Nuclear decontamination - project proposal

Immobilization of Radionuclides in Stable Unleachable Phases by Application of Ultrasound-Modified Cation Exchanged Zeolite


We wish to establish strategic project partnerships for the development of atomic energy projects related to the safe decontamination and passivation of radionuclides in water. MPI Ultrasonics has extensive experience with ultrasonic liquid-processing units and technology, including customized design and applications experience using “MMM Ultrasonic Technology”. Vinča Institute for Nuclear Sciences has wide-ranging expertise in Radionuclides and Material science, both theoretical and laboratory work. Together we are ready to address large-scale polluted water decontamination caused by accidents in nuclear power plants.

Project summary


One of the most serious consequences of the Fukushima Daiichi nuclear disaster was the leakage of radioactive contaminated water and the continuing risk of groundwater contamination. As a result, there has been an increased focus on nuclear safety and particularly on the safe and efficient solidification or immobilization of radioactive waste. Two isotopes of particular importance are Caesium-137 and 134 (137Cs and 134Cs), the main fission products in radioactive waste from industrial as well as research applications. It is of paramount importance to develop technology that will effectively remove these and other radioisotopes (radionuclides) from the contaminated water, safely store it and prevent from entering soil and groundwater.

Seven years after the accident in Fukushima an extremely large amount of contaminated water and soil still needs to be properly treated and stored, despite the series of drains and underground barriers that have been built. Currently about one million tons of water is being held in 1000 tanks and the volume grows by 100 tons a day. These large accumulations of contaminated water represent a continuing threat to health and safety, particularly during earthquakes and typhoons.

One of the most effective methods for the treatment and disposal of radioactive wastes has been based on ion-exchanged zeolites. Zeolite, either natural or synthetic, is an aluminosilicate compound with three-dimensional cage-structure. It shows high resistance to radioactive irradiation and high affinity for cations (such as Cs) at the same time. Different approaches were applied in order to avoid leaching of radioactive cations from zeolite saturated with radionuclides. A number of studies suggest that a phase transformation of radionuclide saturated zeolite, where radionuclide is embedded into the structure of the new phase is a viable route for achieving the safe disposal of radioactive waste.

A new phase, such as pollucite, is one of the most stable phases under depository conditions and is a preferable phase for Cs immobilization because it has an appropriately sized channel. After the formation of pollucite, Cs cannot exit the pollucite spatial framework without breaking it. Methods developed to date for the safe trapping of cesium into pollucite structure all require high temperature processing between 700 ̊C to 1000 ̊C. After ion exchange and adsorption of Cs within the zeolite structure, followed by phase transformation, blocking of the Cs ions is fully achieved and this prevents subsequent leaching of Cs when zeolite is in contact with water.

Project Objective

Our objective is to design a safe, economical and easy method for the immobilization of radioactive isotopes while minimizing the need for high-temperature processing. The following techniques are proposed:

  • Ultrasonically stimulated, accelerated micro encapsulation, agglomeration and precipitation of radioisotopes in zeolites, as well as microcrystallization, phase transformation (recrystallization) into unleachable zeolitic structure.
  • If necessary hot pressing will be further applied.
  • Ultrasound induced transformation of cation (Cs) exchanged zeolite may transform radioisotope saturated zeolite structure into new, stabile phase as a final storage option for long-term disposal in a geological repository.
  • The process of high thermal transformation may be substituted by using ultrasound-assisted synthesis allowing formation of pollucite at lower temperatures.

This represents the most promising, simple and safe route for the permanent disposal of radionuclides with low energy consumption and easy manipulation of radioactive material.

The simultaneous application of ultrasound and sorption may provide an efficient way to immobilize radioactive ions by their incorporation into a crystal lattice of stable compounds.

Using the same technology as described above, other materials such as clays, carbon matrices and their composites may be used as alternatives to zeolites as sorption media.

Further, tritium is a byproduct of nuclear operations and water contaminated with tritium is currently the major issue at the Fukushima power plant 7 years after the accident. An additional aim of the project therefore will be to investigate the possibility of ultrasound encapsulation of tritium into zeolites or other matrices, some of which have also proven to be good molecular sieves for tritium.

The use of ultrasonic processing detailed above has not been investigated or applied before. Simultaneous use of these techniques opens new possibilities in creating new reaction mechanisms for removing radioactive isotopes from contaminated water. The proposed approach may lead to a new solution that is easy, fast, inexpensive, non-invasive and safe. Due to the existence of a large number of sites with existing or threatened contamination, the development of such improved methods represents an urgent need.


  • Specific material matrices coupled with specialized ultrasound equipment will be designed depending on the system needed to be purified.
  • Detailed investigation of different zeolite sand clays as matrices for ion exchange of different radionuclides can be used to synthesize stabile radioactive cation exchanged aluminosilicate phases.
  • A series of synthesis optimization steps will be followed by microstructural and morphological characterization using XRD, XRF, FTIR, SEM, porosity as well the test of leachability will be performed.
  • Experimental simulations of the whole process and pilot plant will be performed.


A team of experts can be assembled along with dedicated laboratories, ultrasonic processing equipment and operational technology, after the completition of necessary conditions between interested partners.

