氚累积取样器设计的实验依据

空气中氚的鼓泡法取样广泛应用于空气及核设施气态流出物中HTO的收集和监测。本工作从理论和实验两个方面详细讨论了分别以水和乙二醇为取样介质时鼓泡器对HTO的收集效率与取样空气温度、湿度、流速、累积体积与鼓泡器内吸收液装量的关系,确定了满足现场要求的长周期累积取样鼓泡器的结构与有关参数,为用于核设施气体排出流氚取样专用装置的设计与使用提供了实验依据。     

ITER中国液态锂铅实验包层模块氚提取系统设计

ITER中国液态锂铅实验包层模块氚提取系统(TES)是通过含0.1%H2的低压氦吹洗气流,在鼓泡器中将液态锂铅内产生的氚交换和载带出来,进入同位素分离系统连接进行氚提取.给出了该系统总体参数、工艺流程、辅助设施等设计.     

氚化水蒸气的鼓泡法制备和鼓泡法取样的研究

本文对鼓泡过程进行了理论和实验研究。如将鼓泡器内装入某种浓度的氚化水,并鼓入干燥空气,它可以成为氚化水蒸气源的发生装置(防护级)。若将鼓泡器内装入普通蒸馏水(不含放射性),鼓入含有氚化水蒸气的空气,它则成为空气中氚化水蒸气的取样装置。本文对鼓泡法制源和鼓泡法取样两种情形分别给出了定量计算公式,并讨论了主要参数的确定办法。最后给出用细     

乏燃料批式溶解器放大设计与水力学试验研究

为提高乏燃料批式溶解器的处理能力,满足我国工业规模后处理厂的要求,以现有的批式溶解器为基础,提出了一种采用笼式固体中子毒物的溶解器放大设计方案,并据此设计和加工了试验样机及试验台架,开展了水力学试验研究。水力学试验结果表明：鼓泡压空流量、鼓泡压空入口位置、液相温度和蒸汽流量是影响溶解器循环速率的显著因素,而负载、气相压力和液位对循环速率的影响相对较小;循环速率随鼓泡压空流量的对数值几乎呈线性增加趋势。     

反应堆退役废物中氚含量的测定方法研究

本文介绍了反应堆退役废物如不锈钢、碳钢锈垢、合金铝和水池底泥固体样品介质中氚含量的测定方法。建立了高温加湿解析、催化氧化、鼓泡器收集的分析方法，并对该方法中有关参数的确定及测量结果的准确性进行了讨论。     

曝气装置结构对多孔板鼓泡特性的影响

气泡体积是决定鼓泡式过滤器性能的重要参数，当使用多孔板作为曝气装置时，孔板结构和气腔状态会对生成气泡体积产生影响。本文采用可视化方法实验研究孔板结构、气腔状态对多孔板鼓泡特性的影响规律。结果表明，气腔无水状态下多孔板鼓泡效果更好；使用有效鼓泡时间能很好地表征多孔板的鼓泡性能；仅当气体流量处于0.35～0.7 L/min、孔间距小于6 mm时，孔间距对多孔板鼓泡性能产生影响；多孔板孔数的确定应保证生成的气泡体积处于气腔控制区。     

氚总排量监测方法研究

本文介绍了一种监测工号氚总排放量的方法,重点介绍为此测量研制的整机式两路同时取样的催化—鼓泡收集空气氚累积取样器。该取样器用经表面特殊防氚处理的铝制多孔乙二醇鼓泡器收集气流中的HTO;专门设计加工的高热效率催化炉和运行自控装置,使它可自动连续一周取样。经三级鼓泡收集对空气氚的取样回收率,0.2m~3小体积取样为98.79％;5m~3大体积取样为92.8％。测量方法灵敏度达到51Bq/m~3。     

