Public Safety Aspects of Nuclear Power Plant Licensing

Various aspects of the siting, design, construction and operation of nuclear power plants to which the Atomic Energy Commission gives attention in its licensing activities are discussed, together with the reasons why they are considered important to public safety. This includes the measures taken to assure the integrity of the nuclear fuel and primary coolant system under all operating conditions; to provide adequate means of coping with emergency situations; and to limit the consequences of accidents to levels which do not endanger the health and safety of the public.     

Increasing soft classification accuracy through the use of an ensemble of classifiers

Although soft classification analyses can reduce problems such as those associated with mixed pixels that impact negatively on conventional hard classifications their accuracy is often low. One approach to increasing the accuracy of soft classifications is the use of an ensemble of classifiers, an approach which has been successful for hard classifications but rarely applied for soft classifications. Four methods for combining soft classifications to increase soft classification accuracy were assessed. These methods were based on (i) the selection of the most accurate predictions on a class‐specific basis, (ii) the average of the outputs of the individual classifications for each case, (iii) the direct combination of classifications using evidential reasoning and (iv) the adaptation of the outputs to enable the use of a conventional (hard classification) ensemble approach. These four approaches were assessed with classifications of National Oceanic and Atmospheric Administration (NOAA) Advanced Very High‐Resolution Radiometer (AVHRR) imagery of Australia. The data were classified using two neural networks and a probabilistic classifier. All four ensemble approaches applied to the outputs of these three classifiers were found to increase classification accuracy. Relative to the most accurate individual classification, the increases in overall accuracy derived ranged from 2.20% to 4.45%, increases that were statistically significant at 95% level of confidence. The results highlight that ensemble approaches may be used to significantly increase soft classification accuracy.     

Rational Co‐Design of Polymer Dielectrics for Energy Storage

Although traditional materials discovery has historically benefited from intuition‐driven experimental approaches and serendipity, computational strategies have risen in prominence and proven to be a powerful complement to experiments in the modern materials research environment. It is illustrated here how one may harness a rational co‐design approach—involving synergies between high‐throughput computational screening and experimental synthesis and testing—with the example of polymer dielectrics design for electrostatic energy storage applications. Recent co‐design efforts that can potentially enable going beyond present‐day “standard” polymer dielectrics (such as biaxially oriented polypropylene) are highlighted. These efforts have led to the identification of several new organic polymer dielectrics within known generic polymer subclasses (e.g., polyurea, polythiourea, polyimide), and the recognition of the untapped potential inherent in entirely new and unanticipated chemical subspaces offered by organometallic polymers. The challenges that remain and the need for additional methodological developments necessary to further strengthen the co‐design concept are then presented.     

Raman Studies of ${rm Ti}_{bm{ 1-x}} {rm Fe}_{bm x} {rm O}_{bm 2}$ Nanoparticles

Ti_1-xFe_xO₂ (x = 0.00-0.13) nanoparticle samples were prepared by hydrolysis method. We investigated the effects of Fe doping on the structural and magnetic properties of the Ti_1-xFe_xO₂ nanoparticle system. Scanning electron microscopy and X-ray diffraction measurements confirm that the particle size of the powder is in nanoscale, and that the magnetic Fe impurities substitute for the Ti sites in the anatase TiO₂ phase. All the samples with x > 0 were found to be super-paramagnetic at room temperature by magnetization measurements. Raman spectra also strongly support that the Fe atoms go into the Ti-site in theTiO₂ structure. For comparison, ceramic Ti_1-xFe_xO₂ samples were also prepared by usual ceramic method. Ferromagnetism was observed only in the ceramic Ti_1-xFe_xO₂ system. Additional Raman peak at around 610 cm^-1 is observed only in the ceramic samples. This may be related to the clusters created by mixture of various valence state of Fe, which probably would be the cause for ferromagnetism observed in the ceramic Ti_1-xFe_xO₂ system.     

Solute effects on solvent electromigration in dilute alloys

The effects of a small concentration of solute on solvent electromigration are due to an enhancement effect of the solute atoms on the solvent diffusivity (which gives rise to the factor b′) and a ”vacancy flow effect” proportional to the flux of solute and to the term L_AB/L_BB. The theoretical expressions of b′ and L_AB/L_BB are given for f.c.c. and b.c.c. alloys. This dependence of solvent electromigration on the solute concentration can be combines with the solute diffusivity and solvent-enhanced diffusion to determine the various vacancy jump frequency ratios in binary dilute alloys.The validity and the interest of this new method are illustrated by the first experiments, performed on $\text{Ag}$Zn, $\text{Ag}$Cd and $\text{Al}$Cu.     

Innovative in situ investigations using synchrotron-based micro tomography and molecular dynamics simulation for fouling assessment in ceramic membranes for dairy and food industry

Proteins in dairy streams result in organic fouling and function loss for ceramic membrane's porous structure. Synchrotron-based X-ray microtomography (SR-µCT) is a new method with a high signal to noise ratio and accordingly significant level of accuracy. The goal of this study was to perform an in situ assessment of ceramic membrane fouling in the dairy stream filtration process, using SR-µCT. This study attempted to assess porosity variation and membrane fouling through different layers from the top, middle, and bottom layers of the ceramic microfiltration membrane before and after skimming milk filtration. Molecular dynamics simulation (MDS) was used for depth understanding of milk protein interactions with the ceramic membrane. Fouling was found to be more intense on the top of the ceramic membrane even though the top layer was slightly more porous, which indicates that top layers were more prone to fouling. A regression model was derived to correlate the porosity loss due to membrane fouling at different membrane thicknesses. The MDS results showed more affinity of the milk proteins to the ceramic membrane compared to water molecules. The MDS studies showed how the presence of the milk's protein macromolecules could change the hydrophilicity trend on the membrane's surface.     

Re‐Use of Marble Stone Powders in Producing Unsaturated Polyester Composites

The main goal of this study is to evaluate the potential of waste stone powders as filler in composite materials with a matrix of unsaturated polyester. These wastes are generated in the form of stone fragments and stone‐cutting sludge. Ground marble wastes are thoroughly characterized with the aim to use them as fillers: Mineralogical and chemical composition, particle size distribution, and morphology of these waste stone powders are investigated. Unsaturated polyester resin composites with the different stone powder fillers are prepared. The influence of powder type on the composites’ mechanical properties (tensile, bending, impact, and hardness characteristics), water resistance, thermal stability as well as surface fracture morphology of composites are studied. The moduli of the composites increase by 100%, the hardness of the composites may be improved by 80% upon loading with the “waste” filler, leading to an economical material and helping to reduce waste.

     

Synthesis of Ag-AgBr/Al-MCM-41 nanocomposite and its application in photocatalytic oxidative desulfurization of dibenzothiophene

A series of Ag-AgBr/Al-MCM-41 nanocomposites were synthesized by dispersion of Ag-AgBr on mesoporous silica Al-MCM-41 obtained from natural bentonite. The synthesized Ag-AgBr/Al-MCM-41 composites with Ag nanoparticles growing on the surface of Al-MCM-41 were used for photocatalytic oxidative desulfurization of dibenzothiophene. The physical properties of Ag-AgBr/Al-MCM-41 were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Ultraviolet–visible diffuse reflection spectroscopy (UV–Vis DRS), photoluminescence (PL) emission spectra, and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity results showed that in the presence of 40% Ag-AgBr/Al-MCM-41 photocatalyst the oxidative desulfurization of dibenzothiophene reached the maximum efficiency at 99.22% and the photocatalytic activity still keeps high level after four cycles.