Generation of fission yield covariances to correct discrepancies in the nuclear data libraries

We chose to work with the PWR fuel rod model of the REBUS international program to test the new covariances, since experimental uncertainties on several concentrations are available. We propagated the original and updated fission yield covariances using a sampling approach and we quantified the uncertainty of keff and nuclide densities in the chosen burnup problem. The response uncertainty for keff and nuclide densities showed a sharp drop when using the new set of fission yield covariance matrices.