Corrosion product solubility test apparatus and method simulating pressurized water reactor primary loop environment

Abstract

This invention discloses a device and method for testing the solubility of corrosion products in a simulated pressurized water reactor primary loop environment. The device comprises a water storage tank, a high-pressure pump, a deoxygenation trap, a test section, a cooler, a metal ion trap, and a drain tank connected in sequence. The water storage tank stores the test solution; the deoxygenation trap contains a platinum mesh catalyst for catalyzing the reaction of dissolved oxygen and dissolved hydrogen; the test section contains a platinum filter for loading the target corrosion products; the cooler cools the test solution; the metal ion trap contains two series-connected purification resins; and the drain tank receives the solution after the test. Through the design of low-metal-release materials and high-temperature components, upstream catalytic deoxygenation in the test section, an open-loop direct-flow structure for the test device, acid injection at the test section outlet, gas purging of the metal ion trap, and series-connected resin collection, the device's background interference and the redeposition of dissolved metal ions during the cooling process are reduced, thereby improving the reliability of the corrosion product solubility test in a simulated pressurized water reactor primary loop environment.

Description

Technical Field

[0001] This invention relates to the field of pressurized water reactor water chemistry technology, specifically to a device and method for testing the solubility of corrosion products in a simulated pressurized water reactor primary loop environment. Background Technology

[0003] In pressurized water reactor (PWR) nuclear power plants, the primary loop structural materials generate corrosion products in the high-temperature, high-pressure water environment. These corrosion products, carried by the coolant into the reactor core, are activated by neutrons to form radioactive nuclides, which then migrate and deposit within the system, ultimately forming the main radiation source term during shutdown maintenance. Statistics show that in French PWR nuclear power plants, activated corrosion products contribute as much as 85% to the collective dose outside the reactor core. Therefore, during the nuclear power plant design phase, it is essential to quantitatively simulate the generation, transport, activation, and deposition behavior of activated corrosion products using source term analysis software to support radiation shielding design, waste management, and personnel dose assessment. Internationally, the development of source term analysis software began as early as the 1970s, with software such as PACTOLE (France) and CORA (USA) established, along with comprehensive verification systems. Although my country has independently developed source term analysis software such as STAP and CAMPSIS, the lack of basic data continues to pose challenges to software verification.

[0004] Among the many parameters affecting source term analysis, the solubility of corrosion products in the coolant is one of the most critical. Solubility directly determines whether corrosion products tend to be released into the coolant or deposited on the structural surface. Therefore, accurately grasping the solubility data of corrosion products under different conditions such as temperature, pH, dissolved hydrogen, and dissolved oxygen is not only a prerequisite for accurate simulation by source term analysis software, but also the theoretical basis for achieving water chemistry optimization and controlling radiation source terms from the source. Currently, experimental data on the solubility of corrosion products under high temperature and high pressure are still relatively scarce. Existing testing devices and methods have the following problems: First, the service environment of the pressurized water reactor primary circuit places stringent requirements on the materials of the testing devices. Traditional stainless steel or nickel-based alloy testing devices will release corrosion products into the system during long-term testing, seriously interfering with the accuracy of solubility test results; Second, the metal ions dissolved from corrosion products are prone to redeposition in the low-temperature region (<250℃) of the testing device, making it difficult to capture all the metal ions dissolved from corrosion products, resulting in lower-than-expected solubility data. Summary of the Invention

[0005] This invention aims to address the challenges in reproducing the reducing aqueous chemical environment, the interference of background metal levels caused by material release during the solubility testing of corrosion products in the primary loop of a pressurized water reactor (PWR), and the redeposition of dissolved metal ions during cooling. It provides a device and method for testing the solubility of corrosion products in a simulated PWR primary loop environment. The device employs a high-temperature container and flow piping with low metal ion release. An oxygen trap containing a platinum mesh catalyst is installed upstream of the test section, and an open-loop flow path is used. The method involves injecting acid at the outlet of the test section and implementing hydrogen purging and protection during the metal ion collection stage. This ensures the stability of dissolved metal ions during cooling, transport, and collection, thereby improving the accuracy and reliability of the solubility test data.