氚化水蒸气鼓泡法取样的理论及其定量计算公式的推导

空气中氚化水蒸气(HTO)的鼓泡法取样是一种简单有效的方法。早期实验研究所观察到的收集效率为90—98％。73年 R.V.Osborne 从理论上研究了相关变量对于收集效率的影响,给出了主要参数的测定方法。国内赵亚民同志分别推导的鼓泡法制备标准氚化水蒸气源与鼓泡法取样的定量计算公式,在公式的表达形式与相关参数的测定方法上都较简单直观一些,为人们乐于采用。但是,同一理论的两种不同     

中子辐照后6Li-Al合金靶片中氚的测量方法研究

建立了流气式系统捕集和化学转移法测量^6LiAl合金靶片在中子辐照过程中的渗漏氚和辐照后靶片中总氚量的方法。渗漏氚的捕集方法是：在流气式系统中，用含少量氢的惰性载气将渗漏氚载带出来，经高温催化氧化后被乙二醇鼓泡器捕集；靶片中的氚转移法是用NaOH溶液将合金靶片溶解，气相中的氚采用渗漏氚的捕集方法捕集，液相中的氚则蒸馏到馏分中。最后用液体闪烁计数器分别测量乙二醇鼓泡器和馏分中的氚量。测量结果与理论氚产量基本相符。     

UMo/Zr单片式燃料板起泡行为数值模拟

燃料板的鼓泡临界温度是制定研究试验堆安全系数的标准之一，通常由鼓泡退火实验确定。针对鼓泡退火实验，本研究发展了一种对UMo/Zr单片式燃料板宏观起泡行为进行计算模拟的方法，并计算分析了气腔内裂变气体原子数对鼓泡高度的影响，获得了包壳内的Mises应力和等效塑性应变随温度升高而演化的规律。研究发现，气腔周围包壳产生塑性变形是起泡的一个关键原因。此研究为燃料板起泡机理和关键影响因素分析打下了基础。     

Experimental and numerical studies of void fraction distribution in rectangular bubble columns

Bubbly flow is encountered in a wide variety of industrial applications ranging from flows in nuclear reactors to process flows in chemical reactors. The presence of a second phase, recirculating flow, instabilities of the gas plume and turbulence, complicate the hydrodynamics of bubble column reactors.This paper describes experimental and numerical results obtained in a rectangular bubble column 0.1 m wide and 0.02 m in depth. The bubble column was operated in the dispersed bubbly flow regime with gas superficial velocities up to 0.02 m/s. Images obtained from a high speed camera were used to observe the general flow pattern and have been processed to calculate bubble velocities, bubble turbulence parameters and bubble size distributions. Gas disengagement technique was used to obtain the volume averaged gas fraction over a range of superficial gas velocities. A wire mesh sensor was applied, to measure the local volume fraction at two different height positions. Numerical calculations were performed with an Eulerian–Eulerian two-fluid model approach using the commercial code CFX.The paper details the effect of various two-fluid model interfacial momentum transfer terms on the numerical results. The inclusion of a lift force was found to be necessary to obtain a global circulation pattern and local void distribution that was consistent with the experimental measurements. The nature of the drag force formulation was found to have significant effect on the quantitative volume averaged void fraction predictions.     

Numerical simulation of single bubble condensation in subcooled flow using OpenFOAM

The single condensing bubble behavior in subcooled flow has been numerical investigated using the open source code OpenFOAM. A coupled Level Set (LS) and Volume of Fluid (VOF) method (CLSVOF) model with a phase change model for condensation was developed and implemented in the code. The simulated results were firstly compared with the experimental results, they were in great agreements, and thus the simulation model was validated. The validated numerical model was then used to analyze the condensing bubble deformation, bubble lifetime, bubble size history, condensate Nusselt number and other interesting parameters with different variables in subcooled flow. The numerical results indicated that the initial bubble size, subcooling of liquid and system pressure play an important role to influence the condensing bubble behaviors significantly and bubble will be pierced when the subcooling and initial diameter reach a certain value at the later condensing stage. The bubble diameter history and condensate Nusselt number were found in good agreement with the empirical correlation. The drag force coefficient was predicted well by introducing a reduced drag coefficient.     

