Open Intelligence / Energy

For India, this is a lesson and an exceptional opportunity to relook at the protected structures of the department of atomic energy (DAE), and establish more transparent processes and procedures.

In the past, the Three Mile Island incident (1979) and Chernobyl accident (1986) had provided similar opportunities to evaluate nuclear safety and regulatory systems. India, in response to these incidents, constituted safety audits to assess the safety of nuclear power plants. However, A. Gopalakrishnan, (a former chairman of Atomic Energy Regulatory Board) in his recent article said, “DAE management classified these audit reports as ‘top secret’ and shelved them. No action was taken on the committee’s findings.”

If this is so, these reports, or at least action-taken reports, ought to have been published and made available. Such steps could have guaranteed DAE considerable public faith in the functioning of regulatory authorities and given significant confidence in engaging with stakeholders in the present expansion plan.

Nuclear Power Corp. of India Ltd, post-Fukushima has undertaken safety evaluation of 20 operating power plants and nuclear power plants under construction. The inm report titled Safety Evaluation of Indian Nuclear Power Plants Post Fukushima Incident suggested a series of safety measures that must be incorporated in all the audited nuclear power plants in a time-bound manner. Measures pertain to strengthening technical and power systems, automatic reactor shutdown on sensing seismic activity, enhancement of tsunami bunds at all coastal stations, etc.

However, in the same breath, the report provides assurance by stating that, “adequate provisions exist at Indian nuclear power plants to handle station blackout situations and maintain continuous cooling of reactor cores for decay heat removal”. Further, the reports recalls, “the incidents at Indian nuclear power plants, like prolonged loss of power supplies at Narora plant in 1993, flood incident at Kakrapar plant in 1994 and tsunami at Madras (Chennai) plant in 2004 were managed successfully with existing provisions.”

DAE’s official response, post-Fukushima, has been cautious while providing assurance. Separately, DAE has made it clear the nuclear energy programme will continue as planned after incorporating the additional safety features identified by the safety audit report.

Prime Minister Manmohan Singh in his speech two days ago in West Bengal was emphatic about the future of India’s nuclear energy programme. He said that “there would be no looking back on nuclear energy. We are in the process of expanding our civil nuclear energy programme. Even as we do so, we have to ensure that the use of nuclear energy meets the highest safety standards. This is a matter on which there can be no compromise”.

S. Banerjee, chairman of Atomic Energy Commission and secretary DAE at the International Atomic Energy Agency Ministerial Conference on Safety, categorically said: “India’s effort has been to achieve continuous improvement and innovation in nuclear safety with the basic principle being, safety first, production next.” This is important at a time when we are in the process of expanding nuclear capacity at an incredible pace.

Currently, there are several domestic and international power projects in the pipeline. DAE has projected 20,000MWe (megawatt electric) by 2020 from present 4,780MWe, a fourfold increase from the current production. Going further, Banerjee stated that India hopes to achieve targets exceeding 30,000MWe by 2020 and 60,000MWe by 2032. This is a tall order, considering our experience in executing major infrastructure projects. DAE has struggled in the past to achieve targets.

Execution of these targets is to be achieved by importing high-capacity reactors and through DAE’s own programme. As we see greater activity in the nuclear energy sector?which was traditionally not transparent in engaging with the public?the trust deficit could only widen as we expand the programme

Land acquisition is already a major concern for infrastructure projects and has become an issue at the proposed Jaitapur nuclear power plant as well. However, the biggest challenge in this expansion would be to convince the public of the safety and security of nuclear power plants and also arrive at a comprehensive information and communication package for states in whose territory projects are being executed. Because of the nature of India’s nuclear programme?the combined existence of civilian and military programmes?the nation may not be in a position to achieve the kind of regulatory autonomy, process and engagement that has been witnessed in many European countries and in the US.

The bifurcation of India’s nuclear establishment into civilian and military, subsequent to commitment under India-US civil nuclear cooperation has provided with the prospect of an empowered regulatory system.