[0006] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a corrosion product solubility testing device simulating the primary loop environment of a pressurized water reactor, comprising a water storage tank, a high-pressure pump, a deoxygenation trap, a test section, a cooler, a metal ion trap, and a drainage tank connected in sequence; the water storage tank is used to store the test solution, and the high-pressure pump is used to pump the test solution; the deoxygenation trap and the test section are arranged in a heating furnace, the deoxygenation trap is provided with a platinum mesh catalyst for catalyzing the reaction of dissolved oxygen and dissolved hydrogen in the test solution, the test section is provided with a platinum filter for loading the target corrosion products, and the cooler is used to cool the test solution flowing out of the test section; the metal ion trap is provided with two purification resins connected in series for capturing dissolved metal ions from the target corrosion products, and the drainage tank is used to receive the test solution flowing out of the metal ion trap.

[0007] As a further embodiment of the present invention, the deoxygenation trap and the test section are both made of titanium alloy lined with platinum-iridium alloy, and the connecting pipes between the high-pressure pump and the deoxygenation trap, the connecting pipes between the deoxygenation trap and the test section, and the connecting pipes between the test section and the cooler are all titanium alloy pipes with gold-plated inner walls.

[0008] As a further aspect of the present invention, it also includes an acid storage tank for storing acid, wherein a circulation pump, a filter, a purification resin and an acid metering pump are sequentially connected between the acid storage tank and the inlet end of the cooler to inject acid into the test solution between the outlet of the test section and the inlet of the cooler.

[0009] As a further embodiment of the present invention, the acid storage tank is made of stainless steel with a polytetrafluoroethylene lining, the connecting pipe between the acid storage tank and the acid injection metering pump is made of steel with a polytetrafluoroethylene lining, and the connecting pipe between the acid injection metering pump and the inlet end of the cooler is a titanium alloy pipe with gold-plated inner wall.

[0010] As a further embodiment of the present invention, the top of the acid storage tank is connected to a safety valve, a pressure gauge and a level gauge, and is also connected in sequence to a pressure reducing valve and an anti-backflow exhaust device; the bottom of the acid storage tank is connected to a hydrogen cylinder and a nitrogen cylinder, and a regulating valve and a one-way valve are provided between the acid storage tank and the hydrogen cylinder, and between the acid storage tank and the nitrogen cylinder.

[0011] As a further embodiment of the present invention, a back pressure valve and a pH meter are sequentially connected between the outlet end of the cooler and the metal ion trap. The cooler, the back pressure valve and their connecting pipes are made of platinum or gold-plated titanium, and the metal ion trap, the drain tank and their connecting pipes are made of polytetrafluoroethylene.

[0012] As a further embodiment of the present invention, the metal ion trap is provided with an inlet and an outlet pipe for the flow of hydrogen gas. A one-way valve, a regulating valve and a hydrogen cylinder are connected in sequence to the inlet pipe, and an anti-backflow exhaust device is connected to the outlet pipe.

[0013] As a further embodiment of the present invention, the outlet pipe of the water storage tank is connected to a circulation pump. One outlet of the circulation pump is connected to two parallel branches. The outlets of the two parallel branches are connected to the water storage tank. The other outlet of the circulation pump is connected in sequence to a filter, a high-pressure pump, a Venturi flow meter, and finally to a deaerator. One of the two parallel branches consists of a dissolved oxygen meter, a dissolved hydrogen meter, a pH meter, and a flow meter connected in series. The other branch consists of a regulating valve and a flow meter connected in series.

[0014] As a further embodiment of the present invention, a safety valve, a pressure gauge and a level gauge are connected to the top of the water storage tank, and a pressure reducing valve and an anti-backflow exhaust device are connected in sequence; a hydrogen cylinder and a nitrogen cylinder are connected to the bottom of the water storage tank, and a regulating valve and a one-way valve are provided between the water storage tank and the hydrogen cylinder, and between the water storage tank and the nitrogen cylinder.

