• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.1975-1988
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• 2024

It is important to maintain cladding integrity in spent nuclear fuel management. This study proposes a numerical analysis method to evaluate the fracture resistance of irradiated zirconium alloy cladding under pinch load known to cause Mode-III failure. The mechanical behavior and fracture of the cladding under pinch loading can be evaluated by a Ring Compression Test (RCT). To simulate the fracture of hydride precipitates, zirconium matrix, and Zr/hydride interfaces under the stress field generated by RCT, a micro-structure crack propagation simulation method based on Continuum Damage Mechanics (CDM) has been proposed. Our RCT simulation model was constructed from microscopic images of irradiated cladding. In this study, we developed an automated process to generate a pixel-based finite element model by separating the hydride precipitates, zirconium matrix, and interfaces using an image segmentation method. The appropriate element size was selected to ensure the efficiency and accuracy of a crack propagation simulation. The load-displacement curves and strain energies from RCT were compared and analyzed with the simulation results of different element sizes. The finalized RCT simulation model can be used to establish the failure criterion of fuel rods under pinch loading. The advantages and limitations of the proposed method are fully discussed here.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.3
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• pp.363-371
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• 2011

In this paper, a three-dimensional hydrogen desorption model is developed to precisely study the hydrogen desorption kinetics and resultant heat and mass transport phenomena in metal hydride hydrogen storage vessels. The metal hydride hydrogen desorption model, i.e. governed by the conservation of mass, momentum, and thermal energy is first experimentally validated against the temperature evolution data measured on a cylindrical $LaNi_5$ metal hydride vessel. The equilibrium pressure used for hydrogen desorption simulations is derived as a function of H/M atomic ratio and temperature based on the experimental data in the literature. The numerical simulation results agree well with experimental data and the 3D desorption model successfully captures key experimental trends during hydrogen desorption process. Both the simulation and experiment display an initial sharp decrease in the temperature mainly caused by relatively slow heat supply rate from the vessel external wall. On the other hand, the effect of heat supply becomes influential at the latter stages, leading to smooth increase in the vessel temperature in both simulation and experiment. This numerical study provides the fundamental understanding of detailed heat and mass transfer phenomena during hydrogen desorption process and further indicates that efficient design of storage vessel and heating system is critical to achieve fast hydrogen discharging performance.

• Analytical Science and Technology
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• v.9 no.1
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• pp.26-34
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• 1996

A method to determine the trace amount of Se and Bi in the scalp hair using the hydride generation inductively coupled plasma atomic emmission spectrometry was studied. The optimum operation conditions of ICP for hydride generation are 0.6~0.8L/min for the carrier gas flow rate, and 6mm above the induction coil for the observation height. Hydrochloric acid concentrations for the optimum hydride generation conditions were greater than 1.5M when 2.5% $NaBH_4$ and NaOH were used, and greater than 0.5M when 2.5% $NaBH_4$ and 0.1% NaOH were used. Severe interference effects are observed from transition metals such as Cu and Ni, and they could be circumvented by the coprecipitation with lanthanum hydroxide.

• Analytical Science and Technology
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• v.14 no.1
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• pp.34-43
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• 2001

The present work is aimed to evaluate the conditions of the hydride generation (HG) for germanium analysis by inductively coupled plasma (ICP)-atomic emission spectrometry (AES). Twelve different kinds of acids were used such as phosphoric, hydrochloric, nitric, sulfuric, perchloric, boric, tartaric, malic, oxalic, tannic, citric, and acetic acid. It was found that phosphoric acid yielded the maximum efficiency of hydride generation. Also, efficient hydride generation was obtined with the buffer solutions containing phosphate ions over a wide range of pH. In addition, in the presence of phosphoric acid the interference caused by metals was suppressed in the hydride generation of germanium. As the concentrations of a reducing agent and a stabilizing increased the hydride generation efficiency and the acid concentration proviaing the maximum intensity were increased. By using an analytical method developed in this study, the contents of germanium in water and rock samples were determined. The detection limit of germanium in the presence of phosphoric acid was $0.03{\mu}g/L$.

• Analytical Science and Technology
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• v.14 no.5
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• pp.410-415
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• 2001

An analytical method has been developed which determines lead in steel samples by inductively coupled plasma mass spectrometry (ICP-MS) with sample introduction by the hydride generation. The lead hydride is not stable and requires and oxidant for the oxidation into metastable Pb(IV) before reduction to $PbH_4$ with $NaBH_4$. A study was carried out to find and optimum lead hydride generation condition for a sample solution with more than $1000{\mu}g/mL$ Fe matrix. $K_2Cr_2O_7$ was found to work as an efficient oxidant when more than $10{\mu}g/mL$ Fe matrix was present. Lactic acid was used with the oxidant as a complexing agent of the metastable Pb(IV) to enhance sensitivity. Optimum concentrations of the sample acidity, oxidant and lactic acid were different depending on the matrix concentration. The isotope dilution method was employed for the quantitation of lead. The determined Pb concentrations of the NIST steel SRM 361 and 362 were in good agreement with the certified values within the uncertainty range.

