Research on nuclear emergency decontamination technology based on strippable coating

Rheological and radioactive decontamination properties of ethyl cellulose sols in green solvents at a temperature below 0 °C

Strippable film decontamination has been considered one of the best prospects for radioactive surface decontamination due to its high decontamination effect and less secondary pollution. However, research into strippable films has until now focused on radioactive decontamination at room temperature. Therefore, it is vital to seek a suitable degradable material for preparing strippable films in removing contaminants in an extremely cold region, as it will face the problem of the freezing of the detergent. Ethyl cellulose (EC) is a kind of degradable biopolymer which is easily dissolved in volatile green organic solvents to form a sol below 0 °C which is advantageous for forming a film. Therefore, it would be the best choice for preparing a strippable film detergent. In this study, EC sols were obtained by placing EC powder into the green solvents anhydrous ethanol and ethyl acetate. The steady and dynamic rheological behavior of EC sols was investigated with a rotary rheometer with the temperature ranging from -10 °C to 0 °C to disclose their spraying performance. Moreover, the radioactive decontamination effect of EC sols and the mechanism were also investigated. The results showed that the EC sols were pseudoplastic fluids which obeyed the Ostwald-de Waele power law below 0 °C. Furthermore, the viscosity of EC sols could be reduced by stirring, which is convenient for large-area spraying during decontamination below 0 °C. At -10 °C, the comprehensive decontamination rates of all plates were over 85%. Therefore, EC sols could be used as a basic material for strippable film decontamination below 0 °C.

Radioactive decontamination in low-temperature environments by using a novel high-strength strippable coating

Accidents involving nuclear leakage and radioactive source diffusion will result in a substantial amount of radioactive pollution, posing a threat to the world's environment as well as human safety. To get rid of the pollution, this work describes a new type of strippable detergent coating designed to remove radioactive contamination, especially in low-temperature conditions. In situ polymerization was employed to make EC/PUA/PVAc detergent from degradable ethyl cellulose (EC), tea polyphenols (TP), and polyvinyl acetate (PVAc), and polytetramethylene ether glycol bis-para-aminobenzoate (P1000). The film-forming performance, decontamination efficiency, and mechanical properties of the decontamination coating formed by the detergent were studied. Designed to work in a low-temperature environment, the detergent can be sprayed and peeled to remove surface radioactive staining. A universal material testing machine was used to assess the low-temperature rheometry, SEM, EDX, FT-IR, and other variables and to characterize the decontamination coating and the decontamination mechanism of the detergent. At -10-10 °C, the EC/PUA/PVAc detergent has good fluidity and sprayability and forms a strippable coating. The tensile strength of the decontamination coating can be as high as 26.4 MPa, and its 180° peel strength on ceramic tile, glass, stainless steel, cement, marble are 0.49 ± 0.08 N/m, 1.82 ± 0.41 N/m, 3.03 ± 1.65 N/m, 35.60 ± 1.17 N/m, 44.43 ± 4.10 N/m, respectively. The decontamination factors ranged from 3.32 to 10.02, with a decontamination rate above 85%.

Aqueous Strippable Polymer Coating for Highly Efficient Primary Radioactive Uranium Decontamination with Versatility on Diversified Surface

The decontamination of radioactive materials on the surfaces of nuclear facilities has generated large quantities of waste from the rapid development of the nuclear industry, posing a potential threat globally. Strippable coating has been employed for some time to remove radioactive contamination due to its high performance and removability, flexibility, and compatibility with various substrates. Herein, an aqueous strippable coating based on an adsorbent/polyvinyl alcohol (PVA) polymer was developed to remove radioactive uranium from stainless-steel surfaces that showed greater decontamination than that of DeconGel, with an efficiency of 87.2% for 5 g/L uranium and 95.5% for 22.5 g/L uranium, along with a high repeatability and better mechanical properties. Furthermore, the prepared coating was versatile and could be applied to a range of substrate surfaces (lacquered, aluminum, glass, plastic, and ceramic), with outstanding performance ranging from 79.2 to 95.4% for 1 g/L uranium. The prepared coating could also be applied through brushing or spraying to horizontal or vertical substrates. The exceptional performance could be due to the synergistic effect of the introduction of ethylene diamine tetra-acetic acid disodium salt (EDTA-2Na) as a chelating agent and the nano-adsorbent CaCO₃/TiO₂.

A State-of-the-Art Review of Radioactive Decontamination Technologies: Facing the Upcoming Wave of Decommissioning and Dismantling of Nuclear Facilities

The average share of nuclear energy in electricity production is expected to increase under the background of the global pursuit towards carbon neutrality. Conjugating with its rapid development, the wave of decommissioning and dismantling (D&D) of nuclear facilities is coming. The surface decontamination is a prerequisite to D&D, which will make it easier and reduce the volume of radioactive wastes. However, there are no comprehensive studies on the decontamination methods, which is not helpful for the sustainable development of nuclear energy and environment protection. Therefore, in this work, the current status and future trends of global energy and nuclear energy are first analyzed. Then, various decontamination approaches are comparatively studied, including cleaning mechanisms, application subjects, and intrinsic advantages and disadvantages. Finally, the criteria and factors for selecting a decontamination process, the challenges, and future studies are directed. Among the mechanical methods, laser-based cleaning is high-speed, having automation ability, and thus is promising, although it creates a dust and airborne contaminant hazard. In further studies, factors such as selecting a proper laser facility, optimizing operating parameters, and designing a high-efficiency dust collection system could be studied. Regarding the chemical method, chemical gels are good for decontaminating complex shapes and vertical and overhead surfaces. In addition, they can enhance other decon agents’ efficiency by improving contact time. However, the formulation of colloidal gels is complex and no gel type is useful for all contaminants. Therefore, novel and versatile gels need be developed to enlarge their application field. Combining various decontamination methods will often have better results and thus a reasonable and effective combination of these decontamination methods has become the main direction.