Method for separating molybdenum-99 and iodine-131 from nuclear reactor fuel solution that uses uranyl nitrate aqueous solution as fuel

Abstract

A method for separating molybdenum-99 and iodine-131 from a nuclear reactor fuel solution that uses a uranyl nitrate aqueous solution as fuel, comprising the following steps: S1, causing a fuel solution containing fission products to flow through a pretreated extraction column and, after elution and desorption, obtaining a 99Mo and 131I solution, the fuel solution containing the fission products being a uranyl nitrate solution obtained at the end of the operation of a nuclear reactor; S2, causing the 99M and 131I solution obtained in step S1 to flow through a separation column for 99Mo adsorption, a filler material of the separation column being ST-150 resin to which α-benzoin oxime is adsorbed; and S3, an adsorption effluent of the separation column being a 131I crude product, and successively cleaning and desorbing the separation column, so as to obtain a 99Mo crude product.

Description

A method for separating molybdenum-99 and iodine-131 in a nuclear reactor fuel solution using uranyl nitrate aqueous solution as fuel Technical Field

[0001] The present invention relates to the technical field of radionuclide production, and in particular to a method for separating molybdenum-99 and iodine-131 from a nuclear reactor fuel solution using an aqueous uranyl nitrate solution as fuel. Background Art

[0002] Molybdenum-99( 99 Mo) and iodine-131( 131 I) are two important medical radioisotopes. 99 Mohe 131 The traditional production method of I is target irradiation method. Uniform aqueous solution nuclear reactor production 99 Mohe 131 1, the uranyl nitrate (or uranyl sulfate) 235 U is the fuel for the operation of the reactor and also the 99 Mohe 131 The target material of medical radioisotopes such as I is produced without the need for target production. Compared with the target irradiation method, the uniform aqueous solution nuclear reactor production 99 Mohe 131 I has the advantages of high neutron utilization, low waste generation, simple process and low operating cost, and has obvious advantages.

[0003] The prior art is to extract 99 Mohe 131 Method I mainly uses an alumina column to separate and obtain 99 Mohe 131 I. The specific process is: including three alumina columns, the first alumina column is used 99 Mohe 131 The co-extraction of I was repeated on the second alumina column. 99 Mohe 131 The third alumina column can achieve the co-extraction of I, reduce the solution volume, and 99 Mohe 131 Isolation of I. 99 Mohe 131 In the separation of I, alumina is used to adsorb IO3 - , does not adsorb I - The properties of IO3 - Restore to I - , and then passed through the alumina column to achieve 99 Mohe 131 I separation. This process involves 131The conversion of valence state I is relatively complicated. To address this problem, this patent has developed a method with simpler process.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to provide a method for separating molybdenum-99 and iodine-131 from a fuel solution of a nuclear reactor using an aqueous solution of uranyl nitrate as fuel, which can separate and extract molybdenum-99 and iodine-131 from a fuel solution containing a large amount of fission products. 99 Mohe 131 I, and 99 Mohe 131 The recovery rate of I is high.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for separating molybdenum-99 and iodine-131 in a nuclear reactor fuel solution using an aqueous uranyl nitrate solution as fuel comprises the following steps:

[0008] S1, the fuel solution containing fission products flows through the pre-treated extraction column, and after elution and desorption, the 99 Mo, 131 I solution, wherein the fuel solution containing fission products is obtained from the end of operation of a uranyl nitrate solution nuclear reactor;

[0009] S2, the step S1 obtained 99 Mo, 131 I solution flows through the separation column, 99 Mo adsorption, the separation column was filled with ST-150 resin adsorbed with α-benzoin oxime;

[0010] S3, the adsorption effluent of the separation column is 131 I crude product; sequentially cleaning the separation column, desorbing 99 Roughened products.

[0011] The method of precipitating α-benzoin oxime with molybdenum has been widely used in the separation of molybdenum. However, precipitation separation methods suffer from complex operation and difficulty in automation. Column separation methods, on the other hand, offer the advantages of simple operation and automation, making them widely adopted in radiochemical separations. Direct loading of α-benzoin oxime into a column can easily lead to column clogging due to its fine particles. Furthermore, due to the high purity of α-benzoin oxime, Mo desorption is difficult. The present invention organically combines α-benzoin oxime with column separation methods, using a new material in which α-benzoin oxime is adsorbed onto ST-150 resin, which is then loaded into a separation column to separate Mo and I. The ST-150 resin is a resin sphere with a styrene backbone. The ST-150 resin was purchased directly from the Beijing Research Institute of Chemical Metallurgy, a nuclear industry company, and is therefore an existing product. Compared to existing methods that use alumina to separate Mo and I, the present invention does not require an I valence adjustment process and directly and rapidly separates Mo and I, thereby simplifying production steps, improving production efficiency, and significantly increasing the recovery rates of Mo and I. After separation of Mo and I using this method, the recovery rate of Mo is greater than 85%, and the recovery rate of I is greater than 90%. Compared with precipitation methods, the separation of Mo and I can be achieved more simply and rapidly, facilitating the automation process, and can be used in the production of uniform aqueous solution nuclear reactors. 99 Mohe 131 I.

