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

2.4.2.2 Performances
The energy calibration of the alpha detectors was carried out using standard sources
containing 233 U, 239 Pu, 241 Am and 244 Cm. The FWHM of the detectors used in the laboratory is
about 17 keV for 241 Am (energy resolution about 0.3 %). In the practical situations the FWHM
and therefore the energy resolution depend on the thickness of the deposit on the planchet: 30-
35 keV may be considered as an indicative value of FWHM for most of the actual
measurement conditions [151].
At the present the routine measurements performed at the FZK Toxicological
Laboratory are not able to discriminate 239 Pu from 240 Pu. Thus, efficiency factors and,
consequently, activity measurements on such radioisotopes relate to the sum of their
contributions.
Efficiency calibration is normally carried out using standard sources of 241 Am of 523
Bq activity certified at 14.7.1989.
The FZK Toxicological Laboratory provides a value of 5•10 -4 Bq for the MDA for
each radionuclide. The value refers to the whole bioassay laboratory equipped with numerous
alpha spectrometric chains: therefore it can be considered as an indication of the general
performances of the laboratory.
2.4.2.3 Measurements execution
A blood sample was taken from the subject in the period of staying in the
Forschungszentrum Karlsruhe. Three urine and feces samples were collected by the subject
himself in the following days after the return to his residence town. Therefore he was
provided with the proper vials and instructed on how to handle them. The samples were sent
by post to Forschungszentrum Karlsruhe. The sample collection protocol was set in order to
collect samples relating to the whole excretion.
As the samples were received, they were undergone to chemical preparation in order
to detect isotopes of Plutonium and Americium. Therefore for each collected sample the
separation procedure has provided two further samples, according to the block diagram of
Figure 2.4.1: one containing Plutonium isotopes, and the other one containing Americium.
On these samples alpha spectrometry was carried out by including them in the routine
measurement programme daily carried out by the FZK Toxicological Laboratory on samples
from the occupationally exposed workers.
2.4.3 RESULTS OF THE MEASUREMENTS
The results of the measurements for the collected blood, urine and feces samples are
given in Table 2.4.1 [151]. As previously stated the activity measurements on 239 Pu and 240 Pu
radioisotopes relate to the sum of their contributions. The activity in blood samples resulted
lower then the MDA for 238 Pu and 241 Am. For all the other kind of measurements ( 239 Pu+ 240 Pu
in blood and any radioisotopes in urine and feces samples) the activity values resulted to be
higher than the MDA.
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