Particle induced X-ray emission (PIXE) analyses on metal samples with structured surfaces

The X-ray yields obtained in PIXE measurements from metal samples with bent or relief surface have been investigated experimentally and by a computer simulation. It was found, that in the fundamental parameter method correct analytical results will be obtained, if two conditions are fulfilled: (1) the inclination of the tangential plane of the bent surface at the point where the ion beam hits this surface has to be known; and (2) the radius of curvature of the surface structure must be larger than 3 to 4 times the ion beam radius used.     

The Influence of Silicon Surface Defects on MOS Radiation-Sensitivity

The relationships of the electrical properties of irradiated MOS structures to processed-induced surface defects have been investigated. It has been found that the radiation-induced perturbations in oxide space-charge and interface states relate directly to the density of oxidation-induced stacking faults and edge dislocations. The density of such surface defects depends on both the structural properties of the starting silicon and the fabrication procedures. Oxidation-induced stacking faults are strongly related to the oxidation conditions, such as temperature, time, and ambiance. High-frequency CV, quasi-static CV, and ac conductance techniques were used to determine the interface state densities and flat-band voltage distributions. It has been found that, in addition to interface states, exposure to ionizing radiation causes gross non-uniformities in trapped positive space-charge. Using secondary ion mass spectrometry (SIMS) on an MOS sample possessing a high density of stacking faults, it has been shown that positive charge-species drift to the SiO2/Si interface and form clusters in a random fashion similar to that of the defects delineated by differential etching. Based on the known relationship of surface generation lifetime on surface defects pre-irradiation lifetime has been demonstrated as an effective electrical parameter for the prediction of the total-dose radiation sensitivity of MOS devices.     

The veining phenomenon in unalloyed plutonium

An investigation has been made of the veining phenomenon in unalloyed plutonium. The surface markings, or veins, which are sometimes seen on α-phase plutonium samples, arise as a result of the β → α transformation. As far as is known, this veining is unrivalled in its scale and form as compared with the solid state surface transformation effects shown by any other metal. The phenomenon has been explained by the application of the Le Chatelier principle to the phase change. In this instance, the large (10%) volume contraction associated with the β → α reaction and the anisotropy of the monoclinic α-phase structure, account for the fact that the veins are so prominent in plutonium. On the basis of the proposed model, the veins can only form at temperatures where the transformation mechanism is non-martensitic.     

Trapping of energetic hydrogen ions in reactive metals

A model is proposed to describe the trapping of a beam of energetic ions of hydrogen isotopes by targets of reactive metals in which the incident ions dissolve exothermically. The model considers the ions free to diffuse inside the metal, and to escape from the surface at a rate determined from the known solubility data.It has been shown that in the case of semi-infinite geometry the trapping efficiency can be expressed in analytic form as a function of dose. However, in the two dimensional case appropriate for beam experiments, radial diffusion becomes important and a numerical solution has been found to be necessary. The model has been compared with experimental results on the trapping of 18 keV deuterons by targets of Nb, Zr, Ti and Pd in the temperature range 230–1000 K and in general good agreement has been obtained.     

Post-dryout heat transfer: Physical mechanisms and a survey of prediction methods

Significant thermal non-equilibrium has been observed in the post-dryout regime. The degree of thermal non-equilibrium depends primarily on liquid-vapor interaction, and the heated surface temperature is controlled by the near-wall vapor velocity, vapor superheat and liquid-wall interaction. The possible mechanisms of post-dryout heat transfer and the state of the art for predicting post-dryout temperatures are described. The semi-theoretical approach is the most promising for simple geometries. Four empirical methods of predicting post-dryout temperatures are discussed. A bibliography and a table of all known post-dryout heat transfer correlations are presented.     

硅离子注入聚合物摩擦特性研究

采用金属蒸汽真空弧（MEVVA）离子注入机引出的Si离子进行了聚酯薄膜（PET）改性研究，注入后的聚酯膜表面结构发生了很大的变化。用透射电子显微镜观察了注入聚酯膜的横截面，结果表明，在注入层形成颗粒的沉积。红外吸收测量揭示这些颗粒为SiC和富集的碳颗粒。这些颗粒增强了注入层表面强化效果。用纳米硬度计测量显示，Si离子注入可明显地提高聚酯膜表面硬度和杨氏模量，从而极大地的增强了表面抗磨损特性。最后讨论了Si离子注入聚酯膜改善特性的机理。     

离子注入玻璃

离子注入和离子束分析技术在半导体和金属改性中已获得广泛应用,近年来又开始应用于绝缘体。在1981年第一届绝缘体辐照效应国际会议(REI-81)上,美国Sandia实验室Arnold和意大利Chinellato等发表离子注入玻璃效应的初步研究。Mazzoldi曾应用核反应分析对玻璃辐照效应进行了详细研究。 带电粒子辐照玻璃引起网状损伤并改变了表面化学成分。钠玻璃经离子注入后产生钠离子迁移,Na迁移有两种不同机构,在低质量离子辐照时以电子阻止本领为主,此时钠受到和     

