Pebble bed reactor?
I'm not sure...
It looks like Pebble Bed still has some R&D interest in SA and China...
US support for PBMR intensifies Areva, Westinghouse contest
but I don't think it's ready for prime time yet.
No... it was the old Shippingport Plant (Pressurized Water Reactor) outside of Pittsburgh that had been in operation since 1957. In the mid 70s they shut it down, removed to old core, and loaded a new U 233 core designed at the Westinghouse Bettis Labs. It was an experiment driven by the DoE and Adm. Rickover at the Div. of Naval Reactors.
The experiment ran for 5 years after which the thorium core was removed, taken to Idaho for study, and the Shippingport plant permanently decommissioned.