The penetration of aerosols through fine orifices

A practical procedure has not been developed and accepted internationally to quantify the leakage of aerosols in tests of radioactive transport flasks. Hence it is necessary to understand and quantify aerosol penetration through model pathways that have leakage rates close to the limits set by standards of flask integrity. The penetration of particles from 0.5 to 15 μm volume equivalent diameter has been measured through critical orifices in the range from 2 to 100 μm at thickness ranging from 12.7 to 509 μm. The present study is a limiting case where a capillary is reduced in length until it becomes an orifice. In reality, leaks across seals will normally take the form of short capillaries. A common correlation has been found in the variation between air leakage rate and particle penetration for both capillaries and orifices, and this relationship has enabled mass-based particle penetration rates to be estimated. (author)