PIXE as a complement to trace metal analysis of sediments by ICP-OES

The adverse effects of metal contamination in sediments require methods that can quickly and accurately assess the extent of environmental pollution. Particle induced X-ray emission spectrometry (PIXE) is demonstrated to be a viable alternative to an established method, which consists of acid digestion and Inductively coupled plasma-optical emission spectrometry (ICP-OES) to measure trace metals in sediment. The analysis of trace metal composition by both techniques on a NIST Standard Reference Material mud gives results that are consistent with the certified values for fourteen measured metals, seven of which are common to both methods. A comparison study conducted on a sediment core from a freshwater lake with a known chromium contamination in Muskegon County, MI also shows a good correlation between the methods for transition metals of environmental interest over a wide range of metal concentrations. Total sample preparation and analysis time for the PIXE measurements is roughly one third that of acid digestion and ICP-OES. Also, the acid digestion step does not elute all the metal, while the nondestructive PIXE approach is a total metals analysis method. However the PIXE method generally has higher limits of detection for many environmental metal contaminants. By combining the two techniques, the acid digestion elution factor can be quantified by running PIXE on an original sample and on the residue resulting from acid digestion.     

Study of localised radiation damage to PIPS detectors by a scanning ion microprobe: Measured effects and the consequences for STIM analysis

Radiation damage effects in a PIPS particle detector have been studied by direct irradiation with a 4 MeV He⁺ focused ion beam, using the Eindhoven scanning ion microprobe set-up. This set-up enables extreme sensitivity and accuracy in pulse-height measurement. Pulse-height dependence on ion dose and the lateral variations of pulse-height response after damaging were studied, for different bias voltages. Pulse height was found to decrease linearly with ion dose and this could be observed after only a few ions per scan position, corresponding to a dose of 10⁸/cm². Pulse-height loss was found to be restricted to damaged detector areas. Consequences of this pulse-height dependence on ion dose and scan position for the accuracy of STIM analyses are discussed.     

X-ray microtomography analysis and Molecular Dynamics calculations to understand the dynamic damage process in metals

Dynamic ductile damage has been created by a laser driven shock. The study of these processes consists of predicting it and analysing spatial distributions of pores observed in the target. The challenge is to use the Molecular Dynamics to calculate the propagation of shock waves in ultra thin sheets of metal as well as to compare results with ESRF’s X-ray microtomography.     

Fluid dynamic analysis of a catalytic recombiner to remove hydrogen

Catalytic reacting surfaces in recombiners are a reliable way to remove hydrogen as well as other burnable gases like CO in a passive way from the containment atmosphere of a nuclear power plant (NPP) during an accident. Industrial mature designs are ready to be installed in large dry containments to act as a mitigation measure preferably in the case of severe accidents. Experiments have been carried out to study manifold aspects of recombiners like the efficiency of hydrogen removal, start-up conditions, poisoning, oxygen starvation, steam and water impact and others. Mostly the global behaviour of a given device in a larger environment has been investigated in order to demonstrate the effectiveness and to facilitate the derivation of simplified models for long-term severe accident analyses. There are a number of reasons to look inside a recombiner to understand the interaction of chemistry and flow. This can help in understanding the dependencies of non-measurable variables (e.g. reaction rate), of local surface temperatures and more. It also offers possibilities to increase the chemical efficiency by optimising the geometry properly. Computational fluid dynamics (CFD) codes are available to be used as development tools to include the specifics of catalytic surface reactions. The present paper describes the use of the code system CFX (CFX 4.1 Flow Solver User Guide. 1995, Computational Fluid Dynamics Services, AEA Technology plc, Oxfordshire, UK) for creating a recombiner model. Finally its comparison with existing test data is discussed.     

Molecular dynamic analysis of the structure of dendrimers

We present main results of molecular dynamics simulations that we have carried out in order to investigate structural properties of polyamidoamine (PAMAM) dendrimers. Obtained data confirm the PAMAM dendrimer structure proposed by experiments, performed by means of X-ray scattering (SAXS) and quasi-elastic light scattering (QELS) techniques.     

The quantitative analysis of loop-growth and void-swelling in nickel

Dislocation loop and void growth experiments at several temperatures in the HVEM have been used to investigate point defect behaviour in nickel. It has been found that the dislocation bias is about 5% for interstitials and that voids also have a preference for interstitial defects. The value of the void bias is much less than the dislocation bias, being about 0.5%, so that swelling still occurs. The vacancy migration energy, $\text{E}{}^{\mathrm{v}}{}_{\mathrm{m}}$, has been confirmed to be $\text{1.1 ± 0.1 eV}$.     

