212 TRANSURANIC ELEMENTS IN THE ENVIRONMENT 



TABLE 10 Calculated Airborne Concentrations from Airborne Solids Concentrations 



and Surface Contamination 



where 



'^'Pu: MPC.ohr = 2 x 10"' ' MCi/cm' 

 MPC, ,,hr = 6 X 10-" MCi/cm^ 



" ■' Cs: MPC, hr = 6 X 1 0-" MCi/cm' 

 MPC,,,hr = 2 X 10-' nGlcm^ 



Mass loadings in these respirable and nonrespirable ranges are shown as upper limits of 

 0.7 mg/m^ for respirable particles and 231.8 mg/m^ for nonrespirable particles. The 

 lower limits are 7.7 jug/m^ for respirable particles and 20 mg/m^ for nonrespirable 

 particles. These mass loadings were multiplied by maximum surface contamination levels 

 for ^^^Pu and *^^Cs as shown in Table 3. This approach yielded a predicted maximum 

 airborne ^^^Pu concentration for respirable particles of 4.92 x 10^'^ jiQ\lcm^ and a 

 predicted lower limit of 5 .33 X 10"'^ AtCi/cm"' . 



Upper and lower limits of '^^Cs concentrations on respirable and nonrespirable 

 particles were calculated similarly. However, a comparison of airborne ^^^Cs and ^^^Pu 

 concentrations predicted by this method and measured airborne concentrations shows the 

 shortcomings of this calculational approach. The predicted respirable range of ^^^Pu 

 concentrations from 5.33 x 10"^^ to 4.92 X 10~'^ )uCi/cm^ is within the lower two 

 orders of magnitude of die 10~^^ to 10"''* )uCi/cm^ experimental range shown in 

 Fig. 7. This simUarity in range is considered fortuitous when one also compares the 

 predicted '^"^Cs respirable range from 1.93 x 10"'^ to 1.78 x 10"' ' juCi/cm^ with the 

 experimental range from 2 x 10"'^ to 3 x 10"'^ /iCi/cm^ (Sehmel, 1977c). For '^^Cs 

 the minimum predicted airborne concentration of 1.93 x 10 '^ /jCi/cm^ is 0.6 of the 

 maximum experimental concentration of 3 x 10 '^ ^tCi/cm^. However, the maximum 

 predicted airborne concentration for '^''Cs of 1.78 x 10'' /.(Ci/cm^ is 60 times the 

 maximum experimental concentration of 3 x 10"'^ /iCi/cm^. These ratio comparisons 



