Cook Plant preoperational studies 1970 / John C. Ayers ... [et al.].

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The parallel passes made at the Palisades and Cook Plants permitted interpolations to be made for gross gamma activity between the passes. Contour lines
drawn between the passes show the areas of particular radiological interest.
Gross gamma activity is recorded on a strip chart recorder throughout a
survey. Figure 4 shows the contour lines drawn between the passes made near the
Donald C. Cook Plant. Ridges of relatively high gross gamma activity can be seen
near the shoreline about two miles north and about two miles south of the
plant. An area of relatively low activity can be seen about two miles off
shore from the plant.
The only radionuclides present in the gamma ray spectra taken near the
Palisades and Cook Plants were naturally occurring potassium-40 and radium-226.
Figure 5 is an attempt to construct contour lines of pctassium-40 in the
sediments near the Donald C. Cook Plant. The same areas of relatively high and
low activities observed in Figure 4 are apparent in Figure 5.
CONCLUSIONS
An underwater gamma radiation probe was constructed to provide qualitative
and quantitative measurements while traveling over bottom sediments. The underwater probe was used at two nuclear power plant sites to determine preoperational
levels of radioactivity present in the sediments near the plants. Contour
lines of gross gamma activity and the naturally occurring radionuclide potassium40 were drawn to identify areas of relatively high and low activities.