Isotopes may indicate 2010 North Korean nuclear test

Nature : Radioisotopes collected from atmospheric samples suggest that North Korea may have tested two nuclear weapons in 2010, if a new analysis by Lars-Erik De Geer of the Swedish Defence Research Agency in Stockholm is correct. De Geer examined radioisotope data from Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) monitoring stations, then he compared them with South Korean monitoring data and meteorological records. After about a year of work, he concluded that North Korea carried out two small nuclear tests in April and May 2010. According to De Geer, the detection of xenon-133 and xenon-133m points toward an explosion in the middle of April, and the presence of barium-140 and its radioactive decay product lanthanum-140 indicates that there was a second test in early or mid May. However, the seismic data from that time don’t corroborate the radioisotope data, and the Korean peninsula is well equipped to detect the vibrations that would come from a nuclear explosion. Another possible explanation for the presence of the isotopes is that a reactor accident took place. De Geer hopes that his paper, due to appear in the April/May issue of the journal Science and Global Security, will prompt other scientists in CTBTO member states to reexamine the data.