Detergent for removing typical pollution nuclides in nuclear power plant and preparation method

Abstract

The invention relates to a detergent for removing typical pollution nuclides in a nuclear power plant and a preparation method of the detergent. The detergent comprises the following raw materials in percentage by weight: 3-9% of a surfactant, 1-5% of a chelating agent, 0.05-1% of a viscosity modifier and 85-96% of water. The detergent for removing typical pollution nuclides in the nuclear power plant can efficiently remove nuclides and has no corrosion risk to nuclear power plant equipment.

Description

Technical Field

[0001] This invention relates to the field of radioactive contaminant removal technology in the nuclear industry, and in particular to a decontaminant and its preparation method for removing typical contaminating nuclides in nuclear power plants. Background Technology

[0002] In recent years, my country's nuclear power industry has flourished, with nuclear power plant construction booming and providing enormous energy resources for humanity. One of the main challenges in the operation and maintenance of nuclear power plants is the radiation and environmental risks posed by radioactive contamination. During operation, nuclear power plants generate radioactive contamination through neutron activation. 59 Fe、 60 Co、 110m Ag and other activated corrosion products. These metallic nuclides are the main source of radioactive contamination in nuclear power plants. They are widely present in reactor fuel assemblies and internal components, and are also distributed throughout the plant via piping systems, depositing on the surfaces of valves, instruments, and bends in the main circuit, chemical and fluid dynamics systems, etc., causing radiation exposure to workers during operation and maintenance. Especially during major overhauls, they become the primary contributor to the radiation exposure of equipment maintenance personnel. Therefore, the removal of these contaminating nuclides during the operation and maintenance of nuclear facilities is essential.

[0003] Chemical decontamination agents are the most common method for removing radioactive contaminants from the surface of objects to be decontaminated. Chemical decontamination agent formulations contain various components, such as surfactants, active decontaminants, stabilizers, and auxiliaries. Currently, domestically developed chemical decontamination agent formulations typically use highly corrosive chemicals such as strong acids (e.g., nitric acid), strong bases (e.g., sodium hydroxide), and strong oxidants (e.g., cerium ammonium nitrate) as active decontaminants. Clearly, while these active decontaminants remove radionuclides, they can also corrode the substrate of nuclear power plant facilities, potentially causing the facilities to lose their structural and functional integrity, making them unsuitable for nuclear power plant decontamination. Therefore, using safe and highly effective decontaminants is crucial for developing decontamination agents for nuclear power plants. These issues urgently need to be addressed. Summary of the Invention

[0004] This invention discloses a decontaminant and its preparation method for removing typical polluting nuclides in nuclear power plants, aiming to solve the technical problems existing in the prior art.

[0005] The present invention adopts the following technical solution: In a first aspect, the present invention provides a decontaminant for removing typical contaminating nuclides in nuclear power plants, the decontaminant comprising the following raw material composition and the weight percentage of each component as follows: 3-9% surfactant, 1-5% chelating agent, 0.05-1% viscosity modifier and 85-96% water.

[0006] In a decontaminant for removing typical contaminating radionuclides in nuclear power plants according to the present invention, the surfactant is one or more of sodium stearate, nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, dodecyl dimethylamine oxide, and tetradecyl dimethylamine oxide.

[0007] In a decontaminant for removing typical polluting nuclides in nuclear power plants according to the present invention, the chelating agent is one or more of 1-aza-18-crown-6, 1,4,7,10-tetrathia-13-azacyclopentadecane, and calix[4] aromatics.

[0008] In a decontaminant for removing typical contaminating nuclides in nuclear power plants according to the present invention, the chelating agent is 1-aza-18-crown-6; this chelating agent results in the highest decontamination rate for contaminated samples, while exhibiting the least corrosiveness to stainless steel samples.

[0009] In a decontaminant for removing typical contaminating radionuclides in nuclear power plants according to the present invention, the viscosity modifier is one or more of polyacrylic acid, polyacrylamide, polyethylene glycol, and polyvinylpyrrolidone.

[0010] In a decontaminant for removing typical contaminating nuclides in nuclear power plants according to the present invention, the surfactant has a weight percentage of 3%, the chelating agent has a weight percentage of 3%, the viscosity modifier has a weight percentage of 0.05%, and the water has a weight percentage of 93.95%.

