Sequential Separation of Americium and Plutonium by Extraction Chromatography

The decision to use this method or a modified version of this method should be made during project planning (see Chapter 1). Project personnel, together with stakeholders, should determine the activities that need to be performed to ensure that this method is appropriate for use in the project (see Appendix B).

1.0 Scope and Application

This method is a fast sequential separation for Am/Cm and Pu in aqueous samples when present in ionic form. Additionally, provision has been made for eluting Np off the extraction column following the Pu and Am elution. The method applies to simple and complex aqueous matrices. It has been used on Hanford tank-waste samples and soil leachates of up to 1 g equivalent soil.

2.0 Summary of Method

The sample matrix is converted to 2.5 M HNO3. The oxidation state of the actinides is reduced because the pentavalent actinides do not extract onto the column; Fe is reduced to prevent its retention on the column. The sample is loaded on a prepared TRU•Spec® column. Most lanthanides, Am, Cm, Pu, and Np, are retained on the column and impurities are washed through the column. The Am and Cm are co-eluted with 9 M HCl and 4 M HCl. The Pu is eluted with 4 M HCl•0.1 M hydroquinone. Neptunium may be eluted next from the TRU•Spec® column with 0.1 M ammonium bioxalate. The Pu and Am fractions can be prepared for alpha spectrometry electrodeposition or precipitation plating.

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