Gas Centrifuge Research Articles

A homotopy algorithm to solve the problems of flows under strong rotation

A finite difference method for numerical simulation of a high speed rotating flow is improved by applying a homotopy algorithm. As a result a large-scale convergence algorithm is constructed to make numerical simulation of a rotating flow in the 2D axisymmetric model of a gas centrifuge for uranium enrichment. The computing code is verified and then applied for calculation of the flow field in a 2D GC operating in a total reflux mode. The peculiarities of an axial circulation flow in a working chamber of a GC are studied. The conclusion about the rate of attenuation of an axial circulation flow is made on the basis of the results obtained.

Calculation of the Present Value of Separative Work for Uranium Isotopes

An economics-mathematical model for performing analytical calculations of the present value of separative work for uranium isotopes in a separation plant currently being designed using gas centrifuge technology is examined. Analytical expressions are obtained for the present value of the separative work, the internal rate of return, and the payback period of the separation plant as a function of its main engineering and economics parameters – productivity (capacity), capital investment, and operating expenses. Calculations of these criteria for investment efficiency are presented for a wide range of initial data. It is shown that the calculation of the present value of separative work must be performed in a complex with other investment efficiency criteria in order to determine their optimal combination.

Mathematical Modeling of Nonstationary Separation Processes in a Cascade of Gas Centrifuges for Separation of Tungsten Isotopes

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.

Minor isotope safeguards techniques (MIST): Analysis and visualization of gas centrifuge enrichment plant process data using the MSTAR model

This paper presents a development related to the use of minor isotope safeguards techniques (MIST) and the MSTAR cascade model as it relates to the application of international nuclear safeguards at gas centrifuge enrichment plants (GCEPs). The product of this paper is a derivation of the universal and dimensionless MSTAR cascade model. The new model can be used to calculate the minor uranium isotope concentrations in GCEP product and tails streams or to analyze, visualize, and interpret GCEP process data as part of MIST. Applications of the new model include the detection of undeclared feed and withdrawal streams at GCEPs when used in conjunction with UF6 sampling and/or other isotopic measurement techniques.

Modeling of nonstationary processes during separation of multicomponent isotope mixtures

ABSTRACTThe 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.

Efficiency criteria for optimization of separation cascades for uranium enrichment

Abstract 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.

Separating Stable Boron Isotopes in Uniflow Gas Centrifuges

A variant of a model of a uniflow gas centrifuge for separating a binary mixture of boron isotopes in the trifluoride form, taking account of the interaction of the rotating gas with a stationary cylindrical central body, is proposed. Expressions are obtained for the maximum admissible enrichment and separation factors and the optimal separative power as functions of the radius of the central body. It is shown that a cascade of uniflow gas centrifuges with more than 95% enrichment of boron trifluoride in terms of the 10B isotope in the requisite quantities for industry can be built in practice.

Multi-detector system approach for unattended uranium enrichment monitoring at gas centrifuge enrichment plants

Improving the quality of safeguards measurements at Gas Centrifuge Enrichment Plants while reducing the inspection effort is an important objective given the number of existing and new plants that need to be safeguarded. A useful tool in many safeguards approaches is the on-line monitoring of enrichment in process pipes. One requirement of such a monitor is a simple, reliable and precise passive measurement of the 186-keV line from 235U. The other information required is the amount of gas in the pipe, which can be obtained by a transmission or pressure measurement. We describe our research to develop such a passive measurement system. Unfortunately, a complication arises in the interpretation of the gamma measurements, from the contribution of uranium deposits on the wall of the pipe to the 186-keV peak. A multi-detector approach to address this complication is presented where two measurements, one with signal primarily from gas and one with signal primarily from deposits, are performed simultaneously with different detectors and geometries. This allows a correction to be made to the 186-keV peak for the contribution from the deposit. We present the design of the multi-detector system and the results of the experimental calibration of the proof-of-principle prototype built at LANL.

