Hydrogen Isotope Separation System Research Articles

Hydrogen isotope inventory evaluation of hydrogen isotopes separation system of CFETR using Aspen Plus simulator

The tritium plant needs to recover unburned deuterium and tritium for recycling to achieve tritium self-sufficiency. The tritium recovered by the water detritiation system (WDS) contains a large amount of protium. High purity deuterium (D) and tritium (T) are required as fuel for fusion reactor while hydrogen (H) always exists as an impurity of the fuel. Therefore, a hydrogen isotope separation system (ISS) is essential for fuel cycle in fusion reactor. ISS separates the recovered H, D, T, and removes the impurity protium (H) to obtain high-purity fuel deuterium and tritium. In this paper, two hydrogen isotope separation systems for the inner fuel cycle system and the outer fuel cycle system of CFETR (China Fusion Engineering Test Reactor) are respectively established according to the disparity in tritium concentration of hydrogen isotopes gas. The tritium inventory in the ISS is expected to be very large, evaluating the tritium inventory of ISS facilitates the evaluation of the minimum initial startup tritium inventory for the operation of the fusion reactor. The chemical simulation software Aspen Plus is used to simulate the separation process of ISS. The purity of products and the distribution of hydrogen isotopes in each distillation column are obtained. Based on the simulated data, the tritium inventory in each distillation column is calculated.

Dynamic Optimization Study for Cryogenic Distillation in Hydrogen Isotope Separation System

This paper presents a dynamic optimization study on a cryogenic distillation unit in hydrogen isotope separation system. A packed distillation column with an equilibrator is considered. The packed column was modeled as a theoretical equilibrium-based stage column. The equilibrator was placed to enhance separation performance. An optimal control problem was formulated to minimize the tritium holdup under two product quality constraints, in a situation where feed flowrate is periodically fluctuated. An optimal control policy was obtained for two manipulating variables, namely distillate flowrate and reboiler heat duty. The optimal control policy was analyzed by examining the operating variable profiles of the column.

Design study of a cryogenic distillation column for hydrogen isotope separation system

This paper presents a design study of a cryogenic distillation column for hydrogen isotope separation. The column was modeled as a theoretical equilibrium-based stage column. Thermodynamic properties were evaluated with the Peng–Robinson Twu equation of state model. The liquid holdup and pressure drop of each theoretical stage were modeled with a general packed column model. The models were implemented in an equation-oriented optimization framework. The effects of parameters such as the number of theoretical stages, feed location, diameter, flow rate of the distillate, and condenser duty on the tritium inventory, total pressure drop, and product quality were investigated. An optimal design that minimizes the total amount of tritium in the liquid holdup under a tritium product quality constraint and non-flooding constraints is presented.

Dynamic optimization of cryogenic distillation operation for hydrogen isotope separation in fusion power plant

Stable operation of a hydrogen isotope separation system is one of the most important issues in the sustainable operation of fusion power plants. Owing to the present limitation in retention time of fusion reaction, fusion reactors are run in repeated batch operations, causing large fluctuating flows in the system. Hence, to reliably produce required products, counteractive operational strategies must be devised. To this end, we perform dynamic optimization in this paper to derive an optimal control policy that can minimize the tritium inventory and satisfy the product quality specifications. In addition, a rigorous dynamic model for packed columns is developed to simulate realistic behaviors of cryogenic distillation. We demonstrate that the optimization results yield vital operational strategies, such as operation mode switching, without any expertise provided.

New method for calibration of a quadrupole mass spectrometer for hydrogen isotopes measurements

Quantitative analysis of hydrogen isotopes is an essential problem when it comes to accurately determine the performance of ITER hydrogen isotope separation system, or in case of the purity of tritium gas for injection into the Tokamak, to know the level of impurities, in terms of protium and deuterium (H, D).Mass spectrometry is a reliable method to accurately measure low or high concentrations of hydrogen isotopes (H and D) in various gas mixtures.Due to the interferences caused by the triatomic ions formed in the ion source as a result of the interactions between ions and neutral molecules, corrections must be applied in order to get accurate results.In this paper, a new method for calibration of a quadrupole mass spectrometer for hydrogen isotopes (protium and deuterium) is presented, taking into account the contributions and corrections due to the interferences caused by the triatomic ions at the interest m/z ratios. Also, the uncertainty of the measurement and the detection limit of the method are determined.In order to verify the validity of the method, an intercomparison between the results obtained using Fourier-Transform Infrared Spectroscopy method (a FTIR spectrometer) and the quadrupole mass spectrometer (QMS) was performed for the quantitative analysis of hydrogen isotopes.

