The problem with fault tolerance is that it allows the normalization of deviance, since something is always failing, but it's okay because there is always a backup (until there isn't).

The bigger issue with nuclear power is that we can trust humans to keep up the level of effort to keep it working without a fault for a few decades, maybe centuries if we're lucky, but there's no way you can operate a plant for a millennia without a catastrophic accident, but accidents take much more than a thousand years to clean up. So it's all totally imbalanced unless you just assume we'll have fusion in fifty years, so nothing matters. But I don't think we can assume that anymore.