Determination of 235U isotopic abundance by fission-yield difference method

Based on neutron activation analysis, a new method was presented for the determination of uranium isotopic abundance, in which fast neutrons generated by T (d, n) 4He were used to induce fission in uranium samples. The exponential relation between different abundances of 235U and the average fission-yield ratios of specific fission products was employed in this method. Taking the fission-yield ratios of specific fission products, such as Y¯88Rb/Y¯107Rh, Y¯88Rb/Y¯135I, Y¯88Rb/Y¯104Tc and Y¯92Sr/Y¯104Tc as the subjects of research, the relation curves between the average yield ratios and the 235U isotopic abundance as well as the expressions (Y¯i/Y¯j=f(H0)) for the average yield ratio (Y¯i/Y¯j) as a function of the 235U isotopic abundance (H0) were obtained. To verify the precision and accuracy of this method, 5 tests using each working curve were conducted for simulated samples with a 235U abundance of 72.2%, and the relative standard deviation (RSD) of all tests was less than 2%. Compared to the γ energy spectrum method, the relative error of each measurement result was between 1.11% and 1.66%.