Uranium Isotope Separation Research Articles

Two-photon laser isotope separation of atomic uranium--Spectroscopic studies, excited state life-times, and photoionization cross sections

Experimental studies are described wherein an atomic beam of uranium vapor produced by electron-beam evaporation is selectively excited and ionized by light from two short-pulse narrow-bandwidth, tuned dye lasers, and detected and analyzed by a mass spectrometer. The total number of ions per pulse produced is small; however, the time of production is known precisely. By counting single ions, using digital logic, and multiplexing the mass spectrometer between U238and U235, it is possible to measure isotope ratios as a function of exciter wavelength and to correct for background effects and spurious ions. These results demonstrated 50 percent enrichment of U235/U238. Excited-state lifetimes were measured by observing yields as a function of the delay between the two laser pulses. In addition, for an excitation wavelength of 4266.325 A, the variation of two-step photoionization efficiency was measured as a function of the wavelength of the ionizing laser. The maximum yield at an ionizing wavelength of 3609 A corresponds to a cross section of 2 \times 10^{-17} cm2for matched linewidths. Also the ionization potential of uranium was determined to be 6.187 ± 0.002 eV.

Macroscopic isotope separation of uranium by selective photoionization

Macroscopic isotope separation of uranium by selective photoionization

Garden hose separation of gaseous isotopes

METHODS of separation of isotopes and in particular the separation of uranium isotopes, have long been studied1,2. Here I present a new variation of the “time-of-flight” process, applicable to all gaseous isotopes, although UF6 gas is considered as the example.

Break-Through Investigation on Uranium Isotope Separation in the System Uranyl Ion Solution Ti(III)-Cationic Resin

A break-through experiment on separation of uranium isotopes was carried out by use of a cation-exchange resin in Ti(III) form. By analyzing the experimental results the apparent equilibrium constants of the order K = 1·00021–1·00034 were determined. The maximum value on the experimental curies of the isotopic ratio versus effluent volume was interpreted by considering two antagonistic isotope effects: one relatively large given by an exchange reaction between U(IV) in resin and U(VI) in solution and another smaller given by the reduction reaction of U(VI) with Ti(III). The difference of the equilibrium constants of the these two isotope effects as a function of temperature was used for the determination of the apparent thermodynamic values of the resultant process, determined experimentally: ΔH0 = 0.8542 cal mol−1 and ΔS0 = 3.33×10−3cal°K−1.

遠心分離機の基本特性，（ＩＩ） ウラン遠心分離における軽ガス添加の影響

The presence of an extraneous light gas must be taken into account in consideration of centrifugal separation of uranium isotopes, when there is inevitable leakage of such a gas through the gas sealant and/or leaking in from the atmosphere.Consideration is first given to the influence of the presence of the light gas on the maximum separative power. Then the basic equation for isotope separation containing a light gas is derived from Hirschfelder's diffusion equations. This equation is solved and the separative performence is expressed in terms of the shape factor and reflux parameter. The formulas for expressing the flow configurations of the gases are obtained for a simple model in which inflow and outflow prevail throughout the centrifuge. The corresponding equation for a model in which the gases flow in two concentric thin streams is also derived.It is concluded that the influence provided by the presence of a light gas is quite significant if the gas penetrates into the effective region of separation of the centrifuge.

ポリ四フッ化エチレン隔膜によるウラン同位体の分離

ポリ四フッ化エチレン隔膜によるウラン同位体の分離

Die physikalischen Grundlagen der Uran235-Anreicherung nach dem Trenndüsenverfahren / The Physics of Uranium235-Enrichment in the Separation Nozzle Process

The effects of the added light gases H2, He, and D2 on the separation of the uranium isotopes in the separation nozzle process are compared experimentally. The superiority of H2 under economically optimum conditions turns out to be caused essentially by its less dissipative nozzle flow characterized by a higher Reynolds number. This advantage is decreased if differences in the flow velocity lose their effects on isotope separation, e. g. at higher expansion ratios. Thus, with He added, the isotope separation effects can get closer to those observed with H2; D2 even can get better than H2, because He and D2 prevent more efficiently UF6 from concentrating rapidly at the outer nozzle wall.

