A transmission-corrected -ray counting method has been employed for the assay of uranium in crude Na2U2O7 cakes produced at the Uranium Conversion Facilities. A 3×3 NaI(TI) detector was used in conjunction with a 400-channel analyzer. The observed count rate of the 1 MeV -ray emitted by the238U in the sample was corrected for sample self-attenuation, measured with a65Zn (-energy 1115 keV) transmission source. A calibration factor determined by measuring a standard of known amount of radioactive material in the same form and geometry as the unknown sample was used to convert the transmission corrected count rate to the amount of uranium in the weighted sample. Another -spectrometric method is described for the assay of the U-content in the MgF2 slag produced during the magnesiothermic reduction of UF4 to U-metal ingots at the natural U-conversion plant.