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

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 241Am 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 ²⁴⁰Pu/²³⁹Pu > 0.055 and ²³⁵U/²³⁸U > 1.2 were observed. A hypothesis is proposed to explain the unexpectedly low uranium enrichment for the nuclear weapons.