Rhenium resonance parameters from neutron capture and transmission measurements in the energy range 0.01 eV to 1 keV

• Published in: Progress in nuclear energy (New series) Vol. 99; pp. 59 - 72
• Main Authors: Epping, B.E., Leinweber, G., Barry, D.P., Rapp, M.J., Block, R.C., Donovan, T.J., Danon, Y., Landsberger, S.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-08-2017; Elsevier BV
• Subjects: 185Re; 187Re; Absorption cross sections; Bayesian analysis; Capture yield; Energy transmission; Flight paths; Integrals; Isotopes; LINAC; Linear accelerators; Multilevel; Neutrons; NNL; Nuclear capture; Nuclear energy; Nuclear reactors; Parameter uncertainty; Resonance integral; Resonance parameters; Rhenium; RPI; Statistical analysis; Statistical methods; Thermal cross section; Transmission; Uncertainty analysis; Resonance parameters; LINAC; Capture yield; Transmission; RPI; Rhenium; 185Re; Resonance integral; NNL; Thermal cross section; 187Re
• ISSN: 0149-1970; 1878-4224
• DOI: 10.1016/j.pnucene.2017.04.015

Rhenium is a refractory metal with potential uses in nuclear reactor applications, particularly those at very high temperatures. Measurements have been made using natural samples. Natural rhenium consists of two isotopes: 185Re (37.40%) and 187Re (62.60%). The electron linear accelerator (LINAC) at the Rensselaer Polytechnic Institute (RPI) Gaerttner LINAC Center was used to explore neutron interactions with rhenium in the energy region from 0.01 eV to 1 keV. Neutron capture and transmission measurements were performed by the time-of-flight technique. Two transmission measurements were performed at flight paths of 15 m and 25 m with 6Li glass scintillation detectors. The neutron capture measurements were performed at a flight path of 25 m with a 16-segment sodium iodide multiplicity detector. Resonance parameters were extracted from the data using the multilevel R-matrix Bayesian code SAMMY. A table of resonance parameters and their uncertainties is presented. The uncertainties in resonance parameters were propagated from a number of experimental quantities using a Bayesian analysis. Uncertainties were also estimated from fitting each Re sample measurement individually. The measured neutron capture resonance integral for 185Re is (4 ± 1)% larger than ENDF/B-VII.1. The capture resonance integral for 187Re is (3 ± 1)% larger than ENDF/B-VII.1. Other findings from these measurements include: a decrease in the thermal capture cross section for 185Re of (2 ± 2)% from ENDF/B-VII.1; a decrease in the thermal capture cross section for 187Re of (3 ± 4)% from ENDF/B-VII.1; a decrease in the thermal total cross section for 185Re of (2 ± 2)% from ENDF/B-VII.1; and a decrease in the thermal total cross section for 187Re of (6 ± 5)% from ENDF/B-VII.1. Considering the uncertainties, none of the indicated changes in thermal cross sections represents a statistically significant change from ENDF/B-VII.1.
•Neutron transmission and capture yield measurements using natural rhenium samples in the energy range of 0.01 eV–1 keV.•Data results were fitted using SAMMY to obtain improved resonance parameters.•Thermal cross sections, resonance integrals, and neutron width distributions were assessed.