Design of an intensified coprecipitation reactor for the treatment of liquid radioactive wastes

In the nuclear industry, important volumes of liquid wastes have to be treated to reduce their contents in radioactive contaminants. The coprecipitation is the method mostly applied to perform decontamination of liquid wastes which cannot be concentrated by evaporation. Two operating modes are typically used for an industrial scale treatment by coprecipitation: the continuous and the semi-batch process. It was proved experimentally and theoretically that the semi-batch reactor ensures decontamination efficiency much higher than the continuous stirred tank reactor. An innovative reactor with an infinite recycling ratio is therefore designed to optimize the continuous treatment: the reactor/classifier reaches the same efficiency decontamination as the semi-batch process and represents an efficient device for the coprecipitation process intensification. Hereafter is presented this new coprecipitation reactor and its experimental application to a concrete case of nuclear decontamination. Modelling of this process is totally new: it validates experimental results and also presents theoretical equations to predict decontamination efficiency. (authors)