Because of great concern about the effect of resonance interactions on the Doppler-effect calculations, extensive studies have been made for various dilute systems. A simplified method which allows the simultaneous occurrence of more than one type of interference has been developed to calculate the temperature-dependent effective cross sections. Consequently, the numerical work involved is simplified considerably. Calculations have been made for typical PU239-U238, U235-U238, and Pu239-U238-Pu240 systems. The results of these calculations seem to indicate that the resonance interference will substantially increase the negative Doppler effect of the system as compared to the case where resonance interferences are ignored.