A simulation experiment method for organic iodine generated in a spent fuel reprocessing process

Abstract

The application provides a simulation experiment method for organic iodine generated in a spent fuel reprocessing process, and belongs to the technical field of spent fuel reprocessing. The method uses gamma ray irradiation to simulate a strong irradiation environment, induces organic iodine conversion reaction in a simulation solution, and based on this, a product extraction method is provided. The method not only realizes qualitative and quantitative analysis of organic iodine, obtains the organic iodine conversion ability of different organic reagents and different iodine compounds, but also realizes identification of intermediate products of the reaction. In the application, irradiation products are comprehensively obtained, reasoning of the organic iodine conversion mechanism is assisted, an analysis method is established to identify reaction products, and finally, the organic iodine conversion reaction mechanism is reasoned according to the structure characteristics of the products.

Description

Technical Field

[0001] This invention belongs to the field of spent fuel reprocessing technology, specifically relating to a simulation experimental method for the generation of organic iodine in a spent fuel reprocessing process. Background Technology

[0002] Sustainable development of nuclear energy depends on the safe management and efficient reprocessing of spent fuel, including radioactive nuclides. 129 I, as a nuclear fission product, is a key element requiring strict control during reprocessing due to its long half-life and high biotoxicity. In water-based spent fuel reprocessing processes, some... 129 I- is converted into organic iodine, primarily during the separation and purification stage, with a smaller portion occurring in the head-end dissolution phase. Organic iodine is highly volatile and toxic, posing a risk of leakage. Furthermore, it readily enters the organic phase during separation and purification, causing radiation damage to the organic extractant, affecting its reuse efficiency and the purity of the final uranium-plutonium product. Therefore, clarifying the conversion mechanism of organic iodine in spent fuel reprocessing is crucial for optimizing process parameters, suppressing organic iodine formation, and ensuring the safe management of radioactive iodine.

[0003] Existing research on organoiodine formation primarily focuses on severe nuclear accident scenarios, where reaction conditions differ significantly from spent fuel reprocessing processes, including the initial chemical form of iodine, solution medium, and organic phase composition. Furthermore, current studies largely concentrate on the overall conversion rate of organoiodine, lacking a systematic elucidation of its molecular-level conversion mechanisms. Currently, there is a lack of experimental and analytical methods capable of simulating reprocessing conditions and systematically analyzing the formation behavior and conversion mechanisms of organoiodine under different initial forms of iodine and the influence of organic reagents. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a simulation experimental method for the generation of organic iodine in spent fuel reprocessing. This invention utilizes Co-60 gamma ray irradiation to simulate a strong irradiation environment, inducing an organic iodine conversion reaction in a simulated solution. It proposes a product extraction method and apparatus, establishes analytical methods for identifying the reaction products, and finally infers the mechanism of the organic iodine conversion reaction based on the structural characteristics of the products.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] This invention provides a method for simulating the generation of organic iodine in spent fuel reprocessing, comprising the following steps:

[0007] S1: Provide a simulated solution; the simulated solution includes an iodine-containing reagent, as well as an organic reagent and / or nitric acid; the iodine-containing reagent may be any one of ionic iodide KI, cesium triiodide, iodine molecules, iodic acid, or periodic acid;

[0008] S2: The simulated solution is placed in a quartz tube and sealed, and then irradiated by a gamma-ray source so that the simulated solution receives the corresponding irradiation dose;

[0009] S3: After irradiation, the quartz tube is opened to complete product extraction;

[0010] S4: Gas chromatography-mass spectrometry (GC-MS) was used to detect and identify the structure of the extracted product.

[0011] In this invention, in step S1, the organic reagent may be any reagent or derivative thereof involved in the spent fuel reprocessing process, including but not limited to any one of tributyl phosphate, dibutyl phosphate, monobutyl phosphate / dibutyl phosphate mixture, kerosene, n-dodecane, butyric acid, propionic acid, acetic acid, methyl acetate or methanol.

