A voltammetric system for in-line heavy metal measurements in nuclear fuel reprocessing plants - development and operational experience

A voltammetric in-line measurement system for uranium and plutonium in aqueous steams has been developed. It comprises a desk-top computer, potentiostat and remote sensor. A sensor consists of noble metal electrodes (working, counter, quasi-reference) assembled in a single probe, which can be operated over large distances. The potentiostat is capable of performing modern pulse voltammetry techniques, and has a floating (not earthed) working electrode facility which allows measurement of earthed (stainless steel plant) streams. The operating software is completely accessible to the user. The flexibility of the software allows continuous conditioning of the sensing electrode, and hence good measurement reproducibility over long periods. Aspects of underlying studies into the effects of common plant variables (physical and chemical) on remote voltammetric measurements are discussed. The measurement system and installations in development rigs and in the Fast Reactor Fuel Reprocessing Plant, Dounreay Nuclear Power Development Establishment, are described. Operational experience of these installed measurement systems is discussed. (author)