Speaker
Description
A resolved resonance region evaluation of 140,142Ce has been carried out by Oak Ridge National Laboratory. Requested by the US Nuclear Criticality Safety Program, this evaluation is based on recent high-resolution transmission and capture high-resolution measurements of natCe and 142Ce conducted at JRC-GEEL at the Geel Linear Accelerator facility, as well as recently measured thermal constants available from the EXFOR database [1]. Starting from the resonance parameters from the ENDF/B-VIII.0 library [2] and following a preliminary R-matrix analysis [3], an updated set of resonance parameters and corresponding covariance information was derived by the fit of these experimental datasets using the Reich-Moore approximation of the R-matrix theory as implemented in the SAMMY code system [4]. The resolved resonance region upper energy limit for 140Ce was kept at 200 keV while the 142Ce resonance region was extended from 13 to 26 keV. This new evaluation was found to be in good agreement not only with several integral quantities of interest to the reactor physics community, but also with the stellar Maxwellian-averaged cross section [5].
Acknowledgments
This work was supported by the U.S. Department of Energy (DOE) Nuclear Criticality Safety Program, which is funded and managed by the National Nuclear Security Administration for DOE.
- This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).}
References
[1] V. V. Zerkin, B. Pritychenko, “The experimental nuclear reaction data (EXFOR): Extended computer database and Web retrieval system,” Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 888, pp. 31-43 (2018).
[2] D. A. Brown et al, “ENDF/B-VIII.0: The 8th Major Release of the Nuclear Reaction Data Library with CIELO-project Cross Sections, New Standards and Thermal Scattering Data,” Nuclear Data Sheets, 148, pp. 1-142 (2018).
[3] C. W. Chapman, M. T. Pigni, K. Guber, “Progress on 140,142Ce Neutron Cross Section Resolved Resonance Region Evaluations,” ICNC2019-11th International Conference on Nuclear Criticality Safety, 15-20 September 2019 - Paris, France.
[4] N. M. Larson, “Updated user’s guide for Sammy: Multilevel R-matrix fits to neutron data using Bayes’ equations,” Tech. Rep. ORNL/TM-9179/R8, ENDF-364/R2, Oak Ridge National Laboratory (2008).
[5] B. Pritychenko, S. F. Mughabghab, “Neutron Thermal Cross Sections, Westcott Factors, Resonance Integrals, Maxwellian Averaged Cross Sections and Astrophysical Reaction Rates Calculated from the ENDF/B-VII.1, JEFF-3.1.2, JENDL-4.0, ROSFOND-2010, CENDL-3.1 and EAF-2010 Evaluated Data Libraries,” Nuclear Data Sheets, 113, pp. 3120-3144 (2012).