Total reflection X-ray spectroscopy as a rapid analytical method for uranium determination in drainage water

Uranium concentrations in drainage water are typically determined by α-spectrometry. However, due to the low specific radioactivity of uranium, the evaporation of large volumes of drainage water, followed by several hours of measurements, is required. Thus, the development of a rapid and simple detection method for uranium in drainage water would enhance the operation efficiency of radiation control workers. We herein propose a novel methodology based on total reflection X-ray fluorescence (TXRF) for the measurement of uranium in contaminated water. TXRF is a particularly desirable method for the rapid and simple evaluation of uranium in contaminated water, as chemical pretreatment of the sample solution is not necessary, measurement times are typically several seconds, and the required sample volume is low. We herein employed sample solutions containing several different concentrations of uranyl acetate with yttrium as an internal standard. The solutions were placed onto sample holders, and were dried prior to TXRF measurements. The relative intensity, otherwise defined as the net intensity ratio of the Lα peak of uranium to the Kα peak of yttrium, was directly proportional to the uranium concentration. Using this method, a TXRF detection limit for uranium in contaminated water of 0.30 µg/g was achieved.     

A method for thickness determination of thin films of amalgamable metals by total-reflection X-ray fluorescence

A method for thickness determination of thin amalgamable metallic films by total-reflection X-ray fluorescence (TXRF) is presented. The peak’s intensity in TXRF spectra are directly related to the surface density of the sample, i.e. to its thickness in a homogeneous film. Performing a traditional TXRF analysis on a thin film of an amalgamated metal, and determining the relative peak intensity of a specific metal line, the layer thickness can be precisely obtained. In the case of gold thickness determination, mercury and gold peaks overlap, hence we have developed a general data processing scheme to achieve the most precise results.     

全反射X射线荧光光谱法测定核废水中的铀和钍

建立了直接制样-全反射X射线荧光光谱法(TXRF)测定核废水中U、Th元素.以Ga做内标,方法的检出限分别为0.010、0.008 mg/L,标准溶液测量结果相对标准偏差小于7％(n=6),加标回收率在95％?115％之间.通过TXRF法与电感耦合等离子体质谱法(ICP-MS)对未知样品的测量结果比较,两种方法测量结果...     

全反射X荧光分析技术的应用

简要地介绍了全反射Ｘ荧光分析技术和一台小型全反射Ｘ荧光分析装置，这台装置的最低检出限对于Ｃｏ元素和Ｃｕ靶Ｘ光管激发下是７ｐｇ，对Ｓｒ元素，Ｍｏ靶是３０ｐｇ，对自来水、海洋动物、头发等进行了应用分析实验。     

PIXE analysis of high Z complex matrices

The study of complex materials (nonhomogeneous matrices containing medium and/or heavy atoms as major elements) by PIXE requires the tailoring of the experimental set up to take into account the high X-ray intensity produced by these main elements present at the surface, as well as the expected low intensity from other elements “buried” in the substrate. The determination of traces is therefore limited and the minimum detection limit is generally lower by at least two orders of magnitude in comparison with those achievable for low Z matrices (Z20). Additionally, those high Z matrices having a high absorption capability, are not always homogeneous. The nonhomogeneity may be, on the one hand, a layered structure (which is uneasy to profile by RBS if the material contains elements of neighbouring masses or if the layered structure extends on several microns) or, on the other hand, inclusions which are to be localized. PIXE measurements at various incident energies (and with various projectiles (p, d, He³, He⁴)) are then an alternative method to overcome those difficulties. The use of special filters to selectively decrease the intensity of the most intense X-ray lines, the accurate calculation of the characteristic X-ray intensity ratios (K/Kβ, L/Lβ) of individual elements, the computation of the secondary X-ray fluorescence induced in thick targets are amongst the most important parameters to be investigated in order to solve these difficult analytical problems. Examples of Cr, Fe, Ni, Cu, Ag and Au based alloys with various coatings as encountered in industrial and archaeological metallurgy are discussed. RBS, PIGE and NRA are sometimes simultaneously necessary as complementary (or basic) approaches to identify corroded surface layers.     

