Studies of 54,56 Fe Neutron Scattering Cross Sections
Elastic and inelastic neutron scattering differential cross sections and γ-ray production cross sections have been measured on 54,56 Fe at several incident energies in the fast neutron region between 1.5 and 4.7 MeV. All measurements were completed at the University of Kentucky Accelerator Laboratory (UKAL) using a 7-MV Model CN Van de Graaff accelerator, along with the neutron production and neutron and γ-ray detection systems located there. The facilities at UKAL allow the investigation of both elastic and inelastic scattering with nearly mono-energetic incident neutrons. Time-of-flight techniques were used to detect the scattered neutrons for the differential cross section measurements. The measured cross sections are important for fission reactor applications and also for testing global model calculations such as those found at ENDF, since describing both the elastic and inelastic scattering is important for determining the direct and compound components of the scattering mechanism. The γ-ray production cross sections are used to determine cross sections to unresolved levels in the neutron scattering experiments. Results from our measurements and comparisons to model calculations are presented.
Evaluation of Neutron Reactions on Iron Isotopes for CIELO and ENDF/B-VIII.0
Abstract A 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.
Irradiation of structural materials in spallation neutron sources
In principle, intense spallation neutron sources can be used not only to irradiate materials (e.g. window materials) and to validate different target geometries/concepts, but also to irradiate structural materials (samples, pins or even full assemblies) in order to characterize their behavior under irradiation (in a fast neutron field). However, a question arises concerning the “representativity” of such irradiations to reproduce the conditions encountered in a typical fast reactor. The present paper documents an investigation aimed at understanding phenomena related to the representativity of an irradiation using an intense spallation source, with regards to neutron damage and Helium production. Two different designs of a spallation neutron source are considered. The first is an Intense Spallation Neutron Source (ISNS) proposed at CEA, France as a potential irradiation tool. The second is one of the current models for the TMT (Target for Material Testing) of the ADTF (Accelerator Driven Test Facility) program. In our calculations we used the MCNPX Version 2.1.5 Monte Carlo code.