A system and method for oxidizing treatment of radioactive waste resins in a molten salt bath

Abstract

The present application relates to a kind of system and method for oxidizing treatment of radioactive waste resin in molten salt bath, including pretreatment unit, feed unit, high-temperature reaction unit and discharge unit, the pretreatment unit is used to control the moisture content of radioactive waste resin to be treated below 15%, and the radioactive waste resin with moisture content below 15% is transported to high-temperature reaction unit;The feed unit is used to transport oxidizing gas, inert gas and carbonate to high-temperature reaction unit;The high-temperature reaction unit includes melting furnace, the melting furnace is used to oxidize the radioactive waste resin transported by feed unit in high-temperature molten salt bath, and the radioactive waste salt obtained after treatment;The discharge unit is used to receive the radioactive waste salt obtained after treatment in melting furnace.Compared with prior art, the present application has the advantages of high decomposition efficiency of radioactive waste resin, significant volume reduction effect, reduced entrainment of radioactive waste, better safety and the like.

Description

Technical Field

[0001] This invention relates to the field of radioactive waste resin treatment, and in particular to a system and method for oxidizing radioactive waste resin in a molten salt bath. Background Technology

[0002] Nuclear facilities generate a certain amount of radioactive waste resin during military production, decommissioning, and radioactive waste management. Radioactive waste resin is flammable, prone to leakage, and produces explosive gases after radiolysis or pyrolysis. Furthermore, long-term storage can lead to pulverization and caking, making retrieval difficult. Its temporary storage poses significant safety risks. Therefore, it is essential to conduct research on radioactive waste resin treatment technologies and their engineering applications.

[0003] For the treatment of radioactive waste resin, China has carried out research on technologies such as polymer curing, incineration, hot supercompression, temporary storage in highly integrated containers, wet oxidation, plasma oxidation, in-tank drying, and steam reforming. However, most of these studies are still at the laboratory research or pilot-scale stage, and no technology suitable for large-scale engineering application has yet been found.

[0004] Cement solidification is a commonly used method for treating radioactive waste resin, but this method has problems such as low encapsulation capacity, high nuclide leaching rate, and large volume expansion ratio. Therefore, it is essential to conduct research on radioactive waste resin treatment technology and its engineering applications. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of commonly used radioactive waste resin treatment methods, such as low capacity, high nuclide leaching rate, and large capacity expansion ratio, and to provide a system and method for oxidizing radioactive waste resin in a molten salt bath.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A system for oxidizing radioactive waste resin in a molten salt bath includes a pretreatment unit, a feeding unit, a high-temperature reaction unit, and a discharge unit.

[0008] The pretreatment unit is used to control the moisture content of the radioactive waste resin to be treated to below 15%, and to transfer the radioactive waste resin with a moisture content of below 15% to the high-temperature reaction unit.

[0009] The feeding unit is used to transfer oxidizing gas, inert gas and carbonate to the high-temperature reaction unit;

[0010] The high-temperature reaction unit includes a melting furnace, which is used to oxidize the radioactive waste resin transferred from the feeding unit in a high-temperature molten salt bath to obtain radioactive waste salt.

[0011] The discharge unit is used to receive radioactive waste salt obtained after processing in the melting furnace.

[0012] Furthermore, the pretreatment unit includes a drying box and a resin funnel connected by a pipe. The bottom of the resin funnel is equipped with a resin feeding vibrating feeder. The resin funnel is connected to the melting furnace through a resin feeding pipe, which leads to the bottom of the melting furnace.

[0013] The drying chamber is used to receive and dry the radioactive waste resin to be treated, and to calculate the moisture content of the radioactive waste resin to be treated by weighing.

[0014] The resin funnel is used to receive and temporarily store radioactive waste resin with a moisture content of less than 15%.

[0015] The resin feeding vibrating feeder is used to vibrate and spread the radioactive waste resin in the resin funnel, and the resin feeding vibrating feeder controls the resin funnel to transfer the radioactive waste resin to the melting furnace.

[0016] Furthermore, the radioactive waste resin to be treated includes gases, carbonates, and radioactive waste resin.

[0017] Furthermore, the top of the drying chamber is connected to the drying chamber condenser via a pipe, and the bottom of the drying chamber condenser is connected to the droplet collector via a pipe.

[0018] The lower end of the condenser of the drying chamber is connected to the cooling water inlet through a pipe, and the upper end of the condenser of the drying chamber is connected to the cooling water outlet through a pipe. A temperature measuring instrument is installed on the pipe.

[0019] The top of the droplet collector is connected to the outlet.

[0020] Furthermore, the feeding unit includes an inert gas inlet pipe and an oxidizing gas inlet pipe. The inert gas inlet pipe is sequentially equipped with an inert gas inlet, a first inert gas ball valve, an inert gas flow meter, and a second inert gas ball valve. The inert gas inlet pipe is connected to the resin feeding pipe, and the inert gas enters the resin feeding pipe through the inert gas inlet.

