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  • Author or Editor: Chang Lee x
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Abstract  

Radioactivation of Zircaloy-4 (Zry-4) and Zirlo cladding hulls after 55 GWD/tU burn-up and 10 years of cooling was simulated using the ORIGEN-S code. The simulation results revealed that 125Sb and 60Co are major contributors of both radioactivity and decay heat in the case of the Zry-4 hulls. For the Zirlo hulls, 93mNb and 125Sb consisted 82.2% of radioactivity while 125Sb and 60Co emitted 77.9% of decay heat. Although the radioactivity between the Zry-4 (1.17 Ci for 1 kg of fresh Zry-4) and Zirlo (1.38 Ci for 1 kg of fresh Zirlo) hulls was not significantly different, decay heat of the activated Zry-4 hulls (8.58 mW) was much larger than 1.62 mW of the activated Zirlo hulls. This gap might have come from the different major constituents of Zry-4 (Zr, Sn, Fe, and Cr) and Zirlo (Zr, Sn, Nb, and Fe) resulting in different radioactive nuclides after radioactivation. Chlorination reaction behavior of the activated Zry-4 and Zirlo hulls was performed using the HSC chemistry code. Constituents of recovered ZrCl4 were investigated via changes of Gibbs free energy and boiling points of resulting chlorides. The calculation results suggested that radioactivity and decay heat might decrease by 49.0 and 81.8%, respectively, in the ZrCl4 recovered from the activated Zry-4 hulls. In the case of Zirlo, it was expected that radioactivity and decay heat might decrease by 11.6 and 13.0%, respectively, after the chlorination reaction. Effect of cooling time on radioactivity and decay heat was also investigated.

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This paper investigates the attitudes of political parties to international trade in 23 OECD countries in the period 1972–2004. Employing different datasets and various measures of trade openness, we examine how government ideology affects trade policy preferences and whether this relationship depends on international and domestic factors by employing the panel data techniques. Our main findings are that an increase in the leftist orientation of the government leads to more restrictive or less open trade policies, while right-oriented parties are likely to express more favor to trade openness. Secondly, international factors such as globalization in political and social dimension as well as financial openness, have a strong positive influence on a given party’s trade policy preferences. Thirdly, we offer clear evidence that a political party will change its partisan positions due to the influence of the domestic economic and institutional environment.

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Abstract  

For the determination of 210Po in water samples, two alternative procedures (a) DDTC solvent extraction and (b) extraction chromatography using Sr Resin were selected and then validated in terms of trueness, repeatability and reproducibility with a tap water spiked with a known amount of 210Po. In this work the optimization conditions for the auto-deposition of Po for source preparation were also studied.

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Abstract  

Facing such serious problems in cultivating IT engineers as a mismatch in supply and demand of IT workers, shortage of globally competitive IT professionals, and insufficient education and training of university graduates, the Korean government has decided to adopt a new paradigm in national IT engineering education, based on supply chain management (SCM) in manufacturing. SCM weights improving competitiveness of the supply chain as a whole via a long-term commitment to supply chain relationships and a cooperative, integrated approach to business processes. These characteristics of SCM are believed to provide insight into a more effective IT education and industry-university relationship. On the basis of the SCM literature, a model for industry-oriented IT higher education is designed, and then applied in the field of computer-software engineering in Korea.

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Abstract  

The seasonal variation of the 7Be activities in air and the size distribution of the 7Be aerosols were studied by using a continuous air sampler and a five stage cascade impactor. The mean monthly activity level of 7Be at the Korea Atomic Energy Research Institute (KAERI) site varied from 0.5 to 4.8 Bq·m−3 and revealed a seasonal variation, in which the 7Be activity levels were high in winter and low in summer. The mass size distribution showed a bi-modal distribution with a higher peak around 0.49 μm and a smaller peak between 3 μm and 7.2 μm. The activity median aerodynamic diameter (AMAD) decreased with increasing ambient 7Be concentrations. The mean residence times by using a mean growth rate of 0.004 μm·h−1 were estimated to be 2.5–6.4 days. The AMAD has an increasing tendency with higher relative humidity. It seemed that the high humidity condition facilitated the growth of the aerosol, resulting in increased deposition rates of the aerosols and the low 7Be content in the surface air. The AMAD of the 7Be aerosols increased with an increasing temperature, but the temperature dependency of AMAD should be explained with geological and meteorological conditions.