[0012] Furthermore, in step S1, the extraction column is a spherical alumina column.

[0013] Furthermore, in step S2, the filler of the separation column is used to adsorb α-benzoin oxime into the interior of the ST-150 resin using a vacuum impregnation method.

[0014] The specific steps are as follows: α-benzoin oxime is dissolved in an organic phase (ethanol), the prepared organic phase solution is then added to ST-150 resin, and the mixture is shaken at a constant temperature for 4 to 8 hours. The shaken ST-150 resin and the α-benzoin oxime organic phase are placed in a vacuum drying oven and vacuum dried at 40 to 60°C for 6 to 10 hours to obtain ST-150 resin adsorbed with α-benzoin oxime.

[0015] Furthermore, in step S2, the particle size of the filler of the separation column is 80-300 mesh.

[0016] Furthermore, in step S2, the ratio of the height to the diameter of the separation column is 2 to 8.

[0017] Furthermore, in step S2, the separation column is pretreated with a 0.1-1 mol / L nitric acid solution before use.

[0018] Furthermore, in step S3, the separation column is cleaned with 0.01-1.0 mol / L nitric acid solution, water, and 0.001-0.05 mol / L ammonia solution, respectively.

[0019] Furthermore, in step S3, the desorption liquid is 0.2-2.0 mol / L ammonia water or sodium hydroxide solution.

[0020] Furthermore, in step S3, the flow rates of the cleaning liquid and the desorption liquid are both 0.1 to 5.0 ml / ml column packing / min.

[0021] Furthermore, in step S3, the flow rates of the cleaning solution and the desorption solution are both 0.5-1.5 ml / ml column packing / min.

[0022] The flow rates of the cleaning and desorption liquids affect the desorption rate of Mo, and thus the recovery rate of Mo adsorbed by α-benzoin oxime. Experiments have shown that when the flow rates of both the cleaning and desorption liquids are 0.1-5.0 ml / ml column packing / min, the Mo recovery rate is over 80%. When the flow rates of both the cleaning and desorption liquids are 0.5-1.5 ml / ml column packing / min, the Mo recovery rate is over 90%.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] The present invention adopts styrene skeleton resin adsorbed with α-benzoin oxime as the filler of the separation column, which can not only separate and extract a large amount of fission products from the fuel solution, but also can separate and extract the fission products from the fuel solution. 99 Mohe 131 I, and 99 Mohe 131 The recovery rate of I is high, and the recovery rate of Mo can reach more than 90%, which can be used in solution reactors 99 Mohe 131 The ST-150 resin, which is adsorbed with α-benzoin oxime, is easily synthesized. The resulting resin forms small, uniformly sized spheres, resulting in a fast flow rate after column loading and less prone to clogging. The synthesized resin has a high adsorption capacity for Mo, facilitating its adsorption. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with examples. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0026] Example 1:

[0027] A method for separating molybdenum-99 and iodine-131 in a nuclear reactor fuel solution using an aqueous uranyl nitrate solution as fuel comprises the following steps:

[0028] S1, the fuel solution containing fission products flows through the pre-treated spherical alumina column, and after elution and desorption, obtain 99 Mo, 131 I solution, wherein the fuel solution containing fission products is obtained from the end of operation of a uranyl nitrate solution nuclear reactor;

[0029] Pretreatment process: Calcinate spherical alumina in a muffle furnace at 500-650°C for 4-8 hours to obtain activated alumina. Then soak it in 0.01-1.0 mol / L nitric acid solution for 24 hours, wet load it onto a chromatography column, and then equilibrate the column with 2-10 column volumes of water and 2-10 column volumes of 0.01-1.0 mol / L nitric acid solution.

[0030] The fuel simulation solution flows through the alumina column, and Mo and I are adsorbed on the extraction column. The adsorption effluent is the fuel simulation solution. Then, the extraction column is eluted with 2 to 10 column volumes of 0.01 to 1.0 mol / L nitric acid solution, 2 to 10 column volumes of deionized water, and finally, the extraction column is desorbed with 2 to 10 column volumes of 0.1 to 3 mol / L ammonia solution to obtain 99 Mo, 131 I solution.

