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Updated: May 18, 2026
12:22
Speciation and Bioavailability Measurements of Environmental Plutonium Using Diffusion in Thin Films
Published on: November 9, 2015
Controls on soluble Pu concentrations in PuO2/magnetite suspensions.
Andrew R Felmy1, Dean A Moore, Carolyn I Pearce
1Pacific Northwest National Laboratory, Richland, Washington, USA. ar.felmy@pnnl.gov
Environmental Science & Technology
|September 29, 2012
Summary
Mobilization of plutonium dioxide (PuO(2)(am)) was investigated. Competitive cations like Europium (Eu(III)) and Neodymium (Nd(III)) released significant aqueous plutonium, indicating solubilization from PuO(2)(am) rather than magnetite.
Area of Science:
- Environmental science
- Geochemistry
- Radiochemistry
Background:
- Plutonium dioxide (PuO(2)(am)) is a key species in nuclear waste.
- Understanding its long-term behavior and potential mobilization is crucial for environmental safety.
- Iron (Fe(II)) and magnetite (Fe(3)O(4)) are common in geological repositories and can influence radionuclide speciation.
Purpose of the Study:
- To investigate the time-dependent reduction and mobilization of amorphous plutonium dioxide (PuO(2)(am)).
- To assess the role of aqueous Fe(II) and magnetite nanoparticles in PuO(2)(am) transformation.
- To determine the influence of competitive cations on plutonium speciation and solubility.
Main Methods:
- Experiments were conducted over a range of pH values with aqueous Fe(II) and magnetite nanoparticles.
- PuO(2)(am) suspensions were monitored for aqueous plutonium concentrations over time.
- Equilibrium thermodynamic modeling was used to predict plutonium speciation.
- Europium (Eu(III)) and Neodymium (Nd(III)) were introduced as competitive cations.
Main Results:
- Limited aqueous plutonium mobilization was observed from PuO(2)(am) in early time frames (up to 56 days).
- Despite conditions favoring Pu(III) formation, significant Pu release did not occur initially.
- Introduction of Eu(III) or Nd(III) led to substantial release of aqueous plutonium.
- The source of mobilized plutonium was confirmed to be PuO(2)(am), not the magnetite nanoparticles.
Conclusions:
- The reduction of PuO(2)(am) to soluble Pu(III) is kinetically limited in the presence of Fe(II) and magnetite.
- Competitive cations play a significant role in mobilizing plutonium from its solid phase.
- Understanding these interactions is vital for predicting plutonium behavior in nuclear waste disposal environments.
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