Chemical Forms of Airborne Radioiodine in the Exhaust Air from Iodine-131 Production Plant

Abstract

Airborne radioiodine released from the reaction cell into the exhaust air during the processing operations at an ¹³¹I production plant has been analyzed by radio-gaschromatography. The iodine compounds observed were CH₃ ¹³¹I, C₂H₅ ¹³¹I, H¹³¹IO₄ and H¹³¹IO₃. The distribution of the total ¹³¹I among these compounds differs greatly according to the time of sampling after the start of processing. In the beginning, H¹³¹IO₃ is highly predominant, but the content of organic iodides increases with progress of the processing operation. The removal efficiency of the charcoal filter installed in the stream of the exhaust air was better than 85% for the total ¹³¹1 but less than 50% when organic iodides alone were taken into account, indicating poorer efficiency of the filters for the latter compounds. The total amount of CH₃ ¹³¹I released was of Mc1 order. This suggests a very promising new method for obtaining CH₃ ¹³¹I as a by-product without any special chemical treatment.