Thorium (Th-232) isn't fissile, it needs to be bred up into U-233 to produce energy. U-233 works quite well in a nuclear weapon core (the US fired off at least two test devices back in the day). The U-233 in a proposed thorium reactor is pure, it has no contaminants that make it difficult to weaponise by an unscrupupous operator.
There are very few commercial breeder reactors still around or in operation since mined uranium is cheap and plentiful and breeders generally have a poor operational record, something that does not bode well for any thorium reactor that might be built since they share a lot of the same engineering technology (very hot compact core, solid moderator, very high neutron flux, low neutron surplus etc.).
The Russians have a couple of fast sodium-cooled reactors, the BN-600 and BN-800 which produce power, breed new fuel and burn waste but they are still very much beta-level designs. They might be useful in another fifty or sixty years when mined uranium becomes more expensive.