Minho Chang

R&D Activities on the Tritium Storage and Delivery System in Korea

Abstract R&D activities on the tritium storage and delivery system include the development of getter beds to increase tritium recovery and delivery performance, the investigation of tritium reaction characteristics with ZrCo metal-hydride, in-bed calorimetry as tritium measurement techniques, and the development of process design technologies for the storage and delivery system such as pump performance test and bed simulator. The current status of the R&D activities on these subjects is addressed in this paper.

EXPERIMENTAL STUDY ON THE DELIVERY RATE AND RECOVERY RATE OF ZrCo HYDRIDE FOR ITER APPLICATION

Abstract To investigate the key design aspects of the storage and delivery system (SDS) bed in ITER, rates of a hydriding, dehydriding and isotope effects on the H/D composition during a rapid delivery were experimentally investigated by using small tube-type reactors with different packing heights. Hydrogen recovery times for a shorter packing-height bed (20~40mm) decreased exponentially with an increasing initial hydrogen pressure, but increased by approximately two orders of a magnitude in a longer packing-height bed (145mm). Dehydriding rate increases exponentially with an increase in the relative heating area per unit weight of ZrCo powder and decreases in the packing-height of ZrCo hydride. Continuous isotopic compositional change inevitably occurs during the entire delivery time due to the known isotope effect in the metal-hydrogen systems. To overcome the isotope effect during a delivery from the SDS beds, an alternative operation method was suggested for the fuel supply from the SDS.

Safety Analysis of a Hydrogen Isotopes Process

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.

Key technologies for tritium storage bed development

Abstract ITER Storage and delivery system (SDS) is a complex assembly system. Lots of individual components including tens of storage beds, a few reactors, multiple transfer pumps, vessels, umpteen instruments & sensors which are interconnected with tubing and fittings in a confined glovebox system are to be installed in the given Tritium Plant area. The most important SDS getter bed will be utilized for absorbing and desorbing of hydrogen isotopes in accordance with the fusion fuel cycle scenario. This paper deals with R&D activities on SDS bed design, especially thermal hydraulic analysis in heat loss aspect, the real-time gas analysis in He-3 collection system, and introductory experimental plans using depleted uranium (DU) getter material for storage of hydrogen isotopes, especially of tritium.

ESTIMATION OF THERMOPHYSICAL PROPERTIES IN MASSIVE ZrCoHx SYSTEM

Abstract Thermophysical properties of the complex metal hydride system such as zirconium cobalt hydride, an intermetallic hydride compound, in a massive state were estimated by introducing a crystal lattice structure in a stepwise formation and applying a mixing rule for each property. Experimental data in rarity in metal hydride system was used to calculate and to correlate the consistency of the mixed thermal and physical properties of the complex atomic structure in a unit cell. As a result, the volume expansion of the ZrCoHx was greatly influenced by the hydrogen content and increased to a maximum range of 36% at ZrCoH3 system, but no meaning in the thermal expansion in engineering concept. In consideration of the heat capacity the temperature effect due to the hydrogen—an interstitial heat quantity—in the metal complex formation was mainly attributed, but not much for the hydrogen content (H/ZrCo ratio). In the temperature range between 200K and 600K the heat capacity of hydrogen atom was taken into account to reveal a sharp discrepancy in its non-hydriding property, especially in the lower temperature range. Atomic hydrogen was expected to behave from a gas to a solid property in heat capacity in the temperature ranges from 600K to 200K.

Hydrogen Brittleness on Welding Part for SDS Bottles

Abstract >> Tritium was attracted with high energy source in neutron fusion energy systems. A number of researchwas performed in tritium storage materials. The Korea was raised storage and delivery systems (SDS) of internationalthermonuclear experimental reactor (ITER) research. However, bottles of SDS would be important because of stability. The bottles have a welding zone, this zone will be vulnerable to hydrogen embrittlement. This zone havea high thermodynamic energy and heat deterioration. Therefore bottles were studied about hydrogen embrittlementto retain stability. The heat treatment of hydrogen was carried under pressure-composition-temperature (PCT) apparatus because of checking at real time. And then, mechanical properties were evaluated by tensile test andhardness test. In results of this study, hydrogen atmosphere condition is very important by tensile test and kineticstest. The samples were evaluated, that is more weak hydrogen pressure, increasing temperature and time. This results could be useful in SDS bottle designs.Key words : Hydrogen embrittlement(수소 취성 ), Hydrogenation(수소화), Tensile test(인장 시험 ), Hardness(경도),Tritium storage(삼중수소저장), SDS(저장 및 공급)

A Numerical Investigation of Hydrogen Absorption Reaction Based on ZrCo for Tritium Storage (I)

In this paper, a three-dimensional hydrogen absorption model is applied to a thin double-layered annulus ZrCo hydride bed and validated against the temperature evolution data measured by Kang et al. 1) The present model reasonably captures the bed temperature evolution behavior and the 99% hydrogen charging time. The equilibrium pressure expression for hydrogen absorption on ZrCo is derived as a function of temperature and the H/M atomic ratio based on the pressure-composition isotherm data given by Konishi et al. 2) In addition, this present model provides multi-dimensional contours such as temperature and H/M atomic ratio in the thin double- layered annulus metal hydride region. This numerical study provides fundamental understanding during hydrogen absorption process and indicates that efficient design of the metal hydride bed is critical to achieve rapid hydrogen charging performance. The present three-dimensional hydrogen absorption model is a useful tool for the optimization of bed design and operating conditions.

Effect of Tritium Storage Vessel and Aluminum Secondary Container on Calorimeter Performance

Abstract A calorimeter was integrated in KEPTL (KEPCO Research Institute Tritium Laboratory) and the various performance tests were performed. The inventory of tritium transport vessels delivered to the ITER tritium plant will be measured by calorimetry. For calorimetry measurement the tritium transport vessel will be inserted in an aluminum secondary container for the tritium leak prevention. The heat capacity and geometry of measuring objects, however, can affect the performance of the calorimeter such as measuring time, sensitivity, etc. In this study, the effect of the heat capacity of the tritium vessel on the performance of the twin cell calorimeter is studied by using JEC and aluminum container which are dummy vessels simulating the tritium decay heat with electric heaters. The average sensitivity in the test with aluminum containers is measured to be 96 μV/mW which is similar that with JEC so it does not depend directly on the heat capacity of the tritium vessel. The aluminum container, however, makes the measuring time increase and the heat flow signal could be unstable in the range of low tritium and high heat capacity like a waste vessel after tritium loading out.

A Numerical Investigation of Hydrogen Desorption Reaction for Tritium Delivery from Tritium Storage Based on ZrCo

In this paper, a three-dimensional hydrogen desorption model is applied to a thin double-layered annulus ZrCo hydride bed and validated against the temperature evolution data measured by Kang et al. 1) The present model reasonably captures the bed temperature evolution behavior and the 90% hydrogen discharging time. In addition, the performance of thin double-layered annulus bed is evaluated by comparing with a simple cylindrical bed using hydrogen desorption model. This study provides multi-dimensional contours such as temperature and H/M atomic ratio in the metal hydride region. This numerical study provides fundamental understanding during hydrogen desorption process and indicates that efficient design of the metal hydride bed is critical to achieve rapid hydrogen discharging performance. The present three-dimensional hydrogen desorption model is a useful tool for the optimization of bed design and operating conditions.