An Integrated In Situ Raman and Turbidity Sensor for High Level Waste Tanks

Stored nuclear waste must be retrieved from storage, treated, separated into low- and high-level waste streams, and finally put into a disposal form that effectively encapsulates the waste and isolates it from the environment for a long period of time. Before waste retrieval can be done, however, waste composition will need to be characterized so that proper safety precautions can be implemented during the retrieval process. In addition, there is a need for active monitoring of the dynamic chemistry of the waste during storage since the composition of the waste can become highly corrosive. A novel fiber optic Raman transmission and light scattering probe will be developed with improved sensitivity and capability to operate in turbid media. The dual Raman and turbidity sensor will provide chemical identification of nuclear waste as well as information concerning the suspended particles in the waste (turbidity, particle size distribution). In Phase I, we successfully demonstrated a new fiber optically coupled probe design and associated instrumentation that allows simultaneous measurement of the Raman spectrum and turbidity using the same laser source. The measurement system returns accurate concentrations of a range of Raman active anions present in HLW under conditions of varying turbidity and also corrects for fluctuations in laser intensity. Based on the prototype Raman/turbidity probe design that was developed in Phase I, a compact, fiber optically coupled, integrated Raman probe and turbidity sensor (RamanTurboProbe