Investigations on the Testing of Iodine Filters by Different Methods

The retention of ¹³¹ I by a deep bed carbon filter (adsorber) of an FRG pressurized water reactor under normal conditions was determined with different test methods. These comprised (a) in-place tests on the carbon filter with CH₃^I3II and ¹³¹ I from the plant (contained in the exhaust air) and (b) laboratory tests on carbon samples with CH₃¹³¹I. The laboratory tests with CH₃¹³¹I produced results that were not conservative with respect to the organic ¹³¹I from the plant because of the occurrence of more penetrating organic ¹³¹I species in small proportions (<10%).