239Pu nuclear data improvements in thermal and epithermal neutron rangesD. Bernard, E. Fort, A. Courcelle, A. Santamarina, G. Noguere, O. Litaize and C. Vaglio-Gaudard
CEA Cadarache, Bd 230, DEN/CAD/DER/SPRC/LEPh, 13108 Saint-Paul-lez-Durance Cedex, France
Published online: 21 May 2008
The analysis of keff multiplicative factor of 100%-MOx cores and plutonium solutions showed a systematic discrepancy between calculation and experiment. The aim of this paper is to propose an improved version of the JEFF-3.1 239Pu evaluation in the low-energy neutron range. We propose here slight modifications of the evaluation file, consistent with the uncertainties of differential data measurements in sub-thermal/thermal and epithermal ranges, namely: modifications of the sub-thermal fission, capture and total cross sections, and a revised evaluation of νp from sub-thermal up to 20 eV using a phenomenological formalism. The proposed modifications are described and tested against integral measurements.
© CEA 2008