Methods of Estimating Intake cont'd - doe-std-1128-98_ch10141

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DOE-STD-1128-98
Tables 5.6 for class W and Y forms of 239Pu. These functions would be similar in
value to those for other long-lived forms isotopes of Pu.
Qt =
Intake * IRF(Q t )
(5.6)
In its simplest form, a compartment content at any time post-intake (Qt) can be
expressed as the product of intake multiplied by the intake retention function value
for compartment Q at time t post-intake, or:
Results predicted by the model can then be compared with the observed bioassay
data. Such results are often referred to as expectation values.
Simple algebraic manipulation of the model allows calculation of intake from the
compartment content at time t, as shown below:
Intake =
Qt
.
IRF (Q t )
(5.7)
When multiple data points are available for a compartment, the intake can be
estimated using an unweighted or weighted least-squares fitting procedure, as
described by Skrable et al. (1994b) and Strenge et al. (1992) or as can be found in
most statistics textbooks. As an alternative, data can be fit by eye to a graphical plot;
however, the apparent fit can be misleading if data has been logarithmically
transformed.
Intake can also be estimated from air sample data, as described in Section 5.7.4. This
method is appropriate if bioassay data are not available or insufficiently sensitive.
Intake estimates based on air samples and bioassay data are also appropriate as a
check on each other. Valid bioassay data showing detectable results should be given
preference over intake estimates based on air sample results.
5-31

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