A method for the production of iodine-131 by a reactor using a uranyl nitrate solution as a nuclear fuel
By combining reduction with reducing agents and distillation with alkaline solution absorption, the problem of high impurity content in crude iodine-131 extracted from solutions was solved, achieving efficient purification and high recovery rate of sodium iodide solution production, meeting medical requirements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NUCLEAR POWER INSTITUTE OF CHINA
- Filing Date
- 2023-12-29
- Publication Date
- 2026-07-07
AI Technical Summary
The crude iodine-131 product extracted from the solution heap in the existing technology contains some fission product impurities, which cannot meet the requirements of medical technical indicators and requires further purification.
Sodium iodo-131 is reduced to elemental iodine-131 using a reducing agent. Iodine-131 vapor is obtained by distillation and absorbed by an alkaline solution to prepare an iodide solution that meets medical requirements. Quartz or polytetrafluoroethylene containers and multi-stage absorption bottles are used in the process to increase the contact area between the gas and the alkaline solution.
It achieves efficient removal of radioactive impurities from iodine-131, with an iodine recovery rate of over 90%, meeting medical requirements and reducing purification time and cost.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of radioactive isotope production, specifically to a purification method for producing iodine-131 in a reactor using uranyl nitrate solution as nuclear fuel. Background Technology
[0002] Iodine-131 is an important medical radionuclide and the earliest and most widely used therapeutic radionuclide in nuclear medicine. Iodine-131 is a globally recognized effective treatment for hyperthyroidism and thyroid cancer. In addition, the use of iodine-131-labeled monoclonal antibodies for tumor treatment, which has been gradually developed in recent years, has further promoted the application of iodine-131. Therefore, the market demand for iodine-131 is gradually increasing.
[0003] Iodine-131 is typically produced using either neutron activation or a uranium-235 solid target method. However, both methods are small-scale, generate significant amounts of radioactive waste, and are costly. Producing iodine-131 using a homogeneous nuclear reactor (hereinafter referred to as a solution reactor) fueled by uranyl nitrate solution allows for large-scale production. For example, operating such a reactor at 200 kW for 24 hours can generate approximately 400 Ci of iodine-131. This method produces less waste, has lower costs, and is therefore of significant potential for widespread adoption.
[0004] The solution reactor generates a large number of fission products during operation, including the medical radioactive isotopes molybdenum-99 and iodine-131. After extracting iodine-131 from the fuel solution, the crude iodine-131 product still contains some fission product impurities and does not meet the technical requirements for medical sodium iodide solution products. Therefore, it is necessary to take measures to further purify the crude iodine-131 product extracted from the solution reactor. Summary of the Invention
[0005] This invention addresses the problem that the content of iodine-131 impurities extracted from solution heaps does not meet the requirements of medical technical indicators, and provides a simple, efficient, and low-product-loss method for iodine-131 purification.
[0006] The purpose of this invention is to provide a purification method for producing iodine-131 from a solution pile, comprising:
[0007] Adding a reducing agent to the iodine-131 product solution reduces sodium iodo-131 to elemental iodine-131;
[0008] Iodine-131 was distilled to obtain iodine-131 vapor;
[0009] Iodine-131 vapor is absorbed by an alkaline solution to obtain a sodium iodide solution.
[0010] As one possible design, the reducing agent includes at least one of sodium sulfite, sulfurous acid, sodium thiosulfate, and ferrous sulfate.
[0011] As one possible design, the concentration of the reducing agent is 10 g / L to 100 g / L.
[0012] As one possible design, the distillation pressure is atmospheric pressure, and the distillation temperature is 60°C to 100°C.
[0013] As one possible design, the alkaline solution includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, and ammonia.
[0014] As one possible design, the concentration of the alkaline solution is 0.1 mol / L to 2.0 mol / L.
[0015] As one possible design, the inlet pipe of the alkaline solution absorption bottle is provided with a sand core at the end, and the pore size of the sand core is 10μm~5000μm.
[0016] As one possible design, the alkaline solution absorbs iodine-131 vapor using at least three stages of absorption.
[0017] As one possible design, the sand core is installed at the end of the air inlet pipe of each alkaline solution absorption bottle, and the sand core hole diameter at the end of the air inlet pipe of the subsequent absorption bottle is larger than that at the end of the air inlet pipe of the previous absorption bottle.