[0012] As a preferred embodiment, in some embodiments of the present invention, the simulated solution comprises an iodine-containing reagent, an organic reagent, and nitric acid; wherein the final concentration of the nitric acid is 3-6 M, such as 3 M, 3.5 M, 4 M, 4.5 M, 5 M, 5.5 M, or 6 M; the final concentration of the iodine-containing reagent is 0.4-4 mM, such as 0.4 mM, 0.5 mM, 0.8 mM, 1 mM, 1.5 mM, 2 mM, 2.5 mM, 3 mM, 3.5 mM, or 4 mM; the volume of the organic reagent is 5-20% of the total volume of the nitric acid and the iodine-containing reagent, such as 5%, 8%, 10%, 12%, 15%, 18%, or 20%, preferably 10%.

[0013] The iodine-containing reagents, organic reagents, and nitric acid mentioned above meet the above ranges in order to simulate the relevant concentrations in the field of spent fuel reprocessing. Some numerical ranges higher than the actual concentrations (such as the concentrations of iodine and organic reagents) are reasonable concentration amplifications made to explore the reaction rules.

[0014] It is important to note that when the simulated solution includes iodine-containing reagents, organic reagents, and nitric acid, it is preferable to mix the nitric acid and iodine-containing reagents first, and then add the organic reagents. This is to simulate the extraction process in spent fuel reprocessing, which involves mixing iodine-containing nitric acid solution with organic reagents.

[0015] Alternatively, in some other embodiments of the present invention, the simulated solution comprises an iodine-containing reagent and an organic reagent, but excludes nitric acid; wherein the molar ratio of the organic reagent to the iodine-containing reagent is (30~40):1, such as 30:1, 31:1, 32:1, 33:1, 34:1, 35:1, 36:1, 37:1, 38:1, 39:1 or 40:1, etc.

[0016] The molar ratio of the iodine-containing reagent and the organic reagent meets the above range in order to ensure that the organic reagent is in far excess relative to the iodine reagent, thereby providing sufficient alkyl radicals.

[0017] In some embodiments of the present invention, the quartz tube described in step S2 is subjected to impurity removal treatment before use, preferably by thoroughly cleaning it with piranha solution to eliminate interference from impurities.

[0018] According to the present invention, after obtaining the simulated solution, it is preferable to place the simulated solution in a quartz tube and seal it.

[0019] As a preferred embodiment, the simulated solution is placed in a quartz tube and then subjected to a "freezing-vacuum-melting" cycle before being sealed (also known as "low-temperature vacuum sealing technology"). The number of cycles is 2 to 6, preferably 3 to 5. The freezing in the "freezing-vacuum-melting" process is performed using an ice-water bath or liquid nitrogen, preferably liquid nitrogen.

[0020] In this invention, liquid nitrogen freezing can prevent the continuous discharge of organic reagents during the vacuum sealing process, thus avoiding the carbonization of organic reagents at the fused silica seal and their interference with the subsequent organic iodine conversion reaction, which is beneficial to gaining a clear understanding of the chemical reaction mechanism.

[0021] In this invention, the "freezing-vacuum-melting" cycle can remove some of the gas (such as air) dissolved in the simulated solution, thereby avoiding subsequent interference.

[0022] In this invention, a fused silica sealing method is used instead of the traditional reagent bottle sealed with a silicone gasket. This eliminates the possibility of the silicone gasket breaking and participating in the organic iodine conversion reaction during subsequent irradiation, as well as potential uncertainties in the subsequent reaction mechanism analysis.

[0023] As a preferred embodiment, the sealing is achieved by melting and sealing the quartz tube with an oxyhydrogen flame under vacuum freezing conditions.

[0024] According to the present invention, after sealing is completed, the quartz tube is removed and then irradiated by a gamma-ray source so that the simulated solution receives the corresponding irradiation dose.

[0025] The gamma-ray source includes, but is not limited to, Co-60. Preferably, the irradiation dose is controlled by adjusting the distance between the quartz tube and the Co-60 source and the irradiation time, with a cumulative gamma-ray irradiation dose of 50~200 kGy, such as 50 kGy, 80 kGy, 100 kGy, 120 kGy, 150 kGy, 180 kGy, or 200 kGy.

[0026] According to the present invention, after irradiation, the quartz tube is opened to complete the product extraction.

[0027] In some embodiments of the present invention, the quartz tube is subjected to a freezing treatment before being opened. The freezing treatment includes, but is not limited to, liquid nitrogen freezing, and liquid nitrogen freezing is preferred.

[0028] The product extraction described above includes liquid product extraction and / or gaseous product extraction.

