Gibt es Plutonium auf der Welt, abgesehen von der Herstellung?
Ja.
Abgesehen vom Naturreaktor in Gabun, siehe Walter Boshalter geht man davon aus, dass auch SPUREN des langlebigsten Plutonium-Isotops Pu 244 existieren - aber nur etwa NEUN GRAMM in der GESAMTEN ERDRINDE.
Plutonium-244 - Wikipedia
Isotope of plutonium Plutonium-244 ( 244 Pu) is an isotope of plutonium that has a half-life of 80 million years. This is longer than any of the other isotopes of plutonium and longer than any other actinide isotope except for the three naturally abundant ones: uranium-235 (704 million years), uranium-238 (4.468 billion years), and thorium-232 (14.05 billion years). Although studies are in conflict, given the mathematics of the decay of plutonium-244, an exceedingly small amount should still be present in the Earth's composition, making plutonium a likely although unproven candidate as the shortest lived primordial element . Natural occurrence [ edit ] Accurate measurements, beginning in the early 1970s, have detected primordial plutonium-244, [3] making it the shortest-lived primordial nuclide. The amount of 244 Pu in the pre- Solar nebula (4.57×10 9 years ago) was estimated as 0.8% the amount of 238 U. [4] .As the age of the Earth is about 57 half-lives of 244 Pu, the amount of plutonium-244 left should be very small; Hoffman et al. estimated its content in the rare-earth mineral bastnasite as c 244 = 1.0×10 −18 g/g, which corresponded to the content in the Earth crust as low as 3×10 −25 g/g [3] (i.e. the total mass of plutonium-244 in Earth's crust is about 9 g). Since plutonium-244 cannot be easily produced by natural neutron capture in the low neutron activity environment of uranium ores (see below), its presence cannot plausibly be explained by any other means than creation by r-process nucleosynthesis in supernovae or neutron star mergers . Plutonium-244 is thus the shortest-lived and the heaviest primordial isotope yet detected or theoretically predicted. Trace amounts of 244 Pu (that arrived on Earth within the last 10 million years) were found in rock from the Pacific ocean by a Japanese oil exploration company. [5] The detection of primordial 244 Pu in 1971 is not confirmed by recent, more sensitive measurements [4] using the method of accelerator mass spectrometry . In this study, no traces of plutonium-244 in the samples of bastnasite (taken from the same mine as in the early study) were observed, so only an upper limit on the 244 Pu content was obtained: c 244 < 0.15×10 −18 g/g, which is 370 (or less) atoms per gram of the sample, at least 7 times lower than the abundance measured by Hoffman et al. Live interstellar plutonium-244 has been detected in meteorite dust in marine sediments, although the levels detected are much lower than would be expected from current modelling of the in-fall from the interstellar medium . [6] It is important to recall, however, that in order to be a primordial nuclide – one constituting the amalgam orbiting the Sun that ultimately coalesced into the Earth – that plutonium-244 must have comprised some of the solar nebula, rather than having been replenished by extrasolar meteoritic dust. The presence of plutonium-244 in meteoritic composition without evidence the meteor originated from the formational
https://en.wikipedia.org/wiki/Plutonium-244
Theoretisch könnte Pu 244 durch EXTRASOLARE Asteroiden frisch auf die Erde gelangen.
Asteroiden, die also aus einer Himmelsregion stammen, wo über Supernovae oder "Neutronenstern-Verschmelzung" Pu 244 vor nach astronomisch-geologischer junger Zeit neu entstand.
Dafür gibt es aber offenbar keinen Beweis, weil extrasolare Asteroiden per se selten sind, und nur eine Minderheit aus solchen Regionen stammen dürfte.