Separation, purification and recovery system and method for iodine-125 production

Abstract

The invention discloses a separation, purification and recovery system and method for iodine-125 production, and belongs to the technical field of freezing separation. The adsorption device is arranged on the downstream side of the irradiation device along the flow path direction, is communicated with the irradiation device and is used for performing primary iodine removal on the initial mixed gas output by the irradiation device; one end of the circulating pipeline is communicated with a downstream outlet of the adsorption device, and the other end of the circulating pipeline is communicated with a reflux inlet of the irradiation device; the first control valve is connected in parallel with the iodine removal tank, gas in the pipeline is frozen and recovered by virtue of negative pressure difference, and the temperature is raised to a first preset temperature, so that xenon 124 and xenon 125 are sublimated into mixed gas, and secondary iodine removal is realized; the second control valve is connected in parallel with a decay tank, the xenon mixed gas subjected to secondary iodine removal is frozen and recovered, xenon 125 is decayed into iodine-125, and then the temperature is increased to a first preset temperature to sublimate xenon-124; and the third control valve is connected in parallel with the gas storage tank, an inlet sucking pump of the gas storage tank pumps and stores the xenon-124 heated in the decay tank, and an outlet exhaust pump sends the xenon-124 back to the irradiation device.

Description

Technical Field

[0001] This application relates to the field of cryogenic separation technology, and in particular to a separation, purification and recovery system and method for iodine-125 production. Background Technology

[0002] Iodine-125 is an important medical radionuclide with a long half-life and moderate radiation energy, resulting in minimal radiation damage to human tissues. Therefore, it is widely used in biomedical research, radioimmunoassay, and brachytherapy for tumors.

[0003] Currently, the mainstream industrial method for preparing iodine-125 is reactor irradiation, with the core idea as follows: Xenon-124 is fed into the active zone of the reactor and irradiated with neutrons to generate xenon-125; then the xenon-125 is transferred to a decay tank, where it is converted into iodine-125 and recovered using its decay properties; finally, the recovered iodine-125 is extracted to the production line and prepared into an iodine-125 product solution through a leaching process.

[0004] However, the existing irradiation preparation process faces three major technical challenges: first, it is difficult to effectively separate iodine-126 impurities from the product; second, the recovery effect of the intermediate product xenon-125 is poor; and third, the recovery and reuse rate of the raw material xenon-124 is low. Among these, the separation effect of iodine-126 impurities and the recovery efficiency of xenon-125 directly affect the quality of the iodine-125 product; while the recovery and reuse rate of xenon-124 determines the cost of raw materials, thus affecting the economics of the entire preparation process.

[0005] In summary, the existing iodine-125 irradiation preparation process has shortcomings in impurity separation, intermediate product recovery, and raw material reuse, making it difficult to balance the quality of iodine-125 products with the preparation cost, and urgently needs optimization and improvement. Summary of the Invention

[0006] In view of this, this application provides a separation, purification and recovery system and method for iodine-125 production. The main purpose is to efficiently separate iodine-126 impurities to improve the quality of iodine-125 products, optimize the xenon-125 recovery process to ensure the production efficiency of iodine-125, and realize the recycling of xenon-124, thereby reducing raw material costs and improving process economy.

[0007] According to one aspect of this application, a separation, purification, and recovery system for iodine-125 production is provided, comprising: An irradiation device used to irradiate the feed gas with neutrons to generate an initial mixture; An adsorption device is disposed downstream of the irradiation device along the flow path and connected to the irradiation device, and is used to perform primary iodine removal treatment on the initial mixed gas output by the irradiation device. A circulation pipeline is provided, with one end connected to the downstream outlet of the adsorption device and the other end connected to the return inlet of the irradiation device; at least one first control valve, at least one second control valve and at least one third control valve are sequentially provided along the flow path of the circulation pipeline. The first control valve is connected in parallel with an iodine removal tank. The iodine removal tank is used to freeze and recover the gas in the circulation pipeline through negative pressure difference, and heat it to a first preset temperature so that xenon-124 and xenon-125 sublimate into gas to form a xenon gas mixture, thereby achieving two-stage iodine removal. The second control valve is connected in parallel with a decay tank. The decay tank is used to recover the xenon gas mixture obtained after two-stage iodine removal by freezing through negative pressure difference, so that xenon-125 decays into iodine-125 and is heated to the first preset temperature so that xenon-124 sublimates into gas. The third control valve is connected in parallel to a gas storage tank. A vacuum pump is installed on the inlet pipe of the gas storage tank. The vacuum pump is used to pump the xenon-124 formed in the decay tank after heating into the gas storage tank for storage. An exhaust pump is installed on the outlet pipe of the gas storage tank. The exhaust pump is used to return the xenon-124 stored in the gas storage tank to the irradiation device for reprocessing as needed.

[0008] Optionally, a circulation pump is also provided on the circulation pipeline. The circulation pump is located upstream of the first control valve near the adsorption device along the flow direction of the circulation pipeline, and is used to provide power for the flow of gas in the circulation pipeline.

[0009] Optionally, the circulation pipeline is further provided with at least one fourth control valve, which is located in the pipeline section between the second control valve and the third control valve; The fourth control valve is connected in parallel to a recovery tank, which is configured such that when the pump on the gas storage tank inlet pipeline is unable to completely pump the remaining xenon-124 in the decay tank and the circulation pipeline into the gas storage tank, the remaining xenon-124 in the decay tank and the circulation pipeline is recovered by connecting to the circulation pipeline using a negative pressure differential freezing method.

[0010] Optionally, a first pressure sensor is connected to the iodine removal tank, a second pressure sensor is connected to the decay tank, and a third pressure sensor is connected to the recovery tank.

[0011] Optionally, the separation, purification, and recovery system for iodine-125 production further includes: A refrigeration device for temperature control of the iodine removal tank, the decay tank, and the recovery tank; the refrigeration device is provided with temperature control chambers corresponding one-to-one with the iodine removal tank, the decay tank, and the recovery tank, each temperature control chamber is used to accommodate the corresponding iodine removal tank, the decay tank, or the recovery tank, and each temperature control chamber has an independent heating control module and a cooling control module.

[0012] Optionally, a fifth control valve and a first isolation valve are sequentially provided on the inlet pipe of the iodine removal tank, wherein the first isolation valve is located downstream of the fifth control valve; a second isolation valve and a sixth control valve are sequentially provided on the outlet pipe of the iodine removal tank, wherein the second isolation valve is located upstream of the sixth control valve; The decay tank has a seventh control valve and a third isolation valve installed sequentially on its inlet pipe, wherein the third isolation valve is located downstream of the seventh control valve; the decay tank has a fourth isolation valve and an eighth control valve installed sequentially on its outlet pipe, wherein the fourth isolation valve is located upstream of the eighth control valve. The gas storage tank is equipped with a ninth control valve on its inlet pipe, which is located downstream of the gas pump; the gas storage tank is equipped with a tenth control valve on its outlet pipe, which is located upstream of the exhaust pump. The inlet pipe of the recovery tank is provided with an eleventh control valve and a fifth isolation valve in sequence, wherein the fifth isolation valve is located downstream of the eleventh control valve; the outlet pipe of the recovery tank is provided with a sixth isolation valve and a twelfth control valve in sequence, wherein the sixth isolation valve is located upstream of the twelfth control valve.

