Category Archives: Fukushima

Fukushima

Japan’s new leadership to boost science

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Japan’s Liberal Democratic Party (LDP), which regained power in a 16 December election, finalized a proposal for a ¥10.3-trillion (US$115 billion) supplementary budget on Friday. The supplementary budget, the second largest in the country’s history, reverses the path of austerity followed by the LDP’s predecessor, the Democratic Party of Japan, which decreased funding for some research projects and lowered many scientists’ salaries. Expected to be approved by parliament in mid-February, the supplementary budget aims to decrease energy consumption, encourage environment-friendly industry and give a significant boost to some research fields.

The industry ministry hopes to spur the economy and lower carbon dioxide emissions. To expand the use of electric vehicles (EVs), the ministry will use ¥100 billion to increase the number of EV battery quick-charging stations across the country from the current 1,400 to 35,000.  Another ¥200 billion will give support to companies that reduce energy consumption through co-generation and other measures. The environment agency will put ¥1 billion into the introduction of LED lights on roads.

The development of alternative materials to rare-earth minerals will also receive a boost. With Japan and China at loggerheads over islands both countries claim, China has restricted access to its near monopoly of such minerals.

Of ¥570 billion requested by the science and education ministry, ¥180 billion will encourage universities to commercialize basic research and another 20 billion for induced pluripotent stem (iPS) cell research. That will increase the amount of money earmarked for iPS cell research over the next ten years to ¥110 billion.

Seismic study loses air over wildlife concerns

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Bruce Gibson argues for the use state-of-the-art seismic survey techniques.{credit}screenshot from California Coastal Commission live webcast{/credit}

A California regulatory board on 14 November denied a key permit for a proposed study of under-sea faults near the Diablo Canyon nuclear power plant in San Luis Obispo County. The plant’s owners, San Francisco–based Pacific Gas and Electric Company (PG&E), had designed the project to aid the state in re-evaluating earthquake risks to California’s two nuclear facilities following the Fukushima Daiichi disaster in March 2011.

The California Coastal Commission reached a unanimous decision after hearing hours of testimony from PG&E, interest groups and concerned citizens. Environmental groups such as the Natural Resources Defense Council (NRDC), based in New York City, argued that marine wildlife would be harmed by the use of high-energy seismic reflection — a technique that maps geological structures in three dimensions by shooting intense sound waves into the ocean and measuring their echoes off of geological features beneath the sea floor. The sound blasts, which measure 230–252 decibels at the air gun source, can penetrate 10–15 kilometres into the Earth.

In its own staff report, the California Coastal Commission estimated that more than 7,000 marine mammals — including several whale species, harbour porpoises and sea otters — would be disrupted by the study. “There will be impacts,” acknowledged Mark Krause, director of state agency relations for PG&E. “We believe we’ve mitigated them to the degree feasible.” In recent months, the company had revised the proposal to reduce the survey area and included additional wildlife monitoring efforts.

PG&E has argued that high-energy testing could provide the most detailed maps yet of a complex network of offshore faults near the plant, including the Hosgri Fault, which lies about three miles to the west. But the commission remained unconvinced that the possible benefits of the project outweighed the costs.

“We know that there is potential for very significant marine resource impacts here,” said Charles Lester, the commission’s executive director. “We don’t feel the case has been made that this particular test at this time is needed.”

The commission urged the company to finish analysing other seismic data it has collected using onshore and low-energy offshore techniques in recent years — data that many opponents say could obviate the high-energy tests.

Still, other critics, such as Bruce Gibson, a former geophysicist and a current county supervisor in San Luis Obispo, want to see the high-energy studies carried out but using more sophisticated technology that might collect data faster and with less environmental disruption.

If the company decides to submit a revised plan, it may still need to convince commissioners that the information gleaned from high-energy seismic tests would have practical value.

In her closing comments, commissioner Jana Zimmer questioned whether more detailed maps of the surrounding faults could be used to  improve the safety of the plant, which is currently designed to withstand a 7.5-magnitude quake.

