the theoretical calculation model of corrosion product source term. 2. The online monitoring device and method for corrosion product source term deposition characteristics based on neutron source activation provided in this embodiment of the invention uses radioactive isotope tracing to carry out corrosion product deposition experiments. The gamma-ray energy spectrometer used to detect the radioactive characteristics of the sediment has the advantage of a low detection limit. Compared with conventional off-pile experiments, a corrosion product addition method (low concentration) that is closer to the actual situation inside the pile can be used to carry out simulation experiments, and the test conditions are more representative. 3. The online monitoring device and method for corrosion product source term deposition characteristics based on neutron source activation provided in this embodiment of the invention can dynamically adjust the temperature, pressure and water chemical parameters of the test solution according to the requirements during the experiment, so as to realize the function of online determination of corrosion product deposition characteristics under different coolant chemical parameters (pH value, dissolved oxygen concentration, dissolved hydrogen concentration), different thermal parameters (temperature, pressure), and different material properties (alloy composition, processing technology and surface state of corrosion sample), thus broadening the research scope; 4. The online monitoring device and method for corrosion product source term deposition characteristics based on neutron source activation provided in this embodiment of the invention are low in cost, full in function, flexible in operating conditions, and have good controllability. They are suitable for conducting experimental research on influencing factors and have good application prospects. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the overall structure and flow of the online monitoring device provided in an embodiment of the present invention; Figure 2 A flowchart illustrating the secondary cooling system structure of a steam generator simulator provided in an embodiment of the present invention.

[0027] The attached diagram shows the markings and corresponding component names: 1-Hydrogen cylinder; 2-Nitrogen cylinder; 3-Oxygen cylinder; 4-Bubbling indicator; 5-Water storage tank; 6-Feed water pump; 7-Dissolved hydrogen online monitor; 8-Dissolved oxygen online monitor; 9-pH online monitor; 10-Boron-type purification resin column; 11-Lithium-type purification resin column; 12-Boric acid solution storage tank; 13-Hydrogen peroxide solution storage tank; 14-Corrosion product solution storage tank; 15-Dosing pump; 16-Circulation pump; 17-Neutron source; 18-Corrosion product activation test section; 19-Radiation shield; 20-Simulated core test section; 21-Fuel element simulator; 22-Main pipeline hot pipe section simulator; 23-Press regulator; 24-Steam generator simulator; 25-Main pipeline cold pipe section simulator; 26-Sampling cooler; 27-Oil cooler; 28-Cooling oil circulation pump; 29-Cooling oil tank; 30-Water cooler. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0029] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0030] Throughout this specification, references to “an embodiment,” “an example,” or “an example” mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases “an embodiment,” “an example,” “an example,” or “an example” appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0031] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0032] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0033] Example 1 like Figure 1 and Figure 2As shown, this embodiment of the invention provides an online monitoring device for the deposition characteristics of corrosion products based on neutron source activation, including a water storage tank 5, a feedwater pump 6, an online water chemistry monitoring instrument, an ion purification resin column, a dosing tank, a dosing pump 15, a circulation pump 16, a neutron activation system, a simulated reactor core test section 20, a fuel element simulator 21, a main pipeline hot pipe section simulator 22, a pressurizer 23, a steam generator simulator 24, a main pipeline cold pipe section simulator 25, a sampling cooler 26, and a gamma-ray spectrometer.

[0034] The top of the water storage tank 5 is equipped with an inlet, a return outlet, and an exhaust outlet, while the bottom is equipped with a drain outlet, a water outlet, and an air inlet. The air inlet is connected to hydrogen cylinder 1, nitrogen cylinder 2, and oxygen cylinder 3 via pipelines. Manual shut-off valves V1, V2, and V3 are respectively installed between hydrogen cylinder 1, nitrogen cylinder 2, oxygen cylinder 3 and water storage tank 5. The exhaust outlet is connected to a bubbling indicator 4 for observing the introduction of high-purity gas. A manual shut-off valve V4 is installed between the bubbling indicator 4 and water storage tank 5. The dissolved oxygen concentration of the test solution is adjusted by introducing high-purity nitrogen or oxygen into the water storage tank 5, and the dissolved hydrogen concentration is adjusted by introducing hydrogen.