[0015] Secondly, the present invention provides a testing method for testing the solubility of corrosion products using the simulated pressurized water reactor primary loop environment testing device described in the first aspect, comprising the following steps: A. Load the target corrosion products into a platinum filter inside the test section; B. Pour the prepared test solution into the water storage tank; C. Purge the water tank with nitrogen gas until the dissolved oxygen in the test solution reaches the preset range; D. Introduce hydrogen into the water storage tank and regulate the hydrogen pressure in the water storage tank through the pressure reducing valve until the dissolved hydrogen in the test solution reaches the preset range. E. Start the high-pressure pump and heating furnace, and adjust the pressure of the test device and the temperature of the test section to the preset range; F. Adjust the stroke of the high-pressure pump until the flow rate of the test solution reaches the preset range; G. The steady-state operation shall last for no less than 72 hours to allow the dissolution process of the target corrosion products to reach equilibrium. H. Introduce hydrogen into the metal ion trap and simultaneously purge the acid storage tank with nitrogen or hydrogen. Start the circulation pump and acid metering pump to inject the acid into the test solution flowing out of the test section and start timing. I. After completing the preset test duration, remove the two series-connected purification resins. After removing the purification resins, cool and depressurize the device according to the test requirements, or load new purification resins to continue the test. J. Measure the metal element content in the purified resin and calculate the solubility of different metal elements based on the amount of metal elements captured in the purified resin, the flow rate of the test solution, and the test duration.

[0016] Compared with the prior art, the present invention has the following advantages: 1. This invention addresses key issues in the solubility testing of corrosion products in the primary loop of pressurized water reactors, such as background interference, difficulty in maintaining reducing water quality, and the precipitation and redeposition of metal ions during cooling. It designs a corrosion product solubility testing device. By employing a titanium alloy lining with a platinum-iridium alloy, and gold-plated titanium alloy or platinum and other low-metal-release materials as the high-temperature container and flow pipes, combined with platinum mesh catalytic deoxygenation and an open-loop flow process, it can simulate the reducing water chemistry environment of the primary loop of a pressurized water reactor under high temperature and high pressure conditions. This reduces background interference caused by the release of iron, chromium, nickel, and other metal ions from the device itself, thus providing more reliable basic solubility data for activated corrosion product source term analysis, water chemistry optimization, and radiation dose control. 2. The test method proposed in this invention involves introducing nitrogen and hydrogen into the water storage tank before the test to adjust the dissolved oxygen and dissolved hydrogen in the test solution. During the metal ion collection stage, nitrogen or hydrogen is introduced into the acid storage tank and the metal ion collector to replace air, reduce oxygen introduction, and maintain the required reducing atmosphere. At the same time, acid is injected into the test solution at the outlet of the test section to keep the dissolved metal ions in a dissolved state during the cooling and transportation process, and quantitative collection is performed using a series of purification resins. This reduces the measurement error caused by the redeposition of dissolved metal ions in the low-temperature zone and the mixing of air, and improves the integrity, repeatability, and accuracy of the solubility test. Attached Figure Description

[0017] 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 considered 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. In the drawings: Figure 1This is a schematic diagram of the corrosion product solubility testing device for simulating the primary loop environment of a pressurized water reactor in this invention.

[0018] The attached diagram shows the markings and corresponding component names: 1. Water storage tank; 2. High-pressure hydrogen cylinder; 3. High-pressure nitrogen cylinder; 4. Anti-backflow exhaust device; 5. Circulation pump; 6. Dissolved oxygen meter; 7. Dissolved hydrogen meter; 8. pH meter; 9. Filter; 10. High-pressure pump; 11. Venturi flow meter; 12. Deoxygenation trap; 13. Test section; 14. Heating furnace; 15. Acid storage tank; 16. High-pressure hydrogen cylinder; 17. High-pressure nitrogen cylinder; 18. Anti-backflow exhaust device; 19. Circulation pump; 20. Filter; 21. Purifying resin; 22. Acid metering pump; 23. Cooler; 24. pH meter; 25. High-pressure hydrogen cylinder; 26. Anti-backflow exhaust device; 27. Purifying resin; 28. Purifying resin; 29. ​​Metal ion trap; 30. Drainage tank; V1. Regulating valve; V2. Regulating valve; V3. Regulating valve; V4. Regulating valve; V5. Regulating valve; V6. Regulating valve; V7. Regulating valve; V8. Regulating valve; RV1 Pressure reducing valve; RV2 pressure reducing valve; BPV1 back pressure valve; SV1 safety valve; SV2 safety valve; F1 flow meter; F2 flow meter; P is a check valve; P is a pressure gauge; L is a level gauge. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0021] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly indicating the number, specific order, or primary and secondary relationship of the indicated technical features.

[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0023] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0024] In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width, and other dimensions of various components in the embodiments of this application shown in the accompanying drawings, as well as the overall thickness, length, width, and other dimensions of the integrated device, are merely illustrative and should not constitute any limitation on this application.

[0025] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces), unless otherwise explicitly specified.

