Actinide ENDF/BVII cross section evaluations and validation testing

We describe advances made recently at Los Alamos for ENDF/B-VII, and for future ENDF releases, of actinide cross section evaluations. Using americium as an illustrative example, we describe recent experiments that have largely confirmed the nuclear theory predictions that were the basis for the ENDF/B-VII.0 data for these americium reactions. The goal of this paper is to highlight some of the open issues in our understanding of the actinide nuclear data - especially for fast reactor applications - and show examples of how experiment, theory, and integral data validation has advanced our understanding. We will also describe the usage of these data in MCNP and SN radiation transport simulations of various integral critical systems, for both criticality and for transmutation reaction rates. (authors)