In this paper we describe a validation procedure for and results of streaming calculations for the Argonne National Laboratory gas-cooled fast reactor critical assemblies. The calculational approach for evaluating anisotropic diffusion theory methods is discussed in the context of a broader validation effort. A tentative procedure for converting from the three-dimensional physical unit cell to a one-dimensional model and for the generation of Benoist anisotropic diffusion coefficients in this one-dimensional model is described and analyzed. Based on the results, an alternate one-dimensional model and an alternate anistropic diffusion coefficient prescription are developed. After evaluating the alternate procedure, conclusions are drawn from the study.