Filtration of Radioactive Aerosols By Glass Fibers

The waste gases emitted from production and laboratory processes in the Hanford plants operated by the General Electric Company for the Atomic Energy Commission contain radioactive fission products which could result in the potentially hazardous contamination of the areas surrounding the plants if they were discharged directly to the atmosphere.(123) In accordance with the strict safety and health physics policies existing at the various AEC sites, considerable efforts have been expended to prevent any widespread contamination by either radioactive gases, such as I 131 , or by radioactive particulate matter suspended in the stack gases.(45) This paper represents the final report of an extensive program undertaken at the Hanford Atomic Products Operation to develop a means for the efficient removal of sub-micron particles from the contaminated gas streams.(6) The design specifications to be met in the filtration of radioactive aerosols are more rigorous than those of the ordinary commercial collector.Furthermore, since the collection of large amounts of contaminated material in one place is inherently dangerous, the stringent requirements of AEC safety policies restrict considerably the possible methods by which the air pollution problem may be solved.A brief summary of the specifications which were established as the development and design goals for the Hanford process air filters is presented in Table I.It is evident that the more common types of commercially available dust collectors, such as cyclones and scrubbers, fail to meet one or more of these specifications.An expedient solution to the problem of removing radioactive aerosols from the Hanford waste gases was a fixedbed filter consisting of successively finer gradations of sand, placed in a large underground container, and suit-(!) "Waste Disposal Symposium," Nucleonics, vol.4, No. 3, pps.9-23 (1949).( 2) "Ionizing Radiation Material as an Air Pollutant," Nucleonics, vol.6, No. 6, pps.70-71 (1950).< 3 ) Parker, H. M., "Review of the Stack Discharge Active Particle Contamination Problem," General Electric Co., Hanford Atomic Products Operation, Document No. HW-9259, (3-22-48).( 4 ) "Handbook on Aerosols."Atomic Energy Commission, Washington, D. C. (1950).< 5 ) "Handbook on Air Cleaning," Atomic Energy Commission, Washington, D. C. (1952).