Drop Formation Characteristics in High Speed Agitation of Centrifugal Extractor

For the solvent extraction of reprocessing plant, mixer-settler, pulsed column are operated and centrifugal extractor is expected to be used. Mixer-settler has the defect of long contact time. It comes out to cause the solvent damage by radiation in FBR fuel reprocessing. In order to escape from the damage, pulse column and centrifugal extractor should be used for FBR spent fuel. However, the characteristics in centrifugal extractor have not yet been fully analyzed, while those of mixer-settler are advanced much. There- fore, the agitation experiment was made to find out the difference of drop formation between mixer-settler and centrifugal extractor. From the results, the average drop diameter is proportional to Weber number to the power of ?0.58, when the contact time is long. However, the agitation velocity did not affect the average drop size, when the contact time is less than 11.3 s.     

Simultaneous measurement of void fraction and fundamental bubble parameters in subcooled flow boiling

Visualization was performed for the vapor bubbles in water subcooled flow boiling in a vertical heated tube to measure simultaneously the void fraction and the four fundamental bubble parameters: nucleation site density, bubble release frequency, bubble lifetime and bubble size. Using the mass flowrate and liquid subcooling as the experimental parameters, the changes of void fraction and bubble parameters with the wall heat flux were measured. The results of image analysis showed that the vapor void fraction could be approximated by the function of nucleation site density and bubble lift-off diameter; the bubble lift-off diameter was more influential than the nucleation site density. It was hence concluded that the bubble lift-off diameter could be regarded as the key parameter to determine the vapor void fraction under the present experimental conditions. The strong relation of bubble lift-off diameter to superheated liquid layer thickness was indicated for the future model development studies of bubble lift-off diameter.     

Numerical investigation on hydrodynamic performance of liquid lead lithium bubble column using population balance model

Using bubble column to extract tritium from lead lithium (Pb–17Li) eutectic is an effective way in the process of tritium extraction in liquid blanket system, where the hydrodynamic characteristics of the gas–liquid two-phase flow in the columns play a very important role. In order to understand the two-phase flow details and investigate the influence factors on the hydrodynamic performance, in this paper the flow behaviors in the cylindrical bubble columns with different heights and purge gas inlet velocities using computational fluid dynamics coupled with population balance model were simulated. Liquid flow field, bubble Sauter mean diameter, time-averaged gas holdup and two-phase interfacial area for the different cases were obtained and compared. The simulation results showed good agreement with previous studies, and which indicated that bubble size and gas holdup formation are mainly determined by vortical flow. In addition, interfacial area can be enhanced by increasing the purge gas inlet velocity and column height. However, the enhancement effect will trail away when the gas inlet velocity is too fast, and the contribution of column height is relatively small.     

Counter Comment to Dr. Kuznietz for his Comments

A differential-difference equation model is introduced which can describe the dynamics of any type of extractor, whether, mixer settler, pulsed column or rapid contactor.

The differential or difference equation models used by several investigators prove to be particular cases of this model. From the results calculated by this model, it is shown that there exist an optimal stage and an optimal component for monitoring the performance in the control of extractors.

A computer control system for the solvent extraction step of the Purex process is devised with use made of a generalized version of the classical cascade control law, which the authors have named the Multivariate Cascade Control Law.

This law can easily be extended for application to the control of the Purex process as a whole.     

