A dissolving device

Abstract

The application relates to the technical field of nuclear fuel, and provides a dissolving device, which comprises a shell, a ring shell and a stirring piece, the shell is formed with a dissolving cavity for containing a dissolving solution; the ring shell is arranged in the dissolving cavity, the ring shell is provided with an inner wall and an outer wall, a layer is formed between the outer wall and the inner wall, the outer wall and the inner wall are both formed with an opening communicating with the layer, and spent fuel is arranged in the layer; and the stirring piece is arranged in the dissolving cavity and used for stirring the dissolving solution. The dissolving device provided by the application has a high dissolving rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear fuel, in particular to a dissolving device. BACKGROUND

[0002] The fast reactor is a reactor that uses fast neutrons to realize chain fission, and has the characteristics of greatly improving the utilization rate of radioactive element resources, transmutation of long-lived waste and inherent safety. Developing a fast reactor fuel cycle is a key link to realize the sustainable development of nuclear energy. Therefore, a device capable of dissolving spent fuel is urgently needed.

[0003] In the related art, the spent fuel is placed in a device containing a dissolving solution, and then dissolved by bubbling, which has a low dissolving rate. SUMMARY

[0004] Therefore, the embodiments of the present application aim to provide a dissolving device with a high dissolving rate.

[0005] To achieve the above-mentioned purpose, the technical scheme of the embodiments of the present application is as follows:

[0006] The embodiments of the present application disclose a dissolving device for dissolving spent fuel, comprising:

[0007] An outer shell forms a dissolving cavity containing a dissolving solution;

[0008] A ring shell is arranged in the dissolving cavity, the ring shell has an inner wall and an outer wall, a cladding layer is formed between the outer wall and the inner wall, the outer wall and the inner wall are both formed with an opening communicating with the cladding layer, and the spent fuel is arranged in the cladding layer;

[0009] A stirring member is arranged in the dissolving cavity for stirring the dissolving solution.

[0010] In an embodiment, the stirring member is arranged in the ring shell.

[0011] In an embodiment, the stirring member is a magnetic stirrer.

[0012] In an embodiment, the ring shell is detachably arranged on the cavity wall of the dissolving cavity.

[0013] In an embodiment, one of the ring shell and the cavity wall of the dissolving cavity is provided with a guide strip, and the other is provided with a guide groove, and the guide strip and the guide groove are in guiding cooperation.

[0014] In an embodiment, the dissolving device comprises a heating jacket, and the outer shell is sleeved in the heating jacket.

[0015] In an embodiment, the dissolving device comprises a heat preservation sleeve, and the heating sleeve is sleeved in the heat preservation sleeve.

[0016] In an embodiment, the dissolving device comprises a pressure sensor, a pressure relief valve and a controller, the controller is connected with the pressure sensor and the pressure relief valve respectively, the pressure sensor is used to acquire the pressure in the dissolving cavity, the pressure relief valve is connected with the dissolving cavity and the outside, and the controller is configured to control the pressure relief valve to open or close according to the pressure value of the pressure sensor.

[0017] In an embodiment, the dissolving device comprises a sampling pipe, a first valve and a second valve, the sampling pipe is connected with the dissolving cavity and the outside, and the first valve and the second valve are arranged at the middle part and the end close to the outside of the sampling pipe respectively.

[0018] In an embodiment, the spent fuel is plutonium uranium mixed oxide fuel.

[0019] The embodiment of the present application discloses a dissolving device, which is characterized in that a dissolving cavity is arranged in the shell, so that the internal parts can be protected to some extent, the service life is improved, and the impurities introduced by dust and the like entering the dissolving cavity are reduced. The ring shell and the stirring part are arranged in the dissolving cavity, the inner wall and the outer wall of the ring shell form a layer, the spent fuel is arranged in the layer, and the stirring part is arranged in the dissolving cavity and used for stirring the dissolving liquid. In this way, the stirring part can make the dissolving liquid enter the layer and contact the spent fuel through one of the openings in the inner wall and the openings in the outer wall, and then flow out from the other one of the openings in the inner wall and the openings in the outer wall. In this way, the solid-liquid contact area and the solid-liquid relative movement rate can be greatly improved, so that the dissolving rate of the spent fuel can be greatly improved, and the error caused by uneven dissolving can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 FIG. 1 is a structural schematic diagram of a dissolving device according to an embodiment of the present application;

