You are correct- I use the term meltdown to encapsulate an event that causes significant damage to the control of a reactor, such as an earthquake followed by a tsunami.
In such an event, an MSR has a "drain tank" that sits below the reactor. In an emergency, gravity drops the salt into the drain tank, and the nuclear reaction safely comes to a halt- all with zero human intervention.
Perhaps it would be better to use the term 'containment failure'.
I'm surrounded by vehement anti-nuclear types, you know the ones who get arrested for their environmental activism antics. When talking about nuclear technology with them I find it helpful not to utter certain words like 'meltdown', 'weapons', etc etc.
