@Jabbers The Fukushima plant was outdated, having been first commissioned in 1971 (meaning at the time of the accident, it was 40 years old and the technology for nuclear plants had moved FAR beyond it's design specs). It was granted permission to operate for another 10 years just a month before the disaster struck (despite numerous faults pointed out by the regulatory committee) in what seems to be a form of regulatory capture. This came about because there's public pressure not to build new nuclear reactors, which in turn forces the nuclear power companies to lobby the government in order to keep older power plants running, as the public pressure makes it much harder to build new plants.
The "intelligent" approach that the Japanese took towards earthquake safety involved:
1. Stress cracks in the backup diesel-powered generators at Reactor No. 1 at the Daiichi plant (the cracks made the engines vulnerable to corrosion from seawater and rainwater).
2. A general struggle to keep the reactor and spent fuel pool from overheating and emitting radioactive materials before the earthquake.
3. The company admitting that it had failed to inspect 33 pieces of equipment related to the cooling systems, including water pumps and diesel generators, at the power station’s six reactors.
4. Regulators saying that “maintenance management was inadequate” and that the “quality of inspection was insufficient.”
5. Small suppression chambers, which increased the risk that pressure would build up within the reactor, a fault eliminated in newer reactors.
Among many other things.
It's entirely possible to build a reactor that cannot go critical. Here's an example:
https://www.forbes.com/sites/jamesc...ear-reactor-that-wont-melt-down/#1d89b8a35b7e
Another example would be thorium reactors, which still require R&D but are much safer than the old power plants as well, for example: "Liquid fluoride thorium reactors are designed to be meltdown proof. A plug at the bottom of the reactor melts in the event of a power failure or if temperatures exceed a set limit, draining the fuel into an underground tank for safe storage." Thorium also produces much less nuclear waste (I've seen up to two orders of magnitude less quoted) and the radioactivity of that waste drops down to safe levels within a century or so, compared to literally tens of thousands of years for other reactor waste.
The problem with nuclear is not about nuclear. It's about public perception of nuclear. Coal pollution kills hundreds of thousands worldwide annually (contributing to 4 of the 5 leading cause of death: heart disease, cancer, stroke and chronic respiratory diseases). Green energy, such as solar power and wind power are where we should be headed, but we likely aren't going to get to where we need to be with them in order to sustain a moderately similar lifestyle before climate change kills us all. The only real valid solution is nuclear energy, at the very least as a bridge between where we are now and where we want to be with green energy.