Totally passive, totally unavoidable shutdown and cooling. ThorCon combines a strongly negative temperature coefficient with a massive margin between the operating temperature of 700C and the fuelsalt’s boiling temperature (1430C). As the reactor temperature rises, ThorCon’s power output drops. This is an intrinsic, immutable property of the reactor physics. In any casualty that raises the temperature of the salt much above operating level, ThorCon will shut itself down.
If the high temperature persists, the freeze valve will thaw and drain the fuel from the primary loop to the drain tank, where the silo cold-wall will passively handle the decay heat.
There is no need for any operator intervention. Not in 3 days, not in 300 days, not in 3000 days. Nor are there any valves that must be realigned by either system or operator control as in some so called passive systems. In fact there is nothing the operators can do to prevent the shutdown, drain, and cooling.