Scientists have found that crushed concrete from old nuclear facilities can actively trap strontium-90, a radioactive contaminant found at sites like Sellafield in the United Kingdom and Hanford in the United States. The research was published in ACS ES&T Water and conducted by scientists from the University of Manchester, the UK National Nuclear Laboratory, and Clemson University.
Strontium-90 is a persistent problem at legacy nuclear sites because it moves easily through soil and groundwater. Finding cost-effective ways to contain it onsite has been a long-standing challenge for nuclear decommissioning programs.
The research team used concrete sourced from the UK's Nuclear Decommissioning Authority. They mixed it with synthetic groundwater containing either stable strontium or trace amounts of radioactive strontium-90. Experiments ran for three months under two different conditions: one with limited air, representing sealed or underground environments, and one with normal air exposure.
In the air-exposed systems, crushed concrete removed around 82 percent of strontium from solution within three months. In the air-limited systems, that figure was only 14 percent. The difference came down to the formation of calcite, a calcium carbonate mineral that forms when concrete reacts with carbon dioxide in the air. Strontium can substitute for calcium in calcite, locking into its mineral structure. X-ray absorption spectroscopy confirmed that strontium was partially incorporated into newly formed calcite in the air-exposed systems.
The team also tested phosphate treatments. Concrete pretreated with phosphate or treated during the experiment showed increased strontium uptake even when air was limited. In air-exposed systems with phosphate added, up to 98 percent of strontium was removed from solution within 48 hours. Microscopy revealed that poorly crystalline calcium phosphate coatings formed on the concrete surface, creating additional sites where strontium could bind over long periods and eventually decay to stable zirconium.
Professor Katherine Morris, BNFL Research Chair at the University of Manchester and senior author of the study, described what the findings mean for managing radioactive waste. "Our work shows that crushed concrete doesn't just act as an inert waste material—it can actively remove strontium from solution and hold onto it in forms that are stable over long timescales. That's important for understanding how lightly contaminated concrete could be applied onsite to minimize radionuclide transport," she said.
The research opens a potential path for reusing demolished nuclear site materials rather than disposing of them, reducing the volume of waste that needs to be transported or stored at regulated facilities. Further work is expected to examine how the approach might scale to real site conditions.
