Search

In this paper, numerical simulation methods are used to study issues related to the optimal operating modes of hyperspeed (rotor velocity 1000 m/s and above) model gas centrifuges (GCs) of various lengths and velocities of rotation. The possibility of gas extraction under optimal conditions is studied using three-dimensional modeling. It is shown that for hyperspeed GCs with the Pitot tube as gas extractor, simultaneous attainment of the optimal values for both friction power and waste flux, which are necessary for achieving the optimal operating mode, is unattainable, unlike GC models with a rotor velocity of 600 m/s. It is also shown that the working gas within the shockwave generated by the gas extractor can attain temperatures exceeding 1300 K, which raises the question of a possible accelerated decomposition of uranium hexafluoride. [ABSTRACT FROM AUTHOR]

In the rotating gas in a superstrong centrifugal field, new mechanisms of separation of a binary isotopic gas mixture that are absent from a quiescent gas appear under the impact of waves. In the present work, an analysis of these mechanisms has been made. The mechanism of separation associated with the gas barodiffusion due to the differences between the radial distributions of the perturbation of pressure in the wave and pressure in an unperturbed field has been considered in detail. Dependences of the separation, by the barodiffusion mechanism, on the frequency and amplitude of the wave have been obtained. [ABSTRACT FROM AUTHOR]

A comparison of the efficiencies of the optimum mixing and nonmixing (ideal) cascades comprising stages, the coefficients of separation of a mixture at which are dependent on their parameters, has been performed. It was established that an optimized mixing cascade can have a smaller number of centrifuges, as compared to that of a nonmixing cascade, the separation capacity of whose stages deviate from the optimum one by 1–10%. For an optimum mixing cascade, this deviation is smaller, which can be explained by that the requirement for the fulfillment of the nonmixing condition at the joints of flows in such a cascade narrows the area of search for the parameters of the cascade and thus excludes more effective variants of solving the separation problem. [ABSTRACT FROM AUTHOR]

In order to figure out the driver effect of a curved scoop on three-dimensional flow field in a gas centrifuge (GC), a double-chamber GC was used as the research object. 3D Navier–Stokes equations were solved by the semidiscrete finite volume method with high precision. Numerical results show that there are a bow-shaped shock wave and a detached-body shock wave being generated around the scoop. After the shock wave enters the separation chamber, it moves along a spiral trajectory, which leads to the disturbance of physical variables. Compared with other positions in the rotor, the gas pressure close to the side wall undergoes a more obvious change. The significant axial velocity disturbance is distributed close to the artificial inner boundary, but the main mass transfer of gas occurs near the side wall. The variation of angular integration of axial mass flux in radial direction indicates that there are 3 axial circulations in the separation chamber. [ABSTRACT FROM AUTHOR]

A review of the results obtained by a group of researchers from National Research Nuclear University MEPhI in the course of computer simulation of the gas dynamics and separation of isotopic mixtures in gas centrifuges with ultrafast rotor rotation is presented. The physics of the obtained regularities, as well as unsolved problems are discussed. [ABSTRACT FROM AUTHOR]

A method has been developed to calculate a squared-off cascade with an arbitrary number of external flows by varying the cuts of partial flows of the stages and minimizing the deviations of the calculated feed flows of the stages from specified flows. To minimize the deviations of the flows, a honeybee-colony algorithm ensuring a required accuracy in determining the parameters of the cascade was used. Based on a computational experiment on separation of molybdenum hexafluoride, the high efficiency of the method for concentrating isotopes with an extreme mass number has been shown. [ABSTRACT FROM AUTHOR]

The paper proposes a calculation procedure for square cascades based on cross-sections of partial fluxes. The bees algorithm is used to achieve a constant cross-section for the stage feed flux. The optimization goal is determined as a residual sum of squares of the given stage feed flows calculated through cross-sections of partial fluxes. The paper describes the numerical experiment with germanium tetrafluoride used for multicomponent gas separation of germanium isotopes. It is shown that the proposed calculation procedure can be used to obtain the high concentration of 70Ge and 76Ge isotopes in the square cascade of the stage feed flux. [ABSTRACT FROM AUTHOR]

