Improvement of covariance data for fast reactors

not registered; not registered

We estimated covariances of the JENDL-3.2 data on the nuclides and reactions needed to analyze fast-reactor cores for the past three years, and produced covariance files. The present work was undertaken to re-examine the covariance files and to make some improvements. The covariances improved are the ones for the inelastic scattering cross section of O, the total cross section of Na, the fission cross section of U, the capture cross section of U, and the resolved resonance parameters for U. Moreover, the covariances of U data were newly estimated by the present work. The covariances obtained were compiled in the ENDF-6 format.