Decommissioning Britain's old nuclear sites will generate mountains of lightly contaminated concrete, and a study suggests that waste could itself become a clean-up tool. Researchers from the University of Manchester, the UK National Nuclear Laboratory and Clemson University showed that crushed concrete from decommissioned nuclear facilities can trap radioactive strontium-90 from groundwater, one of the more troublesome fission products at legacy sites.
In experiments running three months, crushed concrete supplied via the UK Nuclear Decommissioning Authority was mixed with synthetic groundwater containing stable strontium or trace strontium-90, under both air-limited and air-exposed conditions, with X-ray absorption spectroscopy and microscopy used to track where the strontium went. Air exposure proved decisive: carbonation formed calcite into which strontium substituted for calcium, removing about 82 per cent of the strontium within three months, against just 14 per cent in air-limited systems.
Phosphate treatments pushed performance further still. With air access, up to 98 per cent of strontium was removed within 48 hours as poorly crystalline calcium phosphate coatings created retention sites on the concrete surfaces. Published in ACS ES&T Water, the findings could support decisions about disposing of lightly contaminated concrete on site, turning a costly waste stream into a passive barrier against radionuclide migration.