The aim of this work is to develop an equation that links the concentration of radiation activity measured practically with the radioactivity of radioactive waste which is measured theoretically. The purpose is to develop a working methodology for the characterization of radioactive materials for drums containing waste which used for storage, transport and treatment of waste and the determine radiation dose rate which is necessary to protect workers. Characterization of drums containing radioactive waste by measuring them (without opening) provides general ease to determine the method of work and the necessities of radiation protection. A drum characterization system (gamma spectrometry) was used to characterize drums containing radioactive waste. The concentration of radiation activity was calculated by taking several models of radioactive waste (samples and drums) and describing them in the gamma analysis system.