Isotope Separation Techniques Research Articles

Hydrogen Isotope Separation Technique by Quantum Tunneling Effect Used Graphene

Hydrogen Isotope Separation Technique by Quantum Tunneling Effect Used Graphene

A High-Throughput Hot Surface Ion Source for Electromagnetic Radioisotope Separation

An available supply of high-specific-activity radioisotopes was identified by the U.S. Department of Energy as a critical priority to the development and eventual deployment of next-generation medical diagnostic and cancer therapy tools. Work at the University of Missouri Research Reactor Center has been undertaken to develop an electromagnetic isotope separation technique that will leverage the production capabilities of the 10-MW reactor to provide radiolanthanides in quantities suitable for use in preclinical trials. A high-throughput concept design based on a solid tantalum hot surface ion source and an insertable titanium crucible will be described. Significant aspects of the electrical and thermal design of the ion source will be presented. Novel heating and cooling strategies were employed to concentrate heating where it is most needed while attempting to reduce thermal stress where heating is not required. Thermal testing from the commissioning process will be presented to demonstrate the temperature at several key locations in and around the ion source.

A Comprehensive Review of Selected Major Categories of Lithium Isotope Separation Techniques

The ability to generate materials with an enriched isotopic abundance, that is one that differs from natural abundance, is critical in terms of technology. Isotopes are used in a wide range of applications, including radioactive tracers, nondestructive tests, radiotherapy in human medicine, nuclear fuels, and isotope‐substituted compounds for chemistry and biology research, as well as environmental geochemical signature tracers. A commonly discussed research topic is the isotopic separation of various elements—uranium, hydrogen, lithium, and iodine, among many others. Among these isotopes, lithium isotopes are especially important in various applications including strategic areas. These isotopes are light and hence their separation techniques are not very obvious. Herein, all the main categories of Li isotope separation are reviewed in depth with a focus on electrochemical technologies for stable lithium isotope separation.

Theranostic Terbium Radioisotopes: Challenges in Production for Clinical Application.

Currently, research on terbium has gained a momentum owing to its four short-lived radioisotopes, 149Tb, 152Tb, 155Tb, and 161Tb, all of which can be considered in one or another field of nuclear medicine. The members of this emerging quadruplet family have appealing nuclear characteristics and have the potential to do justice to the proposed theory of theranostics nuclear medicine, which amalgamates therapeutic and diagnostic radioisotopes together. The main challenge for in vivo use of these radioisotopes is to produce them in sufficient quantity. This review discusses that, at present, neither light charged particle nor the heavy ion (HI) activation are suitable for large-scale production of neutron deficient terbium nuclides. Three technological factors like (i) enrichment of stable isotopes to a considerable level, (ii) non-availability of higher energies in commercial cyclotrons, and (iii) non-availability of the isotope separation technique coupled with commercial accelerators limit the large scale production of terbium radionuclides by light charged particle activation. If in future, the technology can overcome these hurdles, then the light charged particle activation of enriched targets would produce a high amount of useful terbium radionuclides. On the other hand, to date, the spallation reaction coupled with an online isotope separator has been found suitable for such a requirement, which has been adopted by the CERN MEDICIS programme. The therapeutic 161Tb radionuclide can be produced in a reactor by neutron bombardment on enriched 160Gd target to produce 161Gd which subsequently decays to 161Tb. The radiochemical separation is mandatory even if the ISOL technique is used to obtain high radioisotopic purity of the desired radioisotope.

Production of Mass-Separated Erbium-169 Towards the First Preclinical in vitro Investigations.

The β−-particle-emitting erbium-169 is a potential radionuclide toward therapy of metastasized cancer diseases. It can be produced in nuclear research reactors, irradiating isotopically-enriched 168Er2O3. This path, however, is not suitable for receptor-targeted radionuclide therapy, where high specific molar activities are required. In this study, an electromagnetic isotope separation technique was applied after neutron irradiation to boost the specific activity by separating 169Er from 168Er targets. The separation efficiency increased up to 0.5% using resonant laser ionization. A subsequent chemical purification process was developed as well as activity standardization of the radionuclidically pure 169Er. The quality of the 169Er product permitted radiolabeling and pre-clinical studies. A preliminary in vitro experiment was accomplished, using a 169Er-PSMA-617, to show the potential of 169Er to reduce tumor cell viability.

