A simulation experiment device for full stress corrosion of high-temperature nitric acid in spent fuel reprocessing

Abstract

The application provides a spent fuel reprocessing high-temperature nitric acid full stress corrosion simulation experiment device, and relates to the technical field of spent fuel reprocessing. The device comprises an electric control system and a load loading system, a corrosion reaction system, an electrochemical test system, a temperature control system and a tail gas treatment system connected with the electric control system. The load loading system is used for loading various loads. The corrosion reaction system is composed of a glass reaction tank and a reaction tank cover. The reaction tank contains nitric acid solution for corrosion reaction of the sample. The sample penetrates the glass reaction tank and is sealed by a sealing kit. The electrochemical test system is arranged in the reaction tank cover and used for electrochemical test of the sample corrosion reaction. The temperature control system is used for adjusting and controlling the temperature of the sample corrosion reaction of the load loading system. The tail gas treatment system realizes treatment of the tail gas generated in the sample corrosion process. The device solves the problem that the stress corrosion test under high-temperature nitric acid cannot be carried out at present.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of spent fuel reprocessing, and particularly relates to a simulation experiment device for high-temperature nitric acid full stress corrosion in spent fuel reprocessing. BACKGROUND

[0002] Spent fuel reprocessing is a key link for nuclear fuel recycling. At present, the mainstream process of reprocessing in the world is the PUREX process: the spent fuel dissolved in boiling concentrated nitric acid is extracted, separated and purified to prepare new fuel assemblies. This process setting makes the spent fuel reprocessing equipment serve in the environment of high-concentration and high-radioactivity boiling concentrated nitric acid, which puts forward very high requirements for the corrosion resistance of the materials used in the equipment.

[0003] During the spent fuel reprocessing process, some key equipment of the spent fuel reprocessing is operated under the combined action of high-temperature nitric acid corrosion and equipment load, so there is a problem of high-temperature nitric acid stress corrosion. Therefore, it is necessary to carry out simulation experiments on the stress corrosion behavior of the main materials for manufacturing the spent fuel reprocessing equipment. Although domestic and foreign scholars have carried out a large number of researches on the stress corrosion behavior of materials, no scholars have carried out relevant researches on the stress corrosion behavior of materials under high-temperature nitric acid environment. This is mainly because the sealing design of the reported stress corrosion devices is difficult to meet the high-temperature nitric acid environment with strong oxidation, and the load loading and sealing are mutually restricted. SUMMARY

[0004] The technical problem solved by the present application is to provide a simulation experiment device for high-temperature nitric acid full stress corrosion in spent fuel reprocessing, which is aimed at the deficiencies of the prior art, carries out experimental simulation on the high-temperature nitric acid full stress corrosion in spent fuel reprocessing, solves the problem that the stress corrosion test under high-temperature nitric acid cannot be carried out at present, and realizes the systematic evaluation of the stress corrosion behavior of related materials under the reprocessing working condition.

[0005] To solve the above technical problems, the technical scheme adopted by the present application is: a spent fuel post-processing high-temperature nitric acid full stress corrosion simulation experiment device, comprising a load loading system, a corrosion reaction system, an electrochemical test system, a temperature control system, a tail gas treatment system and an electric control system; the load loading system is used for loading various loads, and is connected with the electric control system, so that the type of load applied to the sample is set and the size of the load is controlled through the electric control system; the corrosion reaction system is composed of a glass reaction tank and a reaction tank cover with a central opening, and the glass reaction tank contains nitric acid solution for corrosion reaction of the sample; the sample for corrosion reaction penetrates through the glass reaction tank and is sealed by a sealing kit; the electrochemical test system is arranged in the reaction tank cover and is connected with the electric control system, and is used for electrochemical test of the sample corrosion reaction; the temperature control system is connected with the electric control system, and is used for adjusting and controlling the temperature of the sample corrosion reaction of the load loading system; the tail gas treatment system is connected with the central opening of the reaction tank cover through a condenser tube, so as to realize the treatment of the tail gas generated in the sample corrosion process; the electric control system is connected with the electrochemical test system, the load loading system and the temperature control system through wires.