上海光源BL15U1束线的SRXRF定量分析

本文介绍了用于同步辐射X射线荧光(XRF)定量分析的基本参数法(FP)和MC模拟法。上海光源(SSRF)硬X射线微聚焦光束线(BL15U1)应用上述两种方法对样品进行定量分析,验证了方法的有效性并用定量分析结果计算了BL15U1光束线部分元素的荧光探测限。实验结果表明,对样品中μg/g量级元素含量的定量分析结果相对误差都在10%以内,而使用MC模拟法可以直观地比较不同参数下的模拟谱与实验谱,辅助实验参数的确定,从而减小参数引起的误差,得到更为准确的结果。此外,对BL15U1探测限的计算表明该光束线具备开展高性能荧光实验的能力。     

X射线编码孔成像技术在近地太空核爆探测中的应用

根据X射线编码孔成像的原理,搭建了地面模拟成像系统,在此基础上建立了编码孔成像技术探测近地太空核爆当量和方位的理论计算方法,获得了系统响应（灰度）与X射线强度、重建图像质心位置与X射线入射角度之间的关系,并开展了核爆当量和方位的模拟探测实验,对实验数据和理论计算数据进行了对比和分析。结果表明,理论计算结果与实验结果吻合较好,验证了采用X射线编码孔成像技术探测近地太空核爆的可行性,同时证明X射线编码孔成像具有较多针孔成像更高的探测灵敏度、信噪比和抗干扰能力。     

An industrial SR TXRF facility at ESRF

A TXRF industrial facility for the mapping of trace impurities on the surface of 300 mm Silicon wafers is presently under construction at the ESRF, European Synchrotron Radiation Facility, in Grenoble (France) and its commissioning phase will start at the end of 1998. The elements to be detected range from Na to Hg with a target routine detection limit of 10⁸ atoms /cm². The facility is the result of a collaboration between the ESRF and some of the major European semiconductor companies in the framework of the MEDEA consortium. Preliminary experiments at ESRF reached a detection limit of 1.7 × 10⁸ for Ni atoms (17 fg) in not optimised experimental conditions. The facility will improve the detection limit by a factor of 50. However, this gain in sensitivity will be traded in the possibility of mapping the surface of 300 mm wafer with a resolution of 500 pixels and a throughput of three wafers/h.     

2 keV He and Ne ion scattering on a Cu(110) surface: Experiment vs simulation

Scattering experiments performed at 143° with a TOF-ISS system on a Cu(110) single crystal indicate the very different sampling depth of He ions as compared with Ne ions. The ISS polar scans measured with He ions show a high sensitivity to the bulk atomic rows of the single crystal, whereas the scans measured with Ne ions indicate a sensitivity to only a couple of atoms in the first atomic layers. In order to evaluate the depth sampled by the backscattered particles, ion trajectories have been calculated with the MARLOWE simulation code. With Ne, the simulation shows that backscattered particles arise only from the 4 first layers (5 Å), but with He ions, they come from at least 80 layers (100 Å). A detailed analysis of escaping trajectories indicates that the Ne projectiles are scattered from the first layers after short trajectories. On the other hand, helium trajectories are usually quite complex, due to the possibility to follow privileged directions (channels), so that the projectiles can scatter from deep layers. We see that, even at low energy, channeling may be the major contributor to the variations of the backscattered intensity.     

On neutron phase contrast imaging

Improving the spatial resolution conditions in a neutron imaging experiment enables the detection of phase-based contrast in addition to attenuation contrast. Addressing not only the amplitude but also the phase of radiation in an imaging experiment allows for obtaining additional information about the sample. The so-called neutron phase contrast method improves imaging results mainly by edge enhancement which increases the visibility of sub-resolution structures and of low attenuation contrast materials. These effects have been found at high intensity synchrotron X-ray sources before and have been applied to neutron imaging recently. However, the excellent coherence conditions and spatial resolution of imaging instruments at state-of-the-art synchrotron sources can hardly be compared to neutron imaging. Nevertheless, edge enhancement has been found for increased resolution (coherence) conditions in neutron experiments as well. As for X-ray instruments the effects have been explained by diffraction, although typical interference fringes have never been recorded. In contrast this article will explain the effects measured with neutron radiation by refraction and total reflection. Both of these do not require high spatial coherence. Therefore improved resolution and not increased coherence will be considered as precondition to obtain the reported signals and to understand the results. Considerations concerning relaxed collimation requirements for improved detector resolutions will be presented as a consequence.     

