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CHAPTER 4

SAMPLE ANALYSES AND DATA REDUCTION
4-1

SAMPLE ANALYSIS

Besic analysis consistec of gamma ccuntineg thoce samples collected
for the determination of fallout contcurs ond measuring the falleut particle size distribution end the anrarent density of the rnarticles.

4.1.1

Counting Technique

Two instruments were emnloved in counting semnles. The 47 7amra
fonization chamber was used where conversion of measured activities to
gamma field intensities was desirec. The camme scinti}letion counter was
used where relative levels of activity were desired.
The 47 ramma fonization chamber and its calilration ere identicei
io that deserited in -ECD-2367,

This instrument consists of a pressurize?

ion chamber, vibrating reed electrometer, and a Brown millivolt recorder.

The chamrer is filled with arson st a pressure of 600 psig and onerstes
at a collection potential of 600 v. For low beckercund the assembly is
lead-shielded. Samples are lowered into the center of the chamter. Bectise the position of the source meterial is not. critical, activities of
larre volumes of either licuid or solic samples cer. be measured. The
gamma ionization chanter readings were converted arbitrarily from milli-

volts to mr/hr in order that all readircs taken on fallcut te excressed

on a conventional basis. A relaticnship between the chanher readings
in mv and a calibrated AN/PDR-T1B Survey meter was determined. Corresponeing readings of ‘5 randomly chosen sarvles from Shot 1 were taken by
both instruments. Tne eoustion of the resulting linear vlot showed

mr/or =

—0V__,

519

“

With this reletionship determined from ~arples of hich Jevels of activity

conversion of samnies of low activity, accurately messured in the 47
tonchanl er, readings coulc then be reliatly converted to equivalent
mr/hr.
The scintillation counter Veonsi sts of a detector assembly and
Li

Select target paragraph3