Development of covariance capabilities in EMPIRE code
Abstract
The nuclear reaction code EMPIRE has been extended to provide evaluation capabilities for neutron cross section covariances in the thermal, resolved resonance, unresolved resonance and fast neutron regions. The Atlas of Neutron Resonances by Mughabghab is used as a primary source of information on uncertainties at low energies. Care is taken to ensure consistency among the resonance parameter uncertainties and those for thermal cross sections. The resulting resonance parameter covariances are formatted in the ENDF-6 File 32. In the fast neutron range our methodology is based on model calculations with the code EMPIRE combined with experimental data through several available approaches. The model-based covariances can be obtained using deterministic (Kalman) or stochastic (Monte Carlo) propagation of model parameter uncertainties. We show that these two procedures yield comparable results. The Kalman filter and/or the generalized least square fitting procedures are employed to incorporate experimental information. We compare the two approaches analyzing results for the major reaction channels on {sup 89}Y. We also discuss a long-standing issue of unreasonably low uncertainties and link it to the rigidity of the model.
- Authors:
- Publication Date:
- Research Org.:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Org.:
- Doe - Office Of Science
- OSTI Identifier:
- 939949
- Report Number(s):
- BNL-81624-2008-CP
R&D Project: 05055; KB0301041; TRN: US0806914
- DOE Contract Number:
- DE-AC02-98CH10886
- Resource Type:
- Conference
- Resource Relation:
- Conference: Covariance Workshop; Port Jefferson, New York ; 20080624 through 20080627
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; CROSS SECTIONS; EVALUATION; FAST NEUTRONS; NEUTRONS; NUCLEAR REACTIONS; RESONANCE
Citation Formats
Herman, M, Pigni, M T, Oblozinsky, P, Mughabghab, S F, Mattoon, C M, Capote, R, Cho, Young-Sik, and Trkov, A. Development of covariance capabilities in EMPIRE code. United States: N. p., 2008.
Web.
Herman, M, Pigni, M T, Oblozinsky, P, Mughabghab, S F, Mattoon, C M, Capote, R, Cho, Young-Sik, & Trkov, A. Development of covariance capabilities in EMPIRE code. United States.
Herman, M, Pigni, M T, Oblozinsky, P, Mughabghab, S F, Mattoon, C M, Capote, R, Cho, Young-Sik, and Trkov, A. 2008.
"Development of covariance capabilities in EMPIRE code". United States. https://www.osti.gov/servlets/purl/939949.
@article{osti_939949,
title = {Development of covariance capabilities in EMPIRE code},
author = {Herman, M and Pigni, M T and Oblozinsky, P and Mughabghab, S F and Mattoon, C M and Capote, R and Cho, Young-Sik and Trkov, A},
abstractNote = {The nuclear reaction code EMPIRE has been extended to provide evaluation capabilities for neutron cross section covariances in the thermal, resolved resonance, unresolved resonance and fast neutron regions. The Atlas of Neutron Resonances by Mughabghab is used as a primary source of information on uncertainties at low energies. Care is taken to ensure consistency among the resonance parameter uncertainties and those for thermal cross sections. The resulting resonance parameter covariances are formatted in the ENDF-6 File 32. In the fast neutron range our methodology is based on model calculations with the code EMPIRE combined with experimental data through several available approaches. The model-based covariances can be obtained using deterministic (Kalman) or stochastic (Monte Carlo) propagation of model parameter uncertainties. We show that these two procedures yield comparable results. The Kalman filter and/or the generalized least square fitting procedures are employed to incorporate experimental information. We compare the two approaches analyzing results for the major reaction channels on {sup 89}Y. We also discuss a long-standing issue of unreasonably low uncertainties and link it to the rigidity of the model.},
doi = {},
url = {https://www.osti.gov/biblio/939949},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Jun 24 00:00:00 EDT 2008},
month = {Tue Jun 24 00:00:00 EDT 2008}
}