In order to modeling the gas behavior inside the rotor of a gas centrifuge, a powerful tool is needed to overcome the computational constraints of gas inside the centrifuge along with the ability to apply all drives at the all flow regimes. Due to the suitability of the DSMC method for all flow regimes formed inside the centrifuge, in this paper, the DSMC method is used to analyze the separation performance of a centrifuge in axisymmetric coordinates. For this purpose, using a multi-scale CFD-MD method, first the momentum accommodation coefficients required to use the Cercignani-Lampis-Lord boundary condition are extracted and then, based on that, the behavior of the gas inside a centrifuge machine is investigated using the DSMC method and the amount of separation power is determined. Based on the comparison of the simulation results with the experimental test results, it was shown that using the proposed hybrid method to determine the amount of momentum accommodation coefficients used in the CLL boundary condition of the DSMC method, can increase the accuracy of determining the amount of separation power of the machine up to 8%.

The gas centrifuge process is widely used in the world to separate binary and multi component mixtures of isotopes. The majority of a plant cost is related to the number of centrifuges in a cascade. The cascade should be built so that it uses the fewest possible centrifuges for a given product and waste concentrations. Minimizing the number of centrifuges and the total flow rates, is a key point in designing and optimizing isotope separation cascades. The main purpose of this paper is to present a novel swarm intelligence based algorithm to solve these kinds of problems. This novel algorithm, called the Horse Herd Optimization Algorithm (HOA), is inspired by the behavioral patterns of horses in their habitats. In this work, it is demonstrated that the suggested algorithm can solve complicated multidimensional problems. HOA is tested by some test functions of high-dimensions and the results are compared with the strongest available optimization algorithms. In next, the proposed algorithm is used to optimize gas centrifuge cascades for the separation of binary and multicomponent mixtures of isotopes in several cases. Also, ideal and optimum cascades are compared in different separating regimes of the stages, using this method. Considering the performance of HOA in solving multidimensional problems, this algorithm is proposed for the optimization of long cascades. [ABSTRACT FROM AUTHOR]

In this paper, the optimization of the square and squared-off cascades for the separation of stable isotopes with a certain number of gas centrifuges (GCs) using particle swarm optimization (PSO) and the whale optimization algorithm (WOA) was studied. For this purpose, the "SC-PSO" and "SC-WOA" codes for the square cascade (SC), and the "SOC-PSO" and "SOC-WOA" codes for the squared-off cascade (SOC) were developed. The performance of the PSO and WOA algorithms in the optimization of the square and squared-off cascades as an example for the separation of 124Xe from nine stable isotopes of xenon up to an enrichment of 85% was compared. The recovery coefficient of 124Xe isotope by the codes "SC-PSO", "SC-WOA", "SOC-PSO", and "SOC-WOA" was obtained 86.14, 78.11, 92.84, and 83.41% respectively. The performance of the algorithms indicates the higher yield of the PSO algorithm in the optimization of SC and SOC. The efficiency of the PSO has been demonstrated by the Griewank test function compared with the WOA, the sine cosine algorithm (SCA), and the dragon-fly algorithm (DA) (PSO>WOA>SCA>DA). Furthermore, the results show that SOC performs better than SC. [ABSTRACT FROM AUTHOR]

The mechanical properties of pressings from alloy 1960 in state T1 are determined at 20, 55, 60 and 65°C. Samples of pressings from alloy 1960 in state T1 are tested for creep resistance for up to 5000 h at 55, 60 and 65°C at a stress of 295, 390 and 440 MPa. The creep rate and the deformation of the samples are determined. It is shown that increase of the temperature to 65°C in the tensile tests lowers the strength characteristics of the pressings by 20 – 40 MPa. Increase of the temperature and of the stress in the creep tests elevates the creep rate of the pressings. [ABSTRACT FROM AUTHOR]

