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Journal Articles Nuclear Engineering and Design Year : 2014

A topping gel for the treatment of nuclear contaminated small items


Nuclear decontamination is a key aspect of the decommissioning of facilities, can today be carried out using gelled reagents sprayed over contaminated surfaces (tens of square meters) and allows easy radionuclide retrieval. Wide ranges of formulations have been developed in our laboratory to treat several materials. The gels are formulated by adding colloidal silica particles to a reactive solution; they dry and form solid residues that are easily collected and directly conditioned. Dissemination hazards are reduced and no liquid effluent is generated or released. In order to adapt the process to the decontamination of small items, an original method involving a topping gel has been developed. A polysaccharide, carrageenan, is added to a conventional gel (silica particles + reactive solution) and by varying the temperature an abrupt sol-gel transition (around 45-50 degrees C) is observed. At high temperature, the low viscosity of the gel allows it to coat small parts easily, and simply removing them from the warm bath congeals the topping gel. Its decontaminating action takes place. The gel then dries and can be collected. A tradeoff has been found between the mineral mass fraction and the amount of carrageenan, and a formulation is proposed. Results on Co-60 contaminated black steel plates show that the decontamination factor is fully comparable to a conventional gel. Finally, drying kinetic measurements show that easily recoverable flakes are formed due to water evaporation.
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hal-01274187 , version 1 (15-02-2016)



Romain Castellani, Arnaud Poulesquen, Frédéric Goettmann, Philippe Marchal, Lionel Choplin. A topping gel for the treatment of nuclear contaminated small items. Nuclear Engineering and Design, 2014, 278, pp.481-490. ⟨10.1016/j.nucengdes.2014.07.043⟩. ⟨hal-01274187⟩
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