Traces of xenon gas have been detected in South Korea following North Korea’s sixth nuclear test last Sunday.
 
The Nuclear Safety and Security Commission said the radioactive material, xenon-133 isotope, was discovered five days after the nuclear test in samples collected from the ground, air and sea in South Korea.
 
The detected amount measures zero-point-43 millibecquerel per cubic meter. The commission is trying to track the inflow of xenon to determine if it’s a result of the nuclear test.
 
Radioactive xenon not naturally occurring is typically considered proof of a nuclear explosion. If various artificial isotopes of xenon are detected at the same time, this can also provide information on how the nuclear test was carried out.