[0029] As a preferred embodiment, the steps for extracting the liquid product include: immediately adding a mixing solvent after opening the quartz tube, placing the quartz tube in an ice-water bath until it melts to obtain a mixed solution, transferring the mixed solution to a separatory device, extracting the organic phase from the mixing solvent, and storing it in the dark (preferably at 4°C in a sealed container); the mixing solvent is selected from toluene and / or xylene, preferably xylene.

[0030] In this invention, the role of the mixed solvent is twofold: firstly, to stabilize the product and prevent the solution from freezing during storage and the organic iodine from volatilizing during melting; and secondly, to extract organic iodine from the aqueous solution and facilitate subsequent GC-MS analysis.

[0031] In some embodiments of the present invention, when the simulated solution contains nitric acid, the mixing solvent is added at a volume ratio of irradiated solution to mixing solvent of 3:(1~3), preferably 3:2. That is, generally 3 mL of irradiated solution is used to add 1~3 mL of mixing solvent. When the simulated solution does not contain nitric acid, the mixing solvent is added at a volume ratio of irradiated solution to mixing solvent of 1:(1~3), preferably 1:2. That is, generally 1 mL of irradiated solution is used to add 1~3 mL of mixing solvent.

[0032] The irradiated solution refers to a simulated solution that has undergone irradiation.

[0033] As a preferred embodiment, the gaseous product extraction step includes: after opening the quartz tube, connecting it to a gas collection device, applying negative pressure to transfer the volatile substances inside the quartz tube to the gas collection container of the gas collection device, and storing it in the dark. More preferably, after opening the frozen quartz tube, it is immediately connected to the gas collection device, and then a water bath is used to melt the mixture inside the quartz tube and reach a certain temperature, within the range of 25~50℃ (e.g., 25℃, 30℃, 35℃, 40℃, 45℃, or 50℃, etc.). Then, using the negative pressure of the device, the volatile substances inside the quartz tube are transferred to a gas collection bag. The gas collection bag is made of polytetrafluoroethylene (PTFE). The collected gas is stored in the dark at room temperature and under normal pressure.

[0034] In this invention, a schematic diagram of the gas collection device is shown below. Figure 4As shown, 1 is a vacuum pump; 2 is a sealed glass container with a lid; 2-1 is the main body of the glass container, and 2-2 is the lid of the glass container; 3 is the first gas passage; 4 is the second gas passage; 5 is a gas collection bag; 6 is an opened quartz tube containing irradiated liquid; and 7 is a water temperature controller. The first gas passage 3 connects the vacuum pump 1 and the sealed glass container 2; the second gas passage 4 connects the gas collection bag 5 and the opened quartz tube 6 containing irradiated liquid; and 4-1 is the switch in the second gas passage.

[0035] In some embodiments of the present invention, simply put, the gas collection device consists of a sealed glass container 2 with a lid containing two gas passages, a vacuum pump 1, and a water temperature controller 7. The outer end of the first gas passage 3 is connected to the vacuum pump 1, and the other end is placed inside the opening of the sealed glass container 2 (where 2-1 is the glass container body and 2-2 is the glass container lid). One end of the second gas passage 4 is connected to an opened quartz tube 6 containing irradiated liquid, and the other end is connected to a gas collection bag 5. The passage includes a switch 4-1. When collecting gas, first open switch 4-1 of the second gas passage 4. Heat the opened quartz tube 6 containing the irradiated solution to the set temperature using the water temperature controller 7, and wait 10-30 minutes (e.g., 10, 15, 20, 25, or 30 minutes). Then, turn on the vacuum pump 1 to create negative pressure inside the sealed glass container 2. The volatile, low-boiling-point substances in the opened quartz tube 6 containing the irradiated solution are transferred to the gas collection bag 5 through the second gas passage 4. After the gas collection bag 5 is full of gas, first close switch 4-1 of the second gas passage 4, then turn off the vacuum pump 1. After opening the sealed glass container 2, first close the valve of the gas collection bag 5 before removing the gas collection bag 5.

[0036] According to the present invention, after the product extraction is completed, the extracted product is detected and its structure is identified by gas chromatography-mass spectrometry.

