LOW-FIDELITY COVARIANCES FOR NEUTRON CROSS SECTIONS ON 57 STRUCTURAL AND 31 HEAVY NUCLEI IN THE FAST REGION.

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

关键词: BUILDING MATERIALS;    CRITICALITY;    CROSS SECTIONS;    DATA COVARIANCES;    ENERGY RANGE;    EVALUATION;    FISSION PRODUCTS;    HEAVY NUCLEI;    NEUTRONS;    NUCLEAR REACTIONS;    OPTICAL MODELS;    SAFETY;    SENSITIVITY;    SENSITIVITY ANALYSIS;   

DOI  :  10.2172/925823
RP-ID  :  BNL--79985-2008-IR
PID  :  OSTI ID: 925823
Others  :  R&D Project: 05055
Others  :  Other: KB0301041
Others  :  TRN: US0802513

美国|英语

来源: SciTech Connect

【 摘 要 】

We produced a large set of neutron cross section covariances in the energy range of 5 keV-20 MeV. The present set of data on 57 structural materials and 31 heavy nuclei follows our earlier work on 219 fission product materials and completes our extensive contribution to the low-fidelity covariance project (307 materials). This project aims to provide initial, low-fidelity yet consistent estimates of covariance data for nuclear criticality safety applications. The evaluation methodology combines the nuclear reaction model code EMPIRE which calculates sensitivity to nuclear reaction model parameters, and the Bayesian code KALMAN that propagates uncertainties of the model parameters to cross sections. Taking into account the large scale of the project, only marginal reference to experimental data was made. The covariances were derived from the perturbation of several key model parameters selected by the sensitivity analysis. These parameters refer to the optical model potential, the level densities and the strength of the pre-equilibrium emission. This work represents the first attempt ever to generate nuclear data covariances on such a large scale.