[0006] Preferably, the load loading system adopts a horizontal tensile-compressive-torsional integrated testing machine, which is used to apply different types of loads to the sample, and the testing machine is fixed with the sample through six-chuck chucks arranged at both ends and is connected with the electric control system through wires, and the type of load and the size of load loading are controlled and set through the control panel of the tensile-compressive-torsional integrated testing machine or the electric control system.

[0007] Preferably, the glass reaction tank of the corrosion reaction system is placed on the middle platform of the horizontal tensile-compressive-torsional integrated testing machine; two holes with the same size and facing each other are respectively arranged on the two surfaces of the glass reaction tank facing the load loading system, the sample penetrates through the centers of the two holes, and the sample in the glass reaction tank is sealed through the sealing kit.

[0008] Preferably, the sealing kit comprises: a pure titanium clamp, a turned polytetrafluoroethylene universal sleeve, a polytetrafluoroethylene flange plate, an expanded polytetrafluoroethylene sealing ring and a polytetrafluoroethylene fastening nut.

[0009] Preferably, the sample adopts a standard dumbbell-shaped tensile sample, a round bar-shaped sample or a plate-shaped sample fixed by a specially designed clamp.

[0010] Preferably, the temperature control system comprises a heat-resistant glass-made tubular heating pipe, a temperature sensor and a heating control circuit, one end of the heat-resistant glass-made tubular heating pipe is inserted into the tank cover, the other end is arranged in the glass-made reaction tank of the corrosion reaction system, and is 1-1.5 cm away from the bottom of the tank, the temperature sensor and the heating control circuit are both arranged in the tank cover and connected with the glass-made tubular heating pipe and the electric control system through wires respectively, for testing the temperature of the heating pipe and transmitting the tested temperature to the electric control system; the heat-resistant glass-made tubular heating pipe is connected with the electric control system through the heating control circuit, so as to realize the temperature regulation and control in the reaction tank.

[0011] Preferably, the electrochemical test system comprises a three-electrode system and an electrochemical workstation; the three-electrode system comprises a working electrode, a counter electrode and a high-temperature nitric acid reference electrode which pass through the tank cover; the working electrode is connected with the sample and arranged outside the reaction tank; the counter electrode is arranged in the solution in the reaction tank; one end of the high-temperature nitric acid reference electrode is arranged in the solution in the reaction tank, and the other end is arranged outside the reaction tank; the working electrode, the platinum electrode and the high-temperature nitric acid reference electrode are further connected with the electrochemical workstation through wires, and the platinum electrode is 3-4 cm away from the heat-resistant glass-made tubular heating pipe of the temperature control system.

[0012] Preferably, the experimental device further comprises an electromagnetic shielding box, the electrochemical workstation in the electrochemical test system is arranged in the electromagnetic shielding box, the electromagnetic shielding box is provided with a hole on the side, and the electrochemical workstation is connected with the electric control system through wires passing through the electromagnetic shielding box.

[0013] Preferably, the experimental device further comprises a fume hood, the load loading system, the corrosion reaction and electrochemical test system, the temperature control system and the tail gas treatment system are all arranged in the fume hood.

[0014] Preferably, the electric control system comprises a temperature control module and a load loading control module, wherein: the temperature control module is connected with the temperature sensor and the heating control circuit through wires, for recording and controlling the real-time temperature of the solution in the reaction tank and controlling the output power of the heat-resistant glass-made tubular heating pipe; the load loading control module is connected with the control panel of the tensile-compressive-torsional integrated testing machine through wires, for controlling the load type and the load size, and controlling the start and stop of the tensile-compressive-torsional integrated testing machine.

