模拟草酸钚沉淀母液中草酸电解破坏研究

采用循环伏安法和线性扫描法对模拟草酸钚沉淀母液中草酸和钚的电化学行为进行研究。研究结果表明,HNO₃介质中的H₂C₂O₄在Pt电极上的氧化为不可逆反应。在模拟的草酸钚沉淀母液中,因Pu(Ⅳ)被C₂O^2-₄络合而未出现Pu(Ⅲ)/Pu(Ⅳ)的氧化还原峰,H₂C₂O₄的氧化峰则清晰可见,H₂C₂O₄的氧化反应仍为不可逆过程。对模拟草酸钚沉淀母液进行恒电流电解,考察了模拟母液中Pu(Ⅳ)初始浓度对草酸电解速率的影响以及电解过程中Pu价态的变化。结果表明,钚浓度为0.002～0.1g/L时,对H₂C₂O₄的电解速率影响不大。恒电流密度下电解可将草酸钚沉淀母液中草酸的浓度破坏到0.001mol/L以下,可满足工艺要求。     

HNO3介质中H2C2O4电解动力学及电解氧化机理

以Pt-Ti（镀铂钛）为阳极,Ti为阴极,对HNO₃介质中的H₂C₂O₄进行恒电流电解,考察HNO₃介质中H₂C₂O₄电解动力学特性及其影响因素,并初步探讨HNO₃介质中H₂C₂O₄的电解氧化机理。研究结果表明：电流密度控制在25～37mA/cm2、HNO₃浓度为2～3mol/L、温度为30~40℃时,电解效果最佳;微量金属离子（Fe^₃+、MnO-4、Ag+）的存在对H2C2O4的电解起催化作用,能较大提高电解速率;电解氧化法破坏H2C2O4的效率高于KMnO4蒸煮法,在工业中有潜在的应用前景。     

氧化硼对铁磷酸盐玻璃陶瓷固化体的影响

研究了不同B₂O₃掺量对铁磷酸盐玻璃陶瓷高放废物固化体结构和性能的影响。应用溶出速率法（DR）对固化体进行了化学稳定性测试,使用傅里叶变换红外光谱（FTIR）和X射线衍射（XRD）方法研究了样品的结构。研究结果表明：玻璃陶瓷固化体的主晶相为独居石;B₂O₃的引入对玻璃陶瓷固化体的化学稳定性影响较大,以10%（摩尔分数）的B₂O₃代替Fe₂O₃制得的固化体化学稳定性最佳,其28d的质量浸出率约为7.81×10^-9g•cm^-2•min^-1;试样中存在大量正磷酸基团［PO₄］^3-和少量焦磷酸基团［P₂O₇］^4-,无偏磷酸基团［PO₃］^-存在,固化体中的B主要以［BO₄］四面体基团形式存在。     

离子交换色谱中硼同位素交换反应平衡常数的理论预测

外部溶液相中B(OH)₃与离子交换树脂相中B(OH)₄^-、B₃O₃(OH)₅^2-、B₃O₃(OH)₄^-之间所发生的同位素交换反应的平衡常数K是离子交换色谱法分离硼同位素研究中的基本参数之一,但难以用实验手段精确测定。本研究利用密度泛函理论（DFT）在B3LYP/6—31G理论水平上计算了气态下B(OH)₃、B(OH)₄^-等的振动频率,用计算得到的频率,基于Urey模型求得B(OH)₃、B(OH)₄^-、B₃O₃(OH)₅^2-、B₃O₃(OH)₄^-的简约配分函数比（RPFR）,进而得到同位素交换反应平衡常数。结果表明,B(OH)₃和B(OH)₄^-间的同位素效应显著,其平衡常数K在25 ℃时为1.025 7,B(OH)₃与B₃O₃(OH)₅^2-和B₃O₃(OH)₄^-反应的平衡常数较小,分别约为1.017 2和1.008 4。     

锌对镍基690合金均匀腐蚀影响的XPS分析

在不加锌和加锌浓度为50ppb的两种模拟压水堆一回路水质环境下,对镍基690合金的腐蚀行为进行了研究。经过腐蚀浸泡1 500h后,用X射线光电子能谱(XPS)对其表面氧化膜结构进行深度分析。结果表明,Zn对内层氧化膜内的NiCr₂O₄和FeCr₂O₄中的Ni和Fe起到了置换作用,形成了ZnCr₂O₄。     

