Hydrogen Isotope Separation by Plasma-Chemical Method

Deuterium transfer (exchange) reaction as shown in HDO+H₂=H₂O+HD was studied as a case similar to the tritium transfer reaction as shown in DTO+D₂=D₂O+DT, the first step in tritium isotope separation of the tritiated heavy water DTO. The transfer reaction was plasma-chemically catalyzed by allowing a gas mixture such as H₂O/D₂, D₂O/H₂, H₂O/HDO/H₂ or H₂O/D₂O/HDO/H₂ to flow through an atmospheric pressure discharge zone formed in a reaction chamber, the inner temperature of which was maintained just above 100°C. The plasma-chemical reactions diagnosed by infrared and emission spectroscopy revealed that the mixture underwent instantaneous deuterium transfer reactions as it passed the zone. The effectiveness of the method was demonstrated by high deuterium transfer rate, high separation factor of the transfer and a possibility of miniaturizing the separation facility.     

Hydrogen Isotope Separation by Self-displacement Chromatography Using Palladium Particles

Formation constants of a trivalent f-element, europium, with a series of carboxylates containing neutral donors such as amine and alcohol oxygen were determined by solvent extraction method in 0.1 M NaClO₄ at 25°C. Thirteen carboxylates were adopted for a systematic study of the effect of the functional groups on the complex stabilization. In order to analyze the trend of formation constants, a simple model was developed in which these ligand molecules were considered as composed of a certain number of fragment components of functional groups and chemical bridges each of which differently contributes to the formation constant. All parameter values for electrostatic and steric effects of the fragments were successfully determined by using the formation constants obtained experimentally. The present model is useful for predicting the formation constants of similar multidentate ligands by combining the fragment components and parameter values.     

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.     

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.     

低温制备气相色谱法分离氢同位素

介绍了采用低温制备气相色谱法以Al2O3装填分离柱进行氢同位素分离的装置。研究了氢同位素分离色谱柱(Al2O3分离柱)的制备和操作步骤，并对其分离效果进行了讨论。实验结果表明：经分离、净化后，氘纯度可达99．9％以上。该装置具有结构简单、操作费用低、一次性投资少等优点，在那些对氢同位素纯度要求高，用量小的部门或实验室有良好的应用前景。该装置不仅可用于氢氘分离，还可用于氘氚分离。     

Design and evaluation of gaseous tritium recovery system using commercially available membrane type dehumidifier

In order to realize the planned deuterium plasma experiments using the Large Helical Device, the National Institute for Fusion Science (NIFS) is planning to install a system for tritium recovery from exhaust gas. While adopting typical tritium recovery systems, NIFS has also made plans for the development of a compact reduced-waste recovery system by applying a membrane type dehumidifier. A commercially available membrane dehumidifier was evaluated experimentally for this purpose with the results indicating that such a membrane is feasible for practical application. A small-scale test apparatus having a capacity 1/10 (30 m³(NTP)/h) that of the actual tritium recovery system with the same flow control system was evaluated under actual operating conditions, and the necessary performance for design and operation of the actual system was elucidated.     

Numerical Estimation Method of the Hydrogen Isotope Inventory in the Hydrogen Isotope Separation System for Fusion Reactor

In the fuel cycle system of the ITER, a large fraction of tritium inventory is expected to be in the cryogenic distillation columns of the hydrogen isotope separation system (ISS). Therefore, the numerical estimation method of hydrogen isotopes inventory in the ISS with high precision is strongly required from safety point of view. Two series of experiments were performed to establish the numerical estimation method of the overall hydrogen isotope inventory in the ISS at steady state using ITER-scale large cryogenic distillation columns at the Tritium Systems Test Assembly in the Los Alamos National Laboratory under the US-Japan collaboration on tritium safety engineering. As a result of experiments, it was confirmed that the hydrogen isotope inventory in a cryogenic distillation column was estimated by the numerical estimation method proposed in this work with enough high precision from the engineering point of view, and it was proved that this method was applied for the ITER-scale cryogenic distillation columns. The precision of this estimation method was found to be almost independent on the composition profile in columns, and especially the liquid holdup ratio of deuterium to the volume of the column was less influential in the inner diameter of the packed section. In addition, the gaseous inventory in an ITER-scale cryogenic distillation column was found to have considerable impact on the total amount of holdup of the column.     