[0021] The oxidizing gas inlet pipe is sequentially equipped with an oxidizing gas inlet, a first oxidizing gas ball valve, an oxidizing gas flow meter, and a second oxidizing gas ball valve. The oxidizing gas inlet pipe is connected to the inert gas inlet pipe, and the oxidizing gas enters the inert gas inlet pipe through the oxidizing gas inlet.

[0022] Furthermore, the feeding unit also includes a carbonate feeding funnel, below which is a carbonate feeding vibrating feeder. The carbonate feeding funnel is connected to the melting furnace through a carbonate feeding pipe, which leads to the bottom of the melting furnace. The carbonate is fed into the bottom of the melting furnace by controlling the carbonate feeding funnel through the carbonate feeding vibrating feeder. The feeding of radioactive waste resin is achieved when the carbonate is in a high-temperature molten state.

[0023] Furthermore, a cooling water circulation pipe is provided on the outside of the resin feed pipe and the carbonate feed pipe. The cooling water circulation pipe is located on the outside of the top of the melting furnace. The lower end of the cooling water circulation pipe is connected to the cooling water inlet through a pipe, and the upper end of the cooling water circulation pipe is connected to the cooling water outlet through a pipe. A safety valve is provided on the pipe connecting the cooling water circulation pipe and the cooling water outlet. The cooling water circulation pipe is used to prevent hot steam in the melting furnace from flowing back into the resin feed pipe and the carbonate feed pipe.

[0024] Furthermore, the melting furnace is equipped with detachable heating modules on both sides for easy disassembly, maintenance and replacement. The melting furnace is equipped with a temperature measuring instrument and an insulation layer inside the melting furnace, the insulation layer being made of alumina ceramic fiber.

[0025] Furthermore, the melting furnace, resin feed pipe, carbonate feed pipe, inert gas inlet pipe, and oxidizing gas inlet pipe are all made of Inconel 625 alloy steel, which has the properties of high temperature resistance and strong corrosion resistance.

[0026] Furthermore, the discharge unit includes a freeze-thaw valve and a receiving bucket. The receiving bucket is connected to the melting furnace via a pipe. The pipe is equipped with a freeze-thaw valve, which includes an air inlet device, a heater, and an insulation layer. The air inlet device includes a third inert gas inlet and a third inert gas outlet. The lower end of the freeze-thaw valve is connected to the third inert gas inlet via a pipe, and the upper end of the freeze-thaw valve is connected to the third inert gas outlet via a pipe. The insulation layer is a cooling jacket for the freeze-thaw valve. The freeze-thaw valve is equipped with a temperature measuring instrument. The receiving bucket is used to receive the radioactive waste salt obtained after processing in the melting furnace, and the freeze-thaw valve is used to discharge the oxidized radioactive waste salt.

[0027] Furthermore, the heater of the freeze-thaw valve is designed to have a relatively large power, which facilitates rapid heating and melting of the solidified waste residue. The air inlet device facilitates rapid cooling of the discharge pipe and achieves blockage of the discharge pipe. The insulation layer is designed to be relatively thin, which facilitates faster heat dissipation during cooling.

[0028] Furthermore, the system also includes an exhaust gas purification unit for treating gaseous waste generated in the melting furnace.

[0029] Furthermore, the exhaust gas purification unit includes a filter, a heat exchanger, a condenser, a demister, a gas heater, a medium-efficiency filter, a high-efficiency filter, a vane pump, and an exhaust gas outlet, all connected in sequence via pipelines.

[0030] The filter is connected to the top of the melting furnace via a pipe. The pipe connecting the filter and the heat exchanger is equipped with a second check valve, a temperature measuring instrument, and a one-way valve in sequence. A branch is also led out between the filter and the second check valve and connected to the second inert gas inlet. The connected pipe is equipped with a first check valve. The second inert gas inlet is used for backflushing inert gas.

[0031] The lower ends of the heat exchanger and condenser are connected to the cooling water inlet via a pipe, and the upper ends of the heat exchanger and condenser are connected to the cooling water outlet via a pipe, on which a temperature measuring instrument is installed.

[0032] The top of the demister is connected to the cooling water inlet via a pipe. Both sides of the demister, the medium-efficiency filter, and the high-efficiency filter are connected to pressure gauges via pipes. The pressure gauges are used to measure the pressure difference between the inlet and outlet air in the demister, the medium-efficiency filter, or the high-efficiency filter, respectively.

[0033] Furthermore, the exhaust gas purification unit also includes a waste liquid tank, which is connected to the heat exchanger, condenser, demister, drying chamber condenser, and droplet collector via pipelines.

[0034] Furthermore, the system also includes a control unit, which is a remote control workstation. Operators can remotely operate, manage, and monitor the device through the control unit, enabling remote control of all data and displaying all process parameters.

