The three phases “dissolved solids”, “suspended solids” and “sediment” of four sampling sites along the river Isar were analysed
by INAA. In these as well as in the different grain-size fractions between<2 and 63 μm 17 trace elements were determined.
Compared with the values of other rivers in Middle Europe the river Isar is still below the levels of significant pollution.
Surface sorption experiments of U(VI) onto the surfaces of a Korean granite rock are carried out in order to investigate the
kinetics and reversibility of U(VI) sorption as a function of pH and surface types such as fresh intact surfaces and natural
fracture surfaces. It was shown that the effect of pH is significant in the sorption of U(VI) onto both types of the granite
surfaces. However the sorption rates do not greatly depend upon the pH regardless of the surface types. A two-step first order
kinetic behavior dominates onto both the intact surfaces and natural fracture surfaces of granite and that the linearization
approach of the kinetic model agrees well with experimental sorption data. The desorption results showed that the sorption
process of U(VI) was a little irreversible for the two types of granite surfaces regardless of pH and surface types. This
kinetic approach could give a better understanding of U(VI) sorption onto granite surfaces depending on pH and surface types.
Surface and bulk sorption of U(VI) onto granite rock with different types of surfaces were carried out and the results were compared for the different surfaces such as crushed granite, machined core granite, and core granite with fractured surface. The sorption behavior of U(VI) dependent on surface types was investigated and discussed for contacting time, pH, constituent minerals, and surface area. Results from the sorption experiments were also compared each other in order to analyze the differences in sorption behaviors of U(VI) and to correlate the surface sorption coefficient Ka and the bulk sorption coefficient Kd. The effect of contact time and pH on the sorption of U(VI) onto fractured surfaces was larger than that onto the machined fresh surfaces but smaller than that onto the crushed surfaces. As expected, it was noticed that the surface sorption coefficients of U(VI) for the natural fracture surfaces were greater than those of the machined fresh surfaces due to the higher content of secondary minerals such as calcite and chlorite which acted as stronger sorbents. It is presumed that there are many micro-fractures or micro-pores available for the uranium sorption on the granite surfaces, even on the machined fresh surfaces, and there can be an intrinsic difference between the surface and the bulk sorption due to the different types of surfaces.
The scavenging of UO22+ using 4-sulfonic calixarene in the presence of a strong adsorbent was studied as a function of pH. The adsorbent selected
was goethite because of its strong affinity for UO22+ and its abundance in natural soils. In order to understand the underlying chemistry of the scavenging process, the adsorption
of UO22+ and 4-sulfonic calixarene onto goethite, respectively, and the extraction of adsorbed UO22+ from goethite surface were modeled using the triple-layer model. The model well explained the pH dependence of the adsorption
and extraction processes. This work showed that maximum extraction was obtained around pH 10.5 in the presence of 12g/l goethite
in the case of a 1:3TU(VI):Tcalixareneratio.
Authors:J. Jung, S. Hyun, J. Lee, Y. Cho, and P. Hahn
The prediction of the adsorption behavior of natural composite materials was studied by a single mineral approach. The adsorption
of U(VI) on single minerals such as goethite, hematite, kaolinite and quartz was fully modeled using the diffuse-layer model
in various experimental conditions. A quasi-thermodynamic database of surface complexation constants for single minerals was
established in a consistent manner. In a preliminary work, the adsorption of a synthetic mixture of goethite and kaolinite
was simulated using the model established for a single mineral system. The competitive adsorption of U(VI) between goethite
and kaolinite can be well explained by the model. The adsorption behavior of natural composite materials taken from the Koongarra
uranium deposit (Australia) was predicted in a similar manner. In comparison with the synthetic mixture, the prediction was
less successful in the acidic pH range. However, the model predicted well the adsorption behavior in the neutral to alkaline
pH range. Furthermore, the model reasonably explained the role of iron oxide minerals in the adsorption of U(VI) on natural
Authors:L. Tandon, E. Hastings, J. Banar, J. Barnes, D. Beddingfield, D. Decker, J. Dyke, D. Farr, J. FitzPatrick, D. Gallimore, S. Garner, R. Gritzo, T. Hahn, G. Havrilla, B. Johnson, K. Kuhn, S. LaMont, D. Langner, C. Lewis, V. Majidi, P. Martinez, R. McCabe, S. Mecklenburg, D. Mercer, S. Meyers, V. Montoya, B. Patterson, R. Pereyra, D. Porterfield, J. Poths, D. Rademacher, C. Ruggiero, D. Schwartz, M. Scott, K. Spencer, R. Steiner, R. Villarreal, H. Volz, L. Walker, A. Wong, and C. Worley
The goal of nuclear forensics is to establish an unambiguous link between illicitly trafficked nuclear material and its origin.
The Los Alamos National Laboratory (LANL) Nuclear Materials Signatures Program has implemented a graded “conduct of operations”
type analysis flow path approach for determining the key nuclear, chemical, and physical signatures needed to identify the
manufacturing process, intended use, and origin of interdicted nuclear material. This analysis flow path includes both destructive
and non-destructive characterization techniques and has been exercized against different nuclear materials from LANL’s special
nuclear materials archive. Results obtained from the case study will be presented to highlight analytical techniques that
offer the critical attribution information.