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Low-fidelity covariances for neutron cross sections on 57 structural and 31 heavy nuclei in the fast region

Technical Report ·
DOI:https://doi.org/10.2172/925823· OSTI ID:925823
 [1];  [1];  [1]
  1. Brookhaven National Laboratory (BNL), Upton, NY (United States)
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.
Research Organization:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP); USDOE Office of Science (SC), Nuclear Physics (NP)
DOE Contract Number:
AC02-98CH10886
OSTI ID:
925823
Report Number(s):
BNL-79985-2008-IR; KB0301041
Country of Publication:
United States
Language:
English