o14
HUFF
bility should occur under heavy fallout conditions, it could be a factor
of great importance.
For comparison purposes, the mean relative variability of 89Sr
and Sr rainout in five storms on the Boneyard and the Kaskaskia
networks and in five storms on the East Central Illinois network was
determined. Results are summarized in Table 4, in which five-storm
Table 4— MEAN RELATIVE VARIABILITY OF ®Sr AND "Sr
RAINOUT IN 1962 STORMS
Network
Boneyard— Kaskaskia
East Central
Illinois
15
20
88Sr, q
Concentration
Deposition
|
20
Sr, &
Concentration
Deposition
Storm rainfall, %
15
24
19
20
20
12
16
averages are shown. This table shows that, onthe average, the relative
variability of both the concentration and the deposition of *Sr and *Sr
was greater than storm-rainfall variability. Comparison of Tables 1
and 4 indicates that, in general, the relative variability of gross beta
is somewhat greater than that of sr and “Sr. Although the statistics
are based on a relatively small sample of storms and may be altered
as more data become available, the differences are in the expected
direction since the beta variability reflects the combined variability of
a large number of fission products.
Table 4 shows the expected trend
for the relative variability to be greater on the East Central Illinois
network of 400 square miles than on the small networks of 10 and
12 square miles.
POINT RAINFALL REPRESENTATIVENESS
Gross beta and strontium data collected on the Boneyard and the
Kaskaskia networks have been used in this study, which was confined
to convective storms. The radioactivity at a central gauge in each
network was compared with the average radioactivity determined from
all samples on the network. It was assumed that the network averages
represented accurate estimates of the true areal average, and the
central gauge differences were treated as sampling errors. Becauseof