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U.S. Department of Energy
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Colorimetric determination of reducing normality in the Purex process

Technical Report ·
OSTI ID:5457810

Adjustment of the valence state of plutonium from extractable Pu(IV) to nonextractable Pu(III) in the Purex process is accomplished by addition of reductants such as Fe(II), hydroxylamine nitrate (HAN), or U(IV). To implement on-line monitoring of this reduction step for improved process control at the Savannah River Plant, a simple colorimetric method for determining excess reductant (reducing normality) was developed. The method is based on formation of a colored complex of Fe(II) with FerroZine (Hach Chemical Company). The concentration of Fe(II) is determined directly. The concentration of HAN or U(IV), in addition to Fe(II), is determined indirectly as Fe(II), produced through reduction of Fe(III). Experimental conditions for a HAN-Fe(III) reaction of known stoichiometry were established. The effect of hydrazine, which stabilizes U(IV), was also determined. Real-time measurements of color development were made that simulated on-line performance. A laboratory analytical procedure is included. 5 references, 8 figures.

Research Organization:
Du Pont de Nemours (E.I.) and Co., Aiken, SC (USA). Savannah River Lab.
DOE Contract Number:
AC09-76SR00001
OSTI ID:
5457810
Report Number(s):
DP-1663; ON: DE84004047
Country of Publication:
United States
Language:
English