A Study of the Oxidation Behaviour of Pile Grade A (PGA) Nuclear Graphite Using Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and X-Ray Tomography (XRT).
A Study of the Oxidation Behaviour of Pile Grade A (PGA) Nuclear Graphite Using Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and X-Ray Tomography (XRT).
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DOI：
10.1371/journal.pone.0143041
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Scott TB
中科院分区：
文献类型：
--
作者：
Payne L;Heard PJ;Scott TB
堆A级(PGA)石墨被用作英国第一代Magnox核电反应堆的慢化和反射中子的材料。由于除一个反应堆外，所有这些反应堆现在都已关闭，因此有必要在堆芯退役之前了解材料的残留状态，特别是14C等关键放射性污染物的位置和浓度。用热重分析、扫描电子显微镜和X射线层析技术研究了未辐照的PGA石墨在600-1050°C温度范围内在空气和氮气中的氧化行为，以探讨利用热降解技术检测辐照材料中14C分布的可能性。观察到PGA石墨的热分解遵循以前工作人员历史上确定的三种氧化模式，即在低于600°C的温度下进行有限的均匀氧化，在较高温度下进行大量的外部氧化。这项工作表明，PGA石墨的不同氧化机制可以发展成一种方法学，用来表征经辐照处理的石墨中14C的分布和浓度。
Pile grade A (PGA) graphite was used as a material for moderating and reflecting neutrons in the UK’s first generation Magnox nuclear power reactors. As all but one of these reactors are now shut down there is a need to understand the residual state of the material prior to decommissioning of the cores, in particular the location and concentration of key radio-contaminants such as 14C. The oxidation behaviour of unirradiated PGA graphite was studied, in the temperature range 600–1050°C, in air and nitrogen using thermogravimetric analysis, scanning electron microscopy and X-ray tomography to investigate the possibility of using thermal degradation techniques to examine 14C distribution within irradiated material. The thermal decomposition of PGA graphite was observed to follow the three oxidation regimes historically identified by previous workers with limited, uniform oxidation at temperatures below 600°C and substantial, external oxidation at higher temperatures. This work demonstrates that the different oxidation regimes of PGA graphite could be developed into a methodology to characterise the distribution and concentration of 14C in irradiated graphite by thermal treatment.