Richard Black of BBC News suggests that the Fukushima Daiishi nuclear power plant had vulnerabilities that road-not-traveled reactors did not:

Would a newer reactor have fared better? Was the relationship between industry and regulators too close? Perhaps.
A question less often discussed, but equally intriguing, is whether decisions made half a century ago for reasons of commercial and geopolitical advantage have left the world with basic designs of nuclear reactor that are inherently less safe than others that have fallen by the wayside.
To make an analogy with the world of videotape: have we been guilty of rejecting the nuclear Betamax in favour of an inferior quality VHS?

Black goes on to offer a kind of What If? tale of 20th century reactor design, with a brief look at the future.