Determination of sulphur and copper depth distribution in patina layers using nuclear reaction techniques

A method for Cu and S profiling in patina layers was developed by applying a combination of nuclear reaction analysis (NRA) and Rutherford backscattering spectroscopy (RBS). The copper profiling was performed by using the 1327 keV γ-ray deexciting the third excited state to the ground state of ⁶³Cu produced by the reaction ⁶³Cu(p,p^′γ)⁶³Cu. For the determination of sulphur the 2230 keV γ-ray was used deexciting the first excited state to the ground state of ³²S formed through the reaction ³²S(p,p^′γ)³²S, which exhibits three sharp resonances at projectile energies 3.094, 3.195 and 3.379 MeV. The relevant cross-sections were measured in the energy range between 3.0 and 3.7 MeV in steps of 20 keV at 125° to the incident proton beam direction. The technique was tested using artificially produced and natural copper patina layers. Supporting information on the depth distribution of the constituent elements of the patina samples was obtained by p-RBS (E_p: 1.5 MeV, θ: 160°).     

Study of nuclear reaction method for the determination of protein content in wheat seeds

A 13.4 MeV deuteron beam from the 1.2 meter cyclotron of Sichuan University was used to determine the protein content in wheat seeds on the basis of （d,p） reactions. The influence of the variation of the water content in seeds has been investigated.     

铀表面钛镀层原位氧化行为的AES和EELS研究

利用铀的电子能量损失谱(EELS)、俄歇电子能谱(AES)原位．研究了在室温下O2气氛中表面Ti膜初始氧化过程中表面结构的变化。结果表明，Ti膜的氧化速度比金属Ti更快；Ti膜氧化时与金属Ti一样可形成Ti(固溶O)、TiO、Ti2O3、TiO2．氧化物以岛状形式生长，并以多种氧化态并存；其氧化过程为Ti→Ti(固溶O)→TiO→Ti2O3→TiO2。     

Real-time measurement of implanted deuterons by using the nuclear reaction H(d,p)H

We propose a method for real-time measurement of the density of implanted deuterons in solid materials during deuterium implantation. In this method, the density of implanted deuterons is measured by detecting the emitted protons from the deuteron fusion reaction between the incident deuterons and the implanted deuterons. A negative deuterium beam with an energy of 90 keV is used both for the implanted atoms and a probe beam to measure the implanted deuterons. The density of the implanted deuterium atoms was observed to be drastically different between the single crystal and poly-crystal in Ta.     

Study of the MTC estimation by noise analysis in 2-D heterogeneous systems

The effect of a heterogeneous distribution of the temperature noise on the MTC estimation by noise analysis is investigated. This investigation relies on 2-group diffusion theory, and all the calculations are performed in a 2-D realistic heterogeneous core. It is shown, similarly to the 1-D case, that the main reason of the MTC underestimation by noise analysis compared to its design-predicted value lies with the fact that the temperature noise might not be homogeneous in the core, and therefore using the local temperature noise in the MTC noise estimation gives erroneous results. A new MTC estimator, which was previously proposed for 1-D 1-group homogeneous cases and which is able to take this heterogeneity into account, was extended to 2-D 2-group heterogeneous cases. It was proven that this new estimator is always able to give a correct MTC estimation with an accuracy of 3%. This small discrepancy comes from the fact that the reactor does not behave in a point-kinetic way, contrary to the assumptions used in the noise estimators. This discrepancy is however quite small.     

Nucleation and growth of defect clusters in CeO2 irradiated with electrons

Nucleation and growth process of defect clusters in cerium dioxide (CeO₂) with fluorite-type crystal structure has been investigated in situ under electron irradiation by using high voltage transmission electron microscopy. Planar defect clusters were formed with electron irradiation ranging from 200 to 1000 keV at temperatures below 450 K. The defect clusters were determined to be faulted-interstitial type dislocation loops lying on {1 1 1} planes. The growth rate of dislocation loops was found to increase with decreasing electron energy. An analysis of the fluence dependence of the growth process of dislocation loops suggests an increase in the vacancy mobility with decreasing electron energy. The rate of the electronic excitation is discussed in terms of the radiation-induced diffusion of oxygen-ion vacancies.     