Enrichment of Regenerated Uranium in a Gas Centrifuge Cascade with Simultaneous Dilution of 232,236U by Waste and Low-Enrichment Uranium

It is shown that regenerated uranium can be enriched in a gas centrifuge cascade with three feed streams (waste uranium, low-enrichment uranium, regenerated uranium) and simultaneous dilution of the isotopes 232,234,236U. Computational experiments were performed for different 235U content in the low-enrichment feed. The chosen combination of diluents makes it possible simultaneously to lower the separative work expenditure and reduce the consumption of native raw material with respect to not only previously used multi-stream cascades but also a standard cascade for enrichment of native uranium.

Dependence of the separative power of an optimised Iguassu gas centrifuge on the velocity of rotor

PurposeThe purpose of this work is to determine dependence of the separative power of the Iguassu gas centrifuge (GC) on the velocity of the rotor.Design/methodology/approachThe dependence is determined by means of computer simulation of the gas flow in the GC and numerical solution of the diffusion equation for the light component of the binary mixture of uranium isotopes. 2D axisymmetric model with the sources/sinks of the mass, angular momentum and energy reproducing the scoops was explored for the computer simulation. Parameters of the model correspond to the parameters of the so-called Iguassu centrifuge. The separative power has been optimised in relation to the pressure of the gas, temperature of the gas, the temperature drop along the rotor, power of the source of angular momentum and energy, feed flow and geometry of the lower baffle.FindingsIn the result, the optimised separative power depends only on the velocity, length and diameter of the rotor. The dependence on the velocity is described by the power law function with the power law index 2.6 which demonstrate stronger dependence on the velocity than it follows from experimental data. However, the separative power obtained with limitation on the pressure growth with the velocity depends on the velocity on the power ∼ 2 which well agree with the experiments.Originality/valueFor the first time, the optimised separative power of the GCs have been calculated via numerical simulation of the gas flow and diffusion of the binary mixture of isotope.

On the choice of technology for a new uranium enrichment plant

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.

Timely Verification at Large-Scale Gas Centrifuge Enrichment Plants

ABSTRACTThis article examines challenges in international nuclear safeguards pertaining to the timely detection of highly enriched uranium production at large-scale gas centrifuge enrichment plants. To establish where present gas centrifuge enrichment plant safeguards measures and approaches could be strengthened, we have created a discrete time model for simulating hypothetical misuse scenarios, both through transient phases and at steady-state. We find that timely detection of misuse at modern large-scale facilities presents a challenge for international safeguards. A toolbox of unattended measurement systems, along with remote monitoring, however, could be used to improve detection timeliness, enabling the initiation of follow-up activities, potentially on a rapid time scale. These measures, which would need very low false alarm rates, should be implemented in a graded approach, depending on the characteristics of each enrichment plant and an analysis of plausible acquisition paths for the State in which it is situated. Some of these technologies could provide significant benefit to plant operators.

Pay up - or else [ransomware attacks on industrial infrastructure

New information about the capabilities of Stuxnet revealed in the recent documentary film 'Zero Days' has revived concerns about the potential impacts of cyber attacks on critical infrastructure such as power stations, chemical plants and fuel refineries. The movie explains with chilling resonance how, in 2010, the state-sponsored Stuxnet worm managed to gain destructive control of the programmable logic controllers (PLCs), which automated electromechanical processes inside gas centrifuges used for isotopic separation of uranium at Iran's Natanz nuclear facility. While such attacks have caused their share of problems to power stations and utility assets around the world, the newer effects of ransomware has yet to openly turn its disruptive powers on the computerised systems that monitor or manage the physical state of an industrial or infrastructural control system - physical devices such as pumps and valves. This is set to change, warn industry experts, as cyber criminals figure out how to repurpose their dark arts into a profitable model for targets in operational technology (OT) environments.

