Decommissioning detergent for radioactive waste liquid evaporator, preparation method and use method of decommissioning detergent

Abstract

The invention provides a decommissioning detergent for a radioactive waste liquid evaporator, which is prepared from the following components in parts by mass: 4 to 10 parts of organic acid, 12 to 28 parts of inorganic acid, 1 to 3 parts of complexing agent, 3 to 6 parts of slow release agent, 0.1 to 1.0 part of surfactant and 50 to 85 parts of deionized water. The invention further provides a preparation method and a use method of the decommissioning detergent for the radioactive waste liquid evaporator. According to the decommissioning detergent for the radioactive waste liquid evaporator as well as the preparation method and the use method of the decommissioning detergent, the decommissioning detergent is good in decontamination effect, low in corrosivity, easy to treat, safe and environmentally friendly.

Description

Technical Field

[0001] The invention relates to the technical field of radioactive element processing, and in particular to a decommissioning decontaminant for a radioactive waste liquid evaporator, a preparation method and a use method thereof. Background Art

[0002] After years of operation, the inner wall and corresponding components of the radioactive waste liquid evaporator will be contaminated by radioactivity. Once the radioactive waste liquid evaporator enters the decommissioning stage, it needs to be effectively disposed of.

[0003] In foreign countries, the treatment of radioactive waste liquid evaporators in the decommissioning stage is often carried out by delaying decommissioning or isolating decommissioning, and it is rarely treated by decontamination or dismantling.

[0004] According to the regulations and systems for decommissioning of nuclear facilities in my country, nuclear facilities need to undergo certain decontamination before dismantling to reduce the level of radioactivity and the exposure dose to workers during the dismantling process, in order to achieve the purpose of decontamination and degradation, meet the requirements for dismantling and disintegration of subsequent equipment, reduce the protection requirements at the work site and the generation of high-level aerosols during the operation.

[0005] For the decommissioning and decontamination of radioactive waste liquid evaporators, reducing potential nuclear safety risks, selecting what decontamination technology and what decontamination plan to adopt to achieve the decommissioning and decontamination of radioactive waste liquid evaporators are issues we must face.

[0006] At present, there are many methods used for decontamination of nuclear facilities at home and abroad, mainly including wiping decontamination, vacuum decontamination, spray decontamination, high-pressure water jet decontamination, abrasive jet decontamination, dry ice decontamination, ultrasonic decontamination, immersion decontamination, acid-base alternation decontamination, atomization decontamination, foam decontamination, gel decontamination, complexation decontamination, chemical decontamination, etc. In addition, new technologies such as microwave decontamination, laser decontamination, plasma decontamination, supercritical decontamination, and biological decontamination have also been widely used in decontamination of nuclear facilities.

[0007] Among them, chemical decontamination methods have attracted attention due to their good compatibility with the decontamination object, low cost, simple operation and high efficiency. However, chemical decontamination agents still have the disadvantage of poor decontamination effect and are prone to cause excessive corrosion to nuclear facility components. After chemical decontamination of nuclear facility components, it is difficult for the wastewater treatment system to process them, which is likely to cause a significant impact on the environment.

[0008] Therefore, there is an urgent need for a decommissioning decontaminant for radioactive waste liquid evaporators that has good decontamination effect, is less corrosive to nuclear facility components, is easily treated by a wastewater treatment system, and is safe and environmentally friendly. Summary of the invention

[0009] The technical problem to be solved by the present invention is to provide a decommissioning decontaminant for a radioactive waste liquid evaporator which has good decontamination effect, low corrosivity, is easy to handle, safe and environmentally friendly, and a preparation method and a use method thereof.

[0010] In order to solve the above technical problems, the present invention provides a decommissioning decontaminant for a radioactive waste liquid evaporator, which comprises, by weight, 4-10 parts of an organic acid, 12-28 parts of an inorganic acid, 1-3 parts of a complexing agent, 3-6 parts of a sustained-release agent, 0.1-1.0 parts of a surfactant, and 50-85 parts of deionized water.