High-efficiency lithium isotope separation in an electrochemical system with 1-butyl-3-methylimidazolium dicyanamide, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and diethyl carbonate as the solvents

Traditional Li isotope separation methods such as the column exchange process are environmentally hazardous because of the mercury involved. In this research, a high-efficiency Li isotope separation technique with a separation coefficient of 1.054 was developed based on the diffusion and migration of Li isotopes in various solvents. In many solutions, the difference in the diffusion coefficient is small; therefore, the separation effect is not satisfactory. However, due to their unique physical and chemical properties, ionic liquids such as 1-Butyl-3-methylimidazolium dicyanamide and 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and some organic solvents such as diethyl carbonate show higher differences in Li isotope diffusion coefficients and mobilities, hence they can be used to achieve the efficient separation of Li isotopes. The isotope separation with four Li salts (LiBF4, LiCl, LiBr, and LiI) in the three solvents was investigated utilizing these differences. The results show that some Li salts can achieve excellent separation effect in ionic liquids and organic solvents. The corresponding model simulation results also show that the separation effect increases with the increase of the diffusion coefficient difference, and the higher separation coefficient may be realized by searching for the solvent with more differences in the Li isotope diffusion coefficients and mobilities.

Current Status of the NUKLON-2 Space Mission

The NUKLON-2 experiment is aimed at measuring the isotope and charge composition of cosmic rays for medium, heavy, and superheavy ions (Z < 82) with energies between 300 MeV/nucleon and 1 GeV/nucleon. The design of the planned satellite-borne NUKLON-2 cosmic-ray detector is presented. Modeling of the detector’s performance indicates the adopted isotope-separation techniques are effective.

Hyperfine structure and isotope shift measurements on spin-forbidden transitions of atomic gadolinium

We present the first measurements of the [Xe]4f75d16s6p$\;^{11}{F_J}$11FJ excited state hyperfine coefficients and isotope shifts of spin-forbidden transitions of atomic gadolinium (Gd) at 726 and 743 nm in a hollow cathode gas discharge. In addition, we performed a King Plot analysis to determine specific mass shift and field shift constants for these lines. Moreover, we observed King Plot nonlinearity for the 743 nm transition, which is an effect recently proposed to aid in searches for hypothetical new light bosons. Spectroscopic results obtained from this study will facilitate the development of more efficient isotope separation techniques, enable narrowband laser cooling of Gd for novel dipolar physics investigations, and foster technological advances in high precision atomic clocks and quantum enhanced metrology.

(Invited) Lithium Recovery and Lithium-6 Enrichment Using Innovative Electrodialysis with Lithium Ionic Conductor Membrane

As a means of addressing global warming, the world is increasingly turning to the use of Li-ion batteries in electric vehicles and as storage batteries in the home; therefore, there is a growing need for Li. Furthermore, as a fuel for fusion reactors, tritium is produced by the reaction of lithium with neutrons in a tritium-breeding material. Li is primarily recovered from salt lakes in South America but is also present in seawater. Thus, I propose a method for recovering Li from seawater by using innovative dialysis, wherein Li only permeates from the negative electrode side to the positive electrode side through a Li ionic superconductor functioning as a Li separation membrane (LISM) (Fig.1). Measurements of the Li ion concentration at the positive electrode side as a function of dialysis duration showed that the Li recovery ratio increased to approximately 7% after 72 h with no applied electric voltage, and an electrical power of 0.04 V and 0.1 mA was generated. Moreover, other ions in the seawater did not permeate the LISM. With both ends of the LISM bound with a negative and positive electrode, hydrated Li ion was transformed to Li ion only because Li ion can permeate through the LISM [1]. Furthermore, tritium needed as a fuel for fusion reactors is produced via neutron capture by lithium-6 (6Li). However, natural Li contains only about 7.8% 6Li, and enrichment of 6Li up to 90% is required for adequate tritium breeding in fusion reactors. Therefore, new Li isotope separation technique using a Li ionic rconductor functioning as a LISM have been developed. Because the mobility of 6Li ions is higher than that of 7Li ions, 6Li can be enriched on the cathode side of a cell. Using Li0.29La0.57TiO3 (LLTO) as the Li ionic superconductor was prepared, and the relationship between the 6Li separation coefficient and the electrodialysis time was investigated. After electrodialysis, we obtained a maximum of 1.05 for the 6Li isotope separation coefficient. This result showed that the 6Li isotope separation coefficient of this method is the same as that of the amalgamation process using mercury (1.06). Thus, this method has the potential to be a superior 6Li enrichment method to produce 90% enriched tritium breeder for fusion reactors. [1] T. Hoshino, Desalination, 359, 59-63 (2015). Figure 1