[0018] As one possible design, the distillation process is carried out in a container made of quartz or polytetrafluoroethylene.
[0019] The beneficial effects of this invention are as follows:
[0020] The purification method disclosed in this invention can effectively remove radioactive impurities from iodine-131 extracted from the solution pile, and can obtain a sodium iodide solution product that meets medical requirements, thus realizing the production of medical sodium iodide solution.
[0021] The purification method disclosed in this invention is simple and can effectively remove impurities from iodine-131 nuclide, making it meet medical requirements. The average iodine recovery rate can reach more than 90%. Detailed Implementation
[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.
[0023] Iodine-131 is typically produced using neutron activation or uranium-235 solid target methods, but these methods are small-scale, generate significant amounts of radioactive waste, and are costly. Producing iodine-131 using a solution reactor allows for large-scale production. For example, a reactor operating at 200 kW for 24 hours can generate approximately 400 Ci of iodine-131. This method produces less waste, is less expensive, and has significant potential for widespread adoption. Solution reactors generate a large amount of fission products during operation, including the medical radioactive isotopes molybdenum-99 and iodine-131. After extracting iodine-131 from the fuel solution, the crude iodine-131 product still contains some fission product impurities, which do not meet medical requirements. Therefore, the crude sodium iodide product needs to be purified to reduce the content of radioactive impurities, thereby obtaining a sodium iodide product that meets medical requirements.
[0024] Analysis of the crude iodine-131 product revealed the presence of molybdenum-99 in addition to the main component, iodine-131. This invention reduces iodine-131 to elemental iodine, and then utilizes the sublimation property of elemental iodine to recover it. The key steps include: reducing iodine in sodium iodate to elemental iodine with a reducing agent; distilling to evaporate the elemental iodine into iodine vapor; and absorbing the iodine vapor with an alkaline solution to obtain an iodide that meets medical requirements.
[0025] This invention discloses a purification method for producing iodine-131 from a solution heap, comprising the following steps:
[0026] S1. Add a reducing agent to the crude iodine-131 product solution to reduce sodium iodo-131 to elemental iodine-131;
[0027] Commonly used reducing agents in this step include, but are not limited to, sodium sulfite, sulfurous acid, sodium thiosulfate, and ferrous sulfate. The concentration of the reducing agent is generally 10 g / L to 100 g / L. The amount of reducing agent added is determined by the content of sodium iodide-131 in the crude iodine-131 product.
[0028] S2. Iodine-131 is distilled to obtain iodine-131 vapor;
[0029] Distillation in this step is generally carried out under normal pressure. The equipment used in the distillation process must be non-adsorbent of iodine, such as quartz vessels (details not elaborated here). The distillation temperature is generally 60℃~100℃, preferably 80℃~100℃, and more preferably 90℃~100℃. The main purpose of the distillation process is to evaporate elemental iodine-131, facilitating subsequent iodine recovery.
[0030] S3. Iodine-131 vapor is absorbed using an alkaline solution to obtain sodium iodide solution.
[0031] Iodine-131 reacts with water to form an acidic solution, which then reacts with an alkaline solution to produce an iodide solution that meets medical requirements.
[0032] The alkaline solutions used in this step include, but are not limited to, sodium hydroxide, potassium hydroxide, sodium carbonate, and ammonia. The concentration of the alkaline solution is generally 0.1 mol / L to 2.0 mol / L. The amount of alkaline solution used is selected based on the mass of iodine-131 to be absorbed.
[0033] The absorption process of an alkaline solution can be described as follows:
[0034] The alkaline solution is placed in a series of absorption bottles. A sand core can be installed at the end of the inlet pipe of each absorption bottle to increase the contact area between iodine vapor and the alkaline absorption solution, thereby improving the recovery rate of iodine-131. The number of absorption bottles is selected according to the absorption requirements, but generally no less than three.
[0035] In order to reduce the resistance in the alkaline absorption process, in this invention, the particle size of the sand core in the subsequent absorption bottle through which the gas passes is larger than that in the previous absorption bottle.
[0036] This purification method can effectively purify iodine-131 extracted from a solution heap, producing a sodium iodide solution product that meets medical technical requirements.