[0011] Furthermore, the organic acid is one or more of ascorbic acid, oxalic acid, acetic acid, and succinic acid.

[0012] Furthermore, the inorganic acid is one or more of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid.

[0013] Furthermore, the complexing agent is one or more of ethylenediaminetetramethylene phosphate sodium, diethylenetriaminepenta(methylene phosphonate) and ethylenediaminetetraacetic acid disodium.

[0014] Furthermore, the sustained-release agent is one or more of polyaspartic acid, triethanolamine, sodium thioacetate and ammonium thioacetate.

[0015] Furthermore, the surfactant is one or more of polyacrylamide, stearic acid, and sodium dodecylbenzene sulfonate.

[0016] The invention provides a method for preparing a decommissioning decontaminant for a radioactive waste liquid evaporator, comprising: adding the organic acid into deionized water, stirring for 5 to 15 minutes, and then sequentially adding the inorganic acid, a complexing agent, a sustained-release agent, and a surfactant, stirring for 5 to 15 minutes each time a reagent is added.

[0017] The present invention also provides a method for using a decontaminant for a radioactive waste liquid evaporator, comprising the following steps:

[0018] injecting a decontaminant into a radioactive waste liquid evaporator, heating the decontaminant, and using a centrifugal pump to circulate the decontaminant in the radioactive waste liquid evaporator for cleaning and decontamination;

[0019] After cleaning with the detergent, the detergent in the radioactive waste liquid evaporator is emptied, and then the radioactive waste liquid evaporator is circulated and flushed with deionized water.

[0020] Furthermore, the temperature of the decontaminant after being heated in the radioactive waste liquid evaporator is 30-45° C., and the flow rate of the decontaminant circulating in the radioactive waste liquid evaporator is 1-3 m / s.

[0021] Furthermore, the cleaning and decontamination time of the decontaminant in the radioactive waste liquid evaporator is 20 to 60 minutes.

[0022] The present invention provides a decommissioning decontaminant for a radioactive waste liquid evaporator, which adopts a formula combining an organic acid and an inorganic acid. Compared with an organic acid, an inorganic acid can directly release hydrogen ions to react chemically with the oxide layer on the surface of the radioactive waste liquid evaporator, thereby dissolving the oxide layer on the surface of the radioactive waste liquid evaporator, releasing the radioactive nuclides in the oxide layer, and strengthening the decontamination process. Moreover, since the decontaminant of the present application uses strong inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, in order to avoid excessive corrosion, the present application adds an appropriate amount of organic acid and corrosion inhibitor to the formula, so as to alleviate or control the corrosion rate to a certain extent, and avoid further corrosion of the radioactive waste liquid evaporator body. Adding a small amount of surfactant to the formula helps to reduce the surface tension of the decontaminant, ensuring that the decontaminant can better contact the oxide layer on the surface of the radioactive waste liquid evaporator to promote the reaction between the oxide layer and the acid. Therefore, the decontamination agent for decommissioning a radioactive waste liquid evaporator provided by the present invention can fully react chemically with the oxide layer on the surface of the radioactive waste liquid evaporator, remove the oxide layer on the surface of the radioactive waste liquid evaporator, achieve the purpose of chemical decontamination, and has good decontamination performance, with a decontamination factor of more than 100. At the same time, it is not easy to react with the body of the radioactive waste liquid evaporator, has less corrosiveness to the radioactive waste liquid evaporator, and the average corrosion depth of the radioactive waste liquid evaporator is less than 0.1um.

[0023] Furthermore, the present invention provides a decontamination agent for decommissioning a radioactive waste liquid evaporator, and its component reagents are common industrial products, which are easy to purchase, cheap, and have a low comprehensive decontamination cost. Furthermore, the present invention adds a small amount of complexing agent to the detergent formula, and the complexing agent can be used to complex the radioactive nuclides released by the reaction to avoid their impact on the environment. Therefore, after the decontamination agent provided by the present invention decontaminates the radioactive waste liquid evaporator reaction, the amount of waste generated is small, and no toxic substances are generated. At the same time, the decontamination agent components provided by the present invention and the waste generated after decontamination do not contain harmful ions that affect the wastewater treatment system, and have good compatibility with the wastewater evaporation treatment system, so that the impact on the environment is small, safe, non-toxic, and green and environmentally friendly.

