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Abstract

The modified Davies and Gray method is frequently used for the potentiometric titration of uranium. It is based upon the reduction of U(VI) to U(IV) with a reductant (e.g. Fe"++") followed by a selective oxidation of the excess of reductant and subsequent titration of U(IV) with potassium dichromate (K-2Cr-20-7). Interference from other elements is low, but the method is rather cumbersome due to the number of reactants to be added before the titration is started. The timing of these additions also plays a role. In order to render the titration less dependent on human factors and with the aim of reaching high reproducibility, a computer controlled system has been designed and set up. Reagents are added by five computer controlled burettes. A program allows the choice of volumes and waiting times, and commands the start of the final titration which is followed by the microprocessor of the automatic potentiometric titrator. In this way a routine uranium tritration can be completed in about twelve minutes. Reproducibilities of the order of pm 0.15% are achievable in routine operation. For high precision work, the titrator is used as an end- point detector. Titrant is added manually by mass, so as to react with >99% of the uranium. The residual uranium is then titrated automatically by volume with diluted titrant. The precision can be improved by a factor of approximately ten.

Additional information

Authors: VERDINGH V, JRC GEEL ESTAB. (BELGIUM);MICHIELS A JRC GEEL ESTAB. (BELGIUM), JRC GEEL ESTAB. (BELGIUM)
Bibliographic Reference: JOURNAL OF NUCLEAR MATERIALS, VOL. 153 (1988), PP., 96-101
Record Number: 1989126101000 / Last updated on: 1989-06-01
Category: PUBLICATION
Available languages: en
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