[0035] The inlet of the water pump 6 is connected to the outlet of the water storage tank 5 via a pipeline. The outlet is connected to the online water chemistry monitoring instruments (including the online dissolved oxygen monitor 7, the online dissolved hydrogen monitor 8, and the online pH monitor 9) and the ion purification resin column (including the boron-type purification resin column 10 and the lithium-type purification resin column 11). The online water chemistry monitoring instruments are connected to the flow meter F1 and the water storage tank 5 via pipelines, and a manual shut-off valve V5 is installed at the inlet. A manual shut-off valve V6 is installed at the inlet of the ion purification resin column, and the outlet is connected to the flow meter F2 and the water storage tank via a pipeline. The online water chemistry monitoring instruments and the ion purification resin column are connected in parallel.

[0036] The water pump 6 provides power to the test solution in the water storage tank 5, so that it flows to the water chemistry online monitoring instrument and the ion purification resin column respectively, so as to realize the online monitoring of the water chemistry parameters of the test solution and the purification of the test solution; by opening or closing the manual shut-off valves V5 and V6, the flow path of the solution can be controlled. The control methods of different flow paths are as follows: (1) close the manual shut-off valve V6 and open the manual shut-off valve V5, so that the solution flows through the dissolved oxygen online monitoring instrument 7, the dissolved hydrogen online monitoring instrument 8, and the pH online monitoring instrument 9 in sequence, without passing through the boron-type purification resin column 10 and the lithium-type purification resin column 11, so as to realize the online monitoring of the water chemistry parameters of the test solution; (2) open the manual shut-off valves V5 and V6, so that the solution flows through the water chemistry online monitoring instrument and the ion purification resin column respectively, so as to realize the online monitoring of the water chemistry parameters of the test solution and the purification of the test solution.

[0037] The dosing tanks include a boron-lithium solution storage tank 12, a hydrogen peroxide solution storage tank 13, and a corrosion product solution storage tank 14. Each tank has an inlet at the top and a drain and outlet at the bottom to maximize the emptying of any remaining solution in each tank. The boron-lithium solution storage tank 12 stores boric acid and lithium hydroxide solution, the hydrogen peroxide solution storage tank 13 stores hydrogen peroxide solution, and the corrosion product solution storage tank 14 stores corrosion product solution. The boron-lithium solution storage tank 12, hydrogen peroxide solution storage tank 13, and corrosion product solution storage tank 14 are connected in parallel and finally connected to the dosing pump 15. Manual shut-off valves V7, V8, and V9 are respectively installed between each tank and the dosing pump 15. The dosing pump 15 injects boric acid and lithium hydroxide solution, hydrogen peroxide solution, or corrosion product solution into the test loop to adjust the boron concentration, lithium concentration, and hydrogen peroxide concentration of the test solution, which is used to simulate changes in water chemical parameters during power operation or reactor shutdown.

[0038] The outlet pipes of the dosing pump 15 and the water supply pump 6 are combined into one pipe, which is then connected to the inlet of the circulation pump 16. The circulation pump is an adjustable frequency shielded pump that provides power for the flow of the test solution.

[0039] The inlet of the corrosion product activation test section 18 is connected to the circulating pump 16, and the outlet is connected to the inlet of the simulated core test section 20 via flow meter F3. The corrosion product activation test section 18 has a cylindrical ring structure, and an isotopic neutron source 17, such as an Am-Be neutron source or a Cf-252 neutron source, is placed in the hole inside the cylindrical ring. The neutron source 17 irradiates the corrosion products in the corrosion product activation test section 18 to activate the corrosion products in the test solution. A radiation shield 19 is set outside the corrosion sample activation test section 18 to reduce the background interference of n and gamma rays in the corrosion sample activation test section on the gamma measurement, so as to improve the measurement effect.

