Atmospheric samplings of aerosols produced during fires of D.U shells against the turret and the glacis of a tank have been realised in collaboration with the French army. The shell was made with 99% of depleted reprocessed uranium and many others elements from the armour.
The collection of dusts on filters and impactors allowed us to determine the activity concentration around (at 1, 2.5 and 4 meters) and inside the tank and the granulometric distribution of aerosols. The results showed that the AMAD of the particles were 1 µm for the fire against the glacis and 2 µm for the turret, with geometric standard deviation of 3.7 and 2.5 respectively. The mean activity concentration measured around the tank was 120 Bq.m-3, i.e. 8.5 mg.m-3 of D.U, according to a specific activity of 14 kBq.g-1.
Filters have been also analysed by S.E.M linked with a X-ray analyser and by X-ray diffraction to determine respectively the morphology, the elementary composition of the dusts and the types of uranium oxides formed. There were two types of particles (fine particles and large molten particles) composed mainly with a mixture of uranium and an element of the armour. The uranium oxides formed during the fires were mainly U3O8 and UO2.25, and probably UO3.01 and a mixture U/armour’s element.
The kinetics of the chemical dissolution of these dusts in three media (water, HCl and Gamble’s solution) has been determined using in vitro tests. These solubilities were found to be respectively slow, moderate and intermediate between slow and moderate.
Dose coefficients have been calculated using LUDEP for the glacis and the turret’s aerosols and have been compared with the default values given by ICRP. Finally, a comparison with experimental results obtained from french industrial uranium oxides and from the open litterature on D.U ammunitions, is also presented.
(1) Institut de Protection et de Sûreté Nucléaire, Département de Protection de la santé de l'Homme et de Dosimétrie, Service de Dosimétrie, Laboratoire d’Etudes Appliquées de Radiotoxicologie, BP n°38, F 26701 Pierrelatte, France
(2) Service de Protection Radiologique
(3) Centre de Recherche du Service de Santé des Armées