人造岩石固化掺铀模拟放射性焚烧灰

以天然锆英石、模拟放射性焚烧灰、CaCO₃、TiO₂、UO₂为原料,采用高温固相反应,对人造岩石固化掺铀模拟放射性焚烧灰进行研究。借助XRD、SEM、抗浸出性能测试等分析测试方法,研究固化体的性能。结果表明：在空气气氛下烧结,固化体的晶相为CaZrTi₂O₇［Ca（Zr,U）Ti₂O₇］、CaTiSiO₅、CaTiO₃和CaUO₄,一部分U固溶于Ca（Zr,U）Ti₂O₇中;较多CaZrTi₂O₇的生成有利于Ca（Zr,U）Ti₂O₇固溶更多的U;模拟放射性焚烧灰掺量为60%、UO₂含量为6.88%的人造岩石固化体,1～35d铀的归一化浸出率为0.17~2.81μg/(cm²•d),42～192d铀的归一化浸出率为0.09～0.13μg/(cm²•d)。     

八氧化三铀粉末制备与利用

本工作研究U₃O₈粉末制备工艺流程和工艺参数，测试制备出的U₃O₈粉末的物化性能以及U₃O₈粉末添加对UO₂芯块产品质量的影响。分析结果表明：所制备的U₃O₈粉末可加到UO₂粉末中而被回收利用；控制U₃O₈粉末加入量，可调节UO₂芯块的密度和微观组织，制备出合格的UO₂芯块，从而提高了金属铀的直收率和利用率。     

硅胶吸附去除高放废液中的锆

实验研究硅胶对硝酸体系中Zr、Pu(Ⅳ)的静态吸附和动态吸附行为。在1.0～4.0mol/LHNO₃中，硅胶对Zr的静态吸附容量(以干硅胶计)约为20mg/g，对Pu(Ⅳ)的吸附分配系数为0.7～1.4mL/g。随着料液酸度的降低，硅胶对Zr、Pu的吸附增加。动态吸附实验结果表明，进料酸度为2.0mol/LHNO₃时，硅胶吸附柱的工作容量约为3.5倍柱体积。使用2mol/LHNO₃淋洗液可将吸附Zr、Pu后的硅胶柱中的部分Zr、Pu洗脱，但洗脱不完全。用2倍柱体积的0.2mol/LH₂C₂O₄可将硅胶吸附的Zr、Pu解吸下来。硅胶柱用0.2mol/LH₂C₂O₄解吸后复用6次，Zr的穿透曲线位置相同。     

钙钛锆石基组合矿物固溶铈的研究

以ZrSiO₄、CaCO₃、TiO₂、Al₂O₃、Ce₂C₆O₁₂•10H₂O为原料,采用固相反应工艺合成掺Ce钙钛锆石基钛酸盐组合矿物。利用XRD、BSE、EDS等分析方法,研究组合矿物的制备及其对Ce的固溶。结果表明：合成掺Ce钙钛锆石基钛酸盐组合矿物的较佳温度为1230℃;组合矿物的主要晶相为钙钛锆石固溶体,次要晶相是榍石和CaTiO₃的固溶体;CeO₂在组合矿物中的最大固溶量为21.39%;组合矿物固溶Ce⁴⁺的机制较复杂,Ce⁴⁺固溶在Ca²⁺位或Zr⁴⁺位,Al³⁺固溶在Ti⁴⁺位对Ce⁴⁺固溶在Ca²⁺位有电价补偿作用。     

不锈钢表面钚污染的擦拭去污

为了防止污染范围扩大,减少对工作人员、公众和环境的辐射危害,需对钚污染的材料或设备进行去污。本工作分别采用不同种类去污试剂对滴加钚标准溶液后自然风干、加热烘干及浓盐酸腐蚀的三类不锈钢模拟污染样品进行擦拭去污实验。结果表明：盐酸及NaF+H₂C₂O₄+HNO₃两种去污试剂对自然风干的样品去污效率＞95%;5%的盐酸对加热烘干样品的去污效率约为95%;8%~10%的盐酸溶液、5%的硝酸溶液以及NaF+H₂C₂O₄+HNO₃对浓盐酸腐蚀样品的去污效率＞95%。     

