Validation des bases de données de sections efficaces par l'utilisation d'un spectromètre à temps de ralentissement au plomb entre 0,1 eV et 30 keV. Méthodologie - Résultats

Abstract : Projects dealing with future reactors consider using new fuels and demonstrate the ability of such reactors to incinerate nuclear waste. These projects have triggered new interest in cross section measurements for a large number of elements over a wide energy range. In some cases, existing data bases disagree, making new measurements necessary. Complete high resolution cross section measurements require both large beam times, and large data analysis times. However, a good capture cross section profile between 0,1eV and 30keV can be obtained using a lead slowing down time spectrometer in association with a pulsed neutron generator. Such measurements have been performed at the Institut des Sciences Nucléaires (ISN) at Grenoble. The neutron flux is measured with a 233U fission detector and an 3He gas detector and the results are compared to very precise Monte Carlo simulations (MCNP code) of the experimental set up, using several data bases for lead. We have shown that, with this method, the scattering cross section on lead can be tested with a precision of the order of 1,5%. Capture rates, measured with a CeF3 scintillator coupled to a photomultiplier, are compared to simulation results using different data bases for the samples. Reference materials (Au, Ag, In, Ta) have been measured, materials that are present in the core of reactors (232Th, U, 99Tc) have been tested, as well as structure materials (W, Mo, Ni, Mn). Data bases are validated with a precision of 5%. Measurements done for different target thicknesses complete the data. Areas of agreement and disagreement between experimental results and data bases are systematically described. Finally, a correction table for the capture cross sections extracted from the appropriate data base is obtained and presented, for some elements.
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Theses
Nuclear Experiment [nucl-ex]. Université Joseph-Fourier - Grenoble I, 2001. French


https://tel.archives-ouvertes.fr/tel-00000933
Contributor : Luc Perrot <>
Submitted on : Friday, December 21, 2001 - 4:50:07 PM
Last modification on : Thursday, July 27, 2006 - 11:49:21 AM

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Luc Perrot. Validation des bases de données de sections efficaces par l'utilisation d'un spectromètre à temps de ralentissement au plomb entre 0,1 eV et 30 keV. Méthodologie - Résultats. Nuclear Experiment [nucl-ex]. Université Joseph-Fourier - Grenoble I, 2001. French. <tel-00000933>

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