Consideration has been given to the distinctive features of multistep concentration of all the molybdenum isotopes in a cascade with a varying type of stages as far as the number of gas centrifuges is concerned. A computational experiment on separation of molybdenum hexafluoride was conducted. A procedure of calculation from the cuts of partial flows of the stages was used which takes account of the dependence of the separation factors of gas centrifuges on their feed flow and the flow-division coefficient. It has been shown that the high efficiency of separation processes is attained with a large number of stages and gas centrifuges and small feed flows of the cascade. [ABSTRACT FROM AUTHOR]

Among the noble gases, Xenon isotopes are the most widely used. So far, no specific strategy has been published for separating all Xenon stable isotopes with the highest number of stable isotopes. In this research, a computational code, SQCAS, is prepared to determine the target isotope separation strategy in light or heavy current. The prepared code investigates the separation of the natural isotopes in proportion to the feed concentration by changing the parameters of the square cascade and modeling it at each step. All stable isotopes of natural xenon are separated using a square cascade in 32 steps for the certain feed (200kg). The proposed square cascade has 20 stages. In each stage, 10 centrifuges were used. Also, the separation factor for the unit mass difference in this research equals 1.2. Using this strategy, the enrichment of nine isotopes increases from 0.9393, 0.0009, 0.01917, 0.2644, 0.408, 0.2118, 0.2689, 0.1044, and 0.087 to 98.72%, 91.3%, 92.79%, 92.63%, 83.77%, 90.12%, 91.64%, 95.68%, and 99.04%, respectively. The results show that the highest recovery is related to the end isotopes, and the lowest recovery is related to Xe-135 isotope.

In this study, the effect of rarefied region in the rotor of the centrifuge was investigated. In a rotor of the centrifuge, the feed inlet is positioned in the rarefied area. The continuum hypothesis is not valid in the rarefied area; therefore, it desires to be analyzed by probabilistic methods like Direct Simulation Monte Carlo (DSMC). In the present study, Computational Fluid Dynamic (CFD) method is used to simulate the continuum area, and the DSMC method is employed in the rarefied area. An implicit coupled density-based scheme was performed for CFD method, and Variable Hard Sphere (VHS) and diffuse model were employed in the DSMC method. Also, the local Knudsen number was defined to determine the interface location between the continuum-rarefied regions (r=0.086 m). The comparison results of pure CFD and CFD-DSMC methods illustrated large differences between the flow properties in the rarefied regions. The results showed that the value of separation power obtained from pure CFD and CFD-DSMC solution is 10.5% different.

A method has been developed for simultaneous concentration of molybdenum isotopes with intermediate atomic mass in two additional products of a multi-flow cascade with a given number of centrifuges in stages. The method takes into account the dependence of the separation factors of the cascade stages on the feed flow of gas centrifuges and the flow division coefficient, which makes it possible to calculate the most efficient operating modes. On its basis, a computational experiment on the separation of molybdenum hexafluoride was carried out. The influence of factors related to the cascade feed flow and to the number of stages and gas centrifuges is investigated. It is shown that the feed flows and the separation factors of the stages of gas centrifuge cascades differ significantly from rectangular and rectangular-partitioned cascades. [ABSTRACT FROM AUTHOR]

To increase the performance of a gas centrifuge, it is necessary to stabilize an axial flow inside the rotor. For this purpose, computer simulation is an effective method. In the present work, a specific solver (ICDB) was developed in OpenFOAM to simulate the gas flow in the rotor. Creating a solver is important because OpenFOAM is free and open-source software. According to a study carried out by a research group, high-speed airflow is considered on a flat plate to assess the accuracy of this solver. To validate the ICDB, the results are compared with those of Fluent software and other researchers. It is found that the results corresponding to ICDB solver are in good agreement with other effects. Moreover, using the ICDB solver and the fluent software, the uranium hexafluoride gas flow inside the axisymmetric rotor was simulated considering different drives such as the thermal drive (wall and caps) and the mechanical drive (scoop). The obtained results show that the developed solver in OpenFOAM can simulate the uranium hexafluoride gas flow inside the rotor.