The study on a statistical methodology for PWR fuel rod internal pressure evaluation

The most limiting design criteria for high Burnup PWR fuel are known to be rod internal pressure and cladding oxidation. Some fuel vendors have been increasing the design margin of rod internal pressure by increasing fuel rod plenum volume or optimizing fuel pellet grain size. In this study, a sophisticated statistical methodology that employs the response surface method and Monte Carlo simulation has been proposed to increase the design margin of rod internal pressure and subsequently a simplified statistical methodology has been developed to simplify the sophisticated statistical methodology. The simplified statistical methodology utilizes the system moment method combined with a deterministic approach for calculating a maximum variance of rod internal pressure. This simplified statistical methodology may be more efficient in the reload core fuel rod performance analyses than the sophisticated statistical methodology since the former eliminates numerous calculations needed for the evaluation of power history-dependent variances. It is found that this simplified methodology also generates more conservative rod internal pressure than the typical statistical methodology.     

Mn DEPLETION IN THE SURFACE LAYER OF STAINLESS STEEL 304 LN AT THE TEMPERATURE 1200 K

The Mn component of stainless steel 304 LN has been found to be severely depleted in the surface layer during heating at the temperature 1200 K. The surface concentrations of Mn were reduced by about 2- 3 orders of magnitude in comparison with the bulk value, as was revealed by a secondary ion mass spectroscopy (SIMS) system. And the Mn concentration gradient in the surface layer was examined, too, by SIMS. Massive preferential losses of Mn have been determined by using the catcher technique and proton induced X- ray emission (PIXE). A theoretical model has been proposed for calculating the surface concentration changes for a component in an alloy under heating. A comparison shows a good agreement between the calculation and experimental results from SIMS and catcher technique.     

PIXE analysis of Zn enzymes

Zinc is a necessary component in the action and structural stability of many enzymes. Some of them are well characterized, but in others, Zn stoichiometry and its association is not known. PIXE has been proven to be a suitable technique for analyzing metallic proteins embedded in electrophoresis gels. In this study, PIXE has been used to investigate the Zn content of enzymes that are known to carry Zn atoms. These include the carbonic anhydrase, an enzyme well characterized by other methods and the cytoplasmic pyrophosphatase of Rhodospirillum rubrum that is known to require Zn to be stable but not how many metal ions are involved or how they are bound to the enzyme. Native proteins have been purified by polyacrylamide gel electrophoresis and direct identification and quantification of Zn in the gel bands was performed with an external proton beam of 3.7 MeV energy.     

Silicon Surface Barrier Detector

A method has been established for producing silicon surface barrier detectors having an energy resolution of 0.7% for 5.3 MeV α particles, and which are stable for long periods of time. The fabricated detector has been proved to possess a depletion layer as thick as 200 μ and a surface layer with energy loss less than 15 keV for 5.3 MeV α particles. The stability of the detector was also tested and it was found to be stable for at least 2–3 months.     

Radiation-assisted phosphorous diffused polyimide as low thermal emissivity material

Radiation enhanced diffusion of phosphorous into the surface layer of polyimide is shown to be effective in lowering its thermal emissivity in the range of wavelengths between 8 and 14 μm. The effect of the fluence of irradiation on the value of emittance has been studied and lowest emissivity was associated with the formation of nanoclusters on the surface. The variation in the dielectric constant of the irradiated polyimide has been monitored as a function of irradiation. Increase in the value of dielectric constant is correlated to the corresponding value of the thermal emittance. Semiempirical calculations, using Fresnel’s relation, are used to validate the measurements. Elemental concentration of phosphorous in the surface region of the film and its morphology has been studied by energy dispersive X-ray analysis using scanning electron microscope.     

离子注入对超高分子聚乙烯磨损性能的影响

用８０ｋｅＶ不同剂量的Ｃ３Ｈ＾＋８,Ｎ＾＋２对超高分子聚乙烯样品进行离子注入,通过反冲探测分析表明注入层Ｈ含量的变化,对样品表面在离子注入前后的磨损性能进行了测试。实验结果显示,离子注入以后样品表面氢含量减少,磨损性能增强。     

Experimental Study on Material Surface Modification of Tool Steel

This paper presents the surface temperature behavior of M42 high-speed tool steel samples during N^ implantation in an industrialized GLZ-100 metal-ion implantation machine.A detail study has been made on the parameters of N^ implantation.Optimized technical parameters have been preseted.The microhardness of the sample surface implanted under these parameters has been increased by a factor of 2.3.and the wear-resistance has been improved by about 5.4 times.The research on the mechanism of surface modification of M42 steel by nitrogen ion implantation has also been made.     