[0040] Multiple fuel element simulators 21 are loaded inside the simulated core test section 20. The outer diameter and flow channel structure of the fuel element simulators 21 are the same as those of fuel elements in commercial pressurized water reactor nuclear power plants, and the outer shell is made of fuel cladding zirconium alloy. The heating of the fuel element is simulated by arranging electric heating elements inside the fuel element simulators 21, thereby simulating the boiling phenomenon of the fuel element surface. A gamma-ray spectrometer D1 is set up next to the simulated core test section 20 to measure the radioactivity characteristics of the activated corrosion products deposited on the fuel element simulators 21. Based on the changes in gamma-ray energy and intensity, the deposition characteristics of corrosion products on the surface of the fuel element are obtained online.

[0041] The inlet of the main pipeline heat pipe section simulator 22 is connected to the outlet of the simulated reactor core test section 20. The main pipeline heat pipe section simulator 22 is made of commercial pressurized water reactor nuclear power plant primary loop main pipeline material and a pipeline heat tracing device is installed on the outside. A gamma-ray spectrometer D2 is installed next to the main pipeline heat pipe section simulator 22 to monitor the radioactivity characteristics of the activated corrosion products deposited on the surface of the main pipeline heat pipe section simulator 22 online.

[0042] The inlet of the steam generator simulator 24 is connected to the outlet of the main pipeline heat pipe section simulator 22. Heat transfer tubes are arranged inside the steam generator simulator 24, and the materials used to manufacture the heat transfer tubes are the same as those used in commercial pressurized water reactor nuclear power plants. The test solution flows inside the heat transfer tubes of the steam generator simulator 24, and the cooling oil flows outside. The cooling oil is connected to the secondary cooling system, which consists of an oil cooler 27, a cooling oil circulation pump 28, a cooling oil tank 29, and a water cooler 30. The test solution flowing inside the heat transfer tube is cooled by first cooling with oil and then cooling with water. The heat of the test solution in the steam generator simulator 24 is removed by the cooling oil, and the heat of the cooling oil is removed by the cooling water, thus achieving heat exchange and maintaining the thermal balance of the test loop.

[0043] A gamma-ray spectrometer D3 is installed next to the steam generator simulator 24 to monitor the radioactivity characteristics of the activated corrosion products deposited on the heat transfer tubes inside the steam generator simulator 24.

[0044] The outlet of the steam generator simulator 24 is divided into two paths. One path connects to the main pipeline cold pipe section simulator 25, and the other path connects to the pressure regulator 23 through the spray valve V101. The pressure regulator 23 is a steam pressure regulator used to control the pressure of the test circuit. The outlet of the pressure regulator 23 and the outlet of the main pipeline hot pipe section simulator 22 are merged into one pipeline and then connected to the inlet of the steam generator simulator 24.

[0045] The main pipeline cold pipe section simulator 25 is made of the same material used for the primary loop main pipeline of a commercial pressurized water reactor nuclear power plant, and a pipeline heat tracing device is installed on the outside. A gamma-ray spectrometer D4 is installed next to the main pipeline cold pipe section simulator 25 to monitor the radioactivity characteristics of the activated corrosion products deposited on the surface of the main pipeline hot pipe section simulator 22 online.

[0046] The outlet of the main pipeline cold pipe section simulator 25 is divided into two paths: one path returns to the inlet of the circulating pump 16, and the other path is connected to the sampling cooler 26. The outlet of the sampling cooler 26 is connected to the water storage tank 5 through a pipeline. A sampling branch is set in the pipeline between the sampling cooler 26 and the water storage tank 5. The sampling branch is controlled by a manual shut-off valve V11.