Measurements and Simulations of Lithium Isotopes Concentration Fluxes during Electrolytic Lithium -7 Enrichment

Isotopes are utilized in many applications, including physical science analyses, food preservation, archaeology, biology, medicine, pharmaceuticals, national security, and agriculture. The purity is a key requirement for the isotope use. Many different technologies have been used to enrich and separate isotopes. Lithium isotope separation techniques are not very efficient and hence the supply of 7Li is limited. Natural lithium contains a mixture of the two isotopes 6Li and 7Li with abundances of ~ 7.5% and 92.5%, respectively. 7LiOH is often utilized for pH control in pressurized water reactors in the nuclear power industry. The effective separation can be improved to produce purified 7Li or 7Li enriched salt by careful control of diffusion and migration of these isotopes that differ due to their different atomic mass. A systematic study was conducted using computational and experimental techniques for achieving enhanced, environmentally friendly, and reliable 7Li production techniques.

Innovative Separation Technology for Lithium-6 Enrichment Using Electrodialysis with Lithium Ionic Superconductor

Tritium needed as a fuel for fusion reactors is produced via neutron capture by lithium-6 (6Li). However, natural Li contains only about 7.8% 6Li, and enrichment of 6Li up to 90% is required for adequate tritium breeding in fusion reactors. The mercury amalgam method is superior to some of the lithium isotope enrichment methods. In Japan, lithium isotope enrichment methods have been developed to avoid the environmental hazards of using mercury. However, the isotope separation coefficient and efficiency is too low to meet the practical need of large mass production of 6Li. Therefore, new Li isotope separation technique using a Li ionic superconductor functioning as a Li isotope separation membrane (LISM) have been developed [1]. Li ions move by electrodialysis through LISM between the cathode and the anode in lithium solutions. Because the mobility of 6Li ions is higher than that of 7Li ions, 6Li can be enriched on the cathode side of a cell. It has been reported that the difference in the mobility between 6Li and 7Li become large in ionic superconductor. The isotope effect in ionic superconductor is expected to be applicable to isotope separation membrane. In this research, we numerically investigated the ionic mobility of Li isotopes in ionic superconductor. Combing the first principle and the kinetics Monte Calro simulation, we calculate the diffusion constant of 6Li and 7Li. I show the two important effects for the difference in the mobility between isotope of Li. The first is the quantum effect, which decrease the diffusion barrier for Li ion and increase the ratio of the diffusion constant of Li isotopes. The second is the correlation effect between 6Li, 7Li and vacancy. Using Li0.29La0.57TiO3 (LLTO) as the Li ionic superconductor was prepared, and the relationship between the 6Li separation coefficient and the electrodialysis time was investigated. After electrodialysis, we obtained a maximum of 1.04 for the 6Li isotope separation coefficient. This result showed that the 6Li isotope separation coefficient of this method is the same as that of the amalgamation process using mercury (1.06). Thus, this method has the potential to be a superior 6Li enrichment method to produce 90% enriched tritium breeder for fusion reactors. Figure 1