[0021] Figure 2 FIG. 2 is a structural schematic diagram of a ring shell according to another embodiment of the present application;

[0022] Figure 3 FIG. 3 is a structural schematic diagram of a ring shell according to still another embodiment of the present application; Figure 1 FIG. 4 is a structural schematic diagram from another perspective;

[0023] Figure 4 FIG. 5 is a structural schematic diagram of a ring shell and a guide strip according to still another embodiment of the present application;

[0024] Figure 5 FIG. 6 is a structural schematic diagram of a ring shell in FIG. 5; Figure 4

[0025] Figure 6 ​For Figure 5 Structural schematic diagram from another perspective

[0026] Figure 7 Structural schematic diagram of a guide strip provided for another embodiment of the application.

[0027] Legend of reference signs

[0028] 100, dissolving device; 1, shell; 1a, dissolving cavity; 1b, sampling port; 11, shell body; 12, cover body; 2, ring shell; 2a, opening; 2b, mounting lug; 2b1, limiting arm; 2b2, limiting groove; 2c, handle; 21, inner wall; 22, outer wall; 3, stirring piece; 4, heating jacket; 5, heat preservation jacket; 6, pressure sensor; 7, pressure relief valve; 8, air supplement valve; 9, pressure gauge; 10, temperature sensor; A, guide strip; A1, limiting column; A2, guide block; A3, stop block. DETAILED DESCRIPTION

[0029] It should be noted that the embodiments and technical features in the application can be combined with each other without conflict, and the detailed description in the specific embodiments should be understood as an explanation and description of the purpose of the application, and should not be regarded as an improper limitation on the application.

[0030] The application will be further described in detail below in combination with the drawings and specific embodiments. The "first", "second" and the like in the embodiments of the application are only for the purpose of description, and should not be understood as indicating or implying their relative importance or implicitly including at least one feature. In the description of the embodiments of the application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0031] The embodiments of the application provide a dissolving device 100 for dissolving spent fuel. Please refer to Figures 1 to 7 The dissolving device 100 includes a shell 1, a ring shell 2 and a stirring piece 3. The shell 1 is formed with a dissolving cavity 1a for containing a dissolving solution. The ring shell 2 is arranged in the dissolving cavity 1a, and the ring shell 2 has an inner wall 21 and an outer wall 22, and a layer is formed between the outer wall 22 and the inner wall 21. The outer wall 22 and the inner wall 21 are both formed with an opening 2a in communication with the layer, and the spent fuel is arranged in the layer. The stirring piece 3 is arranged in the dissolving cavity 1a, and is used for stirring the dissolving solution.

[0032] The dissolving device 100 provided in the application can protect the internal components to some extent, improve the service life, and reduce the entry of dust and other impurities into the dissolving cavity 1a. The annular shell 2 and the stirring piece 3 are arranged in the dissolving cavity 1a, the inner wall 21 and the outer wall 22 of the annular shell 2 form a layer, the spent fuel is arranged in the layer, and the stirring piece 3 is arranged in the dissolving cavity 1a and used for stirring the dissolving liquid. In this way, the stirring piece 3 can make the dissolving liquid enter the layer and contact the reflective fuel through one of the openings 2a on the inner wall 21 and the openings 2a on the outer wall 22, and then flow out from the other one of the openings 2a on the inner wall 21 and the openings 2a on the outer wall 22. In this way, the solid-liquid contact area and the solid-liquid relative movement rate can be greatly improved, and the dissolving rate of the spent fuel can be greatly improved, and the error caused by uneven dissolving can be reduced.

[0033] For example, in an embodiment, referring to Figure 1 and Figure 2 The shape of the annular shell 2 is not limited, for example, it can be a hollow cylinder, and the curved surface structure design of the inner wall 21 and the outer wall 22 is adapted to the flow state of the dissolving liquid during stirring, so as to reduce the resistance of the dissolving liquid during flow.

