High-temperature gas-cooled reactors (HTGRs) in operation use tristructural isotropic (TRISO) particles embedded in graphite and carbonized resin matrix to form the fuel element. This graphite matrix material serves as a supportive structural element, heat transfer medium, and neutron moderator. In HTGR designs, fuel compacts are exposed to helium coolant, which facilitates high outlet temperatures (750°C<T<950°C) and subsequently greater thermal efficiency than current commercial power reactors. However, data pertaining to the oxidation resistance of graphite matrix material in HTGR accident or off-normal conditions (<50k kPa pH₂O, 800°C<T<1600°C) is limited. In this study, both the oxidation behavior of matrix graphite material and its gas-phase products, including CO, CO₂, and H₂, are quantified in varied oxidant atmospheres using a coupled thermogravimetric analyzer and mass spectrometer. Oxidation rates reported here for varied steam (H₂O [g]) atmospheres are predominantly linear and comparable with literature values in the range of tested temperatures (800–1200°C). Changes in dominant matrix oxidation products from primarily CO to a mixture of CO, CO₂, and H₂ were observed at higher temperatures (≥1000°C) and steam atmospheres (≥5 kPa pH₂O). Kinetic data indicates that there was no shift in oxidation regime with chemical oxidation occurring at all temperatures and H₂O (g) atmospheres tested. These data provide insight into the oxidation behavior of graphite matrix material and will inform future testing conditions, notably mixed atmospheric conditions, of HTGR fuel elements.

运行中的高温气冷堆 (HTGR) 使用嵌入石墨和碳化树脂基质中的三结构各向同性 (TRISO) 颗粒来形成燃料元件。这种石墨基体材料用作支撑结构元件、传热介质和中子减速剂。在 HTGR 设计中，燃料压块暴露在氦冷却剂中，这有助于提高出口温度 (750°C<T<950°C)，随后比当前的商业动力反应堆具有更高的热效率。然而，有关石墨基体材料在高温气冷堆事故或非正常条件下（<50k kPa p H ₂ O，800°C<T<1600°C）的抗氧化性的数据是有限的。在本研究中，基体石墨材料及其气相产物（包括 CO、CO）的氧化行为₂，和H ₂，在使用耦合热重分析仪和质谱仪多样氧化剂大气压进行定量。此处报告的不同蒸汽 (H ₂ O [g]) 气氛的氧化率主要是线性的，并且在测试温度范围内 (800–1200°C) 与文献值相当。在较高温度 (≥1000°C) 和蒸汽气氛 (≥5 kPa p H ₂ O)下观察到主要基质氧化产物从主要为 CO 到 CO、CO ₂和 H ₂的混合物的变化。动力学数据表明，在所有温度和 H ₂下发生化学氧化时，氧化状态没有发生变化O (g) 大气测试。这些数据提供了对石墨基体材料氧化行为的深入了解，并将为 HTGR 燃料元件的未来测试条件，特别是混合大气条件提供信息。