Covariance evaluation for actinide nuclear data in JENDL-4

Iwamoto, Osamu  ; Nakagawa, Tsuneo; Chiba, Satoshi; Otsuka, Naohiko*

Covariances of nuclear data in JENDL-4 have been evaluated. The covariance evaluations are basically based on available experimental data. The fission cross sections for 6 major actinides of U and Pu were evaluated simultaneously using experimental data of both cross sections and their ratios. The deduced covariance has correlations between the data of different nuclei. For minor actinide, covariances of the fission cross sections were obtained from evaluation using GMA code. For other many reaction cross sections, theoretical calculations with CCONE code were performed for cross section evaluations. The covariances were estimated using KALMAN code with sensitivities against model parameters. For resonance parameters and average number of fission neutrons, covariances were also evaluated.