Utilisation of underwater acoustic backscatter systems to characterise nuclear waste suspensions remotely

This paper reports application of ABS (Acoustic Backscatter Systems) to address nuclear waste management within the UK. ABS offers a route towards an online monitoring system to characterise wastes safely and remotely in real-time, during pipeline transportation; resulting in reduced hazard reduction timescales and taxpayer cost savings. Here, an ultrasonic velocimetry profiler (UVP) was used to analyse glass dispersions of varying concentrations, to assess online waste monitoring applicability. Acoustic backscatter profiles were collected to establish attenuation coefficients for two glass sizes (∼40 and 80 µm) with 2 and 4 MHz probes. The 4 MHz probes were the most highly attenuating while transducer active radius had a negligible effect on probe sensitivity with either glass. A calibration procedure was used to measure sediment attenuation coefficients, which were compared to model estimates and experimental literature. For most systems, measured coefficients were close to estimated values, highlighting improved calibration accuracy, due to the mixing tank used. However, values for the smaller glass and 2 MHz probes overestimated model predictions, due to additional viscous attenuation. The measured value for the larger glass with 4 MHz probes was underestimated, this was caused by high attenuation reaching the instrument noise-floor, limiting the region available for analysis.