blog #5

Fukushima vs. Chernobyl–Comparison less useful than ever

Nowhere near Chernobyl. Except sort of. But really, much, much less bad. Or… maybe worse.

If your head’s hurting right now trying to keep track of official evaluations of the scale of the Fukushima nuclear disaster, well, get in line for the aspirin. If not yet the iodine pills.

For weeks we’ve been told that the still out-of-control nuclear mess at the Fukushima-Daiichi plant would ultimately come nowhere near the scale of the 1986 Chernobyl disaster. (I wrote about this comparison—and its shortcomings—last week.)
(Fukushima nuclear power plant following the March 11 earthquake & tsunami. Photo: daveeza/Flickr)

The Japanese government, for instance, had rated the accident at level 5 on the IAES’s International Nuclear and Radiological Event Scale—an “accident with wider consequences,” roughly on par with the scary but ultimately fairly limited Three Mile Island event in 1979.

Then on Tuesday, we here in the US awoke to news that Japan has re-evaluated the amount of radiation released so far, and has recalibrated the disaster as a 7—top of the IAEA’s scale, a “major accident,” and a level previously reached only by… Chernobyl.

The announcement was widely reported in leads and top graphs in ways that strongly suggested Fukushima is, in fact, comparable to Chernobyl. (See NYTimes, NPR, Kyodo News, NHK.)

Yikes.

But hold on, they told those of us who weren’t too stunned to listen or read further, Fukushima still has released only about a tenth of the total radiation released at Chernobyl. So even if it’s on the same level as Chernobyl it’s still “totally different from Chernobyl,” according to an official of Japan’s nuclear agency.

OK, so it’s the same, but actually not at all the same.

Turns out the confusion partly results from an imprecise measurement system that doesn’t distinguish between events on the top end of the scale. And there IS a very important distinction here—between a Chernobyl reactor without a containment vessel that exploded and burned for two days, spewing high levels of radiation over thousands of square miles, and the four reactors at Fukushima that have so far suffered much less damage and the impact of which has been much more localized.

Except… on the heels of the government’s announcement that Fukushima is not on par with Chernobyl came this, from an executive of the Plant’s owner, Tokyo Electric Power:

“Our concern is that it could eventually exceed Chernobyl.”

Huh?

Aside from that single quote from TEPCO’s Junichi Matsumoto, I haven’t been able to unearth any more details about this statement, certainly nothing about the level of probability behind it. And the same Japanese nuclear official who said Fukushima is totally different from Chernobyl, despite the top-level crisis rating, told the New York Times, “I cannot understand their position.

So for the time being we’re again left in the dark. Which has been one of the biggest problems of this whole crisis—a dearth of detailed and reliable information, or context for the information we do have.

Some of this may be impossible to get for years, if ever—many instruments are broken or unreliable after the quake and tsunami, and the reactor cores are still too hot to for anyone to be able to assess them directly. It’s also impossible to measure radiation in every possible place it could have ended up. But some information may also have been withheld or massaged by TEPCO or the Japanese government, which has been wrestling with the challenge of how to manage the situation without causing panic among its people.

As I said, we do know that the dynamics of the Chernobyl incident were very different from those at Fukushima. We also know that Fukushima has been managed far better than the Soviets handled Chernobyl (not well, perhaps, but still far better). That means many fewer people have so far received acute doses of radiation this time, and that the fallout from the airborne releases seem to be much less and far more localized. And the Japanese government says that a month now into the crisis, the chances of another large burst of radiation are “significantly smaller.

But we also know that along with the airborne releases, large amounts of radioactivity have seeped into the ground and been released into the sea, much of which, it seems, is as yet uncounted. And of course the disaster is still far from over. Radiation may continue to escape for weeks or months to come.

And amid the mixed signals, here’s one more: even as the risk of significant new releases seems to be diminishing, the Japanese government this week expanded the evacuation zone around the plant to include new areas where residents are likely to receive long-term elevated radiation exposure. It’s also becoming increasingly clear that some of these areas will be uninhabitable for at least several decades to come.

So—Fukushima like Chernobyl? Fukushima NOT like Chernobyl? I still believe the comparison is inappropriate no matter how the numbers do or don’t stack up (Are we comparing the nature of the accident? Total radiation released? Area affected? Total impact on human health?) But it’s clearer than ever this week that that’s a losing rhetorical battle, even as it’s also clear that the comparisons are more meaningless than ever.

But I sure do hope that at the very least, the IAEA will change its scale before the next nuclear disaster—this is becoming harder than ever to characterize for a general audience.

If they don’t, we’ll know that they really are in cahoots—not with the nuclear industry, as many allege, but with the aspirin manufacturers.

Peter Thomson is the environment editor at The World.

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This entry was posted on Wednesday, April 20th, 2011 at 5:01 PM and is filed under Blog. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.



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