Extraction kinetics of ruthenium in the mixture of tri-n-butyl phosphate and n-dodecane

The extraction kinetics of ruthenium in the mixture of tri-n-butyl phosphate and n-dodecane has been investigated experimentally, using a constant interfacial area stirred cell. Effect of stirring speed, temperature, specific interfacial area and concentrations of reactant and nitric acid on the extraction rate of ruthenium were studied to identify the reaction location, extraction reaction regime and also to determine the intrinsic rate constant of the reaction and mass transfer coefficients. A systematic approach was adopted for the determination of rate parameters. Based on experimental results it is concluded that the reaction with the extractant takes place at interface and the overall rate is controlled by both the intrinsic kinetics and the mass transfer of the species involved.     

Simulation of Dual-Electrode Capacitively Coupled Plasma Discharges

Dual-electrode capacitively coupled plasma discharges are investigated here to lower the non-uniformity of plasma density. The dual-electrode structure proposed by Jung splits the electrode region and increases the flexibility of fine tuning non-uniformity. Different RF voltages,frequencies, phase-shifts and electrode areas are simulated and the influences are discussed. RF voltage and electrode area have a non-monotonic effect on non-uniformity, while frequency has a monotonic effect. Phase-shift has a cyclical influence on non-uniformity. A special combination of 224 V voltage and 11% area ratio with 10 MHz lowers the non-uniformity of the original set(200 V voltage and 0% area ratio with 10 MHz) by 46.5%. The position of the plasma density peak at the probe line has been tracked and properly tuning the phase-shift can obtain the same trace as tuning frequency or voltage.     

Two-fluid model and hydrodynamic constitutive relations

Two-fluid formulation for two-phase flow analyses is presented. A fully three-dimensional model is obtained from the time averaging, whereas the one-dimensional model is developed from the area averaging. The constitutive equations for the interfacial terms are the weakest link in a two-fluid model because of considerable difficulties in terms of experimentation and modeling. However, these are of supreme importance in determining phase interactions. In view of this, the interfacial transfer terms have been studied in great detail both for the three- and one-dimensional models. New interfacial area, drag, virtual mass, droplet size and entrainment correlations are presented. In the one-dimensional model, a number of serious shortcomings of the conventional model have been pointed out and new formulations to eliminate them are presented. These shortcomings mainly arose due to the improper consideration of phase distributions in the transverse direction.     

Interfacial area concentration in bubbly flow

Interfacial area concentration is one of the most important parameters in two-phase flow. It is related to mass, momentum and energy transfer at the interface. In bubbly flow, it has close relation to bubble diameter. Interfacial area concentration was measured with particular attention to bubble diameter at inlet. The relationship between bubble diameter and interfacial area was theoretically considered. The possibilities of measurement methods of interfacial area concentration with multiprobes were discussed and a preliminary experiment for one of these methods was carried out.     

二次阳极氧化法制备多孔氧化铝膜

文章介绍采用二次阳极氧化法制备孔洞规则、有序的多孔氧化铝膜的工艺。多孔阳极氧化铝(AAO)膜孔径为20～100nm，孔道相互平行且垂直于表面，深度可达50μm。详细分析了第1次阳极氧化、去除氧化层、第2次阳极氧化、扩孔过程中孔结构发生的变化。研究了不同电解液、阳极氧化温度、外加电压等对多孔氧化铝结构的影响。分析了多孔氧化铝膜的表面及侧面形貌、表面微区成分。在草酸溶液中氧化所得的AAO膜孔径相对在硫酸溶液中的较大。在一定范围内，增加氧化温度及氧化电压能提高AAO膜孔径。     

