Abstract: In order to carry out the traceability and transmission of the value of radioactive environmental monitoring instruments, according to the characteristics and generation methods of X and γ reference radiation in GB/T 12162.1—2000 and the calibration specification of JJF 1733—2018, the environmental level multi-source γ-ray kerma standard device was established. The experimental results show that: the air kerma rate range of the standard equipment for multi-source γ-ray air kerma at environmental level is (1.0×10^-1-3×10²) μGy/h; the radiation field with non-uniformity of less than 5% at 1 m is ø 300 mm; and the inverse square law is consistent within 5.0% in the range of 1 m-5 m from radioactive source. The stability and reproducibility of the device measured by standard ionization chamber were 1.7% and 0.5%. The relative extended uncertainty of the device is 3.0% (k=2) by evaluating the uncertainty component of the measurement results. The measurement results show that the performance indicators of the environmental level multi-source γ-ray air kerma standard device meet the requirements of the calibration of the environmental level dose measurement instrument.

Key words: gamma rays, environmental monitoring, kerma, standard equipment