[0026] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0027] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0028] During the design phase of nuclear power plants, source term analysis software is essential for quantitatively simulating the generation, transport, activation, and deposition of activated corrosion products. This simulation supports radiation shielding design, waste management, and personnel dose assessment. Among the many parameters influencing source term analysis, the solubility of corrosion products in the coolant is one of the most critical. Solubility directly determines whether corrosion products tend to be released into the coolant or deposited on structural surfaces. Therefore, accurately determining the solubility data of corrosion products under different conditions such as temperature, pH, dissolved hydrogen, and dissolved oxygen is not only a prerequisite for accurate simulation using source term analysis software but also the theoretical foundation for optimizing water chemistry and controlling radiation source terms at their source.

[0029] Currently, experimental data on the solubility of corrosion products under high temperature and high pressure are still relatively scarce. Existing testing devices and methods have the following problems: First, the service environment of the pressurized water reactor primary circuit places stringent requirements on the materials of the testing devices. Traditional stainless steel or nickel-based alloy testing devices will release corrosion products into the system during long-term testing, which seriously interferes with the accuracy of solubility test results. Second, the metal ions dissolved from the corrosion products are prone to redeposition in the low-temperature zone (<250℃) of the testing device, making it difficult to capture all the metal ions dissolved from the corrosion products, resulting in lower solubility data obtained from the test.

[0030] In light of this, the applicant, after in-depth research, proposed a device and method for testing the solubility of corrosion products based on low-background material control, catalytic deoxygenation, open-loop direct flow, acid injection at the test section outlet, and tandem resin trapping. These technical measures work together to stably construct a high-temperature, high-pressure reducing aqueous chemical environment simulating the primary loop of a pressurized water reactor, reducing the impact of metal particle release from the device itself and the precipitation and redeposition of dissolved ions during the cooling process on the test results.

[0031] Please refer to Figure 1 This application provides a device for testing the solubility of corrosion products in a simulated pressurized water reactor primary loop environment. The device comprises a water storage tank 1, a high-pressure pump 10, a deoxygenation trap 12, a test section 13, a cooler 23, a metal ion trap 29, and a drainage tank 30 connected in sequence. The water storage tank 1 stores the test solution, and the high-pressure pump 10 pumps the test solution. The deoxygenation trap 12 and the test section 13 are housed within a heating furnace 14. The deoxygenation trap 12 contains a platinum mesh catalyst for catalyzing the reaction of dissolved oxygen and dissolved hydrogen in the test solution. The test section 13 contains a platinum filter for loading the target corrosion products. The cooler 23 cools the test solution flowing out of the test section 13. The metal ion trap 29 contains two series-connected purification resins 27 and 28 for capturing metal ions dissolved from the target corrosion products. The drainage tank 30 receives the test solution flowing out of the metal ion trap 29.

[0032] The test solution in the water storage tank 1 of this application is pressurized by the high-pressure pump 10 and sent into the subsequent deoxygenation trap 12, test section 13, cooler 23, metal ion collector 29, and drain tank 30. The entire testing device is an open-loop system, with the test solution passing through the high-temperature test section 13 in one go. After testing, the test solution is collected and stored in the drain tank 30 and is not recycled. The deoxygenation trap 12 and test section 13 are set in the heating furnace 14. The heating furnace 14 provides the required temperature for the test, and the high-pressure pump 10 and back pressure valve BPV1 work together to provide the required pressure and flow rate, so that the pressure, temperature, and flow rate of the testing device reach the preset range.

[0033] The aforementioned deoxygen trap 12 is a high-temperature flow-through deoxygenation device internally equipped with a platinum mesh catalyst. The platinum mesh catalyst promotes the reaction between dissolved oxygen and dissolved hydrogen in the test solution, thereby removing residual trace dissolved oxygen and maintaining the reducing water chemistry environment of the pressurized water reactor primary loop. The aforementioned test section 13 is internally equipped with a platinum filter screen for loading target corrosion products (such as iron(III) oxide). When the test solution passes through test section 13, the target corrosion products dissolve metal ions. These metal ions travel with the test solution to the metal ion collector 29, where they are captured by two purification resins connected in series. The purification resin in this application is a nuclear-grade ion exchange resin.

