My previous post gave several details regarding the problems that are plaguing the Japanese nuclear power plants right now. I wanted to add one bit of information that I learned this morning.
It turns out that the Japanese nuclear reactors did have diesel generators as a backup system. So when the earthquake took out the nation’s power grid, the cooling systems were running fine off their diesel generators. If that were the end of the story, there would not be any serious nuclear-power-plant problems now. Unfortunately, when the tsunami hit later on, the saltwater infiltrated the generators, making them nonfunctional. That’s when the plants had to switch to battery power.
So it turns out that it took a “one-two” punch to put the Japanese nuclear power plants where they are now. The earthquake by itself wouldn’t have been a problem for the power plants. It was the earthquake followed by the tsunami that did them in.
One question: Forget diesel and forget batteries, how come the nuclear stations can’t power themselves?
I can always count on you for excellent questions, Josiah! The problem is that all commercial electrical generators (coal, natural gas, whatever) send their power directly to the grid. The grid then distributes it. So in a sense, they are powering themselves. When the grid went down, there was no way to get the power from the station to the coolant system. If you are thinking of just connecting a cable from the generator to the cooling system, it doesn’t work that way. Think about trying to take a drink from a firehose, and you get an idea of what that would be like for the systems that operate the cooling system.