Program - Brookhaven National Laboratory

Poster Session
PR 1
Analysis of the Quality of Evaluated Data for Most Relevant Reactions of MYRRHA
C.J. Diez, O. Cabellos, J.S. Martinez, Universidad Politecnica de Madrid (UPM), c José Gutiérrez
Abascal 2, 28006, Madrid, Spain. A. Stankovskiy, G. Van den Eynde, SCK-CEN, Boeretang 200,
BE-2400 MOL, Belgium. J. Heyse, P. Schillebeeckx, Nuclear Physics Unit, EC-JRC-IRMM, Retieseweg
111, B - 2440 Geel , Belgium.
A typical way to quickly estimate the uncertainty induced by cross-sections in a neutronic calculation using
MCNP is to look at the effect of changing the full cross section library from one to another. Typically, the
well-known and available libraries ENDF/B-6 or 7, JEFF 3.x and JENDL-3 or 4 are being used. However,
as these libraries tend to use the same experiments and even the same evaluations, there is worry for a
“common mode failure”. This exercise has been done for MYRRHA together with more extensive work
using covariance data available in the JENDL-4.0 library. Based on this, a list of isotopes and reaction
channels that are of importance for MYRRHA have been identified. Then, a study of the origin of the
relevant data for this application will be performed. The study will compare nuclear data libraries, look
into which evaluation methodology and experimental data have been used, and how these experimental
data have been combined, and shared between libraries. Under the light of these results, the objective is to
propose how these libraries could be improved with possible recommendations, additional measurements or
new analysis. The research leading to these results has received funding from the European Atomic Energy
Community’s Seventh Framework Programme [FP7/2007-2013] under grant agreement no. 249671, (FP7-
EURATOM-FISSION-2009:Project ANDES/249671). Also, it has been partially supported by “Ministerio
de Educación (Ministry of Education)” of Spain through the FPU Program for teaching and researching
formation (Programa de Formación de Profesorado Universitario) under grant AP2009-1801
PR 2
Pinning Down Uncertainties via Systematic Trends
M. G. Bertolli, T. Kawano, H. Little, Theoretical Division, Los Alamos National Laboratory, Los Alamos,
NM 87545, USA.
The calculation of neutron capture cross sections in a statistical Hauser-Feshbach [1] method has proved successful
in numerous astrophysical applications. Of increasing interest is not only the calculated Maxwellian
averaged cross sections (MACS) itself, but the associate uncertainty. Aspects of a statistical model that
introduce a large amount of uncertainty are the level density model, γ-ray strength function parameter,
and the placement of Elow – the cut-off energy below which the Hauser-Feshbach method is not applicable.
The pre-equilibrium process has no impact on MACS for astrophysical energies, and so uncertainties for
this are neglected. Utilizing the Los Alamos statistical model code CoH3 [2] we investigate the appropriate
treatment of these sources of uncertainty via systematics of nuclei in a local region for which experimental
or evaluated data is available. We will demonstrate the results of the investigation as a meaningful prescription
in the statistical treatment of nuclei for which there exists little or no evaluated data for capture
reactions, as well as for some nuclei for which data in the various evaluated libraries exhibits large differences.
In order to show the impact of uncertainty analysis on nuclear data for astrophysical applications,
these new uncertainties will be propagated through the nucleosynthesis code NuGrid [3]. This work was
supported by the U.S. Department of Energy under contract DE-AC52-06NA25396.
[1] W. Hauser and H. Feshbach, Phys. Rev. 87, 366 (1952). [2] T. Kawano, P. Talou, M. B. Chadwick,
T. Watanabe, J. Nucl. Sci. Technol., 47, 462 (2010). [3] F. Herwig, M. E. Bennet, S. Diehl, C. L. Fryer,
261