Removal of gaseous radioiodine with solid adsorbents

In nuclear power plants only activated impregnated carbon is used to remove airborne radioiodine from exhaust air and off-gas. In reprocessing plants mostly wet washing processes are used for iodine removal. As solid iodine adsorbents, only silver containing materials have been qualified for cleaning the reprocessing off-gases which are poisoned with NOsub(x). Iodine filters with impregnated activated carbon can be designed for removal efficiencies of 99.99% for elemental iodine and 99% for methyl iodide (a typical airborne organic iodine compound) under the most unfavorable operational conditions. From the operational experience it can be concluded that a high bed depth (for example 20-50 cm) together with a residence time of about 1 s will ensure a high performance (>= 99% for CH3131I) and a reasonable time of operation (approx.= 1 a) of a well designed iodine filter with impregnated activated carbon as the adsorbent