Re: "Moltex Energy..keep the fuel salt in fairly standard tubes which are replaced every 5 years,"
"That's not what cuts out the corrosion in their design.
The reactor parts are galvanized so the galvanizing is preferentially attacked, rather than the metallic structural components like the fuel rods or the core."
So I see the fuel tubes are to keep the radioactive salt separate from the coolant salt, simplifying things if the tank/pool of coolant salt leaks. I saw a comment on a youtube video purporting to be from Ian Scott (it could be a troll) saying that if the fuel salt on a standard MSR leaked it would be a nightmare:
"Your pre-edit question seemed to add "or small leaks" to the question. That is an important point. Dump tanks would have to be designed with large passive heat removal capacity - challenging but not impossible. Small leaks are a different challenge, and in many ways worse. The sustained ~kW/litre decay heat will raise the temperature of even a small leak to very high levels. I calculated that a 1mm layer on thick concrete would reach molten salt boiling point within hours. On a steel surface it will happen quicker since there is less heat capacity than a meter of concrete. In fact, I expect that some major heat producing fission products, especially cesium, would evaporate before that point and then deposit on every surface around. That would spread the heat load but create a monstrous decontamination problem.
Answering the nuclear regulators question of what happens when a pumped system springs a leak is going to be one of the hardest challenges to be faced. I am not sure that saying the unit would be shut down and replaced will be acceptable, the damaged unit would have to be demonstrated to be a safe waste disposal form and that is very difficult when major isotopes are in a water soluble form."
Do you have any thoughts on this John? I asked Kirk Sorenson on the energyfromthorium facebook page and got a very angry response (I think he has run out of patience due to all the Greenpeace trolls).