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논문 기본 정보
- 자료유형
- 학술저널
- 저자정보
- 발행연도
- 2013.1
- 수록면
- 211 - 218 (8page)
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초록· 키워드
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Large quantities of irradiated graphite waste from graphite-moderated nuclear reactors exist and are expected to increase in the case of High Temperature Reactor (HTR) deployment [1,2]. This situation indicates the need for a graphite waste management strategy. Of greatest concern for long-term disposal of irradiated graphite is carbon-14 (14C), with a half-life of 5730 years. Fachinger et al. [2] have demonstrated that thermal treatment of irradiated graphite removes a significant fraction of the 14C, which tends to be concentrated on the graphite surface. During thermal treatment, graphite surface carbon atoms interact with naturally adsorbed oxygen complexes to create COx gases, i.e. “gasify” graphite. The effectiveness of this process is highly dependent on the availability of adsorbed oxygen compounds. The quantity and form of adsorbed oxygen complexes in pre- and post-irradiated graphite were studied using Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Xray Photoelectron Spectroscopy (XPS) in an effort to better understand the gasification process and to apply that understanding to process optimization. Adsorbed oxygen fragments were detected on both irradiated and unirradiated graphite; however,carbon-oxygen bonds were identified only on the irradiated material. This difference is likely due to a large number of carbon active sites associated with the higher lattice disorder resulting from irradiation. Results of XPS analysis also indicated the potential bonding structures of the oxygen fragments removed during surface impingement. Ester- and carboxyl- like structures were predominant among the identified oxygen-containing fragments. The indicated structures are consistent with those characterized by Fanning and Vannice [3] and later incorporated into an oxidation kinetics model by El-Genk and Tournier [4].
Based on the predicted desorption mechanisms of carbon oxides from the identified compounds, it is expected that a majority of the graphite should gasify as carbon monoxide (CO) rather than carbon dioxide (CO2). Therefore, to optimize the efficiency of thermal treatment the graphite should be heated to temperatures above the surface decomposition temperature increasing the evolution of CO [4].
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참고문헌 (17)
참고문헌 신청
A. MONTOYA / 2001 / CO Desorption from Oxygen Species on Carbonaceous Surfaces: 1. Effects of the Local Structure of the Active Site and the Surface Coverage / J. Phys. Chem
D. BRIGGS / 1983 / Practical Surface Analysis by Auger and X-ray Photoelectron Spectroscopy / John Wiley & Sons
ELECTRIC POWER RESEARCH INSTITUTE / 2006 / Graphite Decommissioning: Options for Graphite Treatment, Recycling, or Disposal, including a Discussion of Safety-Related Issues
G. MIESSEN / 2001 / Numerical Studies of the Heterogeneous Combustion of Char Using Detailed Chemistry / Chemosphere 42 : 609 ~ 613
H. WATANABE / 1993 / Local Etching Effect of Fine Gold Particles Deposited on Graphite / Jpn. J. Appl. Phys. 32 : 2809 ~ 2813
D. BRIGGS / 1983 / Practical Surface Analysis by Auger and X-ray Photoelectron Spectroscopy / John Wiley & Sons
ELECTRIC POWER RESEARCH INSTITUTE / 2006 / Graphite Decommissioning: Options for Graphite Treatment, Recycling, or Disposal, including a Discussion of Safety-Related Issues
G. MIESSEN / 2001 / Numerical Studies of the Heterogeneous Combustion of Char Using Detailed Chemistry / Chemosphere 42 : 609 ~ 613
H. WATANABE / 1993 / Local Etching Effect of Fine Gold Particles Deposited on Graphite / Jpn. J. Appl. Phys. 32 : 2809 ~ 2813
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