Study of Deuterium Isotope Separation by PEFC

Hydrogen evolution and oxidation reactions were studied on a polycrystalline platinum electrode in 0.05 M D2SO4 solution at 298 K by using a rotating disk electrode, focusing on the kinetic isotope effect on reactivity. The polarization measurements in the evolution reaction regime, on the one hand, revealed two Tafel regions: at low overpotentials close to the equilibrium potential, the Tafel slope was 0.039 V dec−1, suggesting a Volmer-Tafel mechanism; and at potentials around 0.05 V or lower, a slope of 0.168 V dec−1 indicated that a transition to a Heyrovsky-Tafel mechanism occurred. In the oxidation reaction regime, on the other hand, a single Tafel slope of 0.055 V dec−1 was observed at potentials of 0.08 V or lower. Comparing between the deuterium and protium data for the kinetic factors supported the presence of an isotope effect, whereby the deuterium was more easily dissociated on the platinum electrode. The present kinetic result supported the deuterium separation of polymer electrolyte fuel cell (PEFC) in which the mixture gases of H2 and D2 were purged. The deuterium separation factor increased with increasing in the hydrogen utilization. This suggests a new isotope separation technique and also provides useful data for fuel cells.

Novel low energy hydrogen–deuterium isotope breakthrough separation using a trapdoor zeolite

Cs-chabazite, a type of zeolite with caesium counter-cations, possesses interesting gas separation properties due to a highly selective molecular “trapdoor” effect. Herein the use of this material for H2/D2 isotope separation is demonstrated. Isotope separation was achieved using breakthrough separation with a single pass through a packed bed at moderate temperatures (293K) and pressures (0.17MPa) when one species was in a sufficiently low concentration. The breakthrough separation curves were successfully modelled using the Thomas kinetic breakthrough model and the Yoon and Nelson kinetic breakthrough model, where working transferable kinetic rate constants were developed. Use of this material for hydrogen isotope separation would significantly lower the total energy demand compared with current hydrogen isotope separation techniques such as cryogenic distillation and is applicable to separating out low concentrations of D2 (0.0156%) present in standard grade H2.

Recent advances in nuclear physics through on-line isotope separation

The on-line isotope separation technique for the production of accelerated beams of radioactive ions has led to important advances in our understanding of atomic nuclei. These are now reviewed, and further prospects are discussed.

Some Peculiarities of Spin Manifestation in Isotope Effects

Review of the widely known isotope separation techniques where the isotope effect is caused by electron interactions is presented in this paper. An assumption that isotope effects are based on spin interactions can be made.

Experimental Study on Hydrogen Isotope Separation Using a Twin-Bed Periodically Counter-Current Flow Technique

Protium-deuterium isotope separation and tritium enrichment experiments have been carried out under the condition of a total reflux cycle using a continuous twin-bed hydrogen isotope separation technique, i.e., a twin-bed periodically counter-current flow technique. Two beds were packed with Pd and LaNi4.7Al0.3, which show positive and inverse isotope effects, respectively. The separation efficiency was studied experimentally in terms of stoichiometry between hydrogen and adsorbents, cycles, and extraction ratio. The experimental results show that a steady distribution of hydrogen isotopes along the axial direction can be obtained within an operating period of three cycles and a 10% extraction ratio at a moderate H/Pd atomic ratio. The results of a tritium enrichment experiment carried out under optimized conditions indicate that good enrichment efficiency is possible using this method to separate a three-component gas when the extraction ratio is kept small. Since the column used in this experiment is relatively short, there is great potential for this method for meeting the requirements of large-scale operations if long columns or multi-bed combined systems are employed.

