Dissolving device

Abstract

The invention relates to the technical field of nuclear fuel, and provides a dissolving device which comprises a shell, an annular shell and a stirring piece, and a dissolving cavity for containing a dissolving solution is formed in the shell; the annular shell is arranged in the dissolving cavity, the annular shell is provided with an inner wall and an outer wall, an interlayer is formed between the outer wall and the inner wall, open holes communicated with the interlayer are formed in the outer wall and the inner wall, and the spent fuel is arranged in the interlayer; the stirring part is arranged in the dissolving cavity and used for stirring the dissolving solution. The dissolving device provided by the invention is relatively high in dissolving rate.

Description

Technical Field

[0001] The present application relates to the field of nuclear fuel technology, and in particular to a dissolution device. Background Art

[0002] Fast reactors are reactors that use fast neutrons to achieve chain fission reactions. They have the characteristics of greatly improving the utilization rate of radioactive element resources, transmuting long-lived waste and inherent safety. The development of fast reactor fuel cycles is a key link in achieving sustainable development of nuclear energy. Therefore, there is an urgent need for a device that can dissolve spent fuel.

[0003] In the related art, the spent fuel is placed in a device containing a dissolving liquid and then dissolved by bubbling, and the dissolution rate is low. Summary of the invention

[0004] In view of this, the embodiments of the present application hope to provide a dissolution device with a higher dissolution rate.

[0005] In order to achieve the above-mentioned purpose, the technical solution of the embodiment of the present application is implemented as follows:

[0006] The embodiment of the present application discloses a dissolution device for dissolving spent fuel, comprising:

[0007] The shell is formed with a dissolving cavity for containing the dissolving liquid;

[0008] an annular shell, arranged in the dissolution chamber, the annular shell having an inner wall and an outer wall, an interlayer formed between the outer wall and the inner wall, the outer wall and the inner wall both forming openings communicating with the interlayer, the spent fuel being arranged in the interlayer;

[0009] A stirring member is arranged in the dissolving chamber and is used for stirring the dissolving liquid.

[0010] In one embodiment, the stirring member is disposed in the annular shell.

[0011] In one embodiment, the stirring element is a magnetic stirrer.

[0012] In one embodiment, the annular shell is detachably arranged on the cavity wall of the dissolution cavity.

[0013] In one embodiment, one of the annular shell and the cavity wall of the dissolution chamber is provided with a guide strip, and one of the annular shell and the cavity wall of the dissolution chamber is provided with a guide groove, and the guide strip cooperates with the guide groove in a guiding manner.

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

[0015] In one embodiment, the dissolving device comprises a thermal insulation sleeve, and the heating sleeve is arranged in the thermal insulation sleeve.

[0016] In one embodiment, the dissolution device includes a pressure sensor, a pressure relief valve and a controller, wherein the controller is communicatively connected to the pressure sensor and the pressure relief valve respectively, the pressure sensor is used to obtain the pressure in the dissolution chamber, the pressure relief valve connects the dissolution chamber with the outside world, 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 one embodiment, the dissolution device includes a sampling tube, a first valve and a second valve. The sampling tube connects the dissolution chamber and the outside world. The first valve and the second valve are respectively arranged in the middle of the sampling tube and at one end close to the outside world.

[0018] In one embodiment, the spent fuel is a plutonium-uranium oxide mixed fuel.

[0019] The embodiment of the present application discloses a dissolution device, which can not only protect its internal parts to a certain extent and improve its service life by providing a dissolution chamber in the shell, but also reduce the introduction of impurities such as dust into the dissolution chamber. By providing an annular shell and a stirring member in the dissolution chamber, an interlayer is formed between the inner wall and the outer wall of the annular shell, the spent fuel is provided in the interlayer, and the stirring member is provided in the dissolution chamber for stirring the dissolved liquid. In this way, the stirring member can allow the dissolved liquid to enter the interlayer through one of the openings on the inner wall and the openings on the outer wall to contact the reflective fuel, and then flow out from the other of the openings on the inner wall and the openings on the outer wall. In this way, the solid-liquid contact area and the relative movement rate of the solid-liquid can be greatly increased, thereby greatly increasing the dissolution rate of the spent fuel and reducing the error caused by uneven dissolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the structure of a dissolving device provided in an embodiment of the present application;

[0021] Figure 2 A schematic diagram of the structure of a ring shell provided in another embodiment of the present application;

[0022] Figure 3 for Figure 1 Schematic diagram of the structure from another perspective;

[0023] Figure 4 A schematic diagram of the structure of a ring shell and a guide strip provided in yet another embodiment of the present application;

[0024] Figure 5 for Figure 4 Schematic diagram of the structure of the ring shell;

[0025] Figure 6for Figure 5 Schematic diagram of the structure from another perspective;

[0026] Figure 7 A schematic structural diagram of a guide strip provided in yet another embodiment of the present application.