Separation of Uranium Isotopes by Ion Exchange

Separation of Uranium Isotopes by Ion Exchange

The calculation of some isotope separation factors for chemical exchange, distillation, exchange distillation and absorption using UF 6( g)

The reduced partition function of ( 238 UF 6 235 UF 6) g is calculated from the vibrational potential function of Claassen in good agreement with a previous calculation by Mayer and Bigeleisen. Implications of this calculation with respect to chemical exchange reactions of UF 6( g) with complexes of UF 6 are discussed. The quantum mechanical theorem of corresponding states and the vibrational spectra of UF 6( g) , UF 6( l) and UF 6 dissolved in C 7F 16 are used to calculate ln ( f c f g ) in the liquid and solution. These lead to lnα values for distillation and absorption of −4 × 10 −5 and +6 × 10 −6 respectively. 238UF 6 is calculated to be more volatile than 235UF 6 in agreement with experiment. The feasibility of separation of uranium isotopes by exchange chromatography is discussed.

Elution requirements for ion-exchange separation of uranium isotopes

The necessary flow rate and the effective bed length for the ion-exchange separation of uranium isotopes have been calculated using R osen's theory. The applicability of R osen's theory was verified using the isotope exchange of 235U– 238U between the anion-exchange resin bed and 8.4 M hydrochloric acid. The effective feed rate and the estimated column bed length were 8.6 × 10 −3 cm/sec and 3.4 × 10 2 cm, respectively, for the linear isotherm system of U(IV) using 8.4 M hydrochloric acid and the anion-exchange resin, Diaion SA io.

Analyse radiochimique sur filtres échangeurs d'ions: Détermination des isotopes de l'uranium dans l'urine

Radiochemical analysis on ion exchange filters: Determination of uranium isotopes in urine This study develops a new method of determination and separation of uranium isotopes in urine based on filtrations on paper impregnated with ion exchange resins. The operating conditions are determined and two techniques are given. The method is especially suitable for routine monitoring of occupational contamination by uranium. It has also a general interest in radiochemical analysis.

Separation of Uranium Isotopes by Chemical Exchange

The isotope separation effect between U(IV) complex and U(VI) ions was investigated in a mixed system of uranyl solution and cation exchange resin containing wranous ions. The columns were filled with the water slurry of the U(IV)-from resin particles. From the variation of the isotope abundance ratio 235U/238U of U(VI) in the effuent, it was found that (1) the apparent process of the isotope exchange under study is represented as more separate (2) the heavy uranium isotope are concentrated preferentially in the U(IV) complex ions; the equilibrium constant, K, is about 1.0005, independently of the experimental conditions. (3) the rate of isotope exchange is extremely sensitive to temperature.

The Theory of Isotope Separation, especially regarding a Relation between the Multiplication of Elementary Process and the Kineties of Column Operation

Efforts to place separation of isotopes, especially by chromatography or column operation, on a theoretical basis are reviewed. Emphasis is placed on fundamental principles and concepts rather than on details of experimental investigations. Theoretical studies fall into two main lines of approach. The first line of approach is characterized by the application of the ion-exchange or extraction theory to isotope separation; historically this approach as a consequence of the fact that the ion-exchange chromatography was applied to practically the isotope separation of elements. The second line of approach is represented by the chemical exchange method which has hitherto been used in two-phase separation. This approach is applied to interprete the experimental results which were obtained on the uranium isotope separation by the reverse frontal technique and on the lithium isotope separation by the band-elution technique. The relation between the two lines of approach is systematized.

ガス拡散法によるウラン同位体の分離アルミナ隔膜

ガス拡散法によるウラン同位体の分離アルミナ隔膜

The Technical Applications of Radioactivity

AbstractAbstract Additional informationNotes on contributorsRalph T. OvermanAbout the Reviewer: An early worker in the radioisotope and radiation field, Ralph Overman has been active in a variety of research and educational activities in the nuclear field. He was associated with the thermal-diffusion uranium-isotope separation project and the Oak Ridge National Laboratories during and after World War II, and in 1948 established the Training Division of the Oak Ridge Institute of Nuclear Studies. Dr. Overman noiv heads his own consulting firm in Oak Ridge. He is a Fellow of the American Nuclear Society and a member of the Editorial Advisory Committee of Nuclear Science and Engineering, and has published two books in the field of radioactivity and experimental radiochemistry.