氢-水同位素交换分离因子理论计算

采用量子化学从头计算法计算得到氢水同位素交换体系HDg／H2O1和DTg／D2O1在O．1MPa、283．2～373．2K下的气相反应平衡常数，并根据相应同位素水的饱和蒸气压求得气液交换过程的分离因子，得出了两种氢水同位素交换体系总反应分离因子。     

Tritium Isotope Separation by CO2 Laser Irradiation at Dry Ice Temperature

A computational method based on boundary element method (BEM) has been developed to analyze transient temperature distribution in a three-dimensional solid having non-linear boundary condition (for example boiling or thermal radiation). To obtain high numerical accuracy, the heat transfer coefficient which depends on the surface temperature was approximated as a linear combination of interpolation functions with respect to time and analytical time integration of the non-linear term included in boundary integral equation was made.

To investigate feasibility of the present method, it was applied to calculations of the temperature distribution in an infinite flat plate cooled on one side. The heat transfer co-efficient of cooling surface was in proportion to n-th power of the surface temperature. Results are (1) the method has given a stable solution for non-linear boundary value problems such as conventional BEM could not solve, (2) it has given an accurate solution for large time increment except for first time step, and (3) an optimal relaxation factor decreases with strength of non-linearity of the heat transfer coefficient.

Applying the method to thermal analysis of limiter and divertor plate installed in a fusion test facility and fusion reactor respectively, availability of the method has been confirmed.     

Lithium Isotope Separation by Displacement Chromatography Using Cryptand Resin

This paper summarizes results of sensitivity analysis of a generic geologic disposal system for HLW, using a GSRW code and an automated sensitivity analysis methodology based on the Differential Algebra. The results of sensitivity analyses indicate that parameters related to a homogeneous rock surrounding a disposal facility have higher sensitivities to the performance measure analyzed here than those of a fractured zone and engineered barriers.

This methodology permits sensitivity analyses of a single parameter with changing values of other parameters simultaneously, and thus gives quantitative information on the interrelation- ship between the parameters: the parameters for engineered barriers are generally insensitive to the output, while they are somewhat sensitive to the output only in a case of the low solubility condition. The methodology also provides technical Information which might be basis for the optimization of design of the disposal facility.     

Computer Analysis on Steady State Separation Characteristics of Hydrogen Isotope Separation System by Cryogenic Distillation

A computer code is developed for effective and exact simulation of cryogenic distillation columns. The simulation model incorporates the differences of latent heat of vaporization among the six molecular species, pressure drop, decay heat of tritium, heat transfer through the column wall, Raoult's law deviation of the solutions of hydrogen isotopes, multiple feeds and multiple sidestreams. The calculational procedure developed by Tomich for general equilibrium stage processes is further modified to match this complicated simulation model.

A computer simulation study is performed for the typical cryogenic distillation column cascade and separation characteristics of each column are clarified. The effects of pressure drop are found not significant. If the tritium concentration in the column is considerably high, the lower performance caused by decay heat effects cannot be neglected any longer. Increase of the reflux ratio or refrigeration of the stripping section, is required for improvement.

The present study provides a great help to development of exact simulation models and simulation procedures of cryogenic distillation columns.     

Intensity and Pressure Effects in CO2 Laser Isotope Separation of Tritium Photolysis of CF3CTCIF with 2-ns Pulses

Albedo-Sn method was developed to predict the angular flux near the coupling boundary in the bootstrap method, using the energy-and-angle dependent double differential albedo boundary condition. In order to verify the applicability of the method to the reactor shielding design, two types of shielding problem have been analyzed. First, the neutron skyshine dose rates measured at the YAYOI reactor in University of Tokyo are predicted within an accuracy of 20%. It is also found that the neutron spectrum in the air-over-ground is much affected by albedo reflection from the ground and is reproduced well by the albedo-Sn method. Second, as for the neutron streaming through a sodium pipe chase-way, the albedo-Sn calculation saves a computer time and gives the results which agree with those by the reference Sn calculation.     

化学交换反应法分离硼同位素的数学模型

采用化学交换反应法,针对三氟化硼-苯甲醚分离体系,研究了硼同位素分离生产过程的特点,建立了交换精馏塔的稳态数学模型,并利用Matlab程序进行模型求解,得到了不同分离要求和操作条件对交换精馏塔理论塔板数的影响.当增大所需同位素丰度或改变分离温度以及回流比时,都会使得理论塔板数增加或减少.该数学模型可以指导工艺设备的改进和优化,为下一步的放大和操作过程提供了理论依据.     

Measurement of HETP of SUS Dixon Ring and Porcelain Packing in Small-Scale Water Distillation Column for H2O-HTO Isotope Separation

Series of water distillations in a total reflux mode have been performed in a 100cm height column of 1.6cm I. D. in order to measure values of HETP for various packings, that is, one brass or three SUS Dixon rings and three porcelain packings. The HETP were measured by changing the vapor flow rate within the column. The SUS Dixon ring of 1.5 mm diameter and the porcelain packing of 1.2 mm O. D. had a small HETP (～5cm), but could not meet a large vapor flow rate because of a large pressure drop. The SUS Dixon ring of 6.0 mm diameter had a small HETP (～6cm) in the vapor flow rate under 2g/min, but the HETP value increased with increasing the vapor flow rate. The pressure drop for the ring, however, was almost constant in the range of these measurements.     

