We use an unresolved transition array model to investigate the opacities of high-Zmaterials and their mixtures which are of interest to indirect-drive inertial confinement fusion hohlraum design. In particular, we report on calculated opacities for pure Au, Gd, and Sm, as well as Au–Sm and Au–Gd mixtures. Our results indicate that mixtures of Au–Gd and Au–Sm can produce a significant enhancement in the Rosseland mean opacity. Radiation hydrodynamics simulations of Au radiation burnthrough are also presented, and compared with NOVA experimental data. ©1997 American Institute of Physics.