- 12 :
241
tos
.
has been used to estimate the
Pu activity in other compartments.
The calculations have also been made using a ratio of 2414/239 ,240p,
of 3.0 which is slightly more than X + I¢(i.e., 1.85 + 1.0 = 2.85).
b.
Lagoon surface water has an average
239, 240 Pu
concentration of
39 £Ci/1 (Ref. 2, Ref. 1). Using a ratio of 1.85 7#4py/239>?40,
the 241bu activity is 72 £Ci/1l.
The ratio of 24d to 239,240,
is 0.11 (Ref. 3); therefore, the 241am activity is 4.3 f£Ci/1.
The maximum 241 Am activity which will result from decay of present
levels of 24d is 72 (0.026) = 1.87 fCi/l.
over present 241any activity.
The total
241
This is a 43% increase
Am which will result
ts 6.2 £Ci/l which is 16% of the 799>74%pu activity.
Plankton
Concentrations in pCi per gram wet weight of
241 Am and 239, 2405,
in plankton samples are 0.23 and 0,39 respectively (Ref. 1).
Using
the factor 1.85 for 241/739 22405, the a concentration would be
0.72 pCi/g. Maximum growth from this level of 7*!pu will be 0.72
this
Relative to the present 2a dA level of 0.23 pCi/g
represents an 8% increase.
0.249 pCi/g.
Relative to the
The total 24.am is 0.23 + 0.019
239,240
or 64%.
Pu levels this is 0.249/0.39
Ml
(0.026) = 0.019 pCi/g.
0.64
~
However, a more realistic situation is that the plankton will always
reflect the same ratio of
water concentrations,
241 Am
to
239 ,240 Pu
as they do to the present
Therefore, the increased 241an water concentrations
resulting from the “grow in" from 241nu will lead to 24]a concentrations
in plankton which are 85% of the
239 , 240 Pu
concentrations.