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Neptunium(V) sorption on quartz and albite in aqueous suspension; Annual progress report

Description: The behavior of neptunium in the subsurface environment is of interest since neptunium isotopes are included in nuclear waste. Previous work investigated the sorption behavior of Np onto {alpha}-Fe{sub 2}O{sub 3} (hematite), an accessory mineral of the Yucca Mountain repository. The work reported herein involves the much more abundant silicate minerals quartz and albite, and is a logical continuation of the ongoing task. In previous work increased sorption was observed in systems containing hematite and EDTA, a ligand which acts as a surrogate for organic complexing agents. In addition, increased partial pressures of CO{sub 2} are common in many ground waters and the effects of carbonate on sorption of radionuclides have to be studied as well. At concentration levels of 10{sup {minus}7} M, Np(V) does not adsorb strongly on quartz and albite up to pH values of approximately 9 at solid/solution ratios of 30 to 40 g/l. Significant adsorption (> 20%) occurs on both minerals only at pH > 9. Pretreatment of albite affects the sorption behavior of this mineral at pH > 9, possibly due to the formation of secondary mineral phases at the albite surface. EDTA does not adsorb on quartz at concentrations of 10{sup {minus}6} M. In the presence of 50 {mu}M EDTA, Np(V) sorption seems to be restricted. EDTA at the 10{sup {minus}6} M level adsorbs onto albite to an appreciable degree at pH values < 7.5. One {mu}M EDTA has no effect on Np(V) adsorption onto albite. Carbonate species adsorb on quartz and albite, both cases showing a maximum in sorption at pH 6.5 to 7 where HCO{sub 3}{sup {minus}} is the predominant solution species.
Date: October 1, 1991
Creator: Kohler, M. & Leckie, J.O.
Partner: UNT Libraries Government Documents Department

Pressure-Distribution Measurements on the Tail Surfaces of a Rotating Model of the Design BFW - M31

Description: In order to obtain insight into the flow conditions on tail surfaces on airplanes during spins, pressure-distribution measurements were performed on a rotating model of the design BFW-M31. For the time being, the tests were made for only one angle of attack (alpha = 60 degrees) and various angles of yaw and rudder angles. The results of these measurements are given; the construction of the model, and the test arrangement used are described. Measurements to be performed later and alterations planned in the test arrangement are pointed out.
Date: December 1949
Creator: Kohler, M. & Mautz, W.
Partner: UNT Libraries Government Documents Department

Upscaling of Long-Term U(VI) Desorption from Pore Scale Kinetics to Field-Scale Reactive Transport Models

Description: The focus of the project is the development of scientifically defensible approaches for upscaling reactive transport models (RTM) through a detailed understanding of U(VI) desorption across several spatial scales: bench-, intermediate-, and field-scales. The central hypothesis of the project is that the development of this methodology will lead to a scientifically defensible approach for conceptual model development for multicomponent RTM at contaminated DOE sites, leading to predictive transport simulations with reduced uncertainty.
Date: June 1, 2006
Creator: Steefel, Carl I.; Li, Li; Davis, J.A.; Curtis, G.P.; Honeyman, B.D.; Kent, D.B. et al.
Partner: UNT Libraries Government Documents Department