[0031] S2, the step S1 obtained 99 Mo, 131 I solution adjusts the acidity of the solution to 0.1~1mol / L system, flows through the separation column, and the effluent of the separation column is 131 I; The separation column was pretreated with 0.1-1 mol / L nitric acid solution before use. 99 Mo adsorption, the filler of the separation column is ST-150 resin adsorbed with αα-benzoin oxime, specifically, the filler of the separation column uses a vacuum impregnation method to adsorb α-benzoin oxime into the interior of the ST-150 resin;

[0032] The particle size of the separation column filler is 80 to 120 meshes; the ratio of the height to the diameter of the separation column is 2 to 8. 99 Mo, 131 I solution, after passing through the separation column, 99 Mo adsorption, the effluent of the separation column is 131 I solution, that is 131 I crude product.

[0033] S3, sequentially clean and desorb the separation column to obtain 99 Rough products;

[0034] Specifically, the separation column is eluted with 2 to 10 column volumes of 0.01 to 1.0 mol / L nitric acid solution, 2 to 10 column volumes of water, and 2 to 10 column volumes of 0.001 to 0.05 mol / L ammonia solution at a flow rate of 0.1 to 5.0 mL / mL column filler / min, and after the elution is completed, the separation column is desorbed with 2 to 10 column volumes of 0.2 to 3.0 mol / L ammonia solution to obtain a crude Mo product.

[0035] In order to verify the separation effect of the method described in this embodiment, the following experiments were performed:

[0036] Preparation of ST-150 resin adsorbed with α-benzoin oxime:

[0037] Dissolve 1g of α-benzoin oxime in 10mL of ethanol. Add the resulting organic phase solution to 4g of 100-mesh ST-150 resin pellets and shake at a constant temperature for 6 hours. Place the shaken ST-150 resin and α-benzoin oxime organic phase in a vacuum drying oven at 60°C for 8 hours to obtain the ST-150 resin adsorbed with α-benzoin oxime.

[0038] Example 2:

[0039] The recovery rates of Mo and I were verified when α-benzoin oxime was adsorbed on ST-150 resin as the separation column filler.

[0040] 1 g of ST-150 resin material adsorbed with α-benzoin oxime was weighed, with a particle size of 80-300 mesh. The material was wet-loaded into a 10 mm x 200 mm separation column, using the same filler particles and aspect ratio as in Example 1. The separation column was pretreated by rinsing with 10 mL of deionized water and 10 mL of 0.2 mol / L nitric acid solution. Then, 0.5 mL of a 20 mg / L solution of Mo and I containing 0.2 mol / L nitric acid was added to the column for adsorption for half an hour. After adsorption, the column was rinsed with 35 mL of 0.2 mol / L nitric acid solution at a flow rate of 1 mL / min. After rinsing with 35 mL of deionized water, the column was desorbed with 1 mol / L ammonia solution at room temperature.

[0041] The content of I in the nitric acid eluent of the separation column was measured, and the content of Mo in the ammonia desorption liquid of the separation column was measured. The calculated recovery rates of Mo were 90.5%, and the recovery rates of I were 95.3%.

[0042] Example 3:

[0043] Verify the effect of flow rate on Mo adsorption recovery.

[0044] 1 g of ST-150 resin material adsorbed with α-benzoin oxime was weighed and loaded onto a column. After pre-rinsing, the separation column had the same filler particles and aspect ratio as in Example 1. 20 mg / L of platinum and iodine were added, and 0.5 mL of a 0.2 mol / L nitric acid solution was applied to the column for adsorption for half an hour. After adsorption, the column was rinsed with 35 mL of 0.2 mol / L nitric acid solution. After rinsing, the α-benzoin oxime column was rinsed with 35 mL of deionized water and then desorbed with 40 mL of 1 mol / L ammonia solution. During the above process, the column flow rate (overall flow rate) was adjusted to 0.5 mL / min, 1.0 mL / min, 1.5 mL / min, and 2.0 mL / min, respectively, and the process was carried out at room temperature.

[0045] Based on the sample measurement data, the adsorption rate, desorption rate and recovery rate of Mo on the ST-150 resin column adsorbed with α-benzoin oxime at different flow rates were calculated. The results are shown in Table 1.