[0034] According to some embodiments of this application, both the deoxygenation trap 12 and the test section 13 are made of titanium alloy lined with platinum-iridium alloy. The connecting pipes between the high-pressure pump 10 and the deoxygenation trap 12, between the deoxygenation trap 12 and the test section 13, and between the test section 13 and the cooler 23 are all titanium alloy pipes with gold-plated inner walls, and the sealing gaskets of each connecting pipe are made of titanium alloy. By adopting the above scheme and optimizing the materials of the above high-temperature components, the background interference caused by the release of metal ions such as iron, chromium, and nickel from the test device itself can be effectively reduced, so that the measured metal elements mainly originate from the target corrosion products, thereby improving the accuracy of the test results.

[0035] According to some embodiments of this application, an acid storage tank 15 is also included for storing acid. A circulation pump 19, a filter 20, a purification resin 21, and an acid metering pump 22 are sequentially connected between the acid storage tank 15 and the inlet of the cooler 23 to inject acid into the test solution between the outlet of the test section 13 and the inlet of the cooler 23. A regulating valve V7 is also provided between the circulation pump 19 and the acid storage tank 15. The acid stored in the acid storage tank 15 can be hydrochloric acid. The concentration and injection flow rate of the hydrochloric acid are determined based on the hydrolysis and precipitation characteristics of the metal ions to be tested and the preset acidity range of the test solution after acid injection, so that the dissolved metal ions remain in a dissolved state during cooling and transportation.

[0036] Since the test solution flowing out of test section 13 is at a high temperature, its temperature decreases after entering cooler 23. Some dissolved metal ions may redeposit in the low-temperature zone due to changes in dissolution equilibrium, hydrolysis, or precipitation. In this application, acid is injected into the test solution before the inlet of cooler 23 by acid metering pump 22, adjusting the acid-injected test solution to a preset acidity range. This ensures that the dissolved metal ions remain dissolved during cooling and transport, and are captured by the purification resin in metal ion collector 29, thereby reducing measurement deviations caused by metal ion precipitation and redeposition.

[0037] According to some embodiments of this application, the acid storage tank 15 is made of stainless steel lined with polytetrafluoroethylene (PTFE), the connecting pipe between the acid storage tank 15 and the acid metering pump 22 is made of steel lined with PTFE, and the connecting pipe between the acid metering pump 22 and the inlet end of the cooler 23 is a titanium alloy pipe with gold-plated inner walls. By adopting the above scheme and optimizing the materials of the acid injection container and pipeline, the risk of introducing additional metal ions during the injection of hydrochloric acid solution can be reduced, thereby improving the accuracy of solubility test results.

[0038] According to some embodiments of this application, the top of the acid storage tank 15 is connected to a safety valve SV2, a pressure gauge and a level gauge, and is also connected in sequence to a pressure reducing valve RV2 and an anti-backflow exhaust device 18; the bottom of the acid storage tank 15 is connected to a high-pressure hydrogen cylinder 16 and a high-pressure nitrogen cylinder 17, a regulating valve V5 and a check valve are provided between the acid storage tank 15 and the high-pressure hydrogen cylinder 16, and a regulating valve V6 and a check valve are provided between the acid storage tank 15 and the high-pressure nitrogen cylinder 17.

[0039] By installing a pressure gauge and safety valve SV2 on the top of the acid storage tank 15, automatic pressure relief protection can be implemented when the pressure in the acid storage tank 15 exceeds the set value. Introducing hydrogen or nitrogen into the hydrochloric acid through a high-pressure hydrogen cylinder 16 or a high-pressure nitrogen cylinder 17 can reduce the dissolved oxygen in the hydrochloric acid solution and displace the air in the gas phase space of the acid storage tank 15, preventing the introduction of oxygen into the test solution during the acid injection process; the introduction of hydrogen also helps maintain a reducing atmosphere. The anti-backflow exhaust device in this application is mainly used to prevent outside air from being drawn into the container during exhaust. Appropriate products can be selected according to actual conditions; its specific structure and principle will not be elaborated here.

[0040] According to some embodiments of this application, a back pressure valve BPV1 and a pH meter 24 are sequentially connected between the outlet end of the cooler 23 and the metal ion trap 29. The back pressure valve BPV1 works in conjunction with the high-pressure pump 10 to regulate the pressure in the test pipeline, preventing the pressure in the test pipeline from exceeding the limit. The pH meter 24 measures the pH value of the test solution after the acid solution is injected to confirm that the test solution has reached the preset acidity range. The cooler 23, the back pressure valve BPV1, and their connecting pipes are made of platinum or gold-plated titanium, while the metal ion trap 29, the drain tank 30, and their connecting pipes are made of polytetrafluoroethylene, thereby reducing the risk of the device materials introducing additional metal ions into the test solution.