Fatigue evaluation of the JT-60 vacuum vessel under the dynamic electromagnetic forces

Fatigue evaluation of the JT-60 vacuum vessel was carried out under the dynamic electromagnetic forces.In the present method, fatigue strength of the vacuum vessel is evaluated not only during the transient response but during the free vibration following the transient response. Stress amplitudes during the transient response are counted using the range-pair count method faithful to the stress strain hysteresis loop. And fatigue damage during the transient response and the free vibration following the transient response is evaluated based on Miner's law.The fatigue evaluation results showed that the JT-60 vacuum vessel has the sufficient fatigue strength and the free vibration has much larger contribution to the fatigue damage than the transient response.     

Nonlinear dynamic analysis of a stacked fuel column subjected to boundary motion

A method has been developed for analyzing the nonlinear dynamic response of a column consisting of stacked elements excited by boundary motions. The elements are constrained by dowel pins which restrict relative horizontal movement but allow vertical and rocking motions between elements. Two different models have been considered. In the first, the dowels are treated as rigid shear connectors, and equations of constraint are used in conjunction with Lagrange multipliers. In the second, the dowels are considered as flexible items. Horizontal slipping at the element-to-element interface is permitted, the Coulomb friction is considered at the contact point. Example problems were solved using both models, and numerical results are presented for the free vibrations of short columns and the boundary-excited response of tall columns.     

Condensation methods for the dynamic analysis of large models

Calculations of the dynamic behaviour of a superstructure including soil-structure interaction with locally discretized models, e.g. using finite elements, lead to large-sized matrices. The order of the matrices may be so high, especially when three-dimensional modelling of soil is required, that rapid loss of accuracy occurs and exceptionally large computer storage and time are needed for calculations. To overcome these problems the order of the models can be reduced to the wanted degrees-of-freedom, for example to those of the superstructure. Condensation methods combined with subsystem modelling lead to models which avoid the calculation disadvantages mentioned above. Some of these methods are discussed and one of them is given preference.This method is based on modal synthesis and reduces the magnitude of the truncation error by using the static parts of the truncated modes without the necessity of their being known.     

An efficient procedure in quantitative analysis using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy has become a general-purpose technique, and internal standard calibration is a common method for quantitative analysis. Calibration models should be reconstructed for different systems and application environments. This study presents an efficient procedure in the construction and selection of calibration models for LIBS analysis. The procedure concludes data preprocess, calibration model construction, and concentration calculation. These steps can be programmed without manual intervention. Results of the quantitative analysis of Ni-based alloys using the proposed procedure are presented in this study.Ten elements are calibrated, and most have an average relative standard error of less than 10%.The proposed procedure is an effective process for constructing and selecting calibration models.     

Numerical techniques for quantitative evaluation of chemical reaction systems with volatile species and their applications to water radiolysis in BWRs

A mass transfer model in boiling flow was proposed for computer simulation of chemical reaction systems. The model can be applied to a wide variety of chemical engineering applications including nuclear reactor plants. A statistical treatment for simple estimation formulae of distribution of chemical reagents in any plant from the simulated results of a specific plant was also proposed.These two mathematical techniques were applied to water radiolysis in BWR primary systems (Oskarshamn-2 and Dresden-2) to evaluate distributions of oxidizing reagents in the systems. Simulated results from the computer program agreed within a 20% error with measured hydrogen and oxygen concentrations. Hydrogen and oxygen concentrations in Dresden-2 estimated by means of the simplified formulae agreed within 26% error with those of the direct simulation results.     

局部喷血分数的计算机定量法

平衡法放射性核素心血管造影局部室壁运动的定性分析有助于对室壁运动异常作出评价。但由于评价结果主要由观察者依据心室舒张末期及收缩末期这二个时相的边界叠加影象来判断,因而主观因素不可避免。特别是对冠心病例,其室壁运动“正常”与“运动低下”之间的鉴别尤为困难,对室间隔的活动也往往难于估价。为此,本文研究了局部室壁运动的计算 平衡法放射性核素心血管造影局部室壁运动的定性分析有助于对室壁运动异常作出评价。但由于评价结果主要由观察者依据心室舒张末期及收缩末期这二个时相的边界叠加影象来判断,因而主观因素不可避免。特别是对冠心病例,其室壁运动“正常”与“运动低下”之间的鉴别尤为困难,对室间隔的活动也往往难于估价。为此,本文研究了局部室壁运动的计算     