[0015] The beneficial effects of adopting the above technical solution are as follows: The simulation experimental device for high-temperature nitric acid full-stress corrosion of spent fuel reprocessing provided by this invention can simulate the stress corrosion behavior of materials under high-temperature nitric acid environment. It can simultaneously realize stress corrosion loading and in-situ electrochemical testing of materials under high-temperature nitric acid environment, and obtain information such as corrosion potential and corrosion current of materials in real time, realizing rapid material evaluation. It can provide data and technical support for stress corrosion life assessment and online corrosion monitoring of related components. It can simulate the stress corrosion behavior of mechanical parts or metal components under complex working conditions such as variable load and non-constant and non-uniform deformation with high fidelity. It can also use this device as a platform to carry out constant load tests, slow strain rate tests, and fracture mechanics tests. At the same time, the experimental device can ensure that the load can be freely applied to the sample through the use of various sealing components, and the deformation and displacement of the sample will not affect the seal or the container. It ensures that the sample can be freely stretched, compressed, and torn under good sealing conditions, and provides double insurance to prevent leakage of corrosive liquid. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a simulation experimental device for high-temperature nitric acid full-stress corrosion of spent fuel reprocessing, provided in an embodiment of the present invention.

[0017] Figure 2 This is a schematic diagram of the corrosion reaction system and electrochemical testing system in the experimental apparatus provided in the embodiments of the present invention;

[0018] Figure 3 This is a schematic diagram of the structure of the through-wall flange plate combined universal sleeve sealing kit provided in an embodiment of the present invention;

[0019] Figure 4 This is a schematic diagram of a reference electrode provided in an embodiment of the present invention.

[0020] In the diagram: 1. Integrated tensile, compressive, and torsional testing machine; 2. Control panel of the testing machine; 3. Six-jaw chuck I; 4. Sample; 5. Pure titanium clamp I; 6. Machined PTFE universal sleeve I; 7. PTFE fastening nut I; 8. Expanded PTFE sealing ring I; 9. Expanded PTFE sealing ring II; 10. PTFE flange plate I; 11. Machined PTFE universal sleeve II; 12. Pure titanium clamp II; 13. Pure titanium clamp III; 14. Machined PTFE universal sleeve III; 15. PTFE flange plate II; 16. Expanded PTFE sealing ring III; 17. Expanded PTFE sealing ring I V; 18. PTFE fastening nut II; 19. Turned PTFE universal joint IV; 20. Pure titanium clamp IV; 21. Six-jaw chuck II; 22. Platinum electrode; 23. Condenser tube; 24. Heat-resistant glass tubular heating tube; 25. Temperature sensor; 26. Salt bridge; 27. Beaker with a PTFE top cover with two holes; 28. Saturated calomel electrode; 29. ​​Glass reaction tank; 30. Expanded PTFE sealing ring; 31. Reaction tank cover; 32. Electrochemical workstation; 33. Wire I; 34. Wire II; 35. Wire III; 36. Wire IV; 37. Electromagnetic shielding box; 38. Electrical control system. Detailed Implementation

[0021] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0022] In this embodiment, as Figure 1 , 2As shown, it includes a load loading system, a corrosion reaction system, an electrochemical testing system, a temperature control system, an exhaust gas treatment system, an electrical control system 38, and a fume hood; the load loading system, corrosion reaction system, electrochemical testing system, temperature control system, and exhaust gas treatment system are all placed inside the fume hood. The load loading system is used for applying various loads. It is connected to the electrical control system, which sets the type of load applied to the sample and controls the load magnitude. The corrosion reaction system consists of a glass reaction tank 29 and a tank cover 30 with a central opening. Nitric acid solution is placed in the glass reaction tank 29 for the corrosion reaction of sample 4. The sample used for the corrosion reaction passes through the glass reaction tank 29 and is sealed by a sealing kit. Samples can be standard dumbbell-shaped tensile specimens, round rod-shaped specimens, or plate-shaped specimens fixed by special clamps. The electrochemical testing system is located inside the tank cover 30 and connected to the electrical control system for electrochemical testing of the sample corrosion reaction. The temperature control system is connected to the electrical control system to regulate and control the temperature of the sample corrosion reaction during the load loading system. The exhaust gas treatment system uses a condenser pipe 23 connected to the central opening 30 of the tank cover to treat the exhaust gas generated during the corrosion of sample 4. The electrical control system is connected to the electrochemical testing system, the load loading system, and the temperature control system via wires.

