What if there is a meltdown?
You can’t have a meltdown in a molten salt reactor, the core is already molten. In a standard reactor, a meltdown is a potential disaster. In a fluid fueled reactor, its normal operating procedure.
What if there’s a leak?
All the salt is solid at room temperature. if any salt leaks out, it will solidify.
What if there’s an explosion?
There is no internal pressure in the LFTR. In fact, there is a slight negitive pressure. If anything were to break open in the reactor, the salt would simply solidify.
What if the reactor overheats?
If the fuel salt overheats, the salt expands, which makes the reaction slow down and eventually stop. If the temperature of the salt rises too high, a solid plug of salt in a drain pipe would melt and the fuel would drain to a dump tank where a nuclear reaction is not possible. This ‘freeze plug’ can also be used to simply switch the reactor off.
What about proliferation?
A LFTR is a very poor option for making nuclear weapons. No weapon has ever been made from U233 (Uranium 233), the LFTR’s main fuel. In fact, it could burn up old weapons material along with waste from solid fuel reactors.