[0041] According to some embodiments of this application, the metal ion trap 29 is provided with an inlet pipe and an outlet pipe for hydrogen gas flow. The inlet pipe is connected in sequence to a one-way valve, a regulating valve V8, and a high-pressure hydrogen cylinder 25, and the outlet pipe is connected to an anti-backflow exhaust device 26. Before and during the test, hydrogen gas is introduced into the metal ion trap 29 to replace the air inside the trap and create a gaseous protection, reducing changes in the valence state of metal ions, precipitation, or resin trapping behavior caused by the entry of oxygen.

[0042] According to some embodiments of this application, the bottom outlet pipe of the water storage tank 1 is connected to a circulation pump 5. One outlet of the circulation pump 5 is connected to two parallel branches, and the outlets of the two parallel branches are connected to the water storage tank 1. The other outlet of the circulation pump 5 is connected in sequence to a filter 9, a high-pressure pump 10, and a Venturi flow meter 11, and finally connected to a deoxygenation trap 12 placed in the heating furnace 14. One of the two parallel branches consists of a dissolved oxygen meter 6, a dissolved hydrogen meter 7, a pH meter 8, and a flow meter F1 connected in series, and the other branch consists of a regulating valve V4 and a flow meter F2 connected in series.

[0043] The aforementioned circulating pump 5 allows the test solution to circulate back to the storage tank 1 via two parallel branches. The dissolved oxygen meter 6, dissolved hydrogen meter 7, pH meter 8, and flow meter F1 can monitor the dissolved oxygen concentration, dissolved hydrogen concentration, pH value, flow rate, and other parameters of the test solution, thereby ensuring that the parameters of the test solution meet the requirements.

[0044] According to some embodiments of this application, the top of the water storage tank 1 is connected to a safety valve SV1, a pressure gauge and a level gauge, and is also connected in sequence to a pressure reducing valve RV1 and an anti-backflow exhaust device 4; the bottom of the water storage tank 1 is connected to a high-pressure hydrogen cylinder 2 and a high-pressure nitrogen cylinder 3, a regulating valve V1 and a check valve are provided between the water storage tank 1 and the high-pressure hydrogen cylinder 2, and a regulating valve V2 and a check valve are provided between the water storage tank 1 and the high-pressure nitrogen cylinder 3.

[0045] By installing a pressure gauge and safety valve SV1 on the top of the water storage tank 1, automatic pressure relief protection can be implemented when the pressure in the water storage tank 1 exceeds the set value. High-purity nitrogen and high-purity hydrogen are introduced into the water storage tank 1 through high-pressure hydrogen cylinder 2 and high-pressure nitrogen cylinder 3. Combined with the online measurement of dissolved oxygen gauge 6 and dissolved hydrogen gauge 7, the concentration of dissolved hydrogen and dissolved oxygen in the test solution can be controlled online.

[0046] It should be noted that the water storage tank 1, filter 9, flow-through components of the high-pressure pump 10, venturi flow meter 11, and connecting pipes in this application can all be made of titanium or platinum with gold-plated inner walls.

[0047] It should be noted that the testing device in this application may also be equipped with over-temperature alarm function, low temperature alarm function, over-pressure alarm function, low pressure alarm function, high liquid level alarm function, low liquid level alarm function, and abnormal flow alarm function. Through data acquisition and control system, the device can monitor and control water chemical parameters such as temperature, pressure, flow rate, dissolved hydrogen, dissolved oxygen concentration, and pH value in real time to ensure the safety of the test device operation.

