Let me say this once and for all: Fukushima will not be a Chernobyl 2.
And I'm not just saying this to make you (or me) feel better. I say it based on information provided to me by Japanese authorities, and analyses of this info from specialists from several diplomatic missions in Tokyo. I learned more abour nuclear physics (chemistry?) yesterday than I ever wanted to. Let me try to put it in layman's terms, as it has been explained to me.
First of all, the Fukushima reactors do not contain burnable material. The problem in Chernobyl was that the reactor overheated, started a fire which burned for days, and the smoke from the fire spread radioactive material over vast areas. In Fukushima, no such fire is possible.
Secondly, the explosions that have occurred were scary, but not as dramatical as certain news channels (and Twitter) claimed. It was not - I repeat not - a nuclear explosion, and it did not take place in the actual reactor. During a controlled venting of the containment vessel for the reactor in Unit 1 of the Fukushima power plant, hydrogen gas leaked. This gas is explosive when in contact with oxygen. Thus when it leaked further into the operational floor of the unit, it came in contact with the air there, and exploded. This is what blew the roof off the building. Four people were injured, and some (but very little) radioactive material was released, in amounts so small that it amounts to no more than what you are exposed to during a regular x-ray. Also, the containment vessel of the reactor is intact and suffered no major damage, and there is no indication that the actual nuclear core is damaged. It does appear that the second explosion (Unit 3) was similar (and this time expected, although obviously still not wanted) to the first one, and we have received no indication that the situation is more severe as a result of the second explosion.
Both the reactors have also been cooled down, by use of seawater. This means two things: first of all, the reactor is forever ruined, and cannot be put to further use. This is doubtlessly a tough decision to make, not only because of the value of the reactor itself, but also because the temporary termination of the nuclear power plants have created a power shortage here, and that in turn affects the reactors that depend on pumps to cool it down.
Secondly, it poses challenges because there now will be contaminated sea water that cannot be returned to the sea. Japanese authorites have confirmed they will not do that.
These are severe problems, and Japanese authorities are aware of them - but they are still not in the Chernobyl range. We have all seen disaster movies. It is easy to imagine a "worst case scenario" much more bleak than what actually is likely, or even possible. I have asked our expert all sorts of questions, ranging from what the actual (as opposed to media) worst case scenario is; how likely this is; (selfishly) whether this would affect Tokyo; and so on.
His answers have been reassuring. He does not believe an actual meltdown will happen, based on the current information we have available. It seems that the reactors have been cooled down, and they are monitoring further activity. The sea water that has been used to cool down the reactors have been infused with borom, which kills nuclear reactions. Both of these things are good news, since it decreases the likelyhood of a meltown.
Even if a meltdown were to happen, though, the effect would be much smaller than Chernobyl. At the moment the emissions we should worry the most about are probably the contaminated sea water and how it is being handled.
Because of the nuclear power plant shut-downs Japan is facing an energy crisis. We are urged to save power, and the energy company has organized "brownouts" - rotating blackouts to ration power. This is inconvenient, but again I am fortunate to be at the embassy where we have a generator so that we can keep contact with the world. For the time being, I have no plans of leaving Tokyo.
As you may have noticed, I've returned to my regular "on"-titles today. Not because I don't believe we are still very much in a state of emergency - we are - but we still have to try to move towards some sort of normalcy, or we wouldn't be able to cope. The last few days I've had very little sleep, I've been eating irregularly, and I've been under more stress than I've experienced in my lifetime. The combination is not the best; like everyone else here I am exhausted. I try to look at the Japanese. They are worried too - obviously - but they are handing this very well. They go about with their usual business if possible, and listen to authorities for advice. Training since primary school and an orderly nature helps. The only people I've seen freaking out over any of this, have been foreigners. I believe the rest of the world has much to learn from Japan when it comes to coping with crisis.
And yet. I'd be lying if I said I wasn't worried. No, I don't believe we face nuclear meltdown. But yes, it is a grim situation. Despite my rational explanation above, I cannot pretend that I am not affected. It feels oddly like living in the aforementioned disaster movie. I feel that we by now have come to the stage where either a superhero or a rescue team of astronauts or something should arrive and save the day. I'm about ready for the end credits.