The nuclear disaster at the Fukushima Daiichi plant has leveled up to a 7, or “major accident,” topping out the International Nuclear and Radiation Event scale. That puts it in the same category as Chernobyl, the only other level 7 event in history. Does this mean it's time for us all to put on our radiation hazard suits?
Not as bad as Chernobyl: Yes, it's in the same category as Chernobyl, but Hugh Laurie is in the same tax bracket as Bill Gates. There's no level above 7 on the INES scale, so all the bad accidents are gonna be chilling there together, even if some are way worse. And Chernobyl was, in fact, way worse than Fukushima. The accident there killed 28 people immediately and 15 later, as opposed to Fukushima's zero (so far). And so far Fukushima has only released 10 percent as much radiation as Chernobyl. That's enough to get it into the top bracket, but not the top of the chart.
Not getting worse: The change in level doesn't reflect new dangers, just new information. Japan's nuclear regulatory agency has found that at some point in the last month, the plant was releasing 10,000 terabecquerels of iodine-131, and about 500,000 terabecquerels have been released over all (don't worry about how much a terabecquerel is; that's a lot). That's enough to edge it into level 7 territory. But it's releasing less than 1 terabecquerel now. That's still a lot, but it's also a lot less.
Still pretty bad, y'all: We're hardly going to say that this accident is no biggie. It is, by definition, major. But it's not on par with Chernobyl, and it's not worse today at level 7 than it was yesterday at level 5.