[0037] When obtaining a sodium iodide-131 solution product that meets the requirements of medical technical specifications, the purification method disclosed in this invention can also save purification time and purification costs.
[0038] The composition of the crude iodine-131 product used in the following examples is shown in Table 1.
[0039] Example 1: This example provides a purification method for producing iodine-131 using a solution pile. The specific implementation steps are as follows:
[0040] (1) Sodium sulfite is used as a reducing agent to reduce the crude iodine-131 product extracted from the fuel solution to sodium iodide-131. The concentration of the sodium sulfite solution used is 100 g / L.
[0041] (2) Iodine-131 is distilled from sodium iodide solution using conventional distillation method to generate iodine-131 vapor. The distillation temperature is 60°C and the distillation container is made of quartz glass.
[0042] (3) Iodine-131 vapor is absorbed by sodium hydroxide to purify iodine-131. The concentration of the sodium hydroxide solution is 1.0 mol / L. A sand core is provided at the end of the gas inlet tube of the alkaline solution absorption bottle. The alkaline solution absorption bottle is set as a three-stage absorption bottle, and the pore size of the sand core of the absorption bottle increases step by step, namely 10 μm, 100 μm and 500 μm.
[0043] The iodine-131 purified using this example had a recovery rate of 92.3%, and the impurity concentration met the requirements for medical technical specifications. The results are shown in Table 1.
[0044] Example 2: This example provides a purification method for producing iodine-131 from a solution pile. The specific implementation steps are as follows:
[0045] (1) Sodium sulfite is used as a reducing agent to reduce the crude iodine-131 product extracted from the fuel solution to sodium iodide-131. The concentration of the sodium sulfite solution used is 10 g / L.
[0046] (2) Iodine-131 is distilled from sodium iodide solution using conventional distillation method to generate iodine-131 vapor. The distillation temperature is 60°C and the distillation container is made of quartz glass.
[0047] (3) Iodine-131 vapor is absorbed by sodium hydroxide to purify iodine-131. The concentration of the sodium hydroxide solution is 0.1 mol / L. A sand core is provided at the end of the gas inlet tube of the alkaline solution absorption bottle. The alkaline solution absorption bottle is set as a three-stage absorption bottle, and the pore size of the sand core of the absorption bottle increases step by step, namely 10 μm, 100 μm and 500 μm.
[0048] The iodine-131 purified using this example had a recovery rate of 91.6%, and the impurity concentration met the requirements for medical technical specifications. The results are shown in Table 1.
[0049] Example 3: This example provides a purification method for producing iodine-131 using a solution pile. The specific implementation steps are as follows:
[0050] (1) Sodium sulfite is used as a reducing agent to reduce the crude iodine-131 product extracted from the fuel solution to sodium iodide-131. The concentration of the sodium sulfite solution used is 30 g / L.
[0051] (2) Iodine-131 is distilled from sodium iodide solution using conventional distillation method to generate iodine-131 vapor. The distillation temperature is 60°C and the distillation container is made of quartz glass.
[0052] (3) Iodine-131 vapor is absorbed by sodium hydroxide to purify iodine-131. The concentration of the sodium hydroxide solution is 0.5 mol / L. A sand core is provided at the end of the gas inlet tube of the alkaline solution absorption bottle. The alkaline solution absorption bottle is set as a three-stage absorption bottle, and the pore size of the sand core of the absorption bottle increases step by step, namely 10 μm, 100 μm and 500 μm.
[0053] The iodine-131 purified using this example had a recovery rate of 91.4%, and the impurity concentration met the requirements for medical technical specifications. The results are shown in Table 1.
[0054] Example 4: This example provides a purification method for producing iodine-131 using a solution pile. The specific implementation steps are as follows:
[0055] (1) Sodium thiosulfate is used as a reducing agent to reduce the crude iodine-131 product extracted from the fuel solution to sodium iodide-131. The concentration of the sodium thiosulfate solution used is 50 g / L.
[0056] (2) Iodine-131 is distilled from sodium iodide solution using conventional distillation method to generate iodine-131 vapor. The distillation temperature is 90℃ and the distillation container is made of quartz glass.