[0034] For example, in an embodiment, the spent fuel can be the nuclear fuel discharged from a fast reactor.

[0035] For example, in an embodiment, the dissolving liquid can be nitric acid.

[0036] In an embodiment, the spent fuel can be plutonium-uranium oxide mixed fuel (MOX).

[0037] For example, in an embodiment, Figure 1 R1 can be the inner-outer direction, and R2 can be the up-down direction.

[0038] It should be noted that the fast reactor is a reactor that uses fast neutrons to realize chain fission, has the characteristics of greatly improving the utilization rate of uranium resources, long-life waste transmutation and inherent safety, and developing fast reactor fuel cycle is a key link to realize the sustainable development of nuclear energy. The plutonium-uranium oxide mixed fuel is used as the nuclear fuel in the fast reactor. Therefore, in order to realize the fast reactor fuel cycle, the spent fuel of the fast reactor must be treated to recover the plutonium in the spent fuel of the fast reactor as soon as possible.

[0039] MOX fuel is a uranium plutonium oxide fuel composed of uranium dioxide and plutonium dioxide. The MOX fuel used in fast reactors contains 20% to 30% of plutonium dioxide, and a high content of plutonium in MOX can cause nuclear criticality in the nitric acid dissolution process, resulting in an increase in insoluble residue and a decrease in dissolution rate. In the related art, hydrogen fluoride and electrochemical oxidation methods are used for enhanced dissolution, but these methods will introduce other chemicals, making the subsequent extraction process complex. In the present application, the ring shell 2 is matched with the stirring piece 3, the ring shell 2 is formed with a sandwich layer, and the spent fuel is arranged in the sandwich layer. In this way, after the dissolution liquid is stirred by the stirring piece 3, it can enter the sandwich layer through the circumferential opening 2a to contact the spent fuel, thereby increasing the contact area of the dissolution liquid and the spent fuel and the relative motion rate between the flowing dissolution liquid and the spent fuel to accelerate the dissolution rate.

[0040] In an embodiment, the size of the opening 2a needs to be determined according to the particle size of the spent fuel and the flow condition of the liquid phase material in the dissolution cavity 1a.

[0041] For example, the maximum size of the opening 2a can be determined according to the particle size distribution of the spent fuel to reduce the outflow of the spent fuel placed in the sandwich layer during the dissolution process. Secondly, during the process of placing the spent fuel into the ring shell 2, it is necessary to ensure that the spent fuel particles of different sizes can be filled more fully and closely to prevent the spent fuel particles from moving significantly under the scouring of the dissolution liquid. Thirdly, the size of the opening 2a cannot be too small, otherwise it will cause a large resistance to the dissolution liquid in the dissolution cavity 1a, causing the dissolution liquid to fail to pass through the opening 2a into the sandwich layer, thereby reducing the renewal rate of the dissolution liquid on the surface of the spent fuel and affecting the dissolution rate. Finally, the size of the opening 2a can be determined by numerically simulating the flow condition of the solution in the dissolution device 100 to obtain an optimal size of the opening 2a. For example, for a larger dissolution device 100, particles of different sizes have different suspension heights during the suspension of the spent fuel. At this time, the size of the opening 2a in the axial direction of the different dissolution devices 100 can be determined according to the flow field structure, solid content rate and particle size distribution characteristics of the spent fuel in the dissolution device 100.

[0042] In an embodiment, please refer to Figure 1 , the stirring piece 3 is arranged in the ring shell 2. For example, the stirring piece 3 can be arranged at the center of the ring shell 2 and close to the bottom of the dissolution cavity 1a. In this way, by arranging the stirring piece 3 in the ring shell 2, the stirred dissolution liquid can be sent into the sandwich layer from the circumferential opening 2a to increase the contact area with the spent fuel. Moreover, by arranging the stirring piece 3 in the ring shell 2, the dissolution liquid can be stirred into the sandwich layer more quickly, further increasing the relative motion rate of the spent fuel and the dissolution liquid, thereby further increasing the dissolution rate.

