Radionuclide Evidence for Low-Yield Nuclear Testing in North Korea in April/May 2010

Between 13 and 23 May 2010, four atmospheric radionuclide surveillance stations, in South Korea, Japan, and the Russian Federation, detected xenon and xenon daughter radionuclides in concentrations up to 10 and 0.1 mBq/m3 respectively. All these measurements were made in air masses that had passed over North Korea a few days earlier. This article shows that these radionuclide observations are consistent with a North Korean low-yield nuclear test on 11 May 2010, even though no seismic signals from such a test have been detected. Appendix 1 presents a detailed analysis of the radioxenon data and Appendix 2 describes a hypothetical nuclear test scenario consistent with this analysis, including the possibility that the test used uranium-235 rather than plutonium-239. The analysis suggests that the technical and analytical basis to detect small nuclear tests using radionuclide signatures may be more developed than is generally assumed.