[en] The study of resonance self-shielding in heterogeneous media has direct applications on the design and analyses of fast neutronic problems. Integral reaction rate measurements using resonance detector foils require a self shielding correction to account for the spatial shielding effect of the foil. Typical experimental correction technique based on extrapolating measurements for several foils of different thicknesses can lead to uncertainties in the experimental data. A new analysis method was developed to evaluate the foil correction factors of resonance detectors in fast neutron spectra. The new analysis method is based on an iterative treatment of the integral transport equation that describes the single and multiple scattering processes inside the detector foil. The foil correction factor at each experimental position is related to the impinging neutron spectrum by combining the resonance self-shielding factors of individual Doppler broadened resonances with the multigroup reaction rates obtained from the results of a two-dimensional diffusion theory calculation. Another important subject concerning heterogeneous resonance self-shielding occurs near a zone interface that separates regions of a different material compositions. Such transition was observed experimentally in the capture data of ²³⁸U near the FBBF transformer-blanket interface