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Who knew about Fukushima’s radiation?

Integrated dose map (small 2).jpgThere is a report in the New York Times today alleging that the Japanese government covered up information about high radiation levels immediately following the triple meltdown at the Fukushima Daiichi nuclear power plant. It’s interesting enough that it prompted me to take a look at our previous coverage and here are some observations.

The Times story says that Japanese authorities had a computer model called the System for Protection of Environmental Emergency Dose Information (Speedi), which was capable of calculating where the radiation was spreading almost immediately after the accident. Those models later showed a plume of radiation spreading to the northwest, which probably looked quite similar to this recent radiation survey (right). According to the Times piece, Japanese authorities and agencies deliberately withheld the computer model until 23 March, 12 days after the initial incident began. The story gives a muddle of motivations: Some politicians and bureaucrats may have been seeking to protect the nuclear industry; others were trying to stem panic; and still others were just trying to avoid bringing the bad news to the prime minister.

Observation time. First, it was clear right from the start that the government was struggling to communicate with the public. As early as 12 March, deputy prime minister Yukio Edano denied that an explosion occurred at reactor Unit 1 (despite television footage to the contrary). He added that “there is no possibility that radioactive substances will have leaked.”

Second, radiation data was scarce in the first days, but within a week, there were indications that radiation had spread well beyond the evacuation zone. Already on March 17, two days after the final rector exploded, we had a blog post reporting high levels of radiation outside the evacuation zone, and specifically to the northwest. So regardless of whether the Speedi model was available, it was clear that there were large areas outside of the 20 km evacuation zone that were above safe levels of radiation. The problem was that no authorities in Japan seemed to be communicating that to the public.


As an aside, it is interesting that this first data came a day after the US and Britain announced far larger evacuation zones for their citizens. It seems clear now that these countries were using their advice to apply pressure on the Japanese government (even early on, the US stated quite publically that the situation was bad).

As I said in that original post, there were plenty of reasons at the time for holding the zone where it was. Fuel shortages were already reported in Fukushima prefecture, and the government was in no position to help. The radiation doses people were exposed to there were still relatively low, and as I’ve said before, dose over time is the critical factor.

But the government’s failure to communicate did have real consequences. Without any information, some local authorities decided to move away from the plant, and in doing so they may have exposed residents to peak radiation levels. Particularly worrying would be exposure to Iodine-131, which can cause thyroid cancer, especially in the young. Unless the children got sodium iodide tablets (which they may have done) they would have been better off indoors.

The issue of what to do with the radiation now that it’s on the ground has also been in the news. The government has declared anywhere above 20 mSv/year too dangerous to live (yellow and above, click the map to enlarge). Now, the government says that they will seek to halve the areas with radiation levels that exceed the 20 mSv/year limit. That could be a costly cleanup, given the scale of the contamination.

Meanwhile, the Tokyo Electric Power Company, which owns the plant, has reported a Y571.7bn (US$7.4bn) quarterly loss.

Credit: MEXT

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