[0043] In an embodiment, the stirring member 3 is a magnetic stirrer. In this way, on the one hand, the magnetic stirring method can provide the reaction between the dissolving solution and the spent fuel, so that the spent fuel can be fully dissolved, and the error caused by uneven dissolution can be reduced; on the other hand, the magnetic stirrer is stirred by magnetic force, so that the sealing of the dissolving device 100 during the dissolving process can be ensured, and the situation that the mechanical stirring needs to be strictly sealed can be reduced, so that the structure of the dissolving device 100 can be simplified.

[0044] In an embodiment, referring to Figure 4 , the ring shell 2 is detachably arranged on the cavity wall of the dissolving cavity 1a. In this way, on the one hand, after the ring shell 2 is arranged on the cavity wall of the dissolving cavity 1a, the situation that the ring shell 2 rotates circumferentially under the flow of the dissolving solution can be reduced; on the other hand, the detachable manner facilitates the disassembly and assembly of the ring shell 2, and facilitates the pouring out of the residual impurities in the ring shell 2 after the dissolving is completed.

[0045] In an embodiment, referring to Figure 1 , the shell 1 includes a shell body 11 and a cover body 12, the shell body 11 is formed with the dissolving cavity 1a and a mounting opening communicating with the dissolving cavity 1a, and the cover body 12 is rotatably connected with the shell body 11 and can open or close the mounting opening.

[0046] In an embodiment, referring to Figure 4 , one of the ring shell 2 and the cavity wall of the dissolving cavity 1a is provided with a guide strip A, and the other is provided with a guide groove, and the guide strip A and the guide groove are in guiding cooperation.

[0047] For example, the outer side of the ring shell 2 can be provided with the guide strip A, and the circumferential cavity wall of the dissolving cavity 1a is provided with the guide groove extending in the up-down direction. By arranging the guide strip A and the guide groove, the guide groove can provide a smooth and accurate moving path, and the guide strip A can easily slide in the guide groove, so that the whole moving process is more accurate and controllable; on the other hand, the guide groove can provide additional support and stability to avoid the situation that the guide strip A shakes or slides unstably during the moving process, and the moving is stable, and after the guide groove cooperates with the guide strip A, the circumferential rotation of the ring shell 2 under the fluid action of the dissolving solution can be reduced.

[0048] For example, in an embodiment, referring to Figures 4 to 7The outer circumferential surface of the ring shell 2 is provided with three mounting ears 2b, and the number of the guide strips A can be three. The three mounting ears 2b are arranged at intervals of 120°, and each mounting ear 2b includes two limiting arms 2b1 arranged at intervals in the circumferential direction to form a limiting groove 2b2. Each baffle is arranged at one end in the radial direction of the ring shell 2 in one limiting groove 2b2, and the other end in the radial direction of the ring shell 2 is matched with the guide groove on the circumferential cavity wall of the dissolving cavity 1a. In this way, the guiding stability of the ring shell 2 and the shell 1 can be further increased, and the working stability of the ring shell 2 when stirred by the stirring piece 3 can also be further increased.

[0049] In other embodiments, referring to Figures 4 to 7 The outer circumferential surface of the ring shell 2 is provided with six mounting ears 2b, and three of the six mounting ears 2b are arranged at intervals of 120° at one end of the ring shell 2 in the up-down direction, and the other three are arranged at intervals of 120° at the other end of the ring shell 2 in the up-down direction. Each mounting ear 2b includes two limiting arms 2b1 arranged at intervals in the circumferential direction to form a limiting groove 2b2. Each baffle is arranged at one end in the radial direction of the ring shell 2 in a pair of limiting grooves 2b2 in the up-down direction, and the other end in the radial direction of the ring shell 2 is matched with the guide groove on the circumferential cavity wall of the dissolving cavity 1a. In this way, the guiding stability and working stability of the ring shell 2 can be further improved.

[0050] For example, in an embodiment, referring to Figure 4 and Figure 7 The lower end of the guide strip A is provided with a limiting column A1. During the process of inserting the guide strip A upward into the limiting groove 2b2, the limiting column A1 at the lower end of the guide strip A abuts against the bottom surface of the mounting ear 2b at the lower end of the ring shell 2, and then the guide strip A and the ring shell 2 are inserted into the guide groove together.