The features of multistage enrichment of stable xenon isotopes in a cascade with a specified number of gas centrifuges in stages are considered. A computational experiment on xenon separation in a cascade of gas centrifuges is carried out. A procedure for calculation by the slices of partial flows of stages taking into account the dependence of their separation factors on the feed flow and split ratio is used. The parameters of the cascades and stages providing production of highly concentrated xenon isotopes with different mass numbers according to the nine-stage separation scheme are determined. [ABSTRACT FROM AUTHOR]

In order to increase the performance of a gas centrifuge used in the uranium enrichment industry, the gas flow field inside it is studied and simulated. In the present work, the full Navier-Stokes equations using the CFD method are used to simulate the gas flow inside the rotor. For the CFD method, a density-based implicit coupling solver was developed in OpenFOAM software, which was used to simulate the gas flow inside the rotor. The separation power was improved in a sample rotor by adjusting feed flow parameters, wall pressure, wall temperature gradient, and scoop drag force. The results show that the process variable had an optimal value in which the separation power is maximum. In order to achieve the maximum separation power of 12.87 kg UF6 SWU/year, the optimum rotor conditions were determined at a feed rate of 90 g/h, wall pressure of 44 torr, the temperature gradient of 25 K, and drag force of 1557 dyne. This study can be considered an important step in improving the performance of centrifuge separation.

Stage cut control and simulation are the most important aspects in the optimum binary mixture or multi-component multiobjective cascades. Numerical investigation revealed that by controlling the cut of a separation cascade, defined as the ratio of the product rate to the feed rate, it is always possible to separate a multi-component mixture into two specified groups of components, a light group, and a heavy group, in just one separation run. In this paper, the equations related to the cut control are introduced and it is proposed that for controlling stage cuts, putting one valve in the product section of each stage is enough. By solving the set of non-linear equations related to the machine behavior, valve, and pressure drop in the pipelines and junctions, the valve setting for each stage can be obtained. In the end, some examples of an optimal cascade are studied and valve setting parameters are obtained.

This article presents four strategies for separating two stable isotopes of iridium with 99.9% purity. The cascades employed are tapered, square, and squared-off. To design and optimize these cascades, four computational codes were developed using the PSO algorithm. The findings indicate: (1) The tapered cascade strategy cannot achieve 99.90% separation for either type of centrifuge; (2) For the first centrifuge, both square and squared-off cascades strategy successfully separate the isotopes, achieving 99.90% purity, with recovery percentages of 191Ir and 193Ir at 99% and 33%, respectively; (3) For the second centrifuge, only the square cascade strategy achieves 99.90% separation, with recovery percentages of approximately 99% for both isotopes. [ABSTRACT FROM AUTHOR]

The paper proposes a double cascade system for reducing the concentration of 232, 234, 236U isotopes in reprocessed uranium hexafluoride. The greatest decrease in the mass ratio 236U/235U is provided in the product of the first ordinary cascade enriched by the 235U isotope to the concentration less than 20%. For this purpose, a special mode is assigned for the stage operation. The uranium enrichment by 232, 234U isotopes is performed in the second ordinary cascade, which is fed by the first cascade product. After the 232, 234U isotope removal, waste uranium is diluted down to the 235U concentration lower than 5%. The parameter calculation procedure is presented for cascades with the stage separation factors typical for gas centrifuges, which is used for the computational experiment. It is demonstrated that after the 232, 234U isotope removal, waste uranium meets the requirements of the Standard C996-20 of the American Society for Testing and Materials for 232, 234U-enriched uranium hexafluoride. The 236U content in waste uranium is several times lower than after a direct enrichment of reprocessed uranium hexafluoride. [ABSTRACT FROM AUTHOR]

The Boltzmann equation which describes binary collisions between molecules is a very important equation in physics and fluid dynamics. Direct Monte Carlo simulation is one of the methods to solve the Boltzmann equation. The moisture can leak to the fluid pipelines in the various places of cascades so many times through the enrichment operations since the pressure of the most enrichment process units is less than the atmospheric pressure. It causes the solid uranium precipitation on the inner surfaces of rotor and HF production upon the reaction with UF6. In the present work, the effect of concentration and total pressure inside a hypothetical centrifuge for binary component conditions (ZUF6=0.97, ZHF=0.03), (ZUF6=0.93, ZHF=0.07), (ZUF6=0.9, ZHF=0.1), (ZUF6=0.85, ZHF=0.15), and three component conditions (ZUF6=0.9, ZHF=0.05, ZAir=0.05) and (ZUF6=0.8, ZHF=0.1, ZAir=0.1) have been investigated. The results have been compared with those of the Boltzmann distribution function. Moreover, increment in the amount of light gas along with UF6 results in the decrement of ρνz.