[0035] Furthermore, the present invention also provides a method for oxidizing radioactive waste resin in a molten salt bath, using the above-described system for oxidizing radioactive waste resin in a molten salt bath, and the specific steps are as follows:

[0036] S1. The radioactive waste resin to be treated is dried in a drying oven until its moisture content is controlled below 15%, and then temporarily stored in a resin funnel.

[0037] S2. The carbonate is temporarily stored in the carbonate feed hopper and then transported to the bottom of the melting furnace through the carbonate feed pipe via the carbonate feed vibrating feeder.

[0038] S3. The melting furnace is heated to the temperature of the carbonate inside the melting furnace by a heating module and the reaction temperature is maintained for a period of time, so that the carbonate inside the melting furnace is a molten salt bath in a molten state.

[0039] S4. After maintaining the reaction temperature for a period of time, an inert gas is introduced. Under the protection of the inert gas, the radioactive waste resin with a moisture content of less than 15% temporarily stored in the resin funnel is transported to the molten salt bath through the resin feed pipe.

[0040] S5. Introduce oxidizing gas to carry out the oxidation reaction, and continue to introduce oxidizing gas during the oxidation process;

[0041] S6. When the radioactive waste resin in the melting furnace is completely oxidized to obtain radioactive waste salt, open the freeze-thaw valve heater and discharge the radioactive waste salt to the receiving bucket at the bottom of the melting furnace for temporary storage.

[0042] S7. The gaseous waste generated by the melting furnace is discharged after being treated by the exhaust gas purification unit.

[0043] Furthermore, in step S1, the exhaust gas generated during the drying process is condensed by the condenser of the drying chamber, and then discharged after entering the droplet collector through a pipeline.

[0044] Furthermore, in step S1, the drying chamber adopts a bell-shaped furnace design, the bottom of the bell-shaped furnace is opened by lifting, the furnace chamber is designed to be 200℃, and in order to ensure that the radioactive waste resin reaches a moisture content of ≤15% in the drying chamber, the height of a single layer of material in the drying chamber is ≤50mm.

[0045] Further, in step S2, the carbonate is composed of a ternary carbonate eutectic salt Li2CO3-Na2CO3-K2CO3, which is used to provide a good temperature and material exchange environment for the oxidation of radioactive waste resin.

[0046] Furthermore, in step S3, the reaction temperature is 800℃~850℃ and the time is 30min.

[0047] Further, in step S4, the inert gas is nitrogen, and the specific steps for introducing nitrogen are as follows: open the inert gas inlet, adjust the first inert gas ball valve, control the flow rate of nitrogen to 20-30 L / min through the inert gas flow meter, and then introduce nitrogen.

[0048] Further, in step S5, the oxidizing gas is air, and the specific steps for introducing air are as follows: open the oxidizing gas inlet, adjust the first oxidizing gas ball valve, control the air flow rate at 20-30 L / min through the oxidizing gas flow meter, and then introduce air.

[0049] Furthermore, in step S6, the complete oxidation time of the radioactive waste resin is 2 hours.

[0050] Further, in step S7, the specific steps of the exhaust gas purification unit are as follows: filtration by a filter, heat exchange by a heat exchanger, cooling by a condenser, demisting by a demister, and filtration again by an electric heater, a medium-efficiency filter, and a high-efficiency filter, before being discharged from the exhaust gas outlet at the end of the vane pump.

[0051] Compared with the prior art, the advantages of the present invention are as follows:

[0052] 1. Under nitrogen protection and air conditions, an apparatus and method for treating radioactive waste resin in a molten salt bath are provided, and the apparatus has a series of functions such as pretreatment, feeding, high-temperature oxidation and discharging of radioactive waste resin.

[0053] 2. Radioactive waste resin was oxidized in a high-temperature molten salt bath, and the decomposition efficiency of the waste resin was as high as 98%, with a significant volume reduction effect. The volume reduction ratio of anion exchange resin was as high as 10, the volume reduction ratio of cation exchange resin was greater than 6, and the volume reduction ratio of mixed resin was about 7.

[0054] 3. On the other hand, it reduces the entrainment of radioactive waste, and the retention effect of various radionuclides in radioactive waste resin in carbonates is as high as 90% or more;

[0055] 4. At the same time, the entire device uses molten salt bath oxidation treatment of radioactive waste resin, which is flameless and has good safety; after oxidation, the radioactive waste resin exists in a more stable state, which is convenient for subsequent treatment and disposal. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of the present invention;

[0057] Figure 2 This is a diagram showing the equipment layout of the present invention;

[0058] Figure 3 For the present invention Figure 1 A schematic diagram of the intermediate cross-sectional structure of the freeze-thaw valve in its sealed state;

[0059] Figure 4 For the present invention Figure 1 A schematic diagram of the intermediate cross-sectional structure of the freeze-thaw valve in the open state;

[0060] Figure 5 This is a top view of the junction between the resin feed pipe and the cooling water circulation pipe in this invention.

