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|  DOE-HDBK-3010-94
4.0 Solids; Powders
20
18
16
14
12
10
8
6
4
2
0
2
4
6
8
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20
Wind Speed, mph
Figure 4-20. Percent of Soil Airborne as a Function of Wind Speed
(Figure 6 - Sutter August 1980)
suspension. Powders at rest are difficult to deagglomerate and disperse often requiring
substantial mixing in suspensions to attain their original size distribution.
4.4.3.3.1
Vibration Shock
No study directly applicable to this phenomenon was found. It appears that the value for
ARF should exceed that for resuspension alone (see section 4.4.4) but be less than for a free-
fall spill of powder (ARF and RF of 2E-3 and 0.3 in subsection 4.4.3.1.2). The powder
undergoing vibration shock (e. g., seismic vibration) is bounced into the air while subject to
the same airspeeds as would impact the material for aerodynamic entrainment. The effect is
less than free-fall of the same powder as it is not subject to the same intensity of phenomena.
Based on experience and judgement, Mishima, Schwendiman and Ayer (October 1978)
selected a bounding ARF and RF of lE-3 and 1.0 for the suspension of powder-like surface
contamination by shock-vibration. The experiments performed by Langer (1987) discussed
in Subsection 4.4.3.3.2 below involving the suspension into flowing air of powders on
plywood by impact of large pieces of debris also indicated a maximum ARF value of lE-3.
Particles comprising surface contamination are assumed to be more widely dispersed and not
as agglomerated as "thick" layers of particles that represent powders. Figure A.41 indicates
the forces necessary to deagglomerate/disperse powders. Therefore, for clumps/piles of
Page 4-84
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