[0013] According to another aspect of this application, a separation, purification, and recovery method for iodine-125 production is provided, applied to the separation, purification, and recovery system for iodine-125 production described in any one of the above claims, the method comprising: The raw material gas is irradiated with neutrons by the irradiation device to generate the initial mixed gas, wherein the initial mixed gas includes at least iodine-125, iodine-126, xenon-124 and xenon-125. The adsorption device is connected to the irradiation device, so that the initial mixed gas enters the adsorption device. The adsorption device adsorbs and retains iodine-125 and iodine-126 in the initial mixed gas, thus completing the first-stage iodine removal treatment. One end of the circulation pipeline is connected to the downstream outlet of the adsorption device, and the other end is connected to the return inlet of the irradiation device to form a circulation loop. At the same time, the first control valve, the second control valve and the third control valve on the circulation pipeline are closed, and the iodine removal tank is connected to the circulation pipeline. The iodine removal tank is cooled down, and the gas that has undergone primary iodine removal in the circulation pipeline is pumped into the iodine removal tank using the negative pressure difference inside the iodine removal tank. The gas is condensed through freezing. After the gas is recovered, the connection between the inlet pipeline of the iodine removal tank and the circulation pipeline is cut off, and the iodine removal tank is heated up to the first preset temperature. The condensed xenon-124 and xenon-125 sublimate to form the xenon gas mixture, while the residual iodine-125 and iodine-126 remain in the iodine removal tank, thus completing the secondary iodine removal. The decay tank is cooled down while maintaining its connection with the iodine removal tank. The negative pressure difference inside the decay tank is used to draw the xenon gas mixture formed in the iodine removal tank into the decay tank. The xenon gas mixture is condensed through freezing. After the xenon gas mixture is recovered, the connection between the decay tank and the iodine removal tank is cut off, allowing the xenon gas mixture to stand in the decay tank for xenon-125 to decay into iodine-125. After the decay is complete, the temperature inside the decay tank is raised to the first preset temperature, causing xenon-124 to sublimate and form xenon gas. The gas storage tank is connected to the decay tank, and the vacuum pump is started to pump the sublimated xenon-124 in the decay tank into the gas storage tank. After the xenon-124 is pumped out, the vacuum pump is turned off and the connection between the gas storage tank and the decay tank is cut off, thus completing the recovery and storage of xenon-124. Subsequently, according to production needs, the gas storage tank can be connected to the irradiation device, and the xenon-124 stored in the gas storage tank can be returned to the irradiation device for reprocessing through the exhaust pump.

[0014] Optionally, if a fourth control valve is further provided on the circulation pipeline, and the fourth control valve is connected in parallel with a recovery tank, the method further includes: When the pump cannot completely pump the remaining xenon-124 from the decay tank and the circulation pipeline to the storage tank, the connection between the storage tank and the decay tank is cut off. At the same time, the recovery tank is cooled down and connected to the circulation pipeline. The negative pressure difference inside the recovery tank is used to recover the unpumped xenon-124 from the decay tank and the circulation pipeline into the recovery tank, and then the xenon-124 is condensed through freezing.

[0015] Optionally, if the initial mixture further includes helium and the circulation pipeline is also equipped with a circulation pump, the method further includes: Separate the helium gas from the initial gas mixture.

[0016] Optionally, separating helium from the initial gas mixture includes: The adsorption device is connected to the irradiation device, and one end of the circulation pipeline is connected to the downstream outlet of the adsorption device, while the other end is connected to the return inlet of the irradiation device to form a circulation loop. The iodine removal tank is then connected to the circulation loop. The iodine removal tank is cooled down, the circulation pump is started to drive the gas to flow in the circulation loop, the first control valve is closed so that all the gas in the circulation pipeline flows through the iodine removal tank, and the second control valve and the third control valve are opened at the same time. The above-mentioned cycle is maintained for a preset time, and the iodine removal tank causes xenon-124, xenon-125, iodine-125 and iodine-126 in the gas to condense in the iodine removal tank through the freezing effect of the iodine removal tank; When the pressure inside the iodine removal tank is constant, close the third control valve and the circulation pump; The gas storage tank is connected to the iodine removal tank. The vacuum pump is started to pump the helium separated in the circulation loop into the gas storage tank. After the helium is pumped out, the vacuum pump is turned off and the connection between the gas storage tank and the iodine removal tank is cut off, thus completing the separation and storage of helium.

[0017] By utilizing the above technical solution, this application provides a separation, purification, and recovery system and method for iodine-125 production. By installing an adsorption device downstream of the irradiation unit, the initial mixed gas generated by irradiation can undergo primary iodine removal treatment, initially removing some iodine impurities. Then, using an iodine removal tank connected in parallel with the first control valve on the circulation pipeline, the gas is cooled and recovered using a negative pressure difference and heated to a first preset temperature, causing xenon-124 and xenon-125 to sublimate into a xenon mixture, achieving secondary iodine removal. This effectively separates iodine impurities such as iodine-126, significantly improving the purity of subsequent products and ensuring the quality of iodine-125 products. Through connection with a second control valve... The decay tank with parallel valves uses negative pressure differential to freeze and recover the xenon gas mixture after secondary iodine removal, providing a stable environment for the decay of xenon-125 to generate iodine-125. After decay, the temperature is raised to ensure that only xenon-124 sublimates, avoiding xenon-125 waste, improving the utilization rate of intermediate products, and ensuring the production of iodine-125. Through a gas storage tank connected in parallel with the third control valve and equipped with a vacuum pump and an exhaust pump, the sublimated xenon-124 in the decay tank can be pumped and stored, and xenon-124 can be sent back to the irradiation device for reprocessing as needed, forming a closed-loop reuse of raw material gas, significantly improving the xenon-124 recovery and reuse rate and reducing raw material costs.

[0018] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0019] Figure 1 This invention provides a schematic diagram of the structure of a separation, purification, and recovery system for iodine-125 production according to an embodiment of this application. Figure 2 A flowchart of a separation, purification and recovery method for iodine-125 production provided in an embodiment of this application is shown.

[0020] The reference numerals in the attached figures are as follows: 1. Irradiation device; 2. Adsorption device; 3. Circulation pipeline; 4. Iodine removal tank; 5. Decay tank; 6. Gas storage tank; 7. Recovery tank; 8. Refrigeration device; F1, First control valve; F2, Second control valve; F3, Third control valve; F4, Fourth control valve; F5, Fifth control valve; F6, Sixth control valve; F7, Seventh control valve; F8, Eighth control valve; F9, Ninth control valve; F10, Tenth control valve; F11, Eleventh control valve; F12, Twelfth control valve; F13, Thirteenth control valve; F14, Fourteenth control valve; F15, Fifteenth control valve; S1, First isolation valve; S2, Second isolation valve; S3, Third isolation valve; S4, Fourth isolation valve; S5, Fifth isolation valve; S6, Sixth isolation valve; B1. Suction pump; B2. Exhaust pump; B3. Circulation pump; P1, first pressure sensor; P2, second pressure sensor; P3, third pressure sensor. Detailed Implementation

[0021] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0023] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] The preferred embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0025] See Figure 1 As shown in the embodiments of this application, a separation, purification, and recovery system for iodine-125 production is provided, including an irradiation device 1, an adsorption device 2, and a circulation pipeline 3. The irradiation device 1 is used to irradiate the raw gas with neutrons to generate an initial mixed gas. The adsorption device 2 is arranged downstream of the irradiation device 1 along the flow path and is connected to the irradiation device 1, used to perform primary iodine removal treatment on the initial mixed gas output from the irradiation device 1. One end of the circulation pipeline 3 is connected to the downstream outlet of the adsorption device 2, and the other end is connected to the return inlet of the irradiation device 1. At least one first control valve F1, at least one second control valve F2, and at least one third control valve F3 are sequentially arranged along the flow path of the circulation pipeline 3. Among them, the first control valve F1 is connected in parallel with an iodine removal tank 4, which is used to refrigerate and recover the iodine through a negative pressure difference. The gas in the circulation pipeline 3 is collected and heated to a first preset temperature, causing xenon-124 and xenon-125 to sublimate into gas to form a xenon gas mixture, thus achieving secondary iodine removal. The second control valve F2 is connected in parallel with a decay tank 5, which is used to recover the xenon gas mixture obtained after secondary iodine removal by freezing through negative pressure difference, so that xenon-125 can decay into iodine-125, and be heated to the first preset temperature, causing xenon-124 to sublimate into gas. The third control valve F3 is connected in parallel with a gas storage tank 6, and a vacuum pump B1 is installed on the inlet pipeline of the gas storage tank 6. The vacuum pump B1 is used to pump the xenon-124 formed after heating in the decay tank 5 into the gas storage tank 6 for storage. The outlet pipeline of the gas storage tank 6 is equipped with an exhaust pump B2, which is used to return the xenon-124 stored in the gas storage tank 6 to the irradiation device 1 for reprocessing as needed.

