Background: Environment gaseous radioactive iodine monitoring is important for nuclear power plant safety. 131I reference source is used as the measurement standard of reference response for environment gaseous radioactive iodine monitoring equipment

which uses glass fibrous filter

active carbon filter and impregnated activated carbon filter cartridge as carriers. Purpose: It is essential to calibrate the reference response for gaseous radioactive iodine monitoring equipment to ensure accurate gaseous radioactive iodine monitoring. Methods: Gaseous radioactive iodine was produced from Na131I solution with ferric sulfate through redox reaction

and collected under environment sampling condition for preparing the 131I reference source. The detection efficiency of high-purity germanium gamma spectrometer for 131I in collection device was determined. Therefore

the 131I reference source was prepared and quantified as a reference standard for field calibration. Results: The experimental results show that the activity of the 131I reference source will be about 10 kBq while the 1 MBq Na131I solution is prepared to get it

the radioactivity value could be adjusted by regulating the activity of the Na131I solution. The detection efficiency of gamma spectrometer for 131I reference source ranged from 4.90% to 6.82%

while the distribution parameter changed from 0.09 mm?1 to 0.34 mm?1. Conclusion: The preliminary experiment shows good practicability of proposed method for the calibration of reference response for gaseous radioactive iodine monitoring equipment. Abstract