Graphite doesn't burn well, but it does erode away in a stream of hot oxygen or CO2. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660019918.pdf https

Graphite doesn't burn well, but it does erode away in a stream of hot oxygen or CO2. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19660019918.pdf https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/196600... The CO2-based Advanced Gas-cooled Reactor runs at 650C to keep core lifespan reasonable. https://en.wikipedia.org/wiki/Advanced_Gas-cooled_Reactor https://en.wikipedia.org/wiki/Advanced_Gas-cooled_Reactor