Some comments on the presence of Chernobyl derived 137Cs and 99Tc in the stratosphere

This paper discusses previous results obtained by the authors on the content of 137Cs and 99Tc in rainwater samples collected at Sevilla (South-west Spain) from 1984 to 1988. It is confirmed that some part of the radioactive releases from the Chernobyl accident reached the stratosphere. In fact, it is estimated that, in 1987, some 83% of the 137Cs total fallout in our area originated from the Chernobyl accident, while some 17% came from previous nuclear atmospheric tests. Calculations have shown the possibility that some 99Tc were released to the environment during such an accident and reached the stratosphere to some extent.