particle collection on each cascade impactor stage except for interstage
loss particles.
Particles were sampled at a flow rate of 0.57 m?/min
and those found on the stages were assumed to be without inertia with
respect to sampling efficiency.
Thus, small particles were assumed to
have followed the sampled air into the cascade particle impactor.
For
radiochemical analysis,
particles collected as interstage losses in the
impactors were combined with the large cowl particles.
After sample collection, the impactor* Type "A" fiberglass stage collectors were equilibrated with laboratory humidity (approximately 50%
relative humidity), weighed, and all stages and backup filter combined
into one "small" particle sample.
Particles collected within the cowl
and interstage loss particles were brushed off for collection, weighed,
and combined into one sample.
These "small" and "large" particle samples
were analyzed** for plutonium-239 and americium-241.
HORIZONTAL FLUX CALCULATION
Average horizontal airborne plutonium-239 and americium-241 fluxes were
calculated from the collected small and large particles.
Fluxes are in
units of pCi/(m@ day) for both large and small particles.
Two isokinetic
sampling assumptions were made for these calculations:
(1) for large
particles, particle inertia was assumed sufficient to cause particle
collection within the cowl inlet for all wind speeds; and (2) for small
particles, particles were assumed to be without inertia and followed
airflow.
For large particles, the flux was calculated from the uCi
collected in the cowl (plus interstage impactor loss) divided by the
product of cowl inlet cross-sectional area and sampling time.
For small
particles, the flux was calculated from the product of measured airborne
concentration per unit air volume sampled in the impactor, uCi/em3, and
average wind speed at each sampling height.
The average wind speed at
each height was: 1.6 m/sec at 1.9 m; 2.9 m/sec at 15 m; 3.4 m/sec at
30 m; 3.7 m/sec at 61m; 3.8 m/sec at 91 m; and 4.0 m/sec at 122 nm.
RESULTS AND DISCUSSION
Airborne plutonium~239 and americium-241 concentrations per unit air
volume, concentrations per gram of airborne solid, and horizontal fluxes
*Andersen 2000, Inc., Model 65-100 High-Volume Sampler Head, P.O. Box 20769,
AMF, Atlanta, Georgia 30302
*kLFE Environmental Laboratories, Richmond, California.
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