[0026] The iodine-125 production separation, purification, and recovery system provided in the embodiments of this application, by setting an adsorption device 2 downstream of the irradiation device 1, can perform primary iodine removal treatment on the initial mixed gas generated by irradiation, initially removing some iodine impurities; then, by using an iodine removal tank 4 connected in parallel with the first control valve F1 on the circulation pipeline 3, the gas is frozen and recovered using negative pressure difference and heated to a first preset temperature, so that xenon-124 and xenon-125 are sublimated into a xenon gas mixture, achieving secondary iodine removal, effectively separating iodine impurities such as iodine-126, significantly improving the purity of subsequent products, and ensuring the quality of iodine-125 products; through a system connected in parallel with the second control valve F2... Decay tank 5 uses negative pressure differential to freeze and recover the xenon gas mixture after secondary iodine removal, providing a stable environment for the decay of xenon-125 to generate iodine-125. After decay, the temperature is raised to ensure that only xenon-124 sublimates, avoiding waste of xenon-125, improving the utilization rate of intermediate products, and ensuring the production of iodine-125. Through the gas storage tank 6 connected in parallel with the third control valve F3 and equipped with the suction pump B1 and exhaust pump B2, the sublimated xenon-124 in decay tank 5 can be pumped and stored, and xenon-124 can be sent back to the irradiation device 1 for reprocessing as needed, forming a closed-loop reuse of raw material gas, which significantly improves the xenon-124 recovery and reuse rate and reduces raw material costs.

[0027] In the practical application of the separation, purification and recovery system for iodine-125 production, the main component of the raw material gas used for production is xenon-124. During use, it is fed into irradiation device 1, where a nuclear reaction is initiated by neutron irradiation. The initial mixed gas generated after the reaction contains at least three types of substances: unreacted raw material xenon-124, the direct product of the nuclear reaction xenon-125, and impurities iodine-125 and iodine-126 generated during the reaction. In this embodiment, irradiation device 1 is made of aluminum alloy 6061 and has an overall cylindrical structure. This material is resistant to radiation and iodine corrosion, and can adapt to long-term nuclear reaction environments. The device also includes gas inlets and outlets, and the inlet interfaces are sealed using argon arc welding to effectively prevent gas leakage and ensure system operational stability.

[0028] In this configuration, along the flow path of the initial mixed gas, the adsorption device 2 is connected downstream of the irradiation device 1 via a pipeline, so that the initial mixed gas, after exiting the irradiation device 1, first enters the adsorption device 2. Here, the adsorption device 2 is used to perform primary iodine removal treatment on the initial mixed gas.

[0029] Specifically, the adsorption device 2 is constructed entirely of stainless steel, with a cylindrical internal cavity equipped with two sealing caps and two inlet / outlet side openings. All sealing caps and inlet / outlet side openings are sealed with rubber rings to prevent gas leakage. A cylindrical inner core is placed within the internal cavity, filled with millimeter-sized solid inorganic adsorbent materials such as activated carbon, silver-impregnated activated carbon, or copper-based platinum. The inner core is flanked by 50-100 mesh screens and sealing caps. The adsorbent material is larger than the screen pore size to prevent it from entering subsequent pipelines and causing blockages or contamination. In actual operation, the adsorption device 2 processes the initial mixed gas output from the irradiation device 1. The internal adsorbent material adsorbs and traps iodine-125 and iodine-126 in the initial mixed gas, initially separating a xenon-containing mixed gas whose main components are xenon-124 and xenon-125, with possible residual traces of iodine-125 and iodine-126. This lays the foundation for subsequent secondary iodine removal.

[0030] In order to form a circulation loop to realize gas flow, the system is equipped with a circulation pipeline 3. One end of the circulation pipeline 3 is connected to the downstream outlet of the adsorption device 2 to receive the xenon-containing mixed gas after primary iodine removal, and the other end is connected to the return inlet of the irradiation device 1 to send the reused xenon-124 back to the irradiation device 1, thus forming a closed loop of purification-recovery-reuse.

[0031] Specifically, a first control valve F1, a second control valve F2, and a third control valve F3 are sequentially arranged along the gas flow direction on the circulation pipeline 3. Each valve is connected in parallel to a functional tank. The gas flow direction can be controlled by opening and closing the valves, allowing the gas to enter the functional tank for specific treatment or controlling the gas flow within the circulation pipeline 3. The first control valve F1 is connected in parallel to an iodine removal tank 4, the second control valve F2 is connected in parallel to a decay tank 5, and the third control valve F3 is connected in parallel to a gas storage tank 6. It should be noted that at least one of each of the first, second, and third control valves F1, and at least one of each of the corresponding iodine removal tank 4, decay tank 5, and gas storage tank 6 are provided. In this embodiment, one iodine removal tank 4 and one gas storage tank 6 are provided, and two decay tanks 5 are provided.

[0032] The iodine removal tank 4 features a quick-release stainless steel structure, facilitating cleaning, maintenance, or replacement of the tank's internal cavity and preventing residual impurities from affecting subsequent iodine removal. The internal volume of iodine removal tank 4 ranges from 50 to 500 ml, and it has two inlets and outlets, each equipped with a valve for sealing. Furthermore, the material of iodine removal tank 4 is resistant to cryogenic temperatures and iodine corrosion, and its clean internal cavity prevents impurities from falling in. Its function is to freeze and retain residual iodine-125 and iodine-126 after primary iodine removal, thus achieving secondary iodine removal.

[0033] Specifically, when the first control valve F1 is closed and the valve at the inlet of the iodine removal tank 4 is opened, connecting the iodine removal tank 4 to the circulation pipeline 3, the xenon-containing gas mixture after primary iodine removal will enter the iodine removal tank 4. During actual operation, the iodine removal tank 4 is cooled to maintain the required freezing environment for xenon, such as -120 degrees Celsius, ensuring that the iodine removal tank 4 is always under vacuum. Under the suction of the negative pressure, the xenon-containing gas mixture in the circulation pipeline 3 is completely drawn into the iodine removal tank 4, and all components, including residual iodine, xenon-124, and xenon-125, are temporarily stored in the iodine removal tank 4 due to low-temperature crystallization. When the absolute pressure inside the iodine removal tank 4 reaches 0, the xenon-containing gas mixture has completely entered the iodine removal tank 4 and been frozen and crystallized. At this time, the iodine removal tank 4 is heated to the first preset temperature, preferably between -85 and -25 degrees Celsius. At this temperature, xenon will sublimate into gas, while iodine, due to its higher melting point, remains in a crystalline state. The sublimated gas at this time is the xenon gas mixture, which contains only xenon-124 and xenon-125 and no iodine impurities, thereby achieving complete separation of iodine and xenon and completing the secondary iodine removal.

[0034] The decay tank 5 has the same structure, material and internal volume as the iodine removal tank 4. It is used to freeze and recover xenon-124 and xenon-125 obtained after secondary iodine removal, and to supply xenon-125 to decay into iodine-125.

[0035] Specifically, when the second control valve F2 is closed and the valves at the outlet of the iodine removal tank 4 and the inlet of the decay tank 5 are opened, connecting the decay tank 5 and the iodine removal tank 4, the xenon gas mixture after secondary iodine removal will enter the decay tank 5. During actual operation, the decay tank 5 is cooled to maintain the required freezing environment for xenon, such as -120 degrees Celsius, ensuring that the decay tank 5 is always under vacuum. Under the suction of the negative pressure, the xenon gas mixture in the iodine removal tank 4 is completely drawn into the decay tank 5, and all components, including xenon-124 and xenon-125, are temporarily stored in the decay tank 5 due to low-temperature crystallization. When the absolute pressure in both decay tank 5 and iodine removal tank 4 reaches 0, it indicates that the iodine-xenon separation is complete and decay tank 5 has finished recovering the xenon gas mixture, namely xenon-124 and xenon-125. At this point, the valves at the outlet of iodine removal tank 4 and the inlet of decay tank 5 are closed, allowing decay tank 5 to maintain a low-temperature environment, preferably frozen for 3 to 7 days, waiting for xenon-125 to undergo nuclear decay according to its own half-life characteristics, completely converting into iodine-125. At this time, the components in the tank become crystalline iodine-125 and xenon-124. After decay is complete, decay tank 5 is heated to a first preset temperature, preferably between -85 and -25 degrees Celsius. At this temperature, xenon-124 will sublimate into gas, while iodine-125 remains crystalline, thus achieving the separation of the target product of iodine-125 and the raw material of xenon-124.

