Calculation of the Optimal Parameters of a Cascade for Separating a Multicomponent Mixture of Isotopes

A method is developed for determining the optimal parameters of a cascade for separating multicomponent isotopic mixtures with a prescribed output concentration for the target isotope. The method is flexible with respect to cascade efficiency criteria. It is based on a systematic calculation of the parameters of a counterflow symmetric cascade with prescribed structural parameters and waste concentration of steps with respect to the valuable (as a rule, the light) isotope. The computational procedure developed includes iterative refinement of the initial approximations of the concentration of nontarget isotopes in the steps. The waste concentration of the steps with respect to the target isotope is varied in order to find the best cascade variant in accordance with the optimization criterion chosen. The properties of cascades optimized with respect to the criterion of minimum total flux are investigated. It is shown that they differ from the nonmixing criteria with respect to the separated isotopes that are conventionally used in the theory of multicomponent separation.     

Limitations of the Model of Centrifugal Separation of a Binary Mixture of Isotopes Based on Approximate Helmholtz Decomposition

A critical analysis is made of a variant of the radial-averaging method based on approximate Helmholtz decomposition. It is shown that in this approach it is assumed that the transit flows are uniform in the radial direction, feed-associated rotational flows and the radial convective transport of an isotope are neglected, and the radial averaging completely neglects the variation of the concentration in radial direction. As a result, the model considered assumes implicitly that the feed flow is small compared with the circulation flow, the accuracy of the model remains within that of the classical radial averaging method, and both theories give the same quantitative results within their range of applicability.     

用于氢同位素分离的置换色谱分离材料的研究进展

置换色谱法是一种较有优势的氢同位素分离方法,而分离材料的性能是决定置换色谱法分离效果的一个关键因素。目前研究的置换色谱分离材料包括钯材料和很多非钯材料。钯虽然价格昂贵,但由于其出色的分离性能而难以用廉价金属或合金来替代。本文简要介绍了置换色谱法分离氢同位素的原理,重点介绍了几种置换色谱含钯分离材料(纯钯、载钯硅藻土、载钯氧化铝、钯铂合金等)的性能,初步分析了置换色谱分离材料的发展方向。     

Method for Calculating and Optimizing a Cascade for Separating a Mixture of Isotopes with Impurities

A method is proposed for calculating and optimizing a cascade separating a mixture of isotopes with impurities. The approach developed optimizes a cascade with arbitrary mixture composition and a large difference in the masses of the components being separated. The application of this method to the separation of a binary mixture of uranium isotopes with impurities is examined. The properties of cascades optimized with respect to the criterion of minimum total flux are investigated. Their correspondence to R cascades with symmetric steps is analyzed. A comparison is made with optimal cascades with no impurities. It is shown that multicomponent potentials can be used to estimate the separation efficiency for a binary mixture of isotopes with an impurity.__________Translated from Atomnaya Energiya, Vol. 98, No. 4, pp. 293–300, April, 2005.     

Potential and Local Efficiency of the Separation of Nonisotopic Binary Gas Mixture by Centrifuge

The balance of value, the separation potential, and the separation efficiency for nine isotopic binary mixture of gases are studied on the basis of a systematic application of local nonequilibrium thermodynamics and the Dirac axioms. In the first approximation of the kinetic theory, a universal classical expression for the potential is substantiated; this expression is valid for nonisotopic mixtures with arbitrary and not only weak or symmetric separation. It is established that the transition from molar to mass terms changes the potential. In contrast to the potential, the observed separation power of a system is invariant under a change of variables.     

Theory of Chromatographic Separation of Isotopes

A fundamental equation for chromatography is derived starting from a very simple concept that the chromatographic movement of species can be expressed as the sum of the movement caused by the external force and the movement caused by the internal concentration gradient and its transformations into appropriate forms are discussed in the cases of ion exchange (or gas) chromatography and ionic migration, without or with a counterflow.

By solving the fundamental equation, making appropriate assumptions, a comprehensive expression which describes the concentration profile is derived for two-isotope systems in any kind of chromatography.     

高丰度硼同位素分离生产技术的研究进展

通过对硼同位素分离生产技术发展过程的分析,认为化学交换精馏法仍是目前能够实现工业化的主要方法,并提出了存在的问题及发展方向。     

Thermal Diffusion Factor for Diatomic Gas Mixture in Multicomponent System

Thermal diffusion factor for diatomic gas mixture was expressed in a practical form applicable to multi- component mixture. Thermal diffusion factor for diatomic gas mixtures was obtained directly from thermal diffusion coefficient in multicomponent mixture by using the relation between thermal diffusion coefficient and thermal diffusion factor, and was shown to be the same as that derived by Mason et al. through a “generalized Stefan-Maxwell equation”. The present expression gives a theoretical proof of the previously reported rough estimate of thermal diffusion factor for hydrogen binary mixtures. Comparing with the present expression for H2-HT binary gas mixture, we have found that the previously reported expression for thermal diffusion factor overestimates in a temperature range from 50 to 1,200 K, but the difference between the previous and the present expressions is small. The present expression is essential to the separative analyses of thermal diffusion column for diatomic gas mixture in multicomponent system, and is consistent with the rough estimate for binary mixture of diatomic gases.     

