244 TRANSURANIC ELEMENTS IN THE ENVIRONMENT 



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I 





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DC 

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Impactor operation 

 O Continuous, all winds 

 A 4.1- to 6.3-m/sec winds 

 D 6.3- to 9.8-m/sec winds 



J I I I I ml \ I I I I I III \ I II 1 1 III \ L 



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10-18 10^17 10-16 10-15 10-14 



AIRBORNE 233pu CONCENTRATION, AiCi/cm^ (FROM TOTAL IMPACTOR SAMPLE) 



Fig. 6 Total airborne ^^'Pu concentration at AB site at Rocky Rats as a function of 

 wind speed. 



concentration at the 1-m height of site AB is one to two orders of magnitude greater than 

 at otlier heights for this site. More important to the hot particle concept is the 

 concentration at the 10-m height of site B. This concentration of 2.3 X 10^'^ juCi/cm^ 

 was the largest ^^^Pu concentration for 2-)um particles measured at any Rocky Flats 

 location. This relatively high concentration was unexpected since this sampling location 

 was the most remote from both the ground and the original oil storage area. This suggests 

 that other relatively hot particles could also be escaping from the plant boundaries; 

 however, due caution is indicated in interpreting this hot particle concept. The total of 

 6 d/min collected on the 2-jum stage, or 2.3 x 10^'^ /uCi/cm^ , is much less than the MPC 

 in air of 2 X 10"'^ juCi/cm^ (occupational). It is conceivable that the majority of this 

 hot plutonium was attached to one soil particle. 



The functional relationship between airborne plutonium resuspension concentrations 

 and wind speed could not be developed as unequivocally as initially anticipated (Sehmel 

 and Uoyd, 1976b). This was due in part to the inadvertent loss of about a fifth of the 

 collected filter samples during radiochemical analysis. Unfortunately, most samples from 

 the higher wind speeds were lost. Even with the Umited plutonium data collected in this 

 experiment, it was evident that airborne ^'^^Pu concentrations increased with an increase 

 in wind speed. In Fig. 6 total airborne concentrations are shown for air sampled at all 

 wind speeds (average wind speed of 0.9 m/sec), at wind speeds from 4.1 to 6.3 m/sec, and 

 at wind speeds from 6.3 to 9.8 m/sec. Airborne ^^^Pu concentrations at wind speeds 

 from 4.1 to 6.3 m/sec are definitely larger than average airborne concentrations for 

 continuous air sampling. However, the 2a radiochemical counting statistics error limits 

 are too large to determine the wind-speed dependency. Nevertheless, an attempt to 

 approximate airborne ^^^Pu concentrations and consequently the resuspension-rate 