[0036] The gas storage tank 6 is made of stainless steel, and its inner cavity can be configured with a spiral hole structure to increase the airflow rate. The gas storage tank 6 has two inlets and outlets, each equipped with a valve and a pump. The valves serve to close and seal the system, while the pumps recover xenon-124 and supply it to the irradiation device 1. The inlet of the gas storage tank 6 is equipped with a vacuum pump B1, and the outlet is equipped with an exhaust pump B2. In this embodiment, both the vacuum pump B1 and the exhaust pump B2 can be dry pumps with a vacuum level not exceeding 10 Pa, meeting the negative pressure environment requirements for gas transfer within the decay tank 5 and gas storage and transportation in the gas storage tank 6. Furthermore, it has an extremely low leakage rate, effectively preventing gas leakage during extraction or transportation, ensuring the stability of the gas composition and the safety of operation within the system. In terms of pumping speed adjustment, the pumping speed controllable range of the vacuum pump B1 and the exhaust pump B2 covers from zero to twenty liters per minute, and supports adjustment in multiple levels. In actual use, the appropriate pumping speed level can be flexibly selected according to different working conditions such as the pumping requirements of xenon-124 in decay tank 5 and the rate requirements of the return xenon-124 from storage tank 6 to irradiation device 1, so as to ensure that the gas transfer efficiency is compatible with the rhythm of the overall process flow of the system.

[0037] Specifically, when the third control valve F3 is closed and the valves at the outlet of decay tank 5 and the inlet of storage tank 6 are opened, connecting storage tank 6 to decay tank 5, the suction pump B1 is activated to pump xenon-124 from decay tank 5 into storage tank 6. Simultaneously, storage tank 6 is connected to irradiation device 1 via exhaust pump B2, allowing the pure xenon-124 in storage tank 6 to be returned to irradiation device 1 for neutron irradiation again, thus forming a closed-loop process of raw material-irradiation-recovery-re-irradiation.

[0038] It should be noted that in this embodiment, the vacuum negative pressure state required for the operation of the iodine removal tank 4 and the decay tank 5 is achieved by a preset vacuum pump before the system is officially put into operation. The specific operation is as follows: After connecting the vacuum pump to the circulation pipeline 3, the vacuum pump is turned on to perform a vacuum operation on the circulation pipeline 3 and the inside of the iodine removal tank 4 and the decay tank 5. After the pressure inside the tank reaches the vacuum negative pressure standard and is confirmed by the pressure sensor equipped in the system, the valve connecting the vacuum pump to the tank and pipeline is closed, so that the iodine removal tank 4 and the decay tank 5 maintain a stable vacuum negative pressure environment, which lays the foundation for the subsequent recovery of gas by negative pressure suction and ensures complete gas transfer.

[0039] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 1 As shown, a circulation pump B3 is also provided on the circulation pipeline 3. The circulation pump B3 is located upstream of the first control valve F1 near the adsorption device 2 along the flow direction of the circulation pipeline 3, and is used to provide power for the flow of gas in the circulation pipeline 3.

[0040] In this embodiment, by installing a circulation pump B3 in the circulation pipeline 3, upstream of the first control valve F1 near the adsorption device 2 along the flow path, a stable and controllable power source can be provided for the gas flow in the circulation pipeline 3. This avoids problems such as flow rate attenuation and poor flow due to pipeline resistance, pressure drop along the device, etc., during the gas circulation process. It ensures that the xenon-containing mixed gas after the first stage of iodine removal by the adsorption device 2 can be efficiently and stably transported to the downstream iodine removal tank 4, ensuring that the subsequent processes such as the second stage of iodine removal and xenon-125 decay can proceed in an orderly manner according to the preset process.

[0041] In the circulation pipeline 3 of the iodine-125 production separation, purification, and recovery system, the circulation pump B3 is a dry pump type. Its circulation flow rate can be adjusted from zero to ten liters per minute, allowing for flexible adjustment of the flow rate according to the gas processing requirements at different stages of the system, thus adapting to the conveying efficiency of the xenon-containing gas mixture after primary iodine removal. Simultaneously, the circulation pump B3 has an extremely low leakage rate, effectively preventing gas leakage during pipeline transport, ensuring the stability of the gas composition and operational safety within the system. Furthermore, the gas-contacting material is made of fluororubber, which possesses excellent corrosion resistance and sealing properties, adapting to the iodine impurities and other media environments that may exist within the system. This prevents material corrosion from affecting pump performance or generating impurities that contaminate the gas, further ensuring the long-term stable operation of the circulation pump B3 and the overall separation and purification effect of the system.

[0042] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 1 As shown, at least one fourth control valve F4 is also provided on the circulation pipeline 3. The fourth control valve F4 is located in the pipeline section between the second control valve F2 and the third control valve F3. The fourth control valve F4 is connected in parallel with a recovery tank 7. The recovery tank 7 is configured such that when the pump B1 on the inlet pipeline of the gas storage tank 6 cannot completely pump the remaining xenon-124 in the decay tank 5 and the circulation pipeline 3 into the gas storage tank 6 for storage, the remaining xenon-124 in the decay tank 5 and the circulation pipeline 3 is recovered by connecting to the circulation pipeline 3 and using a negative pressure differential freezing method.

[0043] In this embodiment, a fourth control valve F4 is installed on the pipe section between the second control valve F2 and the third control valve F3 in the circulation pipeline 3, and this fourth control valve F4 is connected in parallel with the recovery tank 7, thus establishing a dual guarantee mechanism for xenon-124 recovery. When the suction pump B1 at the inlet of the gas storage tank 6 cannot completely pump the xenon-124 from the decay tank 5 and the circulation pipeline 3 into the gas storage tank 6 due to insufficient negative pressure or pipeline residue, the recovery tank 7 can be connected to the circulation pipeline 3 by opening the fourth control valve F4. The remaining xenon-124 can then be captured and recovered a second time by using the negative pressure differential freezing method. This effectively avoids the waste of xenon-124 raw materials caused by incomplete single pumping and further improves the overall recovery and reuse rate of xenon-124.

[0044] The recovery tank 7 has the same structure, material, and internal volume as the decay tank 5 and the iodine removal tank 4. It is used when the pump B1 at the inlet of the gas storage tank 6 cannot completely pump the remaining xenon-124 in the decay tank 5 and the circulation pipeline 3 to the gas storage tank 6. By connecting to the circulation pipeline 3, it uses its own characteristics of being resistant to deep cryogenic temperature and iodine corrosion, as well as its suitable internal volume, to effectively recover the xenon-124 that was not pumped out by means of negative pressure differential freezing. This ensures that xenon-124 is collected as much as possible, reduces raw material waste, and ensures the integrity and efficiency of the entire system in recovering xenon-124.

[0045] Specifically, when the fourth control valve F4 is closed and the valves at the inlet and outlet of the recovery tank 7 are opened, connecting the recovery tank 7 to the circulation pipeline 3, the unextracted xenon-124 in the decay tank 5 and circulation pipeline 3 can enter the recovery tank 7. During actual operation, the recovery tank 7 is cooled to a required freezing environment for xenon, such as -120 degrees Celsius, and maintained under vacuum. Under the suction of this negative pressure, the unextracted xenon-124 in the decay tank 5 and circulation pipeline 3 is drawn into the recovery tank 7 and condenses into solid crystals due to the low temperature, temporarily stored inside the tank. When the absolute pressure inside the recovery tank 7 reaches 0, it indicates that the remaining xenon-124 has completely entered the recovery tank 7 and formed frozen crystals. At this point, the valves at the inlet and outlet of the recovery tank 7 can be closed. Subsequently, since the recovery tank 7 is also a quick-release stainless steel structure, solid xenon-124 can be directly recovered by disassembling the recovery tank 7 or by heating the recovery tank 7 to sublimate the solid xenon-124 into gas. These gases can then be transferred to the gas storage tank 6 or directly sent back to the irradiation device 1, thereby realizing the recovery and reuse of solid xenon-124.

[0046] It should be noted that in this embodiment, the vacuum negative pressure state required for the operation of the recovery tank 7, the iodine removal tank 4, and the decay tank 5 is achieved by a pre-set vacuum pump before the system officially starts operating. The specific operation of this part will not be described in detail here.

[0047] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 1 As shown, the iodine removal tank 4 is connected to a first pressure sensor P1, the decay tank 5 is connected to a second pressure sensor P2, and the recovery tank 7 is connected to a third pressure sensor P3.

