Record of Cycling Operation of the Natural Nuclear Reactor in the Oklo/Okelobondo Area in Gabon

Meshik, A. P.; Hohenberg, C. M.; Pravdivtseva, O. V.

doi:10.1103/physrevlett.93.182302

Cited by 57 publications

(36 citation statements)

References 15 publications

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“…[44,45] The reactor could have worked also in a pulsating mode: when the temperature exceeded 710 K, then the unbound water was boiled away and the reactor stopped on account of the void effect. Then the water returned and it started to work again [34,46,47,48]. However a detailed analysis of the pulsating mode of operation of the reactor is outside the scope of the present paper.…”

Section: Power Effectmentioning

confidence: 97%

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

et al. 2006

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Using modern methods of reactor physics we have performed full-scale calculations of the natural reactor Oklo. For reliability we have used recent version of two Monte Carlo codes: Russian code MCU REA and world wide known code MCNP (USA). Both codes produce similar results. We have constructed a computer model of the reactor Oklo zone RZ2 which takes into account all details of design and composition. The calculations were performed for three fresh cores with different uranium contents. Multiplication factors, reactivities and neutron fluxes were calculated. We have estimated also the temperature and void effects for the fresh core. As would be expected, we have found for the fresh core a significant difference between reactor and Maxwell spectra, which was used before for averaging cross sections in the Oklo reactor. The averaged cross section of 149 62 Sm and its dependence on the shift of resonance position (due to variation of fundamental constants) are significantly different from previous results.Contrary to results of some previous papers we find no evidence for the change of the fine structure constant in the past and obtain new, most accurate limits on its variation with time: −4 · 10 −17 year −1 ≤α/α ≤ 3 · 10 −17 year −1 . A further improvement in the accuracy of the limits can be achieved by taking account of the core burnup. These calculations are in progress.

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Section: Power Effectmentioning

confidence: 97%

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

et al. 2006

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“…According to Equation 2 the relation between the electric charges q(r) and q is determined by the parameters k 1 and B. Between the parameters k and A the following relation holds: The value of parameter W is calculated (De Laeter et al, 1980;King et al, 2011;Manousos, 2013c;Meshik et al, 2004;Petrov et al, 2006;Webb et al, 1999;2001; to be Equation 6: 4 km W 1.2 10 sMpc…”

Section: Introductionmentioning

confidence: 99%

The Numerical Values of the Fundamental Parameters of the Model of Selfvariations and the Age of the Universe

Manousos¹

2014

Physics International

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The law of selfvariations determines quantitatively a slight increase of the rest masses and the electric charges of material particles as a common cause of quantum and cosmological phenomena. At cosmological scales the law of selfvariations can be expressed by two similar differential equations for the rest mass and the electric charge respectively. These equations contain information and justify the totality of the cosmological data. Solving these equations, we introduce two parameters k, A for the rest mass and another two k 1 , B, for the electric charge. Knowledge of the numerical values of these four parameters suffices for the accurate determination of the predictions of the law of selfvariations at cosmological scales. In the present article we determine the intervals in which these fundamental parameters obtain their values. As an aside, the conclusion emerges that the age of the Universe is far larger than the one predicted by the Standard Cosmological Model. A very long time of evolution is predicted until the Universe takes the form in which we observe it today.

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“…The rate of fission can be deduced from the Hidaka and Holliger model [20], which found an average RZ10 neutron fluence of 0.65 kb −1 over a time duration of 160 kyr. From analysis of xenon isotope abundances in Oklo grains of aluminum phosphate, Meshik et al [21] concluded the reactors operated cyclically, with reactor-on periods of about 0.5 hr (1800 s), separated by dormant reactor-off periods of 2.5 hr (9000 s). We use this periodicity in calculating absolute fluxes.…”

Section: Introductionmentioning

confidence: 99%

γ-ray fluxes in Oklo natural reactors

2012

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Background: Uncertainty in the operating temperatures of Oklo reactor zones impacts the precision of bounds derived for time variation of the fine structure constant α. have been undertaken by many groups investigating whether the fine structure constant α has changed over the 2 GY period since the reactors operated. As first pointed out by Shlyachter [2], the samarium isotopic ratios are sensitive to the value of α through the overlap of the 149 Sm E 0 =97.3-meV neutron resonance with the thermal and epithermal portions of the neutron flux in the reactor. While the majority of Oklo analyses [3][4][5][6][7], have been consistent with no shift in the resonance energy, and therefore no change in α, a change has been argued for from astronomical observations [8].All Oklo analyses make assumptions about the operating temperatures of the reactors. But there is as yet no agreement on what these temperatures actually were. Utilizing the 176 Lu/ 175 Lu isotope ratio method to determine temperatures was recently revisited by Gould and Sharapov [9] . The method is based on the temperature dependence of the large thermal neutron capture cross section of 176 Lu (natural abundance 2.599 % [10]), and on knowing with certainty the (small) ground state branching ratio for thermal neutron neutron capture on the more abundant lutetium isotope, 175 Lu (natural abundance 97.401 %). The dominant capture branch σ

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Record of Cycling Operation of the Natural Nuclear Reactor in the Oklo/Okelobondo Area in Gabon

Cited by 57 publications

References 15 publications

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

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

The Numerical Values of the Fundamental Parameters of the Model of Selfvariations and the Age of the Universe

γ-ray fluxes in Oklo natural reactors

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