Analytical techniques for charactering radioactive particles deposited in the environment.

Since 1945, a series of nuclear and radiological sources have contributed to the release of radioactive particles containing refractory elements into the environment. Several years of research have demonstrated that the particle composition will depend on the source, while the release scenarios will influence particle properties of relevance for environmental transfer. Radioactive particles can also carry sufficient amount of radioactivity (MBq) and represent point sources of radiological concern. Most radiological assessment models, however, are based on bulk concentrations, assuming that radionuclides in the environment are evenly distributed. In contrast, radioactive particles and thereby doses are unevenly distributed, while leaching of radionuclides from particles prior to measurements can be partial, potentially leading to underestimation of inventories. For areas affected by particle contamination, information on particle characteristics controlling the particle weathering rates and remobilization of particle associated radionuclides will therefore be essential to reduce the overall uncertainties of the impact assessments. The present paper will focus on analytical strategies, from screening techniques applicable for identifying hot spots in the field, fractionation techniques and single particle extraction techniques as a preparatory mean to apply non-destructive solid state speciation techniques, till leaching techniques applied sequentially to obtain information on binding mechanisms, mobility and potential bioavailability. Thus, a combination of techniques should be utilized to characterize radioactive particles in order to improve environmental assessments for areas affected by radioactive particle fallout.