Ukrainian scientists develop surface radiation-removal device
A group of Ukrainian scientists has developed a method that allows electrochemical removal of radiation from contaminated surfaces, the official website of the National Academy of Sciences of Ukraine reports.
The research was conducted by scientists from the V.I. Vernadsky Institute of General and Inorganic Chemistry of the National Academy of Sciences of Ukraine. After testing, the group created a device for electrochemical decontamination of metal surfaces of equipment and developed documentation for the serial use of such a device.
Why do we need such a device?
Ukraine is developing its own nuclear power industry and will do so in the future. Equipment of nuclear power plants and experimental reactors (heat exchange equipment, pipelines, etc.) gets contaminated during operation with radionuclides and can be dangerous for the operating personnel.
“Considering the events that took place at the Chernobyl nuclear power plant in 1986, the problem of decontamination of technological equipment in Ukraine is even more acute than in any other country in the world,” writes the National Academy of Sciences.
Radionuclides (atoms with unstable nuclei) accumulate mainly in defects: microcracks, depressions of the surface of equipment formed by oxide compounds (the thickness of such a layer is estimated at about 50 μm). Such radionuclides can be removed mechanically, chemically, and electrochemically.
Of these methods, according to the National Academy of Sciences, only the electrochemical one ensures the preservation of the initial shape, size, and quality of surface treatment.
How does it work?
Electrochemical decontamination works in the following way: the surface layer of contaminated equipment is destroyed by the electric current (direct, alternating current, and alternating polarity). The elements that make up the contaminated layer are converted into compounds. They accumulate in the solution used in the process.
The National Academy of Sciences notes that the known methods of electrochemical removal of radionuclides under immobile conditions are almost unsuitable for the decontamination of large equipment. This requires custom large baths to fit the equipment. Also, in this case, radionuclides are not removed from the inner surfaces.
A group of Ukrainian scientists has developed a device that eliminates such shortcomings. The essence of the development is that the contaminated surface is connected to the positive pole of a direct current source (or made one of the electrodes if the alternating current is used). The cathode is moved over the surface, which contacts the anode through a layer of porous dielectric saturated with a solution: with its help, radionuclides are removed from the surface. The scheme of operation of the device for external and internal surfaces looks like this:
Scientists have developed an external electrode (cathode) that is attached to a telescopic rod. It also has devices mounted on it that ensure the current supply, solution to the dielectric, and movement along the graded surface. Such a scheme also means that maintenance personnel should not come into contact with the contaminated surface when cleaning it.
During electrolysis, radionuclides go into solution and accumulate in the porous material. Unlike immobile cleaning methods, this method allows decontaminating equipment without dismantling it. In contrast to decontamination in immobile baths, in this case, the volume of solution with radionuclides is small.
The research team has already tested this equipment together with scientists from the Research Nuclear Reactor of the Institute for Nuclear Research of the National Academy of Sciences.