Covariance Evaluation Methodology for Neutron Cross Sections.

Herman, M. ; Arcilla, R. ; Mattoon, C. M. ; Mughabghab, S. F. ; Oblozinsky, P.

Technical Information Center Oak Ridge Tennessee

关键词: Neutrons;    Cross sections;    Fast neutrons;    Production;    Resonance;   

RP-ID  :  DE2008939948

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

We present the NNDC-BNL methodology for estimating neutron cross section covariances in thermal, resolved resonance, unresolved resonance and fast neutron regions. The three key elements of the methodology are Atlas of Neutron Resonances, nuclear reaction code EMPIRE, and the Bayesian code implementing Kalman filter concept. The covariance data processing, visualization and distribution capabilities are integral components of the NNDC methodology. We illustrate its application on examples including relatively detailed evaluation of covariances for two individual nuclei and massive production of simple covariance estimates for 307 materials. Certain peculiarities regarding evaluation of covariances for resolved resonances and the consistency between resonance parameter uncertainties and thermal cross section uncertainties are also discussed.