[0061] Figure 6 This is a front view of the junction between the resin feed pipe and the cooling water circulation pipe in this invention.

[0062] Explanation of reference numerals in the attached figures: A, Pretreatment unit; 1, Drying oven; 2, Resin funnel; 7, Resin feed vibrating feeder; 19, Drying oven condenser; 20, Droplet collector.

[0063] B. Feeding unit; 3. Air; 4. Nitrogen; 5. Carbonate feed hopper; 6. Carbonate feed vibrating feeder; a. First oxidizing gas ball valve; b. First inert gas ball valve; c. Second oxidizing gas ball valve; d. Second inert gas ball valve; e. Shut-off valve; j. Oxidizing gas flow meter; k. Inert gas flow meter.

[0064] C. High-temperature reaction unit; 8. Melting furnace; m. Heating module; n. Cooling water circulation pipeline; f. Safety valve.

[0065] D. Discharge unit; 9. Freeze-thaw valve; 10. Receiving bucket; 11. Freeze-thaw valve cooling jacket.

[0066] E. Exhaust gas purification unit; 11. Filter; 12. Heat exchanger; 13. Condenser; 14. Demister; 15. Gas heater; 16. Medium efficiency filter; 17. High efficiency filter; 18. Vane pump; 21. Waste liquid tank; g. First check valve; h. Second check valve; i. One-way valve.

[0067] F. Control unit. Detailed Implementation

[0068] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0069] Example

[0070] See Figures 1 to 6 This embodiment provides a system for oxidizing radioactive waste resin in a molten salt bath, including a pretreatment unit A, a feeding unit B, a high-temperature reaction unit C, and a discharge unit D.

[0071] The pretreatment unit A is used to control the moisture content of the radioactive waste resin to be treated to below 15%, and to transfer the radioactive waste resin with a moisture content of below 15% to the high-temperature reaction unit C.

[0072] The feeding unit B is used to transfer oxidizing gas, inert gas and carbonate to the high-temperature reaction unit C;

[0073] The high-temperature reaction unit C includes a melting furnace 8, which is used to oxidize the radioactive waste resin transferred from the feeding unit B in a high-temperature molten salt bath to obtain radioactive waste salt.

[0074] The discharge unit D is used to receive the radioactive waste salt obtained after processing in the melting furnace 8.

[0075] In this embodiment, the pretreatment unit A includes a drying box 1 and a resin funnel 2 connected by a pipe. The bottom end of the resin funnel 2 is provided with a resin feeding vibrating feeder 7. The resin funnel 2 is connected to a melting furnace 8 through a resin feeding pipe, and the resin feeding pipe leads into the bottom of the melting furnace 8.

[0076] The drying chamber 1 is used to receive and dry the radioactive waste resin to be treated, and to calculate the moisture content of the radioactive waste resin to be treated by weighing.

[0077] The resin funnel 2 is used to receive and temporarily store radioactive waste resin with a moisture content of less than 15%.

[0078] The resin feeding vibrating feeder 7 is used to vibrate and spread the radioactive waste resin in the resin funnel 2, and the resin feeding vibrating feeder 7 controls the resin funnel 2 to transfer the radioactive waste resin to the melting furnace 8.

[0079] In this embodiment, the radioactive waste resin to be treated includes gas, carbonates, and radioactive waste resin.

[0080] In this embodiment, the top of the drying chamber 1 is connected to the drying chamber condenser 19 via a pipe, and the bottom of the drying chamber condenser 19 is connected to the droplet collector 20 via a pipe.

[0081] The lower end of the condenser 19 of the drying chamber is connected to the cooling water inlet through a pipe, and the upper end of the condenser 19 of the drying chamber is connected to the cooling water outlet through a pipe. A temperature measuring instrument is installed on the pipe.

[0082] The droplet collector 20 is connected to the outlet at its top.

[0083] In this embodiment, the feeding unit B includes an inert gas inlet pipe and an oxidizing gas inlet pipe. The inert gas inlet pipe is sequentially provided with an inert gas inlet, a first inert gas ball valve b, an inert gas flow meter k, and a second inert gas ball valve d. The inert gas inlet pipe is connected to the resin feeding pipe, and the inert gas enters the resin feeding pipe through the inert gas inlet.

[0084] The oxidizing gas inlet pipe is sequentially equipped with an oxidizing gas inlet, a first oxidizing gas ball valve a, an oxidizing gas flow meter j, and a second oxidizing gas ball valve c. The oxidizing gas inlet pipe is connected to the inert gas inlet pipe, and the oxidizing gas enters the inert gas inlet pipe through the oxidizing gas inlet.

[0085] In this embodiment, the feeding unit B further includes a carbonate feeding funnel 5, and a carbonate feeding vibrating feeder 6 is provided below the carbonate feeding funnel 5. The carbonate feeding funnel 5 is connected to the melting furnace 8 through a carbonate feeding pipe, which leads to the bottom of the melting furnace 8. The carbonate is fed into the bottom of the melting furnace 8 by controlling the carbonate feeding funnel 5 through the carbonate feeding vibrating feeder 6. The feeding of radioactive waste resin is achieved when the carbonate is in a high-temperature molten state.