[0011] In a second aspect, the present invention also provides a method for preparing any of the detergents described above, comprising the following steps: Prepare the raw materials and divide the raw material water into two parts; add viscosity regulator to one part of the water while stirring until it is mixed evenly to obtain a viscosity regulator solution; Add the surfactant and chelating agent to another water and stir until dissolved to obtain a mixed solution; Add the mixed solution to the obtained viscosity modifier solution and stir until homogeneous to obtain a detergent.

[0012] The technical solution adopted in this invention can achieve the following beneficial effects: This invention provides a decontaminant for removing typical polluting nuclides in nuclear power plants, which can efficiently remove nuclides without posing a risk of corrosion to nuclear power plant equipment. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. In the description of this invention, it should be noted that the term "or" is generally used to include the meaning of "and / or," unless otherwise expressly indicated.

[0014] Unless explicitly stated otherwise, the numerical parameters in this specification and the appended claims may be approximate values ​​and can be varied according to the desired characteristics obtained from the content of this invention. Specifically, all figures used in the specification and claims to indicate the content of composition, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. Generally, this means that there may be variations of ±10% in some embodiments, ±5% in some embodiments, ±1% in some embodiments, and ±0.5% in some embodiments.

[0015] Furthermore, the word "comprising" does not exclude the presence of materials or steps not listed in the claims. The ordinal numbers used in the specification and claims, such as "first," "second," "third," and Arabic numerals and letters, to modify corresponding elements or steps, do not in themselves imply an order of manufacturing process; their use is solely to ensure clear distinction between steps.

[0016] Furthermore, unless specifically described or required to occur in a specific order, the order of the above steps is not limited to those listed above and can be varied or rearranged according to the desired design. Moreover, the above embodiments can be used in combination with each other or with other embodiments based on design and reliability considerations; that is, technical features from different embodiments can be freely combined to form more embodiments.

[0017] Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0018] To address the problems existing in the prior art, this application provides a decontaminant and its preparation method for removing typical polluting nuclides in nuclear power plants.

[0019] Example 1 In this embodiment, the radioactive detergent has the following composition by weight percentage: 3% nonylphenol polyoxyethylene ether, 3% 1-aza-18-crown-6, 0.05% polyethylene glycol, and the balance being water.

[0020] The preparation method of the above-mentioned radioactive detergent is as follows: ① Add polyethylene glycol to one part of the water while stirring until it is mixed evenly to obtain a viscosity modifier solution; ② Add fatty alcohol polyoxyethylene ether and 1-aza-18-crown-6 to another water, stir until dissolved, and obtain a mixed solution; ③ Add the mixed solution obtained in step ② to the viscosity regulator solution obtained in step ①, stir and mix evenly to obtain the detergent.

[0021] Example 2 The detergent prepared in Example 1 was subjected to a stability test. The experimental procedure was as follows: Two portions of detergent, each no less than 100 mL, were placed in 250 mL colorless, stoppered, wide-mouthed glass bottles. One portion was placed in a refrigerator at -5℃±2℃ for 24 hours. After being removed and allowed to return to room temperature, the presence of any precipitation or discoloration was observed, and the product was checked for transparency and turbidity. The other portion was placed in an insulated box at 40℃±2℃ for 24 hours. After being removed and allowed to return to room temperature, the presence of any odor, layering, or discoloration was observed, and the product was checked for transparency and turbidity.

[0022] After the test, the two detergent samples were compared with the original sample, and no significant difference was observed, indicating that the detergent of the present invention has good stability.

[0023] Example 3 The detergent prepared in Example 1 was subjected to a detergent removal experiment. The detergent removal process is as follows: ① Preparation of simulated stainless steel samples with fixed contamination from multiple nuclides 59Fe, 60Co, and 110mAg (Methods: RLDemmer. Development of Simulated Contamination (SIMCON) and Miscellaneous Decontamination Scoping Tests, Westinghouse Idaho Nuclear Company, Inc., 1994.) ② A simulated stainless steel sample with fixed contamination from multiple nuclides 59Fe, 60Co, and 110mAg was suspended in the center of the detergent solution prepared in Example 1; ③ Place the container holding the detergent solution in an ultrasonic cleaner and ultrasonically clean it. The specific ultrasonic cleaning conditions are: ultrasonic power density 30W / cm², ultrasonic frequency 30KHz, and time 10min. ④ After the decontamination is completed, remove the contaminated sample, let it air dry naturally, and use a surface contamination meter to measure the radioactivity on the surface of the contaminated sample.

