Simplified P$_N$ Equations for Nonclassical Transport with Isotropic   Scattering
  An asymptotic analysis is used to derive a set of diffusion approximations to the nonclassical transport equation with isotropic scattering. These approximations are shown to reduce to the simplified P$_N$ equations under the assumption of classical transport, and therefore are labeled nonclassical SP$_N$ equations. In addition, the nonclassical SP$_N$ equations can be manipulated into a classical form with modified parameters, which can be implemented in existing SP$_N$ codes. Numerical results are presented for an one-dimensional random periodic system, validating the theoretical predictions. 
R. Vasques and R.N. Slaybaugh
nucl-th math-ph math.MP