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Abstract  

To meet the requirements of NUREG-0737 and Atomic Energy Council, Republic of China, the post accident sampling systems have recently been established at Taiwan power stations. The lead shielded cask for transportation of grab liquid sample from sampling station to the off-site backup laboratory was designed, based on the functions of sample taken vertically from sample station and the horizontal transferring of sample vial to the cell of backup laboratory. Spectrophotometric, titrimetric and ion chromatographic methods were studied and comparisons made for the analyses of boron and chloride. It can be concluded that suppressed ion chromatography with remote handling in a lead cell is best for determining boron and chloride simultaneously in a high radioactive sample solution. The method with high accuracy, less interference and rapid analysis is considered and discussed.

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Summary  

Some stability and convergence theorems of the modified Ishikawa iterative sequences with errors for asymptotically nonexpansive mapping in the intermediate sense and asymptotically pseudo contractive and uniformly Lipschitzian mappings in Banach spaces are obtained.

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Abstract  

Chlorination reaction behavior of Zircaloy-4 (Zry-4) was simulated by using the HSC code for three different chlorinating reagents of Cl2, HCl, and CCl4. Four major components (Zr, Sn, Fe, and Cr) of Zry-4 and their oxides which were produced during an oxidative decladding process were considered for the theoretical calculation. The simulation results revealed that Cl2 might convert metallic Zr, Sn, Fe, and Cr into their chloride forms, while oxides might not react with Cl2 at 380 °C. When HCl was employed as the chlorinating reagent, it was suggested that metallic Zr, Sn, and Cr might react with HCl while Fe and oxides might not. In the case of CCl4, it was shown that CCl4 could react with all of the metallic and oxide components to produce most amount of ZrCl4 when compared with Cl2 and HCl cases. Reaction behavior of the chlorinating reagents with residual spent nuclear fuel constituents (U3O8, MoO3, Pd, BaO, Y2O3, SrO, Rh2O3, RhO2, La2O3, CeO2, and Nd2O3) was also performed, and it was revealed that Cl2 and HCl might produce (PdCl2, BaCl2, SrCl2, RhCl3, LaCl3, and NdCl3) and (BaCl2, YCl3, SrCl2, RhCl3, LaCl3, and NdCl3), respectively. Although these by-products are produced, it was suggested that highly pure ZrCl4(g) which contains FeCl3(g) and SnCl4(g) as impurities might be recovered when Cl2 or HCl is employed as a chlorinating reagent because other by-products have higher boiling point than the reaction temperature of this study (380 °C). On the other hand, the theoretical calculation results showed that CCl4 might react with all the residual spent fuel constituents to produce additional gaseous impurities of UCl6 and MoCl5 to reduce the purity of ZrCl4 product.

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Abstract  

A sequential separation procedure has been developed for the determination of 99Tc, 94Nb, 55Fe, 90Sr and 59/63Ni in various radioactive wastes generated from nuclear power plants. Ion exchange and extraction chromatography were adopted for individual separation of the radionuclides. Precipitation was supplementarily utilized for both purification of the individual radionuclides and preparation of the radionuclide sources for use in a radioactivity measurement. The chromatographic separation behavior of the radionuclides both from the sample matrix metals and from one another was investigated using stable metals, Re (as a surrogate of 99Tc), Nb, Fe, Sr and Ni. The validity of the procedure for reliability and applicability was evaluated by measuring the recovery of the metal carriers added to synthetic radioactive waste solutions. The recoveries by the chromatographic separation were in the range of 84.8 to 102.2% with 2s of less than 8.6%, the recoveries by the precipitation being in the range of 84.3 to 97.3% with 2s of less than 10.9%.

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Abstract  

The thermochemical decomposition of agricultural by-product corn cob impregnated with ZnCl2, as a precursor material for producing the activated carbons, was investigated by thermogravimetric (TG) analysis at the heating rate of 5 and 10°C min–1 under a controlled atmosphere of nitrogen (60 ml min–1). The appearance of a peak in the differential thermogravimetric plot (DTG) in the temperature range of 400–600°C is significantly related to the extent of impregnation. The DTG curve of the sample impregnated with the optimal impregnation ratio of 175% (i.e., the ratio of ZnCl2 mass of 87.5 g in the 200 cm3 of water to corn cobmass of 50 g), which yields an optimal BET surface area of the activated carbon and displays a DTG peak at about 500°C. This may be partially due to the intense chemical activation and results in the formation of a porous structure in the activated solid residue. This observation is also in close agreement with previous results at optimal pyrolysis temperatures of 500°C and with similar experimental conditions. In order to support the results in the TG-DTG analysis, the development of pore structure of the resulting activated carbons thus obtained by previous studies was also examined and explained using the scanning electron microscopy (SEM).

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