氢-苯乙烯体系中氢-氚同位素交换反应的热力学研究

采用6-311G全电子基函数和B3p86方法对聚苯乙烯-二乙烯基苯(polystyrene-divinylbenzene,SDB)单体之一的苯乙烯分子结构进行优化计算.根据热力学原理,计算得到SDB官能团分子氢氚取代反应在不同温度下的标准生成自由能函变、反应平衡常数及氚气和氢气的反应平衡压力比.结果表明,温度的升高不利于氢氚取代反应T2(g) SDB(H2)(s)→H2(g) SDB(T2)(s)正向进行,这与Pt/SDB疏水催化剂在氢-水同位素交换的催化反应实验过程中的氢氚取代研究结论一致.     

Reduced partition function ratios of hydrogen species adsorbed on platinum cluster Pt19 studied by density functional theory

Geometry optimization and estimation of H/D reduced partition function ratios (RPFRs) of Pt₁₉–H, Pt₁₉–H⁺, Pt₁₉–H₂, and Pt₁₉–H₂⁺ models of hydrogen species adsorbed on surfaces of metallic platinum particles, were carried out based on the density functional theory. Two types of optimized structures were obtained for Pt₁₉–H and Pt₁₉–H⁺, and three for Pt₁₉–H₂ and Pt₁₉–H₂⁺. Stabilization energy consideration suggested that the most probable structure for Pt₁₉–H and Pt₁₉–H⁺ is the one in which H/H⁺ is bonded to a Pt atom, and that for Pt₁₉–H₂ and Pt₁₉–H₂⁺ is the one in which two H/H⁺s are bonded to two adjacent Pt atoms with no direct bonding between the two H/H⁺s. The value of RPFR obtained for those structures ranged from 3.9303 to 4.4014 at 25 °C. Interaction between two adjacent H–Pt bonds seems to slightly enhance the mutual RPFR values.     

Effect of Flow Rate on Height Equivalent to a Theoretical Plate for Lithium Isotope Separation with Displacement Chromatography

A series of experiments of Li isotope separation with displacement chromatography using a highly porous resin were performed under several flow rates from 0.1 to 20 cm³/min. The flow rates were equivalent to a speed of a moving boundary of 0.0012 to 0.26cm/s. In evaluating Height Equivalent to a Theoretical Plate, HETP, as well as separation factor which indicate separative performance of chromatographic system, we developed a new relationship between HETP and a profile of ⁶Li mole fraction in the effluent with a mathematical model taking account of a mixing in a free space at the column outlet and in the fractionated samples. The values of separation factor and HETP of each experiment were simultaneously determined by the developed relation. The obtained values of the separation factor agreed with those evaluated by the frontal analysis method within the range of the experimental error. The obtained value of HETP increased with the flow rate in the range of the present experiments. It was suggested that diffusion of Li ion in particles as well as convective mixing of the solution played a significant role on determination of HETP.     

水-氢交换氢同位素体系HD/H_2O、DT/D_2O和HT/H_2O分离性能模拟研究

计算模拟应用于氢同位素分离领域,能够方便、快捷地进行工艺条件分析。本工作采用数值模拟的方法对比研究了水-氢催化交换过程中HD/H_2O、DT/D2O和HT/H_2O三种氢同位素体系的分离性能。研究表明:在一定工艺条件下,三种体系均在操作温度为343K时达到最大的分离效果;随着气液比从1.0增大到3.0,最优操作温度均从343K降低到323K,但是在此过程中,HT/H_2O体系的分离效果受温度的影响较小一些;在达到最大分离效果的目标下,HT/H_2O体系需要的理论塔板数比HD/H_2O和DT/D2O体系少,同时,在优化的工艺条件下,三体系气相中氢同位素浓度在交换柱内分布曲线存在一定的差异。     

氢同位素氘从气相到液相的催化交换实验研究

采用Pt SDB疏水催化剂与亲水填料按1∶4混装进行氘从气相到液相的催化交换实验,研究影响传质单元数及氘转化率的因素。结果表明:为获得较大的传质单元数,需选择合适的操作温度及交换气流速;液体流量增加,转化率提高,但液体流量达到一定程度时,氘转化率几乎不再变化;催化柱长度对氘转化率有较大影响,交换气流速2 m3/h、液体流量1~2 kg/h、45 ℃时,4 m柱长下的氘转化率达到90%。