A robust biamperometric titration methodology for the determination of uranium by Ti(III) reduction in the presence of plutonium

A biamperometric method is described for the determination of uranium in plutonium bearing nuclear fuel materials. Ti(III) is used for reducing U(VI) to U(IV) in 6 to 9M H2SO4 medium, followed by destruction of the excess reductant by HNO3. Plutonium is also reduced to Pu(III), but is selectively oxidized to Pu(IV) by the HNO2 produced in situ during the destruction of the excess Ti(III) by HNO3. The U(IV) is determined by titration with standard K2Cr2O7. Accuracy and precision of the method have been evaluated using different amounts of uranium ranging from 5 microgram to 20 milligram. The method has been applied to U determination in uranium oxides, uranium carbides, (U, Pu)O-2, (U, Th)O-2, (U, Pu)C and U-Al alloy. The method has also been employed for the determination of U present at very low levels (< 0.2%) in PuO2.