石墨作为慢化材料和反射层材料，是维持高温气冷堆正常运行的重要组成部分。但是，核石墨在高温下容易被氧化性气体腐蚀，从而威胁反应堆安全。核石墨的腐蚀问题虽然被人们广泛关注，但是其腐蚀机理仍在研究的过程中。本文采用气体成分测试分析法研究了高温气冷堆用核石墨IG-110的氧气、水蒸汽气体腐蚀行为。我们成功设计并搭建了一套高温腐蚀石墨，并且可以在线检测出口气体成分的实验装置，通过实际测试分析验证了其检测的可靠性。通过改变腐蚀温度，发现氧气腐蚀石墨粉和石墨球时，600℃以下O2未能完全反应；600℃以上O2完全反应，且产物随温度升高依次为CO2、CO。水蒸汽腐蚀时，800℃以下不发生反应；1242℃时，绝大部分水蒸汽都参与了腐蚀反应，反应产物为H2和CO。无论是从反应发生的温度、还是从单位摩尔气体消耗的石墨的量来说，水蒸汽对堆内核石墨的腐蚀程度都远小于氧气。通过改变O2浓度，发现O2浓度对石墨粉和石墨球的氧气腐蚀机制没有明显的影响，出口各组分气体的浓度只是随着通入O2浓度的增加而线性增加。进一步研究石墨粉和石墨球的腐蚀行为表明，无论是氧气还是水蒸汽腐蚀，直径6mm的石墨球的腐蚀温度比石墨粉的腐蚀温度高大约50-100℃时，两者的腐蚀产物近似。这说明6mm石墨球要比石墨粉更耐腐蚀。而堆内实际使用的6cm石墨球的耐腐蚀性能应该会更好。

As the moderator, reflector and structural material in High Temperature Gas-cooled Reactor (HTGR), nuclear graphite is one of the key materials to maintain normal reactor operation. However, graphite can be easily oxidized by oxidizing gases under high temperature, which may threaten reactor safety. The issue of nuclear graphite corrosion has been discussed widely, but the mechanism of graphite corrosion still remains unclear. Here in our work, gas concentration measurement is applied to study the oxygen and vapor corrosion behavior of IG-110, a brand of nuclear graphite which will be applied in HTGR. A set of high temperature gas corrosion facility is set up, and gas chromatography is used to detect its outlet gas concentration data. Tests have been carried out to ensure the reliability of the whole set of facility.Both for graphite powder and balls corroded by oxygen, not all oxygen reacts with graphite below 600 °C; but above 600°C, oxygen all reacts, and the corrosion product changes from CO2 to CO as temperature goes up. For vapor corrosion, corrosion does not happen below 800°C, but becomes severe at 1242°C. Corrosion product is H2 and CO. The danger of vapor corrosion is much less than that of oxygen corrosion, because it happen at a higher temperature, and vapor consumes less graphite when same moles of vapor and oxygen reacts with graphite.The change in inlet oxygen concentration does not alter corrosion mechanism both for graphite powder and balls. The outlet concentration of each product gas just rises linearly as inlet oxygen concentration goes up.A thorough comparison between powder and ball corrosion shows that the Ø6mm graphite balls has better corrosion resistance than powder, because it has less product gas than powder under same temperature. It can be inferred that the actual ball used in HTGR, which is 6 cm in diameter, may have even better corrosion resistance.