Separation of the Isotopes of Uranium by the Separation Nozzle Process

AbstractThe separation nozzle process is based on the partial spatial separation of components of different mass in an expanding supersonic jet stream. The process is of especial interest for the separation of uranium isotopes. Details of a systematic experimental determination of the most favorable operating conditions for such a separation are given and the construction and testing of a closed circulation system, the basic unit of a ten membered pilot cascade separator for uranium isotope separation, is described. The optimum values of the specific cost factors obtained experimentally for the separation nozzle process are compared with the corresponding values estimated for the gaseous diffusion process.

イオン交換体による同位元素分離に関する基礎的知見, (IX)

Breakthrough experiments were carried out to study ion exchange separation of uranium isotopes. Four kinds of solutions containing natural uranium (mole fraction of 235U 0.7200×10-2), (1) 0.05M TnOA/benzene solution saturated with U (IV)-chloro complex, (2) mixture of 0.05M TnOA/benzene solution saturated with U (IV)-chloro complex and 0.05M TnOA/benzene solution saturated with U (VI)-chloro complex, (3) 0.05M TBP/benzene solution with U (IV)-chloro complex, (4) mixture of 0.05M TBP/benzene solution saturated with U (IV)-chloro complex and 0.05M TBP/benzene solution saturated with U (VI)-chloro complex, were passed through 100 cm long, 1.3cm diameter anion exchange resin columns until the composition of the effluents became equal to that of the feed solutions.Near the front of the breakthrough of the solution (4) above, the 235U was found enriched to 0.7324×10-2 (enrichment factor 1.017), while in the case of the solution (2), 235U was depleted to 0.7107×10-2 (enrichment factor 0.987).From the total amounts of 235U enriched or depleted by these breakthrough experiments, single process ion exchange separation factors of uranium isotopes were estimated to be 1.000000 for the solution (1), 1.00033 for the solution (2), 0.99989 for the solution (3), and 0.99988 for the solution (4).Based on these data, the apparent equilibrium coefficients of the electron exchange reaction, 235U (VI)+238U (IV)_??_238U (VI)+235U (IV)were estimated to be 1.0010 and 1.0013 for TnOA/benzene and TBP/benzene systems, respectively. These values are smaller than the value of 1.0020 obtained for 8M hydrochloric acid in the previous paper. The apparent equilibrium coefficient of the electron exchange reaction in the anion exchange resin (Dowex 21 K) was estimated to be 1.00101.0013.

A Theory of Uranium Isotope Separation by Two Phase Distribution Involving Electron Exchange Reaction

A Theory of Uranium Isotope Separation by Two Phase Distribution Involving Electron Exchange Reaction

Multicomponent isotope separation in cascades

This paper presents a theoretical study of multicomponent isotope separation cascades. A theory is developed which leads to the multicomponent analogue of the two component “ideal cascade.” The multicomponent analogue is a “matched abundance ratio cascade.” Multicomponent analogues are derived for “value functions,” “separative work,” and various relationships of importance in two-component isotope separation cascade theory. The theory is applied specifically to the derivation of a multicomponent cost formula which could be used to price uranium containing U-236. (This cost formula is derived merely as an illustration of the theory and no recognition or commitment on the part of the U.S.A.E.C. is implied). The multicomponent matched abundance ratio cascade does not minimize total cascade flow as does the two-component ideal cascade. It is found, however, that for uranium isotope separation the total flow in the matched U-235/U-238 abundance ratio cascade exceeds the minimum by an insignificant fraction for a wide range of U-236 concentrations.

An electromagnetic apparatus with a high resolving power for the separation of the isotopes of the heavy elements

The operating principles and the main features of an electromagnetic apparatus which has been designed and constructed for the separation of isotopes with a relative mass difference of about 1/240 are here described. An axially-symmetric magnetic field is used (focussing angle 225 °) in which the dispersion is proportional to the square of the focussing angle. The dispersion obtained with the separation apparatus is 20 mm for a 1% relative difference in mass. The magnetic field of the apparatus is stabilized to within 0.005% with the help of a circuit containing electron-beam regulators. Ion sources, with a discharge in the vapor of the working and auxiliary substances, were developed for the separation of large and small quantities of the raw material. General-purpose ion collectors were also developed. Some results of the separation of lead, uranium and plutonium isotopes are given. The enrichment factor in the separation of lead isotopes reaches 300, while for uranium and plutonium it is ∼ 1000.