Assessing nanoparticle populations in historic nuclear waste

Lead Research Organisation: University of Liverpool
Department Name: Engineering (Level 1)

Abstract

Legacy ponds at the Sellafield site have been used to store historic radioactive waste for decades and progress is being made in reducing the risks associated with these facilities . Over time, there has been a deterioration in the condition of the ponds and their contents that has resulted in particles being present in solution in the ponds. It is important to characterise these particles, whose size are believed to range in diameter from nanometres to microns, in order to facilitate further reductions in the risks. Commercially-available instrumentation is capable assessing the size and number of particles in a solution, based on their motion, when the particles have diameters large than about 150nm; however, recent research has shown that particles with smaller diameters exhibit different behaviour leading to erroneous measurement results in these instruments. At low concentrations, the motion of nanoparticles with diameters less than about 150nm has been found to be independent of their size, density and material. These findings were obtained by tracking particles using the three-dimensional optical signature, or caustic, which they generate in an optical microscope, that can be several orders of magnitude larger than the particle . In this project, it is proposed to extend this work by developing an instrument that is capable of assessing the number and size of small nanoparticles in a solution that is representative of those recovered from the legacy ponds at Sellafield. The research will be undertaken using existing facilities at the University of Liverpool, initially using simple solutions and then progressing to non-radioactive simulants of the pond solutions. The long-term goal is to transition the technology to the Sellafield site and, hence, the final stage of the PhD project will be to demonstrate the technology on pond solutions using the facilities of the National Nuclear Laboratory.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/S022295/1 01/04/2019 30/09/2027
2270917 Studentship EP/S022295/1 23/09/2019 30/09/2023 Kristina Kara