Separating the Minor Actinides Through Advances in Selective Coordination Chemistry

This report describes work conducted at the Pacific Northwest National Laboratory (PNNL) in Fiscal Year (FY) 2012 under the auspices of the Sigma Team for Minor Actinide Separation, funded by the U.S. Department of Energy Office of Nuclear Energy. Researchers at PNNL and Argonne National Laboratory (ANL) are investigating a simplified solvent extraction system for providing a single-step process to separate the minor actinide elements from acidic high-level liquid waste (HLW), including separating the minor actinides from the lanthanide fission products

Pacific Northwest Laboratory annual report for 1993 to the DOE Office of Energy Research. Part 1: Biomedical Sciences

This report summarizes FY 1993 progress in biological and general life sciences research programs conducted for the Department of Energy`s Office of Health and Environmental REsearch (OHER) at Pacific Northwest Laboratory (PNL). This research provides knowledge of fundamental principles necessary to identify, understand, and anticipate the long-term health consequences of exposure to energy-related radiation and chemicals. The Biological Research section contains reports of studies using laboratory animals, in vitro cell systems, and molecular biological systems. This research includes studies of the impact of radiation, radionuclides, and chemicals on biological responses at all levels of biological organization. The General Life Sciences Research section reports research conducted for the OHER human genome program

Separating the Minor Actinides Through Advances in Selective Coordination Chemistry

This report describes work conducted at the Pacific Northwest National Laboratory (PNNL) in Fiscal Year (FY) 2012 under the auspices of the Sigma Team for Minor Actinide Separation, funded by the U.S. Department of Energy Office of Nuclear Energy. Researchers at PNNL and Argonne National Laboratory (ANL) are investigating a simplified solvent extraction system for providing a single-step process to separate the minor actinide elements from acidic high-level liquid waste (HLW), including separating the minor actinides from the lanthanide fission products

Sludge Treatment and Extraction Technology Development: Results of FY 1993 studies

This report describes experimental results from work conducted in FY 1993 under the Sludge Treatment and Extraction Technology Development Task of the Tank Waste Remediation System (TWRS) Pretreatment Technology Development Project at Pacific Northwest Laboratory (PNL). Experiments were conducted in the following six general areas: (1) sludge washing, (2) sludge leaching, (3) sludge dissolution, (4) actinide separation by solvent extraction and extraction chromatography, (5) Sr separation by solvent extraction, and (6) extraction of Cs from acidic solution

Removing Phosphate from Hanford High-Phosphate Tank Wastes: FY 2010 Results

The U.S. Department of Energy (DOE) is responsible for environmental remediation at the Hanford Site in Washington State, a former nuclear weapons production site. Retrieving, processing, immobilizing, and disposing of the 2.2 × 105 m3 of radioactive wastes stored in the Hanford underground storage tanks dominates the overall environmental remediation effort at Hanford. The cornerstone of the tank waste remediation effort is the Hanford Tank Waste Treatment and Immobilization Plant (WTP). As currently designed, the capability of the WTP to treat and immobilize the Hanford tank wastes in the expected lifetime of the plant is questionable. For this reason, DOE has been pursuing supplemental treatment options for selected wastes. If implemented, these supplemental treatments will route certain waste components to processing and disposition pathways outside of WTP and thus will accelerate the overall Hanford tank waste remediation mission

Organic and Aqueous Redox Speciation of Cu(III) Periodate Oxidized Transuranium Actinides

A hexavalent group actinide separation process could streamline used nuclear fuel recycling and waste management. The limiting factor to such a process compatible with current fuel dissolution practices is obtaining and maintaining hexavalent Am, AmO₂²⁺, in molar nitric acid because of the high reduction potential of the Am­(VI)/Am­(III) couple (1.68 V vs SCE). Two strong oxidants, sodium bismuthate and Cu³⁺ periodate, have demonstrated quantitative oxidation of Am under molar acid conditions, and better than 50% recovery by diamyl amylphosphonate (DAAP) is possible under these same conditions. This work considers the use of Cu³⁺ periodate to oxidize Np­(V) to Np­(VI) and Pu­(IV) to Pu­(VI) and to recover these elements by extraction with DAAP. A metal:oxidant ratio of 1:1.2 and 1:3 was necessary to quantitatively oxidize Np­(V) and Pu­(IV), respectively, to the hexavalent state. Extraction of hexavalent Np, Pu, and Am by 1 M DAAP in n-dodecane was measured using ultraviolet–visible (PuO₂²⁺, AmO₂²⁺) and near-infrared (NpO₂²⁺) spectroscopy. Distribution values of AmO₂²⁺ were found to match previous tracer level studies. The organic phase spectra of Np, Pu, and Am are presented, and molar absorptivities are calculated for characteristic peaks. Hexavalent Pu was found to be stable in the organic phase, while NpO₂²⁺ showed some reduction to NpO₂⁺; Am was present as Am³⁺, AmO₂⁺, and AmO₂²⁺ species in aqueous and organic phases during the extraction experiments. These results demonstrate, for the first time, the ability to recover macroscopic amounts of americium that would be present during fuel reprocessing and are the first characterization of Am organic phase oxidation state speciation relevant to a hexavalent group actinide separation process under acidic conditions