“…Many approximations and interpretations for estimating these quantities are available in the litera ture. Different formulas have been cited by Paletin(12).The study of effective values of these quantities is not of a great concern in the present work. Instead, the localized variation of neutron flux in the medium and along the wall of the cavity will be discussed in detail.Assume that the diffusion approximation is valid every where in the medium including boundary points.…”