The performance of a uranium gas centrifuge which is used in the uranium enrichment industry depends strongly on the gas flow field. The computer simulation is vital to examine the gas flow field. Therefore, in the present study, the capabilities of OpenFoam software for simulating the gas flow inside the rotor for total reflux thermal drive-in axisymmetric mode has been investigated. The results corresponding to the OpenFoam ssimulation have been validated with those of analytical Olander’s model, numerical solution of the Harada’s study, and simulation using Fluent. The simulation results for gas flow inside the rotor of centrifuge showed that the density-based solver was properly chosen and the number of cells, 160×170, was compatible with mesh. The numerical results show that OpenFoam software was capable to examine the gas flow inside the rotor. Also, the simulation of the distribution of Knudsen number confirms the presence of the molecular region near the axis of rotation. OpenFoam is open-source software and there is the ability to solve the molecular region as well as the coding for coupling the continuous and molecular region, the feature which does not exist in the fluent software. The use of open foam is therefore recommended to simulate gas flow inside the rotor.

Bellow is key component of a supercritical gas centrifuge, which has changed the construction of the rotor’s wall and impacted the flow field inside the rotor. In order to analyze the impact of the bellow on the flow field in a gas centrifuge, numerical simulations have been carried out for flow fields with an inner bellow and an outer bellow respectively. The simulations of the flow field are based on the uni-connected hydraulic model and the Iguassu centrifuge model, and 2-D N-S equations are criticized and solved on the staggered grid by a homotopic method and the Newton iteration method. The simulation results show that the outer bellow has almost no effect on circulation flow, but allowable radial height of the outer bellow is very small in order to avoid the possible condensation of the UF6 gas when keeping the waste withdrawal pressure constant. In addition, the inner bellow blocks circulation flow and results in the decrease of the separative power. According to the pareto analysis, the radial height of the inner bellow is the major impacting factor. Another result shows that, when the waste withdrawal pressure is constant, the radial height of the inner bellow is larger, the cut and the separative power is lower. In conclusion, during the design process of a supercritical gas centrifuge with inner bellows, it is necessary to properly design the radial height of the inner bellow to both lower the loss of separative power and ensure an achievable proper cut under safe working conditions.

A concentration equation that describes the mass transfer in transient processes is required for analyzing the separation in transient processes of a gas centrifuge. It is desirable that the equation is simple but is able to reflect the characteristics in transient separation processes to avoid heavy numerical computation. A partial differential equation governing the axial distribution of concentrations in a gas centrifuge is derived from the general equation of mass transfer at unsteady state based on the axial averaging approach. By employing the variable density isothermal rigid body model, the equation is further simplified and analyzed. The dispersion mass source/sink introduced as the result of the model is handled during the simplification to make the concentration solvable.

In this paper, using a new combinatory meshing technique in the axisymmetric coordinate, a MCC-DSMC solver is introduced. Using this solver, the flow and the concentration variation inside a centrifuge machine in a rigid body rotation mode with the DSMC method for a variable hard sphere and a variable soft sphere models and for the mixing hydrogen, argon, and krypton gases are investigated. Our results are compared with the analytical solution. The results indicate that the two collision models are totally in agreement with each other, but the results have some differences with the analytical results obtained from the Boltzmann distribution function. The results show that the presence of the several gases with different molecular weights in a centrifuge shaped a multi-layered radial flow of gas inside the rotor, so that the heaviest gas in the area of the side wall of the rotor, the lightest gas in the region near the axis of the rotor and gases with the medium molecular mass were placed in a layer between them. Furthermore, the variation of the concentration for each component of the mixing gas in the axial direction is also investigated by the DSMC method, otherwise, that it is impossible to investigate it using the analytical solution of the Boltzmann distribution function.

