It was shown that, during the annealing of samples at 550 to 950C under vacuum (10-3 Pa), the C impurity diffused from the interior to the surface of samples. The C diffusion flux which was directed towards the surface arose as a result of the formation of uranium oxymonocarbide, which contained C as an impurity, upon the surface in the presence of a low O partial pressure. The C diffusion rate in α-U grains depended upon the crystallographic orientation of the grains.

Carbon Diffusion in Uranium during Thermal Reprocessing in Vacuum. V.K.Orlov, V.S.Sergeev, M.A.Fomishkin, A.A.Rostovtsev, A.K.Kruglov: Atomic Energy, 2003, 95[2], 536-9