[0057] (3) Iodine-131 vapor is absorbed by ammonia water to purify iodine-131. The concentration of the ammonia water solution is 1.8 mol / L. A sand core is provided at the end of the air inlet tube of the alkaline solution absorption bottle. The alkaline solution absorption bottle is set as a three-stage absorption bottle, and the pore size of the sand core of the absorption bottle increases step by step, namely 10 μm, 100 μm and 500 μm.
[0058] The iodine-131 purified using this example had a recovery rate of 92.1%, and the impurity concentration met the requirements for medical technical specifications. The results are shown in Table 1.
[0059] Example 5: This example provides a purification method for producing iodine-131 using a solution pile. The specific implementation steps are as follows:
[0060] (1) Ferrous sulfate is used as a reducing agent to reduce the crude iodine-131 product extracted from the fuel solution to sodium iodide-131. The concentration of the ferrous sulfate solution used is 80 g / L.
[0061] (2) Iodine-131 is distilled from sodium iodide solution using conventional distillation method to generate iodine-131 vapor. The distillation temperature is 100℃ and the distillation container is made of quartz glass.
[0062] (3) Iodine-131 vapor is absorbed by potassium hydroxide to purify iodine-131. The concentration of the potassium hydroxide solution is 0.8 mol / L. A sand core is provided at the end of the gas inlet tube of the alkaline solution absorption bottle. The alkaline solution absorption bottle is set as a three-stage absorption bottle, and the pore size of the sand core of the absorption bottle increases step by step, namely 10 μm, 100 μm and 500 μm.
[0063] The iodine-131 purified using this example had a recovery rate of 91.8%, and the impurity concentration met the requirements for medical technical specifications. The results are shown in Table 1.
[0064] Example 6: This example provides a purification method for producing iodine-131 using a solution pile. The specific implementation steps are as follows:
[0065] (1) Using sulfurous acid as a reducing agent, the crude iodine-131 product extracted from the fuel solution is reduced to sodium iodide-131. The concentration of the sulfurous acid solution used is 80 g / L.
[0066] (2) Iodine-131 is distilled from sodium iodide solution using conventional distillation method to generate iodine-131 vapor. The distillation temperature is 70°C and the distillation container is made of quartz glass.
[0067] (3) Iodine-131 vapor is absorbed by ammonia water to achieve the purification of iodine-131. The concentration of the ammonia water solution is 1.5 mol / L. A sand core is provided at the end of the air inlet tube of the alkaline solution absorption bottle. The alkaline solution absorption bottle is set as a three-stage absorption bottle, and the pore size of the sand core of the absorption bottle increases step by step, namely 10 μm, 100 μm and 500 μm.
[0068] The iodine-131 purified using this example had a recovery rate of 92.5%, and the impurity concentration met the requirements for medical technical specifications. The results are shown in Table 1.
[0069] Example 7: This example provides a purification method for producing iodine-131 using a solution pile. The specific implementation steps are as follows:
[0070] (1) Using sulfurous acid as a reducing agent, the crude iodine-131 product extracted from the fuel solution is reduced to sodium iodide-131. The concentration of the sulfurous acid solution used is 20 g / L.
[0071] (2) Iodine-131 is distilled from sodium iodide solution using conventional distillation method to generate iodine-131 vapor. The distillation temperature is 86℃ and the distillation container is made of quartz glass.
[0072] (3) Iodine-131 vapor is absorbed by sodium hydroxide to purify iodine-131. The concentration of the sodium hydroxide solution is 2.0 mol / L. A sand core is provided at the end of the gas inlet tube of the alkaline solution absorption bottle. The alkaline solution absorption bottle is set as a four-stage absorption bottle, and the pore size of the sand core of the absorption bottle increases step by step, namely 10 μm, 200 μm, 1000 μm and 5000 μm.
[0073] The iodine-131 purified using this example had a recovery rate of 91.3%, and the impurity concentration met the requirements for medical technical specifications. The results are shown in Table 1.
[0074] Example 8: This example provides a purification method for producing iodine-131 using a solution pile. The specific implementation steps are as follows:
[0075] (1) Sodium thiosulfate is used as a reducing agent to reduce the crude iodine-131 product extracted from the fuel solution to sodium iodide-131. The concentration of the sodium thiosulfate solution used is 10 g / L.
