Angular distribution uncertainty influence in a large sodium-cooled fast reactor with mixed-oxide fuel.

• The eigenvalue sensitivity to P 1 -moment is largest for 238 U , 56 Fe , and. 16 O. • The void reactivity sensitivity to P 1 -moment is largest for 56 Fe and. 23 Na. • A clear lack of data is shown excepting JENDL-5. • 16 O of ENDF/B-VIII.0 and 23 Na of TENDL-2021 have issues. • The eigenvalue P 1 -moment uncertainty for the top sources does not exceed 0.05%. Nuclear data uncertainties are considered a main limiting factor in proving safety of advanced reactors. A reasonable amount of available information should be applied to sensitivity and uncertainty analyses for this, and this work considers the influence of usually omitted angular distribution uncertainties. A sensitivity and uncertainty analysis of MOX3600 is conducted using Serpent. The angular distribution influence is assessed by applying covariances of the state-of-the-art libraries. The sensitivity analysis shows that quantifying the influence of higher-order Legendre moment uncertainties on the eigenvalue and void reactivity is of minor importance for MOX3600. The uncertainty analysis shows the P 1 -coefficients for 238 U and 16 O introduce uncertainties to the eigenvalue similar to 56 Fe and should be accounted for. A library comparison reveals TENDL-2021 and ENDF/B-VIII.0 introduce uncertainties of a few hundred pcm to the eigenvalue, and the data should be reassessed, while the other libraries give an uncertainty of several tens of pcm. [ABSTRACT FROM AUTHOR]