“If we assume that there is a possibility of a disastrous quake — an 8.5 or 9.0 quake — are there design fixes, are there technologies that we know about that are available… that it would be able to withstand such a quake?”  She said that she hasn’t received a satisfactory answer from the company.

Even if not for safety considerations, some scientists saw the project as an opportunity to collect crucial information about tectonic interactions between the Pacific and North American plates, which create lateral motion along several ‘strike-slip’ faults in the region.

“Strike-slip systems are not straight lines on a map and in 3D they’re not simple planes. To understand their complexity they need to be imaged, and this is an opportunity to image one in great detail,” Art Lerner-Lam, deputy director of the Lamont-Doherty Earth Observatory of Columbia University in Palisades, New York, told Nature.

PG&E had hoped to enlist scientists from the observatory to conduct the seismic research using the National Science Foundation–owned research vessel Marcus G. Langseth. If chosen, the scientists would have made the project data publicly available.

Fukushima fish still hot

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{credit}K. Buesseler, Science{/credit}

Data visualization is all the rage these days, but there’s nothing quite like getting the story from points on a graph. In today’s issue of Science, Ken Buesseler of the Woods Hole Oceanographic Institution in Massachusetts provides plots of radioactivity in fish around the ruined Fukushima Daiichi nuclear plant that do just that (click image to enlarge).

The Y axis is a logarithmic scale of radioactive caesium in becquerels per kilogram (Bq/Kg). The dashed line isn’t a trend line, it’s the Japanese government’s limit on what they consider safe levels of radioactivity in seafood (100 Bq/Kg). This data is for demersal, or bottom-dwelling fish.

There’s a couple of things the graph tell us: first, there is enough radioactivity in the fish in Fukushima prefecture to seriously hinder commercial fishing. Second, the radioactivity doesn’t seem to have declined in the first year after the accident.

Buesseler speculates that this is because much of the radioactivity has settled into the sediment around the plant. Caesium 137 has a half life of 30 years or more, and this could mean that fish from the region will be inedible for decades to come.

The plots also raise some worrying questions: if caesium is continuing to enter the ecosystem and will enter it for some years to come, how might this affect things in the long term? What will happen as contaminated fish swim outside the area around the plant? Buesseler believes that understanding the patterns of contamination on the sea floor, and how it enters and leaves the food chain, will be crucial to managing local fish stocks in the coming years.

Hundreds of safety issues found at European nuclear plants

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The Forsmark nuclear plant in Sweden, one of the sites where safety problems were identified.{credit}Photo by Anders Sandberg via Flickr under creative commons.{/credit}

Hundreds of safety upgrades are needed at European nuclear reactors, according to an analysis of the continent’s power plants.

In the wake of the Fukushima disaster in Japan, the European Commission subjected all 145 reactors at EU nuclear power plants to ‘stress tests’ to determine whether they were in any danger. “Practically all” of the nuclear plants need safety improvements, and “hundreds of technical upgrade measures have been identified”, the commission’s report reveals.

Many power plants are also ill equipped to deal with a major disaster, with 24 reactors having no back-up control rooms that can be used if the primary one has to be abandoned. In reactors in Finland and Sweden, the stress testers found staff would have less than an hour to make the power plants safe if they lost power to the cooling systems or the cooling systems themselves.

In 37% of cases, the reactors’ earthquake risks had not been assessed to modern standards, a figure that rises to 43% for flood risk.

However, the commission insisted that the stress tests showed that standards were “generally high”.

Commissioner Günther Oettinger said in a statement: “The stress tests have revealed where we are good at and where we need to improve. Generally, the situation is satisfactory but there is no room for complacency.”

Japan’s nuclear sun to set?

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A week can be a long time in politics, so today’s announcement by the Japanese government that it intends to phase out its 50 remaining nuclear reactors by around the 2030s is perhaps much less of a certainty than it might at first appear. Under the plan, existing reactors would be phased out when they reach 40 years of age so causing a gradual fall in nuclear’s share of electricity generation in Japan, as no new reactors are built to replace them.

