  This article describes the production of primordial He4 nuclei in an
inhomogeneous universe. The baryon distribution is spherically symmetric and
consists of a high density inner region and a low density outer region. As the
temperature decreases neutrons diffuse to the outer region until they are
homogeneously distributed, and protons may be redistributed depending on how
fast diffusion occurs. Nucleosynthesis occurs earlier in the inner region and
neutrons diffuse back to that region. The rapidity of diffusion determines how
much He4 is ultimately produced.
