Method for chemical decontamination of a metal contaminated by radioactivity

Abstract

The application discloses a method for chemically decontaminating radioactive contaminated metal, and belongs to the technical field of metal decontamination and waste liquid zero discharge treatment. The method comprises the following steps: after cutting and decomposing the radioactive contaminated metal, the metal is placed in a chemical cleaning solution containing a chemical decontaminant for ultrasonic cleaning, placed in industrial water for static cleaning and drying treatment, and the radioactivity of the metal is detected; the collected waste liquid is treated by an adsorption leaching tower and a membrane method processor, and adjusted to neutral precipitation by adjusting the pH value. The whole decontamination process simultaneously realizes chemical decontamination of radioactive contaminated metal and recycling treatment of waste liquid, and no waste liquid is generated in the whole process. Meanwhile, the method simultaneously realizes decontamination and waste liquid treatment and recycling of artificial nuclide radioactive contaminated metal and natural nuclide radioactive contaminated metal, only a small amount of solid waste residue is generated, and radioactive waste minimization is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal decontamination and waste liquid zero discharge treatment, and particularly relates to a chemical decontamination method for radioactive contaminated metal. BACKGROUND

[0002] A certain amount of radioactive contaminated metal is generated in the process of nuclear facility operation, maintenance and decommissioning. These radioactive contaminated metals must be decontaminated whether they are directly disposed of geologically after cutting or are subjected to smelting volume reduction or reuse. The chemical decontamination method is to contact a suitable chemical reagent with the contaminated material, and finally achieve the purpose of decontamination through the dissolution of the chemical reagent to the radioactive contaminant. The chemical decontamination method can implement deep decontamination of radioactive contaminated metal, but generates a large amount of radioactive waste liquid, polluting the environment. SUMMARY

[0003] The present application aims to provide a chemical decontamination method for radioactive contaminated metal, which solves the problem of environmental pollution caused by a large amount of radioactive waste liquid generated in the current treatment of radioactive contaminated metal. The present application provides a chemical decontamination method for radioactive contaminated metal, which can not only realize decontamination treatment of radioactive metal, but also simultaneously treat the waste liquid after cleaning of artificial radionuclides and natural radionuclides, and return the qualified liquid after treatment to the chemical decontamination link for recycling.

[0004] The present application is implemented through the following technical scheme:

[0005] The present application provides a chemical decontamination method for radioactive contaminated metal, which comprises: after cutting and decomposing the radioactive contaminated metal parts, placing them in a chemical cleaning liquid containing a chemical decontaminant for ultrasonic cleaning, placing them in industrial water for static cleaning, and drying treatment, and detecting the radioactivity of the metal parts.

[0006] After the decontamination is completed, the chemical cleaning liquid in the ultrasonic cleaning and the industrial water in the static cleaning are repeatedly used until they are invalid, and then collected as waste water;

[0007] The collected waste water containing natural nuclides is pumped into an adsorption leaching tower filled with ion exchange resin for adsorption leaching, and the collected waste water containing artificial nuclides is pumped into a membrane treatment device for removal of artificial nuclides; the adsorbed radioactive waste liquid after ion exchange treatment or the filtered liquid after membrane treatment is mixed and stirred, and the mixed waste liquid is neutralized until complete precipitation, and then the filter residue is separated and discharged, and the clear liquid is separated and returned to the static cleaning.

[0008] Further, in the chemical decontamination method for radioactive contaminated metal, the chemical decontaminant is composed of water, an organic chelating agent and a surfactant, the concentration of the organic chelating agent is 0.05-3 g / L, and the concentration of the surfactant is 0.05-10 g / L.

[0009] Further, in the radioactive contaminated metal chemical decontamination method, the organic chelating agent comprises one to three of disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, iminodiacetic acid, L-(+)-tartaric acid, D-gluconic acid solution, N-hydroxyethyl ethylenediaminetriacetate, N,N-dihydroxyethylglycine, tetrasodium N,N-bis(carboxymethyl)-L-glutamate aqueous solution, 2-hydroxyphosphonoacetic acid, and thiomalic acid.