[0048] The present application provides a testing method for the corrosion product solubility testing device using the simulated pressurized water reactor primary loop environment described above, comprising the following steps: A. Load the target corrosion products into a platinum filter inside test section 13; B. Pour the prepared test solution into water storage tank 1; C. Purge the water storage tank 1 with high-purity nitrogen gas until the dissolved oxygen in the test solution reaches the preset range. Specifically: open the regulating valve V2, fully open the pressure reducing valve RV1 to allow high-purity nitrogen gas to circulate in the water storage tank 1 and begin the deoxygenation operation. At the same time, open the regulating valve V3, start the circulation pump 5, and adjust the opening of the regulating valve V4. Monitor the dissolved oxygen in the test solution using the dissolved oxygen meter 6. Once the dissolved oxygen reaches the preset range, close the regulating valve V2. D. Introduce high-purity hydrogen into water storage tank 1 and regulate the hydrogen pressure in water storage tank 1 through pressure reducing valve RV1 until the dissolved hydrogen reaches the preset range. Specifically, open regulating valve V1 and slowly close the opening of pressure reducing valve RV1 to allow high-purity hydrogen to enter water storage tank 1, while monitoring the pressure gauge and dissolved hydrogen gauge 7 of water storage tank 1. When the dissolved hydrogen reaches the preset range, close regulating valve V1. E. Start the high-pressure pump 10 and the heating furnace 14 to adjust the pressure of the test device and the temperature of the test section 13 to the preset range. Specifically, start the high-pressure pump 10 and adjust the back pressure valve BPV1 to make the pressure of the test pipeline reach the preset range; start the heating furnace 14 to make the temperature of the test section 13 reach the preset range. F. Adjust the stroke of the high-pressure pump 10 and monitor the flow rate of the test solution through the Venturi flow meter 11 until the flow rate of the test solution reaches the preset range; G. The steady-state operation shall last for no less than 72 hours to allow the dissolution process of the target corrosion products to reach equilibrium. H. Open the regulating valve V8 to introduce high-purity hydrogen into the metal ion trap 29. At the same time, open the regulating valve V6 or the regulating valve V5 to introduce high-purity nitrogen or hydrogen into the acid storage tank 15. Start the circulation pump 19 and the acid metering pump 22 to inject acid into the test solution between the outlet of the test section 13 and the inlet of the cooler 23, and start timing. I. After completing the preset test duration, close the regulating valve V8, remove the two series-connected purification resins 27 and 28, and after removing the purification resins, cool and depressurize the device according to the test requirements, or load new purification resins to continue the test. J. According to "NB / T 25097 Determination of Metal Impurity Content in Ion Exchange Resins for Nuclear Power Plants", the metal element content in the purified resin was measured, and the solubility of different metal elements was obtained according to the following formula: ; In the formula, S M The solubility of metallic element M in the target corrosion product is expressed in μmol / kg. C M The content of metal element M in the purified resin obtained by testing is expressed in μg. F represents the flow rate of the testing device, in kg / h. t represents the test duration, in hours (h). m is the molar mass of the metallic element M, expressed in g / mol.

[0049] It should be noted that the "preset range" mentioned in this application is a parameter range predetermined based on the specific operating conditions of the primary loop of the pressurized water reactor to be simulated, the types of corrosion products to be tested, and the purpose of the test. This range includes dissolved oxygen, dissolved hydrogen, pressure, temperature, flow rate, and test duration. The water chemical and thermal-hydraulic parameters may differ for different reactor types, operating stages, and research objects; therefore, the above parameters are not limited to a single fixed value.

[0050] 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. A device for testing the solubility of corrosion products in a simulated pressurized water reactor primary loop environment, characterized in that, The system comprises, in sequence, a water storage tank, a high-pressure pump, a deoxygenation trap, a test section, a cooler, a metal ion collector, and a drainage tank. The water storage tank stores the test solution, and the high-pressure pump pumps the test solution. The deoxygenation trap and the test section are located within a heating furnace. The deoxygenation trap contains a platinum mesh catalyst for catalyzing the reaction between dissolved oxygen and dissolved hydrogen in the test solution. The test section contains a platinum filter for loading the target corrosion products. The cooler cools the test solution flowing out of the test section. The metal ion collector contains two series-connected purification resins for capturing metal ions dissolved from the target corrosion products. The drainage tank receives the test solution flowing out of the metal ion collector.

2. The apparatus for testing the solubility of corrosion products in a simulated pressurized water reactor primary loop environment according to claim 1, characterized in that, Both the deoxygenator and the test section are made of titanium alloy lined with platinum-iridium alloy. The connecting pipes between the high-pressure pump and the deoxygenator, between the deoxygenator and the test section, and between the test section and the cooler are all titanium alloy pipes with gold-plated inner walls.

3. The apparatus for testing the solubility of corrosion products in a simulated pressurized water reactor primary loop environment according to claim 1, characterized in that, It also includes an acid storage tank for storing acid, and a circulation pump, a filter, a purification resin and an acid metering pump are connected in sequence between the acid storage tank and the inlet of the cooler to inject acid into the test solution between the outlet of the test section and the inlet of the cooler.