[0037] In some embodiments of the present invention, the detection conditions for gas chromatography-mass spectrometry are as follows:

[0038] Column: DB-624 column;

[0039] Carrier gas: Helium, flow rate 1~3 mL / min, such as 1 mL / min, 1.5 mL / min, 2 mL / min, 2.5 mL / min or 3 mL / min, etc.;

[0040] Injection volume: 1~5 μL, such as 1 μL, 2 μL, 3 μL, 4 μL or 5 μL, etc.;

[0041] Mass spectrometry conditions: An electron bombardment ionization source is used, and the electron current is generally 60~80 eV, such as 60 eV, 65 eV, 70 eV, 75 eV or 80 eV, etc.

[0042] In some embodiments of the present invention, the extracted products are preferably detected by gas chromatography-mass spectrometry to obtain the retention time and mass spectrum of each product; the structure of the compound is identified by comparing the retention time with the standard or by comparing the mass spectrum peak characteristics with the validated mass spectrum in the spectral library.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] This invention provides a simulation method for the generation of organic iodine in spent fuel reprocessing. This method uses gamma-ray irradiation to simulate a strong irradiation environment, inducing an organic iodine conversion reaction in a simulated solution. Based on this, a product extraction method is proposed, which not only achieves qualitative and quantitative analysis of organic iodine, obtaining the organic iodine conversion capabilities of different organic reagents and different iodine compounds, but also identifies the intermediate products of the reaction. In this invention, the comprehensive acquisition of irradiation products aids in the reasoning of the organic iodine conversion mechanism, an analytical method is established to identify the reaction products, and finally, the organic iodine conversion reaction mechanism is deduced based on the structural characteristics of the products. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the simulation experiment method for the generation of organic iodine in the spent fuel reprocessing process of the present invention;

[0046] Figure 2 This is the mass spectrum of iodomethane obtained by using isotopically labeled acetic acid as an organic reagent in Example 2;

[0047] in, Figure 2 The 'a' in the text corresponds to 13 CH3COOH, Figure 2 b in the text corresponds to CD3COOD. Figure 2 The c in the formula corresponds to CH3COOH;

[0048] Figure 3 This is a comparison chart of methyl iodine production under different irradiation doses and initial iodine concentrations in Example 3;

[0049] Figure 4 This is a schematic diagram of a gas collection device;

[0050] Among them, 1 is a vacuum pump; 2 is a sealed glass container with a lid; 2-1 is the main body of the glass container; 2-2 is the lid of the glass container; 3 is the first gas passage; 4 is the second gas passage; 5 is a gas collection bag; 6 is an opened quartz tube containing irradiated liquid; 7 is a water temperature controller.

[0051] The first gas passage 3 is used to connect the vacuum pump 1 and the sealed glass container 2 with a lid; the second gas passage 4 is used to connect the gas collection bag 5 and the opened quartz tube 6 containing the irradiated liquid; 4-1 is the switch in the second gas passage.

[0052] Figure 5 The mass spectra of methanol and dimethyl ether, the key intermediates in Example 5, which were produced using CH3COOH and CD3COOD as organic sources, respectively.

[0053] in, Figure 5 In the image, a and b correspond to the mass spectra of key intermediates with CH3COOH as the organic source, where a corresponds to methanol and b corresponds to dimethyl ether.

[0054] in, Figure 5 In the mass spectra, c and d correspond to key intermediates with CD3COOD as the organic source, where c corresponds to deuterated methanol and d corresponds to deuterated dimethyl ether. Detailed Implementation

[0055] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0056] To further illustrate the present invention, the following embodiments provide a detailed description. The experimental materials used in the following embodiments of the present invention are all commercially available products.

[0057] Example 1

[0058] This embodiment provides a simulation experiment and analytical method for revealing the organic iodine generation mechanism of relevant organic reagents in spent fuel reprocessing processes. A schematic flowchart is shown below. Figure 1 As shown, the specific steps are as follows:

[0059] S1: Prepare a simulated solution containing organic reagents, an iodine-containing reagent, and nitric acid. The organic reagent should be one of the reagents and their derivatives used in spent fuel reprocessing processes, including tributyl phosphate, n-dodecane, butyric acid, propionic acid, acetic acid, methyl acetate, and methanol. The iodine-containing reagent should be KI. The preferred method is to mix the nitric acid and the iodine-containing reagent, then add the organic reagent. The final concentration of nitric acid is 4 M, the concentration of KI is 4 mM, and the volume of the organic solvent is 10% of the volume of the above solution (nitric acid + KI).

