Program - Brookhaven National Laboratory

DC 5 5:00 PM
Thermal Neutron Cross Section Libraries for Silicon and Sapphire
F. Cantargi, J.R. Granada
Centro Atómico Bariloche and Instituto Balseiro (Comision Nacional de Energia Atomica)
Techniques such as neutron radiography, prompt gamma analysis and neutron diffractometry, use thermal
beams extracted from research nuclear reactors. In general, in low and medium power reactors where
there are no neutron guides, beams have high components of epithermal and fast neutrons and require
large shieldings. The employment of neutron filters improves the performance of these research facilities.
Typical materials that are used as a neutron filters are silicon and Al2O3 which is known as sapphire when
its structure is of the corundum type. Single crystals of these two materials are good neutron filters because
the dependence of their inelastic scattering cross section on neutron energy is such that fast neutrons and
most of the gamma radiation can be removed from the incident beam. Thermal cross section libraries at
room temperature for single crystals of sapphire and silicon were generated in ENDF and ACE format
using the NJOY nuclear data processing system. In both cases, a Debye spectrum was used to feed the
LEAPR module of NJOY. These cross sections were validated by comparing them with experimental cross
sections measured at the 25 MeV e − -LINAC based pulsed neutron source at Centro Atómico Bariloche.
Good agreement between calculations and experimental data was found for both neutron filters.
DC 6 5:15 PM
Neutron Cross Section Evaluation of Tantalum and Tungsten
Hyeong Il Kim, Cheol Woo Lee, and Young-Ouk Lee
Korea Atomic Energy Research Institute
The evaluation of neutron cross sections and covariances is presented for tungsten and tantalum which are
considered as a prime candidate of plasma facing materials in fusion reactors and/or a structural material
of Korea Helium Cooled Ceramic Reflector (HCCR) Test Blanket Module (TBM). The neutron cross
sections and energy and/or angular dependent neutron spectra from existing libraries such as ENDF/B-
VII.1, JENDL-4.0 and JEFF-3.1 show some discrepancies with the measured data available for tungsten
and tantalum. Moreover, the integral tests of neutron production from these libraries failed to reproduce
the leakage neutron measurements of OKTAVIAN. In response to these situations, the neutron cross
sections for 181 Ta and 180,182,183,184,186 W were newly evaluated and compared with the existing libraries
and the measured data available. This work aims at providing the reliable evaluation data and their
covariances above resonance region rather than a full energy range from 10 −5 eV to 20 MeV. The thermal
and resonance data were taken from the ENDF/B-VII.1, while the data above resonance region have been
calculated by using the EMPIRE code system that has been used to provide a number of consistent and
complete evaluations. The covariance data were generated through the KALMAN filtering implemented
in the EMPIRE system, which use the sensitivity matrices by variations of model parameters and the
available measurements.
DC 7 5:30 PM
New Resolved Resonance Region Evaluations for 63 Cu and 65 Cu to Support Nuclear
Criticality Safety Analyses
V. Sobes, B. Forget
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