High-efficiency technology for lithium isotope separation using an ionic-liquid impregnated organic membrane

The tritium needed as a fuel for fusion reactors is produced by the neutron capture reaction of lithium-6 ( 6Li) in tritium breeding materials. New lithium isotope separation technique using ionic-liquid impregnated organic membranes (Ionic-Liquid-i-OMs) have been developed. Lithium ions are able to move by electrodialysis through certain Ionic-Liquid-i-OMs between the cathode and the anode in lithium solutions. In this report, the effects of protection cover and membrane thickness on the durability of membrane and the efficiency of isotope separation were evaluated. In order to improve the durability of the Ionic-Liquid-i-OM, we developed highly-durable Ionic-Liquid-i-OM. Both surfaces of the Ionic-Liquid-i-OM were covered by a nafion 324 overcoat or a cation exchange membrane (SELEMION™ CMD) to prevent the outflow of the ionic liquid. It was observed that the durability of the Ionic-Liquid-i-OM was improved by a nafion 324 overcoat. On the other hand, the organic membrane selected was 1, 2 or 3 mm highly-porous Teflon film, in order to efficiently impregnate the ionic liquid. The 6Li isotope separation factor by electrodialysis using highly-porous Teflon film of 3 mm thickness was larger than using that of 1 or 2 mm thickness.

Basic technology for 6Li enrichment using an ionic-liquid impregnated organic membrane

The tritium needed as a fuel for fusion reactors is produced by the neutron capture reaction of lithium-6 (6Li) in tritium breeding materials. However, natural Li contains only about 7.6at.% 6Li. In this paper, a new lithium isotope separation technique using an ionic-liquid impregnated organic membrane is proposed. In order to separate and concentrate lithium isotopes, only lithium ions are able to move through the membrane by electrodialysis between the cathode and the anode in lithium solutions. Preliminary experiments of lithium isotope separation were conducted using this phenomenon. Organic membranes impregnated with TMPA-TFSI and PP13-TFSI as ionic liquids were prepared, and the relationship between the 6Li separation coefficient and the applied electrodialytic conditions was evaluated using them. The results showed that the 6Li isotope separation coefficient in this method (about 1.1–1.4) was larger than that in the mercury amalgam method (about 1.06).

Isotopes Separation Method using Physical Vapor Deposition Technique

An isotope separation technique using effusive emission of vapors from the heated molybdenum boat is presented. The technique is applied for the separation of the lithium isotopes. Lithium fluoride with natural isotopic abundance was chosen for evaporation and it was achieved by resistive heating of the molybdenum boat with an exit orifice in the center that provides a point source emission. Glass substrates were placed in a semi-circle around the source of evaporation at different positions of peripheral region to deposit the evaporated material. A non-commercial laboratory developed linear Time of Flight (TOF) mass spectrometer was used for isotopic abundance measurements of lithium in the deposited thin films. The dependence of the size of exit orifice on the separation is also studied for the three exit orifices with diameters of 0.3, 0.6 and 1.0 mm. The separation factors of the isotopes as a function of different peripheral locations are calculated and presented. The abundance of the 6Li isotope has been increased up to 16% on the peripheral positions.

Tritium Removal and Separation Technology Developments

Recent increased interest from regulators and the public has led more organizations to consider the environmental impact and safety considerations of tritium handling. Examples include the significance of the tritium isotope separation system on ITER licensing, remediation of ground water from power utilities and government facilities and concerns of high tritium concentrations within operational CANDU reactors.GE Healthcare, formerly Amersham plc, has been producing tritium-labelled chemicals since the late 1940s. GE’s manufacturing site located near Cardiff, UK has installed a tritium waste treatment and enrichment facility to radically reduce tritium discharges to the environment. This facility employs a continuous processing plant that recovers tritium from a complex mixture of tritiated organic and aqueous waste compounds. Two isotope separation techniques are used to achieve a final pure tritium product, which is used in the manufacturing of labelled compounds.Building upon this experience, together with Special Separations Applications Inc. (SSAI), GE has developed a large-scale diffusion-based isotope separation process as an alternative to conventional cryogenic distillation. Having a tritium inventory an order of magnitude lower than conventional cryogenic distillation, this process is attractive for heavy water detritiation, applicable to single and multi-unit CANDU reactors and research reactors as well as fusion applications. Additionally, the new process has advantages of being cryogen-free, less complex, simple to operate and having improved conventional and radiological safety.