[0024] At the same time, the decontamination agent for decommissioning a radioactive waste liquid evaporator provided by the present invention is simple and quick in preparation and use, and the preparation of the decontamination agent can be completed in one hour with deionized water at room temperature. The radioactive waste liquid evaporator in the decommissioning stage can be decontaminated by circulating and cleaning at a relatively low temperature of 30-45°C for about one hour to react and remove the radioactive substances on the surface of the radioactive waste liquid evaporator, and then the radioactive waste liquid evaporator can be decontaminated and cleaned by rinsing with deionized water. It is simple and efficient, has low energy consumption, low cost, high economic benefits, has good prospects for use, and is worthy of application and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A morphological diagram of the appearance of a radioactive sample taken from the inner wall of a radioactive waste liquid evaporator provided in an embodiment of the present invention before decontamination;

[0026] Figure 2 This is a diagram of the appearance of a radioactive sample removed from the inner wall of a radioactive waste liquid evaporator after being decontaminated by the decontaminant provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The embodiment of the present invention provides a decommissioning decontaminant for a radioactive waste liquid evaporator, which comprises, by weight, 4-10 parts of an organic acid, 12-28 parts of an inorganic acid, 1-3 parts of a complexing agent, 3-6 parts of a sustained-release agent, 0.1-1.0 parts of a surfactant, and 50-85 parts of deionized water.

[0028] Wherein, the organic acid is one or more of ascorbic acid, oxalic acid, acetic acid and succinic acid.

[0029] Wherein, the inorganic acid is one or more of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid.

[0030] Wherein, the complexing agent is one or more of ethylenediaminetetramethylene phosphate sodium, diethylenetriaminepenta(methylene phosphonate), and ethylenediaminetetraacetic acid disodium.

[0031] Wherein, the sustained-release agent is one or more of polyaspartic acid, triethanolamine, sodium thioacetate and ammonium thioacetate.

[0032] Wherein, the surfactant is one or more of polyacrylamide, stearic acid, and sodium dodecylbenzene sulfonate.

[0033] The radioactive waste liquid evaporator is in contact with various radionuclides such as Co-60, Co-58, Sr-90 in the radioactive waste liquid for a long time. These radionuclides will be deeply attached to the inner wall of the radioactive waste liquid evaporator in the form of an oxide layer, and general methods such as acid washing cannot effectively remove them.

[0034] The decontaminant for decommissioning a radioactive waste liquid evaporator provided by the present invention has components that can fully react chemically with the oxide layer formed by the radioactive substances on the surface of the radioactive waste liquid evaporator, remove the oxide layer on the surface of the radioactive waste liquid evaporator, and achieve the purpose of chemical decontamination. The decontaminant has good decontamination performance, and the decontamination factor is as high as more than 100. Moreover, the components of the decontaminant are not easy to react with the radioactive waste liquid evaporator body, and the corrosiveness to the radioactive waste liquid evaporator is also small. The average corrosion depth of the decontaminant to the radioactive waste liquid evaporator during the decontamination process is less than 0.1um.

[0035] Furthermore, the decontamination agent for decommissioning a radioactive waste liquid evaporator provided by the present invention has components and reagents used in them that are all common industrial products, easy to purchase, cheap, with low comprehensive decontamination cost and high economic benefits, and each component is a non-toxic substance, safe and environmentally friendly.

