Program - Brookhaven National Laboratory

angular distributions in the continuum double-differential particle emission spectra. The new evaluations
provide covariance matrices for all reaction cross sections up to 200 MeV to enable uncertainty analyses with
the data files. This covariance data are based on the nuclear model results in combination with relevant
experimental data using the Unified Monte Carlo Approach as implemented in the BEKED computer
code of KIT. General purpose data files for n+ 63,65 Cu for neutron energies from 1-10 −11 to 200 MeV
were generated in accordance with ENDF-6 format rules. The data files were checked with the standard
ENDF checker utilities and processed with NJOY/ACER for calculations with the MCNP code. Intensive
benchmarking of the files was then performed by analyses of integral experiments as available in the
SINBAD data base. These data files, produced in the frame of the European fusion program, finally will
be made available for inclusion in the JEFF nuclear data library. This work has been supported by Fusion
for Energy (F4E), Barcelona, under the grant contract F4E-FPA-168-01.
BF 4 11:40 AM
Evaluation of Tungsten Neutron Cross Sections in the Resolved Resonance Region 1
M. T. Pigni, L. C. Leal, M. E. Dunn, K. H. Guber
Nuclear Data and Criticality Safety, Reactor and Nuclear Systems Division, Oak Ridge National
Laboratory, P.O. Box 2008, Oak Ridge, TN, 37831-6170, USA
Following the series of recent measurements on tungsten isotopes performed at the GEel LINear Accelerator
(GELINA) by Lampoudis et al. [1] and the work presented at the PHYSOR 2012 conference in
Knoxville, Tennessee [2], the aim of this paper is to present resonance evaluations for total and capture
cross sections on 182,183,184,186 W in the neutron energy range of thermal energy up to several keV. The
Bayesian fitting method implemented in the R-matrix SAMMY code [3] was used to generate a comprehensive,
albeit still preliminary, set of neutron resonance parameters with related correlations and cross-section
covariance data. In the analyzed energy range, this work almost doubles the Resolved Resonance Region
(RRR) present in the latest US nuclear data library, ENDF/B-VII.1 [4]. Experimental conditions such as
resolution function, finite size sample, nonuniform thickness, and nuclide abundances of sample, multiple
scattering, self-shielding, normalization, background, and Doppler broadening were taken into account. In
thermal energy range, we utilized the recently published Atlas of Neutron Resonances [5] as well as the
tabulated neutron scattering lengths [6] as a source of information on scattering and capture cross sections,
and resonance integral. In view of the interest in tungsten metal for several distinct types of nuclear
applications, the emphasis of this paper is also on the performance of the calculated cross sections in criticality
benchmarks. In the current ENDF/B-VII.1 nuclear data library, the tungsten isotope evaluations
performed by Trkov et al. [7] were tested on the base of benchmark models taken from the SINBAD [8]
and the ICSBEP [9] compilation. We intend to repeat the analysis for a number of benchmarks involving
neutron flux in the intermediate energy range and, therefore, sensitive to the updated and extended resonance
evaluations for 182,183,184,186 W. 1 Notice: This abstract has been authored by UT-Battelle, LLC,
under contract DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government
retains and the publisher, by accepting the article for publication, acknowledges that the United States
Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the
published form of this manuscript, or allow others to do so, for United States Government purposes. The
U.S. Department of Energy Nuclear Criticality Safety Program sponsored the work that is presented in
this paper.
[1] C. Lampoudis et al., “Neutron Total and Capture Cross Section of Tungsten Isotopes,” ND2010: International
Conference on Nuclear Data for Science and Technology, Jeju Island, Korea (2010). [2] M. T. Pigni
et al.,“ 183 W Resonance Parameter Evaluation in the Neutron Energy Range up to 5 keV,” PHYSOR 2012
39