Exploiting Diffusion Barrier and Chemical Affinity of Metal-Organic Frameworks for Efficient Hydrogen Isotope Separation.

Deuterium plays a pivotal role in industrial and scientific research, and is irreplaceable for various applications such as isotope tracing, neutron moderation, and neutron scattering. In addition, deuterium is a key energy source for fusion reactions. Thus, the isolation of deuterium from a physico-chemically almost identical isotopic mixture is a seminal challenge in modern separation technology. However, current commercial approaches suffer from extremely low separation efficiency (i.e., cryogenic distillation, selectivity of 1.5 at 24 K), requiring a cost-effective and large-scale separation technique. Herein, we report a highly effective hydrogen isotope separation system based on metal-organic frameworks (MOFs) having the highest reported separation factor as high as ∼26 at 77 K by maximizing synergistic effects of the chemical affinity quantum sieving (CAQS) and kinetic quantum sieving (KQS). For this purpose, the MOF-74 system having high hydrogen adsorption enthalpies due to strong open metal sites is chosen for CAQS functionality, and imidazole molecules (IM) are employed to the system for enhancing the KQS effect. To the best of our knowledge, this work is not only the first attempt to implement two quantum sieving effects, KQS and CAQS, in one system, but also provides experimental validation of the utility of this system for practical industrial usage by isolating high-purity D2 through direct selective separation studies using 1:1 D2/H2 mixtures.

Hydrogen Isotope Separation By Using Alkaline Fuel Cell

Introduction The heavy hydrogen isotopes, deuterium (D) and tritium (T) are important materials in the field of nuclear energy. Particularly in recent years, development of new effective separation method is required for the water contaminated by the T. Every day the enormous volume is accumulating in Fukushima Daiichi Nuclear Power Plant. The water electrolysis, which is the industrially most general separation method, has disadvantage that consume energy is tremendous. To solve this point, we have investigated novel hydrogen isotope separation system named Combined Electrolysis Fuel Cell (CEFC) [1]. In this system, hydrogen and oxygen produced by electrolysis is used for power generation in fuel cell. From this, we can save energy and get further isotope effect by electrochemical reaction in fuel cell. Actually we reported that the D isotope was enriched in water phase by fuel cells with anion or cation conducting polymer [2, 3]. Here, we newly focused on another type of fuel cell, Alkaline Fuel Cell (AFC), and investigated the separation mechanism by several electrochemical methods. Experimental The anode was Ru catalyst supported by carbon and the cathode was Pt one. The electrolyte was 30 wt.% KOH solution. Pure H2­­ or D2 gas was supplied to anode and air was did to cathode. The reference electrode was Hg/HgO. Linear sweep amperometry was measured at the scan rate of 20 mA/sec until the cell voltage reached 0.4 V. Simultaneously electrochemical impedance spectroscopy (EIS) was carried out by frequency analyzer. The frequency range was from 0.1 Hz to 1 x 104 Hz. The experimental temperature was 50 ºC. 3．Results Figure 1 shows the cell voltage-current curves of AFC. The same values of cell voltage at 0 A did not clearly demonstrate that the equilibrium potential of hydrogen oxidation reaction depended on the isotopes. The activation overvoltage, which can be detected as the voltage drop when the current was applied, was about 0.2 V for both gases. On the one hand, the cell voltage decreased linearly until the current reached 1400 mA when H2 gas was used. On the other hand, the voltage of D2 result was remarkably fallen at 1160 mA. The difference of the cell voltage was mainly attributed to the anode potential. This result suggested that the H2 gas transportation in the gas diffusion layer was faster than that of D2 probably. In the meeting, we report the separation factor of the D in a ddition to the EIS results. [1] H. Matsushima, T. Nohira, T. Kitabata, Y. Ito, Energy. 30 (2005) 2413. [2] S. Shibuya, H. Matsushima, M. Ueda, J. Electrochem. Soc. 163 (2016) F704 [3] R. Ogawa, H. Matsushima, M. Ueda, Electrochem. Commun. 70 (2016) 5. Figure 1