[0027] Description of Reference Numerals

[0028] 100. Dissolution device; 1. Outer shell; 1a. Dissolution chamber; 1b. Sampling port; 11. Shell; 12. Cover; 2. Ring shell; 2a. Opening; 2b. Mounting ear; 2b1. Limit arm; 2b2. Limit groove; 2c. Handle; 21. Inner wall; 22. Outer wall; 3. Stirring element; 4. Heating sleeve; 5. Insulation sleeve; 6. Pressure sensor; 7. Pressure relief valve; 8. Air supply valve; 9. Pressure gauge; 10. Temperature sensor; A. Guide strip; A1. Limit column; A2. Guide block; A3. Stop block. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments and technical features in the embodiments of the present application can be combined with each other, and the detailed description in the specific implementation method should be understood as an explanation of the purpose of the present application and should not be regarded as an improper limitation on the present application.

[0030] The present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The descriptions of "first", "second", etc. in the embodiments of the present application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly including at least one feature. In the description of the embodiments of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically limited.

[0031] The present application embodiment provides a dissolution device 100 for dissolving spent fuel. Figures 1 to 7 The dissolution device 100 includes an outer shell 1, an annular shell 2 and a stirring member 3. The outer shell 1 forms a dissolution chamber 1a for accommodating a dissolving liquid. The annular shell 2 is disposed in the dissolution chamber 1a, and the annular shell 2 has an inner wall 21 and an outer wall 22. An interlayer 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 connected to the interlayer, and the spent fuel is disposed in the interlayer. The stirring member 3 is disposed in the dissolution chamber 1a for stirring the dissolving liquid.

[0032] The dissolution device 100 provided in the present application can not only protect its internal components to a certain extent and improve its service life by providing a dissolution chamber 1a in the housing 1, but also reduce the introduction of impurities such as dust into the dissolution chamber 1a. By providing an annular shell 2 and a stirring member 3 in the dissolution chamber 1a, an interlayer is formed between the inner wall 21 and the outer wall 22 of the annular shell 2, the spent fuel is provided in the interlayer, and the stirring member 3 is provided in the dissolution chamber 1a for stirring the dissolved liquid. In this way, the stirring member 3 can allow the dissolved liquid to enter the interlayer through one of the openings 2a on the inner wall 21 and the openings 2a on the outer wall 22 to contact the reflective fuel, and then flow out from the other 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 relative movement rate of the solid-liquid can be greatly increased, thereby greatly increasing the dissolution rate of the spent fuel and reducing the error caused by uneven dissolution.

[0033] For example, in one embodiment, please refer 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 structural design of the inner wall 21 and the outer wall 22 is adapted to the flow state of the dissolved liquid during stirring to reduce the resistance of the dissolved liquid during flow.

[0034] Illustratively, in one embodiment, the spent fuel may be nuclear fuel discharged from a fast reactor.

[0035] Exemplarily, in one embodiment, the dissolving liquid may be nitric acid.

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

[0037] Exemplarily, in one embodiment, Figure 1 R1 can be the inside-outside direction, and R2 can be the top-bottom direction.

[0038] It should be noted that fast reactors are reactors that use fast neutrons to achieve chain fission reactions. They have the characteristics of greatly improving the utilization rate of uranium resources, transmuting long-life waste, and inherent safety. The development of fast reactor fuel cycles is a key link in achieving sustainable development of nuclear energy. Fast reactors use plutonium-uranium oxide mixed fuel as nuclear fuel. Therefore, in order to realize the fast reactor fuel cycle, it is necessary to realize the reprocessing of fast reactor spent fuel to recover the plutonium in fast reactor spent fuel 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% plutonium dioxide, and the high plutonium content in MOX can lead to nuclear criticality during the nitric acid dissolution process, resulting in an increase in insoluble residues and a slower dissolution rate. In the related art, hydrofluoric acid and electrochemical oxidation methods are used to enhance dissolution, but these methods will introduce other chemical substances, making the subsequent extraction process complicated. In the present application, the annular shell 2 is matched with the stirring member 3, and the annular shell 2 is formed with an interlayer, and the spent fuel is arranged in the interlayer. In this way, after the dissolving liquid is stirred by the stirring member 3, it can enter the interlayer along the circumferential opening 2a to contact the spent fuel, thereby increasing the contact area between the dissolving liquid and the spent fuel, and the flowing dissolving liquid can increase the relative movement rate between the spent fuel and the spent fuel to accelerate the dissolution rate.

