Separation techniques for low-level determination of actinides in soil samples

Area of Science:

• Nuclear Chemistry
• Radiochemistry
• Analytical Chemistry

Background:

• Soil sample analysis is critical for environmental monitoring and nuclear waste management.
• Effective separation of actinides (e.g., Uranium, Thorium, Plutonium, Americium, Curium) is essential for accurate quantification and safe handling.
• Existing separation methods, while effective, can be improved for higher radiochemical recovery, especially for trivalent actinides.

Purpose of the Study:

• To develop and implement advanced separation methods for actinides in soil samples at PSI.
• To enhance the radiochemical recovery of trivalent Americium (Am) and Curium (Cm).
• To refine separation techniques for Plutonium (Pu) and Thorium (Th) while maintaining high efficiency.

Main Methods:

• Sample leaching followed by pre-concentration using oxalic acid precipitation.
• Utilizing extraction chromatographic resins (U/TEVA, TRU) and anion exchange (Dowex AG 1-X2).
• Implementing new methods stabilizing tetravalent Plutonium (Pu) and employing DGA resin for Americium (Am) and Uranium (U) separation.

Main Results:

• New methods successfully stabilize Pu in the tetravalent oxidation state, avoiding initial reduction.
• High distribution coefficients (k'-values > 10^4) for Am on DGA resin in nitric acid medium were achieved.
• Quantitative separation of Uranium (U) and Americium (Am) was achieved by adjusting nitric acid concentration, with Am eluted using HCl.

Conclusions:

• The implemented advanced separation methods significantly improve actinide recovery from soil samples.
• These refined techniques offer enhanced efficiency for separating trivalent actinides like Am and Cm.
• The developed methods provide a robust and effective approach for actinide analysis in complex matrices.