Smaller & Sooner: Exploiting High Magnetic Fields from New Superconductors for a More Attractive Fusion Energy Development Path

The current fusion energy development path, based on large volume moderate magnetic B field devices is proving to be slow and expensive. A modest development effort in exploiting new superconductor magnet technology development, and accompanying plasma physics research at high-B, could open up a viable and attractive path for fusion energy development. This path would feature smaller volume, fusion capable devices that could be built more quickly than low-to-moderate field designs based on conventional superconductors. Fusion’s worldwide development could be accelerated by using several small, flexible devices rather than relying solely on a single, very large device. These would be used to obtain the acknowledged science and technology knowledge necessary for fusion energy beyond achievement of high gain. Such a scenario would also permit the testing of multiple confinement configurations while distributing technical and scientific risk among smaller devices. Higher field and small size also allows operation away from well-known operational limits for plasma pressure, density and current. The advantages of this path have been long recognized—earlier US plans for burning plasma experiments (compact ignition tokamak, burning plasma experiment, fusion ignition research experiment) featured compact high-field designs, but these were necessarily pulsed due to the use of copper coils. Underpinning this new approach is the recent industrial maturity of high-temperature, high-field superconductor tapes that would offer a truly “game changing” opportunity for magnetic fusion when developed into large-scale coils. The superconductor tape form and higher operating temperatures also open up the possibility of demountable superconducting magnets in a fusion system, providing a modularity that vastly improves simplicity in the construction, maintenance, and upgrade of the coils and the internal nuclear engineering components required for fusion’s development. Our conclusion is that while tradeoffs exist in design choices, for example coil, cost and stress limits versus size, the potential physics and technology advantages of high-field superconductors are attractive and they should be vigorously pursued for magnetic fusion’s development.     

Scanning X-ray microfluorescence in a SEM for the analysis of very thin overlayers

In this paper, we used back-foil scanning X-ray microfluorescence (SXRF) and we examined the sensitivity of the technique for the analysis of very thin overlayers, where electron probe X-ray microanalysis (EPMA) reaches its detection limits. The lateral resolution of back-foil SXRF is also calculated for all the systems used. Both experimental results and Monte-Carlo calculations are used in this respect. Back-foil SXRF used in optimized experimental conditions, is found to be more sensitive than EPMA, especially in the case of very thin overlayers. The lateral resolution of back-foil SXRF is of the order of some micrometers. This is much better than the lateral resolution in conventional XRF and of the same order of magnitude as in EPMA.     

Tests for “cold fusion” in the Pd-D2 and Ti-D2 systems at 40–380 MPa and −196-27°C

Experiments have been conducted on the Pd-D₂ and Ti-D₂ systems at 40–380 MPa and −196-27°C to investigate the possibility that “cold fusion” occurs in palladium and titanium deuterides generated by reaction with high-pressure D₂ gas. The experiments were performed using a 4.8 mm i.d. stainless steel pressure vessel that can be operated routinely at pressures as high as 400 MPa. In experiments completed to date, reactions between high-purity Pd or Ti and D₂ were monitored with: (1) an array of three BF₃ neutron detectors, (2) an internal, type-K sample thermocouple, and (3) an internal, type-K reference thermocouple located approximately 10 cm above the sample thermocouple. Using a²⁵²Cf source, the efficiency of the BF₃ detector array was determined to be approximately 6%. During experimentation, the three neutron detectors were immersed in a water bath thermostated at 27°C. The neutron count rate, D₂ pressure, sample and reference thermocouple readings, and bath temperature were recorded continuously at time intervals ranging from 6 seconds to 10 minutes. Experimental results obtained so far range from negative to potentially significant. No sustained heat production has been observed in any experiment. Thermal pulses that persist briefly after pressurizing Pd with D₂ gas are attributable to small amounts of chemical heat released when Pd and D₂ react to form palladium deuteride. No sustained neutron flux above background was observed in any Pd-D₂ experiment. On the other hand, in a Ti-D₂ experiment just completed, potentially significant results were obtained. During this experiment, there was a period of 5 consecutive hours when count rates rose to approximately 60 counts/hour above the average background rate. This detector count rate corresponds nominally to 1000 neutrons/hour emitted from the Ti-D₂ sample. However, due to several deficiencies in our neutron detection methods and equipment, we cannot demonstrate conclusively that our experimental data are valid. Consequently, we are upgrading our neutron detection equipment in preparation for a second, improved Ti-D₂ experiment.     

