Zinc Isotope Effects Observed by Liquid Chromatography with Benzo-15-Crown-5 Resin

The chromatographic fractionation in Zn isotopes was performed on the synthesized benzo-15-crown-5 resin at 313 and 343 K. The lighter isotopes were found enriched in the resin phase. The isotope fractionation coefficients (ε) were 3.4 and 2.9×10^?4, 4.7 and 4.7×10^?4, and 6.7 and 5.7×10^?4 for the ⁶⁶Zn/⁶⁴Zn, ⁶⁷Zn/⁶⁴Zn and ⁶⁸Zn/⁶⁴Zn isotopic pairs at 313 and 343 K, respectively. They reflected mass-dependence among the Zn isotopes at each operated temperature but did not show 1/T² -temperature proportionality. The temperature effects of the composition of Zn species both in the solution phase and in the resin phase may account in part for the latter observation. The magnitudes of ε's in this study were comparable to the ones obtained by ion exchange chromatography, but much smaller than those observed in the solvent extraction systems with a crown ether in the organic phase.     

Zinc Isotope Accumulation in Liquid Chromatography with Crown Ether Resin

Liquid chromatographic separation of zinc isotopes was attempted in the breakthrough manner using benzo-15-crown-5 resin as column packing material at 313 K, and a 20 m long development was successfully achieved. The value of the single-stage separation factor was 1.00035 for the ⁶⁶Zn/⁶⁴Zn isotopic pair, 1.00047 for ⁶⁷Zn/⁶⁴Zn pair, and 1.00060 for the ⁶⁸Zn/⁶⁴Zn pair, which were equivalent to those obtained by a 5 m long chromatographic experiment under the same conditions. Contrary to this, the HETP value was 0.19 cm at the 20m development while it had been 0.09 cm at the 5 m development. Connecting separation columns with polytetrafluoroethylene tubes not packed with the resin may be responsible for this migration distance dependence of the HETP.     

Gadolinium Isotope Separation by Cation Exchange Chromatography

Displacement chromatographies of Gd adsorption band in cation exchange resin were performed to observe the isotope effects in the Gd ion exchange processes involving complex forming reagents. The heavy isotope of ¹⁶⁰Gd was found to be enriched at the front boundary of Gd adsorption band and the lighter isotopes of 1MGd, ¹⁵⁶Gd and ¹⁵⁷Gd were enriched at the rear boundary in both cases of 20.1m elution with EDTA and 14 m elution with malic acid, as predicted in the theoretical relations. Observed separation coefficients are 4.9×10^?5, 4.0×10^?5 and 2.5×10^?5for isotopie pairs of ^{156 160}Gd, ¹⁵⁸Gd and ¹⁶⁰Gd, respectively, in the case of EDTA elution. In the case of malic acid elution, smaller separation coefficients were observed as 1.8×10^?5, 1.6 ⁵O^?5 and 0.92×10^?5 for isotopie pairs of ^{156 160}Gd, ¹⁵⁷Gd and^{158 160} respectively.     

Calcium isotope separation by band chromatography using 18-crown-6-ether resin

To develop the ⁴⁸Ca enrichment process, a feasibility study on a band chromatography was made using 9 M HCl solution and crown ether resin synthesized in porous silica beads. Prior to the chromatographic experiments, distribution coefficients, Kd, of Ca²⁺ and Sr²⁺ were measured at different concentrations of these ionic species. The frontal boundary of the chromatography was made by a usual manner of the breakthrough mode of calcium feeding, and the rear boundary was made by introducing strontium as a following ion on the basis of the observed Kd values. It was confirmed that the heavy isotope ⁴⁸Ca was depleted in the rear boundary region, while ⁴⁸Ca was enriched in the front boundary region. The values of separation coefficient ε (= α – 1) in three chromatographic operations at different temperatures were observed as 2 × 10^?3 ~ 3 × 10^?3. The separation coefficients observed in the front boundary regions, where ⁴⁸Ca was enriched, agreed with those observed in the rear boundary regions, where ⁴⁰Ca was enriched.     

Calcium isotope fractionation in liquid chromatography with crown ether resins

Breakthrough mode liquid chromatography was employed to study calcium isotope fractionation. Highly porous silica beads, the inner pores of which were embedded with a benzo-18-crown-6 ether resin or a benzo-15-crown-5 ether resin, were used as column packing material. For both the resins, enrichment of heavier isotopes of calcium was observed in the frontal part of their respective calcium chromatograms. The values of the isotope fractionation coefficient were on the order of 10^?3 and 10^?4 for the benzo-18-crown-6 ether and benzo-15-crown-5 ether resins, respectively. The observed isotope fractionation coefficient was dependent on the concentration of hydrochloric acid in the calcium feed solution; a higher hydrochloric acid concentration resulted in a smaller fractionation coefficient value. The present calcium isotope effects were most probably mass dependent, indicating they came from isotope effects based on molecular vibration. Molecular orbital calculations supported the present experimental results in a qualitative fashion.     