[0024] The results showed that the contamination level on the surface of the stainless steel sample decreased from 643.04 cps to 63.91 cps after decontamination, and the removal rate of fixed contaminants on the surface reached 90.06%. This indicates that the ultrasonic decontaminant of the present invention has a significant removal effect on typical multi-element nuclides 59Fe, 60Co, and 110mAg on the stainless steel surface of nuclear facilities.

[0025] Example 4 The corrosive effect of the detergent on stainless steel samples was evaluated by testing the change in corrosion rate of stainless steel samples before and after cleaning in AP1000 pipeline simulated solution. The experimental procedure is as follows: ① Configure AP1000 pipeline simulation fluid; ② Set the reference electrode to a saturated calomel electrode, the auxiliary electrode to a platinum electrode, and the working electrode to a stainless steel sample. Test the polarization curve of the stainless steel sample before decontamination in the AP1000 pipeline simulation solution using an electrochemical workstation, and analyze the measured polarization curves to obtain the corrosion rate. ③ The stainless steel sample was decontaminated using the detergent prepared in Example 1. Specifically, the stainless steel sample was suspended in the detergent solution for one hour, then taken out, washed with water and dried. ④ Refer to step ② to determine the polarization curve of the decontaminated stainless steel sample in the AP1000 pipeline simulation solution, and calculate the corrosion rate.

[0026] The results showed that the corrosion rates of the stainless steel samples before and after decontamination in the AP1000 pipeline simulation solution were 0.00734 and 0.00796, respectively, with very little difference between them. This indicates that the radioactive decontaminant of the present invention is a safe decontaminant and will not cause electrochemical corrosion to the stainless steel substrate of nuclear facilities.

[0027] The embodiments of the present invention have been described above. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A decontaminant for removing typical contaminating nuclides in a nuclear power plant, characterized by, The raw material composition of the decontaminant comprises and the weight percentage of each component is as follows: 3-9% of surfactant, 1-5% of chelating agent, 0.05-1% of viscosity modifier and 85-96% of water.

2. A decontaminant for removing typical contaminant nuclides in a nuclear power plant according to claim 1, characterized in that, The surfactant is one or several of sodium stearate, nonylphenol polyoxyethylene ether, octylphenol polyoxyethylene ether, dodecyl dimethyl amine oxide and tetradecyl dimethyl amine oxide.

3. A decontaminant for removing typical contaminant nuclides in a nuclear power plant according to claim 1, characterized in that, The chelating agent is one or several of 1-aza-18-crown-6, 1,4,7,10-tetrathia-13-azacyclopentadecane and calix[4]arene.

4. A decontaminant for removing typical contaminant nuclides in a nuclear power plant according to claim 3, characterized in that, The chelating agent is 1-aza-18-crown-6.

5. The decontaminant for removing typical contaminant nuclides in a nuclear power plant according to claim 1, characterized in that, The viscosity modifier is one or several of polyacrylic acid, polyacrylamide, polyethylene glycol and polyvinylpyrrolidone.

6. A decontaminant for removing typical contaminant nuclides in nuclear power plants according to claim 1, characterized in that, The weight percentage of the surfactant is 3%, the weight percentage of the chelating agent is 3%, the weight percentage of the viscosity modifier is 0.05%, and the weight percentage of the water is 93.95%.

7. A process for the preparation of a detergent as claimed in any one of the preceding claims 1 to 6, characterised in that, The method comprises the following steps: Prepare raw materials and divide the water into two parts; add the viscosity modifier to one part of the water while stirring until the mixture is uniform to obtain a viscosity modifier solution; Add the surfactant and the chelating agent to the other part of the water and stir until dissolved to obtain a mixed solution; Add the mixed solution to the viscosity modifier solution and stir until uniform to obtain the decontaminant.