[en] Iodine penetration and ignition temperature data obtained from carbon that was removed from the Savannah River Plant (SRP) confinement system show that Type GX-176 carbon has a useful life of at least 30 months. Development studies on new halogen adsorbers showed that coal- and petroleum-base carbons can be treated in the laboratory to retain methyl iodide as well as, or better than, commercial coconut-base carbons. Radiation stability tests for iodine-loaded, silver-exchanged zeolite (AgX) showed that some internal migration of iodine occurs in the AgX under dynamic flow conditions in a high intensity radiation environment. The tests also showed that the distribution of iodine in the test bed is more affected by the inlet air concentration than by exposure to gamma radiation