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A model cascade is usually created before constructing a practical isotope separation cascade as the target for approximating a practical cascade. The Q-cascade is a widely used model cascade for continuous profiles in separating multi-component isotope mixtures. The optimization of a Q-cascade with specified concentrations for a target component in the product and waste flows can be conveniently performed by adjusting the mass number (M*) of a virtual component. In previous studies, the M* parameter was treated as identical throughout the entire cascade. This paper proposes further optimization of a Q-cascade by splitting the cascade into segments and allowing each segment to take a different value for M*. An example is presented for separating Cd isotopes; the numerical results demonstrated that segmented Q-cascades achieved better separation performance than traditional Q-cascades. [ABSTRACT FROM AUTHOR]

A numerical method is presented for cascade analysis and design for multi-component isotope separations. A fun-damental issue of interest in cascade analysis and design is the solution of the nonlinear algebraic equation system. This system describes the mass conservation and the separation property of a cascade, which provides the hydraulic state and the component distributions in the cascade. Analytical solutions for the system are only available in a few special cases. Numerical methods are preferred for many of the complicated separation situations; however, the solution process in a numerical method is carried out through iterations and is very sensitive to initial values, which often leads to the failure of the method. Continuation techniques satisfactorily resolve the problem of sen-sitivity. This paper presents computer algorithms in detail to show how the techniques were implemented in order to tackle the problems in constructing different cascades. Various cascades were employed as test problems, includ-ing the well-known matched-R cascade, the quasi-ideal cascade, the less-known matched-X cascade and a newly invented pseudo-binary cascade. Numerical experiments on these cascades demonstrated that these cascades are readily solved with the required properties and that the proposed method is a powerful technique for analyzing and designing isotope separation cascades. [ABSTRACT FROM AUTHOR]

The possibility of estimating the minimum total flow in a cascade with concentrations of a target component given in the product and waste flows by means of a model match abundance ratio cascade (MARC) is studied. The parameters required to describe MARC characteristics are the total number of separation stages, the feed flow location, and the M* parameter, which is equal to a half-sum of mass numbers of the target and the supporting components. Specific research carried out independently in two scientific labs in China and Russia has demonstrated that the integral parameters of the MARC, optimized by the M* parameter, are very close to that of the optimum by the minimum total flow cascade found by means of numerical optimization. The calculation is performed for separation of krypton isotopes when the end component 78Kr and the intermediate component 83Kr are considered to be the targets. It paves the way to use the optimized MARC parameters for two purposes: first, for fast and easy evaluation of the real cascade parameters and second, as an initial guess in its further direct numerical optimization, thereby allowing significant savings in computation time. [ABSTRACT FROM AUTHOR]

In isotope separation pulse cascades are non-conventional and transient processes take place at each stage and in the whole cascade. A numerical method is developed to study the transient process of reaching steady state and applied to square pulse cascades to identify the majors of influence. Without feed and withdrawals, the main factors influencing the transient process are the cascade length and the ratio of the centrifuge holdup to the pipe holdup. With feed and withdrawals, the factors influencing the transient process include the feed, the centrifuge holdup, the pipe holdup, and the cascade length. [ABSTRACT FROM AUTHOR]

A nonconventional gas centrifuge cascade, called the NFSW(no feed and single withdrawal) cascade, is studied in the separation of middle components by means of numerical simulation. The cascade has no feed and only a single withdrawal at either end of the cascade, different from conventional cascades, which usually have two withdrawals at the two ends of the cascade and one feed in between. The material to be separated is loaded in a reservoir at either end, and the desired component is enriched in either the reservoir or the withdrawal at the other end. The effects of the unit separation factor(equivalently, the cascade length) and the ratio of the upstreaming flow rate to the withdrawal rate are investigated on separation. The separation performance is evaluated in terms of the material recovery and the operation time efficiency, and is compared with those of the corresponding conventional cascades and another type of nonconventional cascade, the SW(single withdrawal) cascade. It is found that the NFSW cascade is superior to the conventional cascade and comparable in the material recovery with, but advantageous in the operation time efficiency over the SW cascade. [ABSTRACT FROM AUTHOR]