Method for separating Cs-137 in high-level liquid waste by multi-stage adsorption

Abstract

The application discloses a kind of methods for efficiently separating Cs-137 in high-level liquid waste by multistage adsorption, and relates to the technical field of radioactive waste disposal.The method comprises the following steps:S1, performing physicochemical property analysis on the high-level liquid waste to be treated;S2, adjusting the pH value of the high-level liquid waste to be treated according to the results of the physicochemical property analysis;S3, modifying the adsorption material to be used in the Cs-137 efficient separation device according to the proportion of different ions in the high-level liquid waste;S4, transferring the high-level liquid waste with adjusted pH value to the Cs-137 efficient separation device, and realizing efficient separation of Cs-137 by the modified adsorption material;S5, treating the separated waste liquid and the separated adsorption material respectively.The method provided by the application can quickly remove Cs-137 in the waste liquid, and the removal rate can reach more than 99%.The adsorption material used is widely available, low in price, and the finished material is non-toxic and harmless.

Description

Technical Field

[0001] This invention belongs to the field of radioactive waste disposal technology, specifically relating to a method for efficient separation of Cs-137 from high-level radioactive waste through multi-stage adsorption. Background Technology

[0002] In recent years, due to the effects of the greenhouse effect and the promotion of carbon neutrality policies, low-carbon energy has seen significant development. Nuclear energy, as a leading low-carbon energy source, has experienced rapid growth. However, commercial nuclear power plants generate large amounts of radioactive waste during operation, especially from reactor cooling systems. This waste often contains a certain amount of Cs-137, one of the main fission products of U-235 in nuclear fuel rods, characterized by its long half-life, high radiation energy, high solubility, strong migration ability, and high biotoxicity. Once released into the environment, Cs-137 from radioactive waste can cause irreparable damage to the ecological environment and human health. To address this issue, commercial nuclear power plants often use ion exchange resins to remove Cs-137 from the waste. However, this method suffers from high processing costs, resin irradiation decomposition, and secondary waste generation. Given the shortcomings of existing technologies, developing a safe, efficient, low-cost, and simple secondary waste treatment method for Cs-137 separation is imperative. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a method for efficient separation of Cs-137 from high-level radioactive waste liquid through multi-stage adsorption. This method offers a simple, safe, efficient, and low-cost process for treating secondary waste.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for efficient separation of Cs-137 from high-level radioactive waste liquid through multi-stage adsorption includes the following steps:

[0006] S1. Perform physicochemical property analysis on the high-level radioactive waste liquid to be treated;

[0007] S2. Based on the physicochemical property analysis results of the high-level radioactive waste liquid, adjust the pH value of the high-level radioactive waste liquid to be treated;

[0008] S3. Modify the adsorption material to be used in the Cs-137 high-efficiency separation device according to the proportion of different ions in the high-level radioactive waste liquid;

[0009] S4. The high-level radioactive waste liquid after pH adjustment is transferred to the Cs-137 high-efficiency separation device, and the Cs-137 is separated efficiently by the modified adsorption material.

[0010] S5. The separated waste liquid and the separated adsorption material are treated separately.

[0011] Furthermore, in the method for efficient separation of Cs-137 from high-level radioactive waste liquid via multi-stage adsorption as described above, the physicochemical property analysis items in step S1 include: analyzing the ion content in the high-level radioactive waste liquid, wherein the ions include sodium, potassium, lithium and boron, and analyzing the pH, salt content, suspended solids and nuclide content of the high-level radioactive waste liquid.

[0012] Furthermore, the method for efficient separation of Cs-137 from high-level radioactive waste liquid using multi-stage adsorption as described above employs an ICP-MS instrument to analyze the ion content in the high-level radioactive waste liquid, a rapid water content analyzer to analyze the salt content, a rapid pH analyzer to analyze the pH value, a suspended solids analyzer to analyze the suspended solids content, and a high-purity germanium gamma spectrometer to analyze the nuclide content.

[0013] Furthermore, in the method for efficient separation of Cs-137 from high-level radioactive waste liquid via multi-stage adsorption as described above, the pH value of the high-level radioactive waste liquid is adjusted to between 5 and 10 in step S2.

[0014] Furthermore, in the method for efficient separation of Cs-137 from high-level radioactive waste liquid by multi-stage adsorption as described above, the adsorption material in step S3 is one or a combination of several of the following materials: clinoptilolite, chalcogenite, Na-P1 type zeolite, type A zeolite, and type X zeolite.

[0015] Furthermore, in the method for efficient separation of Cs-137 from high-level radioactive waste liquid by multi-stage adsorption as described above, the modification of the adsorbent material in step S3 specifically involves: according to the ratio of sodium, potassium, and lithium ions determined in step S1, modifying the adsorbent material in 1-5 mol / L NaCl, KCl, or LiCl at a solid-liquid ratio of 1:1 to 1:10, and modifying it at a stirring rate of 1-100 r / min for 4-24 h at 20-25℃ to complete the modification of the adsorbent material; then installing the modified adsorbent material into the Cs-137 high-efficiency separation device.

