Evaluation of neutron induced reactions on ⁵⁶Fe with CONRAD

Abstract

The evaluation of the 56Fe neutron induced reactions is currently ongoing at the CEA-Cadarache using the code CONRAD, with the goal to cover the whole energy range from the Resolved Resonance Region to the continuum and estimate the corresponding uncertainties and covariance matrices. Some first results and issues occurred from this work are presented and discussed here, more specifically on the analysed transmission and capture data in the Resolved Resonance Region, as well as the optical and statistical model calculations in the fast neutron energy range.

Summary Report of the IAEA Consultants' Meeting of International Nuclear Datas Evaluation Network (INDEN) on the Evaluated Data of Structural Materials

“…The motivation behind this work was that issues occurred with the 56 Fe(n, γ) reaction within the CIELO project [3], leading to important implementations in the evaluation of the 56 Fe(n,γ) reaction in the latest ENDF/B-VIII.0 library. More specifically, an artificial background was added in the energy region 10 eV -100 keV, which seems to be validated by integral measurements [3][4]. Furthermore, the results above 860 keV based on experimental data from the RPI [5] showed an increase of (n, γ) at ~850 keV, where the (n,inl) channel opens.…”

“…The status of copper evaluations was reviewed and results of new Copper neutron leakage benchmark (50 cm copper cube) from CV Rez discussed [4]. It was noted that the JEFF-3.3 evaluation performed poorly in the whole energy range, the ENDF/B-VIII.0 evaluation underestimates the data above 4 MeV, while the JENDL-4 evaluation overestimates the data below 4 MeV.…”

“…The previously mentioned issues need physical interpretation, and this was attempted via the Direct Radiative Capture mechanism. Finally, from transmission measurements, it was shown that some valleys between resonances are not well described in the Resolved Resonance Region [4,5], pointing to a need of increasing the total cross section below the opening of the (n,inl) channel, which could be mainly attributed to the elastic channel contribution of 56 Fe or minor isotopes and potentially some small contribution of the direct capture mechanism.…”