[0023] In this embodiment, the load loading system adopts a horizontally placed tension-compression-torsion integrated testing machine 1, which is used to apply different types of loads to the specimen. The testing machine is fixed to the specimen 4 by six-jaw chucks I3 and II21 set on the left and right sides, and is connected to the electrical control system 38 through wire II34. The type of load selection and the magnitude of load loading are controlled and set by the control panel of the tension-compression-torsion integrated testing machine 1 or the electrical control system 38, and can apply tensile, compressive, torsional and other types of loads.

[0024] In this embodiment, the glass reaction tank 29 of the corrosion reaction system is placed on the middle section of the horizontally placed tension-compression-torsion integrated testing machine 1; the glass reaction tank 29 has two holes of the same size and position facing each other on the two sides facing the six-jaw chuck I3 and the six-jaw chuck II21, and the sample 4 passes through the center of the two holes and is sealed in the glass reaction tank 29 by a sealing kit.

[0025] In this embodiment, the temperature control system includes a heat-resistant glass tube heating element 24, a temperature sensor 25, and a heating control circuit. One end of the heat-resistant glass tube heating element 24 is inserted into the reaction tank cover 30, and the other end is placed in the glass reaction tank 29 of the corrosion reaction system, 1-1.5 cm from the bottom of the tank. The temperature sensor 25 and the heating control circuit are both placed inside the reaction tank cover 30 and connected to the glass tube heating element 24 and the electrical control system 38 respectively through wires IV36 and III35. The temperature sensor 25 is used to test the temperature of the heating element 24 and transmit the tested temperature to the electrical control system 38. The heat-resistant glass tube heating element 24 is connected to the electrical control system 38 through the heating control circuit to realize the temperature adjustment and control in the reaction tank 29. The temperature control range is 20-300℃.

[0026] In this embodiment, the electrochemical testing system includes a three-electrode system, an electrochemical workstation 32, and an electromagnetic shielding box 37. The electrochemical workstation 32 is placed inside the electromagnetic shielding box 37, which has an opening on its side. The electrochemical workstation 32 is connected to the electronic control system 38 via a wire passing through the electromagnetic shielding box. The three-electrode system includes a working electrode passing through the reaction tank cover 30, a platinum electrode (i.e., counter electrode) 22, a salt bridge 26 with porous ceramic cores at both ends, a saturated calomel electrode 28, and a beaker 27 containing saturated KCl solution. The working electrode 30 is connected to the sample 4 and placed outside the reaction tank 29. The platinum electrode 22 is placed inside the solution in the reaction tank 29. One end of the salt bridge 26 and the saturated calomel electrode 28 are both fixed inside the solution in the reaction tank 29, and the other end is fixed inside the beaker 27 containing saturated KCl solution outside the reaction tank 29, forming a structure as shown below. Figure 4 The high-temperature nitric acid reference electrode is shown; the working electrode, platinum electrode 22 and reference electrode are connected to the electrochemical workstation 32 via wire I33. The platinum electrode 22 and salt bridge 26 are 3-4 cm away from the heat-resistant glass tube heating tube of the temperature control system.

[0027] In this embodiment, the electrical control system includes a temperature control module and a load loading control module. The temperature control module is connected to the temperature sensor 25 and the heating control circuit via wire III35, and is used to record and control the real-time temperature of the solution in the reaction tank 29 and control the output power of the heat-resistant glass tube heating tube 24. The load loading control module is connected to the control panel of the tension-compression-torsion integrated testing machine 1 via wire II34, and is used to control the load type and load size, and control the start and stop of the tension-compression-torsion integrated testing machine 1.

[0028] In this embodiment, the sealing kits located at both ends of the integrated tensile-compression-torsion testing machine for sealing the specimen and the corrosion reaction area adopt a structure of through-wall flange plate combined with universal sleeve, such as... Figure 3As shown, the specific components include: pure titanium clamp I5, machined PTFE universal sleeve I6, PTFE fastening nut I7, expanded PTFE sealing ring I8, expanded PTFE sealing ring II9, PTFE flange plate I10, machined PTFE universal sleeve II11, pure titanium clamp II12, pure titanium clamp III13, machined PTFE universal sleeve III14, PTFE flange plate II15, expanded PTFE sealing ring III16, PTFE fastening nut II17, expanded PTFE sealing ring IV18, machined PTFE universal sleeve IV19, and pure titanium clamp IV20. The sealing components at both ends are symmetrical.