Key technologies

  • Radioactive and wastewaters decontamination
  • Ultrasonically optimized micro encapsulation in liquids
  • Ultrasonically accelerated agglomeration and precipitation of solids in liquids
  • Ultrasonically stimulated and accelerated micro-crystallization
  • Ultrasonically assisted and accelerated chemical synthesis and oxidation
  • Synergism of simultaneous use of sorption and sonication phenomena
  • Additives and chemistry for stimulating of radionuclides precipitation in water
  • Immobilization and safe disposal of fission related radioactive elements
  • Ultrasonically injected ozone in water (chemical and bacteriological neutralization)

Our Facilities, Technology and Infrastructure (web links)

Some references related to the proposed project

  1. M. Omerašević, J. Ružić, B. Nedić Vasiljević, Z.Baščarević, D. Bučevac, J. Orlić, Lj. Matović - Transformation of Cs-exchanged clinoptilolite to CsAlSi 5 O 12 by hot-pressing, Ceramics international, 2017, In Press
  2. M. Omerašević, Lj. Matović, J. Ružić, Ž. Golubović, U. Jovanović, S. Mnetus, V. Dondur - Safe trapping of cesium into pollucite structure by hot-pressing method, Journal of Nuclear Materials 474 (2016) 35-44
  3. Lj. Matović, A. Đukić, M. Omerašević, K. Kumrić, O. Rosskopfová, A. Hamárová and P. Rajec - Removal of pertechnetate from aqueous solution using activated pyrolytic rubber char, Journal of Radioanalytical and Nuclear Chemistry, 2017, In Press
  4. Đ. Petrović, A. Đukić, K. Kumrić, B. Babić, M. Momčilović, N. Ivanović, Lj. Matović - Mechanism of sorption of pertechnetate onto ordered mesoporous carbon, Journal of Radioanalytical and Nuclear Chemistry, October 2014, Volume 302, Issue 1, pp 217-224, DOI :10.1007/s10967-014-3249-0
  5. P. Bosch, D. Caputo, B. Liguori, C. Colella - Safe trapping of Cs in heat-treated zeolite matrices, Journal of Nuclear Materials 324 (2004) 183-188
  6. G.D. Gatta, N. Rotiroti, T.B. Ballaran, C. Sanchez-Valle, A. Pavese - Elastic behavior and phase stability of pollucite, a potential host for nuclear waste, American Mineralogist 94 (2009) 1137-1143
  7. D.Demange, O.Borisevich, N.Gramlich, R.Wagner, S.Welte - Zeolite membranes and palladium membrane reactor for tritium extraction from the breeder blankets of ITER and DEMO, Fusion Engineering and Design (88) 9-10 (2013) 2396-2399
  8. Tim Hornyak, March 9, 2018 (Tim Hornyak). Clearing the Radioactive Rubble Heap That Was Fukushima Daiichi, 7 Years On

About the partners

MPI Ultrasonics

MP Interconsulting is a Swiss company with a range of innovative new developments in power ultrasonics, offering standard and custom-built ultrasonic systems for a wide range of applications including sonochemistry, liquid processing (mixing and homogenization, including liquid metals) sterilization, heavy duty ultrasonic cleaning, high intensity atomizers (cold spray and vapour sources), metal atomizers, surface hardening, impregnation and coating, material aging and stress relieving, ultrasonically-assisted extrusion of plastics and metals, founding and casting (vacuum casting, homogenization, degassing) and many other new and unusual processes.

Department of Materials Science, Vinča Institute for Nuclear Sciences

The Department of Material Science has a qualified staff (more than 30 of whom have a PhD in Material science), the necessary infrastructure and instruments to proceed with the synthesis, modification and characterization of various types of materials: metals, ceramics, carbon materials, composites, etc. A large number of scientific projects, both at the national and international level, are carried out by the Departments’ associates. Cooperation with the industry is realized through the services of determination of composition, microstructural, mechanical and morphological properties of different kind of materials; consulting services; as well as feasibility studies for remediation of contaminated sites and waste materials. Furthermore, the national center of excellence "Center for the synthesis, processing and characterization of materials for use in extreme conditions", CEXTREME LAB, functions within the Department of Materials Science and was accredited in September 2015 by the Committee for Accreditation of Scientific Research Institutions of the Republic of Serbia. Research groups within the Department are involved not only in fundamental research, but also for specific development and applied research.

The Department comprises the following laboratories: Laboratory for Processing and Synthesis of Materials for Application in Extreme Conditions, Laboratory for Qualitative and Quantitative Microstructural Analysis, Laboratory for Identification and Structural Characterization of Materials Using X-Ray Diffraction Analysis, Laboratory for the Physical and Chemical Surface Characterization of Materials for Application in Extreme Conditions, Laboratory for Theoretical Investigation of Materials (L-TIM), etc.

This Department has had long experience of dealing with nuclear materials. The nuclear program was performed decades ago. Now, researchers have both experimental and theoretical experience they have gained by working for international research projects, the results of which were published in the leading international journals (such as a bilateral project with the Department of nuclear chemistry, Comenius university in Slovakia with the subject matter of which is concerned with the removal of radioactive elements from water in addition to published contributions to the Journal of Nuclear Materials, Journal of Radioanalytical and Nuclear Chemistry, etc).