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HW -80991
and for measuring radionuclides that have reached the ground water.
Virtu-
ally all of the radionuclides present in the ground water have been introduced
with liquids sent to the cribs.
The quantity of radioactive materials sent to ground during 1963
(excluding tritium and the materials sent to the storage tanks) was about
36,000 curies.
This did not significantly change the historical total which is
estimated to be 2.6 x 10° curies.
Because of radioactive decay, the current
total in the ground is estimated as 2.6 x 10° curies.
the bulk of this material is Rul?®, cs!9" ,
andSr
90.
In order of abundance,
Figure 19.shows the
probable extent and concentration of radioactive materials (excluding tritium)
in the ground water.
(11)
The detectable beta contamination (not including tritium) in the ground
water beneath the 200-W Area was less extensive in 1963 than in previous
years.
This resulted because of a reduction in the amount of contaminants
discharged to ground, radioactive decay, and further dilution in the ground
water.
A substantial amount of tritium has been sent to the ground with the
intermediate level liquid wastes from the separations plants.
Figure 20 shows
the probable extent and concentration of tritium in the ground water in
December, 1963.11) In all probability some tritium and Ru 106
originating at
the chemical processing areas is now entering the Columbia River.
However,
the contribution of these nuclides is too small to be detectable in the river
water and any exposure from them is negligible.
HI.
RADIATION EXPOSURE
The total radiation dose that is received from environmental sources
differs substantially between individuals because their food and beverages
come from various supplies, because the kinds and quantities consumed are
subject to individual preference, because some people do more swimming,
fishing, and boating than others, and because of other personal habits.
These
inherent variations between individuals require a somewhat subjective approach to the question of probable total exposure in relation to various limits.