Search Results

You are looking at 1 - 10 of 10 items for

  • Author or Editor: J. Kwon x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

The specific energy density from radioactive decay is five to six orders of magnitude greater than the specific energy density in conventional chemical battery and fuel cell technologies. We are currently investigating the use of liquid semiconductor based betavoltaics as a way to directly convert the energy of radioactive decay into electrical power and potentially avoid the radiation damage that occurs in solid state semiconductor devices due to non-ionizing energy loss. Sulfur-35 was selected as the isotope for the liquid semiconductor demonstrations because it can be produced in high specific activity and is chemically compatible with known liquid semiconductor media.

Restricted access

Abstract  

It is important to increase a throughput of the salt removal process from uranium deposits which is generated on the solid cathode of electro-refiner in pyroprocess. In this study, it was proposed to increase the throughput of the salt removal process by the separation of the liquid salt prior to the distillation of the LiCl–KCl eutectic salt from the uranium deposits. The feasibility of liquid salt separation was examined by salt separation experiments on a stainless steel sieve. It was found that the amount of salt to be distilled could be reduced by the liquid salt separation prior to the salt distillation. The residual salt remained in the deposits after the liquid salt separation was successfully removed further by the vacuum distillation. It was concluded that the combination of a liquid salt separation and a vacuum distillation is an effective route for the achievement of a high throughput performance in the salt separation process.

Restricted access

Abstract  

The distillation behaviour of cadmium at a reduced pressure was investigated to develop an actinide recovery process from a liquid cadmium cathode in a laboratory scale cadmium distiller. The apparent evaporation rate of cadmium increased with an increasing temperature whereas the rate decreased with an increasing vacuum pressure. The evaporation rate of cadmium varied within 9.7–40 g/cm2/h in the temperature range of 500–650 °C and pressure range of 0.5–10 Torr (0.0667–1.33 kPa). The theoretical values calculated by the Hertz–Langmuir relation were much higher than experimentally measured values. The deviation was compensated by an evaporation coefficient (α) obtained empirically. About 0.02–0.20 wt% of residue was left in the crucible after distillation and found to be CdO. It could be concluded that the temperature range of 500–650 °C is favourable for the cadmium distillation process if residual eutectic salt does not exist in the cadmium alloy surface.

Restricted access

Abstract  

A (D3C)2O (d6-acetone) target was irradiated with semi-monoenergetic neutrons generated from 9Be(p,n)9B reaction with 20 MeV protons to convert 13C and oxygen nuclides in the target into 14C. With both liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS) we measured the (D3C)2O (d6-acetone) liquid targets, which were combustible and easy to afford CO2 for the AMS measurements. The 14C yield measured by the LSC method turned out to be 80 times larger than that by the AMS method. This large discrepancy may be attributed to the loss of 14C atoms during the sample pretreatment in the AMS method such as combustion and cryogenic trapping of CO2. It means that 14C newly produced by nuclear reactions can exist in various chemical forms, i.e., C3D6O, CO, CO2, hydrocarbons, etc., and a simple sample pretreatment right after production can cause serious isotopic fractionation. Therefore, using the AMS method, extreme caution in sample pretreatment should be exercised when the 14C yield produced immediately by nuclear reaction is measured.

Restricted access

Abstract  

A study of the elution chromatographic separation of lithium isotopes was carried out with NTOE-bonded Merrifield peptide resin. This resin had a capacity of 0.29 meq/g dry resin. Upon column chromatography [0.2 cm(I.D)×32 cm (height)] using 1.0M NH4Cl solution as an eluent, a single separation factor of 1.026 was obtained by the Glueckauf theory. The heavier isotope, 7Li was concentrated in the resin phase, while the lighter isotope, 6Li was enriched in the solution phase.

Restricted access

Abstract  

We have measured the cross sections of the 16O(n,t) reactions above 18.1 up to 33.1 MeV in an neutron activation method. H2O (water) as an 16O target was irradiated with semi-monoenergetic neutrons generated from the 9Be(p,n)9B reaction with 25–35 MeV protons. The neutron flux was obtained with the aid of previous study by Uwamino et al. (Nucl Instr Methods A 271:546, 1988). The tritium activities were measured by using the liquid scintillation counting (LSC) method. The present value for the cross section of 16O(n,t) reaction agrees with previous values measured by using the same LSC method at similar neutron energy ranging from 18.1 up to 33.1 MeV.

Restricted access

Summary

A simple high-performance anion-exchange chromatography-integrated pulsed amperometric detection method was developed to determine the gammaaminobutyric acid (GABA) content in mulberry. GABA was separated in anion-exchange column under isocratic condition of 20 mM sodium hydroxide solution and detected at integrated pulsed amperometric detection at pico-gram levels. The contents of GABA in the leaf, stem, and root bark of mulberry were calculated without any derivatization or sample purification process using this method. This method showed good linearity, precision, and accuracy for GABA analysis.

Full access

This study was aimed at evaluating the efficacy of different mineral separation procedures to validate the EN1788 (2001) European Union standard protocol for better identification of irradiated fish and shellfish. The silicate minerals were isolated with physical density separation method from two types of non-irradiated freeze-dried fish and shellfish that included Pacific saury (Cololabis saira), mackerel (Scomber japonicus), shrimp (Penaeidae metapenaeus), and mussel (Mytilus coruscus). Radiation-specific thermoluminescence (TL) peaks (glow curve 1) were observed between 150–250 °C. The peaks are typical for the irradiated food; despite the samples being not irradiated. Apparently it showed that the isolated minerals were contaminated with organic materials such as bone, etc. Acid-hydrolysis digestion was employed to remove the possible contaminants. The minerals obtained through alternative pre-treatment showed no TL curves in radiation specific temperature range. Moreover, acid hydrolysis extraction resulted in producing higher mineral yields and lower background luminescence. Results were also confirmed by calculating TL ratios (glow curve 1/glow curve 2) to confirm the irradiation history of samples. Furthermore, different time and temperature treatments on TL intensity of irradiated standard quartz (SiO2) minerals showed that the acid-hydrolysis can be adjusted to 50 °C and 3 h for better luminescence determinations.

Restricted access
Journal of Radioanalytical and Nuclear Chemistry
Authors: K. Kim, J. Bae, B. Park, D. Ahn, S. Paek, S. Kwon, J. Shim, S. Kim, H. Lee, E. Kim, and I. Hwang

Abstract  

A pyrochemical processing has become one of the potential technologies for a future nuclear fuel cycle. An integrated multi-physics simulation and electrotransport model of a molten-salt electrolytic process are proposed and discussed with respect to the recovery of pure uranium when using thermochemical data. This study has been performed to provide information for diffusion boundary layers between the molten salt (KCl-LiCl) and electrode. The diffusion-controlled electrochemical model demonstrate a prediction of the electrotransport behaviors of LWR spent fuel as a function of the time up to the corresponding electrotransport satisfying a given applied current based on a galvanostatic electrolysis.

Restricted access