[0048] In this embodiment, by connecting a first pressure sensor P1 to the iodine removal tank 4, a second pressure sensor P2 to the decay tank 5, and a third pressure sensor P3 to the recovery tank 7, the pressure status inside each functional tank can be monitored in real time and accurately. For the iodine removal tank 4, the first pressure sensor P1 can confirm whether the absolute pressure inside the tank has reached 0, thereby determining whether the xenon-containing gas mixture has completely entered the iodine removal tank 4 and frozen and crystallized, ensuring the thorough separation of iodine and xenon during secondary iodine removal and avoiding the impact of residual gas on the iodine removal effect. For the decay tank 5, the pressure sensor P1 can be used to... The second pressure sensor P2 can verify whether the tank is under vacuum and negative pressure and whether the xenon gas mixture has been completely recovered. It can also help determine the stability of the tank environment during the xenon-125 decay process, ensuring that the decay reaction proceeds fully and guaranteeing the yield of the target iodine-125 product. For the recovery tank 7, the third pressure sensor P3 can monitor whether the absolute pressure inside the tank has reached 0, confirming whether the remaining xenon-124 in the decay tank 5 and circulation pipeline 3 has been completely sucked into the recovery tank 7, avoiding waste of xenon-124 raw material due to incomplete recovery and further improving the raw material reuse rate.

[0049] Among them, the first pressure sensor P1, the second pressure sensor P2, and the third pressure sensor P3 can be pressure gauges or pressure gauges.

[0050] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 1 As shown, the separation, purification and recovery system for iodine-125 production also includes a refrigeration unit 8 for temperature control of the iodine removal tank 4, decay tank 5 and recovery tank 7. The refrigeration unit 8 is equipped with temperature control chambers that correspond one-to-one with the number of iodine removal tanks 4, decay tanks 5 and recovery tanks 7. Each temperature control chamber is used to accommodate the corresponding iodine removal tank 4, decay tank 5 or recovery tank 7, and each temperature control chamber has an independent heating control module and a cooling control module.

[0051] In this embodiment, by setting up a refrigeration device 8 with temperature-controlled chambers corresponding one-to-one with the iodine removal tank 4, decay tank 5, and recovery tank 7, and by equipping each temperature-controlled chamber with an independent heating and cooling control module, precise and independent temperature control of each functional tank can be achieved. On the one hand, it can provide suitable and stable temperature loops for the iodine removal tank 4 to refrigerate and recover the xenon-containing gas mixture and heat it to a first preset temperature to separate iodine and xenon; for the decay tank 5 to refrigerate and recover the xenon gas mixture and heat it after decay to separate xenon-124 and iodine-125; and for the recovery tank 7 to refrigerate and recover the remaining xenon-124. The system ensures that the temperature conditions for processes such as secondary iodine removal, xenon-125 decay, and residual xenon-124 recovery are precisely met, guaranteeing the thorough separation of iodine and xenon, the sufficiency of xenon-125 decay, and the effectiveness of xenon-124 recovery. On the other hand, independent temperature control in each temperature-controlled chamber avoids mutual interference between different functional tanks due to differences in temperature requirements. This allows each process step to flexibly and efficiently adjust the temperature according to actual needs, significantly improving the system's adaptability and operational stability to different process steps, and further ensuring the quality of iodine-125 products and the recycling rate of xenon-124.

[0052] In the case where the system includes an iodine removal tank 4, two decay tanks 5 and a recovery tank 7, the refrigeration unit 8 is equipped with four temperature control chambers. Each temperature control chamber is an independent temperature control space, and its size and sealing performance are adapted to the corresponding tank.

[0053] Specifically, for the four independent temperature-controlled chambers corresponding to one iodine removal tank 4, two decay tanks 5, and one recovery tank 7 in the system, each temperature-controlled chamber is equipped with a heating control module and a cooling control module adapted to its own functional requirements. Regarding the heating control module, the heating methods for the four temperature-controlled chambers include, but are not limited to, electromagnetic induction heating and resistance heating. Taking electromagnetic induction heating as an example, an electromagnetic induction coil matching the size of the corresponding tank can be installed inside each temperature-controlled chamber. Utilizing the tank's own magnetic properties, eddy currents are generated in the tank under electromagnetic induction, causing it to heat up, thereby raising the temperature of the substances inside the tank. If resistance heating is used, suitable resistance heating elements can be laid on the inner wall of the temperature-controlled chamber, transferring heat to the tank through resistance heating to achieve the heating purpose. Regarding the cooling control module, the cooling methods for the four temperature-controlled chambers include, but are not limited to, liquid nitrogen cooling and electric refrigeration cooling. Taking liquid nitrogen cooling as an example, each temperature control chamber is independently equipped with a liquid nitrogen storage tank, liquid nitrogen delivery pipeline, and atomizing spray device. The atomizing spray device is evenly distributed along the inner wall of the temperature control chamber. During operation, liquid nitrogen is transported from the storage tank to the atomizing spray device through the delivery pipeline, where it is atomized into tiny droplets and evenly sprayed onto the surface of the tank. The tank is rapidly cooled by absorbing heat through the vaporization of the liquid nitrogen. If electric cooling is used, a suitable semiconductor cooling chip can be integrated into the temperature control chamber to reduce the ambient temperature inside the chamber using the Peltier effect, thereby providing a low-temperature environment for the tank.

[0054] In some possible implementations disclosed in this application, see [link to relevant documentation]. Figure 1 As shown, the inlet pipe of the iodine removal tank 4 is sequentially equipped with a fifth control valve F5 and a first isolation valve S1, wherein the first isolation valve S1 is located downstream of the fifth control valve F5; the outlet pipe of the iodine removal tank 4 is sequentially equipped with a second isolation valve S2 and a sixth control valve F6, wherein the second isolation valve S2 is located upstream of the sixth control valve F6; the inlet pipe of the decay tank 5 is sequentially equipped with a seventh control valve F7 and a third isolation valve S3, wherein the third isolation valve S3 is located downstream of the seventh control valve F7; the outlet pipe of the decay tank 5 is sequentially equipped with a fourth isolation valve S4 and an eighth control valve F8, wherein the fourth isolation valve S4 is located downstream of the fifth control valve F5. Upstream of control valve F8; a ninth control valve F9 is installed on the inlet pipe of gas storage tank 6, which is located downstream of suction pump B1; a tenth control valve F10 is installed on the outlet pipe of gas storage tank 6, which is located upstream of exhaust pump B2; an eleventh control valve F11 and a fifth isolation valve S5 are sequentially installed on the inlet pipe of recovery tank 7, with the fifth isolation valve S5 located downstream of the eleventh control valve F11; a sixth isolation valve S6 and a twelfth control valve F12 are sequentially installed on the outlet pipe of recovery tank 7, with the sixth isolation valve S6 located upstream of the twelfth control valve F12.

[0055] To control the flow of the initial mixed gas from irradiation device 1 into adsorption device 2, enabling flexible control of the start-up and shutdown of the primary iodine removal process, and to promptly disconnect the adsorption device 2 from irradiation device 1 when maintenance, replacement of internal adsorption materials, or system malfunctions occur, thus preventing gas leakage or cross-flow of gases between different pipelines, a thirteenth control valve F13 is installed on the connecting pipeline between adsorption device 2 and irradiation device 1. To control the timing and flow rate of the xenon-containing mixed gas after primary iodine removal into circulation pipeline 3, preventing disordered flow of the xenon-containing mixed gas within circulation pipeline 3, and to facilitate gas treatment or maintenance in downstream functional tanks such as iodine removal tank 4 and decay tank 5, a thirteenth control valve F13 is installed. The connection between the adsorption device 2 and the circulation pipeline 3 is cut off to ensure an independent operating environment for downstream processes. A fourteenth control valve F14 is installed at the end of the circulation pipeline 3 that connects to the downstream outlet of the adsorption device 2. In order to control the process of returning the recovered xenon-124 to the irradiation device 1 and ensure that the returned xenon-124 can enter the irradiation device 1 as needed and stably to participate in re-irradiation, and to cut off the connection between the circulation pipeline 3 and the irradiation device 1 when the irradiation device 1 is replenished with raw material gas, maintained or adjusted, so as to avoid the gas in the circulation pipeline 3 from interfering with the reaction environment in the irradiation device 1, a fifteenth control valve F15 is installed at the end of the circulation pipeline 3 that connects to the return inlet of the irradiation device 1.