[0040] In one embodiment, the size of the opening 2a needs to be determined according to the material particles of the spent fuel and the flow conditions of the liquid phase material in the dissolution chamber 1a.

[0041] For example, the maximum size of the opening 2a can be determined according to the particle size distribution of the spent fuel material to reduce the outflow of the spent fuel contained in the interlayer during the dissolution process; secondly, in the process of placing the spent fuel into the annular shell 2, it is necessary to ensure that the spent fuel particles of different sizes can be filled relatively fully and tightly to ensure that the spent fuel particles will not move significantly under the flushing of the dissolving liquid; thirdly, the size of the opening 2a cannot be too small. A too small size of the opening 2a will produce a large resistance to the dissolving liquid in the dissolving cavity 1a, causing the dissolving liquid to be unable to smoothly pass through the opening 2a into the interlayer , thereby reducing the renewal speed of the dissolved liquid on the surface of the spent fuel, and then affecting the dissolution rate; finally, the size of the opening 2a can be determined by simulating the flow condition of the solution in the dissolving device 100 in a numerical simulation manner to obtain a better size of the opening 2a. For example, for a larger dissolving device 100, particles of different particle sizes have different suspension heights during the spent fuel suspension process. At this time, the size of the opening 2a in the axial direction of different dissolving devices 100 can be determined based on the flow field structure and solid content in the dissolving device 100 and the spent fuel particle size distribution characteristics.

[0042] In one embodiment, please refer to Figure 1 , the stirring member 3 is arranged in the annular shell 2. Exemplarily, the stirring member 3 can be arranged in the center of the annular shell 2 and close to the bottom of the dissolution chamber 1a. In this way, by arranging the stirring member 3 in the annular shell 2, the stirred solution can be sent into the interlayer from the opening 2a along the circumferential direction, thereby increasing the contact area with the spent fuel. Moreover, by arranging the stirring member 3 in the annular shell 2, the solution can be stirred into the interlayer more quickly, further increasing the relative movement rate between the spent fuel and the solution, and then further increasing the dissolution rate.

[0043] In one embodiment, the stirring member 3 is a magnetic stirrer. Thus, on the one hand, the magnetic stirring method can provide a reaction between the dissolving liquid and the spent fuel, so that the spent fuel can be fully dissolved, while reducing the error caused by uneven dissolution; on the other hand, the magnetic stirrer stirs by magnetic force, so that the dissolving device 100 can be fully sealed during the dissolution process, reducing the situation that mechanical stirring requires strict sealing, thereby simplifying the structure of the dissolving device 100.

[0044] In one embodiment, please refer to Figure 4 The ring shell 2 is detachably mounted on the wall of the dissolving chamber 1a. Thus, on the one hand, after the ring shell 2 is mounted on the wall of the dissolving chamber 1a, the circumferential rotation of the ring shell 2 under the flow of the dissolving liquid can be reduced; on the other hand, the detachable manner makes it easy to disassemble and install the ring shell 2, and to pour out the residual impurities in the ring shell 2 after the dissolution is completed.

[0045] In one embodiment, please refer to Figure 1 The housing 1 includes a shell 11 and a cover 12. The shell 11 is formed with a dissolution chamber 1a and a mounting port communicating with the dissolution chamber 1a. The cover 12 is rotatably connected to the shell 11 and can open or close the mounting port.

[0046] In one embodiment, please refer to Figure 4 A guide strip A is provided in one of the annular shell 2 and the cavity wall of the dissolving chamber 1a, and a guide groove is provided in one of the annular shell 2 and the cavity wall of the dissolving chamber 1a, and the guide strip A cooperates with the guide groove for guiding.