[0010] Further, in the radioactive contaminated metal chemical decontamination method, the surfactant comprises one to two of sodium dodecylbenzenesulfonate, potassium sorbate, sodium tetraborate, and triton X-100.

[0011] Further, in the radioactive contaminated metal chemical decontamination method, when the ultrasonic cleaning is performed, the ultrasonic power is 350-700w, and the ultrasonic frequency is 45-1000kHz.

[0012] Preferably, when the standing cleaning is performed, the standing cleaning time is 0.5-2h.

[0013] Further, in the radioactive contaminated metal chemical decontamination method, when the drying treatment is performed, the drying temperature is 40℃-150℃, and the drying time is 0.5-2h.

[0014] Further, in the radioactive contaminated metal chemical decontamination method, after the initial decontamination is completed, the chemical cleaning solution in the ultrasonic cleaning and the industrial water in the standing cleaning are repeatedly used for 5-20 times until the failure.

[0015] Further, in the radioactive contaminated metal chemical decontamination method, the ion exchange resin filled in the adsorption leaching tower comprises iminodiacetic acid, aminophosphonic acid, polyallylamine, cross-linked polystyrene, polyacrylonitrile, or polyacrylamide, the resin filling height is 60%-80%, and the adsorption radioactive waste liquid concentration is <1mg / L.

[0016] Further, in the radioactive contaminated metal chemical decontamination method, the membrane material used in the membrane treatment comprises microfiltration membrane, ultrafiltration membrane, or nanofiltration membrane, and the desalination rate reaches 80%-99%.

[0017] Further, in the radioactive contaminated metal chemical decontamination method, the pH value of the mixed waste liquid is 9-11, lime is used to neutralize the mixed waste liquid, 1-3g of lime powder is added per liter of the mixed waste liquid, the lime is mixed with the mixed waste liquid and stirred for 20min-50min.

[0018] Compared with the prior art, the radioactive contaminated metal chemical decontamination method has the following advantages and beneficial effects:

[0019] The chemical decontamination method for radioactive contaminated metals provided by this invention directly treats, precipitates, and separates the radioactive waste liquid generated during ultrasonic cleaning and static cleaning, then recycles it. The entire decontamination process simultaneously achieves chemical decontamination of radioactive contaminated metals and waste liquid recycling, with no waste liquid generated throughout the entire process. This decontamination method simultaneously achieves decontamination and waste liquid treatment and recycling of both artificial and natural radionuclide-contaminated metals, generating only a small amount of solid waste residue, thus minimizing radioactive waste. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0021] Figure 1 A flowchart of the chemical decontamination method for radioactive contaminated metals provided by the present invention;

[0022] Figure 2 A schematic diagram of the apparatus used in the chemical decontamination method for radioactive contaminated metals provided by the present invention.

[0023] The attached diagram shows the markings and corresponding component names:

[0024] 1-Dosing device, 2-Ultrasonic cleaning device, 3-Stationary cleaning tank, 4-Drying box, 5-Wastewater storage tank, 6-Adsorption rinsing tower, 7-Membrane treatment device, 8-Mixing tank, 9-Deep cone thickener, 10-Filtrate tank, 11-Plate and frame filter. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for explanation only and are not intended to limit the invention. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0026] The technical solution of this invention is as follows:

[0027] Please refer to Figure 1 As shown, a method for chemically decontaminating radioactive metals includes:

[0028] Step S1, after cutting and decomposing the radioactive contaminated metal parts, placing them in a chemical cleaning solution containing a chemical decontaminant for ultrasonic cleaning, placing them in industrial water for static cleaning and drying treatment, and detecting the radioactivity of the metal parts;

[0029] Step S2, after decontamination, the chemical cleaning solution in the ultrasonic cleaning and the industrial water in the static cleaning are reused until they are invalid, and then collected as waste water;

[0030] Step S3, pumping the collected waste water containing natural nuclides into an adsorption leaching tower filled with ion exchange resin for adsorption leaching, and pumping the collected waste water containing artificial nuclides into a membrane treatment device for removing artificial nuclides;

[0031] Step S4, mixing and stirring the adsorbed radioactive waste liquid after ion exchange treatment or the filtrate after membrane treatment, neutralizing the mixed waste liquid until complete precipitation, separating the filter residue and sending it out, and separating the clear liquid and returning it to the static cleaning.

