Nuclear Sorbents

Inherited from Biomedy AG, Aliteco manages the production of a quite large range of metallic sorbents for radio-nuclides (RAXORB). The metallic nature of RAXORB allows a stable and long term sorption-and-storage solution for the decontamination of heavy radioactive wastes. Since a high retention factor, preventing any washout even in the most aggressive environment, and because the very high sorption capacity, radioactive RAXORB can be easily and directly disposed in the repository; washout, condensation, solidification are not required.

RAXORB is a ion-exchanger like inorganic sorbent, especially developed for the deactivation of technological fluids in the nuclear power industry as fluids in the primary cooling circuit, fluids of cooling ponds of spent nuclear fuel, condensate of evaporators, regenerators of ion-exchange resins, liquid radioactive wastes. A customized version is particularly suitable for ⁹⁹Tc sorption/separation from ⁹⁹Mo. Besides, in consideration of its relatively low price and its high sorption characteristics, RAXORB has found commercial applications for potable water purification and wine filtration.

RAXORB is made of hydrated oxides of titanium, tin and zirconium combined with phosphates in rutile or anatase crystalline structures developing a specific surface of 70-150 m²/g. The sol-gel technique used to produce RAXORB generates mechanically strong spherical granules with high kinetic characteristics.

RAXORB is stable to radiations making it suitable for the construction of ion-exchanger filtering devices for the deactivation of strongly radioactive solutions. Ultimately, RAXORB represents the best alternative to the use of organic ion-exchange resins which application is often limited because of their poor stability under the effect of ionizing radiations. Ion-exchangers based on the highly selective RAXORB ensure an operational life up to 100 times longer than the life of organic ion-exchange resins in similar conditions. The long operational life allows a high capture rate of radionuclides from solutions including mineralized (saline) ones.

RAXORB effectively works in presence of radionuclides concentration in aqueous and water-organic solutions exceeding 0.1 g/dm³. It is characterized by extremely low water solubility that means high intrinsic safety: at a temperature of 300°C and a pressure of 15 MPa, the solubility is less than 1x10⁻⁶ g/dm³. RAXORB is thermally stable so preserving its physicochemical and sorption properties in presence of pressurized water up to 350°C.

RAXORB is chemically stable in respect to oxidizing agents, reducing agents, acids and alkalis. Stability to radiations together with thermal and chemical stability allow the application of RAXORB in high-pressure and high-temperature environments like deactivation of the primary cooling circuits in nuclear reactors.

As any other ion exchange sorbent, to maximize sorption capacity towards specific elements, RAXORB would better perform if customized on the characteristics of the media and on the nature of the ions. ALITECO provides four major families of inorganic sorbents:

• RAXORB³ based on zirconium hydroxide, selective towards polyvalent anions.
• RAXORB^3A based on zirconium phosphate, selective towards most of the cations.
• RAXORB⁵ based on titanium and zirconium oxides, associated with catalytic activity.
• RAXORB³⁵ based on ferrocyanide and zirconium oxide, specific for Cesium.

Currently RAXORB is in use in several nuclear power plants in Russia as well in some European facilities, mostly in Switzerland and UK. Minding that Aliteco is entitled to disclose nicknames only under confidentiality agreement, at the sole explanatory purposes, the following are some application cases showing RAXORB dynamics of sorption:

• App Rx401 - Deactivation of spent fuel cooling ponds water of the first stage of B401 nuclear power plant.
• App Rx503 - Decontamination from radionuclides of condensates of evaporators at K503 nuclear power plant.
• App Rx504 - Decontamination from radionuclides of condensates of evaporators at B504 nuclear power plant.
• App Rx553 - Deactivation of demineralization reclaims block of K503 nuclear power plant.
• App Rx618 - Deactivation of distillation residues at U618 nuclear power plant from radionuclides of Cesium.
• App Rx701 - Deactivation of high-temperature heat transfer liquid at B401 nuclear power plant.