Cook Plant preoperational studies, 1969 / John C. Ayers ... [et al.].

minutes in The Beckman Low-Background Beta Counter. The average gamma detection
efficiency for the 5 inch NaI(T1) crystal and multichannel analyser combination
is 20% over the energy range of 0.02 to 2.0 million electron volts. This value
was used to calculate the gross gamma radioactivity as indicated by the 200
minute count. The efficiency of the low-background beta counter was 42% for
gross beta counting. Gross gamma and beta radioactivity was calculated and
recorded as picocuries per gram (pCi/gram) of amphipod (see table #1).
RESULTS
Gross beta radioactivity in the amphipods ranged from 0.55 to 10.93 pCi/gram.
The range of gross gamma radioactivity in the amphipods was 4.07 to 40.20 pCi/gram.
When gross beta and gamma activities were plotted on a scaled map of the study
area the patterns of radioactivity shown in figures /l1 and Yk2 were drawn.
CONCLUSIONS
The patterns of both types of radioactivity reveal the infl,:ince of the
nuclear power plant on levels of environmental radioactivity. Water from an area
near the discharge channel of the power plant was previously assaved and contained 54 pCi per liter, gross gamma activity. Gross gamma activity in P. affinis
used in this experiment apparently exceeds the concentration in the water tested
by from 76 to 745 times. More water samples from the study area are being
analysed for gross radioactivity. The results of these tests will be comparec
with levels of radioactivity reported for the study area prior to plant operation.

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