[0060] S2: The system is sealed using low-temperature vacuum encapsulation technology, including three "freezing-vacuum-melting" cycles, and the quartz tube is melt-sealed under vacuum and liquid nitrogen freezing conditions;

[0061] S3: The solution is irradiated with Co-60 to receive a dose of 200 kGy;

[0062] S4: To carry out liquid product extraction, 1) use liquid nitrogen to freeze the liquid in the quartz tube; 2) after opening the tube, immediately add the mixed solvent-xylene at a volume ratio of 3:2 for the irradiated solution to the mixed solvent; 3) place the quartz tube in an ice-water bath until the solution is completely melted; 4) transfer all the solution to a separatory funnel, extract the xylene organic phase, and store it in a reagent bottle at 4°C in the dark.

[0063] The irradiated solution refers to the simulated solution obtained after irradiation through steps S1-S3;

[0064] S5: The products were detected by GC-MS using a DB-624 column with helium as the carrier gas at a flow rate of 1.0 mL / min and an injection volume of 1 μL. The compounds were ionized by electron bombardment at 70 eV. Organic iodine was identified by comparing retention times with standards or by comparing peak characteristics with validated mass spectra in a spectral library.

[0065] Table 1 shows the organic iodine yield results (organic iodine yield results for different organic reagents, unit: mM). It is evident that small molecule acid derivatives exhibit higher organic iodine conversion yields compared to tributyl phosphate and dodecane. Furthermore, when acetic acid, propionic acid, and butyric acid are used as organic reagents, organic iodine is mainly produced in the form of iodomethane, iodoethane, and iodopropane, respectively, demonstrating a clear acid structure dependence. This leads to a mechanism for organic iodine conversion: the alkyl radicals generated from the decarboxylation of small molecule acids then participate in the formation of organic iodine.

[0066] Table 1

[0067] Tributyl phosphate n-Dodecane butyric acid propionic acid Acetic acid Methyl acetate methanol Iodomethane 0.01 0.02 0.03 0.04 3.67 2.79 0.11 Iodoethane 0.01 0.04 0.02 1.42 - - - Iodopropane 0.02 0.08 0.67 - - - -

[0068] Example 2

[0069] This embodiment provides a simulation experiment and analytical method based on isotope-labeled acetic acid to reveal the mechanism of organic iodine formation in spent fuel reprocessing. The difference from Example 1 is that in S1, three organic reagents are selected: acetic acid (CD3COOD),... 13 CH3COOH, CH3COOH, the remaining parameters and steps are consistent with those in Example 1.

[0070] The results are as follows Figure 2 Mass spectrometry analysis revealed that the methyl moiety of iodomethane inherited the isotopic labeling characteristics of the 2-C group in acetic acid, namely CD3I, CD3I, and CD3I. 13CH3I and CH3I. This example traces the origin of the methyl group in methyl iodine, demonstrating the organic iodine generation mechanism proposed in Example 1, namely, that the decarboxylation of carboxylic acids to generate alkyl radicals participates in the generation of organic iodine.

[0071] Example 3

[0072] This embodiment provides a simulation experiment and analysis method for exploring the organic iodine conversion conditions in spent fuel reprocessing. The difference from Example 1 is that in S1, the organic reagent is acetic acid CH3COOH; four concentrations of KI are used: 0.4 mM, 0.8 mM, 2 mM, and 4 mM; and four irradiation doses are used in S3: 50 kGy, 100 kGy, 150 kGy, and 200 kGy. The remaining parameters and steps are consistent with those in Example 1.

[0073] The results are as follows Figure 3 The results showed that the organic iodine conversion rate was positively correlated with the irradiation dose and the iodine source concentration.

[0074] Example 4

[0075] This embodiment provides a simulation experiment and analytical method for revealing the organic iodine formation mechanism of different iodine compounds in spent fuel reprocessing. Considering that nitric acid can induce a strong change in the chemical form of iodine, it is impossible to accurately identify the organic iodine conversion mechanism of different iodine forms. This embodiment proposes a simulation experiment method that excludes nitric acid to compare the organic iodine conversion capacity of different iodine forms.

