Covariance data in the fast neutron region

The report has been issued by WPEC Subgroup 24, whose mission was to review methodologies and develop tools for producing data uncertainties (covariance data) in the fast neutron energy region. These involve both least-squares procedures and, more recently, stochastic (Monte Carlo) techniques. Since all modern approaches depend on extensive usage of nuclear reaction modelling, consideration is given to recent attempts to determine the extent to which nuclear modelling deficiencies contribute to the uncertainty of contemporary nuclear data evaluation.