Interaction of ruthenium tetroxide with surfaces of nuclear reactor containment building

During a severe nuclear accident, different fission products will be released from the nuclear fuel and some of them may eventually reach the containment building. Ruthenium is considered to be an important fission product due to the possible formation of volatile oxides. Radiotoxicity and chemical toxicity of the volatile ruthenium compounds present a considerable hazard during a severe nuclear accident.

In this work, experiments regarding behavior of ruthenium tetroxide in the reactor containment were performed. The interactions of ruthenium tetroxide (RuO₄) with zinc, copper, aluminum and epoxy paint in dry and humid atmosphere were examined. SEM/EDX (scanning electron microscope/energy-dispersive X-ray spectroscopy), XPS (X-ray photoelectron spectroscopy) and EXAFS (extended X-ray absorption fine structure) techniques were used to identify the chemical composition of the deposits formed after the interaction of RuO₄ with the different materials. Additionally, distribution of ruthenium between different metals was examined.

Interaction of RuO₄ with the studied samples led to formation of dark, ruthenium-rich deposits. Examination of these deposits showed different chemical speciation of ruthenium on the surface when compared to the deeper layers of deposits. Interaction of RuO₄ with zinc, copper and aluminum resulted to different amounts of the deposited ruthenium on the metals.     

Interaction of ruthenium tetroxide with iodine-covered surfaces of materials in nuclear reactor containment building

Volatile iodine and ruthenium species are likely to be released from the fuel during a severe nuclear accident. Both iodine and ruthenium are expected to deposit on the surfaces in the containment building of the nuclear power plant. It is assumed that, due to the different release times from the fuel, ruthenium will reach the containment at the time when surfaces are already deposited with iodine species. The influence of ruthenium tetroxide on elemental iodine-covered surfaces in the containment of nuclear power plants was studied in this work. The ability of ruthenium tetroxide to oxidize iodine deposits on zinc, aluminum, copper and epoxy paint at high humidity conditions was evaluated. Quantification of both iodine and ruthenium deposits was done by the means of gamma spectroscopy. The chemical speciation of deposited elements was observed with SEM, XPS and EDX techniques. Experiments showed that ruthenium tetroxide oxidized iodine deposits into the volatile forms of iodine on zinc and aluminum samples and higher iodine oxides in the case of copper and epoxy paint samples. A major increase of ruthenium uptake on iodine-exposed surfaces in comparison to clean surfaces was observed.     

Persistent organic pollutants in plasma of delivering women from Arkhangelsk

The high levels of persistent organic pollutants have caused concern about human health, especially the health of the foetus and newborn child. This has especially been the case for Greenlandic and Canadian Inuits, where elevated levels of PCB and p,p'-DDE have been reported. In recent studies from arctic Russia the levels of beta-HCH and the DDT-group have been reported to be high, whereas the levels of PCB are low. However, the information from Northern Russia is, so far, incomplete. In this study, 27 delivering women from the city of Arkhangelsk, Russia, participated. They completed a questionnaire before delivery and plasma samples were collected after delivery. The analytical method developed to support this study involved gel permeation chromatography and silica gel purification, in addition to a traditional GC-MS method, and thus include acid labile compounds. The arithmetic mean levels of p,p'-DDE, beta-HCH and p,p'-DDT were 5.42, 3.59 and 1.17 microg/l, respectively. Toxaphene 26 and 50 were the only toxaphenes above the limit of detection, with arithmetic mean levels of 0.05 and 0.09 microg/l, respectively. Among the PCB congeners, PCB 138/163 was the most abundant with an arithmetic mean of 0.53 microg/l. The elevated levels of beta-HCH and p,p'-DDT as well as a low DDE/DDT ratio is a strong indication of fresh and maybe local sources in this area.     

Data Fusion of Fixed Detector and Probe Vehicle Data for Incident Detection

An important feature of many advanced traveler information systems (ATIS) is real-time information about incidents on the street network. This paper describes a system for automatically detecting incidents for such an ATIS developed using artificial neural networks and statistical prediction methods. The system monitors traffic conditions using two types of data: inductive loop detectors (ILDs) and vehicle probes. For both neural network and statistical methods, incident detection is accomplished using two approaches: by processing traffic input data directly and by processing the output of specialized algorithms that detect incidents using information from each data source. Analysis data generated from a simulation of a typical suburban signalized major arterial street are used. Different model configurations are examined and tested to identify the input variables and methods that are the best predictors of incident occurrence. The neural network approaches consistently perform at least as well as the discriminant analysis models, especially when results are adjusted to avoid false alarms.     

