Characterization of 14C in neutron irradiated NBG-25 nuclear graphite
Characterization of 14C in neutron irradiated NBG-25 nuclear graphite
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DOI：
10.1016/j.jnucmat.2014.01.041
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发表时间：
2014-05-01
影响因子：
3.1
通讯作者：
Dunzik-Gougar, Mary Lou
中科院分区：
文献类型：
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作者：
LaBrier, Daniel;Dunzik-Gougar, Mary Lou
最近的研究表明，经反应器辐照的石墨中存在最高浓度的 C-14 污染物，存在于表面和近表面层内。采用表面敏感分析技术（XPS、ToF-SIMS、SEM/EDS 和拉曼）来确定辐照 NBG-25（核级）石墨表面上 C-14 的化学性质。在经过辐照的 NBG-25 表面上发现了几种 C-14 前体物质；这些物质的数量在地下深度减少，这进一步表明 C-14 的形成主要是一种表面集中现象。受辐照的 NBG-25 表面上几种表面氧化物复合物的增加直接归因于中子辐照。在辐照的 NBG-25 表面上发现了更多数量的氧化物键（与未辐照的样品相比），其形式为晶格间键（例如醚）和悬空键（例如羧酸酯和酮）；这些键类型的数量也随着地下深度的增加而减少。 (C) 2014 Elsevier B.V. 保留所有权利。
Recent studies suggest that the highest concentration of C-14 contamination present in reactor-irradiated graphite exists on the surfaces and within near-surface layers. Surface-sensitive analysis techniques (XPS, ToF-SIMS, SEM/EDS and Raman) were employed to determine the chemical nature of C-14 on irradiated NBG-25 (nuclear grade) graphite surfaces. Several C-14 precursor species are identified on the surfaces of irradiated NBG-25; the quantities of these species decrease at sub-surface depths, which further suggests that C-14 formation is predominantly a surface-concentrated phenomenon. The elevated presence of several surface oxide complexes on irradiated NBG-25 surfaces are attributed directly to neutron irradiation. Larger numbers of oxide bonds were found on irradiated NBG-25 surfaces (when compared to unirradiated samples) in the form of interlattice (e.g. ether) and dangling (e.g. carboxylate and ketone) bonds; the quantities of these bond types also decrease with increasing sub-surface depths. (C) 2014 Elsevier B.V. All rights reserved.