[0016] Furthermore, in the method for efficient separation of Cs-137 from high-level radioactive waste liquid via multi-stage adsorption as described above, the Cs-137 efficient separation device in step S4 includes a liquid inlet system, a filtration system, an intelligent temperature control system, a multi-stage adsorption system, and a waste liquid temporary storage system. The liquid inlet rate of the liquid inlet system is 10-1000 L / min. The filtration system consists of a three-stage filter with pore sizes of 5 μm, 2 μm, and 0.2 μm, used to remove suspended solids from the high-level radioactive waste liquid. The intelligent temperature control system is used to control the temperature of the inlet liquid. The multi-stage adsorption system includes multi-stage zeolite adsorption filter media, each stage of which is the modified adsorption material described in step S3, used to adsorb and remove Cs-137 from the high-level radioactive waste liquid. The waste liquid temporary storage system is used to store the separated waste liquid.

[0017] Furthermore, in the method for efficient separation of Cs-137 from high-level radioactive waste liquid via multi-stage adsorption as described above, in step S4, the high-level radioactive waste liquid first enters the filtration system through the liquid inlet system to remove suspended solids; then, the temperature is controlled at around 20℃-25℃ by the intelligent temperature control system, and the waste liquid with the adjusted temperature enters the multi-stage adsorption system for efficient separation of Cs-137; after separation, the waste liquid enters the waste liquid temporary storage system.

[0018] Furthermore, in the method for efficient separation of Cs-137 from high-level radioactive waste liquid via multi-stage adsorption as described above, if the removal rate of Cs-137 from the waste liquid after one separation does not meet the requirements after radionuclide analysis in step S4, it is returned to the liquid inlet system of the Cs-137 efficient separation device, and the cycle time does not exceed 15 minutes each time.

[0019] Furthermore, in the method for efficient separation of Cs-137 from high-level radioactive waste liquid through multi-stage adsorption as described above, if the separated waste liquid in step S5 meets the emission standards for nuclear power plant effluents, it is directly discharged into the nuclear power plant waste liquid system; if it does not meet the emission standards, it is first evaporated and concentrated, and when the adsorption material in the Cs-137 efficient separation device reaches adsorption saturation, it is then subjected to cement solidification treatment together with the evaporated and concentrated waste liquid.

[0020] Compared with existing technologies, the multi-stage adsorption method for efficient separation of Cs-137 from high-level radioactive waste liquid provided by this invention has the following beneficial effects:

[0021] 1. It can quickly remove Cs-137 from waste liquid, and the treatment time for each batch of waste liquid does not exceed 15 minutes;

[0022] 2. High removal efficiency: The removal rate of Cs-137 in high-level radioactive waste liquid can reach over 99%, and after multiple cycles, almost all Cs-137 in the waste liquid can be removed.

[0023] 3. The adsorbent material used in this invention is widely available, inexpensive, and the finished product is non-toxic and harmless. Attached Figure Description

[0024] Figure 1 This is a flowchart of a method for efficient separation of Cs-137 from high-level radioactive waste liquid through multi-stage adsorption, provided in an embodiment of the present invention.

[0025] Figure 2 for Figure 1 Another flowchart of the method. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0027] Unless otherwise specified, the raw materials, reagents or devices involved in the following embodiments can be obtained from conventional commercial sources or by existing known methods.

[0028] Figure 1 and Figure 2 The following is a flowchart illustrating a method for efficient separation of Cs-137 from high-level radioactive waste liquid through multi-stage adsorption, according to an embodiment of the present invention. The method includes the following steps:

[0029] S1. Conduct physicochemical property analysis on the high-level radioactive waste liquid to be treated.

[0030] A suitable amount of high-level radioactive waste liquid was taken from the waste liquid tank of a nuclear power plant, and its sodium, potassium, lithium, and boron ion contents were analyzed. Simultaneously, its pH, salinity, suspended solids, and radionuclide content were also analyzed. Specifically, the contents of sodium, potassium, lithium, and boron were analyzed using ICP-MS; salinity was analyzed using a rapid moisture meter; pH was analyzed using a rapid pH meter; suspended solids were measured using a suspended solids analyzer; and radionuclide content was analyzed using a high-purity germanium gamma spectrometer.

[0031] S2. Adjust the pH value of the high-level radioactive waste liquid according to the physicochemical property analysis results. Specifically, adjust the pH value of the high-level radioactive waste liquid to between 5 and 10 based on the physicochemical property analysis results.

