To be honest I am wondering why their aren't more fail safes in place. The news report said their was a back up pump that failed. Why is their only one back-up pump? Another thought, why isn't the reactor and containment facility not built over water? Say you build it above a massive pool. That way if anything goes wrong, submerge the reactor in the pool and their yah go.
As for Nuclear power in many cases its nescessary. Where else is Japan going to get the electricity it needs? Wind turbines could provide some power but not enough to power the country. Their is very little options outside of nuclear. However British Columbia Canada where I live we have wind turbines, solar power, dams and all of those sources provide enough power to run the province and we actually export power.
But could wind turbines and solar panels do enough to power Japan? No I don't think so. Infact could they power the United States? Probably not even with the dams in place.
So I think Nuclear power is a nescassary evil. I think Japan should have closed the Fukushima plant awhile ago. I watched on the news that some of the reactors had already been shut down as they were so old. When your reactors are old like that and the plant is inefficiant you close the thing down.
Uh, well you need power to run the pumps. The earthquake/tsunami knocked out the diesel generators. No power, no...well, nothing. That brings up the fact that the pumps are there to circulate water through the fuel cell assemblies, which is enclosed in a shield tank. It's going to be pretty hard to move the reactor vessel and submerged it into the tank which I can't comprehend how that would work as you need to circulate the water through the vessel for effective heat transfer removal. Fuel matrix temperature can go up to 2000 F (and even higher than that). Plus, you would also let fission products into that pool (that's assuming you exposed the core to the water, and that's going to be a lot of radiation released).
Yes, the plant was to be shut down but closing plants don't happen overnight. You have to balance everything, including electricity demand, safety, storage, other logistics, etc...