[0056] Specifically, the first control valve F1, the second control valve F2, the third control valve F3, the fourth control valve F4, the fifth control valve F5, the sixth control valve F6, the seventh control valve F7, the eighth control valve F8, the ninth control valve F9, the tenth control valve F10, the eleventh control valve F11, the twelfth control valve F12, the thirteenth control valve F13, the fourteenth control valve F14, and the fifteenth control valve F15 are all pneumatic valves; the first isolation valve S1, the second isolation valve S2, the third isolation valve S3, the fourth isolation valve S4, the fifth isolation valve S5, and the sixth isolation valve S6 are all manual valves. Understandably, pneumatic valves, capable of automated operation, can be used as the first to fifteenth control valves (F15) to meet the precise timing control requirements of the gas flow in the entire iodine-125 production separation, purification, and recovery system. During system operation, each pneumatic valve can automatically switch its on / off state via the central control system based on preset process flows or real-time monitoring data such as pressure and temperature of each tank. This eliminates the need for manual intervention, ensuring the orderly connection of each process step, significantly improving system efficiency and stability, while reducing errors or safety risks that may arise from manual operation. Meanwhile, the first to sixth isolation valves... S6 is configured as a manual valve, enabling reliable disconnection and sealing of pipelines and tanks during system maintenance, cleaning of iodine removal tank 4, xenon transfer of recovery tank 7, and other tank disassembly and assembly scenarios, as well as in case of sudden abnormalities. These operations are usually infrequent and require high flexibility in timing. The manual valve has a relatively simple structure, strong sealing performance, and low failure rate. During manual operation, the valve's open / closed status can be more intuitively confirmed, ensuring a complete seal between pipelines and tanks in scenarios requiring tank isolation. This effectively prevents gas leakage or cross-flow of gas between different pipelines, further ensuring the safety and operational reliability during system maintenance.

[0057] Furthermore, as a supporting implementation scheme for the aforementioned separation, purification, and recovery system for iodine-125 production, to standardize the system operation process, clarify the operational logic of each functional module, and ensure the orderly progress of the entire process from raw material gas irradiation to iodine-125 purification and xenon-124 recovery and reuse, embodiments of this application also provide a separation, purification, and recovery method for iodine-125 production, see [link to relevant documentation]. Figure 2 As shown, the method includes: Step S101: The raw material gas is irradiated with neutrons by irradiation device 1 to generate an initial mixed gas, the initial mixed gas including at least iodine-125, iodine-126, xenon-124 and xenon-125; Step S201: Control the adsorption device 2 to connect with the irradiation device 1, so that the initial mixed gas enters the adsorption device 2, and the adsorption device 2 adsorbs and retains iodine-125 and iodine-126 in the initial mixed gas to complete the first-stage iodine removal treatment. Step S301: Connect one end of the control circulation pipeline 3 to the downstream outlet of the adsorption device 2 and the other end to the return inlet of the irradiation device 1 to form a circulation loop. At the same time, close the first control valve F1, the second control valve F2 and the third control valve F3 on the circulation pipeline 3, and connect the iodine removal tank 4 to the circulation pipeline 3. Step S401: Cool down the iodine removal tank 4. At the same time, use the negative pressure difference inside the iodine removal tank 4 to pump the gas that has passed the first stage of iodine removal in the circulation pipeline 3 into the iodine removal tank 4. The gas is condensed by freezing. After the gas is recovered, cut off the connection between the inlet pipeline of the iodine removal tank 4 and the circulation pipeline 3. Heat up the iodine removal tank 4 to the first preset temperature. The condensed xenon-124 and xenon-125 sublimate to form a xenon gas mixture. The remaining iodine-125 and iodine-126 remain in the iodine removal tank 4, completing the second stage of iodine removal. Step S501: Cool the decay tank 5 while controlling the connection between the decay tank 5 and the iodine removal tank 4. Use the negative pressure difference inside the decay tank 5 to draw the xenon gas mixture formed in the iodine removal tank 4 into the decay tank 5. The xenon gas mixture is condensed by freezing. After the xenon gas mixture is recovered, cut off the connection between the decay tank 5 and the iodine removal tank 4, so that the xenon gas mixture can stand in the decay tank 5 for xenon-125 to decay into iodine-125. After the decay is completed, raise the temperature inside the decay tank 5 to the first preset temperature so that xenon-124 sublimates to form xenon gas. Step S601: Connect the gas storage tank 6 to the decay tank 5, and simultaneously start the vacuum pump B1 to pump the sublimated xenon-124 from the decay tank 5 into the gas storage tank 6. After the xenon-124 pumping is completed, turn off the vacuum pump B1 and disconnect the connection between the gas storage tank 6 and the decay tank 5 to complete the recovery and storage of xenon-124. Subsequently, according to production needs, the gas storage tank 6 can be connected to the irradiation device 1, and the xenon-124 stored in the gas storage tank 6 can be returned to the irradiation device 1 for reprocessing through the exhaust pump B2.

[0058] Here, when implementing the recovery method using the separation, purification, and recovery system for iodine-125 production, the raw material gas, whose main component is xenon-124, is first fed into a cylindrical irradiation device 1 made of aluminum alloy 6061. Neutron irradiation triggers a nuclear reaction to generate an initial mixed gas containing iodine-125, iodine-126, unreacted xenon-124, and the nuclear reaction product xenon-125. This process corresponds to step S101 in the method. Next, the thirteenth control valve F13 on the pipeline connecting the adsorption device 2 and the irradiation device 1 is opened, allowing the initial mixed gas to enter the adsorption device 2, which has a stainless steel shell and is filled with solid-phase inorganic adsorption materials such as activated carbon. The adsorption materials adsorb and retain iodine-125 and iodine-126 in the mixed gas, initially separating the xenon-containing mixed gas and completing the first-stage iodine removal treatment. This step corresponds to step S201. Next, open the fourteenth control valve F14 connecting the downstream outlet of the adsorption device 2 to the circulation pipeline 3 and the fifteenth control valve F15 connecting the return inlet of the irradiation device 1 to establish a circulation loop from the adsorption device 2 to the circulation pipeline 3 and then to the irradiation device 1. At the same time, close the first control valve F1, the second control valve F2 and the third control valve F3 on the circulation pipeline 3, and open the fifth control valve F5 and the first isolation valve S1 on the inlet pipeline of the iodine removal tank 4 to connect the iodine removal tank 4 to the circulation pipeline 3, corresponding to step S301. Subsequently, the temperature control chamber corresponding to the iodine removal tank 4 in the refrigeration unit 8 is activated, and the temperature of the iodine removal tank 4 is controlled to drop to -120 degrees Celsius. Utilizing the negative pressure difference inside the iodine removal tank 4 formed by the pre-vacuuming of the system, and with the power provided by the circulation pump B3, the xenon-containing gas mixture after the first stage of iodine removal in the circulation pipeline 3 is pumped into the iodine removal tank 4. The xenon-containing gas mixture condenses due to the low temperature. After the first pressure sensor P1 detects that the absolute pressure inside the iodine removal tank 4 is 0, confirming that the xenon-containing gas mixture has been recovered, the fifth control valve F5 and the first isolation valve S1 are closed to cut off the connection between the iodine removal tank 4 and the circulation pipeline 3. Then, the temperature control chamber controls the iodine removal tank 4 to rise to the first preset temperature of -85 to -25 degrees Celsius, so that the condensed xenon-124 and xenon-125 sublimate into a xenon gas mixture, while the residual iodine-125 and iodine-126 remain in the tank in a crystalline state, completing the second stage of iodine removal, corresponding to step S401.Next, the temperature control chamber corresponding to decay tank 5 in the refrigeration unit 8 is activated, and both decay tanks 5 are cooled to -120 degrees Celsius. The second isolation valve S2 and the sixth control valve F6 at the outlet of the iodine removal tank 4, as well as the seventh control valve F7 and the third isolation valve S3 at the inlet of the decay tank 5, are opened to connect the decay tank 5 and the iodine removal tank 4. The xenon gas mixture in the iodine removal tank 4 is drawn into the decay tank 5 using the negative pressure difference inside the decay tank 5, and the mixture condenses at low temperature. When the first pressure sensor P1 detects that the absolute pressure inside the iodine removal tank 4 is 0 and the second pressure sensor P1 detects that the absolute pressure inside the iodine removal tank 4 is 0, the xenon gas mixture in the iodine removal tank 4 is drawn into the decay tank 5. Sensor P2 detects that the absolute pressure inside decay tank 5 is 0, confirming that the xenon gas mixture recovery is complete. Then, the second isolation valve S2 and the sixth control valve F6 at the outlet of the iodine removal tank 4, as well as the seventh control valve F7 and the third isolation valve S3 at the inlet of decay tank 5, are closed, allowing decay tank 5 to remain at a low temperature in the temperature control chamber for 3 to 7 days to allow xenon-125 to decay into iodine-125. After decay is complete, the temperature control chamber corresponding to decay tank 5 in the refrigeration unit 8 is activated to raise the temperature of both decay tanks 5 to the first preset temperature, causing xenon-124 to sublimate, corresponding to step S501. Finally, open the fourth isolation valve S4 at the outlet of decay tank 5, the eighth control valve F8, and the ninth control valve F9 at the inlet of gas storage tank 6. Start the suction pump B1 at the inlet of gas storage tank 6 to pump the sublimated xenon-124 in decay tank 5 into the stainless steel gas storage tank 6. After the xenon-124 pumping is completed, close the suction pump B1 and related valves to complete the recovery and storage of xenon-124. Subsequently, according to production needs, open the tenth control valve F10 at the outlet of gas storage tank 6 and the fifteenth control valve F15 connecting the circulation pipeline 3 to the irradiation device 1, start the exhaust pump B2, and send the xenon-124 in gas storage tank 6 back to the irradiation device 1 for reprocessing, corresponding to step S601.