[0036] The present invention provides a preparation method of a decontaminant for a radioactive waste liquid evaporator, wherein an organic acid is first added to a certain amount of deionized water, stirred for 5 to 15 minutes, and then an inorganic acid, a complexing agent, a sustained-release agent, and a surfactant are sequentially added after the organic acid is fully dissolved, and each reagent is stirred for 5 to 15 minutes, and the decontaminant for a radioactive waste liquid evaporator can be obtained after each component is fully dissolved. The preparation of the decontaminant can be completed in about one hour using deionized water at room temperature, and the method is simple, fast, and efficient.

[0037] The present invention provides a method for using a decontamination agent for a decommissioned radioactive waste liquid evaporator, comprising the following steps. The appearance of a radioactive sample taken from the inner wall of the radioactive waste liquid evaporator before decontamination is shown in FIG. Figure 1 shown.

[0038] Step 1) injecting the prepared decontaminant into the radioactive waste liquid evaporator, heating the decontaminant and using a centrifugal pump to circulate the decontaminant in the radioactive waste liquid evaporator for cleaning and decontamination.

[0039] Since the decommissioning decontaminant of the radioactive waste liquid evaporator provided by the present invention adopts a formula combining organic acid and inorganic acid, compared with organic acid, inorganic acid can directly release hydrogen ions and react chemically with the oxide layer on the surface of the radioactive waste liquid evaporator, thereby dissolving the oxide layer on the surface of the radioactive waste liquid evaporator, releasing the radioactive nuclides in the oxide layer, and strengthening the decontamination process. Moreover, since the decontaminant of the present application uses strong acid inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, in order to avoid excessive corrosion, the present application adds an appropriate amount of organic acid and corrosion inhibitor to the formula, so as to alleviate or control the corrosion rate to a certain extent, and avoid further corrosion of the radioactive waste liquid evaporator body. In addition, a small amount of surfactant is added to the formula, which helps to reduce the surface tension of the decontaminant and ensure that the decontaminant can better contact with the oxide layer on the surface of the radioactive waste liquid evaporator to promote the reaction between the oxide layer and the acid. At the same time, the present invention adds a small amount of complexing agent to the decontaminant formula, and the complexing agent can complex the radioactive nuclides released by the reaction to avoid its impact on the environment.

[0040] The decontaminant for decommissioning a radioactive waste liquid evaporator provided by the present invention has a specific reaction formula of chemical reaction during use as follows:

[0041] Oxide layer dissolution process: 2bH + +M a O b →aM(2b / a)+ +bH2O

[0042] Among them, M is a metal element, M a O b is the general chemical formula of the oxide film, H + is hydrogen ion, H2O is water molecule, M (2b / a)+ is the metal ion after the reaction.

[0043] Complexation process: M+EDTA→[M-EDTA],

[0044] Here, M is the radionuclide and [M-EDTA] represents the generated complex.

[0045] In order to facilitate the decontamination by reacting the decontaminant with the oxide film formed by the radioactive substances on the surface of the radioactive waste liquid evaporator, the decontaminant injected into the radioactive waste liquid evaporator is heated to 30-45°C to promote the decontamination reaction.

[0046] In order to reduce energy consumption, the waste heat of the radioactive waste liquid evaporator can be fully utilized to heat the decontaminant to 30-45° C. Of course, the heating device of the radioactive waste liquid evaporator itself can also be used to heat the decontaminant to 30-45° C.

[0047] At the same time, in order to promote the rapid progress of the decontamination reaction and to allow the decontaminant to fully react with the oxide film formed by the radioactive substances on the surface of the radioactive waste liquid evaporator, a centrifugal pump is used to circulate the decontaminant in the radioactive waste liquid evaporator at a flow rate of 1-3m / s for cleaning and decontamination.

[0048] In order to achieve a sufficient decontamination effect, the cleaning and decontamination time of the decontaminant in the radioactive waste liquid evaporator is controlled within 20 to 60 minutes.

[0049] Step 2) After the decontaminant cleaning is completed, the decontaminant in the radioactive waste liquid evaporator is emptied, and then the radioactive waste liquid evaporator is circulated and flushed with deionized water for 2-4 times to complete the decontamination cleaning of the radioactive waste liquid evaporator.