The social use of market processes in British and Hungarian housing policies

The switch of state subsidies away from support for public housing investment and towards an intensification of market processes is no longer the prerogative of Western countries, but, in the 1980s, has also become a feature of some state socialist societies. However, given the contrasting social, political and economic character of these societies, does the apparently similar process of privatisation in fact have the same characteristics, meaning and social consequences?

In this paper Britain and Hungary have been chosen as countries representative of the two social systems and in which market processes have intensified. The comparison begins by examining the social meaning of'owning’ and ‘renting’, the historical context of the development of housing policy, the allocation systems, rents, and subsidies. Focusing on the social housing sector the paper contrasts current housing issues. Particular attention is given to the “Right to Buy” policy which is a common feature in the 1980s of housing policy in both countries.

As a result of their mainly empirical comparison the authors conclude that privatisation in Britain and Hungary occurred in housing systems which have been similar in their tenure structure but very different in historical context. Because the broad social‐political context of privatisation is different, particularly the economic and institutional interests rooted within this issue, it is not inevitable that the regressive social consequences of measures which promote the privatisation process (which are common to both countries) are automatically negative in terms of the general sociological assessment.Thus comparison can help in the preparation of policy options and the assessment of new possibilities, but only as background. Strategies should be evaluated primarily against the social‐political context of each country and against the current policy objectives.     

Deformation and fracture behavior of polyamide nanocomposites: The effect of clay dispersion

This study describes the effect of the clay content and its dispersion on deformation and fracture behavior of polyamide nanocomposites. Two nanocomposite systems, intercalated and exfoliated nanocomposites containing layered silicate, were compared. They were prepared by melt‐compounding of polyamide with sodium montmorillonite or organophilized montmorillonite. It has been shown that while the exfoliated structure imparts to the nanocomposite higher stiffness and strength, the toughness is inferior to the intercalated nanocomposite. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Computational study of planar extrudate swell flows with a viscous liquid–gas interface

We present a computational study of planar extrudate swell flows of Newtonian liquids with a viscous liquid–gas interface. The model consists of the equations of motion coupled with the Boussinesq–Scriven constitutive equation for the interfacial stress tensor. The resulting set of equations is solved with the finite element method coupled with an elliptic mesh generation strategy to capture the free surface. The results show a detailed parametric study in terms of the capillary number and the Boussinesq number, a dimensionless parameter used to measure the ratio of viscous forces at the interface to viscous forces in the bulk liquid. The predictions reveal that the extrudate swells dramatically as the interfacial viscosity grows. The interfacial viscosity slows down the flow both in the bulk liquid and at the interface, and thus the extrudate size increases to conserve mass in the slow plug flow that develops under the free surface.     

Application of the limited-memory quasi-Newton algorithm for multi-dimensional,large flip-angle RF pulses at 7T

Objective

Ultrahigh field MRI provides great opportunities for medical diagnostics and research. However, ultrahigh field MRI also brings challenges, such as larger magnetic susceptibility induced field changes. Parallel-transmit radio-frequency pulses can ameliorate these complications while performing advanced tasks in routine applications. To address one class of such pulses, we propose an optimal-control algorithm as a tool for designing advanced multi-dimensional, large flip-angle, radio-frequency pulses. We contrast initial conditions, constraints, and field correction abilities against increasing pulse trajectory acceleration factors.

Materials and methods

On an 8-channel 7T system, we demonstrate the quasi-Newton algorithm with pulse designs for reduced field-of-view imaging with an oil phantom and in vivo with scans of the human brain stem. We used echo-planar imaging with 2D spatial-selective pulses. Pulses are computed sufficiently rapid for routine applications.

Results

Our dataset was quantitatively analyzed with the conventional mean-square-error metric and the structural-similarity index from image processing. Analysis of both full and reduced field-of-view scans benefit from utilizing both complementary measures.

Conclusion

We obtained excellent outer-volume suppression with our proposed method, thus enabling reduced field-of-view imaging using pulse trajectory acceleration factors up to 4.