Ahh Fukushima is a mess. As far as I understand, the tsunami broke the external cooling system (sea water in that case). This caused the reactors to melt down, thus breaking the ducts of the cooling circuits and mixing the flows. Then they pumped water to cool the reactors when everything was already broken. And finally there are leaks from soil water and from rain. All this they have tried to keep in pools for years, but now there is no more space left.
@reignasi @zleap @davidho @Lazarou Not quite. The quake caused the operational reactors to scram (shut down) in good order. But the tsunami overtopped the sea wall and flooded the diesel fuel store for the standby generators needed to keep coolant circulating while the reactors cooled down (it takes months). And the quake took down the grid interconnect. If they'd been able to restore grid power or truck diesel in within 48 hours the meltdowns could have been averted.
@zleap @davidho no, the river water is not too warm to cool reactors. It's too warm in the sense that after cooling the reactor, it would be returned to the river too hot for wildlife. A nuclear accident is not at stakes at the moment, but a huge ecological problem is.