Incidents in Jaitapur and the Fukushima nuclear disaster have further pushed the government to commit to establish an independent nuclear regulator, the Bill of which is expected to be in Parliament any time this year. Nuclear programme is likely to face more complex issues in the future with respect to environment, social and health. Neighbouring countries may also join the chorus soon since some of the proposed nuclear power plant sites are close to our borders

TVA's board of directors approved last Thursday plans to build a new $4 billion nuclear reactor at its “Bellefonte” site. Beside the timing, its dilemma is compounded further because it is a federal agency that has $24 billion in debt, which Congress has capped at $30 billion. So, the additional money cuts things pretty close.

With the cancellation of the Yucca Mountain nuclear waste repository in Nevada, many nuclear operators are loading older fuel into sealed metal casks filled with inert gas. The Massachusetts Institute of Technology will get a grant to study how such “dry casks” perform in salt environments.

The money will go to a variety of projects at 31 universities in 20 states. Several focus on nuclear waste.

Another important concern in the nuclear power field is the aging of reactors. Researchers at Pennsylvania State University will get $456,000 to plan a system that will use ultrasonic waves to look for cracks and other defects in hot metal parts. The idea is to find “microscale” defects that lead to big cracks.

Some of the work is aimed at helping to improve new reactors. For example, a researcher at the University of Houston, with collaborators at two other universities, will study a “base isolation system” that would protect reactors against earthquakes.

In an earthquake, the ground moves back and forth at a certain frequency, similar to the way a gong struck by a mallet vibrates at a given frequency. But plants could be built atop materials with “frequency band gaps,” that do not vibrate at the frequency that is characteristic of earthquakes, the Energy Department suggests.

world leaders are beginning to back away from nuclear energy, some even setting a timetable to transition their country into a nuclear-free zone. In contrast, Taiwanese leaders seem unperturbed and deaf to popular sentiments about nuclear accidents and very intent on making Taiwan a dictatorship and a technocracy.

Beginning October 2011, PCT will host 24 seminars on how to create a nuclear-free Taiwan. The purpose of these seminars is to educate and involve the public by raising awareness on nuclear energy and autocratic governments. The choice before us all is whether to live under the shadow or threat of a nuclear meltdown or to live at ease in a nuclear-free country.

Firstly, 'spent fuel' is defined as fuel whose elements have been removed from the reactor because the fissionable material they contain has been depleted to a level near where it can no longer sustain a chain reaction. The high concentration of radioactive fission products in spent power-reactor fuel creates a gamma-radiation field, which at a distance of a metre would be lethal. South Africa, or more accurately Necsa, no longer has any use for this material.

Secondly, the US and South Africa have been working constructively for a number of years on various peaceful use applications of nuclear material and in particular on the need to minimise the use of HEU. Examples of such co-operation are the conversion of South Africa's SAFARI-1 reactor to low enriched uranium (LEU) fuel as well as training in medical responses to nuclear and radiological emergencies. Indeed, today South Africa is leading the transition to produce the medical isotope molybdenum-99 (Mo-99) with LEU rather than HEU.

Zuma was one of only five African Heads of State or government invited to develop concrete measures towards ensuring that nuclear materials under their control are not stolen or diverted (the others being Algeria, Egypt, Morocco and Nigeria). They pledged to improve security as changing conditions may require, and to exchange best practices and practical solutions for doing so. The Summit's final communiqué also highlighted the fact that 'highly enriched uranium and separated plutonium require special precautions'.

Thirdly, the return is not unique. The repatriation of used and unused HEU fuel to its country of origin - either the US or Russia - has been an international goal since the early 1980s. Some 1,249kg of US-origin highly enriched uranium from sites around the world have already been returned, including from Chile in April 2010 just after the earthquake the previous February.

Finally, and perhaps most importantly, the spent fuel storage facility at Necsa is not, and has never been, 'vulnerable' - in the sense of being in danger of being accessed by organisations or persons with criminal intent or worse, with terrorist ideologies.

