Electrokinetic remediation of plutonium-contaminated nuclear site wastes: Results from a pilot-scale on-site trial

This paper examines the field-scale application of a novel low-energy electrokinetic technique for the remediation of plutonium-contaminated nuclear site soils, using soil wastes from the Atomic Weapons Establishment (AWE) Aldermaston site, Berkshire, UK as a test medium. Soils and sediments with varying composition, contaminated with Pu through historical site operations, were electrokinetically treated at laboratory-scale with and without various soil pre-conditioning agents. Results from these bench-scale trials were used to inform a larger on-site remediation trial, using an adapted containment pack with battery power supply. 2.4m3 (ca. 4tonnes) of Pu-contaminated soil was treated for 60 days at a power consumption of 33kWh/m3, and then destructively sampled. Radiochemical data indicate mobilisation of Pu in the treated soil, and migration (probably as a negatively charged Pu–citrate complex) towards the anodic compartment of the treatment cell. Soil in the cathodic zone of the treatment unit was remediated to a level below free-release disposal thresholds (1.7Bq/g, or