1) The actual reactor is about 30 feet below surface level
2) Everything is triple redundant
3) The cement walls are 6 feet thick, steel re-enforced
Any questions?
The only risk is that the shaft from an engine (made of titanium) would go through that cemement like a hot knife through butter. There are no tests that I know of that test this. But even if it did, the reactor would easily be safe and it would immediately be shut down. Everything would in fact be contained.
What is sad is that new reactor designs are tons safer than 30 years ago. And they are now the same thing. There are not custom for each plant. mking them cheeper to make and even safer as iissues are found. Fixes can be made to all plants since they are identical. This country needs to pull it's head out of it's a$$ and get educated on the matter.