Some very low level nuclear waste can go into landfill-type settings. But low level waste consists of low concentrations of long-lived radionuclides and higher concentrations of these short-lived must remain sequestered for a few hundred years in subsurface engineering facilities. Medium-and high-level wastes require placing hundreds of meters below the ground for hundreds of thousands of years in order to ensure public safety. Intermediate waste containing high concentrations of long-lived radionuclides, as high-level waste, including spent fuel reprocessing and fuel waste. Because they are extremely radioactive high level waste that emits heat. There is no repository for high level nuclear waste disposal wherever in the world.

All types of energy production, money is on the front end of the process and of waste management in the back end. Macfarlane argues, however, that a failure to plan for the disposal of waste can cause the most profitable front end of a company to collapse.

Nuclear fuel discharged from a light water reactor after about four to six years in the kernel. This should be cool, because the fuel is radioactively and thermally very hot to discharge, in a pool. Actively cooled with borated water circulated, spent fuel pools are approximately 40 feet (12 meters) deep. Water not only removes heat, but also helps to absorb neutrons and stop a chain reaction. In some countries, including the United States, metal shelves in spent fuel pools hold four times the originally planned amount of fuel. The plans to reprocess fuel have failed for both economic and political reasons. This means that today is more fuel pools from reactor cores, and the fuel endangers big radiation in the event of an accident-loss of coolant, as happened in Fukushima.

Japan’s Fukushima Daiichi plant spent fuel has seven pools, one at each reactor and large shared swimming pool, dry storage of spent fuel on site. Initially, Japan had planned a brief period of storage of spent fuel in the reactor before reprocessing, but Japan’s reprocessing facility has suffered long delays (scheduled to open in 2007, the installation is not yet ready). This caused the spent fuel to build the reactor factory sites.

Countries should include additional spent fuel storage nuclear projects from the beginning, and not the creation of ad hoc solutions, after spent nuclear fuel has already begun to build. Storage location is a technical issue, but also a social and political.

But attorneys for large businesses, consumers and environmental groups question the methodology the energy companies are using and whether customers will actually benefit in the long run.

The state Office of Public Counsel, which represents consumers, argues that FPL’s decisions to “fast track” the new reactors led to inflated costs – an argument FPL disputes. If approved, FPL’s request would result in a $2.09 increase next year for residential customers, based on 1,000 kilowatt hours of electricity usage.

Those connections “run pretty deep,” said Kevin Kamp with the watchdog group Beyond Nuclear. “That begins to explain his policy.” Exelon has had ties to some of Obama’s closest advisers.

That would come on top of the .5 billion currently set aside as part of the loan guarantee program started under President George W. Bush’s Energy Policy Act of 2005. Some critics have charged that Obama’s support for nuclear power Dewalt DC9091 drill battery can be traced to his political rise in Illinois, home to Exelon, the nation’s biggest operator of nuclear plants.

Nuclear power already accounts for 20 percent of overall electricity in the United States, and makes up the vast majority of carbon-free energy. But because the cost of building a new reactor is so high — and Wall Street is reluctant to invest with natural gas emerging as a more viable alternative — utilities have turned to the government for assistance. Obama has signaled his desire to help, proposing in his 2012 budget plan an additional billion in loan guarantees to build new plants.

Exelon’s political action committee and its employees have given more than 0,000 to Obama’s congressional and presidential campaigns over the years, including ,300 from Exelon chief executive John Rowe, according to Federal Election Commission records.

David Axelrod, the president’s longtime political strategist and former White House advisor, has worked for Exelon as a consultant, though Axelrod said Friday he currently has no private clients. Rahm Emanuel, Obama’s former chief of staff and now Chicago’s mayor-elect, helped broker the deal that created Exelon when he worked at the investment bank Wasserstein Perella.

Since Obama became president, Exelon has sided with the White House in at least one major policy battle — quitting the U.S. Chamber of Commerce in protest of the trade group’s opposition to a cap-and-trade energy plan. Exelon declined comment.

