TRANSURANIC AND TRACER SIMULANT RES USPENSION 24 1 



L 



HIGH-VOLUME SAMPLER 



SYSTEM 

 SUPPORT 



ARM 



WIND- 



CYLINDRICAL 

 SAMPLE INLET 



'}>~~^£-—^^aU CASCADE IMPACTOR 



CYLINDRICAL 

 COWL BODY 



•SPINDLE EXTENSION 



WIND-ORIENTATION 

 TAIL FIN 



SPINDLE BEARING 

 ASSEMBLY BOLT 



WIND- 

 DIRECTION 

 SENSITIVE 

 ROTATING 

 COWL 



Fig. 3 Rotating cowl and impactor. 



Plutonium Resuspension Research at Rocky Flats. Plutonium resuspension at Rocky 

 Flats was investigated experimentally (Sehmel, 1976a; Sehmel and Lloyd, 1976b). In 

 early work an empirical resuspension model was developed (Sehmel and Orgill, 1973) 

 which was based on published weekly plutonium concentrations at Health and Safety 

 Laboratory sampling station S-8 along the site's eastern security fence. The plutonium 

 data were analyzed in terms of the meteorology during sampling times. Collected airborne 

 plutonium was related to hourly average wind speeds and wind directions. Model results 

 showed that airborne plutonium concentrations increased as the 2.1 power of wind speed. 

 Subsequently airborne concentrations were predicted for the succeeding time period. 

 These results showed a wide difference between predictions and experimental results. The 

 interpretation of these differences was that the plutonium resuspension source charac- 

 teristics had changed (Sehmel and Orgill, 1974). 



Battelle— Northwest experimental measurements of plutonium resuspension at Rocky 

 Flats were made in July 1973 (Sehmel, 1976a; Sehmel and Lloyd, 1976b). As shown in 

 Fig. 2, airborne plutonium concentrations were measured at three sampling sites east of 

 the plant. The first sampling site was along the eastern security fence. This site was called 

 sampling site A. Sampling site B was along the eastern cattle fence, and sampling site AB 

 was between sites A and B. The distance from site A to site AB was 227 m. Airborne 

 plutonium at these sites was sampled and analyzed as a function of sampling height, 

 particle size, and wind speed. For comparison, a particle cascade impactor sample was 

 simultaneously collected at a background site 13 km west in the mountains. 



