Microscopic radioactive particles released during the 1986 Chernobyl nuclear power plant disaster are breaking down more slowly than experts had expected. That is the conclusion of German physicists and crystallographers from Leibniz University Hannover and the Helmholtz-Zentrum Dresden-Rossendorf, who studied samples of so-called hot particles, infohub.kz reports.
The study examined microscopic fragments of nuclear fuel measuring between 8 and 50 micrometers that were scattered into the environment during the catastrophe. The analysis showed that the crystal structure of the fuel in many of the fragments has survived far better than previously believed.
For the study, the scientists used X-ray diffraction at a synchrotron in Grenoble. They measured the structure of six isolated particles at 2,000 different angles. The results showed that the explosion and the fire that followed produced three types of fragments. Some retained the properties of uranium dioxide, others fused with a protective zirconium layer under extreme temperatures, and a third group oxidized over ten days of graphite burning. According to the researchers, the high chemical stability of the first two types is what prevents radioactive substances from being quickly washed out into soil and water.
The authors stress, however, that their conclusions are based on only six fragments from two locations. Because of inevitable differences in the structure of the particles, the Chernobyl exclusion zone will remain hazardous to humans for a long time to come. The scientists are continuing their research in order to better assess the behavior of heavier transuranic elements.