A method has been developed for calculating the parameters of cascades with an assigned number of gas centrifuges in the stages whose separation factors depend on their feed flow and the flow cut. Based on this method, a computational experiment was conducted on separation of molybdenum hexafluoride and concentration of 92,98,100Mo isotopes with a low neutron-capture cross section in the outgoing streams of ordinary and double cascades. The author has determined the features of obtaining isotopically modified molybdenum from waste and selected products of such cascades, which is suitable for creating reactor materials with improved thermophysical characteristics. The influence of the factors associated with the feed flow of cascades and the types of stages, as far as the number of gas centrifuges is concerned, has been studied. It has been shown that the feed flows and the separation factors of the stages of gas-centrifuge cascades differ significantly from rectangular and rectangular-partitioned cascades. [ABSTRACT FROM AUTHOR]

As it is known, uranium enrichment is carried out on industrial scale by means of multistage separation facilities, i.e., separation cascades in which gas centrifuges (GCs) are connected in series and parallel. Design and construction of these facilities require significant investment. So, the problem of calculation and optimization of cascade working parameters is still relevant today. At the same time, in many cases, the minimum unit cost of a product is related to the cascade having the smallest possible number of separation elements/GCs. Also, in theoretical studies, it is often acceptable to apply as an efficiency criterion the minimum total flow to supply cascade stages instead of the abovementioned minimum unit cost or the number of separation elements. In this article, cascades with working parameter of a single GC changing from stage to stage are optimized by two of the abovementioned performance criteria and are compared. The results obtained allow us to make a conclusion about their differences.

In this article, using the direct simulation Monte Carlo (DSMC) method, the gas flow inside the gas centrifuge was modeled simultaneously in the Knudsen and hydrodynamic zones. So that the three-dimensional (3D) simulation of gas centrifuge in the presence of all drivers inside the rotor, including feed, scoop, baffle, etc. was done. The results showed that, the feed is an important factor in creating and intensifying the axial flow formed in the rotor axis, and choke phenomenon occurs at the point of its entry into the rotor. It was further revealed that the amount of separation power obtained from the simulation (using the DSMC method) and the experimental has a difference of 4.3%, showing the agreement of the 3D simulations with reality. • Scoop is responsible for extracting flow and driving axial flow. • Pressure, temperature and molecules collision velocity with scoop inlet affect the drag force in this area. • Due to high rotor wall velocity, supersonic flow hits the scoop, and shock phenomenon occurs. • Feed is an important factor in creation and intensification of axial flow. • The difference in separation power obtained from simulation and experimental is acceptable (4.3%). [ABSTRACT FROM AUTHOR]

The problem of separation of isotopes in a concurrent gas centrifuge is solved analytically for an arbitrary binary mixture of isotopes. The separative power of the optimised concurrent gas centrifuges for the uranium isotopes equals to δU = 12.7 (V/700 m/s)2(300 K/T)(L/1 m) kg·SWU/yr, where L and V are the length and linear velocity of the rotor of the gas centrifuge and T is the temperature. This equation agrees well with the empirically determined separative power of optimised counter-current gas centrifuges.

The results of our study of the filling of a cascade of gas centrifuges with different numbers of stages for separation of nickel isotopes used in nuclear physical research and production of radioactive isotopes are presented. During the filling of the cascade, the natural mixture of nickel isotopes is separated, and the isotopes are concentrated in different cascade stages. The concentrations of nickel isotopes in the stages and flows of light and heavy fractions after the filling of the cascade were shown to depend on the number of stages in the cascade. [ABSTRACT FROM AUTHOR]

We have developed and program-realized a mathematical model of nonstationary separation processes proceeding in cascades of gas centrifuges for separation of multicomponent isotope mixtures. With the help of this model we have calculated the parameters of nonstationary separation processes proceeding in the cascades of gas centrifuges for tungsten isotope separation. It has been shown that the model adequately describes the nonstationary processes in the cascade and is suitable for calculating their parameters during separation of multicomponent isotope mixtures. [ABSTRACT FROM AUTHOR]

