Last year, the Japanese government ordered the nuclear authorities to conduct tests on all Japan's reactors after the 11 March meltdown at Fukushima Daiichi raised questions about the safety of nuclear power, particularly in a country prone to earthquakes and tsunami.

Earlier this week, a team of experts from the International Atomic Energy Agency [IAEA] began a review of the safety tests but said it was up to the Japanese government whether or not to approve the restart of idle reactors.

Currently only three of Japan's 54 reactors – just over 6% of its total nuclear capacity – are in operation after the Fukushima accident forced the closure of active reactors for safety checks.

The Ministry of the Environment on Jan. 26 announced a schedule for decontamination work covering 26,700 hectares of "special decontamination areas" tainted with radioactive materials from the damaged Fukushima No. 1 nuclear plant.

The schedule eyes completion of decontamination work in areas where the yearly radiation dosage is below 50 millisieverts per year by the end of March 2014. However, the effectiveness of decontamination efforts is still unclear and there are a host of issues to deal with after the decontamination work is finished, including the building of infrastructure for each community. It remains unknown whether residents will be able to return to their homes.

The government's schedule does not clarify the targets for reducing radiation levels. The results of model decontamination work that the Cabinet Office is handling are expected to be released in February or March, and the Ministry of the Environment plans to wait for those results before deciding on targets.

The Japanese government is launching a large-scale cleanup of the fields, forests, and villages contaminated by the Fukushima nuclear disaster. But some experts caution that an overly aggressive remediation program could create a host of other environmental problems.

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Ten months after the nuclear disaster, trust in the authorities is nearly nonexistent. Without it, Japan’s government risks the biggest cleanup fiasco of all: a decontamination effort that carries huge financial and environmental costs but still fails to convince Fukushima residents that their homes, farms, and forests are safe once again

According to a report this week by the International Energy Agency, which isn't an especially alarmist body, the chances grow every day that the world will warm by more than 2C (4F), which scientists estimate is the limit beyond which change becomes chaotic and unknowable, and much more dangerous. To stay within that limit, the proportion of carbon dioxide in the atmosphere mustn't exceed 450ppm (parts per million). Its present level is 390ppm and last year, despite recession, more carbon dioxide from fossil fuels poured into the atmosphere than ever before. The world goes on gobbling up oil, coal and gas in increasing amounts and will continue to build power stations and steel mills that depend on their energy. "Fossil fuel lock-in" is the term, meaning an ongoing commitment to coal and oil that will be impossible to undo until long after 2020, which, according to climate science, is when carbon emissions need to start their decline.

Tepco said that the Daiichi reactors were emitting about 200 million becquerels of radiation per hour as of mid-September, about one four-millionths of the amount seen in the days after the March 11 disaster. It said this translates to about 0.4 millisievert per year of radiation measured at the fringes of the plant, below the 1 millisievert legal limit. [...] Temperatures at all four of its spent fuel pools had fallen to levels considered stable by August. As of Tuesday temperatures at all the spent fuel pools were below 40 degrees.

Japan's nuclear safety agency today rejected a claim in British newspaper The Independent that the earthquake itself, not the subsequent tsunami, destroyed cooling systems leading to meltdowns at the Fukushima Daiichi nuclear plant. [...] An IAEA spokesman said that a report from the mission – led by Mike Weightman the UK's chief inspector of nuclear installations – contains detailed accounts of the failure of cooling systems in the early hours of the disaster which challenge the idea that the quake caused the damage, as claimed in The Independent. Meanwhile, TEPCO said on Wednesday that overall radiation released from the three damaged Fukushima reactors is now a 10-millionth of peak levels recorded on 15 March, just after the accident.

Tests conducted by Minamisoma on about 900 residents showed low levels of internal radiation exposure and no one required immediate treatment, despite the city's proximity to the leaking Fukushima No. 1 nuclear plant, municipal officials said Saturday.

When converted to exposure over the next 50 years, one resident measured just above 1 millisievert of radioactive cesium, while tests on most of the other residents revealed exposure of 0.1 millisievert or less, they said. The maximum radiation exposure limit for a person not involved in nuclear-related work is 1 millisievert per year.

Kyodo News tweeted this morning that the number of foreign visitors to Japan dropped 62.5% in April. This, if true, is a shame, because the ailing Japanese economy (which was already in terrible shape before the earthquake) really could do with the money those visitors would have spent. A lot of them probably stayed away out of a fear of radiation. That’s worse, because then they stayed away unnecessarily.

Most foreign visitors go to Tokyo or Kyoto. Both these places are well out of the way of the radiation from the Fukushima power plant.

But haven’t elevated levels of radiation been detected in Tokyo? — Yes, but the levels are still much much lower than, for example, what you would be exposed to on a perfectly typical flight on a perfectly normal passenger plane. See, for example, this graph showing the levels of radiation detected throughout a business trip to Japan. The radiation in Tokyo is barely noticeable next to the huge spikes during the times the traveler was sitting on a plane. And those spikes would of course have looked the same if he had flown somewhere else instead.

If you don’t feel comfortable going to Japan right now after all that has happened there recently, sure, don’t go. (But do go later — Japan is an absolutely fascinating country.) Just don’t stay away because you’re afraid of being exposed to radiation. Living on Earth, we’re exposed to radiation all the time, from both natural and artificial sources, and a visit to, say, Tokyo would barely register next to everything else that you are already exposed to and that is very unlikely to have any impact on your health. For a bit of perspective, here’s a nice visualization of radiation from various sources.

Kyodo News tweeted this morning that the number of foreign visitors to Japan dropped 62.5% in April. This, if true, is a shame, because the ailing Japanese economy (which was already in terrible shape before the earthquake) really could do with the money those visitors would have spent. A lot of them probably stayed away out of a fear of radiation. That’s worse, because then they stayed away unnecessarily.

Most foreign visitors go to Tokyo or Kyoto. Both these places are well out of the way of the radiation from the Fukushima power plant.

But haven’t elevated levels of radiation been detected in Tokyo? — Yes, but the levels are still much much lower than, for example, what you would be exposed to on a perfectly typical flight on a perfectly normal passenger plane. See, for example, this graph showing the levels of radiation detected throughout a business trip to Japan. The radiation in Tokyo is barely noticeable next to the huge spikes during the times the traveler was sitting on a plane. And those spikes would of course have looked the same if he had flown somewhere else instead.

If you don’t feel comfortable going to Japan right now after all that has happened there recently, sure, don’t go. (But do go later — Japan is an absolutely fascinating country.) Just don’t stay away because you’re afraid of being exposed to radiation. Living on Earth, we’re exposed to radiation all the time, from both natural and artificial sources, and a visit to, say, Tokyo would barely register next to everything else that you are already exposed to and that is very unlikely to have any impact on your health. For a bit of perspective, here’s a nice visualization of radiation from various sources.

So, let’s suppose the whole of Japan was covered in caesium-137 to give everybody a dose similar to the helicopter crews flying over the Chernobyl reactor core. Let’s further suppose that there was subsequently a tripling of leukemia rates throughout the whole of Japan.

What are we up to? I’ve postulated a ridiculous worst case scenario over a ridiculously large area causing a rate of leukemia way above anything actually measured. The result would be that leukemia would rise to about 13 cases per 100,000 people per year. This is about half the rate of bowel cancer increase that has afflicted the country as a result of shifting from their traditional diet to one with more red and processed meat. It’s about a third of the male rate of bowel cancer.