[0050] Among them, the appearance of the radioactive sample taken from the inner wall of the radioactive waste liquid evaporator after decontamination is shown in the figure below: Figure 2 shown.

[0051] from Figure 1 and Figure 2 It can be seen from the comparison that the radioactive sample of the radioactive waste liquid evaporator has an obvious black oxide layer on its surface before decontamination, while the oxide layer on its surface disappears after decontamination by the decontaminant provided by the present invention. This shows that the decontaminant provided by the present invention for the decommissioning of the radioactive waste liquid evaporator has achieved a good decontamination effect when decontaminating the radioactive waste liquid evaporator in the decommissioning stage.

[0052] The decontamination agent for decommissioning a radioactive waste liquid evaporator provided by the present invention and the method for using the same are specifically described below by way of examples.

[0053] Example 1

[0054] 1) The components selected in the embodiment of the present invention and the number of components added are shown in Table 1:

[0055] Table 1

[0056]

[0057]

[0058] 2) Chemical decontamination: Inject the decontaminant into the radioactive waste liquid evaporator, heat the solution to 35°C, and circulate the decontamination liquid using a centrifugal pump at a flow rate of 2.5m / s. The decontamination time is 30mins. After the decontamination is completed, drain the decontamination liquid and then rinse with deionized water to complete the decontamination.

[0059] The dosage of the contaminants on the surface of the radioactive waste liquid evaporator after decontamination by the decontaminant of the embodiment of the present invention was measured by using a portable surface contamination meter, and the mass loss of the radioactive waste liquid evaporator was obtained by an electronic balance. The decontamination factor and corrosion depth of the radioactive waste liquid evaporator were calculated as shown in Table 8.

[0060] Example 2

[0061] 1) The components selected in the embodiment of the present invention and the number of components added are shown in Table 2:

[0062] Table 2

[0063]

[0064] 2) Chemical decontamination: Inject the decontamination liquid into the radioactive waste liquid evaporator, heat the solution to 35°C, and circulate the decontamination liquid using a centrifugal pump with a flow rate of 2.5m / s. The decontamination time is 30mins. After the decontamination is completed, drain the decontamination liquid and then rinse with deionized water to complete the decontamination.

[0065] The dosage of the contaminants on the surface of the radioactive waste liquid evaporator after decontamination by the decontaminant of the embodiment of the present invention was measured by using a portable surface contamination meter, and the mass loss of the radioactive waste liquid evaporator was obtained by an electronic balance. The decontamination factor and corrosion depth of the radioactive waste liquid evaporator were calculated as shown in Table 8.

[0066] Example 3

[0067] 1) The components selected in the embodiment of the present invention and the number of components added are shown in Table 3:

[0068] Table 3

[0069]

[0070] 2) Chemical decontamination: Inject the decontamination liquid into the radioactive waste liquid evaporator, heat the solution to 35°C, and circulate the decontamination liquid using a centrifugal pump with a flow rate of 2.5m / s. The decontamination time is 30mins. After the decontamination is completed, drain the decontamination liquid and then rinse with deionized water to complete the decontamination.

[0071] The dosage of the contaminants on the surface of the radioactive waste liquid evaporator after decontamination by the decontaminant of the embodiment of the present invention was measured by using a portable surface contamination meter, and the mass loss of the radioactive waste liquid evaporator was obtained by an electronic balance. The decontamination factor and corrosion depth of the radioactive waste liquid evaporator were calculated as shown in Table 8.

[0072] Example 4

[0073] 1) The components selected in the embodiment of the present invention and the number of components added are shown in Table 1:

[0074] Table 4

[0075]

[0076] 2) Chemical decontamination: Inject the decontamination liquid into the radioactive waste liquid evaporator, heat the solution to 35°C, and circulate the decontamination liquid using a centrifugal pump with a flow rate of 2.5m / s. The decontamination time is 30mins. After the decontamination is completed, drain the decontamination liquid and then rinse with deionized water to complete the decontamination.

