Vaporization and Surface Ionization of LaC2, CeC2, PrC2, NdC2, ThC2 and UC2

The Langmuir vaporization and the surface ionization of LaC₂, CeC₂, PrC₂, NdC₂, ThC₂ and UC₂ from a heated graphite filament have been studied mass spectrometrically. It was found that there were present small amounts of neutral and ionic metal dicarbide molecules in addition to neutral and ionic metal atoms in the LaC₂, CeC₂, PrC₂, ThC₂ and UC₂-C systems with the exception of NdC₂-C, where neither neutral nor ionic metal dicarbide molecules were observed. The reason for this exceptional behavior of the NdC₂-C system is explained by the very small vaporization coefficients, as estimated from the measurements of neutral MC₂/M ratios and ionic MC₂/M ratios.

From the measurements of the heats of vaporization, it was surmised that the ionization potential of Th measured by the surface ionization comparison technique might be too high.     

Vapor Species over Na2O-B2O3-SiO2-Cs2O Glass

Methods for suppression and control of the axisymmetric vertical positional instability are described on the basis of conceptural design studies with the International Tokamak Reactor (INTOR). The shell effect is well known to be useful for suppression of the fast instability. Here shell structures are presented and their usefulness is assessed. Included in the assessments are required modellings of the plasma current for determination of mutual inductances between the plasma and the inductive components around it. Three kinds of models are described and their features are compared to the shell effect. Two kinds of simplified reactor structures are described and studied by comparing them with some control characteristics of the slow instability by a pair of control coils. Their structures are selected so as to result in different shell effects between them, and are consequently found to produce different capacities of power supply, too.     

Ternary Compounds PuNiC2 and PuCoC2

In order to determine a crack propagation rate of less than 10^-8 mm/s in a 24-hour integrated measurement, major parameters of a coupled system of a constant tension specimen and crack depth measurement, based on potential drop method, have been optimized. Influences of sensor geometry, location for detecting potential drop and data processing of the ratio of signal to noise (S/N) were optimized by applying Taguchi's Method. Then a suitable sensor geometry and data processing method were proposed to get a robust measurement system with higher sensitivity and lower susceptibility for geometrical and procedural fluctuations.

By applying the optimal crack propagation rate measurement system, it was confirmed that a crack propagation rate of lxlO^-8 mm/s can be measured under a low concentration condition of hydrogen peroxide with less than a 20% error by a 24-hour integrated measurement.     

纳米SnO2和SnO2／SiO2材料的正电子湮没研究

采用溶胶一凝胶法制备了纯纳米ＳｎＯ２和掺杂ＳｉＯ２的纳米ＳｎＯ２材料，应用Ｘ射线衍射和正电子湮没寿命谱等手段进行了纳米材料的界面结构和纳米晶粒的生长过程，结果表明，所制备的纳米ＳｎＯ２和ＳｎＯ２／ＳｉＯ２材料中只存在两类缺陷，分别对短寿命τ１和中等寿命τ２，材料中两类缺陷的数量比与粒径有关，纳米ＳｎＯ２晶粒生长随热处理温度升高为分两个阶段，低于晶化临界温度时，晶粒生长缓慢，高于此温度时，则生长迅速     

Thermal Conductivity of ThO2-UO2 System

The thermal diffusivity of the ThO₂-UO₂ system in solid solution was measured by laser pulse method at temperatures ranging from 20° to 500°C. Reproducibility of the data was confirmed to be within 3%. The compositions of the samples were ThO₂, ThO₂-1%UO₂, ThO₂-5%UO₂ and ThO₂-10%UO₂.

The thermal conductivity was calculated from measured thermal diffusivity data and the specific heat data available in literature and corrected to zero porosity by using Loeb's equation, in which the shape factor is unity.

The values on ThO₂ thus obtained agreed very well with the data found in literature, throughout the range of temperature of the experiments. The thermal conductivity of ThO₂, ThO₂-1%UO₂, ThO₂-5%UO₂ and ThO₂-10%UO₂, at 20°C, were 0.0312, 0.0288, 0.247 and 0.0184 cal·cm/sec· °C·cm², respectively.     

Study on Redox Equilibrium of UO2 2+/U2 + in Molten NaCl-2CsCl by UV-Vis Spectrophotometry

In order to enhance the understanding of the redox equilibriums of uranyl ions in molten NaCl-2CsCl eutectic salt UV-Vis absorption spectrophotometry measurements were performed for UO₂ ²⁺ in molten NaCl-2CsCl at 923 K under simultaneous electrolytic control of their ratio. A prominent absorption band at 395 nm was assigned to UO₂ ⁺, and its molar absorptivity was determined to be 832±27 mol^-1·l·cm^-1. From the dependence of the rest potential of the melt on the spectrophotometrically determined ratio of [UO₂ ²⁺]/[UO₂ ⁺], the standard redox potential of the couple UO₂ ²⁺/UO₂ ⁺ was determined to be ?0.903±0.007 V vs. Cl₂/Cl^—.     

UO22+在羟基磷灰石上的吸附

以羟基磷灰石（HA）作骨体外模型结合计算机模拟的方法,研究了UO₂²⁺在HA上的吸附行为以及不同种类的螯合剂对其吸附行为的影响。结果表明,15 min后HA对UO₂²⁺的吸附达到平衡,HA颗粒形貌未发生明显改变,吸附过程符合拟二级动力学方程;乙二胺四乙酸（EDTA）和二乙基三胺五乙酸（DTPA）对HA上UO₂²⁺的促排作用类似,能与UO₂²⁺螯合形成大量的络合离子从而达到促排的目的,但会对骨骼无机相表面造成损伤;柠檬酸对吸附在HA上的UO₂²⁺具有较强的解吸作用,但高浓度的柠檬酸会造成HA颗粒形貌显著变化,因此不适合作为铀的促排剂;抗坏血酸对UO₂²⁺在HA上的解吸没有作用,而氨基三乙酸（NTA）会导致HA对铀的吸附率增加。     

Three Phase Region in Ternary System UO2-PUO2-PU2O3

The thermal decomposition of PuF₆ in the temperature range from 100° to 160°C was studied. At 100° and 120°C, no decomposition was detected. At 140° and 160°C, the rate of decomposition during reaction lasting up to 20 hr, and the dependence of the decomposition on the initial PuF₆ pressure were determined. The results are explained by assuming that the rate of decomposition is proportional to the 0.4-th power of PuF₆ pressure. The activation energy of the reaction was found from calculation to be 14.8 kcal/mole.     

D751螯合树脂吸附铀酰,铜,镍,锌及钴的研究

本文研究了国产的具有亚胺二乙酸功能基的大孔螫合树脂D751对铀酰、铜,镍、锌、钴等5种二价离子的吸附性能。测定了树脂对5种二价离子的吸附量与溶液pH值的关系曲线;测定吸附有二价离子的树脂的红外光谱及螯合物解离pH值(DpH)。     

HL-2A Tokamak Edge Modeling with B2

The outer divertor plasma of HL-2A and its associated scrape-off plasma have been simulated using a two-dimensional multi-species fluid code of Braams with a simplified neutral gas model. HL-2A has a double-null closed divertor in separate divertor chambers above and below the nearly circular plasma tours. The computed numerical grid is developed according to an ideal magnetic surface. The calculation is involved only with pure hydrogen plasma. The emphasis has been focused on parametric studies involving variation of the assumptions made for the core plasma. The peak temperatures and the heat flux near the target are of the principal concern。