Sorption Of Plutonium Research Articles

Actinide behavior on crushed rock columns

The interactions of dissolved or colloidal actinides with tuffaceous rock are being studied at Los Alamos National Laboratory in support of the Nevada Nuclear Waste Storage Investigations project. We have used small columns of crushed tuff to obtain information on the sorption of neptunium, plutonium and americium during short (<1 day) time spans. Data from these experiments supplement information obtained from longer term batch-type experiments and provide insight concerning sorption kinetics, speciation, and colloid migration. We find that Np(V), Pu(VI) and Pu(V) show limited sorption on crushed tuff. Pu(IV) polymer and Am(III) are largely retained by the tuff, with a small fraction of the imput material moving through the column as colloids.

The Effect of Ground Water - Rock Interactions on the Migration of Redox Sensitive Radionuclides

ABSTRACTInteractions of redox sensitive elements with common Finnish rocks were studied in the laboratory under oxic and anoxic conditions. Sorption and diffusion of technetium, uranium, plutonium and neptunium were studied in drill cores of granites and gneiss. Cylindrical drill core cup samples and plane surfaces sawed from drill cores were exposed for periods from six to eighteen months to synthetic ground water to which Tc-99, U-233, Pu-236 or Np-237 had been added. Identification of the sorption and the diffusion pathways were discovered by qualitative autora-diography. The concentrations of elements versus depth in the drill core were measured radiometrically, by quantitative autoradio-graphy or by both methods. The migration of plutonium was slow in all samples. Technetium, uranium and neptunium were transported effectively under both oxic and anoxic conditions. Transported species of these elements were found throughout the rock matrices investigated - in microfissures, along mineral grain boundaries and in the minerals themselves. The ranges of the measured apparent diffusivities for neptunium were (2.7 – 30) × 10−14 m2/s under oxic conditions and (1.4 – 4.3) × 10−14 m2/s under anoxic conditions. For uranium the range of Da-values under oxic conditions was (3.6 – 5.7) × 10−14 m2/s under anoxic conditions it was (1.1 × 4.3) × 10−14 m2/s in granitic ground water and (1.8 – 5.3) × 10−14 m2/s in bentonite water.

AUTOSEP, an automated system for the quantitative ion exchange separation of plutonium from impurities

The anion exchange separation of interfering impurities from plutonium in the Dowex-1 8 N HNO3 system is a reliable purification method. An automated system, AUTOSEP, based on this manual procedure has been developed for greater productivity. Samples, in groups of ten, each containing 5–10 mg of plutonium are processed automatically in this system. AUTOSEP incorporates a means of programming reagent delivery, adjustment of the sample to the plutonium (IV) oxidation state via Fe(II) reduction/HNO3 oxidation, plutonium sorption on the resin in 8 N HNO3, washing of the resin bed with 8 N HNO3 to remove impurities, elution of the purified plutonium with 0.36 N HCl–0.01 N HF, and waste effluent disposal. The reagents are delivered by gravity from a module whose only moving parts are rotary valves. The eluted plutonium solutions are collected for subsequent controlled-potential coulometric analysis. The average recovery of plutonium determined by controlled-potential coulometry using this apparatus was 100.00% with a relative standard deviation of 0.10%.

Plutonium Activities in Soil Solutions and the Stability and Formation of Selected Plutonium Minerals

AbstractSelected thermodynamic data was used to develop solid phasesoil solution equilibria diagrams which are used to predict and understand plutonium behavior in terrestrial environments.The plutonium mineral transformations in soils are highly dependent upon the pH, Eh, and the soil solution composition. The predictions of weathering and formation sequences of Pu(OH)3, Pu(OH)4, PuO2(OH), PuO2(OH)2, PuO2, βPu2O3, PuF3, PuF4, PuO2CO3, and Pu(HPO4)2 at pH values from 3 to 11 at pO2 from 0.68 to 80, and in an assumed weathering environment are given. The study shows that the PuO2 is the most stable mineral in the pH and pO2 ranges found in the terrestrial environments.The nature and activity of ions and ion‐complexes and, hence, the total plutonium in solution is a function of the stable phase, pH, Eh, and complexing anions: for example, (i) in a reducing environment (pO2 80) at pH 8 and in equilibrium with PuO2(s), the predominant solution species are Pu3+ and its complexes, and (ii) in an oxidizing environment (pO2 16) at pH 8 and in equilibrium with PuO2(s), the predominant solution specie is PuO2CO3OH−.Empirical predictions regarding the plutonium sorption by soils are outlined and verified by experimental results reported in the literature. The deficiencies in the present thermodynamic data and future research needs are outlined.

Processing of Plutonium by Ion Exchange-VI. Plutonium (IV) Sorption Kinetics on Dowex 1×4 from Nitrate Solutions

The kinetics of the sorption of plutonium (IV) on Dowex 1 × 4 from nitrate solutions are presented. Sorption rates from various nitric acid and mixed aluminum-nitrate/nitric-acid solvents were stud...

A study on uranyl phosphates—IV: Sorption of some four-valent cations on ammonium uranyl phosphate

The dependence on concentration of uranyl and ammonium ions for the sorption of thorium, plutonium and zirconium ions on ammonium uranyl phosphate was investigated. By considering a precipitation mechanism of sorption equations were derived which are valid for the solution in contact with the sorbent. From the results obtained the approximate composition of the phosphates formed at sorption was found and approximate values of their solubility products were determined.

The properties of inorganic compounds in organic solvents—II The ion exchange reactions of quadrivalent plutonium in diethylene glycol dibutyl ether

The ion exchange reactions of plutonium(IV) nitrate extracted into diethylene glycol dibutyl ether (butex) from aqueous nitric acid have been investigated. For both cation and anion resins considerable sorption of plutonium occurred; in both systems, maximum values of K d were found at nitric acid concentrations in the solvent of about 0·4 M. The effect of nitric acid on the distribution coefficients has been correlated with the plutonium species present; in strong nitric acid plutonium(IV) appears to exist as solvated H 2Pu(NO 3) 6, Pu(NO 3) 4 having little stability in this solvent. The ion exchange behaviour has also been studied in solutions of perchloric acid in butex.