[0076] (2) Iodine-131 is distilled from sodium iodide solution using conventional distillation method to generate iodine-131 vapor. The distillation temperature is 65°C and the distillation container is made of quartz glass.
[0077] (3) Iodine-131 vapor is absorbed by potassium hydroxide to purify iodine-131. The concentration of the potassium hydroxide solution is 0.7 mol / L. A sand core is provided at the end of the gas inlet tube of the alkaline solution absorption bottle. The alkaline solution absorption bottle is set as a four-stage absorption bottle, and the pore size of the sand core of the absorption bottle increases step by step, namely 10 μm, 200 μm, 1000 μm and 5000 μm.
[0078] The iodine-131 purified using this example had a recovery rate of 91.6%, and the impurity concentration met the requirements for medical technical specifications. The results are shown in Table 1.
[0079] Example 9: This example provides a purification method for producing iodine-131 using a solution pile. The specific implementation steps are as follows:
[0080] (1) Sodium thiosulfate is used as a reducing agent to reduce the crude iodine-131 product extracted from the fuel solution to sodium iodide-131. The concentration of the sodium thiosulfate solution used is 80 g / L.
[0081] (2) Iodine-131 is distilled from sodium iodide solution using conventional distillation method to generate iodine-131 vapor. The distillation temperature is 96℃ and the distillation container is made of quartz glass.
[0082] (3) Iodine-131 vapor is absorbed by potassium hydroxide to purify iodine-131. The concentration of the potassium hydroxide solution is 2.0 mol / L. A sand core is provided at the end of the gas inlet tube of the alkaline solution absorption bottle. The alkaline solution absorption bottle is set as a four-stage absorption bottle, and the pore size of the sand core of the absorption bottle increases step by step, namely 10 μm, 200 μm, 1000 μm and 5000 μm.
[0083] The iodine-131 purified using this example had a recovery rate of 92.8%, and the impurity concentration met the requirements for medical technical specifications. The results are shown in Table 1.
[0084] As demonstrated in Examples 1-9, the purification method for producing iodine-131 using the solution-pile production method disclosed in this invention achieves a high recovery rate of iodine-131 radionuclide (i.e., minimal waste), thus avoiding significant waste. The recovered product contains few impurities, meeting medical requirements.
[0085] In Examples 1-4, the intake pipe is made of quartz, while in Examples 5-9, the intake pipe is made of tetrafluoroethylene.
[0086] Comparative Example 1
[0087] Unlike Example 1, the intake pipe in this comparative example is made of latex tubing.
[0088] The recovery rate of iodine-131 obtained by comparative purification was 40.3%.
[0089] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A purification method for producing iodine-131 in a reactor using uranyl nitrate solution as nuclear fuel, characterized in that, The purification method includes: A reducing agent is added to the crude iodine-131 product to reduce sodium iodo-131 to elemental iodine-131; Iodine-131 was distilled to obtain iodine-131 vapor; Iodine-131 vapor is absorbed by an alkaline solution to obtain sodium iodide solution product. The reducing agent includes at least one of sodium sulfite, sulfurous acid, sodium thiosulfate, and ferrous sulfate. The concentration of the reducing agent is 10 g / L to 100 g / L; The distillation temperature is 60℃~100℃; The alkaline solution includes at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, and ammonia water; The concentration of the alkaline solution is 0.1 mol / L to 2.0 mol / L.
2. The purification method according to claim 1, characterized in that, The distillation pressure is atmospheric pressure.
3. The purification method according to claim 1, characterized in that, The inlet tube of the alkaline solution absorption bottle for absorbing iodine-131 vapor is made of quartz or polytetrafluoroethylene, and a sand core is installed at the end of the inlet tube with a pore size of 10μm~5000μm.
4. The purification method according to claim 1, characterized in that, The alkaline solution absorbs iodine-131 vapor using at least three stages of absorption.
5. The purification method according to claim 4, characterized in that, The sand core installed at the end of the air inlet pipe of each alkaline solution absorption bottle has a larger hole diameter at the end of the air inlet pipe of the next absorption bottle than at the end of the air inlet pipe of the previous absorption bottle.
6. The purification method according to claim 1, characterized in that, The distillation process is carried out in a container made of quartz or polytetrafluoroethylene.