Download or read book FORM AND AGING OF PLUTONIUM IN SAVANNAH RIVER SITE WASTE TANK 18 written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report provides a summary of the effects of aging on and the expected forms of plutonium in Tank 18 waste residues. The findings are based on available information on the operational history of Tank 18, reported analytical results for samples taken from Tank 18, and the available scientific literature for plutonium under alkaline conditions. These findings should apply in general to residues in other waste tanks. However, the operational history of other waste tanks should be evaluated for specific conditions and unique operations (e.g., acid cleaning with oxalic acid) that could alter the form of plutonium in heel residues. Based on the operational history of other tanks, characterization of samples from the heel residues in those tanks would be appropriate to confirm the form of plutonium. During the operational period and continuing with the residual heel removal periods, Pu(IV) is the dominant oxidation state of the plutonium. Small fractions of Pu(V) and Pu(VI) could be present as the result of the presence of water and the result of reactions with oxygen in air and products from the radiolysis of water. However, the presence of Pu(V) would be transitory as it is not stable at the dilute alkaline conditions that currently exists in Tank 18. Most of the plutonium that enters Savannah River Site (SRS) high-level waste (HLW) tanks is freshly precipitated as amorphous plutonium hydroxide, Pu(OH){sub 4(am)} or hydrous plutonium oxide, PuO{sub 2(am, hyd)} and coprecipitated within a mixture of hydrous metal oxide phases containing metals such as iron, aluminum, manganese and uranium. The coprecipitated plutonium would include Pu{sup 4+} that has been substituted for other metal ions in crystal lattice sites, Pu{sup 4+} occluded within hydrous metal oxide particles and Pu{sup 4+} adsorbed onto the surface of hydrous metal oxide particles. The adsorbed plutonium could include both inner sphere coordination and outer sphere coordination of the plutonium. PuO{sub 2(am, hyd)} is also likely to be present in deposits and scales that have formed on the steel surfaces of the tank. Over the operational period and after closure of Tank 18, Ostwald ripening has and will continue to transform PuO{sub 2(am, hyd)} to a more crystalline form of plutonium dioxide, PuO{sub 2(c)}. After bulk waste removal and heel retrieval operations, the free hydroxide concentration decreased and the carbonate concentration in the free liquid and solids increased. Consequently, a portion of the PuO{sub 2(am, hyd)} has likely been converted to a hydroxy-carbonate complex such as Pu(OH)2(CO3){sub (s)}. or PuO(CO3) · xH2O{sub (am)}. Like PuO{sub 2(am, hyd)}, Ostwald ripening of Pu(OH)2(CO3){sub (s)} or PuO(CO3) · xH2O{sub (am)} would be expected to occur to produce a more crystalline form of the plutonium carbonate complex. Due to the high alkalinity and low carbonate concentration in the grout formulation, it is expected that upon interaction with the grout, the plutonium carbonate complexes will transform back into plutonium hydroxide. Although crystalline plutonium dioxide is the more stable thermodynamic state of Pu(IV), the low temperature and high water content of the waste during the operating and heel removal periods in Tank 18 have limited the transformation of the plutonium into crystalline plutonium dioxide. During the tank closure period of thousands of years, transformation of the plutonium into a more crystalline plutonium dioxide form would be expected. However, the continuing presence of water, reaction with water radiolysis products, and low temperatures will limit the transformation, and will likely maintain an amorphous Pu(OH)4 or PuO{sub 2(am, hyd)} form on the surface of any crystalline plutonium dioxide produced after tank closure. X-ray Absorption Spectroscopic (XAS) measurements of Tank 18 residues are recommended to confirm coordination environments of the plutonium. If the presence of PuO(CO3){sub (am, hyd)} is confirmed by XAS, it is recommended that experiments be conducted to determine if plutonium carbonates are transformed back into PuO{sub 2(am, hyd)} upon contact with grout.
