11.

Do not process the 24 ball-milled samples collected at 1050 ft.
the 24 samples in soils library for possible future use.

Store

12.

(From Step 6 above).
Spread >10-mesh soil (collected at 150 ft) in the
shape of a circle on a clean plastic sheet.
Divide soil into 10 approximately equal pie-shaped parts using a clean straight edge.
Place each
part in a plastic bottle, record dry weight, and assign library numbers.
Rotate each bottle corner to corner for 5 sec.
Take a 10-g aliquot
from each bottle using plastic spoon.
Assign aliquot numbers.
Store

the soil remaining in the 10 bottles in soils library.

13.

14.

Count each of the 110 aliquots (100 are <10-mesh and 10 are >10-mesh) for
lam using Ge(Li) for 1000 minutes or until the percent count error
(2c) is 10% or less, whichever time is less.
Save samples in their present bottles for possible recounts or further analysis.

At a location well outside the radiation fallout pattern of NS-201 yet

within the same general soil type, collect 12 soil samples in the same
manner as was done in Step 1 above.
These samples will be used to pro-

vide radiation counter calibration. Dry and ball mill these samples as
in Steps 3 and 4 above used for radioactive samples. Sieve samples (no

weights required) through a 10-mesh screen combining the <10-mesh frac-

tion as one and the >10-mesh as another.

Mix each fraction separately

by kneading for 10 minutes. Withdraw aliquots of appropriate size from
the <10-mesh soil fraction and dose with standard solution used to
calibrate for gamma spectra as per discussion with Derek Engstrom.
Prepare dosed standards in same configuration (same bottle size and

style) as that to be used in counting samples.

It is suggested that

not less than 5 such standard aliquots of each size (1 g, 10 g, 25 g,
50 g, and 100 g) be prepared and used for estimating the calibration

curves.
15.

16.

Ten gram samples of the >10-mesh material collected in Step 14 above
are to be prepared as standards also as in Step 14 above.
Since the
sample will probably contain a wide range of soil particle sizes, a
large number of such standards should be prepared, perhaps 10.
A report giving the following information should be distributed to

Ms. Mary White (NAEG), Richard 0. Gilbert (Battelle-Northwest),

E. H. Essington (LASL), and to any other individuals designated by
Ms. White:

a)

241a concentrations (activity per gram dry weight), associated

aliquot numbers, aliquot weights, and bottle numbers (1 through 20).

b)

percent counting error (2c)

c)

Dry weight (grams) of <10-and >10-mesh soil fractions before the
samples were combined. Dry weights of soil in plastic bottles.

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