[0059] In some possible embodiments disclosed in this application, where a fourth control valve F4 is further provided on the circulation pipeline 3, and the fourth control valve F4 is connected in parallel with the recovery tank 7, the method further includes: When the pump B1 is unable to completely pump the remaining xenon-124 in the decay tank 5 and circulation pipeline 3 to the storage tank 6, the connection between the storage tank 6 and the decay tank 5 is cut off. At the same time, the recovery tank 7 is cooled down and connected to the circulation pipeline 3. The negative pressure difference inside the recovery tank 7 is used to recover the xenon-124 that was not pumped out in the decay tank 5 and circulation pipeline 3 into the recovery tank 7, and then the xenon-124 is condensed through freezing.

[0060] Here, if the vacuum pump B1 cannot completely pump out xenon-124, the fourth control valve F4 can be closed and the eleventh control valve F11, the fifth isolation valve S5, the sixth isolation valve S6, and the twelfth control valve F12 at the inlet and outlet of the recovery tank 7 can be opened. The recovery tank 7 is then connected to the circulation pipeline 3, and the temperature of the recovery tank 7 is controlled to -120 degrees Celsius by the refrigeration device 8. The remaining xenon-124 is recovered by freezing using the negative pressure difference. The pressure inside the recovery tank 7 is monitored by the third pressure sensor P3 to ensure that xenon-124 is fully recovered.

[0061] In some possible embodiments disclosed in this application, where the initial mixture also includes helium and a circulation pump B3 is provided on the circulation pipeline 3, the method further includes: Separate helium from the initial gas mixture.

[0062] In this embodiment, separating helium from the initial mixed gas can prevent helium from occupying the space in the pipeline and functional tank, diluting the concentration of other target gases, affecting the xenon recovery efficiency and the stability of the xenon-125 decay environment, ensuring that subsequent secondary iodine removal, xenon-125 decay and xenon-124 recovery processes are not disturbed, and ensuring that each process can be accurately carried out in the preset gas composition environment.

[0063] In the above embodiments, separating helium from the initial gas mixture includes: The adsorption device 2 is connected to the irradiation device 1, and at the same time, one end of the circulation pipeline 3 is connected to the downstream outlet of the adsorption device 2, and the other end is connected to the return inlet of the irradiation device 1 to form a circulation loop, and the iodine removal tank 4 is connected to the circulation loop. Cool the iodine removal tank 4, start the circulation pump B3 to drive the gas to flow in the circulation loop, close the first control valve F1 so that all the gas in the circulation pipeline 3 flows through the iodine removal tank 4, and at the same time open the second control valve F2 and the third control valve F3. If there is a fourth control valve F4 on the circulation pipeline 3, open the fourth control valve F4 at the same time. The above-mentioned cycle is maintained for a preset time, and the iodine removal tank 4 causes xenon-124, xenon-125, iodine-125 and iodine-126 in the gas to condense in the iodine removal tank 4 through the freezing effect; When the pressure inside the iodine removal tank 4 is constant, close the third control valve F3 and the circulation pump B3. Connect the gas storage tank 6 to the iodine removal tank 4, start the vacuum pump B1 to pump the helium separated in the circulation loop into the gas storage tank 6. After the helium is pumped out, turn off the vacuum pump B1 and disconnect the connection between the gas storage tank 6 and the iodine removal tank 4 to complete the separation and storage of helium.

[0064] Here, when the initial mixed gas still contains helium and the circulation pipeline 3 is equipped with a circulation pump B3, when separating the helium, first open the thirteenth control valve F13 on the pipeline connecting the adsorption device 2 and the irradiation device 1 to allow the initial mixed gas to enter the adsorption device 2 for primary iodine removal. At the same time, open the fourteenth control valve F14 connecting the downstream outlet of the adsorption device 2 and the fifteenth control valve F15 connecting the return inlet of the irradiation device 1 to establish a circulation loop from the adsorption device 2 to the circulation pipeline 3 and then to the irradiation device 1. Then close the first control valve F1 on the circulation pipeline 3 and open the fifth control valve F5 at the inlet of the iodine removal tank 4, the first isolation valve S1, and the second isolation valve S2 and the sixth control valve F6 at the outlet to connect the iodine removal tank 4 to the circulation loop. Then, the temperature control chamber corresponding to the iodine removal tank 4 in the refrigeration unit 8 is activated to cool the iodine removal tank 4 to -120 degrees Celsius. Then, the circulation pump B3 is activated and its circulation flow rate is adjusted to an appropriate level, such as 100 to 1000 ml per minute, driving the mixed gas after the first stage of iodine removal to flow in the circulation loop. At this time, because the first control valve F1 is closed, all the gas in the circulation pipeline 3 flows through the iodine removal tank 4, while the second control valve F2 and the third control valve F3 are kept open (if there is a fourth control valve F4, it is also open). This circulation state is maintained for a preset time, such as 10 to 50 minutes. During this process, xenon-124, xenon-125, residual iodine-125 and iodine-126 in the mixed gas will condense in the iodine removal tank 4 due to the low temperature freezing effect of the iodine removal tank 4, while helium will not condense due to its extremely low boiling point and will continue to flow in the circulation loop. When the first pressure sensor P1 detects that the pressure inside the iodine removal tank 4 remains constant, it indicates that the condensable gas inside the iodine removal tank 4 has basically condensed. At this time, the third control valve F3 and the circulation pump B3 are closed. Then, the ninth control valve F9 at the inlet of the gas storage tank 6 is opened, and the vacuum pump B1 is started. The negative pressure of the vacuum pump B1 is used to pump the uncondensed helium in the circulation loop into the gas storage tank 6. After the vacuum pump B1 has been running for a period of time and it is confirmed that the helium pumping is complete, the vacuum pump B1 and the ninth control valve F9 are closed, cutting off the connection between the gas storage tank 6 and the iodine removal tank 4, thereby completing the separation and storage of helium.

[0065] It will be readily understood by those skilled in the art that the aforementioned advantageous methods can be freely combined and superimposed without conflict.