Download or read book F Canyon Plutonium Solutions Savannah River Site Aiken County Barnwell County written by and published by . This book was released on 1994 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the Symposium on the Solidification and Long Term Storage of Highly Radioactive Wastes written by W. H. Regan and published by . This book was released on 1966 with total page 896 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-12 with total page 508 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evolution of Chemical Conditions and Estimated Plutonium Solubility in the Residual Waste Layer During Post Closure Aging of Tank 18 written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This document updates the Eh-pH transitions from grout aging simulations and the plutonium waste release model of Denham (2007, Rev. 1) based on new data. New thermodynamic data for cementitious minerals are used for the grout simulations. Newer thermodynamic data, recommended by plutonium experts (Plutonium Solubility Peer Review Report, LA-UR-12-00079), are used to estimate solubilities of plutonium at various pore water compositions expected during grout aging. In addition, a new grout formula is used in the grout aging simulations and apparent solubilities of coprecipitated plutonium are estimated using data from analysis of Tank 18 residual waste. The conceptual model of waste release and the grout aging simulations are done in a manner similar to that of Denham (2007, Rev. 1). It is assumed that the pore fluid composition passing from the tank grout into the residual waste layer controls the solubility, and hence the waste release concentration of plutonium. Pore volumes of infiltrating fluid of an assumed composition are reacted with a hypothetical grout block using The Geochemist's Workbench{reg_sign} and changes in pore fluid chemistry correspond to the number of pore fluid volumes reacted. As in the earlier document, this results in three states of grout pore fluid composition throughout the simulation period that are termed Reduced Region II, Oxidized Region II, and Oxidized Region III. The one major difference from the earlier document is that pyrite is used to account for reducing capacity of the tank grout rather than pyrrhotite. This poises Eh at -0.47 volts during Reduced Region II. The major transitions in pore fluid composition are shown. Plutonium solubilities are estimated for discrete PuO2(am, hyd) particles and for plutonium coprecipitated with iron phases in the residual waste. Thermodynamic data for plutonium from the Nuclear Energy Agency are used to estimate the solubilities of the discrete particles for the three stages of pore fluid evolution. In Denham (2007, Rev. 1), the solubilities in the oxidized regions were estimated at Eh values in equilibrium with dissolved oxygen. Here, these are considered to be maximum possible solubilities because Eh values are unlikely to be in equilibrium with dissolved oxygen. More realistic Eh values are estimated here and plutonium solubilities calculated at these are considered more realistic. Apparent solubilities of plutonium that coprecipitated with iron phases are estimated from Pu:Fe ratios in Tank 18 residual waste and the solubilities of the host iron phases. The estimated plutonium solubilities are shown. Uncertainties in the grout simulations and plutonium solubility estimates are discussed. The primary uncertainty in the grout simulations is that little is known about the physical state of the grout as it ages. The simulations done here are pertinent to a porous medium, which may or may not be applicable to fractured grout, depending on the degree and nature of the fractures. Other uncertainties that are considered are the assumptions about the reducing capacity imparted by blast furnace slag, the effects of varying dissolved carbon dioxide and oxygen concentrations, and the treatment of silica in the simulations. The primary uncertainty in the estimates of plutonium solubility is that little is known about the exact form of plutonium in the residual waste. Other uncertainties include those inherent in the thermodynamic data, pH variations from those estimated in the grout simulations, the effects of the treatment of silica in the grout simulations, and the effect of varying total dissolved carbonate concentrations. The objective of this document is to update the model for solubility controls on release of plutonium from residual waste in closed F-Area waste tanks. The update is based on new information including a new proposed grout formulation, chemical analysis of Tank 18 samples and more current thermodynamic data for plutonium and grout minerals. ...
Download or read book Plutonium Deadly Gold of the Nuclear Age written by Howard Hu and published by . This book was released on 1992 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mobilization of Plutonium IV from Savannah River Site Sediments written by Leo Gumapas and published by . This book was released on 2005 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Construction and Operation of a Mixed Oxide Fuel Fabrication Facility at the Savannah River Site written by and published by . This book was released on 2005 with total page 638 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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Download or read book Hearings on National Defense Authorization Act for Fiscal Year 1997 H R 3230 and Oversight of Previously Authorized Programs Before the Committee on National Security House of Representatives One Hundred Fourth Congress Second Session written by United States. Congress. House. Committee on National Security. Subcommittee on Military Procurement and published by . This book was released on 1997 with total page 916 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hearings on National Defense Authorization Act for Fiscal Year 1997 H R 3230 and Oversight of Previously Authorized Programs Before the Committee on National Security House of Representatives One Hundred Fourth Congress Second Session written by United States. Congress. House. Committee on National Security and published by . This book was released on 1997 with total page 928 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Public Works Appropriations written by United States. Congress. House. Committee on Appropriations and published by . This book was released on 1969 with total page 762 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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Download or read book Public Works Appropriations for 1969 for Water and Power Resources Development and the Atomic Energy Commission written by United States. Congress. House. Committee on Appropriations. Subcommittee on Public Works and published by . This book was released on 1968 with total page 2020 pages. Available in PDF, EPUB and Kindle. Book excerpt:
