DETERMINATION OF THE PHYSICAL AND CHEMICAL PROPERTIES, BIOKINETICS, AND DOSE COEFFICIENTS OF URANIUM COMPOUNDS HANDLED DURING NUCLEAR FUEL FABRICATION IN FRANCE

The introduction of new ICRP recommendations, especially the new Human Respiratory Tract Model (HRTM) in ICRP Publication 66 led us to focus on some specific parameters related to industrial uranium aerosols collected between 1990 and 1999 at French nuclear fuel fabrication facilities operated by COGEMA, FBFC, and the CEA. Among these parameters, the activity median aerodynamic diameter (AMAD), specific surface area (SSA), and parameters describing absorption to blood fr, sr and ss defined in ICRP Publication 66 were identified as the most relevant influencing dose assessment. This study reviewed the data for 25 pure and impure uranium compounds. The average value of AMAD obtained was 5.7 &mgr;m (range 1.1–8.5 &mgr;m), which strongly supports the choice of 5 &mgr;m as the default value of AMAD for occupational exposures. The SSA varied between 0.4 and 18.3 m2 g−1. For most materials, values of the absorption parameters fr, sr, and ss derived from the in vitro experiments were generally consistent with those derived from the in vivo experiments. Using average values for each pure compound allowed us to classify UO2 and U3O8 as Type S, mixed oxides, UF4, UO3 and ADU as Type M, and UO4 as Type F based on the ICRP Publication 71 criteria. Dose coefficients were also calculated for each pure compound, and average values for each type of pure compound were compared with those derived using default values. Finally, the lung retention kinetics and urinary excretion rates for inhaled UO3 were compared using material-specific and default absorption parameters, in order to give a practical example of the application of this study.