4. The apparatus for testing the solubility of corrosion products in a simulated pressurized water reactor primary loop environment according to claim 3, characterized in that, The acid storage tank is made of stainless steel with a polytetrafluoroethylene (PTFE) lining. The connecting pipe between the acid storage tank and the acid injection metering pump is made of steel with a PTFE lining. The connecting pipe between the acid injection metering pump and the inlet of the cooler is made of titanium alloy with a gold-plated inner wall.

5. The apparatus for testing the solubility of corrosion products in a simulated pressurized water reactor primary loop environment according to claim 3, characterized in that, The top of the acid storage tank is connected to a safety valve, a pressure gauge, and a level gauge, and is also connected in sequence to a pressure reducing valve and an anti-backflow venting device; the bottom of the acid storage tank is connected to a hydrogen cylinder and a nitrogen cylinder, and a regulating valve and a one-way valve are installed between the acid storage tank and the hydrogen cylinder, and between the acid storage tank and the nitrogen cylinder.

6. The apparatus for testing the solubility of corrosion products in a simulated pressurized water reactor primary loop environment according to claim 1, characterized in that, A back pressure valve and a pH meter are connected sequentially between the outlet end of the cooler and the metal ion trap. The cooler, the back pressure valve and their connecting pipes are made of platinum or gold-plated titanium. The metal ion trap, the drain tank and their connecting pipes are made of polytetrafluoroethylene.

7. The apparatus for testing the solubility of corrosion products in a simulated pressurized water reactor primary loop environment according to claim 1, characterized in that, The metal ion trap is equipped with inlet and outlet pipes for hydrogen flow. A one-way valve, a regulating valve and a hydrogen cylinder are connected in sequence to the inlet pipe, and an anti-backflow exhaust device is connected to the outlet pipe.

8. The apparatus for testing the solubility of corrosion products in a simulated pressurized water reactor primary loop environment according to claim 1, characterized in that, The water outlet pipe of the water storage tank is connected to a circulation pump. One outlet of the circulation pump is connected to two parallel branches. The outlets of the two parallel branches are connected to the water storage tank. The other outlet of the circulation pump is connected in sequence to a filter, a high-pressure pump, a Venturi flow meter, and finally to a deaerator. One of the two parallel branches consists of a dissolved oxygen meter, a dissolved hydrogen meter, a pH meter, and a flow meter connected in series. The other branch consists of a regulating valve and a flow meter connected in series.

9. The apparatus for testing the solubility of corrosion products in a simulated pressurized water reactor primary loop environment according to claim 8, characterized in that, The top of the water storage tank is connected to a safety valve, a pressure gauge, and a level gauge, and is also connected in sequence to a pressure reducing valve and an anti-backflow venting device; the bottom of the water storage tank is connected to a hydrogen cylinder and a nitrogen cylinder, and a regulating valve and a one-way valve are installed between the water storage tank and the hydrogen cylinder, and between the water storage tank and the nitrogen cylinder.

10. A test method using the corrosion product solubility testing apparatus for simulating the primary loop environment of a pressurized water reactor as described in any one of claims 1-9, characterized in that, Includes the following steps: A. Load the target corrosion products into a platinum filter inside the test section; B. Pour the prepared test solution into the water storage tank; C. Purge the water tank with nitrogen gas until the dissolved oxygen in the test solution reaches the preset range; D. Introduce hydrogen into the water storage tank and regulate the hydrogen pressure in the water storage tank through the pressure reducing valve until the dissolved hydrogen in the test solution reaches the preset range. E. Start the high-pressure pump and heating furnace, and adjust the pressure of the test device and the temperature of the test section to the preset range; F. Adjust the stroke of the high-pressure pump until the flow rate of the test solution reaches the preset range; G. The steady-state operation shall last for no less than 72 hours to allow the dissolution process of the target corrosion products to reach equilibrium. H. Introduce hydrogen into the metal ion trap and simultaneously purge the acid storage tank with nitrogen or hydrogen. Start the circulation pump and acid metering pump to inject the acid into the test solution flowing out of the test section and start timing. I. After the preset test time is completed, remove the two series-connected purification resins. After removing the purification resins, cool and depressurize the device according to the test requirements, or load new purification resins to continue the test. J. Measure the metal element content in the purified resin and calculate the solubility of different metal elements based on the amount of metal elements captured in the purified resin, the flow rate of the test solution, and the test duration.

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