"there's no such animal as a failsafe nuclear reactor."

There probably can be. Years ago I read a Scientific American article on third generation nuclear plants. The stress was on safety. I'm sure more has been done since that article was written. It might have been 20 years ago that I read it.

One of the designs worked similarly to air brakes on large trucks. When they lose air pressure a spring locks the brakes up. The thing comes to a very, very abrupt stop.

One of the designs I remember had the core and other sensitive components below ground, and a sort of moat, or pond. The operators weren't down there, but the "stuff" was.

If it started misbehaving, the gates to the moat stopped getting the feedback necessary to keep them shut, the plant flooded, and any possible reaction stopped.

I don't know the details, obviously. And, it was designed so that flooding would shut everything down.

Clearly, there would have to be redundancies, feedback, etc. And it should work without too long a chain of things having to happen.

Arf