The article presents a mathematical model for calculation of nonstationary hydraulic and separation processes in a gas centrifuge (GC) cascade for separation of multicomponent isotope mixtures. The model has been applied to calculate the parameters of nonstationary processes in a GC cascade for separation of krypton, germanium and tungsten isotopes. As a result, the specifics of the excess holdup distribution along the cascade stages has been identified, and variations of the isotope concentrations in a nonstationary process have been revealed. The data obtained show that the proposed mathematical model is able to adequately describe nonstationary hydraulic processes in GC cascades for separation of multicomponent isotope mixtures. Highlights: Mathematical model of cascade for separation of multicomponent isotope mixture has been developed. The model verification has been done. The isotope transient regularities into cascade during nonstationary processes has been identified. [ABSTRACT FROM PUBLISHER]

The question of the choice of technology for a new gas centrifuge uranium enrichment plant is considered and the major factors affecting the cost of construction and operation of such a venture are investigated. Using the method of “essential differences account” (EDA) these factors are compared for two hypothetical plants of equal capacity, using technology provided currently in the uranium enrichment market: the Russian and the West European. The analysis is performed of two parameters that affect the choice of separation technology: 1) the cost of the plant installed capacity, reflecting the capital cost of its construction, and 2) the financial loss due to failure probability of centrifuges in operation, affecting the plant operating costs. It is shown that the main differences in construction costs depend on the characteristics of the gas centrifuge (GC) used. It is also shown that the costs associated with the failed centrifuges replacement are mainly determined by the individual characteristics of centrifuges. The estimates made on the basis of available information show a clear advantage of one of the two considered technological platforms. [ABSTRACT FROM AUTHOR]

For increasing isotopic separation power of a gas centrifuge, the axial circulating flows are created by mechanical or thermal drives. In this paper, the feed injection (mechanical drive) and the axial temperature gradient (thermal drive) are used to induce an internal circulating flow and a model is applied as a governing differential equation of the gas motion. The outcoming of the purely axial flow model is used along with the diffusion equation to obtain concentrations of different isotopes at the gas exodus orifices. The machine separative factor is obtained after specifying xP (the product concentration of lighter isotope) and xW (the waste concentration of lighter isotope) from the enriching and stripping sections. Finally, the dependency of the separative factor to rotor speed, cut and feed flow rate was investigated.

We have developed and realized on software a mathematical model of the nonstationary separation processes proceeding in the cascades of gas centrifuges in the process of separation of multicomponent isotope mixtures. With the use of this model the parameters of the separation process of germanium isotopes have been calculated. It has been shown that the model adequately describes the nonstationary processes in the cascade and is suitable for calculating their parameters in the process of separation of multicomponent isotope mixtures. [ABSTRACT FROM AUTHOR]

Experimental study of the performance of a gas centrifuge can be appreciably simplified if instead of isotopic mixtures, a binary mixture of gases with large molecular weight difference is used. The current study undertook this approach by injecting a 53%–47% (w/w) mixture of “Freon12-Freon22” into a gas centrifuge. The two parameters, whose investigation was the objective of the current study were: the feed flow rate (F), and the clearance between tail scoop and the rotor wall (d). The results demonstrated that changing the scoop-wall clearance has the most significant effect on the cut (θ), so that by fixing “d”, “θ” becomes nearly invariant. The head separation factor (α) exhibited the same dependency, but it was more influenced by the “F” than the “d”. Apparently the following regression exists between the inspected parameters: Decreasing “d” → Decreasing “θ” → Increasing “α”. Variations of the tail separation factor (β) with “F” or “d” was quite slight, even though similar to “α”, it was lowered with increasing of the “F”. The separation capacity (δU) as the most significant parameter of a centrifuge was optimised at the highest value of “F= 40.5 g/h”, and lowest value of “d= 3 mm”. The study achieved a separation capacity and an overall separation factor equal to 195.53 kg Freon/y and 16.87, respectively. These values are several times larger than those of the isotopic mixtures, demonstrating that application of Freons is a useful mean for magnifying the features of a gas centrifuge. [ABSTRACT FROM AUTHOR]