The ultrafast sweep reflectometry technique is used to investigate plasma turbulence on Tore Supra. Thanks to the X-mode polarization, the plasma density and fluctuations over the whole tokamak radius, from the far scrape-off layer (SOL) to the core can be measured. Cross-correlation analysis is applied to all the signal components to estimate the fluctuation correlation length radial profile. The correlation length decreases from the plasma centre to the last closed flux surface and grows again into the far SOL.