In order to determine quickly and conveniently several man-made radionuclides of low-level specific radioactivity in batch of powder samples

the γ spectrometry non-destructive analysis is adopted.Each sample about 1 g in weight was loaded into a custom-made plastic box

forming a small disk of Φ26 mm×3 mm.Sample boxes were measured in the lower position

about 1 cm from the HPGe detector(referred as Position H1).Without the same solid standard source for efficiency calibration

so some planar sources(in same diameter) containing many radionuclides were calibrated by standard 60Co planar source in position H25

25 cm from the detector.Then peak efficiencies for planar sources on H1 were obtained.By increasing distance 1 mm each time around position H1

planar sources were measured.Fitting the efficiency vs.distance curve

the efficiencies for disk source with thickness of 3 mm were calculated.Finally specific activities were evaluated including self-absorption correction.The differences of results between this method and radiochemical analysis are no more than 4% by just comparing two nuclides of some samples.