[0032] S3. Modify the adsorbent material to be used in the Cs-137 high-efficiency separation device according to the proportion of different ions in the high-level radioactive waste liquid.

[0033] The adsorbent used in the Cs-137 high-efficiency separation device is one or a combination of several of the following materials: clinoptilolite, chabazite, Na-P1 type zeolite, type A zeolite, and type X zeolite.

[0034] The specific steps for modifying the adsorbent material are as follows: Based on the ratio of sodium, potassium, and lithium ions determined in step S1, the adsorbent material is modified in 1-5 mol / L NaCl, KCl, or LiCl at a solid-liquid ratio of 1:1 to 1:10. For example, if the high-level radioactive waste liquid mainly contains sodium ions, then NaCl is used for modification.

[0035] The adsorbent material was modified at 20-25℃ with a stirring rate of 1-100 r / min for 4-24 h to complete the modification. The modified adsorbent material was then installed into a Cs-137 high-efficiency separation device.

[0036] S4. The high-level radioactive waste liquid after pH adjustment is transferred to the Cs-137 high-efficiency separation device, and the Cs-137 is separated efficiently through the modified adsorption material.

[0037] The high-efficiency Cs-137 separation device mainly includes a liquid inlet system, a filtration system, an intelligent temperature control system, a multi-stage adsorption system, and a waste liquid temporary storage system. The liquid inlet rate of the liquid inlet system is 10-1000 L / min (adjusted according to the different radionuclide concentrations in the waste liquid). The filtration system consists of three-stage filters with pore sizes of 5 μm, 2 μm, and 0.2 μm, used to remove suspended solids from high-level radioactive waste liquid. The intelligent temperature control system is used to control the liquid inlet temperature. The multi-stage adsorption system includes multi-stage zeolite adsorption filter media. The zeolite adsorption filter media used in each stage is the modified adsorption material in step S3. Each stage can remove more than 99% of Cs-137, and after multiple cycles, it can basically remove all Cs-137 from the radioactive waste liquid.

[0038] The high-level radioactive waste liquid first enters the filtration system through the inlet system to remove suspended solids. Then, the temperature is controlled at approximately 20℃-25℃ by an intelligent temperature control system. The temperature-adjusted waste liquid then enters a multi-stage adsorption system for efficient Cs-137 separation, with a residence time of approximately 2-30 minutes. After separation, the waste liquid enters a temporary waste storage system. If the Cs-137 removal rate does not meet the requirements after radionuclide analysis, it is recycled back to the high-efficiency Cs-137 separation unit, with each batch processing time not exceeding 15 minutes. If the separation requirements are met, the waste liquid is directly discharged into the nuclear power plant's waste liquid system.

[0039] S5. The separated waste liquid and the separated adsorption material are treated separately.

[0040] If the separated waste liquid meets the emission standards of nuclear power plant effluent, it can be discharged directly; if it does not meet the emission standards, it is first evaporated and concentrated. When the adsorption material in the Cs-137 high-efficiency separation device reaches adsorption saturation, it is then solidified with cement together with the evaporated and concentrated waste liquid.

[0041] Example

[0042] With 1m 3 Taking waste liquid as an example, this article details the implementation process of a highly efficient method for separating Cs-137 from radioactive waste liquid in nuclear power plants, specifically including the following steps:

[0043] 1. From 1m 3 50 ml of waste liquid was taken for physicochemical analysis to determine the content of sodium, potassium, lithium, and boron ions, as well as its pH, salt content, suspended solids, and nuclide content.

[0044] 2. Adjust the pH value of the waste liquid to between 5 and 10. Take 100g of one or more of the following materials: clinoptilolite, chabazite, Na-P1 type zeolite, type A zeolite, and type X zeolite. Based on the ratio of sodium, potassium, and lithium elements determined in step 1, modify the adsorbent material in 1-5 mol / L NaCl, KCl, and LiCl at a solid-liquid ratio of 1:1 to 1:10. After modification at 20-25℃ and a stirring rate of 1-100 r / min for 4-24 hours, the modification of the adsorbent material is completed. Then, put the modified material into a multi-stage adsorption device.

[0045] 3. Flow 1m at a rate of 10-1000 L / min 3 The waste liquid enters the filtration device to remove suspended solids. Then, the temperature is controlled at around 10℃-25℃ by an intelligent temperature control device. The waste liquid with the adjusted temperature enters the multi-stage adsorption device for efficient separation of Cs-137, with a residence time of about 2-15 minutes.

[0046] 4. If the waste liquid after adsorption meets the emission standards of nuclear power plant effluent, it can be discharged directly. If it does not meet the emission standards, it should be evaporated and concentrated first. When the adsorption material in the Cs-137 high-efficiency separation device reaches adsorption saturation, it can be solidified with cement together with the evaporated and concentrated waste liquid.

