Crushed Nuclear Plant Concrete Can Capture 98% of Radioactive Waste Within 48 Hours

Crushed Nuclear Plant Concrete Can Capture 98% of Radioactive Waste Within 48 Hours

UK researchers have discovered that waste concrete from decommissioned nuclear power plants, once crushed, can capture radioactive strontium-90 for decades — offering a more effective method for managing nuclear-contaminated waste materials.

The study was conducted jointly by teams from the University of Manchester, the UK National Nuclear Laboratory (UKNNL), and Clemson University in the United States. The researchers found that crushed concrete actively captures and retains strontium-90.

Strontium-90 is a radioactive isotope produced by nuclear fission and is one of the most mobile radioactive contaminants found at nuclear facilities such as Sellafield in the UK and Hanford in the United States. With a half-life of approximately 28.8 years, it decays into yttrium-90 and releases high-energy beta particles.

The findings could improve long-term management of lightly contaminated concrete generated during nuclear plant decommissioning. "These results give us a clearer understanding of how concrete waste interacts with groundwater over long timescales," said Dr. Katherine Morris, BNFL Research Chair and senior author of the study.

An Unexpected Solution for Waste Treatment

Strontium-90 poses a significant environmental threat due to its ability to migrate through groundwater, and it is widely present in nuclear reactor waste. Large quantities of strontium-90 were released during both the 1986 Chernobyl nuclear disaster and the 2011 Fukushima Daiichi accident.

As ageing nuclear facilities continue to be decommissioned, the volume of lightly contaminated concrete waste generated on-site is growing. To understand the long-term behaviour of these materials, the research team tested crushed concrete provided by the UK's Nuclear Decommissioning Authority.

Researchers mixed the crushed concrete with synthetic groundwater containing either stable strontium or trace amounts of strontium-90, then conducted experiments over three months under two disposal scenarios: one simulating a sealed, low-oxygen environment (limited air contact), and another simulating air-exposed conditions similar to shallow near-surface disposal.

"Our research shows that crushed concrete is not simply an inert waste material — it actively removes strontium from solution and retains it in a long-term stable form," Morris explained.

Under air-equilibrated conditions, crushed concrete removed approximately 82% of strontium from solution over three months; under low-oxygen conditions, only around 14% was removed over the same period. Air exposure promotes a reaction between the concrete and carbon dioxide, producing the mineral calcite. Since strontium can substitute for calcium in the calcite crystal structure, the mineral effectively immobilises the radioactive element in a stable form.

A New Strategy for Nuclear Decontamination

The research team used X-ray absorption spectroscopy to confirm that strontium had been incorporated into newly formed calcite, providing a concrete mechanism for the long-term removal of strontium-90 from groundwater.

The researchers also tested whether phosphate treatment could further enhance performance, using two approaches: adding phosphate during the experiment, and pre-treating the concrete beforehand. Both methods increased strontium uptake, even under low-oxygen conditions.

In phosphate-treated, air-exposed systems, strontium removal reached 98% within 48 hours.

Phosphate also forms a low-crystallinity calcium phosphate coating on the concrete surface, providing additional strontium binding sites and preventing strontium from migrating as it progressively decays into stable zirconium.

The team's findings suggest that crushing concrete and exposing it to air during recycling or shallow burial can significantly enhance its ability to immobilise radioactive contaminants; in low-oxygen environments, phosphate treatment can be used to strengthen this effect.

"By understanding the mechanisms by which strontium is captured, we can more robustly support science-based decisions on near-surface disposal and the long-term management of radioactively contaminated land," Morris concluded in a statement.

The study has been published in the academic journal ACS ES&T Water.

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