Production of high-purity medical radio isotope 64Cu with accelerator-based neutrons generated with 9 and 12 MeV deuterons

We conducted a feasibility study for producing a high-purity medical radioisotope ⁶⁴Cu from natural zinc with accelerator-based neutrons. ⁶⁴Cu isotopes were produced via the ⁶⁴Zn(n,p) reaction. The accelerator-based neutrons were generated via the C(d,n) reaction using low-energy deuterons of 9 and 12 MeV on a 1-mm-thick carbon target. First, the production purity was estimated using the evaluated nuclear data library JENDL-4.0 and our previously measured thick target neutron yield. We found that even when natural zinc was used as the starting material, significantly high-purity ⁶⁴Cu could be obtained. Next, irradiation experiments for producing ⁶⁴Cu using natural zinc were conducted at Kyushu University Tandem Laboratory, with the amounts of ⁶⁴Cu isotopes and other gamma-emission nuclides measured by a high-purity germanium detector. As a result, high-purity ⁶⁴Cu isotopes of 1.11(49) × 10⁰ and 3.70 (17) × 10⁰ Bq/g/μC were produced with incident deuteron energies of 9 and 12 MeV, respectively.     

Strontium Isotope Effect in Liquid-Liquid Extraction of Strontium Chloride Using a Crown Ether

Isotope effects in a liquid-liquid extraction of strontium with dicyclohexano-18-crown-6 (DC18C6) were investigated. Unit mass enrichment factors were observed to increase with concentrations of strontium salt in an aqueous phase. Isotope distinguishing ability of DC18C6 to strontium isotopes was calculated as an intrinsic separation factor to be K _c =1.00051±0.00004. An odd mass number isotope, ⁸⁷Sr, was recognized to behave differently from even mass number isotopes, ⁸⁴Sr, ⁸⁶Sr and ⁸⁸Sr. The enrichment factor induced by a nuclear property (odd or even mass number) other than the mass difference was ε_O/E = ?8.0 × 10^?4 which was observed with 3.2M Sr aqueous solution. Isotope shift of energy state for 5S-orbital of strontium produces the isotope shift in vibrational energy between the strontium ion and the DC18C6.     

Uranium Isotope Separation by Cation Exchange Chromatography Using Uranous Sulfate Complexes

A nearly ideal displacement chromatography has been realized with an eluent of MgS0₄ and H₂SO₄ in the study of uranium isotope separation by means of cation exchange chromatography using uranous sulfate complexes. Uranium-235 was enriched at the end of the chromatogram and ²³⁸U was enriched at the front. Two long distance displacement experiments have been carried out, keeping an isotopic plateau region on the chromatogram. Consequently, good accumulation of the isotopic fractionation based on uranous-sulfate complex formation reactions obtained. The separation coefficient ε of this system was estimated to be about 5×10^?5.     

Calcium isotope fractionation in liquid chromatography with benzo-18-crown-6 resin in aqueous hydrobromic acid medium

Liquid chromatography operated in a breakthrough mode was employed to study calcium isotope fractionation in the aqueous hydrobromic acid medium. Highly porous silica beads, the inner pores of which were embedded with a benzo-18-crown-6 ether resin, were used as column packing material. Enrichment of heavier isotopes of calcium was observed in the frontal part of respective calcium chromatograms. The values of the isotope fractionation coefficient were on the order of 10^?3. The observed isotope fractionation coefficient was dependent on the concentration of hydrobromic acid in the calcium feed solution; a higher HBr concentration resulted in a smaller fractionation coefficient value. The present calcium isotope effects were most probably mass-dependent, indicating that they mostly came from isotope effects based on molecular vibration. Molecular orbital calculations supported the present experimental results in a qualitative fashion. Chromatography operated in aqueous HBr media is a better system of Ca isotope separation than that operated in aqueous HCl media.     

可活化稳定同位素^70Zn示踪研究儿童膳食中锌的生物利用率

使用中子活化分析法,以国内仅有的低深缩度^70Zn（18．3％）作为可活化稳定浓缩同位素示踪剂,对我国儿童膳食中锌的生物利用率进行了研究。建立了以阴离子树脂交换法对儿童便样中的锌元素进行富集,经反应堆中了辐照、测量和放射化学分离、测定锌的生物利率方法。提出了普适于各种^70Zn浓缩度锌作为示踪剂、以^70Zn和^68Zn和^64Zn的质量丰度进行生物利率率的计算公式。克服了以^68Zn作为唯一的天然锌指示而引入的计算误差。     

