DETERMINATION OF REE IN HIGH—PURE Y_2O_3 BY NAA

The method used is divided into two parts. One part is the determination of La, Ce, Pr and Sm by pretreatment neutron activation analysis. The other part is the determination of Ce, Eu, Tb, Tm, Yb and Lu by direct instrument neutron activation analysis. Pretreatment of samples was carried out by P_(507) extraction chromatography. The decontamination factor of Y was 2×10~4. A sensitive method for determination of REE in high-pure Y_2O_3 was established.     

APPLICATION OF INAA TECHNIQUE TO RESEARCH ON THE GEOGAS ANOMALY IN A GOLD DEPOSIT,SOUTHWEST CHINA

A new method of geogas (soil gas) collection and analysis, is briefly introduced. A geogas collector is buried at shallow depth to collect volatile compounds for a period of 60-90 days. The adsorbed compounds are analyzed by INAA. This paper presents the multi-elemental anomaly of a gold deposit, Southwest China.The element contents and the multielemental anomaly of geogas were compared with those in the near- surface soil around the collector, background of the collector, and in gold ores. The geogas anomaly on gold deposit is demonstrated as a direct indicator of subsurface deposits.     

INAA OF RM IAEA-155 WHEY POWDER

An IAEA biological RM IAEA-155 whey powder was analysed for phosphorus, as well as other 24 elements by INAA. The bremsstrahlung photons produced by P is measured by a HpGe spectrometer. The interferences involved in P determination were comprehensively studied and this method was also applied to the determinations of P in several established biological NBS SRMs and proved to be reliable for a wide range of P contents in biological samples.     

MATRIX ABSORPTION CORRECTION OF MEDIUM THICK TARGETS IN XRF

This paper deals with the matrix absorption and enhancement effects of thick targets in energy dispersive X-ray fluorescence analysis. Two kinds of absorption correction methods are studied especially for medium thick targets (5-10 mg/cm2). For analysis of hair samples, both the measurement of absorption correction coefficients and the determination of sensitivity factors using an addition method are introduced. Quantitative analysis of medial thick samples is established. The relative deviation between different methods for most of the elements is found to be less than 5 %.     

Properties of Ternary One Dimensional Plasma Photomic Crystals for an Obliquely Incident Electromagnetic Wave Considering the Effect of Collisions in Plasma Layers

An analytical study is presented on the modal dispersion characteristics, group velocity, and effective group, as well as the phase index of a ternary one dimensional plasma photonic crystal for an obliquely incident electromagnetic wave considering the effect of collisions in plasma layers. The dispersion relation is derived by using the transfer matrix method and the boundary conditions based on electromagnetic theory. The dispersion curves are plotted for both the normal photonic band gap structure and the absorption photonic band gap structure. It is found that the increase in the angle of incidence shifts the photonic band gap toward higher frequencies. Also, the cutoff frequency is independent of collisions.     

Application of Excitation Function to the Prediction of RI Level Caused by Corona Discharge

Radio interference (RI), as an aftereffect of corona discharge, is an important research topic in the field of electromagnetic compatibility, where excitation function is applied broadly to the prediction of RI level. This paper presents the theory of excitation function method used in the RI level prediction. Then, some practical problems related to this method are discussed. The propagation procedure of corona current is solved by the phase-modal transformation, and the impedance matrix of multi transmission lines is calculated by a double logarithmic approximate model of Carson’s Ground-Return impedance. At the same time, in order to calculate the RI level when total line corona is assumed, an analytical formula is deduced for integral operation. Based on the above solutions, an algorithm is presented and applied to the prediction of RI level of a practical overhead transmission line. Comparison of prediction and measurement results indicates that the algorithm proposed in this paper is effective and feasible.     

Study on the performance of a large-size Cs I detector for high energy γ-rays

The measurement of high-energy γ-rays is an important experimental method to study the giant resonance in a nucleus, c reaction in nuclear astrophysics, and so on. The performance of a large-size Cs I detector for crays detection is studied by comparison between the experimental measurements and GEANT4 simulation. The reliability of the simulated efficiency for low-energy γ-rays is verified by comparing with the experimental data. The efficiency of the Cs I detector for high-energy γ-rays was obtained by the GEANT4 simulation. The simulation shows that the detection efficiency of 20 Me V γ-rays can reach 3.8%.     

