quant TIT. Wy) TECHNICAL COMMAND REPORTS. (TCR) TR - 60 - INTERIM REPORT OF THE DEVELOPMENT OF THE RADIOACTIVE SODIUM IODIDE TEST FOR FILTER MATERIAL. - Elmer H. Engquist and Jerry J. Mahoney, 18 April 1950. SECRET i The development of a test method for the determination of type 6 filter material efficiency is described, the method employing particulate sodium iodide labeled with 131, An serosol having a mean particle size of 0.48: was used to test the efficiency of Chemical Corps type 6 filter material at levels of radioactivity between 0.1 and 20.0 uc/l (0.6 Mev beta energy and 0.37 Mev gamma energy). The filter material exhibited normal filtration efficiency (approximately 0.03% to 0.04% penetration) up to the highest of these levels. The accuracy of these measurements by radiometric methods, checked by nonradioactive chemical tests was found to be within + 10%.