Rapid-Swept CW Cavity Ring-down Laser Spectroscopy for Carbon Isotope Analysis

With the aim of developing a portable system for an in field isotope analysis, we investigate an isotope analysis based on rapid-swept CW cavity ring-down laser spectroscopy, in which the concentration of a chemical species is derived from its photo absorbance. Such a system can identify the isotopomer and still be constructed as a quite compact system. We have made some basic experimental measurements of the overtone absorption lines of carbon dioxide (¹²C¹⁶O₂, ¹³C¹⁶O₂) by rapid-swept cavity ring-down spectroscopy with a CW infrared diode laser at 6,200 cm^?1(1.6)mm). The isotopic ratio has been obtained as (1.07±0.13)x 10^?2, in good agreement with the natural abundance within experimental uncertainty. The detection sensitivity in absorbance has been estimated to be 3x 10^?8cm^?1.     

Evaluation of neutron-induced and γ-ray-production cross sections for elemental sulfur

A new evaluation for natural S is described, this was a completely new evaluation done for ENDF/B-V. The secondary neutron cross sections and angular distributions as well as the secondary neutron energy distribution for the continuum inelastically scattered neutrons have been included. In addition, the isotopic cross sections for the various (n, particle) reactions were evaluated with the help of experimental data and model-calculated results to construct the corresponding natural S files. Precompound effects were included. The least abundant isotope ³⁶S was not considered in the evaluation. The resolved resonance region for natural S extends from 1.0 × 10^?5 eV to 1091.0 keV, and the resonance parameters for the three S isotopes ³²S, ³³S and ³⁴S have been evaluated from experimentally determined resonance parameters. The Karlsruhe total S cross-section data extending up to 20 MeV were used to construct a smooth cross-section file. Measurements due to other investigators were also used in the evaluation.     

Carbon and Oxygen Isotope Separation by Plasma Chemical Reactions in Carbon Monoxide Glow Discharge

The separation of carbon and oxygen isotopes in CO glow discharge has been studied. The isotope enrichment in the products was measured by quadru-pole mass spectrometer. The reaction yield and empirical formula of solid phase products were determined by the gas-volumetric analysis. The stable products obtained in our experiment are CO₂ and solid polymers formed on the discharge wall. The polymer consists of both carbon and oxygen and the oxygen/carbon mole ratio in the polymer is 0.35±0.05. The isotope enrichment coefficients show a strong negative dependence on discharge current though the relative reaction yields have an opposite tendency. Consequently, the maximum isotope enrichment coefficients for ¹³C in wall deposit of 2.31 and for ¹⁸O in CO₂ of 1.37 are obtained when the discharge current and the reaction yields are minimum in our experimental range. The experimental results of isotope enrichment have been compared with theoretical values estimated by an analytical model of literature. The dilution mechanism of the isotope enrichment of stable products is inferred from the isotopic distributions of ¹³C and ¹⁸O in products and theoretical predictions for isotope enrichment.     

Isotope Effects in Electrolytic Formation of Lithium Amalgam

Isotope effects in the lithium amalgam formation were studied by using the mercury cathode and LiOH solutions. The electrolyses were carried out at different conditions of both applied voltages 4–10 V, and the concentrations of initially charged LiOH, 0.5–5 mol/dm³. Higher efficiency of electrolytic amalgam formation was observed at higher LiOH concentrations and higher applied voltages. At these conditions, however, significant amount of solid amalgam was produced in the mercury phase. From the isotopic analyses on the samples taken during the electrolyses, it was found that the isotopic equilibrium was attained between the aqueous and the liquid amalgam phases. The isotopic equilibrium constant (isotope separation factor) was determined as 1.056 (average value for all the experiments) at 20°C.     

Burnup Determination of High Burnup and Dry Processed Fuels Based on Isotope Dilution Mass Spectrometric Measurements

Destructive methods were used for the burnup determination of a PWR nuclear fuel irradiated to a high burnup in power reactors, and of a dry processed fuel fabricated from a spent PWR fuel and irradiated in the Hanaro research reactor. The total burnup was determined from a measurement of the Nd and Cs isotope burnup monitors. The methods included U, Pu, ¹⁴⁸Nd, ¹⁴⁵Nd+¹⁴⁶Nd, total of the Nd isotopes, ¹³³Cs and ¹³⁷Cs determinations by the isotope dilution mass spectrometric method (IDMS) by using quadrupole spikes (²³³U, ²⁴²Pu, ¹⁵⁰Nd, and ¹³³Cs). The methods involved two sequential anion exchange resin (AG 1X8 and 1X4) separation procedures and a Cs purification with a cation exchange resin (AG 50WX4) separation procedure. The results obtained by the Nd and Cs isotopes from the mass spectrometric measurement were compared with those by the ORIGEN code.     