Another major nuclear player is Duke Energy, whose chief executive, Jim Rogers, is leading fundraising efforts for the 2012 Democratic National Convention in Charlotte, N.C. The firm, which slightly favored Democrats in its 2010 PAC donations, has agreed to guarantee a million line of credit for the convention from a local bank.

Duke Energy officials say the effort is purely an economic development initiative. ‘We would do it for the Republicans in 2016 if they would consider Charlotte,” said spokesman Tom Williams. “It’s not a partisan effort at all.”

Overall, Obama has not relied very heavily on energy-related contributions in his political career, and his aides have pledged to continue refusing any corporate PAC donations in the 2012 campaign. Contributors in the energy and natural resources sector gave about .8 million to Obama in 2008, compared to .1 million for GOP candidate John McCain, according to the Center for Responsive Politics.

The president’s position appears to be in good stead with crucial independent voters, a majority of whom view nuclear as a safe energy source, according to a new Fox News poll. The survey found that a plurality of Democratic voters disagree.

Last year, the White House rejected a request by Rep. Edward J. Markey (D-Mass.) to enforce a law passed in 2002 requiring that potassium iodide pills be made available to all U.S. citizens living within 20 miles of nuclear plants for use in case of exposure to radioactive iodine.

The new policy was revealed during the meeting of experts affiliated with the Ministry of the Environment on August 27. So far, the Ministry's policy has been to allow the ashes with 8,000 becquerels/kg of radioactive cesium and below to be buried, but require the ashes that exceed that level to be stored temporarily while the Ministry decides on the disposal method.

Under the new policy, if radioactive cesium in the ashes exceeds 8,000 becquerels/kg but does not exceed 100,000 becquerels/kg, the ashes are allowed to be buried after they are bound with cement or put in a concrete container. If radioactive cesium exceeds 100,000 becquerels, then the ashes should be buried in the disposal facilities with a roof and/or with the concrete shield.

Radioactive cesium exceeding 8,000 becquerels/kg has been detected from the ashes from burning the regular household garbage in Kanto and Tohoku regions. The Ministry of the Environment has decided to apply the same rule as the disaster debris and allow the ashes to be buried. The municipalities will be able to bury the ashes that they have stored temporarily, but it may be difficult to obtain consent from the residents living near the disposal facilities.

The number "100,000 becquerels/kg" is significant in a sense, as the highest level of radioactive cesium found from ashes after burning the household garbage is 95,300 becquerels/kg in Fukushima Prefecture (link in Japanese). The number is high enough to clear the Fukushima garbage ashes, and it is probably high enough to clear garbage ashes from anywhere else.

Besides, as the NHK article states, even if it exceeds 100,000 becquerels/kg, all they need to do is to bury it in a disposal site with a roof or the concrete shield. This new policy is to be applied to ashes from disaster debris and regular garbage that are radioactive. It's not mentioned in the article but the ashes and slag from the radioactive sewage sludge will be likely to be disposed under the same policy - i.e. burn and bury. (And remember the "mix and match" scheme.)

In the meantime, some garbage incinerators and sludge incinerators at waste processing plants and sewage treatment plants in cities in Kanto have become so radioactive that they have to be shut down. (More later.) The entire country is to become the nuclear waste disposal site, because of one wrecked nuclear power plant. Talk about socializing the cost.

Around 80,000 people have been evacuated since the March 11 quake and tsunami and many are living in shelters or temporary homes.

The government's announcement follows the release of data this week showing radiation readings in 35 spots in the evacuation zone above the 20 millisieverts per year level deemed safe by the government. The highest reading was 508 millisieverts in the town of Okuma, about 3 km from the nuclear plant. 

The accident at the Fukushima plant is likely to have released about 15 percent of the radiation released at Chernobyl in 1986, Japan's Nuclear and Industrial Safety  Agency has estimated.          But that is still more than seven times the amount of radiation produced by Three Mile Island accident in the United States in 1979, and experts have estimated Japan's decontamination efforts could cost as much as 10 trillion yen ($130 billion).   

