Gel Synthesis And Decontamination Of Metal Surface Radioactive Pollution

With the increasing application of nuclear technology,radioactive pollution will also occur,which poses a huge challenge to the radiation safety of operation and maintenance personnel and public safety.Decontamination is one of the important means to solve the pollution problem.Inappropriate decontamination methods will increase a large amount of secondary waste and will cause waste volume reduction,storage,and management issues.Traditional mechanical and physical decontamination is likely to cause aerosol pollution and form secondary waste that is not easy to collect.The electrochemical decontamination method is more careful about the size of the decontamination object,and it is easy to cause the decontamination components to partially dissolve,which has limitations for non-conducting components.So,the demand for efficient and easy-to-use decontamination methods is becoming more urgent.In this paper,four common colloids of polyvinyl alcohol,polyacrylamide,sodium carboxymethyl cellulose and sodium polyacrylate are used as the gel matrix,combined with four detergents acidic potassium permanganate,alkaline potassium permanganate,acidic Cerium sulfate and acid silver nitrate are used to prepare the decontamination gel.Through the decontamination of the metal surface contaminated with radioactivity to explore the optimal formulation of various colloids.Due to the needs of the project,the strippable formula used in the thermal chamber of the nuclear power plant for radioactive decontamination has achieved good results.The experiment also explored the relationship between the decontamination rate of gel decontamination and time as well as the influence of temperature.The anti-corrosion research of metal samples after decontamination was carried out by electrochemical means.The main conclusions in the study are as follows:(1)In the polyvinyl alcohol gel system,the gel forms a peelable film after drying,which is convenient for peeling.When the detergent is acid potassium permanganate,the decontamination rate is 92.7%;when the detergent is alkaline potassium permanganate,the decontamination rate is 92.8%;when the detergent is acid sulfuric acid,When it is cerium,its decontamination rate is up to 94.9%;when the detergent is acid silver nitrate,its decontamination rate is up to 82.8%;the best decontamination gel detergent is acid cerium sulfate,the formula is the glue content It is 16%,the content of ceric sulfate is 0.21%,and the content of nitric acid is 0.9%.(2)In the polyacrylamide gel system,when the detergent is acid potassium permanganate,the decontamination rate is 52.9%;when the detergent is alkaline potassium permanganate,the decontamination rate is the highest 92.8%;when the detergent is acidic cerium sulfate,its decontamination rate is up to 98%;when the detergent is acidic silver nitrate,its decontamination rate is up to 95.4%;considering the comprehensive cost of decontamination and Decontamination efficiency,the best decontamination gel detergent is acid cerium sulfate,polyacrylamide gel content is 25%,cerium sulfate content is 0.63%,sulfuric acid content is 3.5%,the formula decontamination rate is 94.7 %.(3)In the sodium carboxymethyl cellulose gel system,when the detergent is acidic potassium permanganate,the decontamination rate is 71% at the highest;when the detergent is alkaline potassium permanganate,the decontamination rate is The highest decontamination rate is 58.4%;when the detergent is acidic cerium sulfate,the highest decontamination rate is 90.8%;when the detergent is acidic silver nitrate,the highest decontamination rate is 62%;Gel detergent is acidic cerium sulfate,the formula is 9% gel content,cerium sulfate content is 0.072%,sulfuric acid content is 0.48%.(4)In the sodium polyacrylate gel system,when the detergent is acid potassium permanganate,the decontamination rate is up to 86%;when the detergent is alkaline potassium permanganate,the decontamination rate is the highest 65.4%;when the detergent is acidic cerium sulfate,its decontamination rate is up to 84%;when the detergent is acidic silver nitrate,its decontamination rate is up to 57%;acidic potassium permanganate and acid The decontamination efficiency of the two detergents of ceric sulfate is comparable,but the acid potassium permanganate gel is easy to oxidize and discolor the metal surface.Therefore,the optimal formula for selecting the detergent is acidic cerium sulfate.The formula is 30% gel content,0.12% cerium sulfate content,and 0.24% nitric acid content.(5)In the study of gel decontamination rate and temperature,only sodium polyacrylate gel performed slightly better at high temperature,and the final decontamination rate of other gels was basically independent of temperature.However,the influence of temperature is reflected in the decontamination time.When the temperature is higher,the necessary decontamination time is significantly shortened,and when the temperature is lower,the necessary decontamination time is longer.(6)The polarization curves before and after decontamination of metal samples were measured by electrochemical means.The corrosion resistance of metal samples after decontamination of PVA gel was significantly improved;the corrosion resistance of polyacrylamide gel was basically unchanged after decontamination;Carboxymethyl The base cellulose sodium gel has improved corrosion resistance after decontamination.