The Laboratory for Laser Energetics’ Hydrogen Isotope Separation System

The University of Rochester’s Laboratory for Laser Energetics has commissioned a hydrogen Isotope Separation System (ISS). The ISS uses two columns—palladium on kieselguhr and molecular sieve—that act in a complementary manner to separate the hydrogen species by mass. The 4-sL per day throughput system is compact and has no moving parts. The columns and the attendant gas storage and handling subsystems are housed in a 0.8-m3 glovebox. The glovebox uses a helium cover gas that is continuously processed to extract oxygen and water vapor that permeates through the glovebox gloves and any tritium that is released while attaching or detaching vessels to add feedstock to or drawing product from the system. The isotopic separation process is automated and does not require manual intervention. A total of 315TBq of tritium was extracted from 23.6sL of hydrogen with tritium purities reaching 99.5%. Deuterium was the sole residual component in the processed gas. Raffinate contained 0.2TBq of activity was captured for reprocessing. The total emission from the system to the environment was 0.4GBq over three weeks.

Software development for the simulation and design of the cryogenic distillation cascade used for hydrogen isotope separation

The hydrogen isotope separation system (ISS) based on cryogenic distillation is one of the key systems of the fuel cycle of a fusion reactor. Similar with ITER ISS in a Water Detritiation Facility for a CANDU reactor, one of the main systems is cryogenic distillation. The developments on the CANDU water detritiation systems have shown that a cascade of four cryogenic distillation columns is required in order to achieve the required decontamination factor of the heavy water and a tritium enrichment up to 99.9%.This paper aims to present the results of the design and simulation activities in support to the development of the Cernavoda Tritium Removal Facility (CTRF). Beside the main features of software developed “in house”, an introduction to the main relevant issues of a CANDU tritium removal facility for the ITER ISS is provided as well. Based on the input data (e.g. the flow rates, the composition of the gas supplied into the cryogenic distillation cascade, pressure drop along the column, liquid inventory) the simulation provides the distribution of all the molecular species involved along each cryogenic distillation column and also the temperature profile along the columns.The approach for the static and dynamic simulation of a cryogenic distillation process is based on theoretical plates model and the calculations are performed incrementally plate by plate.

Direct Delivery of Hydrogen Isotopes from a DU Hydride Bed

A tritium plant for nuclear fusion power plants consists of an SDS (Storage and Delivery System), an ISS (Hydrogen Isotope Separation System), a TEP (Tokamak Exhaust Processing system), and an ANS (tritium plant Analytical System). Korea has been developing an SDS. The main purpose of this tritium storage and delivery system is to store and supply the D-T gas needed for DT plasma operation and to provide the necessary infrastructure for short- and long-term storage of large amounts of tritium. We have been developing tritium storage beds for the SDS.The primary role of the metal hydride beds in the SDS is to store and supply D-T fuel during DT plasma operation. ZrCo and depleted uranium (DU) have been extensively studied. Compared to the use of ZrCo, which is disproportionate at temperatures of higher than 350°C, DU hydride can be heated up to very high temperatures sufficient to pump hydrogen isotopes without using gas compressors. Our experimental apparatus used to test the experimental DU bed consists of a tank that stores and measures the hydrogen, and a DU bed used for the hydriding/dehydriding of hydrogen. Our DU bed is a horizontal double-cylinder type with sintered metal filters. The bed is composed of primary and secondary vessels. The primary vessel contains a DU, and a vacuum layer is formed between the primary and secondary vessels. In this study, we present our recent experimental results on the direct delivery of hydrogen isotopes from a DU hydride bed. We also present the effect of the initial bed temperature and impurity gas on the hydriding rates.