Many of Japan’s reactors are relatively young meaning that any phase-out will bite hardest quite a fair bit down the line – see the graph belo,w which gives a snapshot of the age of Japan’s power reactors – leaving potential scope for Japan’s nuclear policy to shift in the future under different administrations, and circumstances. (In passing, several of Japan’s reactors were built in the last decade, and two reactors are under construction, so under the 40-year rule would persist beyond 2040). In contrast, Germany which last year decided to phase out its then 17 nuclear reactors intends to do so by 2022 – see “The knock-on effects of Germany’s nuclear phase-out” (almost all of its reactors were built in the 1970’s and are nearing the end of their lifetimes).

{credit}IAEA{/credit}

Indeed, in the short-term, the pledge to phase-out nuclear energy may provide the Japanese government with political cover to begin restarting reactors, the last of which was shut down in May (see ‘Japan switches off its last nuclear reactor). The reactors, closed for routine maintenance, would usually be reopened immediately after this was completed, but all will need to meet new safety tests and rules to be implemented this autumn before being restarted.

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First nuclear material is out of Fukushima

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{credit}Credit: TEPCO{/credit}

Investigations continue at the Fukushima Daiichi nuclear power plant in Japan, and earlier this week the Tokyo Electric Power Company (Tepco) released photos of the first nuclear material that they’ve actually managed to get out of one of the reactors.

As a quick recap, the unit 4 reactor was shut down when a magnitude 9 earthquake and 14m tsunami struck the Fukushima Daiichi plant on 11 March 2011. It was actually in the middle of refuelling when the emergency struck, and as a result, its old fuel was in a pool atop the reactor, along with a fresh batch. Since the accident, many people have worried that the fuel in unit 4 constitutes a serious safety risk, particularly if there’s another earthquake.

All summer long, Tepco’s been busy demolishing the top of the unit 4 reactor to try and get at the fuel (the reactor was damaged in a fire that may have started as a result of the meltdown at unit 3). In July, the successfully extracted a single fuel assembly, and this week, they unveiled photos of the assembly under inspection.

An assembly is basically a lot of long little straws filled with pellets of uranium fuel. This particular one is filled with fresh fuel, so it’s not particularly radioactive (which is why everyone is standing around it). This one also does not appeared to be damaged at all, which is pretty remarkable considering what it’s been through. There is a little corrosion on the rods, but that could be precipitated iron from the water used to cool the pool, according to Margaret Harding, a nuclear engineer based in Wilmington, North Carolina. There is some debris from the fires and explosions in the bottom of the pool as well.

The condition of the rod is a positive sign: it means that it may be possible to begin unloading the roughly 1,500 fuel assemblies from the unit 4 pool and move them to a common storage area that will be considerably safer than the current location. In fact, workers have already removed the heavy lid of the reactor’s pressure containment vessel to make way for the unloading operation.

Butterflies and balloons at Fukushima

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Nuclear meltdowns make everything depressing, and this week, even butterflies and balloons have seen their normally cheery image marred by radioactivity.

First butterflies. A paper in the open-access journal Scientific Reports shows mutations in butterfly populations around the Fukushima plant, which melted down in March of last year following a major earthquake and tsunami. The paper is impressively thorough: it examined 144 butterflies collected a month after the accident. Although their behaviour was normal, they did suffer from small morphological defects, such as dented eyes and slightly deformed wings (see above). A second examination of butterflies caught six months later showed about twice the rate of mutation.

The researchers also conducted a series of laboratory experiments in which they induced mutations in normal butterflies through radiation exposure. The total dose received by the lab butterflies was 55 millisieverts (mSv) and 125 mSv, and mutations similar to those in the wild samples could be seen in both populations.

The results are consistent with low-dose radiation exposure. As butterflies breed in the radioactive environment, mutations will accumulate in the population. Another study has shown that the number of butterflies around Fukushima has dropped since the accident, and this could be one reason.