[0047] Example 2 This invention provides an online monitoring method for the source term deposition characteristics of corrosion products based on neutron source activation, comprising the following steps: S1, Install the fuel element simulator 21 in the simulated reactor core test section 20; S2, inject deionized water into the water storage tank 5, start the water supply pump 6, and inject boric acid, lithium hydroxide and corrosion product solution into the circuit through the dosing pump 15 to adjust the concentration of boron, lithium and corrosion products in the test solution to the target value, specifically: (1) When the boron concentration or lithium concentration is lower than the target value range, open the manual shut-off valve V7 to inject high concentration boric acid or lithium hydroxide solution. After the test solution is fully circulated and mixed, open the manual shut-off valve V11 of the sampling branch to take the test solution for boron or lithium concentration detection; (2) When the boron concentration or lithium concentration is higher than the target value range, inject deionized water through the inlet of the water storage tank 5. After the test solution is fully circulated and mixed, open the manual shut-off valve V11 of the sampling branch to take the test solution for boron or lithium concentration detection; (3) Perform (1) or (2) according to the boron concentration or lithium concentration obtained by sampling detection. Until the boron and lithium concentrations are within the target range; (4) Prepare a boron-lithium solution containing a quantitative concentration of corrosion products in the corrosion product solution storage tank 14 (the boron and lithium concentrations are within the target range), open the manual shut-off valve V9 to inject the test solution into the test circuit, and after the test solution is fully circulated and mixed, open the manual shut-off valve V11 of the sampling branch to take the test solution for corrosion product concentration detection; (5) When the corrosion product concentration is lower than the target range, repeat (4) until the corrosion product concentration is within the target range; (6) When the corrosion product concentration is higher than the target range, open the manual shut-off valve V6 to allow the test solution to flow through the boron-type ion purification resin column 10 and the lithium-type ion purification resin column 11, open the manual shut-off valve V11 of the sampling branch to take the test solution for corrosion product concentration detection until the corrosion product concentration is within the target range. S3, open the manual shut-off valve V5, monitor the dissolved hydrogen concentration and dissolved oxygen concentration of the test solution, and adjust the dissolved hydrogen concentration and dissolved oxygen concentration of the test solution to the target value by passing hydrogen, oxygen or nitrogen. Specifically: (1) When the dissolved hydrogen concentration is lower than the target value range, open the manual shut-off valve V1 to pass high-purity hydrogen until the dissolved hydrogen concentration is within the target value range, and then close the manual shut-off valve V1; (2) When the dissolved hydrogen concentration is higher than the target value range, open the manual shut-off valve V2 to pass high-purity nitrogen until the dissolved hydrogen concentration is within the target value range, and then close the manual shut-off valve V2; (3) When the dissolved oxygen concentration is lower than the target value range, open the manual shut-off valve V3 to pass high-purity oxygen until the dissolved oxygen concentration is within the target value range, and then close the manual shut-off valve V3; (4) When the dissolved oxygen concentration is higher than the target value range, open the manual shut-off valve V2 to pass high-purity nitrogen until the dissolved oxygen concentration is within the target value range, and then close the manual shut-off valve V2. S4, turn on the electric heating switch of the voltage regulator 23, gradually increase the pressure of the test circuit, and adjust the system pressure to the target value in coordination with the spray valve V101; adjust the frequency of the circulation pump 16, and adjust the coolant flow rate of the test circuit to be within the target value range; start the heating power supply of the fuel element simulator 21, turn on the cooling oil circulation pump 28, and adjust the heating power and the cooling oil flow rate in the secondary cooling system to raise the temperature of the coolant in the test circuit to the target value range; S5, turn on the gamma-ray spectrometer D1-D4 to continuously measure the fuel element simulator 20, steam generator simulator 24, main pipeline hot pipe section simulator 22 and main pipeline cold pipe section simulator 25, obtain the radioactive ray energy and corresponding intensity of the corrosion product deposit layer on the surface of each component online, and analyze the element types and activities of the corrosion product deposit. S6, the temperature of the test solution is adjusted by regulating the heating power of the fuel element simulator 21 and the cooling oil flow rate in the secondary cooling system of the steam generator simulator 24; the pressure is adjusted by regulating the heating power of the pressure regulator 23; the concentrations of boron, lithium, and hydrogen peroxide are adjusted by adding chemical reagents to the boron-lithium solution storage tank 12, hydrogen peroxide solution storage tank 13, and hydrogen peroxide solution storage tank 14, as well as the boron-type ion purification resin column 10 and the lithium-type purification resin column 11; and the concentrations of dissolved oxygen and dissolved hydrogen in the test solution are adjusted by using hydrogen cylinder 1, nitrogen cylinder 2 or oxygen cylinder 3, dissolved oxygen online monitor 7, dissolved hydrogen online monitor 8, and pH online monitor 9, thereby simulating reactor shutdown and variable power conditions. S7. During the test, keep the gamma-ray spectrometers D1-D4 in the on state to measure the deposition characteristics of surface corrosion products and the surface deposition distribution coefficient of each component under varying operating conditions or shutdown conditions, such as fuel element simulator 20, steam generator simulator 24, main pipeline hot pipe section simulator 22 and main pipeline cold pipe section simulator 25.

