The Role of Pu(III) in Groundwater Contaminant and Repository Assessments
Explore the source record for details and available documents.
Earth Sciences↗
Engineering topics
Reed, Donald T.
Publications and source records attributed to Reed, Donald T..
Pu( iii ) and Cm( iii ) in the presence of EDTA: aqueous speciation, redox behavior, and the impact of Ca( ii )
Combined advanced spectroscopy and solubility studies provide evidence for the formation of novel calcium-containing and hydrolyzed (Cm,Pu)( iii )–EDTA complex(es).
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Plutonium Redox and the WIPP Oxidation State Distribution Model
Explore the source record for details and available documents.
Energy Sciences↗
Plutonium in the WIPP
Explore the source record for details and available documents.
Inorganic and Physical Chemistry↗
Influence of ethylenediaminetetraacetic acid on the long-term oxidation state distribution of plutonium
Here, spectrophotometry was used to study the effect of EDTA on plutonium oxidation state distribution as a function of time, pH, and ligand-to-metal ratio (L/M) under anoxic conditions. Novel Pu(V)-EDTA absorption bands were identified at 571, 993, 1105, and 1150 nm with molar absorption coefficients of 15 ± 1, 6 ± 1, 10 ± 1, and 10 ± 1 cm –1 M –1 , respectively. Pu(V)-EDTA spectral changes occurred at L/M < 1, indicating only Pu V O 2 (EDTA) 3- formed with logK = 3.6 ± 0.3. Time-resolved experiments showed EDTA drastically increased the Pu(V/VI) reduction rate, which we propose is driven by amine lone-pair electron donation and the oxidative decarboxylation of EDTA. Oxidation of Pu(III)-EDTA to Pu(IV)-EDTA occurred on a slower time scale (110–237 days) than previously reported (<15 min) and is hypothesized to be radiolysis driven. Pu(V/VI)-EDTA and Pu(III)-EDTA both approached Pu(IV)-EDTA stabilization over time, yet Pu(V/VI)-EDTA solubility data was ≥ 1.0 log 10 units higher than predicted by Pu(IV)-EDTA solubility models, indicating that current thermodynamic models are incomplete. Ultimately, the data show EDTA preferentially stabilizes Pu(IV) over time regardless of initial oxidation state, but Pu(V)-EDTA can persist under environmentally-relevant conditions, emphasizing the need to continue investigating redox reactions, speciation, and behavior of these complexes to support the transuranic waste disposal and surface remediation/containment efforts.
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
Actinide/Chemistry Modeling and Microbial Activities in Saline Systems
Explore the source record for details and available documents.
Biological Science↗
Systematic Calculation of Pu Pourbaix Diagrams: Modelling Support for the LANL ACRSP Team
The report enclosed entitled “Systematic Calculation of Pu Pourbaix Diagrams: Modelling Support of the LANL ACRSP Team” was prepared by Amphos21 under contract to the Los Alamos National Laboratory Actinide Chemistry and Repository Science Program (ACRSP) team to support an enhanced understanding of the actinide and brine chemistry in the Waste Isolation Pilot Plant (WIPP) transuranic repository. In this report, the ThermoChimie chemistry model and database, with some slight modifications, were used to calculate Pourbaix diagrams to investigate the effects of ionic strength, organic complexation, and metal competition on the predominance diagrams for aqueous and solid plutonium species under the anoxic and reducing conditions expected in the repository. These diagrams were connected to iron chemistry phase diagrams since this iron chemistry is expected to define and control redox properties in the WIPP repository concept.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