The CIELO collaboration: Progress in international evaluations of neutron reactions on Oxygen, Iron, Uranium and Plutonium

The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear technologies – 16O, 56Fe, 235,8U and 239Pu – with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality

Determination of double-differential neutron emission cross sections of "5"1V in the energy range from 8 MeV to 14 MeV using a DD neutron source

In neutron scattering measurements using a DD neutron source, above an incident neutron energy of about 8 MeV, the spectra of scattered breakup neutrons and inelastically scattered monoenergetic neutrons are superimposed on one another. The disturbing breakup scattering fraction can be subtracted after having been calculated by a realistic Monte Carlo simulation of the scattering geometry and processes. The data for such a calculation are checked and adjusted using an additional pure breakup neutron source based on the "4He(d,np)"4He reaction. By proper subtraction of the breakup fractions, double-differential cross sections can be obtained for neutron emission energies down to 1.5 MeV. This procedure is described for neutron scattering on "5"1V. The results are compared with those obtained using a monoenergetic 14 MeV neutron source and with the ENDF/B-VI evaluation. Furthermore, the results are compared with those obtained using also the same non-monoenergetic neutron source but a quite different measurement arrangement and similar data analysis procedure. The advantages of the procedure established at the PTB as well as shortcomings and possible improvements are discussed. (orig.)Available from TIB Hannover: RO 8345(46) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

New

The Collaborative International Evaluated Library Organisation (CIELO) aims to provide revised and updated evaluations for 239Pu, 238,235U, 56Fe, 16O, and 1H through international collaboration. This work, which is part of the CIELO project, presents the initial results for the evaluation of the 56Fe isotope, with neutron-incident energy ranging from 0 to 20 MeV. The 56Fe(n,p) cross sections were fitted to reproduce the ones from IRDFF dosimetry file. Our preliminary file provides good cross-section agreements for the main angle-integrated reactions, as well as a reasonable overall agreement for angular distributions and double-di_erential spectra, when compared to previous evaluations

New 56Fe Evaluation for the CIELO project

The Collaborative International Evaluated Library Organisation (CIELO) aims to provide revised and updated evaluations for 239Pu, 238,235U, 56Fe, 16O, and 1H through international collaboration. This work, which is part of the CIELO project, presents the initial results for the evaluation of the 56Fe isotope, with neutron-incident energy ranging from 0 to 20 MeV. The 56Fe(n,p) cross sections were fitted to reproduce the ones from IRDFF dosimetry file. Our preliminary file provides good cross-section agreements for the main angle-integrated reactions, as well as a reasonable overall agreement for angular distributions and double-di_erential spectra, when compared to previous evaluations

Evaluation of Neutron Reactions on Iron Isotopes for CIELO and ENDF/B-VIII.0

International audienceA new suite of evaluations for 54,56,57,58 Fe has been developed in the framework of the CIELO international collaboration. New resolved resonance ranges were evaluated for 54 Fe and 57 Fe, while modifications were applied to resonances in 56 Fe. The low energy part of the 56 Fe file is almost totally based on measurements. At higher energies in 56 Fe and in the whole fast neutron range for minor isotopes the evaluation consists of model predictions carefully adjusted to available experimental data. We also make use of the high quality and well experimentally-constrained dosimetry evaluations from the IRDFF library. Special attention was dedicated to the elastic angular distributions, which were found to affect results of the integral benchmarking. The new set of iron evaluations was developed in concert with other CIELO evaluations and they were tested together in the integral experiments before being adopted for the ENDF/B-VIII.0 library

New 56

The Collaborative International Evaluated Library Organisation (CIELO) aims to provide revised and updated evaluations for 239Pu, 238,235U, 56Fe, 16O, and 1H through international collaboration. This work, which is part of the CIELO project, presents the initial results for the evaluation of the 56Fe isotope, with neutron-incident energy ranging from 0 to 20 MeV. The 56Fe(n,p) cross sections were fitted to reproduce the ones from IRDFF dosimetry file. Our preliminary file provides good cross-section agreements for the main angle-integrated reactions, as well as a reasonable overall agreement for angular distributions and double-di_erential spectra, when compared to previous evaluations

The CIELO collaboration: Progress in international evaluations of neutron reactions on Oxygen, Iron, Uranium and Plutonium

The CIELO collaboration has studied neutron cross sections on nuclides that significantly impact criticality in nuclear technologies – 16O, 56Fe, 235,8U and 239Pu – with the aim of improving the accuracy of the data and resolving previous discrepancies in our understanding. This multi-laboratory pilot project, coordinated via the OECD/NEA Working Party on Evaluation Cooperation (WPEC) Subgroup 40 with support also from the IAEA, has motivated experimental and theoretical work and led to suites of new evaluated libraries that accurately reflect measured data and also perform well in integral simulations of criticality