[0048] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An on-line monitoring device for corrosion product source term deposition characteristics based on neutron source activation, characterized in that, The water storage tank (5), the corrosion sample activation test section (18), the simulated core test section (20), the main pipe hot pipe section simulated body (22), the steam generator simulated body (24), and the main pipe cold pipe section simulated body (25) are sequentially connected to form a loop. The water storage tank (5) is used for storing the test solution and feeding the test solution into the corrosion sample activation test section (18). The corrosion sample activation test section (18) is internally provided with a neutron source (17), and the neutron source (17) is used for irradiation activation of corrosion products in the test solution flowing through the corrosion sample activation test section (18). The simulated core test section (20), the main pipe hot pipe section simulated body (22), the steam generator simulated body (24), and the main pipe cold pipe section simulated body (25) are respectively used for simulating deposition of corrosion products in a pressurized water reactor primary loop on surfaces of fuel elements, a steam generator, and a main pipe. The simulated core test section (20), the main pipe hot pipe section simulated body (22), the steam generator simulated body (24), and the main pipe cold pipe section simulated body (25) are respectively provided with a gamma-ray spectrometer D1, a gamma-ray spectrometer D2, a gamma-ray spectrometer D3, and a gamma-ray spectrometer D4 for monitoring radioactive characteristics of activated corrosion products deposited on surfaces.

2. The on-line monitoring device of corrosion product source term deposition properties based on neutron source activation according to claim 1, characterized in that, The corrosion sample activation test section (18) has a column ring structure, and the internal cavity of the column ring structure is provided with the neutron source (17).

3. The on-line monitoring device of corrosion product source term deposition properties based on neutron source activation according to claim 1, characterized in that, The corrosion sample activation test section (18) is externally provided with a radiation shielding body (19).

4. The on-line monitoring device of corrosion product source term deposition properties based on neutron source activation according to claim 1, characterized in that, The simulated core test section (20) is internally loaded with a fuel element simulated body (21), and the fuel element simulated body (21) is internally provided with an electric heating element for simulating heat generation of the fuel element and realizing simulation of nucleate boiling on a surface of the fuel element.

5. The on-line monitoring device of corrosion product source term deposition properties based on neutron source activation according to claim 1, characterized in that, The main pipe hot pipe section simulated body (22) and the main pipe cold pipe section simulated body (23) are both made of a pressurized water reactor primary loop main pipe material, and are both externally provided with a pipe heat tracing device.

6. The on-line monitoring device of corrosion product source term deposition properties based on neutron source activation according to claim 1, characterized in that, The steam generator simulated body (24) is internally provided with a heat transfer pipe, the test solution flows through the heat transfer pipe, and cooling oil flows outside the heat transfer pipe, and the cooling oil is connected with a secondary side cooling system including an oil cooling cooler (27), a cooling oil circulating pump (28), a cooling oil tank (29), and a water cooling cooler (20).

7. The on-line monitoring device of corrosion product source term deposition properties based on neutron source activation according to claim 1, characterized in that, The steam generator simulated body (24) is connected in parallel with a pressurizer (23), one outlet of the steam generator simulated body (24) is connected with an inlet of the main pipe cold pipe section simulated body (25), the other outlet of the steam generator simulated body (24) is connected with an inlet of the pressurizer (23) through a spray valve V101, an outlet of the pressurizer (23) is combined with an outlet of the main pipe hot pipe section simulated body (22) into one pipe, and the one pipe is connected with an inlet of the steam generator simulated body (24).

