A new sol-gel derived optical fiber sensor for high acidity measurements: Application in nuclear fuel reprocessing

Nuclear fuel reprocessing requires high acidity levels that should be accur ately and rapidly controlled in order to optimize extraction yields and pro cess efficiency. A new optical fiber sensor based on a sol-gel film doped w ith an acid-sensitive indicator has been developed to improve remote and on -line monitoring. The organic molecule was physically incorporated in an acid-catalyzed sol-g el matrix and coated onto the core of a denuded optical fiber. The sensor r esponse was evaluated in synthetic solutions of nitric acid, concentrations ranging from 1 to 10 mol.l(-1). Changes in absorption properties and respo nse characteristics of the sensor, when compared to the indicator in soluti on, have been discussed. Analytical performances of the sensor, i.e. sensit ivity, response time, reversibility and repeatability are very encouraging for the on-line analysis. Viability of the sensor for process measurements depends on the stability which might be improved by a strict control of the sensitive film porosity.