수소동위원소 저장용 ZrCo용기의 급속 냉각 성능 평가

The nuclear fuel cycle plant is composed of various subsystems such as a fuel storage and delivery system (SDS), a tokamak exhaust processing system, a hydrogen isotope separation system, and a tritium plant analytical system. Korea is sharing in the construction of the International Thermonuclear Experimental Reactor (ITER) fuel cycle plant with the EU, Japan, and the US, and is responsible for the development and supply of the SDS. Hydrogen isotopes are the main fuel for nuclear fusion reactors. Metal hydrides offer a safe and convenient method for hydrogen isotope storage. The storage of hydrogen isotopes is carried out by absorption and desorption in a metal hydride bed. These reactions require heat removal and supply respectively. Accordingly, the rapid storage and delivery of hydrogen isotopes are enabled by a rapid cooling and heating of the metal hydride bed. In this study, we designed and manufactured a vertical-type hydrogen isotope storage bed, which is used to enhance the cooling performance. We present the experimental details of the cooling performances of the bed using various cooling parameters. We also present the modeling results to estimate the heat transport phenomena. We compared the cooling performance of the bed by testing different cooling modes, such as an isolation mode, a natural convection mode, and an outer jacket helium circulation mode. We found that helium circulation mode is the most effective which was confirmed in our model calculations. Thus we can expect a more efficient bed design by employing a forced helium circulation method for new beds.

수소동위원소 공정 안전해석

A nuclear fusion fuel cycle plant is composed of various subsystems such as a hydrogen isotope storage and delivery system, a tokamak exhaust processing system, and a hydrogen isotope separation system. Korea shares in the construction of the International Thermonuclear Experimental Reactor fuel cycle plant with the EU, Japan and US, and is responsible for the development and supply of the storage and delivery system. We thus present details on the hydrogen isotope process safety. The main safety analysis procedure is to use a hazard and operability study. Nine segments were studied how the plant might deviate from its design purpose. We present a detailed description of the process, examine every part of it to determine how deviations from the design intent can occur and decide whether these deviations can give rise to hazards. We determine possible causes and note protective systems, evaluate the consequences of the deviation, and recommend actions to achieve our safety goal.

Korea’s Activities for the Development of ITER Tritium Storage and Delivery Systems

The ITER fuel cycle plant is composed of various subsystems such as a long term tritium storage system (LTS), a fuel storage and delivery system (SDS), a tokamak exhaust processing system, a hydrogen isotope separation system, and a tritium plant analytical system. Korea shares in the construction of the ITER fuel cycle plant with the EU, Japan and US, and is responsible for the development and supply of the SDS and LTS. The authors thus present details on the development status of the tritium transport container, the long term tritium storage beds, the short-term delivery system T2, DT, and the D2 storage beds, the calorimetry system, and the associated He-3 recovery loop, the over pressure protection systems, and the gas analysis manifold connected to the tritium plant’s analytical systems.

Disproportionation Characteristics of a Zirconium-Cobalt Hydride Bed under ITER Operating Conditions

Quantitative assessment of a disproportionation in the ZrCo-hydrogen system under ITER-relevant operating conditions was performed by means of experimental tests and a theoretical calculation. In the static temperature experiments with equilibrium hydrogen pressures, a 10% disproportionation of ZrCoHx (x = 2.0 and 2.5) was observed in 5.5 h at 415° (~78 kPa), 9 h at 400° (~72 kPa), 172 h at 380° (~51 kPa), and 1626 h at 350° (~28 kPa). An experimental formula [log τ = 17 268/T (K) - 25.814, where τ is the reaction time (day) of 10% disproportionation] was derived from these experiments. Experiments with a temperature cycling of up to 125 cycles (from room temperature to 350 to 360°) proved that no enhancement of a disproportionation occurs in the ZrCoHx (1.7 < x ≤ 2.0). Typical operation conditions of the ZrCo hydride bed for the D-T gas storage delivery system were proposed based on the ITER FDR 2000 plasma operation scenarios. The disproportionation rate estimated conservatively by the theoretical model indicates that a disproportionation in the ITER basic performance phase can be reduced by <4% even when there is a direct supply from the fuel storage and delivery system beds for all the D-T pulses and by <0.1% when the supply is from the hydrogen isotope separation system.

Operation Scenarios and Requirements for Fuel Processing in Future Fusion Reactor Facilities

Operability and operation scenario of hydrogen Isotope Separation System (ISS) for ITER and a demo reactor are checked and examined based on the information in the ITER documents. It has been confirmed that the current ISS design well covers the operational requirements of the designated operation modes and other anticipated operations. However, some operation modes using rich deuterium fuel will require additional tritium inventory in the system (not only for ISS but the storage system in some cases) and make duration time between the operations longer. Operation scenario of ISS for a demo reactor will be quite simple, but the process capacity required being associated with de-tritiation of coolant water become excessively large without any countermeasure to control/reduce tritium permeation in the bleeding blanket operated at a temperature much higher than that of ITER.