[0076] The difference from Example 1 is that the simulated solution in S1 contains only acetic acid and an iodine-containing reagent. The iodine-containing reagent can be selected from one of the following: ionic iodide KI, cesium triiodide, iodine molecules, iodic acid, periodic acid, etc., with the molar ratio of organic reagent to iodine-containing reagent controlled at 35:1. Furthermore, the extraction of the liquid product organic iodine in S4 differs from Example 1 in that: 1) the liquid in the quartz tube is frozen using liquid nitrogen; 2) after opening the tube, xylene is added as a mixed solvent at a volume ratio of irradiated solution to mixed solvent of 1:2; 3) the quartz tube is placed in an ice-water bath until the solution is completely melted. The mixed solution is directly transferred to a reagent bottle and stored sealed at 4°C in the dark.

[0077] Table 2 shows the organic iodine yield results (organic iodine yield for different iodine-containing reagents, unit: mM). The results indicate that cesium triiodide and iodine molecules have similar organic iodine yields, which are significantly higher than those of iodide ions and higher-valence iodine compounds. Since cesium triiodide readily transforms into iodine molecules, it can be considered equivalent to the presence of iodine molecules. This demonstrates that the direct reaction between iodine molecules and alkyl groups is the most efficient organic iodine conversion pathway in this system. Among higher-valence iodine compounds, periodic acid exhibits a higher organic iodine conversion capacity compared to iodic acid.

[0078] Table 2

[0079] KI <![CDATA[CsI3]]> <![CDATA[I2]]> <![CDATA[HIO3]]> <![CDATA[H5IO6]]> Organic iodine production 19.12 119.83 118.96 10.56 50.56

[0080] Example 5

[0081] This embodiment provides a simulation experiment and analytical method for revealing the organic iodine formation mechanism of periodic acid in spent fuel reprocessing. Unlike Example 4, in S1, the simulated solution uses CD3COOD and CH3COOH for acetic acid; the iodine-containing reagent is periodic acid, and the molar ratio of acetic acid to periodic acid is controlled at 35:1. Furthermore, unlike Example 4, in S4, in addition to liquid product extraction, gaseous product extraction was also performed: the frozen quartz tube was immediately connected to a gas collection device after opening, and a water bath was used to melt the mixture inside the quartz tube and reach a certain temperature (25-50°C). Then, using the negative pressure of the device, the volatile substances inside the quartz tube were transferred to the gas collection bag. The gas collection bag is made of polytetrafluoroethylene (PTFE), and the collected gas is stored at room temperature and under normal pressure, protected from light.

[0082] Gas collection devices such as Figure 4 In this system, 1 is a vacuum pump; 2 is a sealed glass container with a lid; 2-1 is the main body of the glass container; 2-2 is the lid of the glass container; 3 is the first gas passage; 4 is the second gas passage; 5 is a gas collection bag; 6 is an opened quartz tube containing irradiated liquid; and 7 is a water temperature controller. Specifically, the first gas passage 3 connects the vacuum pump 1 and the sealed glass container 2; the second gas passage 4 connects the gas collection bag 5 and the opened quartz tube 6 containing irradiated liquid; and 4-1 is the switch in the second gas passage.

[0083] In simple terms, the gas collection device of the present invention consists of a sealed glass container 2 with a lid containing two gas passages, a vacuum pump 1, and a water temperature controller 7. In operation, the outer end of the first gas passage 3 is connected to the vacuum pump 1, and the other end is placed inside the opening of the sealed glass container 2 (where 2-1 is the main body of the glass container, and 2-2 is the lid). One end of the second gas passage 4 is connected to an opened quartz tube 6 containing irradiated liquid, and the other end is connected to a gas collection bag 5. The passage also includes a switch 4-1. When collecting gas, first open switch 4-1 of the second gas passage 4. Heat the opened quartz tube 6 containing the irradiated solution to the set temperature using the water temperature controller 7, and wait 10-30 minutes (e.g., 10, 15, 20, 25, or 30 minutes). Then, turn on the vacuum pump 1 to create negative pressure inside the sealed glass container 2. The volatile, low-boiling-point substances in the opened quartz tube 6 containing the irradiated solution are transferred to the gas collection bag 5 through the second gas passage 4. After the gas collection bag 5 is full of gas, first close switch 4-1 of the second gas passage 4, then turn off the vacuum pump 1. After opening the sealed glass container 2, first close the valve of the gas collection bag 5 before removing the gas collection bag 5.

