Experimental determination of U diffusion in α-Zr

U bulk diffusion in a-Zr was measured by mean a-spectrometry in the temperature range 763?1123 K(540?850 C). A deviation from the Arrhenius law consistent in a downward curvature was observed;such anomaly is similar to the self and hetero substitutional diffusion previously measured in a-Zrmatrix.The measurements are compatible with the existences of migrating Fe?vacancy complex that could becompetitive with a simplest single vacancy mechanism for substitutional diffusers. The possibility thatthis could be the reason for the non Arrhenius behaviour is discussed.