For the production of the99Mo, the homogenity of the axial distribution of235U is a quality criterium for the production technology of the target fuel rods. The qualitative testing of the235U distribution is carried out by an automatic instrumentation by means of gamma ray measurement. The qualitative determination of the fluorescent radiation measurement was calculated by the determination of the uranium contents of calibration rods with the following separate analytical methods: X-ray fluorescence analysis, colorimetry and potentiometric titration. The accuracy of the determination of uranium by the method of gamma ray measurement is ≦ 1.5% uranium per centimeter of the target fuel rod.