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Jang, Changheui

Publications and source records attributed to Jang, Changheui.

Advancement of Supercritical Carbon Dioxide Technology through Round Robin Testing and Fundamental Modeling

Growing interest in supercritical carbon dioxide (sCO 2 ) cycles for advanced reactors is driving the need for corrosion data on candidate plant materials. The sCO 2 Brayton cycle is being considered for power conversion systems for a number of nuclear reactor concepts including the sodium fast reactor, fluoride salt-cooled high temperature reactor, high temperature gas reactor, and several types of small modular reactors. Multiple organizations have developed test facilities to address the corrosion data knowledge gap in high temperature, high pressure sCO 2 environments but, to date, there has been no formal test program among these organizations to validate the consistency of the data they produce. A demonstration of comparable and reproducible results enables a coordinated effort to explore the sCO 2 parameter space relevant to advanced reactor technology. This proposal establishes a round robin test plan for sCO 2 corrosion testing and the organization of a sCO 2 Materials Group to guide future materials testing directions. Furthermore, this proposal outlines efforts to elucidate the mechanisms of sCO 2 corrosion by performing identical tests in supercritical steam, testing model alloys with various composition and environmental conditions, accompanied by modeling efforts to study rate controlling mechanisms of corrosion and to help understanding the effects of impurities.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Characterization of Alloy 600 joints exposed to a high-temperature supercritical-carbon dioxide environment

Highlights: • Diffusion-bond showed similar corrosion and carburization behavior as parent matrix. • Diffusion-bond line migrated due to the Cr-depletion induced recrystallization. • Alloy 182 fusion-weld showed larger weight gains with outer Mn-rich oxides. • The presence of SiO{sub 2} in chromia suppressed carburization at the oxide/matrix interface. • Despite larger weight gains, Alloy 182 fusion-weld showed negligible tensile property changes. - Abstract: Two types of Alloy 600 joints, such as diffusion-bonded joint and Alloy 182 fusion-weld, were exposed to supercritical-CO{sub 2} environment at 550 and 650 °C (20 MPa) for 1000 h. The diffusion-bond region showed similar oxidation characteristics as parent Alloy 600, but the migration of diffusion bond line below oxide layer was observed due to the Cr-depletion induced recrystallization. For Alloy 182 fusion-weld, outer Mn-rich oxides (Mn{sub 3}O{sub 4} and MnCr{sub 2}O{sub 4}) and a small amount of inner SiO{sub 2} mixed with chromia were formed due to high Mn and Si contents. The presence of SiO{sub 2} in chromia suppressed carburization at the oxide/matrix interface, which resulted in the formation of an amorphous C layer between the outer Mn-rich oxide and inner Cr-rich oxide. For Alloy 182 fusion-weld, tensile property changes after exposure to supercritical-CO{sub 2} environment were negligible.

36 MATERIALS SCIENCE↗