The Modified Friction and Diffusion Coefficients of Fokker-Planck Equation and Relaxation Rates for Non-Maxwellian Scattering

In this paper, a new method to derive the Fokker-Planck coefficients defined by a non-Maxwellian velocity distribution function for the field particles is presented. The three- fold integral and the new Debye cutoff parameter, which were introduced by CHANG and LI, are applied. Therefore, divergence difficulties and the customary replacement of relative velocity g by thermal velocity vth are naturally avoided. The probability function P（v, Av） for non- Maxwellian scattering is derived by the method of choosing velocity transfer Av, which is a true measure of collision intensity, as an independent variable. The method enables the difference between small-angle scattering and small-momentum-transfer collisions of the inverse-square force to be well clarified. With the help of the probability function, the Fokker-Planck coefficients are obtained by a normal original Fokker-Planck approach. The friction and diffusion coefficients of the Fokker-Planck equation are modified for non-Maxwellian scattering and are used to investigate the relaxation processes for the weakly coupled plasma. The profiles of the relaxation rates show that the slowing down and deflection processes are weakened in the conditions of non-Maxwellian scattering.     

Efficiency-determined method for thermal neutron detection with inorganic scintillator

Because of 3He shortage, sintillator is a promising alternative choice for neutron detection in the field of thermal neutron scattering and imaging. Also, the neutron detection efficiency is difficult to be determined. In this paper, the efficiency for thermal neutron detection is presented by inorganic scintillator using probability principles, supposed that the material of scintillator is uniform in element distribution, and that attenuation length of scintillation light is longer than that of its thickness in the scintillator. The efficiencies for two pieces of lithium glass are determined by this method, indicating the method is useful for determining efficiency of thermal neutron detections.     

CALORIMETRY DETERMINATION OF ~(210)Po IN TARGETS

The polonium-210 activity in raw material targets which was used to make the start neutron source rods of Qinshan Nuclear Power Station was determined in calorimetry. The calorimeter used is a twin-cup isothermal one. It works at room temperature and does not need any device of constant temperature. The instruments used for calorimetry are simple and have good properties. The background is from -1μV to + 2 μ V when the room temperature changs between 16℃ and 28 ℃. The data gotten in calorimetry are in correspondence within ±3.4 % with those from liquid scintillation method after the targets were dissolved, additionally in correspondence within ±1.7% with the data given by Amersham Laboratories for 241Am determination.     

The analysis of reactor fuel and materials in the Department of Analytical Chemistry in the Institute for Nuclear Studies of the Polish Academy of Sciences

The success of nuclear power is due to a large extent to the achievements in the analysis of nuclear fuel and construction materials. This article gives the main results obtained at the Department of Analytical Chemistry in the Institute of Nuclear Studies (INS) of the Polish Academy of Sciences on the determination of uranium in ores and concentrates, and also on the determination of various impurities (boron, rare earth, etc.) in pure preparations of uranium. The experimental results are given for the comparative determination of small amounts of uranium and rare earth by various methods.Article received from the Polish People's Republic.     

The use of special apparatus for rapid analysis of ore production through γ-radiation

RCS installations (radiometer, control, stationary) are widely used for operational determination of quantity and quality of dug ores and commercial yield in various conveyances, (carts, auto-trucks, boxes) and also for isolation of uranium rich broken raw ore, fill material, and dumped rock. This article gives the characteristics of these installations, describes the mine and geological conditions for their use and the problems that can be solved with their aid. For purposes of rational adaptation of RCS-1 and RCS-2 installations to operational determination of excavation yield, evaluation of commercial yield, campaign against metal loss and impoverishment of ore, all mining enterprizes may be divided into two groups: 1) with gross extraction of ore; 2) with predominantly selective extraction of ore. At mining enterprizes utilizing gross extraction, all the operational determination of produced and commercially useful ore is based on rapid γ-analysis of the entire cut stock in mine carts and trucks, by RCS-2 installations. When selective extraction is used, post excavation determination of ore yield is done with RCS-1 installations. This determination is the basis for yield testing of hydrothermal vein sources with low capacity but rich ore bodies. Rapid analysis of rich commercial ores also is done with installations of the RCS-1 type. RCS-2 installations make it possible not only to determine operationally the activity in ore and rock in individual containers, but also to effect full automation of handling work for removal, sorting and unloading of mine carts with broken raw ore.     

