we
geiger counters.
~g-
The activity measurenent and the weether date for
each sample are entered on IBM cards for calculation. and tabuletion.
The results of this work have been presented in several summary papers.
The gummed film has two major disadventages.
First, it does not
allow direct measurement of Sr-90 fallout, end second, from two standpoints it is not e perfect collector of fellout.
There are definite
indications that there is sone wash-off of redioactive materiel during
precipitation.
Khen there is no precipitation the gummed film may
collect more activity than would be found on.a square foat of a perfect
collector since same airborne dust, which would nat settle ordinarily,
may be scavenged by the gummed surfece.
Experiments in several locations,
however, have shown an average collection efficiency of ebout 60% and
this value is used to correct the measured values obteined in the
laboratory.
This will be discussed further in a.later section.
The edvantage of gumed film. is its extreme simplicity es a
collector end its adaptability to network operation with a central
processing facility.
In addition, the fect that the gmmed film can
be measured on a daily besis offers some edventage in detecting the
time of errival of radioactive meteriel.
This is particulerly useful
in the estimation of the law levels of total gamme dose essaciated with
fallout, since the gemma dose at any given location is sensitive to the
time of errival of the fission products.
|
Atmospheric Sempling
The fission products, including Sr-90, ere in perticulate form in
the etmosphere and the most common eir sacpling procedure is to draw
e lerge volume of eir through e filter.
The dust on the filgter can
then be analyzed for Sr-90 and the atmospheric concentration cen be
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