I don't think he gives the worst case scenario, which is meltdown by all six of the reactors. It would be nice to know how bad that would be. I would also like to know the physics behind the halt of the meltdown: does it stop because the reactor core breaks apart, thus stopping the chain reaction? Or is it something else?

The situation got worse today as plant #4 caught fire. I suspect that this will affect the world economy the same way the unification of Germany, namely, that Japan will become a sinkhole for capital demand, drying up capital in the rest of the world and restarting the recession.

There's a Wikipedia article on nuclear meltdown, although it's a bit technical. I'm obviously not an expert, but I guess the main question is not so much in how many reactors a meltdown occurs, but whether the containment remains intact. If it does, the consequences will be limited; if the containment is seriously damaged either by an explosion or by nuclear fuel melting through things will get much worse - although not quite as bad as Chernobyl, where in addition there was a graphite fire dispersing the radioactive materials into the air. In that sense, maybe an even bigger concern at Fukushima is a fire at the spent fuel pools.

Well, the actual chain reaction has stopped when the reactor was shut down during the earthquake. There's apparently a theoretical possibility that it will restart if enough nuclear fuel lumps together to form a critical mass - I've no idea how realistic that threat is, but I guess this would be a worst case scenario. Otherwise I assume the meltdown will stop when the material has sufficiently cooled down, whenever that will be.

Thanks LF. I just read a news dispatch that says that if the spent fuel pools burn, cesium 137 could contaminate the Japanese countryside. An ABC News report says that event could render "thousands of square kilometers permanently uninhabitable." Whether that means "it could rain tomorrow" or "it could rain dollar bills tomorrow" I don't know. Apparently the situation is gettting considerably worse--reactors five and six are now registering rising temperatures, even though they have been shut down for months.

Thanks also for clarifying the part about heat the chain reaction. I just assumed that the heat came from the reaction continuing.

To be clear, while the actual chain reaction has been stopped, there's still heat being generated from secondary radioactive processes, which is causing the meltdown. This should decrease exponentially over time, but how fast doesn't seem entirely clear. Initially some experts thought this decay heat should sufficiently decrease to halt or at least slow down a further meltdown after three or four days, but apparently that was too optimistic, for whatever reasons.

Thanks LF. I guess that the heat must dissipate very slowly from a uranium core, which makes sense considering the density of the metal. I know that it takes days for a large bronze statue to lose the heat from casting. I just assumed, wrongly, that the heat came from on ongoing chain reaction.

A bit of radiation is good for you says a scientist, doctor, radiation specialist, geneticist, conspiracy wingnut hate-mongering author.

And she infects her austral counterpart. Truly, the idiocy is strong in this one.

Thought I'd throw in PZ's interpretation for the lay person and why Coulter is "...using a childish, lazy interpretation of a complex phenomenon to tell people lies". Oh say it isn't so...an extreme right-wing fanatic fundamentalist is lying again--it's just not possible...have we ever seen such chicanery before? Oh, right, oops, pathetic, sigh....

The brilliant award-winning science blogger Ed Yong has posted quite a few good links to explanations of what is happening in the reactors, and in Japan itself from the quakes to the tsunami to the politics.

And Ken, I will take your "pathetic", and raise you a person who has **very sadly** deceived himself.


Chess Fan

Chess Fan, your previous post does not make you look good at all. Believe me.

A radiation chart showing the different levels of radiation and how they compare to each other. Puts radiation doses in perspective. Covers the "nothing to worry about" to "RUN FOR YOUR LIVES!" scenarios. At the low end, you get a radiation dose from sleeping next to someone...and eating a banana gives you twice as much radiation as that--The high end is 10 minutes next to Chernobyl as it was melting down.