[en] Radioactive waste assay system was designed, manufactured to exclude worker's exposure and to measure the individual nuclide's activity in homogeneous and non-homogeneous waste drum, accurately. After measuring the activity of a representative γ-emitter(Co-60, Cs-137), automatically, this assay system can be calculated total activity by utilizing scaling factor. Dividing a waste drum into 8 segments, vertically, and also 8 sectors in one segment to minimize the error, the specific activity of homogeneous and non-homogeneous waste drum can be determined by using matrix correction methods such as transmission ratio, differential peak absorption and mean waste density correction, individually or by combination. An optimum operating conditions of our system was induced by evaluating the affecting factors(drum's rotation speed, measuring time, source position and methods attenuation correction) on the measurement of activity. As a results, the measurement error was about 10% in a very low-level standard gamma source(Co-60; 93 μ Ci and Cs-137; 86 μ Ci) and was less than 30% in a very low-level standard gamma source (Co-60; 8.7 μCi and Cs-137; 9.3 μ Ci) located in the center of model drum (density; 1.1 g/cc)