A New Kind of Column Materials for Gas Chromatographic Hydrogen Isotope Separation

A new kind of materials that can be applied to a gas chromatographic hydrogen isotope separation system was developed to reduce the amount of Pd-Pt alloy required for making the column and to improve the separation efficiency. Pd and Pt were deposited on α-Al2O3 powder by using a barrel sputtering system. Prepared sample powder was characterized from surface morphology, element distributions on the surface, composition and crystallinity. The characterization showed that a uniform layer of Pd-Pt alloy with expected composition was formed on Al2O3 particles. The crystallinity, however, was poor, but improved after annealing at 1073 K for 2 hours. The hydrogen absorbing behavior was also improved by the annealing. A separation column was prepared from the annealed powder and was subjected to experiments on hydrogen isotope separation. The column of annealed powder gave considerably good separation efficiency around room temperature, in spite that only 0.35 g of Pd-Pt was used for the column. The amount of Pd-Pt alloy used here should be compared to previous results, where 1.5 g of Pd-Pt powder was required for high separation efficiency. The new material was quite effective to reduce the amount of Pd-Pt alloy without compromising the separation efficiency and can give further improvement.

H-D-T cryogenic distillation experiments at TPL/JAERI in support of ITER

The hydrogen isotope separation system (ISS) using cryogenic distillation method is one of the key systems in a fuel cycle loop of a fusion reactor. The ISS for the International Thermonuclear Experimental Reactor (ITER), is characterized by its required flexibility for the variability of feed composition, which is not considered in the existing industrial distillation columns, so that the development of evaluation method of dynamic behavior, which is the base for the establishment of ISS control system, is essential as original technology. At the Tritium Process Laboratory in Japan Atomic Energy Research Institute (TPL/JAERI), H-D-T cryogenic distillation experiments have been carried out to acquire the systematic data for the design of the ISS for the ITER. The value of height equivalent to a theoretical plate (HETP) was estimated to be 5 cm by the results of present experiments and it was adopted in the ITER–ISS design. The in situ, multi-points and reliable high-speed gas analytical system with Laser Raman spectroscopy was successfully demonstrated in the experiment to analyze the hydrogen isotopes of H 2-HD-HT-D 2-DT-T 2 within 1 min with the analysis limit of 1000 ppm, which indicates that this system enables fine control of the ISS. The reliability of this system was also proved through its use without any mechanical trouble for more than 2 years. The analysis codes were developed and improved through the experiments, and it was succeeded to simulate the dynamic behavior of the distillation column. Through a series of the ISS experiments at the TPL/JAERI, effective design and effective operation of the ISS became to be possible.

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.

Study on Sudden Loss of Cryogenic Coolant Accident Happened in the Hydrogen Isotope Separation System for Fusion Reactor

ABSTRACTSudden loss of cryogenic helium coolant accident (ISS-LOCA) in the cryogenic distillation columns for the hydrogen isotope separation system (ISS) is one of the worst situations because it leads the evaporation of liquid hydrogen in the column. From this background, an intended ISS-LOCA test was conducted with an actual ITER-scale cryogenic distillation column. Sudden increase of internal pressure was not observed and enough time is found to recover the hydrogen isotope into a storage system if vacuum insulation is maintained and reboiler heaters are turned off immediately. In off-normal conditions, the rapid recovery of hydrogen in the column by an empty hydrogen storage bed is a reasonable hydrogen recovery scenario. Validity of the hydrogen recovery scenario was proved by a demonstration test.

A Design Study of Advanced Hydrogen Isotope Separation System for ITER

A preliminary improved design study of the cryogenic distillation hydrogen isotope separation system (ISS) for the fuel cycle of the ITER-FEAT, a fusion experimental reactor, was carried out based on the substantial reduction of hydrogen flow to the ISS resulting from the scale reduction from the former design for the FDR-ITER. In this study, a four-column cascade was proposed considering the 450 seconds burn / 1350 seconds dwell operation scenario of ITER-FEAT instead of the present five-column cascade design of the FDR-ITER. This proposed cascade is found to be effective in all operation phases. The impact of the optional 3000 seconds burn / 9000 seconds dwell operation scenario on the present design is also discussed in this paper. Tritium concentration in the released hydrogen stream into environment must always be controlled to be lower than the regulation limit for stack release, and the two-column system for treatment of this flow is found to be effective for meeting this requirement.