The purpose of this investigation is to assess the basic areas of concern in the development of reactor shielding conceptual design calculations. A spherical shield model composed of two concentric spherical zones of low carbon steel and lead have been constructed to surround a Co-60 gamma point source. Two alternative configurations have been considered in the model computations. The numerical calculations have been performed using both the ANISN code and the DRP model computations together with the DLC 75-Bugle 80 data library. A resume of results for deep penetration in different shield materials with different packing densities is presented and analyzed. The results showed that the gamma fluxes attenuation is increased with increasing the packing density of the shield material which reflects its importance of considering it as a safety parameter in shielding design.