Decontamination of radioactive soils
Development of methods and technology for decontamination of radioactive Cs-containing soils by special polymeric systems
Tech Area / Field
- CHE-IND/Industrial Chemistry and Chemical Process Engineering/Chemistry
- CHE-POL/Polymer Chemistry/Chemistry
- ENV-RWT/Radioactive Waste Treatment/Environment
3 Approved without Funding
Yerevan Institute "Plastpolymer", Armenia, Yerevan
- Scientific and Production Center "Armbiotechnology" NAS RA, Armenia, Yerevan\nNational Nuclear Center of the Republic of Kazakstan / Institute of Radiation Safety and Ecology, Kazakhstan, Kurchatov
- Graduate School of Frontier Biosciences Osaka University, Japan, Osaka\nUS Environmental Protection Agency EPA, National Homeland Security Research Center, USA, OH, Cincinnati
Project summaryThe Project aim
· Synthesis of polymer systems with special parameters that enable to bind radioactive Cs in clay minerals (montmorillonite, illite, vermiculite).
· Creation of the newest compositions for soil decontamination - multifunctional "fungi + polymers" ("polyfungi") systems.
· Development of technology for soil decontamination with uses of special polymers and "polyfungi" compositions
The main stages of research, findings and conclusions throughout the project A-2071 are presented in the Summary, published in JAEA-Conf 2016-002 http://jolissrch-inter.tokai-sc.jaea.go.jp/search/se rvlet/search?5055495 The main findings are as follows:
It was discovered for the first time a redistribution of radioactive Cs between soil layers due to capillary and gravitational movements of polymer solutions in soil. This phenomenon is revealed only under influence of certain polymer systems.
The observed regularities were the basis for development of methods for soil decontamination. The main principle is that Cs is included into polymer solutions and transported from one part of soil to others. Thereby a part of soil is enriched with radioactive Cs at the expense of depletion others. The part of soil with the lower activity should be separated from soil with the higher activity and returned to fields.
The principal types of polymeric systems and parameters responsible for Cs binding were determined. Some samples of polymer systems with new properties enabling to bind and move radioactive Cs in radiation-contaminated soils were synthesized and tested.
The discovered phenomenon has been tested in several series of experiments at ANPP on 137Cs-contaminated soils. Under conditions of the carried experiments percent of 137Cs redistribution reached 30-32 and 40-42% depending on type of clay mineral in the soils (illite and montmorillonite respectively). Repeatability of these results leads to conclusions that there are thresholds of Cs extraction from different clay minerals. In that context, some our previously made observations and a few preliminary experiments suggest that the microscopic soil fungi (MSF) in mixture with the polymer solutions may facilitate more complete Cs extraction from soils.
In the proposed new Project the following will be done:
-Polymeric systems will be developed with the most optimal parameters to bind and transport the maximum amount of Cs in soils.
-Multifunctional ability of fungi will be studied, such as: to adjust viscosity and morphology of polymer solutions; to improve the efficiency of 137Cs extraction from soils; to promote biodegradation of polymers in the soil with time.
-All experiments with radioactive soils will be done at the Armenian NPP. The obtained results will be verified at the IRSE on soils of Semipalatinsk Test Site, contaminated with different radionuclides. Methods for radioactive soils decontamination will be developed
Expected Results and Their Application The proposed project belongs to categories applied research and development.
Applied research. The implementation of this Project will yield the following results:
The optimum parameters of polymeric systems to bind radioactive Cs in soils of different mineralogical composition and jointly move through capillaries and pores will be determined. Technology for polymers synthesis will be designed.
Study and revealing of all positive functions of MSF in complex with polymers for soil decontamination will promote a creation of new multifunctional systems “polymers + fungi” (polufingi) aimed at remediation of radioactive Cs containing soils.
The findings of the proposed new researches are expected to be used in technologies of decontamination of various other objects, in particular for remediating radioactive soils at and around Semipalatinsk Test Site.
Development. The major development outcomes will be technology for synthesis of special grades of polymeric systems with new properties to be used for radioactive soils decontamination, and also the new compositions “polymers + fungi”
The results can be used in Japan for decontamination and minimization of radioactive soil wastes, collected into bags and stored at the storage sites after the Fukushima NPP accident.
Meeting the ISTC goals and objectives The Project will allow scientists that were earlier engaged in weapons development, to carry out scientific research for peaceful purposes. The Project includes applied researches and development of new polymeric materials for peaceful purposes (deactivating polymeric systems and compositions for environmental protection and nuclear safety).
Scope of activities. The following activities will be implemented under the Project:
- · Synthesis of polymers with special parameters and study of their functional content as well as properties of solutions/dispersions.
· Examination of mixtures of polymers solutions with MSF (characteristics-properties). Study of effects of mixture (polymers + MSF) on redistribution efficiency of 137Cs in soils with MMT, illite, vermiculite.
· Verification of the developed decontamination methods at the IRSE and on soils with radioactive contaminations at Semipalatinsk Test Site