High efficiency mixed species radioiodine air sampling, readout, and dose assessment system

Accidental releases of radioactivity from fission reactors will consist of active vapors or aerosols. Composition of the released plume will depend on the energy of release and fission product volatility. An apparatus is described that can efficiently (95 percent) collect organic or inorganic, particulate or gaseous 131I in the usual concentration range including that below stable atmospheric iodine, and under severe ambient conditions. Response to noble fission gases was reduced to less than 10-4 of an equal iodine airborne activity by heating the collector to approximately 1200C in clean purging air flowing at .14 m3/min for 11 min. Reliable sample size, +-5 percent, was achieved by using a sample air flow regulator. Thyroid dose commitment was mathematically and graphically related to the iodine isotope distribution expected in the environment and to the response of the Civil Defense CDV-700 instrument used to evaluate the sample. Sensitivity of the method allows dose assessment of 1-2 rads to a child's thyroid