Neutron-induced fission cross sections ofPu242from 0.3 MeV to 3 MeV

Abstract

The majority of the next generation of nuclear power plants (GEN-IV) will work in the fast-neutron-energy region, as opposed to present day thermal reactors. This leads to new and more accurate nuclear-data needs for some minor actinides and structural materials. Following those upcoming demands, the Organisation for Economic Cooperation and Development Nuclear Energy Agency performed a sensitivity study. Based on the latter, an improvement in accuracy from the present 20% to 5% is required for the 242 Pu(n,f) cross section. Within the same project both the 240 Pu(n,f) cross section and the 242 Pu(n,f) cross section were measured at the Van de Graaff accelerator of the Joint Research Centre at the Institute for Reference Materials and Measurements, where quasimonoenergetic neutrons were produced in an energy range from 0.3 MeV up to 3 MeV. A twin Frisch-grid ionization chamber has been used in a back-to-back configuration as fission-fragment detector. The 242 Pu(n,f) cross section has been normalized to three different isotopes: 237 Np(n,f), 235 U(n,f), and 238 U(n,f). A comprehensive study of the corrections applied to the data and the uncertainties associated is given. The results obtained are in agreement with previous experimental data at the threshold region up to 0.8 MeV. The resonance-like structure at 0.8 to 1.1 MeV, visible in the evaluations and in most previous experimental values, was not reproduced with the same intensity in this experiment. For neutron energies higher than 1.1 MeV, the results of this experiment are slightly lower than the Evaluated Nuclear Data File/B-VII.1 evaluation but in agreement with the experiment of Tovesson et al. (2009) as well as Staples and Morley (1998). Finally, for energies above 1.5 MeV, the results show consistency with the present evaluations.

Fast-neutron-induced fission of242Pu atnELBE

“…Larger deviations to the Weigmann data [20] in the order of 5.4% are present especially in the plateau region between 1.2 MeV and 5 MeV. The recently published data of Salvador-Castiñeira et al [3] are also below this cross section ratio. This is of special interest, because the current European evaluation JEFF 3.2 (see Ref.…”

“…[3]. Results of measurements at the Los Alamos National Laboratory by Tovesson et al [4] and at the Joint Research Center Geel by Salvador-Castiñeira et al [3] were published recently and tend to be lower than present evaluated nuclear data [5].…”

Determination of the fast-neutron-induced fission cross-section of 242Pu at nELBE

“…Larger deviations to the Weigmann data [21] in the order of 5.4% are present especially in the plateau region between 1.2 MeV and 5 MeV. The recently published data of Salvador-Castiñeira et al [3] are also below the Weigmann cross section ratio. This is of special interest, because the current European evaluation JEFF 3.2 (see Ref.…”

“…A brief summary of the available experimental data acquired since then is given in Ref. [3]. Results of measurements at the Los Alamos National Laboratory by Tovesson et al [4], at the Joint Research Center Geel by Salvador-Castiñeira et al [3] and at the National Physical Laboratory of the United Kingdom in Teddington by Matei et al [5] have been recently published and tend to be lower than the current european data evaluation JEFF 3.2 [6].…”

Fission cross-sections, prompt fission neutron and γ-ray emission in request for nuclear applications

“…More details are given in Refs. [5,6]. The incident neutron energy range covered was from 0.3 MeV to 3 MeV.…”