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Covariance Calculations Methodology at BNL: Status and Perspectives

This document discusses the methodologies for covariance calculations developed at Brookhaven National Laboratory (BNL) and Los Alamos National Laboratory, highlighting their application to various isotopes and parameters. The methodology focuses on uncertainty parameters, sensitivity analysis, and optimal recursive data processing algorithms. It covers the specific case of thermal neutron capture resonance integral parameters and emphasizes the use of models such as Hauser-Feshbach and pre-equilibrium reactions. The report aims to optimize covariance analysis and improve cross-section uncertainties and correlations for nuclear data.

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Covariance Calculations Methodology at BNL: Status and Perspectives

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  1. Covariance data: Status and Perspective at BNL D. Rochman, M. W. Herman, P. Obložinský National Nuclear Data Center, Brookhaven National Laboratory & T. Kawano T-16, Los Alamos National Laboratory

  2. Methodology for covariance calculations at BNL

  3. General Procedure Optional: Thermal neutron capture Resonance Integral Parameters Uncertainty Parameters Sensitivity an optimal recursive data processing algorithm • Fast Region • Hauser Feshbach • Pre-equilibrium • -… • Resonance Region • Breit Wigner • Reich Moore RIPL & Parameter uncertainty adjustment or Cross Section Uncertainties and Cross Section Correlations Models and parameters KALMAN Filter

  4. General Procedure • Up to today, this procedure was applied to: • Gd-152 to Gd-160 from 35 to 500 parameters (R3+URR+FaR) • Am-241 790 parameters (R3+URR) • Tc-99 1600 parameters (R3+URR) • U-233, 234, 236 from 250 to 3850 parameters (R3+URR)

  5. 152Gd(n,g): Variance

  6. 152Gd(n,g): Correlation Energy-Energy Energy (MeV) 10-5 10-7 0.001 0.1 10 Energy (MeV)

  7. 155Gd(n,g): Variance

  8. 157Gd(n,g): Correlation Energy-Energy Energy (MeV) 10-5 10-7 0.001 0.1 10 Energy (MeV)

  9. 241Am(n,f): Variance

  10. 241Am(n,f), 234U(n,f): Correlation Energy-Energy 10-5 0.001 10-7 10-7 0.001 10-5 Energy (MeV) Energy (MeV) 241Am(n,f) 234U(n,f)

  11. 236U(n,f) and 99Tc(n,g) 10-7 10-5 0.001 10-5 0.001 10-7 236U(n,f) 99Tc(n,g) Energy (MeV) Energy (MeV)

  12. Production Schedule • May 2006 : proof of principle on 8 Gd isotopes, 241Am, 99Tc, 233U, 234U, 236U • End 2006 : Codes ready and running on a 10-nodes cluster • Mid 2007 : Production of covariances for selected materials • End 2007 : Low fidelity covariances for ENDF/A (if project approved) Covariance matrix available -in any multi-group representation -at any temperatures -in tabulated form or MF33 format

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