[en] In this paper we describe a composite spatial grid spectral Green's function nodal method for the numerical solution of one-speed discrete ordinates deep penetration problems with isotropic scattering in X,Y-geometry. This method uses a rectangular coarse spatial grid, that is coincident with the material region distribution within the shielding structure. We first transverse integrate the S_N equations separately in the x- and y-coordinate directions inside each material region, and then we introduce flat approximations for the transverse leakage terms. Furthermore, we use a fine spatial grid to discretize each 'one-dimensional' S_N nodal equation. As the spatial directions are coupled by the transverse leakage terms, we use an explicit alternate direction technique to converge the numerical solution. In order to verify the offered method's accuracy, we present numerical results to a very simple model problem. (author)