It is, but it's safer, since it's a fuel salt loop that has radioactive fuel mixed in, which is too dilute to melt down. It powers a second, independent molten salt loop that goes to a water boiler elsewhere in the system. This has a variety of benefits, and also depends on the tech. But one, it stops meltdowns. And two, if the salt loop or boilers fail, it doesn't release superheated, radioactive steam since the boiler is elsewhere in the complex.

Some can also recycle radioactive fuel that is already spent too.

Molten salt technology also has other benefits, nuclear energy aside. In solar towers with molten salt technology, it boils salts which then power a steam turbine. The salts are fucking hot, and stay hot enough to boil water for 12 hours after the sun has stopped shining. In the morning, some fuel is used to heat up the salts in prep for the sunlight. So, while it does use a bit of carbon, it provides reliable baseload energy that can serve the grid uninterrupted at night/during storms :)

Can't get the pic to link right. Here's a solar tower