[0084] like Figure 5 The products were identified by comparing the mass spectrometric characteristics of the products in CD3COOD and CH3COOH. Based on the product results, the organic-iodine conversion mechanism of periodic acid was deduced. The results showed that methanol and a large amount of the methanol derivative methyl acetate were detected in the liquid products. Methanol was identified as an intermediate product in the methyl radical-induced dehydroxylation reduction of periodic acid to confirm the reaction relationship. Dimethyl ether was detected in the gaseous products, confirming the occurrence of the methyl radical-induced deoxygenation reduction reaction of periodic acid. Quantitative detection of the two intermediate products and their derivatives ultimately determined the reaction mechanism.

[0085] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for simulating the generation of organic iodine in a spent fuel reprocessing process, characterized in that, Includes the following steps: S1: Provide a simulated solution; the simulated solution includes an iodine-containing reagent, as well as an organic reagent and / or nitric acid; the iodine-containing reagent is selected from any one of KI, cesium triiodide, iodine molecules, iodic acid, or periodic acid; S2: The simulated solution is placed in a quartz tube and sealed, and then irradiated by a gamma-ray source so that the simulated solution receives the corresponding irradiation dose; S3: After irradiation, the quartz tube is opened to complete product extraction; S4: Gas chromatography-mass spectrometry was used to detect and identify the structure of the extracted product.

2. The simulation experiment method according to claim 1, characterized in that, The organic reagents include, but are not limited to, any one of tributyl phosphate, dibutyl phosphate, a mixture of monobutyl phosphate and dibutyl phosphate, kerosene, n-dodecane, butyric acid, propionic acid, acetic acid, methyl acetate, or methanol.

3. The simulation experiment method according to claim 1 or 2, characterized in that, The simulated solution comprises an iodine-containing reagent, an organic reagent, and nitric acid; wherein the final concentration of the nitric acid is 3-6 M, the final concentration of the iodine-containing reagent is 0.4-4 mM, and the volume of the organic reagent is 5-20% of the total volume of the nitric acid and the iodine-containing reagent. or The simulated solution includes iodine-containing reagents and organic reagents, but excludes nitric acid; wherein the molar ratio of organic reagents to iodine-containing reagents is (30~40):

1.

4. The simulation experiment method according to claim 1, characterized in that, Before use, the quartz tube described in step S2 is subjected to impurity removal treatment; In step S2, after the simulated solution is placed in the quartz tube, it undergoes a freeze-vacuum-melt cycle before being sealed; the number of cycles is 2 to 6; the freezing in the "freeze-vacuum-melt" process is performed using an ice-water bath or liquid nitrogen. The sealing process involves sealing the quartz tube using an oxyhydrogen flame under vacuum freezing conditions.

5. The simulation experiment method according to claim 1, characterized in that, The gamma-ray source includes, but is not limited to, Co-60; The irradiation dose is 50~200 kGy.

6. The simulation experiment method according to claim 1, characterized in that, Before the quartz tube is opened, it undergoes a freezing treatment, which includes, but is not limited to, liquid nitrogen freezing.

7. The simulation experiment method according to claim 1 or 6, characterized in that, The product extraction includes liquid product extraction and / or gaseous product extraction.

8. The simulation experiment method according to claim 7, characterized in that, The steps for extracting the liquid product include: adding a mixed solvent after opening the quartz tube, placing the quartz tube in an ice-water bath until it melts to obtain a mixed solution, transferring the mixed solution to a separatory device, extracting the organic phase from the mixed solvent, and storing it in the dark; the mixed solvent is selected from toluene and / or xylene. The steps for extracting the gaseous products include: after opening the quartz tube, connecting it to the gas collection device, applying negative pressure to transfer the volatile substances in the quartz tube to the gas collection container of the gas collection device, and storing it in the dark.

9. The simulation experiment method according to claim 1, characterized in that, The detection conditions for gas chromatography-mass spectrometry are as follows: Column: DB-624 column; Carrier gas: Helium, flow rate 1~3 mL / min; Injection volume: 1~5 μL; Mass spectrometry conditions: an electron impact ionization source was used, with an electron current of 60–80 eV.

10. The simulation experiment method according to claim 1, characterized in that, In step S4, the extracted products are detected using gas chromatography-mass spectrometry to obtain the retention time and mass spectrum of each product; the structure of the compound is identified by comparing the retention time with the standard or by comparing the mass spectrum peak characteristics with the validated mass spectrum in the spectral library.

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