[0046] Table 1 Mo adsorption recovery rate at different flow rates

[0047] As shown in Table 1, the adsorption rate of Mo on the ST-150 column adsorbing α-benzoin oxime remained essentially unchanged as the flow rate changed. However, the desorption rate of Mo on the ST-150 resin column adsorbing α-benzoin oxime decreased significantly as the flow rate increased.

[0048] Example 4:

[0049] The effects of impurities such as Ce, Sr, and Te on the adsorption of Mo by ST-150 resin column adsorbed with α-benzoin oxime were verified.

[0050] Prepare a mixed solution containing 10 mg / L Ce, Sr, and Te, 20 mg / L Li, and Mo in a 0.2 mol / L nitric acid system. Weigh 1 g of ST-150 resin material adsorbed with α-benzoin oxime and pre-wash the column. The separation column's filler particles and aspect ratio are the same as in Example 1. Pipette 0.5 mL of the simulated solution onto the column for adsorption for half an hour. Rinse the column with 35 mL of a 0.2 mol / L HNO3 solution. After rinsing, rinse the column with 5 mL of deionized water and then with 40 mL of 1 mol / L ammonia for desorption. The flow rate for this process is 1 mL / min and the process is performed at room temperature.

[0051] Based on sample measurement data, the adsorption rate of Mo on the ST-150 resin column for α-benzoin oxime was calculated to be 97.8%, the desorption rate was 96.4%, and the recovery rate was 94.3%. The adsorption rate of Mo on the ST-150 resin column without impurities was 98.9%, the desorption rate was 95.6%, and the recovery rate was 94.6%. Therefore, impurities such as Ce, Sr, and Te have no effect on the adsorption of Mo on the ST-150 resin column for α-benzoin oxime.

[0052] Example 5:

[0053] The adsorption effects of ST-150 resin adsorbed with α-benzoin oxime and synthetic resins containing α-benzoin oxime prepared by other methods were compared.

[0054] The preparation method of the synthetic resin containing α-benzoin oxime is as follows:

[0055] 1) Prepare a dispersant solution: Add 0.8 g of dispersant (polyvinyl alcohol) to 50 mL of deionized water while stirring, and heat to 50° C. to completely dissolve the dispersant to obtain a dispersant solution;

[0056] 2) preparing an organic phase containing α-benzoin oxime: adding 1 g of α-benzoin oxime to 25 mL of a mixture of acetone and chloroform (volume ratio of 2:1) as an organic solvent, stirring to dissolve the α-benzoin oxime, then adding 0.1 g of a tackifier, polystyrene, and ultrasonically dispersing the mixture for 30-40 minutes to obtain an organic phase containing α-benzoin oxime;

[0057] 3) Preparation of styrene-divinylbenzene prepolymer: 40 g of styrene, 10 g of divinylbenzene and 2 g of initiator (dibenzoyl peroxide) were mixed and stirred uniformly. The mixture was heated to 65-70° C. and prepolymerized for 30-40 minutes to obtain a styrene-divinylbenzene prepolymer.

[0058] 4) Synthetic resin: 50 mL of the styrene-divinylbenzene prepolymer obtained in step (3) is added to 50 mL of the dispersant solution obtained in step (1), stirred to disperse it into beads, and slowly heated to 70°C; 25 mL of the organic phase containing α-benzoin oxime obtained in step (2) is added to the resulting mixture, and the temperature is continued to be raised to 85°C. The mixture is reacted at this temperature for 10 hours, and the heating is stopped and the temperature is naturally cooled; when the temperature drops to 50°C, the reaction mixture is filtered, the precipitate is washed with water, and naturally dried to obtain a synthetic resin containing α-benzoin oxime.

[0059] The preparation method for the synthetic resin containing α-benzoin oxime described above involves complex synthesis steps and conditions. The resulting resin has a wide particle size distribution, and screening for the desired particle size results in a low product recovery rate. The ST-150 resin synthesized in this embodiment, which adsorbs α-benzoin oxime, has controllable resin size, a simple synthesis method, and easily controlled synthesis conditions. The yield of the synthesized product exceeds 85%. Test results indicate that the resin prepared in this invention has a saturated Mo adsorption capacity of 83 to 105 mg / g, significantly increasing its Mo adsorption capacity and possessing significant application value.

[0060] Prepare a mixed solution containing 10 mg / L Ce, Sr, and Te, 20 mg / L Li, and Mo in a 0.2 mol / L nitric acid system. Weigh 1 g of ST-150 resin adsorbed with α-benzoin oxime (separation column 1) and 1 g of a synthetic resin containing α-benzoin oxime (separation column 2) and load the columns. After pre-rinsing, the separation columns' filler particles and aspect ratios are the same as in Example 1. Transfer 2 mL of the simulated solution onto the column for adsorption for half an hour. Rinse the column with 35 mL of a 0.2 mol / L HNO solution. After rinsing, rinse the column with 5 mL of deionized water and then with 40 mL of 1 mol / L ammonia for desorption. This process is performed at a flow rate of 1 mL / min at room temperature.

