I've studied a lot about nuclear technology as one of my hobby interests - from the bombs, the various tests, the accidents, and the development of nuclear power (both weaponry based and power-plant based) and the explosion at the Fukushima I is not good... I know that belabors the obvious. Stick with me here...
What I'm saying is that core is exposed at this point. I know it is - it's not been reported as such, as the explosion just happened a few minutes ago, but this is a technology I know relatively well. Reassembling what we know now, I can back into that conclusion:
Cesium has been detected outside the plant, and that means either meltdown has occurred, or has a strong chance of occuring. Early reports are a fire truck is dumping water on the building. The only hope is that meltdown has not yet happened and the truck can reduce the temperature, resulting in a giant pool of radioactive water and pollutants. That's the best case, and the best case seems to portend disaster.
When the building housing the reactor goes because of pressure, it's destroyed the containment vessel. Venting could be the source of the cesium, but those systems are supposed to be able to handle sequestration of that kind of thing, from what I understand. The reactor was SCRAM'd at the time of the earthquake roughly 24 hours ago, which is an attempted shutdown and mitigation of heat, but it does not reduce the heat to zero. Cooling is required even when shut down.
Exposed or unexposed the cesium came from somewhere.
Clinton says we delivered coolant via the air force. The air force denies this. It's embarrassing because the coolant in this type of plant is water. We ... delivered water from halfway around the world via our air force? If it is true, or even if it is an error, either way can we look more foolish?
It doesn't matter now - we just have to hope Fuk II doesn't go. It's about 19 hours behind the first one's cooling problem. It was also SCRAM'd, but it's tough to tell on the outside if the explosion in I was caused by a procedure or if it was an unforeseen or unavoidable event. I'm working with a personal level of knowledge far short of being able to speculate there.
I'm sitting in my office stunned. This is a TRIPLE redundant reactor. All three defensive layers have failed. 1: primary pumps using power from any reactor, meaning all reactors would have to be shut down (statistically an earthquake-only event) 2: diesel power for pumps failed, 3: battery backup for pumps offline. From what we now know, none have worked due to massive flooding. It proves that you don't need three systems to fail, but rather, you need one failure in common among the three systems. Such an event is very difficult to anticipate.
The real question is: if all three can fail at one core, what is to assume any other core at the facility is not also suspect? This is not Russian made, it's precision made (sorry to say, Russians). It's an older model, but this is a completely safe style of western reactor that has had some features added over the years. We're talking about a one in a million scenario here, and the odds may be even longer than that. Even the NYSE got hit and destroyed by two airplanes on 9/11 and was up two days later - NYSE doesn't have the level of statistical protection that this plant has.
As an engineer, this boggles the mind. All we can do is watch ...
Oh, and sell GE stock .