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583 results on '"Eun, Hee-Chul"'

41. A study on solidification of CaCO3 powder containing C-14 by using a low melting glass material.

Author

Eun, Hee-Chul, Yang, Hee-Chul, Kim, Hyung-Ju, Kim, Sung-Jun, Jeon, Min-Ku, Lee, Keun-Young, and Seo, Bum-Kyoung

Subjects
*SOLIDIFICATION, *BISMUTH trioxide, *MELTING points, *ACTIVATED carbon, *COMPRESSIVE strength, *POWDERS
Abstract

CaCO3 powder containing C-14, which has a long half-life, is generated from the treatment process of spent activated carbons from the air cleaning system in a nuclear facility, can be decomposed into CaO and CO2 gas at a temperature above 600 °C. This CaCO3 must be fabricated into a stable waste form for final disposal at a temperature below 600 °C. In this study, tests on the solidification of CaCO3 into a waste form were conducted using a bismuth oxide glass with a low melting point. The CaCO3 was solidified into a homogeneous glass–ceramic waste form with a waste loading of 40 wt% at 460 °C without CaCO3 decomposition. This waste form had high values of density (3.15 g/cm3) and compressive strength (42.09 MPa), and it was confirmed through leaching tests (ANS 16.1, PCT) that the waste form also had a high chemical durability. [ABSTRACT FROM AUTHOR]

Published
2022
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42. Chlorination behavior of Li(Ni1/3Co1/3Mn1/3)O2.

Author

Jeon, Min Ku, Kim, Sung-Wook, Oh, Maengkyo, Eun, Hee-Chul, and Lee, Keunkyoung

Abstract

The chlorination behavior of Li(Ni1/3Co1/3Mn1/3)O2 (NCM) was investigated as a function of the reaction temperature (400–600 °C) and time (1–8 h) for application in a chlorination-based recycling process. Structural analysis results revealed that chlorination leads to a sequential transition from a hexagonal LiMO2 structure to a hexagonal Li1−x′MO2−y′ (observed only at 400 °C), a hexagonal Li1−xMO2−y (x≥x′, y≥y′, at 400–600 °C), and a spinel-type M3O4 phase (≥500 °C, M represents Ni,Co,Mn). It was also found that this structural transition is accelerated by an increase in the reaction temperature, except at 600 °C, where the thermal decomposition of the Li1−xMO2−y phase inhibited the formation of the M3O4 phase. Weight changes of the samples suggested that the chlorination of the transition metals begins at 500 °C and that its rate increases with an increase in the reaction temperature. It was revealed by a composition analysis that an increase in the reaction temperature (except at 600 °C) and longer times result in a higher Li removal ratio. A temperature of 550 °C was proposed as the optimum temperature for the chlorination of NCM in consideration of the findings from this work. [ABSTRACT FROM AUTHOR]

Published
2022
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