Development of Submicron Particle Size Classification and Collection Techniques for Nuclear Facility off-Gas Streams

摘要

High efficiency particulate air (HEPA) filters are an essential part of nuclear facility off-gas cleanup systems. However, HEPA-rated sampling filters are not the most appropriate samplers for the particle penetrating off-gas cleanup systems. Previous work at the Idaho Chemical Processing Plant (ICPP) estimated perhaps 5% of the radioactivity that challenged sampling filters penetrated them in the form of submicron particles - typically less than 0.2 microns. Accordingly, to evaluate these penetrating aerosols more fully, a suitable robust monitoring system for size differentiation and measurement of submicron particles was developed. A literature survey revealed that the diffusion battery was the best choice for particle size classification and that the electrofluidized bed was the best method for particle collection in ICPP off-gas streams. This report describes the laboratory study and in-plant demonstration of these two techniques. (ERA citation 06:015367)