Simultaneous velocity and concentration profiling of nuclear waste suspensions in pipe-flow, using ultrasonic Doppler and backscatter analysis

Complex magnox ponds at Sellafield retain hydroxide-based sludge with unknown physicochemical properties where the sludge is a corroded form of magnesium-based fuel cladding. Long term storage and open-air aqueous conditions have been major contributors to corrosion and now the waste requires transportation to interim storage using engineered pipelines. Remote in situ characterization of sludge was achieved using a non-invasive ultrasonic velocity profiler (UVP) which monitored suspensions in a bespoke pipe-loop designed to mimic flows encountered in the nuclear industry. Spherical glass particles with two size distributions of known acoustic behavior were analyzed to extract raw velocity and echo amplitude for velocity and acoustic profiling which provided insight into the effect of particle size and concentration on attenuation. Four 4 MHz frequency transducers were mounted in-line on engineered pipelines, 90° and 135° to flow on horizontal and vertical pipe sections where acoustic profiles were compared to select the most efficient pipe arrangement. When comparing, the horizontal pipe section was found to enhance attenuation producing higher coefficient values, likely caused by suspension segregation. Simultaneous velocity profile measurement was achieved where profiles were as expected for highly turbulent flow. Moving forward, complex non-defined nuclear simulants will be analyzed to investigate the UVP’s limitations.