Measurement and modeling of average void fraction, bubble size and interfacial area

The local void fraction, bubble size and interfacial area concentration for co-current air-water bubbly flow through a horizontal pipe of 50.3 mm internal diameter were investigated experimentally using the double-sensor resistivity probe method. The local and area-averaged void fractions and interfacial area concentrations were analyzed as a function of liquid and gas flow rates. These parameters were found to increase systematically with decreasing liquid flow and increasing gas flow. However, variations with the liquid flow were not as significant as with the gas flow. A consistent variation of the gas phase drift velocity and distribution parameter with the liquid flow rate was observed. It was demonstrated that presentation of the average void fraction in terms of flowing volumetric concentration was more appropriate for horizontal bubbly flow. Several bubble break-up mechanisms were discussed. It was concluded that average pressure fluctuations generated by the turbulent liquid fluctuations acting across a bubble diameter are the only mechanism which causes distortion of a bubble. Based on this force and the competing surface tension force, a theoretical model was developed for mean bubble size and interfacial area concentration. The theoretically predicted mean bubble size and interfacial area concentration were found to agree reasonably well with those measured by the double-sensor resistivity method.     

Analysis of subcooled boiling flow with one-group interfacial area transport equation and bubble lift-off model

To enhance the multi-dimensional analysis capability for a subcooled boiling two-phase flow, the one-group interfacial area transport equation was improved with a source term for the bubble lift-off. It included the bubble lift-off diameter model and the lift-off frequency reduction factor model. The bubble lift-off diameter model took into account the bubble's sliding on a heated wall after its departure from a nucleate site, and the lift-off frequency reduction factor was derived by considering the coalescences of the sliding bubbles. To implement the model, EAGLE (elaborated analysis of gas-liquid evolution) code was developed for a multi-dimensional analysis of two-phase flow. The developed model and EAGLE code were validated with the experimental data of SUBO (subcooled boiling) and SNU (Seoul National University) test, where the subcooled boiling phenomena in a vertical annulus channel were observed. Locally measured two-phase flow parameters included a void fraction, interfacial area concentration, and bubble velocity. The results of the computational analysis revealed that the interfacial area transport equation with the bubble lift-off model showed a good agreement with the experimental results of SUBO and SNU. It demonstrates that the source term for the wall nucleation by considering a bubble sliding and lift-off mechanism enhanced the prediction capability for the multi-dimensional behavior of void fraction or interfacial area concentration in the subcooled boiling flow. From the point of view of the bubble velocity, the modeling of an increased turbulence induced by boiling bubbles at the heated wall enhanced the prediction capability of the code.     

窄矩形通道内过冷流动沸腾汽泡生长模型研究

采用高速摄影的方式,对不同系统压力条件下窄矩形通道内汽泡生长过程进行了可视化实验研究,分析了回路系统压力、主流过冷度、壁面过热度、主流速度等热工参数对汽泡生长的影响,并在Zuber公式的基础上建立了可满足不同实验工况的汽泡生长模型。结果表明： Ja 、Bo、Re和无量纲温度θ可较为全面地描述热工参数和流动参数对汽泡生长的影响,在其他条件相同的情况下,汽泡生长指数拟合曲线的K和n值随压力的升高明显减小;θ越大,汽泡的生长时间和所能达到的最大直径越小;在给定的参数范围内模型结果与实验结果符合较好,但由于低压条件下汽泡直径变化的随机性更强,所以模型结果与个别低压实验数据的相对误差较大。     

单气泡生长的高速激光干涉可视化研究

为研究过冷沸腾中气泡的生成机理并为壁面沸腾模型的建立提供数据支撑,本研究采用透光的氧化铟锡（ITO）薄膜作为加热材料,使用激光干涉法和高速相机对池沸腾中单气泡的生长过程进行同步测量,获取了气泡底部微液层的结构和变化过程,同时得到气泡干斑直径、气泡直径等相关参数。研究结果表明,气泡生长过程可分为底部存在微液层的生长阶段和底部完全蒸干后的脱离阶段两部分,两阶段的时长大致相当。在生长阶段,干斑直径和接触直径逐渐增大;在脱离阶段,接触直径逐渐减小。在气泡稳定生长时期,接触直径与气泡直径的比值约为0.6。实验结果验证了微液层边缘存在弯曲结构。本研究获得的气泡微液层演变数据可为气泡生长模型提供实验支撑。