• Journal of the Korean Chemical Society
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• v.48 no.6
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• pp.583-589
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• 2004

In a stream of aqueous sample, trace arsenic ions were quantitatively coprecipitated and detected in ICP-AES through hydride generation. In was used as a coprecipitating reagent. The precipitate was collected on a filter and dissolved by HCl. The eluted As was sent into the reaction coil to generate hydrides and analyzed by ICP. With optimal conditions, and with a sample of 0.3 mL, an enrichment of 70 was obtained with the sampling speed of 10/hr. When compared with coprecipitation and hydride generation technique, the sensitivity was increased by 7 and 10 times, respectively. The limit of detection limit$(3{\sigma})$ was 0.020 ${\mu}g\;L^{-1}$ and the precision was 7-10%. Separation of $As^{3+}\;and\;As^{5+}$ were possible using citric acid in hydride generation.

• Bulletin of the Korean Chemical Society
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• v.10 no.4
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• pp.382-388
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• 1989

The approximate rates and stoichiometry of the reaction of excess potassium tri-sec-butylborohydride ($K_s-Bu_3BH$) with selected organic compounds containing representative functional groups were determined under the standard conditions (0$^{\circ}C$, THF) in order to define the characteristics of the reagent for selective reductions. Primary alcohols evolve hydrogen in 1 h, but secondary and tertiary alcohols and amines are inert to this reagent. On the other hand, phenols and thiols evolve hydrogen rapidly. Aldehydes and ketones are reduced rapidly and quantitatively to the corresponding alcohols. Reduction of norcamphor gives 99.3% endo- and 0.7% exo-isomer of norboneols. The reagent rapidly reduces cinnamaldehyde to the cinamyl alcohol stage and shows no further uptake of hydride. p-Benzoquinone takes up one hydride rapidly with 0.32 equiv hydrogen evolution and anthraquinone is cleanly reduced to the 9,10-dihydoxyanthracene stage. Carboxylic acids liberate hydrogen rapidly and quantitatively, however further reduction does not occur. Anhydrides utilize 2 equiv of hydride and acyl chlorides are reduced to the corresponding alcohols rapidly. Lactones are reduced to the diol stage rapidly, whereas esters are reduced moderately (3-6 h). Terminal epoxides are rapidly reduced to the more substituted alcohols, but internal epoxides are reduced slowly. Primary and tertiary amides are inert to this reagent and nitriles are reduced very slowly. 1-Nitropropane evolves hydrogen rapidly without reduction and nitrobenzene is reduced to the azoxybenzene stage, whereas azobenzene and azoxybenzene are inert. Cyclohexanone oxime evolves hydrogen without reduction. Phenyl isocyanate utilizes 1 equiv of hydride to proceed to formanilide stage. Pyridine and quinoline are reduced slowly, however pyridine N-oxide takes up 1.5 equiv of hydride in 1 hr. Disulfides are rapidly reduced to the thiol stage, whereas sulfide, sulfoxide, sulfonic acid and sulfone are practically inert to this reagent. Primary alkyl bromide and iodide are reduced rapidly, but primary alkyl chloride, cyclohexyl bromide and cyclohexyl tosylate are reduced slowly.

• Nuclear Engineering and Technology
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• v.41 no.2
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• pp.179-186
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• 2009

This paper presents a thermal creep test under internal pressure and post-test characterization performed on high burnup (68 MWd/kgU) ZIRLO. This research has been done by the CSN, ENRESA, and ENUSA in order to investigate the behavior of advanced cladding materials in contemporary PWRs at higher burnup under dry cask storage conditions. Also, to investigate the hydride reorientation, the cool-down of the samples after the test has been done in a coordinated manner with the internal pressure. The creep results obtained are consistent with the expected behavior from reference CWSR material, Zr-4. During the test, the material retained significant ductility: one specimen leaked during the test at an engineering strain of the tube section of 17%; remarkably, the crack closed due to de-pressurization. Although significant hydride reorientation occurred during the cool-down under pressure, no specimen failed during the cool-down.

• Transactions of the Korean hydrogen and new energy society
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• v.2 no.1
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• pp.39-46
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• 1990

In order to improve the power of hydride heat pump, prototype heat pump was constructed using $Zr_{0.95}Ti_{0.05}Cr_{0.9}Fe_{1.1}$-$Zr_{0.9}Ti_{0.1}Cr_{0.6}Fe_{1.4}$ which had very good hydrogenation properties. The power changed with operating parameter such as cycle time, air flow rate, and temperature of hot air was investigated. The power shows maximum value with cycle time. The power increased with air flow rate and temperature of hot air. The power of the heat pump was $65-72 Kcal/Kg-alloy{\cdot}h$ under optimum operating condition, which was superior to that the system using $LaNi_{0.9}Al_{0.3}-MmNi_{4.15}Al_{0.66}Fe_{0.2}$ alloy pairs.

• Analytical Science and Technology
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• v.25 no.6
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• pp.339-344
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• 2012

In this research, hydride generation in HPLC-ICPMS for the selenium speciation was investigated. Chemical and photochemical vapor generation techniques were compared for the effective generation of selenium vapour. $HBr/KBrO_3$ was used for the chemical reduction and a UV lamp was used for the photochemical reduction. It was found out that the photochemical reduction was more effective than the chemical reduction in all of selenium species studied. The optimum conditions for the generation of vapour are 0.4% KI, 2.5% $NaBH_4$, and 1.0 M HCl. The enhancement factor using a photochemical hydride generation was from 6.3 to 16.7 times for inorganic and organic selenium species.