Measurement of resuspended aerosol in the Chernobyl area. I. Discussion of instrumentation and estimation of measurement uncertainty.

Results of measurements of the resuspended radioactive aerosols in the Chernobyl area are presented which were obtained soon after the Chernobyl reactor accident and in a European project in 1992-1993. The measurements were carried out with the intention of obtaining a data base for dose assessment of resuspended radioactive particles. Potential significant dose contributions may result from inhalation and secondary contamination due to resuspended radionuclides. In this first article of a series of three papers, the instrumentation and the measurement uncertainties are discussed. An effort was made to sample quantitatively giant aerosol particles (particles larger than 10 microns aerodynamic diameter) as well. The comparison of the samplers shows, in general, an agreement of concentration measurements of 137Cs and 7Be within a factor of two. One sampler was identified with larger discrepancies and needs additional investigation of its sampling characteristics; for another device, the recalibration of the analysing system is recommended. Ordinary integrating samplers have a loss of about 30% in 137Cs activity compared to an isokinetic sampler collecting giant particles as well. The mean ratio of 137Cs activity concentration between an instrument sampling only particles larger than 10 microns and an ordinary integrating sampler is 0.39 +/- 0.15 during anthropogenic-enhanced resuspension. These findings demonstrate the significant contribution of giant particles to resuspended airborne radioactivity. The results of this study concerning integral measurements during wind-driven resuspension proved to be in good agreement with previously published data on resuspension.