PLUTONIUM-BEARING PARTICLES FROM FUEL REPROCESSING 129 



TABLE 8 (Continued) 



Fraction with diameter < D 



Diameter System Sampling Sampling Sampling Sampling Natural 

 (D), Mm I point A point B point C point D aerosol 



0.972 

 0.986 



1.000 



*The percent ot the positive analyses less than, within, and greater than 

 one geometric standard deviation of the global geometric mean enrichment 

 factor. 



diameters (in micrometers); and, in columns 2, 3, 4, 5, and 6, the fraction of the particles 

 having diameters equal to or less than each diameter measured in System I and sampling 

 points A, B, C, and D in System II, respectively. These fractions are also plotted on the 

 logarithmic probability graph given in Fig. 7. 



For comparison a cumulative frequency plot was also made of the size distribution of 

 particles in natural atmospheric aerosols. A very simple function that has been used 

 extensively in atmospheric research to express particle size distribution in both natural 

 and polluted atmospheres is 



dU 



where N is the number concentration or total number of particles per unit volume having 

 diameters from the lower limit of definition of aerosols up to diameter D (in 

 micrometers). From the relationships 



dD=Dd(lnD) (2) 



and 



In D= In lOlouD (3) 



