The Fukushima Dai-ichi nuclear power plant disaster
has been elevated to Level INES 7
—same as Chernobyl
. As an engineer who has worked on critical systems (flight control software), I find I ask myself "what went wrong?". Nuclear power plants are suppose to have several levels of fail safes, with the ability to shutdown the reactor in case something goes wrong. The reactors did shutdown when the earthquake hit. But the cooling systems which are needed to keep the reactor cool while the core is cooling down had a problem: no power. The plant was off-line. They had batteries, but those only lasted a day. They also had diesel generators. But the generators had one problem.
I downloaded a diagram of the plant here
(picture used without permission) and I've circled the generators. Anything jump out to anyone? Both of these generators are on the ground level of the plant. So what would happen if there was flooding, say from an earthquake induced tsunami? A level INES 7 accident apparently.
While I don't know much about the design of nuclear power plant, I do keep asking this scenario question. Reactors are hot—that's where the energy for power generation comes from. Couldn't a system where there is a heat source you're trying to remove heat from create some kind of convection driven cooling loop? You don't need pumps when heat rises. Maybe I'm overlooking something obvious—perhaps the flow rate wouldn't be high enough, or maybe because of the closed nature of the primary head exchange. But this passive cooling method does seem better then a system of pumps that without power can not function. Even if the system had a small generator that used waste heat for backup power.
Nuclear power is no joke. There is an enormous amount of energy locked up in a reactor core. If the energy gets out of control, it's extremely dangerous, and extremely hard to get back under control.
One last note. For the beginning of the crisis, officials and spokesmen continued to say the situation was under control, and that everything was going to be alright. Well being ranked the 2nd worst nuclear disaster in the world (and still not over) says they were not only wrong, but disgracefully, pathetically, disgustingly wrong. I hope this disaster does not contain the number of mistakes and lying like what happened with the Deepwater Horizon oil spill
. Japan is a fully developed nation with a lot of very educated people. But those people can not help if they are being fed misinformation about the unfolding situation.