Comparative analysis of microstructure and reactive sites for nuclear graphite IG-110 and graphite matrix A3

JOURNAL OF NUCLEAR MATERIALS

卷:528

Article

Wu, Huali²  Gakhar, Ruchi³  Chen, Allen²  Lam, Stephen⁵  Marshall, Craig P.⁴  Scarlat, Raluca O.¹ 

[1] Univ Calif Berkeley, Dept Nucl Engn, Berkeley, CA 94720 USA

[2] Univ Wisconsin, Dept Engn Phys, Madison, WI 53706 USA

[3] Idaho Natl Lab, 2525 Fremont Ave, Idaho Falls, ID USA

[4] Univ Kansas, Dept Geol, Lawrence, KS 66045 USA

[5] MIT, Dept Nucl Sci & Engn, 77 Massachusetts Ave, Cambridge, MA 02139 USA

关键词: Tritium;    Hydrogen;    Reactive carbon sites;    Graphite fluorination;    FHR;    MSR;    HTGR;   

DOI  :  10.1016/j.jnucmat.2019.151802

来源: Elsevier

【 摘 要 】

Nuclear graphite and graphite matrix are both high-purity, fine-grain, graphitized materials designed for use in Fluoride-Salt Cooled High Temperature Reactors (FHRs), High Temperature Gas Cooled Reactors (HTGRs), and Molten Salt Reactors (MSRs). Their ability to chemisorb radioisotopes (such as tritium) and their chemical stability is dependent upon the density of reactive carbon sites (RCS), which varies among grades of graphite and changes with neutron irradiation. While nuclear graphites have been extensively characterized, much less data is available for graphite matrix. The current study performs a comparative analysis of IG-110 nuclear graphite and A3 graphite matrix, by X-ray Diffraction (XRD), Raman, and H-2 uptake at 700 degrees C with H-2 partial pressure range of 300 Pa and 22 kPa. At 10 kPa, the RCS occupied by H-2 uptake per number of carbon atoms at the edge of a crystallite, H/C-edge, is 600(300) appm for IG-110 and 2300(200) appm for A3. Prior empirical studies for nuclear graphite establish a linear relationship between H/C and C-edge/C and degree of graphitization. The present study shows that these correlations no longer hold when extrapolating to graphite matrix; the type of defects and the defect density at the crystallite surface are different between IG-110 and A3 due to differences in raw materials and manufacturing method. (C) 2019 Elsevier B.V. All rights reserved.

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