Evaluation of the 235U resonance parameters to fit the standard recommended values
1 Institut de Radioprotection et de Sûrete Nucléaire, PSN-EXP/SNC/LNR, Fontenay-aux-Roses, France
2 CEA, DEN, Cadarache, Saint-Paul-les-Durance, France
3 Institute for Reference Materials and Methods Joint Research Center - European Commission Geel, Belgium
4 Universidade de Santiago de Compostela, Spain
5 Centre National de la Recherche Scientifique/IN2P3-IPN, Orsay, France
6 Rensselaer Polytechnic Institute, New York, USA
7 Los Alamos National Laboratory, New Mexico, USA
a e-mail: firstname.lastname@example.org
Published online: 13 September 2017
A great deal of effort has been dedicated to the revision of the standard values in connection with the neutron interaction for some actinides. While standard data compilation are available for decades nuclear data evaluations included in existing nuclear data libraries (ENDF, JEFF, JENDL, etc.) do not follow the standard recommended values. Indeed, the majority of evaluations for major actinides do not conform to the standards whatsoever. In particular, for the n + 235U interaction the only value in agreement with the standard is the thermal fission cross section. A resonance re-evaluation of the n + 235U interaction has been performed to address the issues regarding standard values in the energy range from 10−5 eV to 2250 eV. Recently, 235U fission cross-section measurements have been performed at the CERN Neutron Time-of-Flight facility (TOF), known as n_TOF, in the energy range from 0.7 eV to 10 keV. The data were normalized according to the recommended standard of the fission integral in the energy range 7.8 eV to 11 eV. As a result, the n_TOF averaged fission cross sections above 100 eV are in good agreement with the standard recommended values. The n_TOF data were included in the 235U resonance analysis that was performed with the code SAMMY. In addition to the average standard values related to the fission cross section, standard thermal values for fission, capture, and elastic cross sections were also included in the evaluation. This paper presents the procedure used for re-evaluating the 235U resonance parameters including the recommended standard values as well as new cross section measurements.
© The Authors, published by EDP Sciences, 2017
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