|FUD?
"Oak Ridge National Laboratory found during the Molten Salt Reactor Experiment, fluoride salts are incredibly corrosive and required hardened materials to safely contain them."
After 9000 full power hours there was NO discernable corrosion of the hastalloy-N pipework or deterioration of the graphite core
A couple of theoretical issues (mainly revolving around Tellurium) were identified in the 1970s and the formulation tweaked