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

2.2 A DESCRIPTION OF THE UPDATED CONTAMINATION CASE
The contamination incident investigated in the present work is one of the best
documented cases of a single intake of transuranium elements worldwide ( 238 Pu, 239 Pu, 240 Pu,
241 Pu, and 241 Am). This contamination case complies quite well the requirements previously
described for using a data set of occupational exposure for model verification purposes.
Furthermore it shows two important aspects:
• The measurements carried out in recent years in occasion of dose assessments
intercomparisons showed a significant enhancement of Plutonium urinary excretion,
particularly at long time after contamination. This was already pointed out, but at a lesser
extent, in other contaminated subjects [122];
• The Plutonium mixture introduced by the subject contains 241 Am too, giving the
possibility of carrying out direct measurements of organs activity burden, otherwise
hardly detectable in case of a contamination of pure Plutonium.
For such characteristics it was already proposed as a case study in different
intercomparisons on dose assessment. It is present as “Case 8” in the IAEA intercomparison
[123] and it is the base for “Case 6” in the 3 rd European intercomparison [124]. At the time of
the intercomparisons there was already a set of excretion and organ burden data from the first
day after the intake up to almost ten years [125]. Since 1983 direct measurements of
Americium burden in different organs were carried out also in Forschungszentrum Karlsruhe
[126]. In the frame of the present work in 1999 a complete follow-up of this case was carried
out in Forschungszentrum Karlsruhe and new data for the Plutonium and Americium amounts
in bioassays (urine, feces and blood) and for the Americium organs burdens were obtained.
The results of these direct and indirect measurements are extensively presented in the two
paragraphs 2.3.3 and 2.4.3, respectively.
2.2.1 THE CONTAMINATION EVENT
The working area where the contamination event occurred was a radiochemical
laboratory for the development of advanced nuclear fuel in a nuclear research centre. In the
laboratory nuclear fuels microspheres had been produced in a glove box using a special
gelling technique. The waste water resulting from this technique was routineously collected
and evaporated in the box. The residual waste water deriving from this process was
transferred into a second glove box for further evaporation and successive disposal.
The subject (male, 26 years old at that time, 91 kg weight, 179 cm height) was
working at the first glove box where the fuel microspehre were produced. On 24.05.83 at 4:15
PM an explosion occurred in the second glove box during the evaporation of three litres waste
water as a consequence of a unexpected exothermic reaction. The subject left the laboratory
immediately after the explosion, yet he resulted strongly contaminated at face, hairs and
clothes. He was immediately decontaminated in the radiation protection unit of the research
centre and nose swabs with bronchial slime samples were collected.
In the glove boxes the washing water contained Plutonium and Uranium in a mixture
of hydroxide gel with 10 % of ammonium nitrate and about 3.5 % of hexamethylentetramine.
The α activity composition of the substance causing the internal contamination of the subject
was 9 % 238 Pu, 55 % 239 Pu, 26% 240 Pu and 10 % 241 Am. The 241 Pu activity was 750 % of the
total α activity. Size distribution analysis of dust samples collected in the laboratory was also
carried out by means of scanning electron microscope exposures and x ray analyses. The
diameter of the particles containing Plutonium resulted to be between 3 and 40 µm.
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