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Mesure de la section efficace de fission induite par neutrons rapides des noyaux 232Th / 233U dans le cadre des cycles de combustiblesinnovants

Abstract : The thorium- 233U fuel cycle might provided safer and cleaner nuclear energy than the present Uranium/ Pu fuelled reactors. Over the last 10 years, a vast campaign of measurements has been initiated to bring the precision of neutron data for the key nuclei (232Th, 233Pa and 233U) at the level of those of the U- Pu cycle. This is the framework of these measurements, the energy dependent neutron induced fission cross section of 232Th and 233U has been measured from 1 to 7 MeV with a target accuracy lesser than 5 %. These measurements imply the accurate determination of the fission rate, the number of the target nuclei as well as the incident neutron flux impinging on the target, the latter has been obtained using the elastic scattering (n, p). The cross section of which is the very well known in a large neutron energy domain (~ 0,5 % from 1 eV to 50 MeV) compared to the 235U(n, f) reaction. This technique has been applied for the first time to the 232Th(n, f) and 233U(n, f) cases. A Hauser- Feshbach statistical model has been developed. It consists of describing the different decay channels of the compound nucleus 234U from 0,01 to 10 MeV neutron energy. The parameters of this model were adjusted in order to reproduce the measured fission cross section of 233U. From these parameters, the cross sections from the following reactions could be extracted: inelastic scattering 233U(n, n'), radiative capture 233U(n, γ) and 233U(n, 2n). These cross sections are still difficult to measure by direct neutron reactions. The calculated values allow to fill the lack of experimental data for the major fissile nucleus of the thorium cycle.
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Contributor : Virginie Mas <>
Submitted on : Thursday, July 16, 2009 - 3:35:16 PM
Last modification on : Thursday, January 11, 2018 - 6:12:50 AM
Long-term archiving on: : Tuesday, June 15, 2010 - 8:11:54 PM


  • HAL Id : tel-00404551, version 1



Cédric Grosjean. Mesure de la section efficace de fission induite par neutrons rapides des noyaux 232Th / 233U dans le cadre des cycles de combustiblesinnovants. Physique Nucléaire Théorique [nucl-th]. Université Sciences et Technologies - Bordeaux I, 2005. Français. ⟨tel-00404551⟩



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