An obvious question not asked is if these mobile diesel generators were trucked in why is it they did not work? Was it really because the plugs did not fit? After three days they couldn't get adapters to go from one set of connectors to another? After three days they couldn't find a diesel generator of the same type they used at the plant? After three days they couldn't figure out a way to cut off the connectors and splice the cables directly together?
best answers I have so far: All Diesel generators had been on ground level, protected by a low Tsunami protection wall. This wall was strong enough to withstand the water and designed for the worst known tsunami, but not for a kilometer long and 10m high wave. When the power from outside was cut by the tsunami and Earthquake damage, the Diesel generators got started, but quickly failed because of water damage in their compartment.
About the rest, that isn't that easy. Especially for AC, you need the right voltage and the right frequency and the right set of phases. On a good day, when everything works, you can produce any adapter for compatible currents in a few hours.
When your metal workshop is out of electricity like the rest of the place, you can't.
Also, getting mobile generators from another part of the country there, isn't easy at all, you can see the damage to roads there. Such generators are also too heavy for transport helicopters.
Really, it is too easy here to say what should be done, especially if your thinking is still quick to assume normal infrastructure everywhere. The situation is much worse. The reactor is just what you look at because it is the most scary thing that can get worse in the next days, but in reality around the powerplant, the country was shaken back into the 19th century.
And what you imagine as nuclear powerplant from afar, looks more like Stalingrad 1943 from up close because of the Tsunami damage. Inside everything is likely only lightly damaged, but outside you have chaos, that will take months to repair and clean. You could have a dozens of mobile generators on the site, but in the worst outcome of such a tsunami, they are stuck in meters of sticky mud, waiting for a excavator to permit pulling them into the workshop or junk yard.
The situation is more comparable to Apollo 13. But the crew is in this case a whole country, and mission control is sitting on-board.
(the grim circumstances of it all notwithstanding ofcourse)