[0029] In this embodiment, before assembling the experimental apparatus, the heating tube 24 is first placed into the reaction tank 29, and then the following sample sealing and fixing operations are performed: Inside the reaction tank 29, the expanded polytetrafluoroethylene (ePTFE) sealing ring II8 is placed at the opening in the tank wall of the reaction tank 29. The PTFE flange plate I10 passes through the center of the ePTFE sealing ring II9 through the opening in the tank wall of the reaction tank 29, and the sample 4 passes through the center opening of the PTFE flange plate I10. The machined PTFE universal sleeve II11 is then wrapped around the PTFE flange plate I10 and the sample 4, with one end scooped through the ePTFE sealing ring II9 and pressed tightly against the inner wall. The other end of the machined PTFE universal sleeve II11 is then... The end clamp, made of pure titanium, is used to tighten the sleeve of the machined PTFE universal sleeve II11 to the sample 4. Outside the reaction tank 29, the expanded PTFE sealing ring I8 is fitted onto the PTFE flange plate I10, which passes through the tank wall of the reaction tank 29 and is tightly against the outer wall of the reaction tank 29. The large opening end of the machined PTFE universal sleeve I6 passes through the sample 4 and is tightly against the expanded PTFE sealing ring I8. A PTFE fastening nut I7 is used to tighten the machined PTFE universal sleeve I6 through the external thread of the PTFE flange plate I10 from inside the machined PTFE universal sleeve I6, securing it in place. The small opening end of the machined PTFE universal sleeve I6 is then tightened to the sample 4 using a pure titanium clamp I5. The sealing and fixing of the other end of the tension-compression-torsion integrated testing machine is the same as described above.

[0030] After sealing, adjust the six-jaw chuck I3 and six-jaw chuck II21 to clamp the sample 4. Pour the required solution into the reaction tank 29 until the liquid level covers the sample. Install the expanded polytetrafluoroethylene sealing ring 30 and the reaction tank cover 31 on the top of the reaction tank 29 in sequence. Connect and fix the condenser tube 23, platinum electrode 22, high-temperature nitric acid reference electrode, pipe heating tube 24, and temperature sensor 25 to the corresponding holes of the reaction tank cover 31. Connect the installed condenser tube 23 to a beaker containing dilute NaOH solution. Connect the electrochemical workstation placed in the electromagnetic shielding box 37 to the three-electrode system through the wire I33. This completes the connection of the corrosion reaction system, electrochemical system, exhaust gas emission system, and load loading system.

[0031] This experimental setup can simulate the stress corrosion behavior of materials under high-temperature nitric acid conditions. It can simultaneously perform stress corrosion loading and in-situ electrochemical testing of materials under high-temperature nitric acid conditions, and obtain information such as corrosion potential and corrosion current in real time, enabling rapid evaluation of materials. It can provide data and technical support for stress corrosion life assessment and online corrosion monitoring of related components.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope defined by the claims of the present invention.

Claims

1. A simulation experimental apparatus for high-temperature nitric acid full-stress corrosion of spent fuel reprocessing, characterized in that: The system includes a load loading system, a corrosion reaction system, an electrochemical testing system, a temperature control system, a tail gas treatment system, and an electrical control system. The load loading system is used for applying various loads and is connected to the electrical control system, which sets the type of load applied to the sample and controls the load magnitude. The corrosion reaction system consists of a glass reaction tank and a tank cover with a central opening. Nitric acid solution is placed in the glass reaction tank for the corrosion reaction of the sample. The sample used for the corrosion reaction passes through the glass reaction tank and is sealed by a sealing kit. The electrochemical testing system is located inside the tank cover and is connected to the electrical control system for electrochemical testing of the sample corrosion reaction. The temperature control system is connected to the electrical control system and is used to regulate and control the temperature of the sample corrosion reaction during the load loading system. The tail gas treatment system uses a condenser pipe connected to the central opening of the tank cover to treat the tail gas generated during the sample corrosion process. The electrical control system is connected to the electrochemical testing system, the load loading system, and the temperature control system via wires. The load loading system adopts a horizontally placed tension-compression-torsion integrated testing machine, which is used to apply different types of loads to the specimen. The testing machine is fixed to the specimen by six-jaw chucks set at both ends and connected to the electrical control system through wires. The type of load and the magnitude of the load loading are controlled and set through the control panel or electrical control system of the tension-compression-torsion integrated testing machine. The glass reaction tank of the corrosion reaction system is placed on the middle section of the horizontally placed tension-compression-torsion integrated testing machine. The glass reaction tank has two holes of the same size and position facing each other on the two sides facing the load loading system. The sample passes through the center of the two holes and is sealed in the glass reaction tank by a sealing kit. The sealing kit includes: a pure titanium clamp, a machined polytetrafluoroethylene (PTFE) universal sleeve, a PTFE flange plate, an expanded PTFE sealing ring, and a PTFE fastening nut.

