Evaluation of decontamination factor of radioactive methyl iodide on activated carbons at high humid conditions

Radioactive iodine (131I) released from nuclear power plants has been a critical environmental concern for workers. The effective trapping of radioactive iodine isotopes from the off-gas stream generated from nuclear facilities is an important issue in radioactive waste treatment systems evaluation. Numerous studies on retaining methyl iodide (CH3I131) by impregnated activated carbons under the high content of moisture have been extensively studied so far. But there have been no good results on how to remove methyl iodide at high humid conditions up to now. A new challenge is to introduce other promising impregnating chemical agents that are able to uptake enough radioactive methyl iodide under high humid conditions. In order to develop a good removal efficiency to control radioiodine gas generated from a high humid process, activated carbons (ACs) impregnated with triethylene diamine (TEDA) and qinuclidine (QUID) were prepared. In addition, the removal efficiencies of the activated carbons (ACs) under humid conditions up to 95% RH were evaluated by applying the standard method specified in ASTM-D3808. Quinuclidine impregnated activated carbon showed a much higher decontamination factor above 1,000, which is enough to meet the regulation index for the iodine filters in nuclear power plants (NPPs). (c) 2020 Korean Nuclear Society, Published by Elsevier Korea LLC. All rights reserved. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This study focuses on effectively removing radioactive iodine released from nuclear power plants under high humidity conditions. The use of impregnated activated carbons to capture radioactive methyl iodide and the introduction of new chemical agents to enhance removal efficiency were explored. Results showed that quinuclidine impregnated activated carbon exhibited a higher decontamination factor under high humid conditions.