Effect of Nuclear Data Covariances on Integral Experiment Design with Sensitivity and Uncertainty Analysis

摘要

The design of TEX experiments for criticality safety val-idation of Hanford waste models showed that the optimal experiment can vary with the nuclear data covariances em-ployed. The most significant differences between optimums computed with different libraries occurred when the systems had epithermal spectra. The covariance data of ENDF/B-Ⅶ.1 and ENDF/B-Ⅷ.0 have important differences in the interme-diate range for the (n,γ) cross section of ~56Fe and the fission cross section of~239Pu. Shifts in the neutron spectrum empha-sized different covariances and changed the optimal design. Meanwhile, thermal systems produced the same experimental designs with different covariance data, as the covariances are more consistent at this energy range. The 10-15% differences in computed ck have implications for criticality safety vali-dation, especially since covariance data are likely to change significantly with each library release. This suggests that ck should be used with care when designing benchmarks.