2. The simulation experimental apparatus for high-temperature nitric acid full-stress corrosion of spent fuel reprocessing according to claim 1, characterized in that: The test specimens are standard dumbbell-shaped tensile specimens, round bar specimens, or plate-shaped specimens fixed by special clamps.

3. The simulation experimental apparatus for high-temperature nitric acid full-stress corrosion of spent fuel reprocessing according to claim 1, characterized in that: The temperature control system includes a heat-resistant glass tube heating element, a temperature sensor, and a heating control circuit. One end of the heat-resistant glass tube heating element is inserted into the tank cover of the reaction tank, and the other end is placed in the glass reaction tank of the corrosion reaction system, 1-1.5 cm from the bottom of the tank. The temperature sensor and the heating control circuit are both placed inside the tank cover of the reaction tank and connected to the glass tube heating element and the electrical control system respectively by wires. They are used to test the temperature of the heating element and transmit the tested temperature to the electrical control system. The heat-resistant glass tube heating element is connected to the electrical control system via a heating control circuit to achieve temperature regulation and control within the reaction tank.

4. The simulation experimental apparatus for high-temperature nitric acid full-stress corrosion of spent fuel reprocessing according to claim 1, characterized in that: The electrochemical testing system includes a three-electrode system and an electrochemical workstation. The three-electrode system includes a working electrode, a counter electrode, and a high-temperature nitric acid reference electrode that pass through the reaction tank cover. The working electrode is connected to the sample and placed outside the reaction tank. The counter electrode is placed inside the reaction tank solution. One end of the high-temperature nitric acid reference electrode is placed inside the reaction tank solution, and the other end is placed outside the reaction tank. The working electrode, platinum electrode, and high-temperature nitric acid reference electrode are also connected to the electrochemical workstation via wires. The platinum electrode is 3-4 cm away from the heat-resistant glass tubular heating tube of the temperature control system.

5. The simulation experimental apparatus for high-temperature nitric acid full-stress corrosion of spent fuel reprocessing according to claim 4, characterized in that: The experimental setup also includes an electromagnetic shielding box. The electrochemical workstation in the electrochemical testing system is placed inside the electromagnetic shielding box. The side of the electromagnetic shielding box has an opening, and the electrochemical workstation is connected to the electrical control system through a wire passing through the electromagnetic shielding box.

6. The simulation experimental apparatus for high-temperature nitric acid full-stress corrosion of spent fuel reprocessing according to claim 1, characterized in that: The experimental setup also includes a fume hood, and the load loading system, corrosion reaction and electrochemical testing system, temperature control system and exhaust gas treatment system are all placed inside the fume hood.

7. The simulation experimental apparatus for high-temperature nitric acid full-stress corrosion of spent fuel reprocessing according to claim 4, characterized in that: The electrical control system includes a temperature control module and a load loading control module. The temperature control module is connected to a temperature sensor and a heating control circuit via wires. It is used to record and control the real-time temperature of the solution in the reaction tank and control the output power of the heat-resistant glass tube heating pipe. The load loading control module is connected to the control panel of the tension-compression-torsion integrated testing machine via wires. It is used to control the load type and load size, and control the start and stop of the tension-compression-torsion integrated testing machine.

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