[0077] The dosage of the contaminants on the surface of the radioactive waste liquid evaporator after decontamination by the decontaminant of the embodiment of the present invention was measured by using a portable surface contamination meter, and the mass loss of the radioactive waste liquid evaporator was obtained by an electronic balance. The decontamination factor and corrosion depth of the radioactive waste liquid evaporator were calculated as shown in Table 8.

[0078] Example 5

[0079] 1) The components selected in the embodiment of the present invention and the number of components added are shown in Table 1:

[0080] Table 5

[0081]

[0082] 2) Chemical decontamination: Inject the decontamination liquid into the radioactive waste liquid evaporator, heat the solution to 35°C, and circulate the decontamination liquid using a centrifugal pump with a flow rate of 2.5m / s. The decontamination time is 30mins. After the decontamination is completed, drain the decontamination liquid and then rinse with deionized water to complete the decontamination.

[0083] The dosage of the contaminants on the surface of the radioactive waste liquid evaporator after decontamination by the decontaminant of the embodiment of the present invention was measured by using a portable surface contamination meter, and the mass loss of the radioactive waste liquid evaporator was obtained by an electronic balance. The decontamination factor and corrosion depth of the radioactive waste liquid evaporator were calculated as shown in Table 8.

[0084] Example 6

[0085] 1) The components selected in the embodiment of the present invention and the number of components added are shown in Table 1:

[0086] Table 6

[0087]

[0088] 2) Chemical decontamination: Inject the decontamination liquid into the radioactive waste liquid evaporator, heat the solution to 35°C, and circulate the decontamination liquid using a centrifugal pump with a flow rate of 2.5m / s. The decontamination time is 30mins. After the decontamination is completed, drain the decontamination liquid and then rinse with deionized water to complete the decontamination.

[0089] The dosage of the contaminants on the surface of the radioactive waste liquid evaporator after decontamination by the decontaminant of the embodiment of the present invention was measured by using a portable surface contamination meter, and the mass loss of the radioactive waste liquid evaporator was obtained by an electronic balance. The decontamination factor and corrosion depth of the radioactive waste liquid evaporator were calculated as shown in Table 8.

[0090] Example 7

[0091] 1) The components selected in the embodiment of the present invention and the number of components added are shown in Table 1:

[0092] Table 7

[0093]

[0094] 2) Chemical decontamination: Inject the decontamination liquid into the radioactive waste liquid evaporator, heat the solution to 35°C, and circulate the decontamination liquid using a centrifugal pump with a flow rate of 2.5m / s. The decontamination time is 30mins. After the decontamination is completed, drain the decontamination liquid and then rinse with deionized water to complete the decontamination.

[0095] The dosage of the contaminants on the surface of the radioactive waste liquid evaporator after decontamination by the decontaminant of the embodiment of the present invention was measured by using a portable surface contamination meter, and the mass loss of the radioactive waste liquid evaporator was obtained by an electronic balance. The decontamination factor and corrosion depth of the radioactive waste liquid evaporator were calculated as shown in Table 8.

[0096] Table 8

[0097]

[0098]

[0099] It can be seen from Table 8 that the decontamination agents for the decommissioning of the radioactive waste liquid evaporators of Examples 1-7 of the present invention have excellent decontamination performance, with a decontamination factor as high as over 100.

[0100] Furthermore, the decontaminant used in the decommissioning of the radioactive waste liquid evaporator of Examples 1-7 of the present invention has low corrosivity, and the average corrosion depth of the radioactive waste liquid evaporator is less than 0.1 um.

[0101] Therefore, when the decommissioning decontaminant for radioactive waste liquid evaporator provided by the present invention is used to decontaminate the radioactive waste liquid evaporator in the decommissioning stage, the components of the decontaminant can fully chemically react with the oxide layer formed by the radioactive substances on the surface of the radioactive waste liquid evaporator to remove the oxide layer on the surface of the radioactive waste liquid evaporator, and the decontamination factor thereof is as high as more than 100, so the decontamination agent has good decontamination performance and can achieve a good chemical decontamination purpose.