Measurement of interfacial area concentration in subcooled liquid-vapour flow

In two-fluid modelling, accurate prediction of the interfacial transport of mass, momentum and energy is required. Experiments were carried out to obtain a database for the development of interfacial transport models, or correlations, for subcooled water-steam flow in vertical conduits. The experimental data of interest included the interfacial area concentration, interfacial condensation heat transfer and bubble relative velocity. This paper focuses on the interfacial area concentration. The interfacial area concentration was obtained by measuring the distributions of bubble volume and surface area as well as the area-averaged void fraction at various axial locations in subcooled water-steam condensing vertical upward flow under low flow rate and low pressure conditions. The bubble size and surface area were determined using high-speed photography and digital image processing techniques. The area-averaged void fraction was measured by a single-beam gamma densitometer. The results were compared with existing correlations, which were developed on the basis of data obtained for air-water adiabatic flows. Poor agreement between the present data and the existing correlations was obtained. Accordingly, new correlations suitable for subcooled liquid-vapour bubbly flow are proposed.     

Extraction of hydrogen into vacuum by electrochemical hydrogen pump for hydrogen isotope recovery

For hydrogen isotope recovery, an electrochemical hydrogen pump using CaZr_0.9In_0.1O_3?α under vacuum in the cathode compartment has been proposed. Two types of electrodes—pasted and electroless plated electrodes—were used to evaluate the mass transfer process. When the hydrogen pump was operated using direct current, the voltage between electrodes under vacuum was less than that under atmospheric pressure, regardless of electrode type. This result indicates that the hydrogen pump performance is improved under vacuum. In the case of the pasted electrode, however, the voltage decrease was larger than that in the case of the plated electrode. Electrochemical impedance spectroscopy revealed that the diffusivity in the pasted electrode was smaller under atmospheric pressure than under vacuum. From comparing the microstructures of the two electrode types, the pasted electrode has larger pores and would be more suitable for the hydrogen pump under vacuum.     

Dissolution Kinetics of Nickel Ferrite in Chelating and Reducing Agents

As a first step towards developing a decontaminating solution, the dissolution of synthetically prepared nickel ferrite was studied in low concentrations (<l g/l of EDTA and oxalic acid individually and in combination. The ratio of the molar concentration of the ligand to that of the total iron dissolved was varied from 1 to 4. The dependence of the rate was linear in the case of EDTA and Langmurian in the case of oxalic acid. The effect of addition of low concentrations of citric acid, formic acid, ascorbic acid and Fe(II)-EDTA to EDTA solutions was also studied. The effect of pH in the range of 1.4–8.7, on the kinetics of dissolution in EDTA and oxalic acid medium was also determined.     

Simulation of two-phase flows in vertical tubes with the CTFD code FLUBOX

The computational two-fluid dynamics (CTFD) code FLUBOX is developed at GRS for the multidimensional simulation of two-phase flows. The single-pressure two-fluid model is used as basis of the simulation. A basic mathematical property of the two-fluid model of FLUBOX is the hyperbolic character of the advection. The numerical solution methods of FLUBOX make explicit use of the hyperbolic structure of the coefficient matrices. The simulation of two-phase flow phenomena needs, apart from the conservation equations for each phase, an additional transport equation for the interfacial area concentration. The concentration of the interfacial area is one of the key parameters for the modeling of interfacial friction forces and interfacial transfer terms. A new transport equation for the interfacial area concentration is in development. It describes the dynamic change of the interfacial area concentration due to mass exchange and a force balance at the phase boundary. Results from FLUBOX calculations for different experiments of two-phase flows in vertical tubes are presented as part of the validation.     

Degradation of Microcystin-LR by Gas-Liquid Interfacial Discharge Plasma

In this study, we report on the degradation of microcystin-LR （MC-LR） by gas- liquid interracial discharge plasma. The influences of operation parameters such as average input voltage, electrode distance and gas flow rate are investigated. Experimental results indicate that the input voltage and gas flow rate have positive influences on MC-LR degradation, while the electrode distance has a negative one. After 6 min discharge with 25 kV average input voltage and 60 L/h air aerati by discharge both in on, the degradation rate of MC-LR achieves 75.3%. distilled water and MC-LR solution are measured H202 and 03 generated Moreover, an emission spectroscopy is used as an indicator of the processes that take place on the gas-liquid boundary and inside plasma. Varied types of radicals （O, .OH, CO, 03, etc.） are proved to be present in the gas phase during gas-liquid interfacial discharge.