5
Yate
*
>CRRien
completely unknown. (3) Complicated wind structure blew debris below 10,000 feet and above
tropopause to the west, intervening debris to the east.
Comparisons have been made between total debris production and total fallout as estimated
from test site survey data and world-wide gummed paper collections. The gummed paperis
here assumed to have an efficiency of 100%, although probably it is less than 50%.
For the
Nevadaseries of the spring, 1953, where approximately half of the debris was produced in tower
shots and half in air drops, the following debris inventory through June 14, 1953, has been
estimated: 4
Within 200 miles of test site.......................
U.S. (excluding 200 mile circle)............ .......
Northern Hemisphere (excluding U.S.).............
Southern Hemisphere .......................-....
World total fallout..........0....00.000.0......4..
9% of debris produced
3
Do.
12
1
25%
Do.
Do.
Do.
For the Pacific tests of November 1952, observed world-wide fallout ® was only a few percent
of debris produced. However, data from the spring, 1954, tests make it apparent that a large
fraction must have fallen out unobserved within a few hundred miles of the test site in the
case of the high yield surface shot.
,
3. Soil analysis for Sr-90:
The analysis of Sr-90 concentrations in soil is being carried out in Project SUNSHINE.
Libby * has measured approximately 500 dpm/ft? of Sr-90 for 7 alfalfa fields in the Chicago
area, as of September 1953. A somewhat higher value may be obtained when further measure-
ments on fused rather than HCL-leachedsoil samples are completed.
A single soil sample from
Ankara, Turkey, showed about 250 dpm/ft? Sr-90. Harley has found activities of about 0.5 yc
Sr-90/ft ? on the most highly contaminated Pacific islands following the test of March 1, 1954.
Additional analyses of foreign soil samples will soon be available.
Libby’s Chicago data were approximately 5 times higher than predicted from the gummed
paper data for the region (assuming no fractionation of the isotopes in the gummed paper
collections). This may indicate that the gummed paper efficiency is only 20%. However,
Harley’s }? analyses of Sr-89 and Sr-90 activity in 3 pastures in New York and New Jersey, one
in Georgia, and one in Utah, gave ratios of measured to predicted values of only one or two.
D. Behavior of fission products in physical environment:
1. Air:
The behavior of weapon debris in the air has been covered in Section B above, dealing with
meteorology, rainout, and atmospheric storage.
2. Water:
H. A. Thomas of Harvard University has carried out extensive measurements on contamination of rivers and reservoirs by fallout in the Boston area. Approximately 0.8% of the activity
which falls out in that region has been found within weeks in the streams. Since 2% of the
watershed is covered by water, Thomas has concluded that only the activity which falls on a
water surface finds its way into the water system. His measurements do not exclude the possibility of slow leaching over a long period of time.
W. F. Libby * has analyzed during 1953 the Sr-90 content of the following rivers: Mississippi,
Mosel, Seine, and Donav (near Ulm, Germany). The average activity -was 0.4 dpm Sr-90 per
gallon (range 0-1.1 dpm/gal), or less than that of rainfall by a very rough factor of 10.
Thomashas studied the effect of standard water purification procedures on the gross fallout
content of reservoir water. Alum flocculation plus rapid sand filtration reduced the activity
Footnote references on pp. 42-43.
__
9