8. The on-line monitoring device of corrosion product source term deposition properties based on neutron source activation according to claim 1, characterized in that, One outlet of the main pipe cold pipe section simulated body (25) is connected with an inlet of the corrosion product activation test section (18), and the other outlet of the main pipe cold pipe section simulated body (25) is connected with a sampling cooler (26); an outlet of the sampling cooler (26) is connected with the water storage tank (5) through a pipe, and the pipe between the sampling cooler (26) and the water storage tank (5) is provided with a sampling branch, and the sampling branch is controlled by a hand-operated stop valve V11.

9. The on-line monitoring device of corrosion product source term deposition properties based on neutron source activation according to claim 1, characterized in that, The water storage tank (5) is provided with a liquid inlet, a liquid return port and an exhaust port at the top, and a liquid outlet, a water outlet and an air inlet at the bottom. The air inlet of the water storage tank (5) is connected with a gas cylinder through a pipeline, which is used to adjust the dissolved gas concentration of the test solution by introducing gas into the water storage tank (4). The exhaust port of the water storage tank (5) is connected with a bubbling indicator (4), which is used to observe the introduction condition of high-purity gas.

10. The on-line monitoring apparatus for corrosion product source term deposition properties based on neutron source activation according to claim 1, wherein, A feed water pump (6) and a circulating pump (16) are sequentially arranged between the water storage tank (5) and the corrosion product activation test section (18).

11. The corrosion product source term deposition property on-line monitoring apparatus based on neutron source activation according to claim 10, characterized in that, The outlet of the feed water pump (6) is connected with a water chemistry online monitoring instrument and an ion purification resin column arranged in parallel. The water chemistry online monitoring instrument includes a dissolved oxygen online monitoring instrument (7), a dissolved hydrogen online monitoring instrument (8) and a pH online monitoring instrument (9). The ion purification resin column includes a boron-containing purification resin column (10) and a lithium purification resin column (11).

12. The corrosion product source term deposition property on-line monitoring apparatus based on neutron source activation according to claim 11, characterized in that, A manual stop valve V5 is arranged at the inlet of the water chemistry online monitoring instrument. The outlet is connected with a flow meter F1, a water storage tank (5) through a pipeline in sequence. A manual stop valve V6 is arranged at the inlet of the ion purification resin column. The outlet is connected with a flow meter F2, a water storage tank (6) through a pipeline in sequence.

13. The on-line monitoring apparatus for corrosion product source term deposition properties based on neutron source activation according to claim 1, wherein, A dosing tank is also included. The dosing tank injects boric acid and lithium hydroxide solution, hydrogen peroxide solution or corrosion product solution into the test loop through a dosing pump (15), so as to adjust the boron concentration, lithium concentration and hydrogen peroxide concentration of the test solution.

14. The corrosion product source term deposition property on-line monitoring apparatus based on neutron source activation according to claim 13, characterized in that, The dosing tank includes a boron-lithium solution storage tank (12), a hydrogen peroxide solution storage tank (13) and a corrosion product solution storage tank (14). Manual stop valves V7, V8 and V9 are respectively arranged between the boron-lithium solution storage tank (12), the hydrogen peroxide solution storage tank (13) and the corrosion product solution storage tank (14) and the dosing pump (15).

15. A monitoring method using the on-line monitoring device for deposit characteristics of a corrosion product source term based on neutron source activation according to any one of claims 1 to 14, characterized in that, The method comprises the following steps: S1, installing a fuel element simulation body in a simulation core simulation test section; S2, injecting deionized water into the water storage tank, starting the feed water pump, and injecting boric acid, lithium hydroxide and corrosion product solution into the loop through the dosing pump, so as to adjust the chemical parameters of the test solution to the target value; S3, opening the electric heating switch of the pressure stabilizer, adjusting the pressure of the test loop to the target value, starting the heating power supply of the fuel element simulation body, opening the cooling oil circulating pump, and adjusting the temperature of the test loop coolant to the target value range; S4, opening the gamma spectrometer D1-D4 to continuously measure the fuel element simulation body, the steam generator simulation body, the main pipeline hot pipe section simulation body and the main pipeline cold pipe section simulation body, and obtaining the radioactivity and corresponding intensity of the activated corrosion product deposition layer deposited on the surface of each component online. The element type and activity of the corrosion product deposition are analyzed.

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