[0032] The radioactive contaminated metal chemical decontamination method provided by the present application directly treats the radioactive waste liquid generated by ultrasonic cleaning and static cleaning after precipitation separation and recycling, and simultaneously realizes the chemical decontamination of radioactive contaminated metals and the recycling treatment of waste liquid in the entire decontamination process. The entire process flow does not generate waste liquid. The decontamination method of the present application simultaneously realizes the decontamination and waste liquid treatment and recycling of artificial nuclide radioactive contaminated metals and natural nuclide radioactive contaminated metals, only generates a small amount of solid waste residue, and implements radioactive waste minimization.

[0033] The decontamination object of the present application is various radioactive contaminated metal parts such as stainless steel, carbon steel and copper, and is also suitable for decontamination of radioactive surface contamination of materials such as plastic, glass or ceramic.

[0034] In step S1, the radioactive contaminated metal parts are cut and decomposed, and the radioactive metal is cut to a suitable size according to the size of the ultrasonic cleaning device and the static cleaning device and the power of the ultrasonic cleaning. A set of mechanical arm and its grabbing tool moves horizontally on the roof track under control, and performs grabbing, moving, feeding and taking operations such as cutting, ultrasonic cleaning, static cleaning, drying and detection on the radioactive contaminated waste metal.

[0035] The configuration of the chemical cleaning solution is realized by a dosing device, which includes one dosing tank and one adjustable speed stirrer. A certain amount of water and a specific radioactive chemical decontaminant are added to the dosing tank, and stirred and mixed for about 10-50 min. The water can be industrial water or qualified water after radioactive waste liquid treatment.

[0036] In step S1, the ultrasonic cleaning is carried out in an ultrasonic cleaning device, the ultrasonic cleaning device is filled with the prepared chemical cleaning solution, and the cut radioactive contaminated metal is put into the ultrasonic cleaning device by a mechanical gripper. The acoustic energy of the power ultrasonic frequency source is converted into mechanical vibration, and the ultrasonic wave is radiated to the chemical cleaning solution in the tank through the wall of the cleaning device, so that a large number of micro-bubbles are generated in the liquid in the tank and the liquid is violently turbulent, the adsorption of the dirt and the surface of the cleaned metal part is destroyed, and the effect of contact cleaning and decontamination is achieved. The ultrasonic cleaning device mainly consists of an ultrasonic cleaning tank and an ultrasonic generator. The ultrasonic cleaning tank is made of high-quality stainless steel with good strength, elasticity and corrosion resistance. The bottom is provided with an ultrasonic transducer vibrator. The ultrasonic generator generates high-frequency and high-voltage, which is transmitted to the transducer through the cable connection line. The transducer and the vibrating plate produce high-frequency resonance together, so that the solvent in the cleaning tank is cleaned by the ultrasonic wave.

[0037] In step S1, the static cleaning is carried out in a static cleaning tank. After ultrasonic cleaning, the metal part is grabbed by a mechanical gripper and put into the static cleaning tank for soaking and cleaning for 0.2-1h, and the chemical reagent on the surface of the metal part is washed away.

[0038] In step S1, the drying treatment is carried out in a hot air circulating oven. After cleaning in the water tank, the metal part is grabbed by a mechanical gripper, drained of water, and then put into a hot air circulating oven for drying. The heating temperature is 40-150℃, and the drying time is 0.5-2h. The dried metal is subjected to radioactivity detection.