To “Keep the Genie Bottled Up”: U.S. Diplomacy, Nuclear Proliferation, and Gas Centrifuge Technology, 1962–1972

In the 1960s and early 1970s, U.S. policymakers maintained a complex effort to limit the dissemination of gas centrifuge technology for enriching uranium, which they saw as an inherent nuclear proliferation risk. Recognizing that controls could not stop scientific research and development, U.S. officials nevertheless believed the overseas development of gas centrifuge technology could be slowed. To prevent further dissemination overseas, the United States supported cooperation with European allies that were already developing the technology. Cooperation involved implementation of secrecy and export controls, although a U.S. initiative to include Japan failed because nuclear secrecy was incompatible with Japanese law. The United States tried to deflect Japan's interest in the gas centrifuge by offering to share an alternative technology, gaseous diffusion, for enrichening uranium. That initiative failed, but the U.S. government remained committed to keeping enrichment technologies under secrecy controls.

Mathematical Model of Nonstationary Separation Processes Proceeding in the Cascade of Gas Centrifuges in the Process of Separation of Multicomponent Isotope Mixtures

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.

Opening a proliferation Pandora's box: the spread of the Soviet-type gas centrifuge

ABSTRACTSome scholars have suggested that illicit state-to-state technology transfer and black-market activities are the primary vectors by which technically weak states acquire nuclear weapons. However, a more recent literature has questioned this view, arguing that natural technological change and public-domain information have been potentially more important enablers of proliferation. Articles supporting this perspective have examined gas centrifuge programs in emerging nuclear powers and failed proliferators. This article examines how viable centrifuge-engineering information first circulated and eventually entered the public domain. It then traces the adoption of this technology in nine latent proliferators: countries that are not known to have pursued nuclear weapons immediately, but which nonetheless became capable of making them. The histories of these programs reinforce the argument that public-domain information and basic technology are adequate for proliferation and cannot be reliably limited by technology controls or secrecy.

Impact of waves on the circulation flow in the Iguasu gas centrifuge

2D axisymmetric transient flow induced by a pulsed braking force in the Iguasu gas centrifuge (GC) is simulated numerically. The simulation is performed for two cases: transient and stationary. The braking forces averaged over the period of rotation are equal to each other in both cases. The transient case is compared with the stationary case where the flow is excited by the stationary braking force.Two models of the gas cenrifuge is simulated. There are two cameras in the first model and three cameras in the second one. In the transient case for the two cameras model pulsations almost doubles the axial circulation flux in the working camera. In the transient case for the three cameras model the gas flux through the gap in the bottom baffle exceeds on 15 % the same flux in the stationary case for the same gas content and temperature at the walls of the rotor. We argue that the waves can reduce the gas content in the GC on the same 15 %.

Influence of uncertainties of isotopic composition of the reprocessed uranium on effectiveness of its enrichment in gas centrifuge cascades

The effect of the uncertainties of the isotopic composition of the reprocessed uranium on its enrichment process in gas centrifuge cascades while diluting it by adding low-enriched uranium (LEU) and waste uranium. It is shown that changing the content of 232U and 236U isotopes in the initial reprocessed uranium within 15% (rel.) can significantly change natural uranium consumption and separative work (up to 2-3%). However, even in case of increase of these parameters is possible to find the ratio of diluents, where the cascade with three feed flows (depleted uranium, LEU and reprocessed uranium) will be more effective than ordinary separation cascade with one feed point for producing LEU from natural uranium.

Modeling of filling gas centrifuge cascade for nickel isotope separation by feed flow input to different stages

The article presents results of research filling gas centrifuge cascade by process gas fed into different stages. The modeling of filling cascade was done for nickel isotope separation. Analysis of the research results shows that nickel isotope concentrations of light and heavy fraction flows after filling cascade depend on feed stage number.

Mathematical model of nonstationary hydraulic processes in gas centrifuge cascade for separation of multicomponent isotope mixtures

This article presents results of development of the mathematical model of nonstationary separation processes occurring in gas centrifuge cascades for separation of multicomponent isotope mixtures. This model was used for the calculation parameters of gas centrifuge cascade for separation of germanium isotopes. Comparison of obtained values with results of other authors revealed that developed mathematical model is adequate to describe nonstationary separation processes in gas centrifuge cascades for separation of multicomponent isotope mixtures.