New Molten Salt Thorium Reactor Powers Up for First Time in Decades

A team from the Nuclear Research and Consultancy Group (NRG) the Netherlands has built the first molten salt reactor powered by thorium in decades.

It's a work in progress because they have not worked out the best materials to deal with the very corrosive conditions inside the reactor, but it is running. I think that's what everybody in the field is working on right now. It's not a very useful reactor if you have to shut it down every year to replace the reaction chambers, pipes, and valves. The main problem is that hot lithium ions are very reactive, so they dissolve the uranium and thorium fuel, but they also combine with the reactor structure material, dissolving it into the molten salt. The other type of corrosion is actually nuclear: Transmutation changes elements in the reactor structures.
The problem is a bit easier because it not under pressure, like in other types of reactor.