Calculation of Breakthrough Curve of Multicomponent Hydrogen Isotopes Using Cryosorption Column

The effective tritium system should be designed to recover tritium from DT reactor blanket sweep gas in a form that is easy to transfer to the main fuel cycle. The cryosorption method using a porous adsorbent at the temperature of liquid nitrogen is one of the candidate processes for extracting tritium from the sweep gas. For designing of a cryosorption column for recovery of tritium from hydrogen-swamped helium sweep gas, it is necessary to predict the breakthrough curve for mixture of multicomponent hydrogen isotopes in helium. In this report, a method to calculate the breakthrough curve at cryosorption of multicomponent hydrogen isotopes on molecular sieve 5A, molecular sieve 4A or activated carbon at 77.4 K is presented.     

74Se同位素分离研究

针对分离装置对工作介质的特殊要求，选择SeF6作为分离工作介质，并进行了单机分离试验，获得适用于级联设计的单机参数和单位质量数差的全分离系数γ0。进一步研究中，借鉴其它稳定同位素分离经验，建立了直角级联模型，并开展了级联分离计算，通过理论计算，讨论了74Se同位素级联分离特性。上述研究表明，采用专用方法分离74Se同位素是可行的。     

Two-Phase Module Adaptation for Simulating Separation Processes in Multicomponent Mixtures

Atomic Energy - The results of an adaptation of a two-phase CFD-module for a model of long-term retention of contact discontinuities in the problems of stratification in two-component mixtures are...     

离心法分离锗同位素实验研究

采用气体离心法,以GeF4作为分离介质,通过国产离心机的单机实验成功分离了锗同位素,初步掌握了不同供料流量、分流比下GeF4离心分离的基本全分离系数,得到的基本全分离系数大于1.40,并且通过1-2-1级联实验及相关计算,对高丰度76GeF4产品的生产进行了模拟。实验证明,以GeF4为工作介质,采用国产离心机分离锗同位素可以获得高丰度的76GeF4产品。     

一种多组分分离级联的数值计算方法

本文提出一种计算多组分矩形级联的数值计算方法,该算法以迭代序列差迭代为基础,通过各级物料混合达到收敛。数值计算表明,该方法与其他算法的结果吻合性好,具有很好的收敛性,且其最终收敛精度不依赖初始丰度,不受级联长度的影响,与基本全分离系数大小无关。此方法可以推广到带附加流、阶梯型或多层级联等更复杂的级联计算。     

冠状化合物在锂同位素分离中的应用

锂有两种稳定的同位素且在核能工业中都有重要的应用,工业上分离锂同位素的方法为锂汞齐法,但该法需使用大量有毒的汞,对人类健康和环境卫生带来了严重问题,因此寻找一种绿色有效的替代方法势在必行。自冠醚和穴醚合成后,在锂同位素分离上的优良特性使其成为了国内外研究热点,本工作将近40年来冠状化合物在锂同位素分离中的研究成果进行了系统的归类和总结,为该领域的进一步研究提供参考。     

Separation of Isotope Mixture in a Free Molecular Jet

With the aim of finding the most desirable set of conditions for powder metallurgical preparation of graphite matrix fuels containing thorium carbide, the properties and structure of fuel samples prepared by compacting various mixtures of powdered material followed by heating were investigated.

It was found that of the resulting compacts those consisting of (1) purified and milled natural graphite powder, (2) metallic thorium powder and (3) furfuryl alcohol as binder showed the best properties after heating to 600°C. These compacts possessed 1.90–2.40 g/cc density, 3.5–10.0 kg/mm² Vickers hardness, a thermal expansion coefficient at 900°C of about 14×10^?6/°C in the direction parallel to, and 2.5times;10^?6/°C normal to pressing direction, and a thermal conductivity, in the same temperature range, of 0.02 (parallel) and 0.07cal/cm-sec°C (normal).

Since these favorable properties and structural features are not impaired by heating to about 2,000°C subsequent to treatment at 600°C, it can be said that a new, simple and effective set of conditions for fuel preparation has been found.     

Separation of Isotope Mixture in a Two-Dimensional Supersonic Jet

A numerical analysis is presented on the separation of UF₆ isotope mixture in a supersonic jet from a two-dimensional sonic nozzle, based on the kinetic theory of gas in the continuum region.

The results of calculation for the diffusion flux are found to be in fairly good agreement at low Knudson numbers with the results of experiment given by Becker et al.