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...
Well their should be backup generators then. From the news reports I saw it said that both the main pump and the back up pump had been damaged and were not working. This is the first I have heard that the generators were all that wen't down. If that were the case wouldn't the pumps be able to cool the reactor as soon as they were turned back on?
The situation has to be very serious considering the staff were evacuated, some returned for a so called suicide mission. But if the plants workers are leaving and helicopters are beeing called in to dump water on the reactors and fire trucks are doing likewise. It really doesn't sound like the situation is under control or as bad as the american situation.
Also sure you can't close plants over night, but the Japanese Government knew that this plant was to old. Newer plants were built to sustain earthquakes. The Government knowing this facility was out of date and a threat to the public should have closed it. Sure electricity might have been more scarse but look at the situation now, was it really worth this possible meltdown?
Personally I am for Nuclear power, as long as their are enough fail safes and safety measures in place to protect the populous. In the case of Japan, their were not enough fail safes and the facility was known to be too old. If I were in Japan or any other country with a known plant that isn't up to date and code. Yes I'd be against Nuclear Power in those cases.
"In God We Trust - In Games We Play " - Joel Reimer