Fukushima as an Alert Level 7 Accident | AREVA North America: Next Energy Blog


There has been a wave of news stories covering the Japanese officials and scientists moving the Fukushima crisis from a 5 to a 7 level on the International Nuclear and Radiological Event Scale. In doing so they put it at the highest alert level that the 0 to 7 scale uses, just as Chernobyl was also on that highest alert level. Nominally, that puts these two disasters in the same broad category.

Why the recent change? At Wired magazine’s site John Timmers of Ars Technica helpfully explains the cause:

“Previously, the Japanese authorities were rating each reactor separately, and scored each of them as Level 5, which involved severe damage to the reactor core and a limited release of radioactive material. The new score reflects both a shift to rating everything as a single incident, and the recognition that very large quantities of radioisotopes were released into the ocean.”

And they list that “In that sense, the change in score seems completely justified, since large quantities of radiation have been released into the environment, and estimates of the cleanup operation are beginning to run over a decade.”

But then Timmers adds this:

“It may, however, be worth questioning whether the rating system is actually doing what it’s intended to: providing a convenient way of informing the public … All of which demonstrates how most rating scales have limited utility when it comes to extreme events.

We agree, and we are gratified at the voices we have seen calling for precision and accuracy in what this means, even as the sloppier of the mainstream press, and anti-nuclear forces claim that this means that “Fukushima basically equals the Chernobyl disaster in all aspects.” Precision and accuracy matter.

Mark McKinnon, writer for the Globe and Mail newspaper in Canada is one such precise and accurate writer. He has “the little-sought-after distinction of having been to both places.” He states flatly:

“Fukushima isn’t Chernobyl … The situation in Fukushima is dire – and terrifying for those who live in the region – but we’re not yet at the stage where an entire region of Japan needs to be written off for decades or centuries to come, as with Pripyat, the city closest to the Chernobyl reactor in what is now northern Ukraine.”

And his list of key comparisons continues:

“The radiation released since the March 11 earthquake and tsunami is still only about 10 percent of that spewed into the air when Chernobyl Reactor No. 1 exploded. The key difference between the two disasters remains that the four troubled nuclear reactors at Fukushima shut down, while Chernobyl exploded with the reactor still running, causing a catastrophic chain reaction that shot radiation into the upper atmosphere.”

He then uses a term of measurement of a unit of radioactivity known as a “terabecquerel.” For the many of our readers to whom that is a new term, it is defined here. But McKinnon’s comparison measures the radiation released in both disasters:

“Fukushima is reported to have thus far released between 370,000 and 630,000 terabecquerels of iodine-131 … it remains far below the 5.2 million terabecquerels released from Chernobyl. Japan’s nuclear safety commission said Tuesday that most of the radiation escaped in the first hours and days after the tsunami. It estimates the release of iodine-131 has now come down to less than one terabecquerel an hour.”

As we all learn and articulate the lessons of Fukushima, we are well served by maintaining precision and accuracy. And so we wanted to applaud it as we see it. If you have found other good articles you’d want to highlight, do add them to our comments …

Share TAGS: Ars Technica, Fukushima, iodine-131, John Timmers, terabecquerel, Wired Magazine

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