On August 15 I wrote about neptunium-239, half life of about 2 days, having been detected in large quantity in Iitate-mura, 35 kilometers from Fukushima I Nuclear Power Plant. I had to take down the second post on the subject, but the information was correct. Now, NISA is suddenly mentioning neptunium-239. Admission of wide dispersion of this nuclide and resultant plutonium-239 may be finally forthcoming, after more than 5 months.

At a staircase connecting a school playground to the street, it found radiation amounting to 7.9 microsieverts per hour, or about 70 times the maximum allowed, exceeding even Japan's own standard.

Greenpeace urged the government to delay reopening the schools as planned on Sept. 1 after the summer break and relocate children in the most affected cities until decontamination was complete. Fukushima city dismissed Greenpeace's calls, saying the schools were safe under the government's norms.

The soil contamination as the result of the Fukushima I Nuclear Power Plant accident was reported on the August 29 meeting at the Ministry of Education and Science.

The survey found 34 locations in 6 municipalities exceeding the level of the confiscation/closed zone of the Chernobyl accident (1,480,000 becquerels/square meter of cesium-137 in soil). The purpose of the survey was to understand the radiation exposure of the residents. Prime Minister Kan said on August 27 that there might be locations where the residents wouldn't be able to return for a long time. The survey data validates the prime minister's comment.

According to the survey, the highest cesium-137 concentration in soil as of June 14 was in Okuma-machi in Fukushima Prefecture, within the no-entry evacuation zone, at 15,450,000 becquerels/square meter. If combined with cesium-134, the radioactive cesium concentration was 29,460,000 becquerels/square meter.

Total 16 location in 4 municipalities (Okuma-machi, Futaba-machi, Namie-machi, Tomioka-machi) exceeded 3,000,000 becquerels/square meter in cesium-137 concentration. The area with the high cesium-137 concentration extends northwest from the nuclear power plant. In total, 6 municipalities including Iitate-mura and Minami Soma City had the locations that exceeded the Chernobyl confiscation/closed zone level of cesium-137. The Ministry measured the soil samples from about 2,200 locations.Here's the map by Asahi Shinbun, including the locations with cesium-137 concentration of less than 1 million becquerels/square meter.

"Cleaning," "waiting," and "dismantling" are the three key actions in this process. Needless to say, this all needs to be done while simultaneously containing radioactive materials.

In the case of the Tokai Nuclear Power Plant, the first commercial plant to undergo decommissioning, spent fuel was removed over a span of three years beginning in 1998, and was transported to Britain for reprocessing. Dismantling of the facilities began in 2001, with current efforts being made toward the dismantling of heat exchangers; workers have not yet begun to take the reactor itself apart. The entire process is expected to be an 88.5-billion-yen project involving 563,000 people.

Hitachi Ltd., which manufactures nuclear reactors, says that it "generally takes about 30 years" to decommission a reactor. The Hamaoka Nuclear Power Plant's No. 1 and No. 2 reactors operated by Chubu Electric Power Co. are also expected to take about 30 years before they are decommissioned.

In the case of the Fukushima No. 1 Nuclear Power Plant, meanwhile, the biggest challenge lies in how to remove the fuel, says Tadashi Inoue, a research advisor at the Central Research Institute of Electric Power Industry (CRIEPI), a foundation that conducts research on energy and environmental issues in relation to the electrical power industry.

"we must deal with rubble contaminated with radioactive materials that were scattered in the hydrogen blasts and treat the radiation-tainted water being used to cool nuclear fuel before we can go on to fuel removal."

Currently, the Fukushima plant's operator, Tokyo Electric Power Co. (TEPCO), is desperately trying to treat the contaminated water. Huge challenges remain with regards to the contaminated rubble, as radiation levels of over 10 sieverts per hour were found near outdoor pipes on the plant grounds just the other day. Exposure to such high levels would mean death for most people.

Each step in the process toward decommissioning is complicated and requires great numbers of people. It's a race against time because the maximum amount of radiation that workers can be exposed to is 250 millisieverts.

