Forty years after the Chernobyl disaster, scientists discovered that some radioactive particles released during the 1986 explosion have retained much of their original structure, challenging assumptions about their long-term environmental impact.
Researchers from Leibniz University Hannover and the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) examined six microscopic radioactive particles collected from the Chernobyl Exclusion Zone. They found that some retained properties similar to the original nuclear fuel, uranium dioxide. The results, published in the Journal of Hazardous Materials, suggest that certain particles may hold radioactive substances within their structure for extended periods, potentially limiting environmental spread.
Three Classes of Particles, Diverse Stability
The study identified three distinct types of particles based on how they formed during the disaster. The first type remained chemically and physically similar to uranium dioxide, the primary component of nuclear fuel. The second type was partially or fully fused with a zirconium layer, which acted as a protective cladding during the reactor’s operation. The third type emerged when the reactor’s graphite moderator caught fire, oxidizing the fuel into fragile uranium oxides like U3O8. The third type of particle was created when the graphite-moderator caught fire,
explained Tobias Weissenborn, a physicist at Leibniz University Hannover. In the process, the fuel oxidized into various uranium oxides.
Dr. Christoph Hennig, a crystallographer at HZDR, led the structural analysis of these particles. Using synchrotron X-ray diffraction, his team rotated the particles in a focused X-ray beam, capturing reflections from 2,000 angles. Ultimately, we fully rotated the particles in an X-ray beam focused down to 100 micrometers,
Hennig said. We measured each particle from 2,000 different angles to seamlessly capture all the reflections.
This method revealed that the crystalline structure of the nuclear fuel in the particles had largely remained intact. The samples, secured within several layers of protective shielding, were sent to Grenoble, where the analysis was conducted at the Rossendorf Beamline.
Implications for Environmental Risk
The findings could improve models for predicting how radioactive contamination spreads through soil and water. If particles retain their structure, they may release radioactive substances more slowly, reducing immediate environmental risks. However, the researchers caution against broad conclusions. However, every single particle has a different structure,
Weissenborn warned, noting that the study only examined six particles from two locations. And even if we obtained some averages at some point, we still wouldn’t be able to make universal statements about health risks in the region.
Unanswered Questions, Future Research
Despite the breakthrough, uncertainties remain. Why some particles degrade faster than others is unclear, and the long-term effects of their instability are not fully understood. It remains unclear why these particles weather and break down at different rates in the environment,
Ynetnews reported. The team plans to investigate more samples, including transuranic phases, to better predict how Chernobyl’s radioactive legacy will evolve. Restrictions on the exclusion zone are expected to persist, as the study highlights both the resilience and the unpredictability of the disaster’s fallout.
During the disaster, the graphite moderator ignited and burned for 10 days, altering the fuel’s chemical composition. In the process, the fuel oxidized into various uranium oxides
—such as triuranium octoxide, or U3O8—according to Ynetnews. The research outcomes may enable scientists to refine predictions on the dispersion of radioactive contamination through soil and other materials near the Chernobyl site. Grasping the evolution of these particles over time is crucial for evaluating the potential migration of radioactive materials into the environment. The research highlights the complex interplay between time, chemistry, and environmental exposure. While some particles show surprising stability, others pose ongoing risks, reinforcing the need for continued monitoring. As Weissenborn stated, Even if the particles decay in a largely uniform pattern, there will always be outliers, more persistent particles, that will release radionuclides at a later point in time.