Experience of applying of deactivating polymeric films in the Chernobyl promoted elaboration of different deactivating polymeric compositions, due to their main advantages (as compared with other methods of deactivation) such as a small amount of solid waste and exclusion of liquid radioactive waste requiring additional secondary processing.
However, despite the fact that some of mentioned compositions are included in list of decontamination means, many publications and discussion at different seminars and workshops show that they are not yet widely used.
Moreover, analysis of the huge scope of deactivations works, which is being conducted around Fukushima, reveals the urgency of newer deactivations approaches and means.
The proposed new Project includes the complex of works for advancement of developed technologies and samples of the deactivating polymeric systems in view of the newer deactivating challenges, which are highlighted after the Fukushima NPP accident.
Project goals and objectives
- Optimization of already developed polymeric systems in view of their wide application for deactivation of different type of surfaces, in indoor and outdoor situation under different environmental conditions.
- Examination of developed copolymers for decontamination of radionuclide 134Cs and 137Cs on soil;
- Modifications of polymers systems to achieve this goal;
- Study an effect of combining of copolymers with microscopic soil fungi (MSF) on radionuclide fixation;
- Engineering of technical documentation for methods of copolymers synthesis and their tests at laboratory scale.
Proposed methodology and outline of R&D plan
- Synthesis of (co) polymers through methods of radical copolymerization in the water and water-dispersion medium by using of various initiating systems (red-ox, ATRP).
- Determination of characteristics and properties of the obtained (co) polymers (functional composition, molecular weights, viscosity, рН, etc.) by using of methods of the chemical analysis, IR-, NMR-, UV-spectroscopy, viscosimetry.
- Study of water solutions (viscosity/Brookfield/, the size of particles and high-molecular formations depending on concentration, surface tension, critical concentration of micelle formation, limiting wetting angle /CAM-101/).
- Study of mechanism of removing Cs from different surfaces depending on polymer functionality, range of viscosities, type of polymeric systems (solutions, dispersions). - Definition of film-forming properties of polymer solutions, dispersions and compositions (duration of film formation, thickness, strip ability from various surfaces, etc.) depending on environment conditions (temperature, humidity)
- Estimation of deactivating properties of samples at Armenian NPP (different surfaces, mainly porous, and soils).
- Elaboration and using of detailed methodology of experiments with MSF in view of specificity works with both radionuclides and micro fungi.
- Evaluation of technological options with respect to the scale-up of the processes.
- Selection of samples of polymeric systems with optimum properties and technologies, providing these properties for further expanded tests in corresponding laboratories.
Potential impact of expected results on state of art
Outcomes of implemented works supposed to be new advanced polymeric systems and technological methods, providing their advanced properties.
These products will expand the range of decontaminating polymeric systems that will be contributes to the solution of specific problems of decontamination.
The basic monomer units for synthesis of developed copolymers are vinyl monomers, in particular industrial monomer vinylacetate. In production of this monomer and all range of its copolymers, Japan is the leading country with companies around the world.
Technologies being developed, that provide new decontaminating properties of polymer systems, are close to industrial technologies used for the synthesis of such type of polymers.
Hence to the end of the Project an assessment of the optimal samples and technologies need to be done joint with Japanese specialists in view of possibility to transfer technologies from laboratory to pilot scale.
Contribution of the proposed work to the problems in and around Fukushima
1. Strippable coverings
Judging by information from different sources (JAEA reports, articles, papers), to date all possible variants for decontamination of polluted areas are being used and tested at Fukushima.
Deactivation of residential areas includes a large number of objects and variety of surfaces; to reduce a level of radioactivity basically high-pressure water (and partially-pilling methods) is used.
Polymeric materials are used both for deactivation of residential areas as absorbing materials, strippable coatings and as solidification agent at soils decontamination.
Therefore, further elaboration and examination of the copolymers systems in enhanced tests with using of different type of surfaces, in indoor and outdoor situation under different environmental conditions will allow reducing the volume of liquid radioactive waste in cases of using of strippable deactivating coverings instead of water methods.
2. Soil decontamination
To date several methods of soil decontamination are described depending on contamination level:
- Removing of highly-contaminated soil as radioactive wastes; for reduction of the amount of wastes a solidification agent are used to control thickness of the surface layer to be removed off.
- Sorting of the removed soil to separate off parts with high- and low-activity; this method is practiced both at solid wastes storage facilities and yet on farmland. In the last case after soil separation the low- activity part is returned to its place.
- Stripping off contaminated topsoil and exchange it with subsoil.
Based on this information, it is expected, that outcomes of the project will be able to contribute in soil decontamination in several cases:
- To fix the radionuclides in soil to prevent dissemination at the expense of creating accumulating and retaining polymer layer.
- To concentrate the radionuclides into narrow layer of soil before soil wastes removing. This method will affect an efficiency of separation of soil with high-level and low-level activities yet on farmland.
- Analogical approach will be able to use for decontamination of removed soil wastes.
Benefits from MSF as part of deactivating systems will be revealed under Project implementation because these experiments will be undertaken for the first time.