The breached reactor core is a bigger problem. It is believed that raising water levels inside the reactor has been difficult because of a hole in the bottom of the vessel. It will be necessary to plug the hole, and continue filling the vessel with water while extracting the melted fuel. How to fill the vessel with water is still being debated. If the reactor can be filled with water, steps taken after the 1979 Three Mile Island nuclear accident can serve as a guide because in that case, in which approximately 50 percent of the core had melted, workers were able to fill the reactor with water and remove the fuel within.

Two types of fuel removal must take place. One is to take out the spent fuel in the containment pools, and the other is to remove the melted fuel from the reactor cores. Because the radiation levels of the water in the spent fuel pools have not shown any significant changes from before the crisis, it is believed that the spent fuel has not suffered much damage. However, removing it will require repairing and reinstalling cranes to hoist the fuel rods out.

Prefacing the following as "a personal opinion," Inoue says: "Building a car that can protect the people inside as much as possible from radioactive materials, and attaching an industrial robotic arm to the car that can be manipulated by those people could be one way to go about it."

Inoue predicts that removal of spent fuel from the containment pools will begin about five years after the crisis, and about 10 years in the case of melted fuel from the reactor core. Work on the four reactors at the Fukushima plant will probably take several years.

"Unless we look at the actual reactors and take and analyze fuel samples, we can't know for sure," Inoue adds. Plus, even if workers succeed in removing the fuel, reprocessing it is an even more difficult task. A review of processing methods and storage sites, moreover, has yet to take place.

Meanwhile, at least one expert says he doesn't believe that workers will be able to remove the melted fuel from the crippled plant.

"If there's 10 sieverts per hour of radiation outside, then the levels must be much higher closer to the reactor core," says Tadahiro Katsuta, an associate professor at Meiji University and an expert in reactor engineering and reactor policy who was once a member of an anti-nuclear non-profit organization called Citizens' Nuclear Information Center (CNIC). "The fuel has melted, and we haven't been able to cool it consistently. If work is begun five or 10 years from now when radiation levels have not yet sufficiently gone down, workers' health could be at serious risk."

Katsuta predicts that it will probably take at least 10 years just to determine whether it is possible to remove the fuel. He adds that it could very well take 50 years before the task of dismantling the reactor and other facilities is completed.

What Katsuta has in mind is a Chernobyl-style concrete sarcophagus, which would entail cloaking the melted tomb with massive amounts of concrete. "How could we simultaneously dismantle four reactors that have been contaminated to the extent that they have by radioactive materials?" asks Katsuta. "Japan has little experience in decommissioning reactors, and this case is quite different from standard decommissioning processes. It's not realistic to think we can revert the site back to a vacant lot. I think we should be considering options such as entombing the site with concrete or setting up a protective dome over the damaged reactor buildings

what we face is a great unknown to all of mankind.

On the other side of the nuclear fence are the industry friendly scientists who insist that the crisis is under control and radiation levels are mostly safe. "I believe the government and Tokyo Electric Power [Tepco, the plant's operator] are doing their best," said Naoto Sekimura, vice-dean of the Graduate School of Engineering at the University of Tokyo. Mr Sekimura initially advised residents near the plant that a radioactive disaster was "unlikely" and that they should stay "calm", an assessment he has since had to reverse.

Slowly, steadily, and often well behind the curve, the government has worsened its prognosis of the disaster. Last Friday, scientists affiliated with the Nuclear and Industrial Safety Agency said the plant had released 15,000 terabecquerels of cancer-causing Cesium, equivalent to about 168 times the 1945 atomic bombing of Hiroshima, the event that ushered in the nuclear age. (Professor Busby says the release is at least 72,000 times worse than Hiroshima).

Caught in a blizzard of often conflicting information, many Japanese instinctively grope for the beacons they know. Mr Ichida and his colleagues say they no longer trust the nuclear industry or the officials who assured them the Fukushima plant was safe. But they have faith in government radiation testing and believe they will soon be allowed back to sea.