特定探测器计算模型符合方法研究

特定探测器探头的物理尺寸一般是已知的,但是生产商对一些涉及到探测器性能的尺寸是保密的,诸如探测器的孔径、井深及死层,由此给模拟计算带来了困难。文章通过蒙特卡罗方法建立了均匀分布的面源以及源粒子各向同性运动的抽样方法;计算了Eu152面源与探测器在一定距离的γ射线响应能谱,使用计算结果与相同条件下实验结果的相对效率符合法和能谱相似度符合法校验,并修正探测器模型,从而为确定探测器的计算模型,进一步计算探测器的效率和能谱计算奠定了基础。     

Optimisation of hot isostatic pressing bonded SS/SS joints conditions for ITER blanket shield

In the engineering design activity of international thermonuclear experimental reactor (ITER), stainless steels are being considered as candidates materials for several module type structures. Hot isostatic pressing (HIP) technique is expected for the fabrication of these modules. Stainless steel powders are simultaneously consolidated as mono-material block or/and joined in bi-material module.This paper reviews the manufacturing stages, non-destructive examination and the developments of the HIP bonded joints of 316L SS (powder and solid) for application to the ITER shield blanket.It is well known that the powder surface oxidation negatively influences the impact toughness of raw material and joints consolidated by this way. In order to get acceptable mechanical properties of materials, a study on the effect of reducing the powder oxygen content has been launched. To evaluate susceptibility to the oxygen content of HIPed joint specimens, tensile and toughness tests have been performed.From this study, optimal conditions of HIP were fitted and the influence of oxygen was mastered to obtain good mechanical properties of the consolidated powder material as well as for HIPed junction.     

Stable crack growth of axial flaws in pressure vessels

The ductile crack growth of axial through and part-through cracks in a vessel under internal pressure has been studied experimentally to contribute to the fundamental problem whether or not and under which conditions resistance curves obtained from specimens can be transferred to large scale components. The experiments and numerical analyses are part of a research program on fracture mechanics failure concepts for the safety assessment of nuclear components.Whereas only an averaged crack extension is determined in specimen tests, the local propagation of cracks may be of main importance for surface cracks in vessels and pipes. In the present experiments, the surface cracks revealed the well known canoe shape, i.e. a larger crack extension has occurred in the axial direction than in the wall thickness direction. Two of these tests have been analysed by finite element calculations to obtain the variation of the J-integral along the crack front and the stress and strain state in the vicinity of the crack. The local crack resistance appeared to depend on the local stress state. To Predict ductile crack extension correctly, J_R-curves have to account for the varying triaxiality of the stress state along the crack front.     

Reliability assessment of passive containment isolation system using APSRA methodology

In this paper, a methodology known as APSRA (Assessment of Passive System ReliAbility) has been employed for evaluation of the reliability of passive systems. The methodology has been applied to the passive containment isolation system (PCIS) of the Indian advanced heavy water reactor (AHWR). In the APSRA methodology, the passive system reliability evaluation is based on the failure probability of the system to carryout the desired function. The methodology first determines the operational characteristics of the system and the failure conditions by assigning a predetermined failure criterion. The failure surface is predicted using a best estimate code considering deviations of the operating parameters from their nominal states, which affect the PCIS performance. APSRA proposes to compare the code predictions with the test data to generate the uncertainties on the failure parameter prediction, which is later considered in the code for accurate prediction of failure surface of the system. Once the failure surface of the system is predicted, the cause of failure is examined through root diagnosis, which occurs mainly due to failure of mechanical components. The failure probability of these components is evaluated through a classical PSA treatment using the generic data. The reliability of the PCIS is evaluated from the probability of availability of the components for the success of the passive containment isolation system.     

Nuclear Data Sheets for A = 161

Nuclear data based on the available experimental information on A = 161 nuclides are presented.All nuclides with 64 ? Z ? 72 for this A-value are known. The 4.2-m Z = 70 (Yb) isobar has been reported only recently; this activity was assigned earlier to A = 160. An isomer in ¹⁶¹Lu is known; however, nothing is known about its ground state. It is also not certain if the 17-s state in ¹⁶¹Hf is indeed its ground state.In the following pages, the level properties, spin assignments, comments and gamma-ray properties precede the experimental data for each nuclide.It has been attempted to include all data prior to July 31, 1974. Some of the older data have been omitted or referenced as “other measurements.” Unless indicated otherwise, all energies are in keV.     

关于表面放射性物质污染标准的讨论

本文综合了英法等一些国家和 IAEA 推荐的表面放射性物质污染标准,并与我国标准进行了比较。在理论计算和现场调查基础上,讨论了我国现行表面污染标准中存在的问题,并提出了具体建议。