[0086] In this embodiment, a cooling water circulation pipe n is provided on the outside of the resin feed pipe and the carbonate feed pipe. The cooling water circulation pipe n is located on the outside of the top of the melting furnace 8. The lower end of the cooling water circulation pipe n is connected to the cooling water inlet through a pipe, and the upper end of the cooling water circulation pipe n is connected to the cooling water outlet through a pipe. A safety valve f is provided on the pipe connecting the cooling water circulation pipe n and the cooling water outlet. The cooling water circulation pipe n is used to prevent hot steam in the melting furnace 8 from flowing back into the resin feed pipe and the carbonate feed pipe.

[0087] In this embodiment, the melting furnace 8 is provided with detachable heating modules m on both sides, which are convenient for disassembly, maintenance and replacement. The melting furnace 8 is provided with a temperature measuring instrument and a heat insulation layer is provided inside the melting furnace 8. The heat insulation layer is made of alumina ceramic fiber.

[0088] In this embodiment, the melting furnace 8, resin feed pipe, carbonate feed pipe, inert gas inlet pipe, and oxidizing gas inlet pipe are all made of Inconel 625 alloy steel, which has the properties of high temperature resistance and strong corrosion resistance.

[0089] In this embodiment, the discharge unit D includes a freeze-thaw valve 9 and a receiving tank 10. The receiving tank 10 is connected to the melting furnace 8 via a pipe. The freeze-thaw valve 9 is installed on the pipe. The freeze-thaw valve 9 includes an air inlet device, a heater, and an insulation layer. The air inlet device includes a third inert gas inlet and a third inert gas outlet. The lower end of the freeze-thaw valve 9 is connected to the third inert gas inlet via a pipe, and the upper end of the freeze-thaw valve 9 is connected to the third inert gas outlet via a pipe. The insulation layer is a freeze-thaw valve cooling jacket 1. The freeze-thaw valve 9 is equipped with a temperature measuring instrument. The receiving tank 10 is used to receive the radioactive waste salt obtained after processing in the melting furnace 8, and the freeze-thaw valve 9 is used to discharge the oxidized radioactive waste salt.

[0090] In this embodiment, the heater power of the freeze-thaw valve 9 is designed to be relatively large, which facilitates rapid heating and melting of the solidified waste residue. The air inlet device facilitates rapid cooling of the discharge pipe and achieves blockage of the discharge pipe. The thickness of the insulation layer is set to be relatively thin, which facilitates faster heat dissipation during cooling.

[0091] In this embodiment, the system further includes an exhaust gas purification unit E, which is used to treat gaseous waste generated in the melting furnace 8.

[0092] In this embodiment, the exhaust gas purification unit E includes a filter 11, a heat exchanger 12, a condenser 13, a demister 14, a gas heater 15, a medium-efficiency filter 16, a high-efficiency filter 17, a vane pump 18, and an exhaust gas outlet, all connected in sequence via pipes.

[0093] The filter 11 is connected to the top of the melting furnace 8 via a pipe. The pipe connecting the filter 11 and the heat exchanger 12 is equipped with a second check valve h, a temperature measuring instrument and a one-way valve i in sequence. A branch is also led out between the filter 11 and the second check valve h to connect to the second inert gas inlet. The connected pipe is equipped with a first check valve g. The second inert gas inlet is used for backflushing inert gas 4.

[0094] The lower ends of the heat exchanger 12 and the condenser 13 are connected to the cooling water inlet through a pipe, and the upper ends of the heat exchanger 12 and the condenser 13 are connected to the cooling water outlet through a pipe. A temperature measuring instrument is installed on the pipe.

[0095] The top of the demister 14 is connected to the cooling water inlet via a pipe. Both sides of the demister 14, the medium-efficiency filter 16, and the high-efficiency filter 17 are connected to pressure gauges via pipes. The pressure gauges are used to measure the pressure difference between the inlet and outlet air in the demister 14, the medium-efficiency filter 16, or the high-efficiency filter 17, respectively.

[0096] In this embodiment, the exhaust gas purification unit E further includes a waste liquid tank 21, which is connected to the heat exchanger 12, condenser 13, demister 14, drying chamber condenser 19 and droplet collector 20 via pipes.

[0097] In this embodiment, the system also includes a control unit F, which is a remote control workstation. Operators can remotely operate, manage, and monitor the device through the control unit F, enabling remote control of all data and displaying all process parameters.

[0098] Furthermore, the present invention also provides a method for oxidizing radioactive waste resin in a molten salt bath, using the above-described system for oxidizing radioactive waste resin in a molten salt bath, and the specific steps are as follows:

[0099] S1. The radioactive waste resin to be treated is dried in the drying oven 1 to control its moisture content to below 15%, and then temporarily stored in the resin funnel 2. The tail gas generated during the drying process is condensed by the drying oven condenser 19 and discharged through the pipe into the droplet collector 20.