[0051] For example, in an embodiment, referring to Figure 4 The lower end of the guide strip A is provided with a guide block A2, and the size of the guide block A2 in the radial direction of the ring shell 2 gradually increases from bottom to top. In this way, the guide block A2 can be used as a guide when the guide strip A is inserted into the guide groove.

[0052] For example, in an embodiment, referring to Figure 4 The upper end of the guide strip A is provided with a stop block A3, which can abut against the top surface of the limiting groove 2b2 after the guide strip A is inserted into the guide groove.

[0053] For example, in an embodiment, referring to Figure 1The dissolving device 100 comprises a heating jacket 4, and the shell 1 is sleeved in the heating jacket 4. In this way, the dissolving cavity 1a can be heated in the circumferential direction, which can increase the kinetic energy of the molecules, so that the solute molecules are more easily separated from the surface of the spent fuel and mixed with the dissolving liquid, thereby accelerating the dissolving rate; on the other hand, the circumferential heating can provide a consistent heat source around the dissolving cavity 1a, which is helpful for uniform heating, thereby reducing the occurrence of local overheating caused by uneven reaction.

[0054] For example, in an embodiment, the heating jacket 4 can be an electric heating jacket 4, and the temperature can be adjusted as needed.

[0055] In an embodiment, referring to Figure 4 The dissolving device 100 comprises a heat preservation jacket 5, and the heating jacket 4 is sleeved in the heat preservation jacket 5. In this way, the shell 1 can be heat preserved, and heat loss can be reduced to ensure that the dissolving process is quickly carried out.

[0056] In an embodiment, referring to Figure 1 and Figure 2 The ring shell 2 is provided with a handle 2c. In this way, by providing the handle 2c, the operator can put the ring shell 2 into the dissolving cavity 1a or take it out of the dissolving cavity 1a by holding the handle 2c, which is convenient and efficient.

[0057] In an embodiment, referring to Figure 3 The dissolving device 100 comprises a pressure sensor 6, a pressure relief valve 7 and a controller, the controller is in communication connection with the pressure sensor 6 and the pressure relief valve 7 respectively, the pressure sensor 6 is used to obtain the pressure in the dissolving cavity 1a, the pressure relief valve 7 is communicated with the dissolving cavity 1a and the outside, and the controller is configured to be able to control the pressure relief valve 7 to open or close according to the pressure value of the pressure sensor 6.

[0058] For example, the pressure sensor 6 and the pressure relief valve 7 can be arranged on the cover body 12, the pressure sensor 6 can obtain the pressure in the dissolving cavity 1a, and the pressure relief valve 7 is communicated with the dissolving cavity 1a and the outside. The controller can be a PLC system. The controller can be in communication connection with the pressure sensor 6 and the pressure relief valve 7 in a wireless or wired manner. In this way, when the pressure sensor 6 detects that the pressure of the dissolving cavity 1a reaches a threshold pressure, the pressure sensor 6 will send a pressure overload signal to the controller, and the controller will control the pressure relief valve 7 to open after receiving the signal, so as to relieve the pressure of the dissolving cavity 1a and reduce the risk of explosion caused by excessive pressure.

[0059] In an embodiment, referring to Figure 3The dissolving device 100 comprises a gas supplement valve 8, which is connected with the dissolving cavity 1a and the outside, and is connected with the controller. In this way, when the pressure sensor 6 detects that the pressure in the dissolving cavity 1a is lower than the set pressure, the pressure sensor 6 sends a signal to the controller, and the controller controls the gas supplement valve 8 to supplement gas to the dissolving cavity 1a, so that the pressure in the dissolving cavity 1a reaches the set pressure, and the dissolving rate can be further accelerated.

[0060] For example, in an embodiment, referring to Figure 1 and Figure 3 The dissolving device 100 comprises a pressure gauge 9, which can be arranged on the cover 12 and is used to detect the pressure in the dissolving cavity 1a. The pressure gauge 9 and the pressure sensor 6 can be connected with the controller, so as to double-ensure that the pressure is not too high and out of control.