It’s bad news for the environment, but should people be worried? Not really. As I reported in May, the vast majority of civilians and workers have received less than 10 mSv of radiation. Those estimates are backed up by a paper out today in the Journal of the American Medical Association showing that 3,286 residents surveyed received less than 1 mSv of internal exposure from caesium-137 six months after the accident (although they admit earlier exposure might be higher).

It is also worth mentioning that people are a lot bigger than butterflies; so even if they do receive higher doses, we wouldn’t expect the same response.

In separate, balloon-related meltdown news, workers have flown a balloon inside the unit 1 reactor in a clever bid to get a better look at it (right, top). By floating it up through an equipment hatch, the crew hoped to get a look at the top of the reactor and the spent fuel pool, which contained used nuclear fuel before the accident and has been the subject of much speculation since. Unfortunately, they couldn’t get all the way to the top because of debris blocking the way. But they did manage to get a look at the fourth floor, and it wasn’t pretty (right, bottom).

There is a very small silver lining to all of this. On the butterfly front, it’s positive that there are scientists carefully examining the ecological impact of Fukushima (this kind of data was absent for years following the Chernobyl accident of 1984). And the balloon shows that the workers at the plant are coming up with creative ideas to try and deal with the situation.

Images: top, Hiyama, A. et al. Scientific Reports 2, 570 (2012); bottom, TEPCO

Japanese science ministry takes partial blame for tsunami and meltdown

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Japan’s ministry of science and education was supposed to be celebrating the 50th anniversary of its first annual White Paper on Science and Technology with the 2011 edition. Instead of a long spread of great achievements by Japanese scientists over the past five decades, however, the document, which was approved by the government yesterday, became the latest mea culpa for the poor handling of last March’s earthquake, tsunami and nuclear accident. The document puts the spotlight on the responsibility of the countries’ scientists and engineers.

Yasuhiro Yukimatsu, director of the ministry’s strategic-programmes division and head of the six-person team that put the 260-page document together, says it’s the first time that the ministry’s White Paper has become a work of atonement.

The list of failings is familiar by now: scientists lacked “fundamental knowledge about the mechanism of ocean trench earthquakes” and didn’t predict the possibility of a mega-earthquake. They underestimated the height of the tsunami and produced a hazard map with a large gap between estimated and actual inundation. Risk-communication efforts failed to prepare citizens for the unexpected.

The document also pointed to slow and inconsistent handling of various crucial endeavours after Fukushima nuclear reactors went haywire: establishing and lifting evacuation zones, implementing radiation monitoring, sizing up the effects on human health, decontaminating the environment and food, communicating risk, and the difficult process of decommissioning the reactors.

Headlines of most Japanese newspapers have introduced the document as expressing, on behalf of the Japanese scientific community, “deep regret”. Continue reading →

World Health Organization weighs in on Fukushima

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UPDATE: Our latest news story discusses the WHO report at length, along with a second study on the exposure levels of workers and other aspects of the accident by the United Nations Scientific Committee on the Effects of Atomic Radiation.


Today, the World Health Organization (WHO) released a preliminary estimate of the radiation dose received by the public as a result of last March’s meltdowns at the Fukushima Daiichi nuclear plant in Japan. Nature has seen a draft of the final report, and it is mostly good news — the doses are very low, and very few cancers would be expected as a result.

Most residents of Fukushima prefecture received between 1–10 millisieverts (mSv) in the first year after the accident, according to the estimate. Those in neighbouring prefectures received between 0.1–10 mSv, and the rest of Japan received between 0.1–1 mSv. These levels are well below the government’s maximum recommended dose of 20 mSv and will cause a minimal increase in cancer risk.

The obvious question is how minimal. According to David Brenner, a radiation biophysicist at Columbia University in New York, a dose of 5 mSv would be estimated to lead to one excess cancer per 5,000 people exposed. Given that roughly 2,000 of those 5,000 people are going to develop cancer anyway, this is a tiny increase in risk, and Brenner emphasizes that the uncertainties in his calculations are high.

