LOW-FIDELITY CROSS SECTION COVARIANCES FOR 219 FISSION PRODUCTS IN THE FIRST NEUTRON REGION.

PIGNI,M.T. ; HERMAN, M. ; OBLOZINSKY, P. ; ROCHMAN, D.

关键词: CRITICALITY;    CROSS SECTIONS;    DATA COVARIANCES;    ENERGY RANGE;    FISSION;    FISSION PRODUCTS;    NEUTRONS;    NUCLEAR REACTIONS;    SAFETY;    SENSITIVITY;    SENSITIVITY ANALYSIS COVARIA;   

DOI  :  10.2172/915433
RP-ID  :  BNL--79261-2007-IR
PID  :  OSTI ID: 915433
Others  :  R&D Project: 05055
Others  :  Other: KB0301041
Others  :  TRN: US0804982

美国|英语

来源: SciTech Connect

【 摘 要 】

An extensive set of covariances for neutron cross sections in the energy range 5 keV-20 MeV has been developed to provide initial, low-fidelity but consistent uncertainty data for nuclear criticality safety applications. The methodology for the determination of such covariances combines the nuclear reaction model code EMPIRE, which calculates sensitivity to nuclear reaction model parameters, and the Bayesian code KALMAN to propagate uncertainty of the model parameters to cross sections. Taking into account the large scale of the project (219 fission products), only partial reference to experimental data has been made. Therefore, the covariances are, to a large extent, derived from the perturbation of several critical model parameters selected through the sensitivity analysis. These parameters define optical potential, level densities and pre-equilibrium emission. This work represents the first attempt ever to generate nuclear data covariances on such a scale.