Advanced In-situ Instrumentation for HLW Tank Mixing and Retrieval

As the DOE’s Hanford site begins preparations for the transfer of high-level radioactive waste (HLW) from the double-shell tank s (DST) to
the Waste Treatment and Immobilization Plant (WTP), the influence of waste feed consistency on the waste stabilization process – and
final stabilized waste form - is currently under analysis. In order to characterize feed consistency prior to transfer, a suite of instrumentation
will be required to monitor the waste preparation and mixing process in real time. FIU has focused its instrumentation efforts on identifying
improvements to the in-situ, near-real time monitoring of the mixing process. Specifically, this project has identified innovative technologies
applicable for in-tank monitoring of slurry rheological characteristics. Prior technology evaluation methods have identified in-situ ultrasonic
techniques as viable approaches for monitoring of the mixed suspension characteristics, but the potential benefits of broadband analysis
and spectroscopic techniques have not been considered. This project evaluated the use of an ultrasonic spectroscopy (USS) method in the
characterization of high-level radioactive waste mixing within a +1M gallon tank. The method can provide material characteristics across a
wide bandwidth, the bulk density of the mixed suspension, and has the potential to track changes during the mixing process. The
evaluation consisted of testing a commercially-available variant in a matrix of suspensions; the technology was lowered into a mixing
vessel for real-time sampling a various tank heights. The density results were compared to standard in-line commercial technologies
utilized in the nuclear and process industry.