8. Isotopes of plutonium and americium 241 in the French metropolitan environment

8.1 Origins and ratios of isotopic activity

Nuclear weapon explosions have induced the release of plutonium-239 and plutonium-240, for which the ratio of isotopic activities ²⁴⁰ Pu/ ²³⁹ Pu was 0.18. The ratio of these isotopic activities has hardly changed since then, due to the long radioactive half-life of these radionuclides. The ratio of these isotopic activities has hardly changed since then, due to the long half-lives of these radionuclides. As the energies of the alpha particles emitted by plutonium-239 and plutonium-240 are very close, these two radionuclides cannot be discriminated by the most widely used measurement technique, alpha spectrometry. The activity of plutonium 239+240 (...