Etudes chimiques et isotopiques de l'uranium, du plomb et de plusieurs produits de fission dans un echantillon de minerai du reacteur naturel d'Oklo

Reappraisal of the limit on the variation inαimplied by the Oklo natural fission reactors

“…These results for Gd isotopes have a bearing on the resolution of the "second solution" problem [8]. From the comparison [71] of measured rare earth isotope abundances in Oklo sample KN50-3548 with calculations based on present-day neutron absorption cross sections, it can be inferred [21] that shifts ∆E i in resonances must be less than 50 meV in magnitude. Nevertheless, the results [23] of Damour and Dyson for Oklo samarium data alone can be interpreted [8] to mean that ∆E i lies in either a "right branch" ∆E i = 46 ± 22 meV, compatible with zero, or a "left branch" ∆E i = −94 ± 13 meV, inconsistent with the 50 meV bound on |∆E i |.…”

Natural nuclear reactor at Oklo and variation of fundamental constants: Computation of neutronics of a fresh core

“…A resonance shifts on the energy scale with changes of the nuclear potential similarly as the frequency of an ordinary radio receiver shifts when the parameters of the resonance circuit are changed (Fig.6) [55]. Qualitatively one can understand the absence of a significant shift of the near-threshold resonances on the grounds that all strong absorbers are highly burnt up in the Oklo reactor and weak absorbers are burnt up weakly (Fig.7) [10,56]. Holes in the distributions are seen for strong absorbers: Gd.…”

Reconstruction of cumulative fission yield curve and geochemical behaviors of fissiogenic nuclides in the Oklo natural reactors.

“…(Ruffenach et al, 1976), the pro portions of fission for 235U, 238U and 239Pu to total fission can be calculated. However, the results obtained here show a wide variation of the proportions in question and it is difficult to evaluate definitely their numerical values.…”