[0100] S2, the ternary carbonate eutectic salt Li2CO3-Na2CO3-K2CO3 is temporarily stored in the carbonate feed hopper 5 and then transported to the bottom of the melting furnace 8 through the carbonate feed pipe via the carbonate feed vibrating feeder 6.

[0101] S3. The melting furnace 8 is heated by the heating module m to maintain the temperature of the carbonate inside the melting furnace 8 at 800℃~850℃ for 30 minutes, so that the carbonate inside the melting furnace 8 is a molten salt bath in a molten state.

[0102] S4. After maintaining the reaction temperature for a period of time, open the inert gas inlet. The inert gas is nitrogen. Adjust the first inert gas ball valve b and control the flow rate of nitrogen 4 to 20-30 L / min through the inert gas flow meter k. Then, introduce nitrogen 4. Under the protection of nitrogen 4, the radioactive waste resin with a moisture content of less than 15% temporarily stored in the resin funnel 2 is transported to the molten salt bath in a molten state through the resin feed pipe.

[0103] S5. Open the oxidizing gas inlet. The oxidizing gas is air. Adjust the first oxidizing gas ball valve a. After controlling the flow rate of air 3 to 20-30 L / min through the oxidizing gas flow meter j, introduce air 3 to carry out the oxidation reaction. Continue to introduce air 3 during the oxidation process.

[0104] S6. After the radioactive waste resin in the melting furnace 8 is completely oxidized for 2 hours, radioactive waste salt is obtained. The freeze-thaw valve 9 heater is turned on, and the radioactive waste salt is discharged to the receiving bucket 10 at the bottom of the melting furnace 8 for temporary storage.

[0105] S7. The gaseous waste generated by the melting furnace 8 is filtered by filter 11 in the tail gas purification unit E, heat exchanged by heat exchanger 12, cooled by condenser 13, demisted by demister 14, and filtered again by electric heater 15, medium-efficiency filter 16 and high-efficiency filter 17 before being discharged from the tail gas outlet at the end of vane pump 18.

[0106] In this embodiment, in step S1, the drying chamber 1 adopts a bell-shaped furnace design. The bottom of the bell-shaped furnace is opened by lifting. The furnace chamber of the bell-shaped furnace is designed to have a temperature of 200°C. In order to ensure that the radioactive waste resin reaches a moisture content of ≤15% in the drying chamber, the height of a single layer of material in the drying chamber 1 is ≤50mm.

[0107] In this embodiment, in step S2, the ternary carbonate eutectic salt Li2CO3-Na2CO3-K2CO3 is used to provide a good temperature and material exchange environment for the oxidation of radioactive waste resin.

[0108] Under nitrogen protection and air conditions, this embodiment provides an apparatus and method for treating radioactive waste resin in a molten salt bath, and the apparatus has a series of functions such as pretreatment, feeding, high-temperature oxidation and discharging of radioactive waste resin.

[0109] Oxidation treatment of radioactive waste resin in a high-temperature molten salt bath achieves a decomposition efficiency of up to 98% and significant volume reduction. The volume reduction ratio is as high as 10 for anion exchange resin, greater than 6 for cation exchange resin, and approximately 7 for mixed resin. Furthermore, it reduces the entrainment of radioactive waste, with over 90% retention of various radionuclides in the carbonate within the waste resin. The entire device utilizes molten salt bath oxidation, eliminating flames and ensuring good safety. Oxidation also results in a more stable state for the radioactive waste resin, facilitating subsequent treatment and disposal.