[0039] In step S2, after the decontamination is completed, the chemical cleaning agent in the ultrasonic cleaning tank and the industrial water in the static cleaning tank can be reused for 5-20 times. When they are invalid, they are discharged into the flushing waste liquid storage tank and are uniformly treated after accumulating to a certain amount. Through two centrifugal pumps, the natural nuclide contamination and artificial nuclide contamination are respectively sent to the adsorption leaching tower or the membrane treatment device.

[0040] In step S3, the radioactive waste liquid containing natural nuclides is pumped into three parallel adsorption leaching towers. The adsorption leaching tower is filled with ion exchange resins such as iminodiacetic acid, amine phosphonic acid, polyallylamine, cross-linked polystyrene, polyacrylonitrile or polyacrylamide. The resin filling height is 60%-80%, and the concentration of the adsorbed radioactive waste liquid is <1mg / L.

[0041] In step S3, the radioactive waste liquid containing artificial nuclides is pumped into a membrane treatment device. The membrane materials mainly include microfiltration membrane, ultrafiltration membrane, nanofiltration membrane, etc. The membrane treatment removes artificial nuclides such as cobalt and cesium, and the desalination rate reaches 80%-99%.

[0042] In step S4, the ion exchange adsorption tail liquid or the filtration liquid of the membrane method is flowed into the 2 seat mixed stirring tank. The pH is in the range of 9-11, and the waste liquid is neutralized with lime to precipitate completely. 1-3 h of lime powder is added per liter of waste liquid, mixed with the waste liquid and stirred for about 20 min-50 min.

[0043] After stirring, the slurry is pumped into a high-efficiency deep-cone thickener by a centrifugal pump for clarification and separation, the supernatant is flowed into a filtrate tank for collection, and then pumped into a dosing tank and a static cleaning tank for recycling. The bottom radioactive waste mud is sent to a plate-and-frame filter by a centrifugal pump for filtration, the obtained filter residue is transported for disposal, and the clear liquid is returned to a clean water tank for collection.

[0044] Further, the chemical decontaminant consists of water, an organic chelating agent and a surfactant, the concentration of the organic chelating agent is 0.05-3 g / L, which can be 0.05 g / L, 0.1 g / L, 0.5 g / L, 1 g / L, 1.5 g / L, 2 g / L, 2.5 g / L, 3 g / L, etc.; the concentration of the surfactant is 0.05-10 g / L, which can be 0.05 g / L, 0.1 g / L, 0.5 g / L, 1 g / L, 1.5 g / L, 2 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L, 5 g / L, 5.5 g / L, 6 g / L, 6.5 g / L, 7 g / L, 7.5 g / L, 8 g / L, 8.5 g / L, 9 g / L, 9.5 g / L or 10 g / L, etc.

[0045] Further, the organic chelating agent includes one to three of disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, iminodiacetic acid, L-(+)-tartaric acid, D-gluconic acid solution, N-hydroxyethyl ethylenediaminetriacetate, N,N-dihydroxyethylglycine, N,N-bis(carboxymethyl)-L-glutamic acid tetrasodium solution, 2-hydroxyphosphonoacetic acid, and thiomalic acid.

[0046] Further, the surfactant includes one to two of sodium dodecylbenzenesulfonate, potassium sorbate, sodium tetraborate, and triton X-100.

[0047] Further, when ultrasonic cleaning is performed, the ultrasonic power is 350-700 w, which can be 350 w, 400 w, 450 w, 500 w, 550 w, 600 w, 650 w or 700 w, etc.; the ultrasonic frequency is 45-1000 kHz, which can be 45 kHz, 100 kHz, 200 kHz, 300 kHz, 400 kHz, 500 kHz, 600 kHz, 700 kHz, 800 kHz, 900 kHz or 1000 kHz, etc.; preferably, when static cleaning is performed, the static cleaning time is 0.5-2 h, which can be 0.5 h, 1 h, 1.5 h, 2 h, etc.