A quantitative basis for hair analysis using PIXE

The PIXE technique offers the possibility of scanning a single hair strand longitudinally with a millimetre proton beam for trace elements. However, the accuracy of the method has been questioned since the quantification of the mass concentration has been a serious problem. In this paper a specific beam-hair-detector geometry is assumed, and the correction factor accounting for the proton energy loss and the X-ray absorption in a regular hair is calculated. 43 hair segments from 8 individuals, ranging from 45 to 110 μm in in diameter were analyzed giving a mean value of 4.32% (standard deviation 0.25%) for sulphur, and a mean value of 149 ppm (standard deviation 35 ppm) for zinc. It is shown that the correction is important not only for the determination of the absolute elemental concentrations but also for the determination of their relative longitudinal distributions. The secondary corrections accounting for the inhomogeneous elemental distribution over the cross section and the irregular shape and/or the differing mass density of a hair are also calculated. It is concluded that the accuracy and precision of the PIXE method does not become considerably lower when it is applied to single hair strands, and accuracy and precision below 10% may be reached by implementing the procedure described.     

心肌血流灌注断层定量显像在犬急性心肌梗塞疗效评价中的应用

在１０只犬的实验性心肌梗塞模型上进行心肌断层显像与容积定量分析,对照病理解剖资料评价主要定量参数心肌缺损体积（ＤＶ）及缺损范围分数（ＤＦ）的准确性;另２１只犬分为对照组和Ｎｄ：ＹＡＧ激光心肌血管重建术（ＴＭＲ）组,分别进行实验性心肌梗塞术后心肌断层定量显像。结果表明：病理解剖定量分析获得的心肌梗塞区体积（ＩＶ）与心肌血流断层量结果ＤＶ值具有良好相关（ｒ＝０．８８）,两种方法所计算的心肌病变范围分数     

Nonlinear dynamic analysis of reinforced concrete structures

Dynamic ultimate load calculations mainly for reinforced concrete beams and plates, are discussed. Starting from the corresponding differential equations, the calculations also include the rotational inertia of single beam or plate elements as well as the shear deformations. With actual structural dynamic problems in nuclear power plants, the shear behaviour of reinforced concrete beams and plates is more important than it is usually, as is shown by examples. The finite propagation velocity of bending and shear waves are taken into account. Solution of the equations of motion is obtained by numerical intergration using finite time and space intervals. The calculations are performed using time dependent bending and shear laws for reinforced concrete up to the point of failure with realistic deformations. These latest scientific developments are of great significance for dynamic ultimate load analysis in practice.Elastic-plastic examples of application are compared with corresponding linear-elastic solutions. It is shown that the design of construction members based on elastic-plastic dynamic stress calculations in general is economically advantageous. This important conclusion is proven by numerical results. Also the relation to the approximation of a one-degree-of-freedom dynamic system, including or excluding the plastic ductility of the structural member, is demonstrated.Finally, lumped-mass multi-degree systems calculated by integrating numerically the corresponding equations of motion, are dealt with briefly. A nonlinear dynamic calculation of a foundation of a recently built reactor building is presented as an example for blast resistant analysis.     

Finite element analysis of experiment on dynamic behavior of cylinder due to electromagnetic force

An experiment on the dynamic behavior of a cylinder resulting from a transient electromagnetic force was conducted. This experiment can be considered associated with the dynamic deformation of a first wall or a vecuum vessel of a controlled thermonuclear tokamak type reactor. The dynamic strain of the cylinder was measured under a transient strong magnetic field using a non-inductive strain gage and a shielding room. A finite element method was applied to the analysis of the experiment by solving Maxwell's equations and the equation of motion of the cylinder simultaneously. The numerical results are in good agreement with the experimental results.     

Portable fiber-optic laser-induced breakdown spectroscopy system for the quantitative analysis of minor elements in steel

In this paper, we developed a portable laser-induced breakdown spectroscopy(LIBS) using an optical fiber to deliver laser energy and used it to quantitatively analyze minor elements in steel.The R~2 factors of calibration curves of elements Mn, Ti, V, and Cr in pig iron were 0.9965,0.9983, 0.9963, and 0.991, respectively, and their root mean square errors of cross-validation were 0.0501, 0.0054, 0.0205, and 0.0245 wt%, respectively. Six test samples were used for the validation of the performance of the calibration curves established by the portable LIBS. The average relative errors of elements Mn, Ti, V, and Cr were 2.5%, 11.7%, 13.0%, and 5.6%,respectively. These results were comparable with most results reported in traditional LIBS in steel or other matrices. However, the portable LIBS is flexible, compact, and robust, providing a promising prospect in industrial application.