[en] Non-destructive assay is effective for management and disposal of transuranium (TRU)-contaminated wastes. Several measurement techniques have been developed such as: (a) Passive γ-ray technique; TRU nuclides emit specific γ-ray. TRU content could be analyzed by γ-ray energy spectroscopy. (b) Passive neutron technique; Alpha-particle emitted from TRU reacts with light elements and generates neutron. Some TRU also generate spontaneous fission neutrons. TRU content could be evaluated by the neutron counting. (c) Active neutron technique; Some TRU are fissionable and generate fission neutrons when exposed to an external neutron source. The TRU content could be evaluated by the fission neutron counting. An active neutron technique which is expected to be highly responsive has been tested in Mitsubishi to measure the TRU content in 200-liter waste drum. The apparatus consists of graphite assay chamber, pulsed-neutron generator, He-3 neutron counters and data acquisition system. The drum is irradiated by periodical neutron burst. The fast neutrons generated from the TRU are counted during the bursts. The counts would be proportional to the TRU content. The results for various waste drums show marked dependency of neutron response on the composition of the waste matrices. The detectable limit is about 2 mg of the fissile TRU for low density matrix and about 20 mg for high density matrix. The limit could be improved by increasing the counters and attainable to about 10 mg of the fissile TRU for high density matrix. However, the active neutron technique is applicable only to fissile TRU and is affected also by the waste matrices. Total TRU content could be evaluated by a combination of informations on TRU isotopic composition and waste matrix properties. (author)