Characterisation of individual micron sized nuclear weapons fragments from the Thule area by rL-SNMS

Abstract In 1968, a US military aircraft equipped with nuclear weapons crashed in Thule, Greenland. As a result, plutonium containing fragments were scattered into the environment. In this work, four hot particles from the Thule area were identified and separated. The 241 Am activity of the particles was determined with gamma spectrometry. Resonant-laser secondary-neutral mass spectrometry was used to determine the isotope ratios of uranium and plutonium. Isotope ratios of 240 Pu/ 239 Pu > 0.055 and 235 U/ 238 U > 1.2 were observed. A hypothesis is proposed to explain the unexpectedly low uranium enrichment for the nuclear weapons.