Investigation of the Sampling Conditions of Aerosols for the Monitoring of Ventilation Air

Kurzfassung

The activity surveillance of a nuclear stack waste repository includes monitoring of the stack effluent as an outstanding task. For probe sampling it is prescrible to use a 2-dimensional arrangement of a certain number of single probes. The particle distribution has to satisfy definite homogeneity conditions over the sampling area. Thus it is subject of the present experiments to observe the spatial distribution of the particle number density in the stack section of interest in order to optimize the positioning of the sampling area. The experiments were carried out at a 1:10 model of the stack of the repository project. The present paper deals with a non intrusive optical two dimensional field measurement technique that can determine the spatial distribution of particles, from this the concentration of particles of the measurement plane can be concluded. The concentration of particles must be low enough to allow isolated particles to be distinguished on a single image. In comparison with local measurements using probes this kind of measurement has the advantage of not disturbing the flow and of delivering a spatial information. This is how the effects of changing parameters can be made out. Parameters like this might be different in measurements utilizing probes without being recognized