[0102] Moreover, when the decontaminant is used to decontaminate the radioactive waste liquid evaporator in the decommissioning stage, its components are not easy to react with the radioactive waste liquid evaporator body, and are less corrosive to the radioactive waste liquid evaporator. Ultimately, the average corrosion depth of the radioactive waste liquid evaporator is below 0.1 um.

[0103] At the same time, in the process of decontamination of the radioactive waste liquid evaporator reaction in the decommissioning stage, the complexing agent in the decontamination agent formula can complex the radioactive nuclides released by the reaction to avoid the impact on the environment, not only the amount of waste generated is small, but also other toxic substances will not be generated. Moreover, the decontamination agent components of the present invention and the waste generated after decontamination do not contain harmful ions that affect the wastewater treatment system, have good compatibility with the wastewater evaporation treatment system, have little impact on the environment, are safe, non-toxic, and green and environmentally friendly.

[0104] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A decontaminant for a radioactive waste liquid evaporator, characterized in that: In terms of mass fraction, the detergent comprises 4-10 parts of organic acid, 12-28 parts of inorganic acid, 1-3 parts of complexing agent, 3-6 parts of sustained-release agent, 0.1-1.0 parts of surfactant and 50-85 parts of deionized water.

2. The decontaminant for decommissioning a radioactive waste liquid evaporator according to claim 1, characterized in that: The organic acid is one or more of ascorbic acid, oxalic acid, acetic acid and succinic acid.

3. The decontamination agent for decommissioning a radioactive waste liquid evaporator according to claim 1, characterized in that: The inorganic acid is one or more of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid.

4. The decontamination agent for decommissioning a radioactive waste liquid evaporator according to claim 1, characterized in that: The complexing agent is one or more of ethylenediaminetetramethylene phosphate sodium, diethylenetriaminepenta(methylene phosphonate) and ethylenediaminetetraacetic acid disodium.

5. The decontamination agent for decommissioning a radioactive waste liquid evaporator according to claim 1, characterized in that: The sustained-release agent is one or more of polyaspartic acid, triethanolamine, sodium thioacetate and ammonium thioacetate.

6. The decontamination agent for decommissioning a radioactive waste liquid evaporator according to claim 1, characterized in that: The surfactant is one or more of polyacrylamide, stearic acid and sodium dodecylbenzene sulfonate.

7. A method for preparing a decontaminant for a decommissioning radioactive waste liquid evaporator according to any one of claims 1 to 6, characterized in that: include: The organic acid is added to the deionized water, stirred for 5 to 15 minutes, and then the inorganic acid, complexing agent, sustained-release agent and surfactant are added in sequence, and each time a reagent is added, the mixture is stirred for 5 to 15 minutes.

8. A method for using the decontamination agent for decommissioning a radioactive waste liquid evaporator according to any one of claims 1 to 6, characterized in that: The steps include: injecting a decontaminant into a radioactive waste liquid evaporator, heating the decontaminant, and using a centrifugal pump to circulate the decontaminant in the radioactive waste liquid evaporator for cleaning and decontamination; After cleaning with the detergent, the detergent in the radioactive waste liquid evaporator is drained, and then the radioactive waste liquid evaporator is circulated and flushed with deionized water.

9. The method for using the decontaminant for decommissioning a radioactive waste liquid evaporator according to claim 8, characterized in that: The temperature of the decontaminant after being heated in the radioactive waste liquid evaporator is 30-45° C., and the flow rate of the decontaminant circulating in the radioactive waste liquid evaporator is 1-3 m / s.

10. The method for using the decontamination agent for decommissioning a radioactive waste liquid evaporator according to claim 9, characterized in that: The cleaning and decontamination time of the decontaminant in the radioactive waste liquid evaporator is 20 to 60 minutes.

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