[0047] Exemplarily, the outer side of the ring shell 2 may be provided with a guide bar A, and the circumferential cavity wall of the dissolving cavity 1a may be provided with a guide groove, which extends in the up-down direction. By providing the guide bar A and the guide groove, the guide groove can provide a smooth and accurate moving path, and the guide bar A can slide easily in the guide groove, making the entire moving process more accurate and controllable; on the other hand, the guide groove can provide additional support and stability, avoiding the shaking or unstable sliding of the guide bar A during the moving process, and the moving is stable, and after the guide groove cooperates with the guide bar A, the circumferential rotation of the ring shell 2 under the fluid action of the dissolved liquid can be reduced.

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

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

[0050] For example, in one embodiment, please refer to Figure 4 and Figure 7 A limiting column A1 is provided at the lower end of the guide bar A. In the process of the guide bar A passing upward through the limiting groove 2b2, the limiting column A1 at the lower end of the guide bar A abuts against the bottom surface of the mounting ear 2b located at the lower end of the ring shell 2, and then the guide bar A and the ring shell 2 are inserted downward into the guide groove together.

[0051] For example, in one embodiment, please refer to Figure 4 A guide block A2 is provided at the lower end of the guide bar A. The size of the guide block A2 along the radial direction of the ring shell 2 gradually increases from bottom to top. In this way, when the guide bar A is inserted into the guide groove, the guide block A2 can serve as a guide.

[0052] For example, in one embodiment, please refer to Figure 4 A stopper A3 is provided at the upper end of the guide bar A. After the guide bar A is inserted into the guide groove, the stopper A3 can abut against the top surface of the limiting groove 2b2.

[0053] In one embodiment, please refer to Figure 1The dissolution device 100 includes a heating jacket 4, and the housing 1 is sleeved in the heating jacket 4. In this way, the dissolution chamber 1a can be heated along the circumferential direction. On the one hand, the kinetic energy of the molecules can be increased, 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 dissolution rate; on the other hand, the circumferential heating can provide a consistent heat source around the dissolution chamber 1a, which is conducive to uniform heating, thereby reducing the situation where the reaction is uneven due to local overheating.

[0054] Exemplarily, in one embodiment, the heating jacket 4 may be an electric heating jacket 4, and the temperature may be adjusted as needed.

[0055] In one embodiment, please refer to Figure 4 The dissolving device 100 comprises a heat preservation sleeve 5, and the heating sleeve 4 is sleeved in the heat preservation sleeve 5. In this way, the outer shell 1 can be kept warm, and the loss of heat can be reduced to ensure that the dissolving process is carried out quickly.

[0056] In one embodiment, please refer to Figure 1 and Figure 2 A handle 2c is provided on the ring shell 2. Thus, by providing the handle 2c, the operator can carry the handle 2c to put the ring shell 2 into the dissolving chamber 1a or take it out from the dissolving chamber 1a, which is convenient and efficient.

[0057] In one embodiment, please refer to Figure 2 The dissolution device 100 includes a pressure sensor 6, a pressure relief valve 7 and a controller. The controller is respectively connected to the pressure sensor 6 and the pressure relief valve 7 for communication. The pressure sensor 6 is used to obtain the pressure in the dissolution chamber 1a. The pressure relief valve 7 connects the dissolution chamber 1a with the outside world. The controller is configured to control the pressure relief valve 7 to open or close according to the pressure value of the pressure sensor 6.

[0058] Exemplarily, the pressure sensor 6 and the pressure relief valve 7 can both be arranged on the cover 12, and the pressure sensor 6 can obtain the pressure in the dissolution chamber 1a, and the pressure relief valve 7 connects the dissolution chamber 1a with the outside world. The controller can be a PLC system. The controller can be connected to 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 dissolution chamber 1a reaches the threshold pressure, the pressure sensor 6 will send a pressure overload signal to the controller. After receiving the signal, the controller controls the pressure relief valve 7 to open to relieve the pressure in the dissolution chamber 1a, thereby reducing dangerous accidents such as explosions caused by excessive pressure.

[0059] In one embodiment, please refer to Figure 2The dissolving device 100 includes an air supply valve 8, which connects the dissolving chamber 1a with the outside, and is connected to the control communication. In this way, when the pressure sensor 6 detects that the pressure in the dissolving chamber 1a is lower than the set pressure, the pressure sensor 6 will send a pressure shortage signal to the controller. After receiving the signal, the controller controls the air supply valve 8 to replenish gas to the dissolving chamber 1a, so that the pressure in the dissolving chamber 1a reaches the set pressure, so that the dissolving rate can be further accelerated.

