Plutonium Biokinetics in Human Body A. Luciani - Kit-Bibliothek - FZK

Daily urinary excretion [Bqd -1 ]
1E+0
1E-1
1E-2
1E-3
1E-4
Measurements for 239Pu+240Pu
239 Pu+ 240 Pu
Model predictions for 239Pu+240Pu
239 Pu+ 240 Pu
Measurements for 238Pu
238 Pu
Model predictions for 238Pu
238 Pu
1 10 100 1000 10000 100000
Days post intake
Figure 3.2.6 Measurements and model predictions for Americium activity excreted in urine
for the Scenario 3 of contamination (see Table 3.2.1).
Model’s predictions for the urinary excretion of Plutonium were also evaluated for the
same previous scenarios. The intakes calculated on the basis of the Americium activity
retained in the lungs were multiplied by the model’s predictions for the urinary excretion per
unit of intake (e u(t)). The resulting values are presented with the available measurements for
comparison purposes in Figure 3.2.4, Figure 3.2.5 and Figure 3.2.6 for the scenarios of
contamination number 1, 2 and 3, respectively (Table 3.2.1).
Model’s predictions for Americium in the lungs and the urinary excretion of
Plutonium clearly point out that the basic assumption characterizing the scenario 2 of the
contamination (absorption type M for Plutonium) is not realistic. The predicted Americium
retention in lungs considerably underestimates the experimental data already after 100 days
post intake (Figure 3.2.2). Furthermore the intake evaluated from Americium lung retention
data at short time (for which model’s predictions are still good) determine a model’s urinary
excretion of Plutonium in disagreement with the relating experimental findings (Figure 3.2.5).
Therefore such scenario of contamination was not considered anymore and all the attention
was then focalised on the scenarios 1 and 3.
From the plots relating to the Americium burden in the lungs it can be pointed out that
the retained activity at short time (up to about 100 days post intake) is mainly due to directly
inhaled Americium. On the contrary, at long time, the activity in lungs is mainly due to the
Americium ingrowth from 241 Pu decay. For both the scenarios 1 and 3 model’s predictions for
the Americium lung retention at short time and the urinary excretion of Plutonium up to 2,000
days post intake fit the experimental findings. Therefore the assumptions on the absorption
type for the Plutonium (type S) and for the Americium directly inhaled (type M), common to
both scenarios, seems to be appropriate. It should be pointed out that only the Plutonium
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