资源环境科技发展态势分析平台

Understanding the circumstances of the undeclared 2017 nuclear release of ruthenium that led to widespread detections of the radioisotope Ru-106 in the Eurasian region, and whether it derives from a civilian or military source, is of major importance for society and future improvements in nuclear safety. Until now, the released nuclear material has merely been studied by analyzing short-lived radioisotopes. Here, we report precise measurements of the stable isotopic composition of ruthenium captured in air filters before, during, and after the nuclear release, and find that the ruthenium collected during the period of the 2017 nuclear release has a non-natural isotopic composition. By comparing our results with ruthenium isotopic compositions of spent nuclear fuels, we show that the release is consistent with the isotopic fingerprints of a civilian Russian water-water energetic reactor (VVER) fuel at the end of its lifetime, and is not related to the production of plutonium for nuclear weapons. A cloud of enhanced ruthenium concentrations has been observed over Europe in 2017, but no country has acknowledged responsibility for this nuclear release. Here, the authors show that the stable isotopic composition of ruthenium emitted from nuclear fuel reprocessing during the 2017 event is consistent with the isotopic signature of civilian Russian nuclear reactor fuel.