[0060] For example, in one embodiment, please refer to Figure 1 and Figure 2 The dissolving device 100 includes a pressure gauge 9, which can be set on the cover 12 to detect the pressure in the dissolving chamber 1a. By cooperating with the pressure sensor 6, double insurance can be used to minimize the situation of excessive pressure and loss of control.

[0061] For example, in one embodiment, please refer to Figure 2 The dissolution device 100 includes a temperature sensor 10 for monitoring the temperature of the dissolution chamber 1a. The temperature sensor 10 and the heating jacket 4 can be connected to the controller for communication. In this way, when the temperature sensor 10 detects that the temperature in the dissolution chamber 1a is lower than the set temperature or higher than the set temperature, the temperature sensor 10 can send a signal to the controller. After receiving the signal, the controller can control the heating jacket 4 to regulate the temperature in the dissolution chamber 1a, with a high degree of automation.

[0062] In one embodiment, the dissolution device 100 includes a sampling tube, a first valve and a second valve. The sampling tube connects the dissolution chamber 1a with the outside. The first valve and the second valve are respectively arranged in the middle of the sampling tube and at one end close to the outside.

[0063] For example, see Figure 2 The housing 1 is formed with a sampling port connected to the dissolution chamber 1a, one end of the sampling tube is located in the dissolution chamber 1a, and the other end of the taking-in and putting-out tube passes through the sampling port and is connected to the outside world. The first valve can be set in the middle of the sampling tube, and the second valve can be set at one end of the taking-in and putting tube close to the sampling port. In this way, during sampling and testing, the first valve and the second valve can be opened, and the pressure of the dissolution chamber 1a will cause part of the dissolved liquid to flow into the sampling tube, and then the first valve is closed to separate the dissolved liquid in the sampling tube from the dissolution chamber 1a, and then the dissolved liquid in the sampling tube located between the first valve and the second valve is depressurized, cooled, and sampled. After the sampling is completed, the first valve is opened and the second valve is closed to return the dissolved liquid in the sampling tube to the dissolution chamber 1a. In this way, the two-stage sampling can be used to achieve sampling during the high-temperature and high-pressure dissolution reaction process, with high safety.

[0064] The above is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. All modifications, equivalent substitutions, improvements, etc. within the spirit and principles of the present application are included in the protection scope of the present application.

Claims

1. A dissolving device for dissolving spent fuel, characterized in that: include: The shell is formed with a dissolving cavity for containing the dissolving liquid; an annular shell, arranged in the dissolution chamber, the annular shell having an inner wall and an outer wall, an interlayer formed between the outer wall and the inner wall, the outer wall and the inner wall both forming openings communicating with the interlayer, the spent fuel being arranged in the interlayer; A stirring member is arranged in the dissolving chamber and is used for stirring the dissolving liquid.

2. The dissolving device according to claim 1, characterized in that: The stirring member is arranged in the annular shell.

3. The dissolving device according to claim 1, characterized in that: The stirring element is a magnetic stirrer.

4. The dissolving device according to claim 1, characterized in that: The annular shell is detachably arranged on the cavity wall of the dissolving cavity.

5. The dissolving device according to claim 4, characterized in that: One of the annular shell and the cavity wall of the dissolving chamber is provided with a guide strip, and one of the annular shell and the cavity wall of the dissolving chamber is provided with a guide groove, and the guide strip is in guiding cooperation with the guide groove.

6. The dissolving device according to claim 1, characterized in that: The dissolving device comprises a heating jacket, and the outer shell is sleeved in the heating jacket.

7. The dissolving device according to claim 6, characterized in that The dissolving device comprises a heat-insulating sleeve, and the heating sleeve is arranged in the heat-insulating sleeve.

8. The dissolving device according to claim 1, characterized in that: The dissolution device includes a pressure sensor, a pressure relief valve and a controller, wherein the controller is communicatively connected to the pressure sensor and the pressure relief valve respectively, the pressure sensor is used to obtain the pressure in the dissolution chamber, the pressure relief valve connects the dissolution chamber with the outside world, and the controller is configured to control the pressure relief valve to open or close according to the pressure value of the pressure sensor.

9. The dissolving device according to claim 1, characterized in that: The dissolving device comprises a sampling tube, a first valve and a second valve. The sampling tube connects the dissolving chamber and the outside world. The first valve and the second valve are respectively arranged at the middle part of the sampling tube and at one end close to the outside world.

10. The dissolving device according to claim 1, characterized in that: The spent fuel is a plutonium-uranium oxide mixed fuel.

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