Chemical equilibrium is not characterized by equilibrium constants alone. At least one conservation principle is necessary.
Textbook descriptions of plutonium chemistry that are based on two-reaction-product disproportionation equations, or do not
recognize the conservation principles, are incomplete and potentially misleading.
Authors:M. Fülöp, N. Patzeltová, P. Ragan, and L. Mátel
The long-term effect of the plutonium to the human organism after Chernobyl accident was traced. Nine years after the accident the level of plutonium in the urine of the patients was in the order of tenths mBq.
A procedure for the determination of plutonium isotopes in soil is described. The method involves conversion of plutonium to acid-soluble form, dissolution, purification, electrodeposition and alpha-spectrometric determination. Final recovery is in the range from 27 to 51%. In this work increased attention was paid to the problem of equilibration of the chemical yield monitor with plutonium present in the soil sample.
Authors:Yan Wu, Hitoshi Mimura, and Yuichi Niibori
The uptake behavior of Pu(IV) has been investigated by using calcium alginate gel polymer (CaALG) and TBP microcapsules (TBP-CaALG).
The characterization of CaALG and TBP-CaALG was examined by SEM and IR, and the uptake properties and distribution of Pu(IV)
ions were estimated by batch method. The uptake rate of Pu(IV) on CaALG and TBP-CaALG in the presence of 5 M HNO3 was attained within 6 and 4 h, respectively, and Kd values for CaALG and TBP-CaALG after 7 h-shaking were 50.2 and 53.2 cm3/g, respectively. Relatively large Kd values (90.3–425 cm3/g) were obtained for fresh CaALG and TBP-CaALG in the presence of 0.5–2 M HNO3. Thus CaALG and TBP-CaALG are effective for the separation of Pu(IV) in the presence of highly concentrated HNO3.
A three-dimensional work surface for aqueous plutonium is illustrated. It is constructed by means of estimating work as a
function of the ambient pH and redox potential in a plutonium solution. The surface is useful for illustrating the chemistry
of disproportionation reactions. Work expressions are easier to use than work integrals.
Equilibrium prevails at all points in plutonium predominance region diagrams. Triple points combine equilibrium with equal
fractions of three Pu oxidation states. A rearrangement equation can be used to describe plutonium at a triple point. Two-reaction-product
disproportionation equations are not satisfactory for that purpose.
An experiment demonstrated the possibility of developing a zone refining process that would produce the first plutonium metal
of extremely high purity. Plutonium rods containing known amounts of impurities were melted inside tantalum boats and passed
horizontally through a three-turn, high-frequency coil so as to cause a narrow molten zone to pass through each rod 10 times.
The impurity elements cobalt, chromium, iron, nickel, neptunium, and uranium moved in the same direction as the molten zone,
as predicted; the elements aluminum, americium, and gallium moved in the opposite direction of the molten zone, as predicted.
As the impure alloy was zone refined, δ-phase plutonium metal crystals formed.
Charge balance equations can be used to obtain relationships among oxidation states in plutonium solutions. These equations are prepared from the initial conditions in the solution; they can be checked using equations of mass and charge conservation.
The precipitation behaviour of basic plutonium(IV) compounds from dilute nitric acid medium with aliphatic dicarboxylic acids has been investigated. Unlike plutonium(IV) oxalate, which is precipitated in acid medium (1–4M), the higher dicarboxylates precipitate in 0.9–2.5 pH range and their elemental analysis indicate Pu/dicarboxylate ratio of 11. The mode of formation, composition, solubility and thermal degradation behaviour for plutonium(IV) hydroxosuccinate has been studied. The hydroxy group determination by kinetic titration using fluoride complexing revealed that the compound has a Pu:OH ratio of 11 and determination of bridging oxygen group gave a Pu:O ratio of 10.5 suggest its formation as hydroxysuccinate having an oxobridged formula.
The plutonium processing facility at Los Alamos has adopted the strategic goal of becoming a facility that processes plutonium in a way that produces only environmentally benign waste streams. Pollution prevention through source reduction and environmentally sound recycling are being pursued. General approaches to waste reductions are administrative controls, modification of process technologies, and additional waste polishing. Recycling of waste materials, such as spent acids and salts, are technical possibilities and are being pursued to accomplish additional waste reduction. Liquid waste stream polishing to remove final traces of plutonium and hazardous chemical constituents is accomplished through (a) process modifications, (b) use of alternative chemicals and sorbents for residue removal, (c) acid recycling, and (d) judicious use of a variety of waste polishing technologies. Technologies that show promise in waste minimization and pollution prevention are identified. Working toward this goal of pollution prevention is a worthwhile endeavor, not only for Los Alamos, but for the Nuclear Complex of the future.