Abstract: The elution behaviors of ~(95)Zr, ~(95)Nb, ~(106)Ru, ~(144)Ce, ~(234)Th and U in solutionscontaining F~- and NO_3~- on the CL-TBP column were investigated. Pro-cedures were developed for the separation of ~(95)Zr, ~(95)Nb, ~(106)Ru and ~(144)Cefrom ~(234)Th and U. A method was established for the determination of gross β-and gross γ- radioactivity of fission products in UF_6. The standard deviationis ±3.5% for the samples with a gross β-activity amounting to 7.8% of thatof natural uranium, while the standard deviation is ±3.1% for the sampleswhose gross γ- activity amounts to 17% of that of natural uranium.