[en] The method of cyclic activation analysis is selective in enhancing the signal-to-noise ratio of short-lived radionuclides of interest and suppresses the longer lived nuclides in the matrix when compared with the conventional one-shot irradiation and counting sequence. The important features of the cyclic activation system available at the University of London Reactor Centre, are briefly outlined. The method can be used to determine in the same experiment, the half-life of the radionuclides of interest in order to confirm identification in complex γ-ray spectra and thus making the determination of the yield of short-lived fission products possible. Results of experiments undertaken in the detection and measurement of short-lived fission products from natural uranium and thorium are discussed. (Auth.)