There were two areas that were above the 10-mSv range. In the town of Namie and the village of Itate, to the north-west of the plant, residents received 10–50 mSv in the first year. This is because both towns were beneath a plume of fallout from the plant, but still outside the evacuation zone set up immediately after the accident. Residents in these areas remained until a few months later, when they voluntarily left at the government’s request. As a consequence, they received a higher dose of radiation.

Even the worse case scenario — a dose of 50 mSv — poses a fairly minimal risk. However, the models showed that infants living in Namie could have got a higher dose to their thyroid, of 100–200 mSv. That higher dose would be due mainly to radioactive iodine-131 blowing from the plant immediately after the accident. Brenner says a dose of 200 mSv to a female infant under a year old might mean a 1% risk of developing thyroid cancer over her lifetime (by comparison, the lifetime risk in the United States is 0.02%).

It’s important to remember that the WHO numbers are based on models, and real doses would vary quite a bit. A survey of 1,080 infants and children in the area has shown no thyroid doses above 50 mSv thus far. Similarly, radiation surveys of Fukushima residents show very low doses. All of these measurements are consistent with the WHO model.

We’re going to have a much more detailed story on the doses received by civilians and the workers at the plant later today.

Image: Nature (data from: WHO/METI)

Fukushima reports redux

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This week, think tanks and advocacy groups around the world have been producing reports on the Fukushima nuclear catastrophe, which began almost exactly one year ago, on 11 March 2011. Here’s a round-up of what’s come out so far, and what they had to say:

Fukushima was preventable. James Acton and Mark Hibbs of the Carnegie Endowment for International Peace in Washington DC conclude that Japanese regulators and the Tokyo Electric Power Company did not do enough to prepare for the 11 March tsunami. Computer modelling was inadequate, flood defences for emergency systems were weak and bureaucracy made nuclear professionals reluctant to take advice from outside experts.

The response to the nuclear accident was a mess. Yoichi Funabashi and Kay Kitazawa, a journalist and a city planner, respectively, write in the Bulletin of the Atomic Scientists that a division of regulatory oversight, a myth of “absolute safety”, and cosy relationships between regulators and industry laid the groundwork for a sluggish and confused response. Japan’s political leaders were not properly informed as the crisis unfolded, and their resulting confusion slowed critical decisions such as when to flood the reactors with water. Abysmal crisis communication then sowed the seeds of mistrust in the general population.

Regulators must plan for rare events. The American Nuclear Society’s lengthy report contains many lessons for the US industry, but their top-line lesson from Fukushima is that rare events must be factored into safety planning. Japanese officials should have made sure the plant could withstand a one-in-a-thousand-year event like the Tohoku tsunami. The extensive report also suggests possible upgrades to American equipment and training for severe nuclear accidents. But it urges a slow approach to ensure that modifications are done properly to improve safety.

US regulators aren’t doing enough. The Union of Concerned Scientists has harsh words for the US Nuclear Regulatory Commission (NRC) in its report. Although the NRC did respond quickly and effectively to public concerns as the Fukushima crisis unfolded, it has not sufficiently strengthened its oversight of nuclear safety and, specifically, the procedures for severe accidents at US plants. Instead, the US industry has implemented a voluntary safety-improvement programme that may not be sufficient to prevent a Fukushima-like meltdown.

Not everyone has produced a report. The World Nuclear Association, Greenpeace, the International Atomic Energy Agency  and many others have issued statements. And the Natural Resources Defence Council has put together an online tool recreating a Fukushima-like accident at US nuclear power sites around the country.

Last but not least, TEPCO’s regular updates of conditions at the plant continue, as do the reports from the Japan Atomic Industrial Forum.

If there are other reports or statements you think are worth adding to the list, please chime in.

For more on Fukushima and the Tohoku earthquake, check out our Japan quake special.