[0048] Further, when the drying treatment is performed, the drying temperature is 40-150°C, which can be 40°C, 60°C, 75°C, 80°C, 100°C, 120°C, 140°C, or 150°C; and the drying time is 0.5-2h, which can be 0.5h, 1h, 1.5h, or 2h.

[0049] Further, after the initial decontamination is completed, the chemical cleaning solution in the ultrasonic cleaning and the industrial water in the standing cleaning are repeatedly used 5-20 times until they are disabled.

[0050] Further, the ion exchange resin filled in the adsorption and leaching tower includes iminodiacetic acid, amine phosphonic acid, polyallylamine, cross-linked polystyrene, polyacrylonitrile, or polyacrylamide, the resin filling height is 60%-80%, and the adsorption concentration of the radioactive waste liquid is less than 1mg / L.

[0051] Further, the membrane material used in the membrane treatment includes microfiltration membrane, ultrafiltration membrane, or nanofiltration membrane, and the desalination rate reaches 80%-99%.

[0052] Further, the pH value of the mixed waste liquid is 9-11, and the mixed waste liquid is neutralized by lime, 1-3g of lime powder is added per liter of the mixed waste liquid, and the mixed waste liquid is mixed and stirred for 20-50min.

[0053] Please refer to Figure 2 The device used in the radioactive contaminated metal chemical decontamination method includes a decontamination device and a waste liquid recycling treatment device.

[0054] The decontamination device includes a dosing device 1 for configuring a chemical cleaning solution; the dosing device includes a dosing tank and a speed-adjustable stirrer, and a certain amount of industrial water and a specific radioactive chemical decontaminant are added to the dosing tank.

[0055] An ultrasonic cleaning device 2 is connected with the dosing device 1, and the chemical cleaning solution in the dosing device 1 is pumped into the ultrasonic cleaning device to perform ultrasonic cleaning on the radioactive contaminated metal parts after cutting and decomposition.

[0056] A standing cleaning tank 3 is connected with the ultrasonic cleaning device 2, and is used for standing cleaning of the metal parts after the ultrasonic cleaning.

[0057] A drying box 4 is connected with the standing cleaning tank 3, and is used for drying treatment of the metal parts after the standing cleaning; the drying box can be a hot air circulation oven, and after cleaning in the water tank, the metal parts are grabbed by a mechanical gripper, drained, and then placed in the hot air circulation oven for drying; and the dried metal parts are subjected to radioactive detection.

[0058] The waste liquid recycling treatment device includes:

[0059] Waste water storage tank 5, the chemical cleaning agent in the ultrasonic cleaning tank and the industrial water in the standing cleaning tank can be reused 5-20 times, and after failure, they are discharged into the flushing waste liquid storage tank;

[0060] Adsorption leaching tower 6, the radioactive waste liquid containing natural nuclides is pumped into 3 parallel adsorption leaching towers.

[0061] Membrane treatment device 7, the radioactive waste liquid containing artificial nuclides is pumped into the membrane treatment device, and the membrane treatment filtration removes cobalt, cesium and other artificial nuclides.

[0062] Mixing tank 8, the ion exchange adsorption tail liquid or the membrane treatment filtration liquid flows into 2 mixing tanks. The pH is in the range of 9-11, and the waste liquid is completely precipitated by neutralization with lime.

[0063] Precipitation separation device, after stirring, the slurry is pumped into the high-efficiency deep-cone thickener 9 for clarification and separation, the supernatant flows into the filtrate tank 10 for collection, and then is pumped into the dosing tank and the standing cleaning tank for recycling. The bottom radioactive waste mud is sent to the plate-and-frame filter 11 for filtration, the obtained filter residue is shipped for disposal, and the clear liquid is returned to the clean water tank for collection.

[0064] In order to further illustrate the present application, the following embodiments are used to describe the radioactive contaminated metal chemical decontamination method provided by the present application, but it should be understood that these embodiments are implemented on the basis of the technical scheme of the present application, and detailed implementation modes and specific operation processes are given, which are only for further illustrating the features and advantages of the present application, and are not a limitation on the claims of the present application, and the protection scope of the present application is not limited to the following embodiments.