White beam synchrotron topography using a high resolution digital X-ray imaging detector

X-ray topography is a well known imaging technique to characterise strain and extended defects in single crystals. Topographs are typically collected on X-ray films. On the one hand such photographic films show a limited dynamic range and the production of films will be discontinued step by step in the near future. On the other hand new imaging detectors improved for X-ray tomography become more and more attractive even for topography because of increasing resolution, dynamic range, speed and active area. In this paper we report about the upgrade of the TOPO-TOMO beamline at the synchrotron light source ANKA, Research Centre Karlsruhe, with a high resolution digital camera for the topography use.     

Efficient Isotope Ratio Analysis of Uranium Particles in Swipe Samples by Total-Reflection X-ray Fluorescence Spectrometry and Secondary Ion Mass Spectrometry

A new particle recovery method and a sensitive screening method were developed for subsequent isotope ratio analysis of uranium particles in safeguards swipe samples. The particles in the swipe sample were recovered onto a carrier by means of vacuum suction-impact collection method. When grease coating was applied to the carrier, the recovery efficiency was improved to 48±9%, which is superior to that of conventionally-used ultrasoneration method. Prior to isotope ratio analysis with secondary ion mass spectrometry (SIMS), total reflection X-ray fluorescence spectrometry (TXRF) was applied to screen the sample for the presence of uranium particles. By the use of Si carriers in TXRF analysis, the detection limit of 22 pg was achieved for uranium. By combining these methods with SIMS, the isotope ratios of ²³⁵U/²³⁸U for individual uranium particles were efficiently determined.     

Post-irradiation examination of a fuel pin using a microscopic X-ray system: Measurement of carbon deposition and pin metrology

The paper presents some interesting aspects associated with X-ray imaging and its potential application in the nuclear industry. The feasibility of using X-ray technology for the post-irradiation examination of a fuel pin has been explored, more specifically pin metrology and carbon deposition measurement. The non-active sample was specially designed to mimic the structure of an AGR fuel pin whilst a carbon based material was applied to the mock up fuel rod in order to mimic carbon deposition. Short duration low energy (50 kV) 2D digital radiography was employed and provided encouraging results (with respect to carbon deposition thickness and structure measurements) for the mock up fuel pin with a spatial resolution of around 10 μm. Obtaining quantitative data from the resultant images is the principal added value associated with X-ray imaging. A higher intensity X-ray beam (90 kV) was also used in conjunction with the low energy set-up to produce a clear picture of the cladding as well as the interface between the lead (Pb mimics the uranium oxide) and stainless steel cladding. Spent fuel metrology and routine radiography are two additional tasks that X-ray imaging could perform for the post-irradiation examination programme. Therefore, when compared to other techniques developed to deliver information on one particular parameter, X-ray imaging offers the possibility to extract useful information on a range of parameters.     

Heavy Metal Detection in Soils by Laser Induced Breakdown Spectroscopy Using Hemispherical Spatial Confinement

Spatial confinement has great potential for Laser Induced Breakdown Spectroscopy(LIBS) instruments after it has been proven that it has the ability to enhance the LIBS signal strength and repeatability.In order to achieve in-situ measurement of heavy metals in farmland soils by LIBS,a hemispherical spatial confinement device is designed and used to collect plasma spectra,in which the optical fibers directly collect the breakdown spectroscopy of the soil samples.This device could effectively increase the stability of the spectrum intensity of soil.It also has other advantages,such as ease of installation,and its small and compact size.The relationship between the spectrum intensity and the laser pulse energy is studied for this device.It is found that the breakdown threshold is 160 cm~(-2),and when the laser fluence increases to 250 J/cm~2,the spectrum intensity reaches its maximum.Four different kinds of laser pulse energy were set up and in each case the limits of detection of Cd,Cu,Ni,Pb and Zn were calculated.The results show that when the laser pulse fluence was 2.12 GW/cm~2,we obtained the smallest limits of detection of these heavy metals,which are all under 10 mg/kg.This device can satisfy the needs of heavy metal in-situ detection,and in the next step it will be integrated into a portable LIBS instrument.     

In-situ high-energy-resolution X-ray absorption spectroscopy for UO2 oxidation at SSRF

Based on the high-energy-resolution fluorescence spectrometer on the BL14W1 beamline at Shanghai Synchrotron Radiation Facility,an in-situ high-energyresolution X-ray absorption spectroscopy technique,with an in-situ heating cell,was developed.The high-energyresolution fluorescence detection for X-ray absorption near-edge spectroscopy (HERFD-XANES) was tested in a UO2 oxidation experiment to measure the U L3-edge,with higher signal-to-noise ratio and higher-energy-resolution than conventional XANES.The technique has potential application for in-situ study of uranium-based materials.