Pyrolytic Graphite Irradiated with 4 keV Hydrogen Ions Using Reflection High-Energy Electron Diffraction

Separation of barium isotopes with a selective two-step photoionization process was accomplished using a continuous wave dye laser and ultra-high pressure mercury lamp. Narrow line-width laser light was tuned to the 6s^{2 1}S₀--6s6p ¹P₁ resonance line (553.6 nm), and only a single isotopic component in an atomic beam was excited through the isotope shift. The excited atoms were successively ionized by uv radiation and deflected by a static electric field.

The spectrum of the ion current separated isotopically agreed well with spectroscopic data within the system resolution of 65 MHz. The isotopic enrichment of ¹³⁸Ba was 97%, which corresponded to the selectivity of 1.36. The ionization rate defined as what portion of the incident atoms was ionized was approximately 4x10^?5%. The photoionization cross section was estimated from the experimental results by using the least squares method. The resultant value was (4±1)x10^?23m².     

New Evaluation of Neutron Nuclear Data for Zinc Isotopes

New evaluation of neutron-induced nuclear data for five stable isotopes of zinc (mass numbers A = 64, 66, 67, 68, and 70) was consistently carried out in the incident neutron energy range from 10^?5 eV up to 20MeV. In the low energy region up to about 100keV, the resonance parameters were evaluated by taking account of the available measured data. In the fast neutron region, the comprehensive calculations with nuclear reaction models, in which compound, preequilibrium, and direct processes are taken into account, were performed to estimate cross sections for various reactions and double differential cross sections of emitted neutrons and γ-rays. The comparisons of the evaluated cross sections with the experimental data and existing evaluated nuclear data libraries are made and show a good agreement with the measurements.     

Research of Radioisotope Production with Fast Neutrons, (VI)

Copper-67, the longest-lived radioisotope of copper, was prepared by using the reaction ⁶⁷Zn(n p,)⁶⁷Cu. Zinc enriched in ⁶⁷Zn up to 93.4% was irradiated in JRR-1 reactor for 5hr with a fast neutron flux of 1.5×10¹²n/cm²/sec. Copper-67 formed in the zinc target was separated by anion exchange separation using the chloro-complex of the metals. The yield of ⁶⁷Cu and radiochemical impurity were investigated. Seventeen millimicrocuries of ⁶⁷Cu was obtained from 1mg of zinc. No radioactive impurities other than ⁶⁴Cu were not found. Even with the use of enriched target, a more ^MCu was produced than ⁶⁷Cu. The proportion of ⁶⁷Cu to total copper radioactivity was 26% immediately after the irradiation.     

Chromatographic Study on Boron Isotopic Fractionation at High Pressure

Boron isotopic fractionation factor (S) between boron adsorbed onto kaolin clay and boron in aqueous solution was determined by break-through column chromatography at 25.0 MPa at 5 and 25°C. The S values obtained were 1.0021 at 5°C and 1.0011 at 25°C, and were smaller than those obtained by the batch method performed at the atmospheric pressure at room temperature. Theoretical calculations estimate that more than 90% of boron in the clay phase was taken up as B(OH)₃-form at high pressures. Combining the present S values with preliminarily obtained one at 12.0 MPa, it is likely that S value decreases with increasing pressure, which suggests that the difference of the partial isotopic molar volumes between ¹⁰B(OH)₃ and ¹¹B(OH)³ is larger than that of the volumes between ¹⁰B(OH)₄ ^? and ¹¹B(OH)₄ ^?.     

自动电位滴定硼浓度方法在MOFs对硼同位素分离效果测定中的应用

金属 有机骨架（MOFs）材料作为吸附剂具有吸附硼同位素的潜力,为系统研究硼同位素效应,本文建立测定硼酸溶液中硼浓度的自动电位滴定法,以三种MOFs为例测定其对硼同位素的分离效果。采用弱酸强化法,甘露醇用量为理论用量的4倍,硼酸标准物质的测量值与参考值之差最小（-0.000 13 g）,方法的测量不确定度为0.000 2~0.000 8,测量精度为0.10%~0.40%,方法有效、可靠。应用建立的自动电位滴定法测定吸附前、后硼酸溶液的硼浓度,用MC-ICP-MS测定吸附前、后硼酸溶液的硼同位素丰度比¹⁰B/¹¹B,以Cu-MOF-OCH₃、UiO-66-NH₂、MIL-101(Cr)-2,3-OH三种MOFs材料为例,测定其对硼同位素的静态分离效果。结果表明,Cu-MOF-OCH₃、UiO-66-NH₂和MIL-101(Cr)-2,3-OH对硼同位素的分离因子(S)分别为1.066、1.037和1.079,均大于商用树脂Amberlite IR743的S（1.027）,其中,Cu-MOF-OCH₃对¹⁰B的10/11S>1,UiO-66-NH₂、MIL-101(Cr)-2,3-OH对¹¹B的^11/10S>1。本结果可为系统研究MOFs材料对硼同位素的分离效果提供参考。