[0065] Example 1

[0066] The radioactive contaminated metal chemical decontamination method of the present embodiment comprises the following steps:

[0067] 1. Radioactive metal cutting and decomposition

[0068] Long pipes are cut to less than 1000 mm, and plates are cut to less than 1000 mm*1000 mm, and a single mechanical arm with a maximum clamping capacity of 80 kg and its grabbing tool are used to transport the cut and sorted metal contaminated parts to the chemical decontamination device site.

[0069] 2. Preparation of chemical cleaning solution

[0070] The dosing device includes one dosing tank MC-200L, φ580*930, one agitator, and a motor 0.55 kw; and one frequency converter is used to adjust the rotation speed of the agitator. A certain amount of water and specific radioactive chemical decontaminant are added to the dosing tank, and stirring and mixing are performed for about 30 min.

[0071] 3. Ultrasonic cleaning

[0072] Ultrasonic cleaning device, shape 1.8 m x 0.8 m x 0.7 m, inner tank 1.6 m x 0.6 m x 0.5 m (L x W x H), 480 L, ultrasonic power 7.68 KW, heating power 5 KW, power supply 380 V, with a basket, can be lifted 1.5 t. The first batch can handle about 1.5 t.

[0073] 4. Static cleaning

[0074] After ultrasonic cleaning, the metal parts are grabbed by mechanical grippers and placed in the static cleaning tank for a period of time to soak and clean the surface of the metal parts.

[0075] 5. Drying and radioactivity detection

[0076] Hot air circulating oven, shape 4.6 m x 2.2 m x 2.3 m (L x W x H), drying capacity 400-1000 kg each time, circulating fan 1.8 kw, exhaust fan 1.1 kw, electric heating 48 kw, heating temperature 50-130℃, circulating air volume 13500 m3 / h. Heating temperature 80℃.

[0077] 6. After the decontamination is completed, the chemical cleaning agent in the ultrasonic cleaning tank and the industrial water in the static cleaning tank can be reused for 10 times, and after failure, they are discharged into the flushing waste liquid storage tank. The flushing waste liquid storage tank has a volume of 4 m x 2 m x 2 m (L x W x H) and a volume of 16 m3. Through two centrifugal pumps, it is sent to the adsorption leaching tower or membrane treatment device according to natural nuclide pollution and artificial nuclide pollution. Horizontal centrifugal pump Q = 0.5 m3 / h, H = 30 m, P = 1.1 kW

[0078] 7. Adsorption leaching

[0079] The radioactive waste liquid containing natural nuclides is pumped into the adsorption leaching tower, and the uranium and resin in the adsorption leaching tower are ion exchanged. The adsorption leaching tower has 3 parallel connections, the ion exchange equipment material is white transparent column, the outer size is DN200*2000, the empty tower flow rate is 20 m / h, the resin filling height is 1.5 m, the resin saturation capacity is 6.5 mg / mLR, the treatment capacity is 800 L / h, and the adsorption tail liquid uranium concentration is 0.5 mg / L.

[0080] 8. Membrane treatment

[0081] The radioactive waste liquid containing artificial nuclides is pumped into the membrane treatment device, and the membrane treatment removes artificial nuclides such as cobalt and cesium through filtration, with a treatment capacity of 1 t / h, a desalination rate of 99%, and an outlet water conductivity of ~ 10 μm / cm.

[0082] 9. Lime neutralization

[0083] The ion exchange adsorption tail liquid or the filtrate treated by membrane method flows into the mixing and stirring tank. Lime powder is added into the waste liquid and stirred for reaction for about 30 min.