Radiometric analysis of ores on conveyers

The physical bases, equipment, and procedure of quantitative proximate analyses of uranium ores on conveyers are briefly examined for the first time in this article. It is shown that this type of measurements may be the main method for the proximate radiometric analysis of ores in mines and factories. Data characterizing the accuracy of results obtained for ores of different material composition are given.     

XRF现场测量中的影响系数法强度校正模型

提出了影响系数法强度校正模型，较好地克服了不同岩性基质成分的基体效应的影响，达到了一次测量确定多种元素含量值的目的。     

Quantitative radiometric measurement of radioactive ores in the natural occurrence

The measurement of gamma radiation of radioactive ores in the natural deposit — directly in the face of a mine working or in a bore hole-permits determination of the radioactive element content in ores without collection of test samples and without chemical analyses.The accuracy of quantitative measurement by gamma rays depends to a considerable degree on correct interpretation of the spectral content of the gamma radiation measured. The gamma-ray spectra of radioactive ores is determined by the process of radiation dispersion and depends on the content of the ore. The intensity of gamma radiation registered by an ore seam depends on the cathode malarial of the counter (tungsten, copper, graphite) as a consequence of the difference in spectral sensitivity of various counters. The relationship of gamma — radiation intensity during measurement with a Geiger counter with various cathodes permits one to characterize the spectral composition of the ore's gamma radiation.In order to express the results in general units, microroentgens per hour, the radiometers are calibrated with an exact standard, but the calibration method does not exclude the radiometer reading dependence on the spectral sensitivity of the counters.In this article are determined the important conversion coefficients connecting gamma-radiation intensity with the content of radioactive elements in ore (see the table) during measurements on the ore seam surface or in borings. During measurements in borings the reverse dissemination of gamma rays having low energy is of great importance.By use of these coefficients calculations of the radioactive element content in ore from counter readings are carried out.     

电感耦合等离子体质谱法测定有机相中镎

建立了电感耦合等离子体质谱法（ICP-MS）测定30%（体积分数,下同）磷酸三丁酯（TBP）/煤油和0.5 mol/L 2-噻吩甲酰三氟丙酮（TTA）/二甲苯中镎的分析方法。样品经异丙醇适当稀释或直接进入ICP-MS分析,在有机进样条件下对仪器和操作参数进行优化和选择,研究了有机相和大量238U在有机基体中引起的基体和质谱干扰,以钍为内标消除基体干扰。研究结果表明：方法的检出限为1×10^-8 g/L（3s,n=10）;相对标准偏差（sr）为0.8%（n=10）（镎质量浓度为2.02 μg/L）;加标回收率为95.5%～115%。该法适用于动力堆乏燃料后处理流程以及预处理后0.5 mol/L TTA/二甲苯中镎的分析。     

核径迹氡探测器在个旧肺癌高发区环境地质研究中的应用

在中国云南省个旧地区应用国产CR-39核径迹氡探测器,测定了各种类型岩石矿物及土壤中氡的浓度,以及大量的居民室内氡浓度,进行以防肺癌为宗旨的氡的环境地质研究。     

Determination of 234U Content in Uranium from Different Deposits

²³⁴U content fluctuations due to many factors are observed in natural uranium obtained for nuclear power production needs. At the same time, the specifications for enriched uranium provide strict requirements for uranium content. These requirements can be satisfied only with timely monitoring of uranium for enrichment.To this end, a method of mass-spectrometric determination of uranium content in samples of uranium-containing ores was developed. The ²³⁴U content in ore samples and concentrates from 20 deposits, located in Russia, Kazakhstan, Ukraine, Uzbekistan, Czechoslovakia, and Germany, was determined.