Metrology of radioactive aerosols : some rules for good mastery of particle sampling.
L. Grivaud, Forum RMS, 19-21/09/2001, Salon de Provence.
The metrology of aerosols radioactivity, not only requires the mastery of adioactivity measurement and techniques for natural activity compensation but also a good knowledge of particles behavior in order to monitor air radioactivity as representative as possible of the real atmosphere to be controlled.
However, it is impossible to sample aerosols without losing a more or less big fraction of particles. The knowledge of the mechanism which contributes to the loss of particles between the atmosphere to be monitored and the sampling filter allows to optimize the performances of the sampling line and to quantify the loss in the air circuit.
This presentation concern the following points :
- a reminder on the fundamental principles of aerosol physics,
- fundamental rules concerning sampling inlets design and their implantation,
- description of particle loss mechanism in sampling line, reduction techniques and quantifying,
- performances of some sampling filters tested for alpha radiation monitoring,
-some statements regarding the existing standards together with the new orientation of standards for aerosol sampling and radioactive aerosol monitoring.
The relations used in this presentation, nomenclature and physical constants are detailed pages 21 to 23.
LG-RMS-2 / 24