Four decades after the explosion at the Chernobyl Nuclear Power Plant, tiny radioactive fragments known as 'hot particles' still linger in the soil of the exclusion zone. These particles, measuring only 8 to 50 micrometers, were blown out of the reactor during the accident and remain highly radioactive. An international team from Leibniz University Hannover and the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) collected six such particles from Ukrainian soil samples and prepared them for structural analysis by attaching each to a tungsten electrode and isolating them with multiple confinement layers.
This image relates to the article's discussion of radioactive hot particles remaining in the Chernobyl Exclusion Zone.
Using synchrotron X‑ray diffraction at the Rossendorf Beamline in Grenoble, the scientists rotated each particle in a beam focused to about 100 micrometers and recorded reflections from 2,000 different angles to reconstruct the internal crystal structure. The primary source reports that this methodological approach enabled the first ever phase‑specific examination of individual Chernobyl hot particles. The analysis revealed that the uranium dioxide fuel core within the particles has remained largely intact despite four decades of environmental exposure. Instead of degrading into various uranium oxides as previously assumed, the fuel’s crystal lattice showed little distortion, meaning the particles are chemically more stable than earlier models predicted.
Consequently, the particles continue to retain fission products within their matrix rather than leaching them out rapidly. This retention could reduce the immediate migration of radionuclides into groundwater and soil, although the particles themselves remain hazardous due to their ongoing radioactivity. However, the study’s authors caution that the findings are based on only six particles collected from two distinct locations, and each particle exhibited a unique internal structure. Because of this variability and the limited sample size, the results cannot be extrapolated to make broad statements about the overall stability of Chernobyl hot particles or the long‑term health risks for humans and ecosystems in the exclusion zone. The researchers note that even if average decay rates were uniform, outlier particles that persist longer could still release radionuclides at unpredictable times, implying that restrictions on the Chernobyl Exclusion Zone are unlikely to be lifted soon. Ongoing work by the same team is now focusing on the transuranic phases of the debris to further understand the longevity of the most radioactive components.