[Use of track detector for the measurement of urine plutonium]

In case of internal exposition by inhalation of plutonium compounds, the faecal excretion is many times higher than in urine. In case of emergency, the faecal analysis is, of course, the best control. But in case of chronic exposure, the urine analysis are better tolerated by workers and easier for the laboratory organization. The results presented pertain to Plutonium 239: the chemical separation is quite conventional but a track detection is used for counting. It was first necessary to optimise both, the thickness of the screen placed between the radioactive source and the detector, and the chemical treatment for transforming the tracks into holes. Three minutes were required to count the perforations by moving the detector across a spark system. Due to detector background and efficiency, a 30 day exposure time is required to detect 0.2 mBq of Plutonium 239 (that's enough in relation to legal limits).