[0066] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application. The above are merely preferred embodiments of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A separation, purification, and recovery system for iodine-125 production, characterized in that, include: An irradiation device used to irradiate the feed gas with neutrons to generate an initial mixture; An adsorption device is disposed downstream of the irradiation device along the flow path and connected to the irradiation device, and is used to perform primary iodine removal treatment on the initial mixed gas output by the irradiation device. A circulation pipeline is provided, with one end connected to the downstream outlet of the adsorption device and the other end connected to the return inlet of the irradiation device; at least one first control valve, at least one second control valve and at least one third control valve are sequentially provided along the flow path of the circulation pipeline. The first control valve is connected in parallel with an iodine removal tank. The iodine removal tank is used to freeze and recover the gas in the circulation pipeline through negative pressure difference, and heat it to a first preset temperature so that xenon-124 and xenon-125 sublimate into gas to form a xenon gas mixture, thereby achieving two-stage iodine removal. The second control valve is connected in parallel with a decay tank. The decay tank is used to recover the xenon gas mixture obtained after two-stage iodine removal by freezing through negative pressure difference, so that xenon-125 decays into iodine-125 and is heated to the first preset temperature so that xenon-124 sublimates into gas. The third control valve is connected in parallel to a gas storage tank. A vacuum pump is installed on the inlet pipe of the gas storage tank. The vacuum pump is used to pump the xenon-124 formed in the decay tank after heating into the gas storage tank for storage. An exhaust pump is installed on the outlet pipe of the gas storage tank. The exhaust pump is used to return the xenon-124 stored in the gas storage tank to the irradiation device for reprocessing as needed.

2. The separation, purification, and recovery system for iodine-125 production according to claim 1, characterized in that, The circulation pipeline is also equipped with a circulation pump, which is located upstream of the first control valve near the adsorption device along the flow direction of the circulation pipeline, and is used to provide power for the flow of gas in the circulation pipeline.

3. The separation, purification, and recovery system for iodine-125 production according to claim 1, characterized in that, The circulation pipeline is also equipped with at least one fourth control valve, which is located in the pipe section between the second control valve and the third control valve. The fourth control valve is connected in parallel to a recovery tank, which is configured such that when the pump on the gas storage tank inlet pipeline is unable to completely pump the remaining xenon-124 in the decay tank and the circulation pipeline into the gas storage tank, the remaining xenon-124 in the decay tank and the circulation pipeline is recovered by connecting to the circulation pipeline using a negative pressure differential freezing method.

4. The separation, purification, and recovery system for iodine-125 production according to claim 3, characterized in that, The iodine removal tank is connected to a first pressure sensor, the decay tank is connected to a second pressure sensor, and the recovery tank is connected to a third pressure sensor.

5. The separation, purification, and recovery system for iodine-125 production according to claim 3, characterized in that, Also includes: A refrigeration device for temperature control of the iodine removal tank, the decay tank, and the recovery tank; the refrigeration device is provided with temperature control chambers corresponding one-to-one with the iodine removal tank, the decay tank, and the recovery tank, each temperature control chamber is used to accommodate the corresponding iodine removal tank, the decay tank, or the recovery tank, and each temperature control chamber has an independent heating control module and a cooling control module.

6. The separation, purification, and recovery system for iodine-125 production according to claim 3, characterized in that, The inlet pipe of the iodine removal tank is provided with a fifth control valve and a first isolation valve in sequence, wherein the first isolation valve is located downstream of the fifth control valve; the outlet pipe of the iodine removal tank is provided with a second isolation valve and a sixth control valve in sequence, wherein the second isolation valve is located upstream of the sixth control valve. The decay tank has a seventh control valve and a third isolation valve installed sequentially on its inlet pipe, wherein the third isolation valve is located downstream of the seventh control valve; the decay tank has a fourth isolation valve and an eighth control valve installed sequentially on its outlet pipe, wherein the fourth isolation valve is located upstream of the eighth control valve. The gas storage tank is equipped with a ninth control valve on its inlet pipe, which is located downstream of the gas pump; the gas storage tank is equipped with a tenth control valve on its outlet pipe, which is located upstream of the exhaust pump. The inlet pipe of the recovery tank is provided with an eleventh control valve and a fifth isolation valve in sequence, wherein the fifth isolation valve is located downstream of the eleventh control valve; the outlet pipe of the recovery tank is provided with a sixth isolation valve and a twelfth control valve in sequence, wherein the sixth isolation valve is located upstream of the twelfth control valve.

7. A method for separation, purification, and recovery of iodine-125 for production, characterized in that, The method, applied to the separation, purification, and recovery system for iodine-125 production as described in any one of claims 1-6, comprises: The raw material gas is irradiated with neutrons by the irradiation device to generate the initial mixed gas, wherein the initial mixed gas includes at least iodine-125, iodine-126, xenon-124 and xenon-125. The adsorption device is connected to the irradiation device, so that the initial mixed gas enters the adsorption device. The adsorption device adsorbs and retains iodine-125 and iodine-126 in the initial mixed gas, thus completing the first-stage iodine removal treatment. One end of the circulation pipeline is connected to the downstream outlet of the adsorption device, and the other end is connected to the return inlet of the irradiation device to form a circulation loop. At the same time, the first control valve, the second control valve and the third control valve on the circulation pipeline are closed, and the iodine removal tank is connected to the circulation pipeline. The iodine removal tank is cooled down, and the gas that has undergone primary iodine removal in the circulation pipeline is pumped into the iodine removal tank using the negative pressure difference inside the iodine removal tank. The gas is condensed through freezing. After the gas is recovered, the connection between the inlet pipeline of the iodine removal tank and the circulation pipeline is cut off, and the iodine removal tank is heated up to the first preset temperature. The condensed xenon-124 and xenon-125 sublimate to form the xenon gas mixture, while the residual iodine-125 and iodine-126 remain in the iodine removal tank, thus completing the secondary iodine removal. The decay tank is cooled down while maintaining its connection with the iodine removal tank. The negative pressure difference inside the decay tank is used to draw the xenon gas mixture formed in the iodine removal tank into the decay tank. The xenon gas mixture is condensed through freezing. After the xenon gas mixture is recovered, the connection between the decay tank and the iodine removal tank is cut off, allowing the xenon gas mixture to stand in the decay tank for xenon-125 to decay into iodine-125. After the decay is complete, the temperature inside the decay tank is raised to the first preset temperature, causing xenon-124 to sublimate and form xenon gas. The gas storage tank is connected to the decay tank, and the vacuum pump is started to pump the sublimated xenon-124 in the decay tank into the gas storage tank. After the xenon-124 is pumped out, the vacuum pump is turned off and the connection between the gas storage tank and the decay tank is cut off, thus completing the recovery and storage of xenon-124. Subsequently, according to production needs, the gas storage tank can be connected to the irradiation device, and the xenon-124 stored in the gas storage tank can be returned to the irradiation device for reprocessing through the exhaust pump.

8. The separation, purification, and recovery method for iodine-125 production according to claim 7, characterized in that, If a fourth control valve is also provided on the circulation pipeline, and the fourth control valve is connected in parallel to a recovery tank, the method further includes: When the pump cannot completely pump the remaining xenon-124 from the decay tank and the circulation pipeline to the storage tank, the connection between the storage tank and the decay tank is cut off. At the same time, the recovery tank is cooled down and connected to the circulation pipeline. The negative pressure difference inside the recovery tank is used to recover the unpumped xenon-124 from the decay tank and the circulation pipeline into the recovery tank, and then the xenon-124 is condensed through freezing.

9. The method for separation, purification, and recovery of iodine-125 for production according to claim 7, characterized in that, If the initial gas mixture also includes helium and a circulation pump is provided on the circulation pipeline, the method further includes: Separate the helium gas from the initial gas mixture.

10. The method for separation, purification, and recovery of iodine-125 for production according to claim 9, characterized in that, The separation of helium from the initial gas mixture includes: The adsorption device is connected to the irradiation device, and one end of the circulation pipeline is connected to the downstream outlet of the adsorption device, while the other end is connected to the return inlet of the irradiation device to form a circulation loop. The iodine removal tank is then connected to the circulation loop. The iodine removal tank is cooled down, the circulation pump is started to drive the gas to flow in the circulation loop, the first control valve is closed so that all the gas in the circulation pipeline flows through the iodine removal tank, and the second control valve and the third control valve are opened at the same time. The above-mentioned cycle is maintained for a preset time, and the iodine removal tank causes xenon-124, xenon-125, iodine-125 and iodine-126 in the gas to condense in the iodine removal tank through the freezing effect of the iodine removal tank; When the pressure inside the iodine removal tank is constant, close the third control valve and the circulation pump; The gas storage tank is connected to the iodine removal tank. The vacuum pump is started to pump the helium separated in the circulation loop into the gas storage tank. After the helium is pumped out, the vacuum pump is turned off and the connection between the gas storage tank and the iodine removal tank is cut off, thus completing the separation and storage of helium.

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