[0061] The I content in the nitric acid eluent of the separation column and the Mo content in the ammonia desorption solution of the separation column were measured. The calculated Mo recovery rates for separation column 1 were 88.9% and 96.4% for I. The Mo recovery rates for separation column 2 were 46.7% and 95.6% for I.

[0062] Neither resin adsorbs iodine, resulting in iodine recovery rates exceeding 90% in the nitric acid eluent. However, separation column 2 has a lower adsorption capacity for Mo; even with the same mass of adsorbent material, its adsorption efficiency is far inferior to that of separation column 1. Therefore, the ST-150 resin, which adsorbs α-benzoin oxime, has a higher Mo adsorption capacity and can efficiently achieve Mo adsorption and separation.

[0063] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method 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 in the scope of protection of the present invention.

Claims

1. A method for separating molybdenum-99 and iodine-131 from the fuel solution of a nuclear reactor using an aqueous solution of uranyl nitrate as fuel, characterized in that, it comprises the following steps: S1. Flow the fuel solution containing fission products through the pretreated extraction column. After elution and desorption, obtain 99 Mo 131 I solution. Among them, the fuel solution containing fission products is obtained from the spent nuclear uranium nitrate solution after the operation of the nuclear reactor ends; S2. Flow the 99 Mo, 131 I solution through a separation column for 99 Mo adsorption. The packing material of the separation column is ST-150 resin adsorbed with α-benzoin oxime; S3. The adsorption effluent of the separation column is 131 I crude product; the separation column is successively cleaned and desorbed to obtain 99 crude Mo product.

2. The method for separating molybdenum-99 and iodine-131 from the fuel solution of a nuclear reactor using an aqueous solution of uranyl nitrate as fuel according to claim 1, characterized in that, in step S1, the extraction column is a spherical alumina column.

3. The method for separating molybdenum-99 and iodine-131 from the fuel solution of a nuclear reactor using an aqueous solution of uranyl nitrate as fuel according to claim 1, characterized in that, in step S2, the packing of the separation column adsorbs α-benzoin oxime into the interior of ST-150 resin by the vacuum impregnation method.

4. The method for separating molybdenum-99 and iodine-131 from the fuel solution of a nuclear reactor using an aqueous solution of uranyl nitrate as fuel according to claim 1, characterized in that, in step S2, the particle size of the packing of the separation column is 80 - 300 mesh.

5. The method for separating molybdenum-99 and iodine-131 from the fuel solution of a nuclear reactor using an aqueous solution of uranyl nitrate as fuel according to claim 1, characterized in that, in step S2, the ratio of the height to the diameter of the separation column is 2 - 8.

6. The method for separating molybdenum-99 and iodine-131 from the fuel solution of a nuclear reactor using an aqueous solution of uranyl nitrate as fuel according to claim 1, characterized in that, in step S2, the separation column is pretreated with a nitric acid solution of 0.1 - 1 mol / L before use.

7. The method for separating molybdenum-99 and iodine-131 from the fuel solution of a nuclear reactor using an aqueous solution of uranyl nitrate as fuel according to claim 1, characterized in that, in step S3, the separation column is washed with a 0.01 - 1.0 mol / L nitric acid solution, water, and a 0.001 - 0.05 mol / L ammonia water solution respectively.

8. The method for separating molybdenum-99 and iodine-131 from the fuel solution of a nuclear reactor using an aqueous solution of uranyl nitrate as fuel according to claim 1, characterized in that, in step S3, the desorbing solution is a 0.2 - 2.0 mol / L ammonia water or sodium hydroxide solution.

9. The method for separating molybdenum-99 and iodine-131 from the fuel solution of a nuclear reactor using an aqueous solution of uranyl nitrate as fuel according to claim 1, characterized in that, in step S3, the flow rates of the washing solution and the desorbing solution are both 0.1 - 5.0 ml / ml column packing / min.

10. The method for separating molybdenum-99 and iodine-131 from the fuel solution of a nuclear reactor using an aqueous solution of uranyl nitrate as fuel according to claim 9, characterized in that, in step S3, the flow rates of the washing solution and the desorbing solution are both 0.5 - 1.5 ml / ml column packing / min.

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