Radon emanation thermal analysis (ETA) during ”step by step”heating to selected temperatures up to 1200oC in argon and subsequent cooling yielded detailed information on the annealing of radiation damage and macroscopic defects in a natural brannerite. Thermogravimetry showed mass losses in the temperature ranges 230-315, 570-760 and 840-1040oC. Mass spectrometry of the evolvedgases indicated M/Z = 44, i.e. CO2. Crystallization of initially amorphous brannerite was indicated by ETA in the temperature range 900-1020oC, in agreement with the X-ray diffraction results. From the radon diffusion activation energy values determined in ETA, the degree of structural ordering was assessed at different temperatures.