That's a mistake, say sceptics, who note a consistent pattern of official lying, foot-dragging and concealment. Last week, officials finally admitted something long argued by its critics: that thousands of people with homes near the crippled nuclear plant may not be able to return for a generation or more. "We can't rule out the possibility that there will be some areas where it will be hard for residents to return to their homes for a long time," said Yukio Edano, the government's top government spokesman.

hundreds of former residents from Futaba and Okuma, the towns nearest the plant, were allowed to visit their homes – perhaps for the last time – to pick up belongings. Wearing masks and radiation suits, they drove through the 20km contaminated zone around the plant, where hundreds of animals have died and rotted in the sun, to find kitchens and living rooms partly reclaimed by nature.

It is the fate of people outside the evacuation zones, however, that causes the most bitter controversy. Parents in Fukushima City, 63km from the plant, have banded together to demand that the government do more to protect about 100,000 children. Schools have banned soccer and other outdoor sports. Windows are kept closed. "We've just been left to fend for ourselves," says Machiko Sato, a grandmother who lives in the city. "It makes me so angry."

Many parents have already sent their children to live with relatives or friends hundreds of kilometres away. Some want the government to evacuate the entire two million population of Fukushima Prefecture. "They're demanding the right to be able to evacuate," says anti-nuclear activist Aileen Mioko Smith, who works with the parents. "In other words, if they evacuate they want the government to support them."

Aid Fukushima: The UN's Office for the Co-ordination of Humanitarian Affairs reported bilateral aid worth $95m Chernobyl: 12 years after the disaster, the then Ukrainian president, Leonid Kuchma, complained that his country was still waiting for international help.

But many experts warn that the crisis is just beginning. Professor Tim Mousseau, a biological scientist who has spent more than a decade researching the genetic impact of radiation around Chernobyl, says he worries that many people in Fukushima are "burying their heads in the sand." His Chernobyl research concluded that biodiversity and the numbers of insects and spiders had shrunk inside the irradiated zone, and the bird population showed evidence of genetic defects, including smaller brain sizes.

"The truth is that we don't have sufficient data to provide accurate information on the long-term impact," he says. "What we can say, though, is that there are very likely to be very significant long-term health impact from prolonged exposure."

Economic cost Fukushima: Japan has estimated it will cost as much as £188bn to rebuild following the earthquake, tsunami and nuclear crisis. Chernobyl There are a number of estimates of the economic impact, but thetotal cost is thought to be about £144bn.

Safety Fukushima: workers are allowed to operate in the crippled plant up to a dose of 250mSv (millisieverts). Chernobyl: People exposed to 350mSv were relocated. In most countries the maximum annual dosage for a worker is 20mSv. The allowed dose for someone living close to a nuclear plant is 1mSv a year.

Death toll Fukushima: Two workers died inside the plant. Some scientists predict that one million lives will be lost to cancer. Chernobyl: It is difficult to say how many people died on the day of the disaster because of state security, but Greenpeace estimates that 200,000 have died from radiation-linked cancers in the 25 years since the accident.

Exclusion zone Fukushima: Tokyo initially ordered a 20km radius exclusion zone around the plant Chernobyl: The initial radius of the Chernobyl zone was set at 30km – 25 years later it is still largely in place.

Compensation Fukushima: Tepco's share price has collapsed since the disaster largely because of the amount it will need to pay out, about £10,000 a person Chernobyl: Not a lot. It has been reported that Armenian victims of the disaster were offered about £6 each in 1986

So far, at least, the authorities say that is not necessary. The official line is that the accident at the plant is winding down and radiation levels outside of the exclusion zone and designated "hot spots" are safe.

Japan has been slow to admit the scale of the meltdown. But now the truth is coming out. David McNeill reports from Soma City

Progress Energy powered down its reactors in Brunswick, North Carolina, and Dominion Resources cut production at one reactor at its Millstone plant in New London, Connecticut, by 70%. Another Dominion plant in Virginia, which had gone down because of last week's earthquake, remained offline for Irene.