[0110] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A system for oxidizing radioactive waste resin in a molten salt bath, characterized in that, It includes a pretreatment unit (A), a feeding unit (B), a high-temperature reaction unit (C), and a discharge unit (D). The pretreatment unit (A) is used to control the moisture content of the radioactive waste resin to be treated to below 15%, and to transfer the radioactive waste resin with a moisture content of below 15% to the high-temperature reaction unit (C). The feeding unit (B) is used to transfer oxidizing gas, inert gas and carbonate to the high-temperature reaction unit (C). The high-temperature reaction unit (C) includes a melting furnace (8), which is used to oxidize the radioactive waste resin transferred from the feeding unit (B) in a high-temperature molten salt bath to obtain radioactive waste salt. The discharge unit (D) is used to receive the radioactive waste salt obtained after processing in the melting furnace (8); The pretreatment unit (A) includes a drying chamber (1) for receiving and drying the radioactive waste resin to be treated. The radioactive waste resin to be treated includes gases, carbonates, and radioactive waste resin. The moisture content of the radioactive waste resin to be treated is calculated by weighing. The top of the drying chamber (1) is connected to the drying chamber condenser (19) through a pipe, and the bottom of the drying chamber condenser (19) is connected to the droplet collector (20) through a pipe. The feeding unit (B) also includes a carbonate feeding funnel (5), and a carbonate feeding vibrating feeder (6) is provided below the carbonate feeding funnel (5). The carbonate feeding funnel (5) is connected to the melting furnace (8) through a carbonate feeding pipe. The carbonate feeding pipe leads to the bottom of the melting furnace (8). The carbonate is controlled by the carbonate feeding vibrating feeder (6) to enter the bottom of the melting furnace (8). The feeding of radioactive waste resin is achieved in the state of high temperature melting of carbonate. A cooling water circulation pipe (n) is provided on the outside of the resin feed pipe and the carbonate feed pipe. The cooling water circulation pipe (n) is located on the outside of the top of the melting furnace (8). The lower end of the cooling water circulation pipe (n) is connected to the cooling water inlet through a pipe, and the upper end of the cooling water circulation pipe (n) is connected to the cooling water outlet through a pipe. A safety valve (f) is provided on the pipe connecting the cooling water circulation pipe (n) to the cooling water outlet. The cooling water circulation pipe (n) is used to prevent hot steam in the melting furnace (8) from flowing back into the resin feed pipe and the carbonate feed pipe. The discharge unit (D) includes a freeze-thaw valve (9) and a receiving bucket (10). The receiving bucket (10) is connected to the melting furnace (8) through a pipe. The pipe is equipped with a freeze-thaw valve (9). The receiving bucket (10) is used to receive the radioactive waste salt obtained after processing in the melting furnace (8). The freeze-thaw valve (9) is used to discharge the oxidized radioactive waste salt. The freeze-thaw valve (9) includes an air inlet device, a heater, and an insulation layer. The air inlet device includes a third inert gas inlet and a third inert gas outlet. The lower end of the freeze-thaw valve (9) is connected to the third inert gas inlet through a pipe, and the upper end of the freeze-thaw valve (9) is connected to the third inert gas outlet through a pipe. The insulation layer is a freeze-thaw valve cooling jacket (l). The freeze-thaw valve (9) is equipped with a temperature measuring instrument. The system also includes an exhaust gas purification unit (E), which includes a filter (11), a heat exchanger (12), a condenser (13), a demister (14), a gas heater (15), a medium-efficiency filter (16), a high-efficiency filter (17), a vane pump (18), and an exhaust gas outlet, all connected in sequence by pipes; the exhaust gas purification unit (E) also includes a waste liquid tank (21), which is connected to the heat exchanger (12), the condenser (13), the demister (14), the drying chamber condenser (19), and the droplet collector (20) by pipes.

2. The system for oxidizing radioactive waste resin in a molten salt bath according to claim 1, characterized in that, The pretreatment unit (A) also includes a resin funnel (2), which is connected to the drying box (1) by a pipe. The bottom of the resin funnel (2) is provided with a resin feeding vibrating feeder (7). The resin funnel (2) is connected to the melting furnace (8) by a resin feeding pipe, which leads to the bottom of the melting furnace (8). The resin funnel (2) is used to receive and temporarily store radioactive waste resin with a moisture content of less than 15%. The resin feeding vibrating feeder (7) is used to vibrate and spread the radioactive waste resin in the resin funnel (2), and the resin feeding vibrating feeder (7) transfers the radioactive waste resin to the melting furnace (8) by controlling the resin funnel (2).

3. The system for oxidizing radioactive waste resin in a molten salt bath according to claim 2, characterized in that, The lower end of the condenser (19) of the drying chamber is connected to the cooling water inlet via a pipe, and the upper end of the condenser (19) of the drying chamber is connected to the cooling water outlet via a pipe. A temperature measuring instrument is installed on the pipe. The droplet trap (20) is connected to the outlet at its top.

4. A system for oxidizing radioactive waste resin in a molten salt bath according to claim 2, characterized in that, The feeding unit (B) includes an inert gas inlet pipe and an oxidizing gas inlet pipe. The inert gas inlet pipe is sequentially equipped with an inert gas inlet, a first inert gas ball valve (b), an inert gas flow meter (k), and a second inert gas ball valve (d). The inert gas inlet pipe is connected to the resin feeding pipe, and the inert gas enters the resin feeding pipe through the inert gas inlet. The oxidizing gas inlet pipe is provided with an oxidizing gas inlet, a first oxidizing gas ball valve (a), an oxidizing gas flow meter (j), and a second oxidizing gas ball valve (c) in sequence. The oxidizing gas inlet pipe is connected to the inert gas inlet pipe, and the oxidizing gas enters the inert gas inlet pipe through the oxidizing gas inlet.