[0047] Compared with existing technologies, the multi-stage adsorption method for efficient separation of Cs-137 from high-level radioactive waste liquid provided by this invention can quickly remove Cs-137 from the waste liquid, with a processing time of no more than 15 minutes per batch; it has high removal efficiency, with a removal rate of over 99% for Cs-137 in high-level radioactive waste liquid, and can basically remove all Cs-137 from the waste liquid after multiple cycles; the adsorption materials used in this invention are widely available, inexpensive, and the finished materials are non-toxic and harmless.

[0048] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention is also intended to include these modifications and variations.

Claims

1. A method for efficient separation of Cs-137 from high-level radioactive waste liquid through multi-stage adsorption, comprising the following steps: S1. Perform physicochemical property analysis on the high-level radioactive waste liquid to be treated. The physicochemical property analysis items include: analyzing the ion content in the high-level radioactive waste liquid, wherein the ions include sodium, potassium, lithium and boron, and analyzing the pH, salt content, suspended solids and nuclide content of the high-level radioactive waste liquid. S2. Based on the physicochemical property analysis results of the high-level radioactive waste liquid, adjust the pH value of the high-level radioactive waste liquid to be treated to between 5 and 10. S3. Modify the adsorbent material to be used in the Cs-137 high-efficiency separation device according to the proportion of different ions in the high-level radioactive waste liquid; the adsorbent material is one or a combination of several of the following materials: clinoptilolite, chalcogenite, Na-P1 type zeolite, type A zeolite, and type X zeolite; the modification of the adsorbent material is specifically as follows: according to the proportion of sodium, potassium, and lithium ions determined in step S1, the adsorbent material is modified in 1-5 mol / L NaCl, KCl, or LiCl at a solid-liquid ratio of 1:1-1:10, and modified at a stirring rate of 1-100 r / min for 4-24 h at 20-25℃ to complete the modification of the adsorbent material; the modified adsorbent material is then installed in the Cs-137 high-efficiency separation device. S4. The high-level radioactive waste liquid after pH adjustment is transferred to the Cs-137 high-efficiency separation device, and Cs-137 is efficiently separated by the modified adsorption material. If the removal rate of Cs-137 in the waste liquid after one separation does not meet the requirements after radionuclide analysis, it is returned to the liquid inlet system of the Cs-137 high-efficiency separation device, and the cycle time does not exceed 15 minutes each time. S5. Treat the separated waste liquid and the separated adsorption material separately; The Cs-137 high-efficiency separation device in step S4 includes a liquid inlet system, a filtration system, an intelligent temperature control system, a multi-stage adsorption system, and a waste liquid temporary storage system. The multi-stage adsorption system includes multi-stage zeolite adsorption filter media, and each stage of zeolite adsorption filter media is the adsorption material modified in step S3, used to adsorb and remove Cs-137 from the high-level radioactive waste liquid.

2. The method for efficient separation of Cs-137 from high-level radioactive waste liquid through multi-stage adsorption according to claim 1, characterized in that, The ion content in the high-level radioactive waste liquid was analyzed using an ICP-MS instrument, the salt content was analyzed using a rapid moisture analyzer, the pH value was analyzed using a rapid pH analyzer, the suspended solids content was analyzed using a suspended solids analyzer, and the nuclide content was analyzed using a high-purity germanium gamma spectrometer.

3. The method for efficient separation of Cs-137 from high-level radioactive waste liquid through multi-stage adsorption according to claim 2, characterized in that, The liquid inlet system has an inlet rate of 10-1000 L / min; the filtration system consists of a three-stage filter with pore sizes of 5 μm, 2 μm and 0.2 μm, used to remove suspended solids from the high-level radioactive waste liquid; the intelligent temperature control system is used to control the temperature of the inlet liquid; and the waste liquid temporary storage system is used to store the separated waste liquid.

4. The method for efficient separation of Cs-137 from high-level radioactive waste liquid by multi-stage adsorption according to claim 3, characterized in that, In step S4, the high-level radioactive waste liquid first enters the filtration system through the liquid inlet system to remove suspended solids from the high-level radioactive waste liquid; then, the temperature is controlled at about 20℃-25℃ through the intelligent temperature regulation system, and the waste liquid with the adjusted temperature enters the multi-stage adsorption system for efficient separation of Cs-137; after separation, the waste liquid enters the waste liquid temporary storage system.

5. The method for efficient separation of Cs-137 from high-level radioactive waste liquid by multi-stage adsorption according to claim 4, characterized in that, If the waste liquid separated in step S5 meets the emission standards of nuclear power plant effluent, it is directly discharged into the nuclear power plant waste liquid system; if it does not meet the emission standards, it is first evaporated and concentrated, and when the adsorption material in the Cs-137 high-efficiency separation device reaches adsorption saturation, it is then treated with cement solidification together with the evaporated and concentrated waste liquid.

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