[0061] For example, in an embodiment, referring to Figure 3 The dissolving device 100 comprises a temperature sensor 10, which is used to monitor the temperature in the dissolving cavity 1a. The temperature sensor 10 and the heating jacket 4 can be connected with the controller. In this way, when the temperature sensor 10 detects that the temperature in the dissolving cavity 1a is lower than the set temperature or higher than the set temperature, the temperature sensor 10 sends a signal to the controller, and the controller controls the heating jacket 4 to regulate the temperature in the dissolving cavity 1a, so that the automation degree is high.

[0062] In an embodiment, the dissolving device 100 comprises a sampling pipe, a first valve and a second valve. The sampling pipe is connected with the dissolving cavity 1a and the outside. The first valve and the second valve are arranged at the middle part and the end close to the outside of the sampling pipe respectively.

[0063] For example, the shell 1 is formed with a sampling port connected with the dissolving cavity 1a. One end of the sampling pipe is located in the dissolving cavity 1a, and the other end of the sampling pipe is connected with the outside through the sampling port. The first valve can be arranged at the middle part of the sampling pipe, and the second valve can be arranged at the end of the sampling pipe close to the sampling port. In this way, when sampling and detection are performed, the first valve and the second valve can be opened. The pressure in the dissolving cavity 1a makes part of the dissolving solution flow into the sampling pipe. Then, the first valve is closed, the dissolving solution in the sampling pipe is separated from the dissolving cavity 1a, and the dissolving solution between the first valve and the second valve is depressurized, cooled and sampled. After sampling is completed, the first valve is opened and the second valve is closed, so that the dissolving solution in the sampling pipe flows back to the dissolving cavity 1a. In this way, two-stage sampling is adopted, and sampling can be performed in the high-temperature and high-pressure dissolving reaction process, and the safety is high.

[0064] The above descriptions are only the preferred embodiments of the present application, not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A dissolver for dissolving spent fuel, characterized by, The dissolution device comprises: a shell, which forms a dissolution cavity for accommodating a dissolution solution; a ring shell, which is arranged in the dissolution cavity, has an inner wall and an outer wall, and has a sandwich layer formed between the outer wall and the inner wall, the outer wall and the inner wall are both formed with an opening communicating with the sandwich layer, and the spent fuel is arranged in the sandwich layer; a stirring member, which is arranged in the dissolution cavity and is used for stirring the dissolution solution.

2. The dissolving apparatus according to claim 1, wherein The stirring member is arranged in the ring shell.

3. The dissolving apparatus of claim 1, wherein The stirring member is a magnetic stirrer.

4. The dissolution apparatus of claim 1, wherein, The ring shell is detachably arranged in the cavity wall of the dissolution cavity.

5. The dissolution apparatus of claim 4, wherein, One of the ring shell and the cavity wall of the dissolution cavity is provided with a guide strip, and the other is provided with a guide groove, and the guide strip and the guide groove are in guided cooperation.

6. The dissolution apparatus of claim 1, wherein, The dissolution device comprises a heating jacket, and the shell is sleeved in the heating jacket.

7. The dissolution apparatus of claim 6, wherein, The dissolution device comprises an insulation jacket, and the heating jacket is sleeved in the insulation jacket.

8. The dissolution apparatus of claim 1, wherein, The dissolution device comprises a pressure sensor, a pressure relief valve and a controller, the controller is in communication connection with the pressure sensor and the pressure relief valve respectively, the pressure sensor is used for acquiring the pressure in the dissolution cavity, the pressure relief valve communicates the dissolution cavity with the outside world, and the controller is configured to be capable of controlling the pressure relief valve to be opened or closed according to the pressure value of the pressure sensor.

9. The dissolution apparatus of claim 1, wherein, The dissolution device comprises a sampling pipe, a first valve and a second valve, the sampling pipe communicates the dissolution cavity with the outside world, and the first valve and the second valve are arranged at the middle part and the end close to the outside world of the sampling pipe respectively.

10. The dissolution apparatus of claim 1, wherein, The spent fuel is plutonium-uranium oxide mixed fuel.

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