I didn't say anything about "completely eliminating the possibility of failure". I said "completely eliminate the possibility of meltdown" which is in fact correct.
ThorCon plans on operating the plants about 100 feet underground, which will even mitigate a deliberate attack with an airliner. There is no way to make anything absolutely, 100% safe, but this approach is mighty close.
That is in contrast with fossil fuel pollution, which kills hundreds of thousands of people a year.