[0084] 10. Precipitation separation

[0085] After stirring, the slurry is pumped into a high-efficiency deep-cone thickener by two centrifugal pumps for clarification and separation. The high-efficiency deep-cone thickener has a diameter of 2000 mm and a length of 3000 mm, a volume of 6.28 m3, and a stirring power of 1.5 kW. The supernatant flows into a filtrate tank for collection, and then is pumped into a dosing tank and a static cleaning tank for recycling. The filtrate tank has a diameter of 2000 mm and a length of 2000 mm, and a volume of 6.28 m3. The bottom slurry is pumped to a plate-and-frame filter by a centrifugal pump for filtration, and the obtained filter residue is transported for disposal, and the clear liquid is returned to a clean water tank for collection. The horizontal centrifugal pump has a flow rate of 5 m3 / h, a head of 60 m, and a power of 4 kW.

[0086] The above detailed description further explains the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for chemically decontaminating radioactive metals, characterized in that, include: After cutting and disassembling radioactive contaminated metal parts, they are placed in a chemical cleaning solution containing chemical detergent for ultrasonic cleaning, placed in industrial water for static cleaning, and dried. The radioactivity of the metal parts is then tested. After the cleaning process is completed, the chemical cleaning solution used in the ultrasonic cleaning and the industrial water used in the static cleaning are reused until they become ineffective and are then collected as wastewater. The collected wastewater containing natural radionuclides is pumped to an adsorption and rinsing tower filled with ion exchange resin for adsorption and rinsing. The collected wastewater containing artificial radionuclides is pumped to a membrane processor for removal of artificial radionuclides. The radioactive waste liquid after ion exchange treatment or the filtrate after membrane treatment is mixed and stirred. The mixed waste liquid is neutralized until precipitation is complete. The filter residue is separated by precipitation and sent out. The clear liquid is returned to the settling and cleaning process. The chemical detergent is composed of water, an organic chelating agent, and a surfactant. The concentration of the organic chelating agent is 0.05–3 g / L, and the concentration of the surfactant is 0.05–10 g / L. The pH value of the mixed waste liquid is 9-11. The mixed waste liquid is neutralized with lime. 1-3g of lime powder is added per liter of mixed waste liquid, and the mixture is stirred and reacted for 20-50 minutes. The organic chelating agent comprises one to three of the following: disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, tetrasodium iminodisuccinate, L-(+)-tartaric acid, D-gluconic acid solution, N-hydroxyethylethylenediaminetriacetic acid, N,N-dihydroxyethylglycine, aqueous solution of tetrasodium N,N-bis(carboxymethyl)-L-glutamate, 2-hydroxyphosphonoacetic acid, and thiomalic acid. The surfactants include one or two of the following: sodium dodecylbenzenesulfonate, potassium sorbate, sodium stearate, and dishwashing liquid.

2. The method for chemical decontamination of radioactive contaminated metals according to claim 1, characterized in that, When performing ultrasonic cleaning, the ultrasonic power is 350-700W and the ultrasonic frequency is 45-1000kHz; preferably, when performing static cleaning, the static cleaning time is 0.5-2h.

3. The method for chemical decontamination of radioactive contaminated metals according to claim 1, characterized in that, When drying, the drying temperature is 40℃~150℃ and the drying time is 0.5~2h.

4. The method for chemical decontamination of radioactive contaminated metals according to claim 1, characterized in that, After the initial cleaning, the chemical cleaning solution used in the ultrasonic cleaning and the industrial water used in the static cleaning are reused 5 to 20 times until they become ineffective.

5. The method for chemical decontamination of radioactive contaminated metals according to claim 1, characterized in that, The ion exchange resins filled in the adsorption scrubbing tower include: iminodiacetic acid, aminophosphonic acid, polyallylamine, cross-linked polystyrene, polyacrylonitrile, or polyacrylamide. The resin filling height is 60% to 80%, and the concentration of radioactive waste liquid adsorbed is <1 mg / L.

6. The method for chemical decontamination of radioactive contaminated metals according to claim 1, characterized in that, The membrane materials used in membrane treatment include microfiltration membranes, ultrafiltration membranes, or nanofiltration membranes, with desalination rates reaching 80% to 99%.

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