A novel method for quantifying irradiation damage in nuclear graphite using Raman spectroscopy
A novel method for quantifying irradiation damage in nuclear graphite using Raman spectroscopy
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DOI：
10.1016/j.carbon.2023.118181
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发表时间：
2023-09
期刊：
影响因子：
10.9
通讯作者：
Ming Jiang;K. Ammigan;George Lolov;Frederique Pellemoine;Dong Liu
中科院分区：
文献类型：
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作者：
Ming Jiang;K. Ammigan;George Lolov;Frederique Pellemoine;Dong Liu
长期以来，拉曼光谱一直被用来研究碳/石墨材料的辐照损伤。然而，目前还不清楚不同类型材料的测量结果是否直接具有可比性。此外，在具有辐照损伤梯度的核石墨中，分离辐照温度和辐照剂量对总损伤的贡献目前还不太可行，因为它需要在相应的温度和辐照剂量范围内进行一套完整的试验堆辐照实验。因此，提出并发展了一种新的方法来量化晶体水平上的总辐射损伤演化，该方法基于石墨拉曼G带位置移动。具体地说，从具有质子辐照损伤梯度的微细颗粒POCO ZXF-5Q石墨的断口收集到的大量光谱，利用公开的文献拉曼数据绘制了HOPG、BEPO(AXGP石墨)、PCEA和IG-110石墨的G带位置随dpa的变化关系。该POCO石墨在2σ束流半径范围内的总损伤能级在∼350-370℃时相当于∼2-5 dpa。由此导出的G带位置被映射到三阶段非晶化轨迹模型，表明束流中心区已进入第二阶段，即从纳米晶石墨向非晶碳的转变。G带位置相对移位(ΔG)曲线的“回转”峰值作为总损伤的函数，可用于在役寿命预测。开发的方法有可能统一不同级别的核石墨在不同温度下受到离子、中子和质子辐射造成的总损害水平。
Raman spectroscopy has long been used in studying irradiation damage in carbon/graphite materials. It is however unclear if the measurements from different types of materials are directly comparable. Further, decoupling the contribution from irradiation temperature and fluence to the total damage in nuclear graphite possessing irradiation damage gradient is currently not readily feasible as it requires a complete set of test reactor irradiation experiments over the relevant temperature and fluence range. A novel methodology has therefore been proposed and developed to quantify total irradiation damage evolution at crystal level based on graphite Raman G-band position shift. Specifically, G-band positions derived from a large number of spectra collected from the fractured surface of microfine-grained POCO ZXF-5Q graphite possessing proton irradiation damage gradient were plotted with open literature Raman data on HOPG, BEPO (AXGP graphite), PCEA and IG-110 graphite as a function of dpa. The total damage level within 2σ beam radius in this POCO graphite was estimated to be equivalent to ∼2–5 dpa at ∼350–370 °C. Derived G-band positions were then mapped to the three-stage amorphization trajectory model indicating beam centre area has entered the second stage, i.e., transitioning from nanocrystalline graphite into amorphous carbon. G-band position relative shift (ΔG) curve with a ‘turn-around’ peak as a function of total damage can be used for in-service lifetime prediction. The developed methodology has the potential to ‘unify’ total damage levels across different grades of nuclear graphite caused by ion, neutron and proton irradiation at different temperatures.