5. A system for oxidizing radioactive waste resin in a molten salt bath according to claim 1, characterized in that, The melting furnace (8) is provided with detachable heating modules (m) on both sides, which are convenient for disassembly, maintenance and replacement. The melting furnace (8) is provided with a temperature measuring instrument. The melting furnace (8) is provided with a heat insulation layer. The heat insulation layer is made of alumina ceramic fiber. The melting furnace (8), resin feed pipe, carbonate feed pipe, inert gas inlet pipe and oxidizing gas inlet pipe are all made of Inconel 625 alloy steel, which has the properties of high temperature resistance and strong corrosion resistance.

6. A system for oxidizing radioactive waste resin in a molten salt bath according to claim 1, characterized in that, The filter (11) is connected to the top of the melting furnace (8) via a pipe. The pipe connecting the filter (11) and the heat exchanger (12) is provided with a second check valve (h), a temperature measuring instrument and a one-way valve (i) in sequence. A branch is also led out between the filter (11) and the second check valve (h) and connected to the second inert gas inlet. The pipe is provided with a first check valve (g). The second inert gas inlet is used for backflushing inert gas (4). The lower ends of the heat exchanger (12) and condenser (13) are connected to the cooling water inlet through a pipe, and the upper ends of the heat exchanger (12) and condenser (13) are connected to the cooling water outlet through a pipe. A temperature measuring instrument is provided on the pipe. The top of the demister (14) is connected to the cooling water inlet through a pipe. Both sides of the demister (14), the medium-efficiency filter (16), and the high-efficiency filter (17) are connected to pressure gauges through pipes. The pressure gauges are used to measure the pressure difference between the inlet and outlet air in the demister (14), the medium-efficiency filter (16), or the high-efficiency filter (17), respectively.

7. A method for oxidizing radioactive waste resin in a molten salt bath, comprising the system for oxidizing radioactive waste resin in a molten salt bath as described in claim 6, wherein the specific steps are as follows: S1. The radioactive waste resin to be treated is dried in a drying oven (1) until its moisture content is controlled below 15%, and then temporarily stored in a resin funnel (2). S2. The carbonate is temporarily stored in the carbonate feed hopper (5) and transported to the bottom of the melting furnace (8) through the carbonate feed vibrating feeder (6) and carbonate feed pipe. S3. The melting furnace (8) is heated to the temperature of the carbonate inside the melting furnace (8) by the heating module (m) and the reaction temperature is maintained for a period of time so that the carbonate inside the melting furnace (8) is a molten salt bath in a molten state; S4. After maintaining the reaction temperature for a period of time, an inert gas is introduced. Under the protection of the inert gas, the radioactive waste resin with a moisture content of less than 15% temporarily stored in the resin funnel (2) is transported to the molten salt bath through the resin feed pipe. S5. Introduce oxidizing gas to carry out the oxidation reaction, and continue to introduce oxidizing gas during the oxidation process; S6. When the radioactive waste resin in the melting furnace (8) is completely oxidized to obtain radioactive waste salt, the freeze-thaw valve (9) heater is turned on and the radioactive waste salt is discharged to the receiving bucket (10) at the bottom of the melting furnace (8) for temporary storage. S7. The gaseous waste generated by the melting furnace (8) is discharged after being treated by the tail gas purification unit (E).

8. A method for oxidizing radioactive waste resin in a molten salt bath according to claim 7, characterized in that, In step S1, the exhaust gas generated during the drying process is condensed by the condenser (19) of the drying chamber, enters the droplet collector (20) through a pipeline, and is then discharged. In step S1, the drying box (1) adopts a bell-shaped furnace design. The bottom of the bell-shaped furnace is opened by lifting. The furnace chamber of the bell-shaped furnace is designed to be 200℃. In order to make the radioactive waste resin reach a moisture content of ≤15% in the drying box, the height of a single layer of material in the drying box (1) is ≤50mm. In step S2, the carbonate is composed of a ternary carbonate eutectic salt Li2CO3-Na2CO3-K2CO3, which is used to provide a good temperature and material exchange environment for the oxidation of radioactive waste resin. In step S3, the reaction temperature is 800℃~850℃ and the time is 30min; In step S4, the inert gas is nitrogen (4). The specific steps for introducing the inert gas nitrogen (4) are as follows: open the inert gas inlet, adjust the first inert gas ball valve (b), and control the flow rate of nitrogen (4) at 20~30L / min through the inert gas flow meter (k) before introducing nitrogen (4). In step S5, the oxidizing gas is air (3). The specific steps for introducing the oxidizing gas air (3) are as follows: open the oxidizing gas inlet, adjust the first oxidizing gas ball valve (a), control the flow rate of air (3) to 20~30L / min through the oxidizing gas flow meter (j), and then introduce air (3). In step S6, the complete oxidation time of the radioactive waste resin is 2 hours. In step S7, the specific steps of the exhaust gas purification unit (E) are as follows: filter (11) filters, heat exchanger (12) exchanges heat, condenser (13) cools, demister (14) demistes, electric heater (15), medium-efficiency filter (16) and high-efficiency filter (17) filter again, and then the exhaust gas is discharged from the end exhaust gas outlet of the vane pump (18).

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