Al_2O_3样品制备技术及~(26)Al的AMS测量

报道了用于加速器质谱计2 6 Al分析的Al2 O3的制备流程及2 6 Al的测量过程。制备的空白样品2 6 Al/ 2 7Al比值 <10 - 13,显示出同量异位素2 6 Mg干扰小。制备流程是成功的。     

Coexistance of C40 and C54 TiSi2 during the solid state reaction of Ti/Mo/Si system

1 INTRODUCTIONThe so called "fine hoe effect" would raise the temPerature of the C54 TiSi2 fOrma-tion in subdricron Si line (<0.5 pm), in which the density of nucleaton sites is lower tha1lthat in bulk Si material. It was well establlshed[1~5J that the introduction of refTactoTymetals (RMs) such as Mo, Ta, Nb, W into Ti-Si system can ellminate such "fine line effect" of C54 TiSi= fOrmation by reducing the formation temperature of C54 TiSi? phaseby 100- 150' C. However, the mecha…     

Microstructural study of an irradiated high-nickel alloy by X-ray line profile analysis and TEM observations

The microstructure was investigated in previously deformed specimens of a high-nickel alloy with four levels of initial dislocation density, both before and after irradiation in BOR-60 reactor at 370–400°C and three displacement rates. The network dislocation density, dislocation loop radius and loop number density were determined by both X-ray line profile analysis and TEM observations. The dependence of dislocation structure parameters on irradiation conditions and initial network density was obtained.     

High resolution TEM of high burnup UO2 fuel

High-resolution TEM (HRTEM) observations and nano-area EDX analyses were carried out on small intragranular bubbles in the outer region of high burnup UO₂ pellets. Sample was prepered from the outer region of UO₂ pellet, which had been irradiated to the pellet average burnups of 49 GWd/t in a BWR. HRTEM observations and element analyses were made with a 200 KV cold-type field emission TEM (Hitachi FE-2000) having an ultra-thin window EDX (Noran Voyager). Lattice image and nano-area EDX results indicate the presence of 4-8 nm size Xe-Kr bubbles along with fission products of five metal particles, Mo-Tc-Ru-Rh-Pd. Nano-diffraction patterns from bubbles show two different new patterns besides matrix UO₂. From the Xe/U proportion obtained by nano-area EDX peak and nano-diffraction patterns from bubbles, it was concluded that Xe in the small bubbles was present in a solid or near solid state at very high pressure. Furthermore, from the results of high resolution images and diffractions obtained from recrystallized grains in rim structure region, neighboring recrystallized grains were clarified to be present with high angle grain boundaries.     

Study on the characteristic points of boiling curve by using wavelet analysis and genetic neural network

Local singularity of a signal includes a lot of important information. Wavelet transform can overcome the shortages of Fourier analysis, i.e., the weak localization in the local time- and frequency-domains. It has the capacity to detect the characteristic points of boiling curves. Based on the wavelet analysis theory of signal singularity detection, Critical Heat Flux (CHF) and Minimum Film Boiling Starting Point (q_min) of boiling curves can be detected by using the wavelet modulus maxima detection. Moreover, a genetic neural network (GNN) model for predicting CHF is set up in this paper. The database used in the analysis is from the 1960s, including 2365 data points which cover a range of pressure (P), from 100 to 1000 kPa, mass flow rate (G) from 40 to 500 kg m⁻² s⁻¹, inlet sub-cooling (ΔT_sub) from 0 to 35 K, wall superheat (ΔT_sat) from 10 to 500 K and heat flux (Q) from 20 to 8000 kW m⁻². GNN mode has some advantages of its global optimal searching, quick convergence speed and solving non-linear problem. The methods of establishing the model and training of GNN are discussed particularly. The characteristic point predictions of boiling curve are investigated in detail by GNN. The results predicted by GNN have a good agreement with experimental data. At last, the main parametric trends of the CHF are analyzed by applying GNN. Simulation and analysis results show that the network model can effectively predict CHF.     

IBAD MoS2-Ta膜的电子显微与能谱分析

用透射电子显微镜与能谱技术对离子辅助沉积的ＭｏＳ２－Ｔａ膜的形态,结构,组成以及元素的化学态等进行了观察和分析。发现膜在沉积过程中已产生部分晶化,膜体出现衬底鲜明的白色”团簇”点缀的两相特殊形态。ＴＥＭ与ＸＰＳ分析确定白鬼“团簇”属析出的第二相ＴａＳ２。两区都具有（００２）,（１００）和（１１０）取向,面间距与晶格常数都比ＭｏＳ２单晶增大,“白区”的参数又比膜基本略大。