Status of D(n,n)D Elastic Scattering Data

An overview is presented of activities to reduce uncertainties in the neutron differential elasticscattering cross-section data for deuterium. The main subject is the amount of backscatter at energies below 3.2 MeV observed in different differential cross-section measurements and represented in various evaluations, together with the reactivity impact this has in simulations of relevant integral experiments. The scope encompasses fundamental nuclear-data measurements, three-body nuclear-theory calculations, evaluated nuclear-data libraries and associated data processing, and the simulation of critical experiments involving heavy water. The reactivity impact is illustrated using MCNP5 simulations of ZED-2 and other experiments. The simulations incorporate refinements, such as preparation of thermal-scattering-law data files for D-in-D2O to the nearest ºC using NJOY99 and inclusion of photonuclear data to account for the reactivity effects of (gamma,n) reactions. The analysis indicates that the energy grid ENDF/B-VII.0 uses to represent the angular distributions for deuterium elastic scattering should be refined. Additional work is planned, including new angular-distribution measurements at the GELINA facility at IRMM in Geel, Belgium using a CD2 (deuterated polyethylene) sample provided by AECL and scaling of new nuclear-theory-based elastic-scattering cross-section results. Preliminary GELINA findings using a C6D6 target indicate less backscatter than predicted by ENDF/B-VII.0, in contrast to the nuclear-theory results. It is expected that completion of the planned work will reduce the uncertainty of the energy-angle distributions for deuterium elastic scattering and contribute to an improved deuterium evaluation in a future release of ENDF/B-VII.

KOZIER K.;  ROUBTSOV D.;  RAO R.;  SVENNE J. P.;  CANTON L.;  PLOMPEN Arjan;  STANOIU Mihai;  NANKOV Nikolay;  ROUKI Chariklia; 

2011-01-26

American Nuclear Society

JRC61769

http://www.new.ans.org/store/i_700356,    https://publications.jrc.ec.europa.eu/repository/handle/JRC61769,