I searched in the forum but didn't find a thread on this, so excuse me if this has been discussed before.
I'm still in the middle of debating LFTRs on another forum and another strong proponent of them posted this;
Concerning graphite fire. I found that powdered graphite has an ignition temperature of 730.00 deg C. It is conceivable that this temperature could be reached in a LFTR accident (operating temperature is about 600 deg C). So the danger of fire must be considered.
As mentioned, the containment can be kept full of inert gas. As a backup, in the event that somehow the containment is breached during a failure, inert gas cylinders within the containment could be designed to open when the temperature reaches some point (via melting plugs allowing slow release of gas), to assure that the graphite is kept in an inert gaseous environment until it has cooled well below ignition temperature.
I think this is necessary for a LFTR, but it is also a passive system that cannot fail due to loss of power, some type of mechanical failure or human error.
So I was wondering what is the risk of the graphite core in an LFTR catching fire. It would be immersed in molten salt so wouldn't be exposed to oxygen I was thinking and also the constant high temperatures of the reactors should anneal the graphite releasing the build up Wigner energy?
Is there a risk of graphite fire above 730 C in an operating LFTR or one that has had it's fuel drained in an emergency?