Dangerous radioactive hot particles span the globe — Beyond Nuclear International

” When reactors exploded and melted down at the Fukushima nuclear power complex in March 2011, they launched radioactivity from their ruined cores into the unprotected environment. Some of this toxic radioactivity was in the form of hot particles (radioactive microparticles) that congealed and became airborne by attaching to dusts and traveling great distances.

However, the Fukushima disaster is only the most recent example of atomic power and nuclear weapons sites creating and spreading these microparticles. Prior occurrences include various U.S. weapons sites and the ruined Chernobyl reactor. While government and industry cover up this hazard, community volunteer citizen science efforts – collaborations between scientists and community volunteers – are tracking the problem to raise awareness of its tremendous danger in Japan and across the globe.

After the Fukushima nuclear disaster began, one highly radioactive specimen, a particle small enough to inhale or ingest, was found in a private home where it should not have been, hundreds of miles from its source, in a vacuum cleaner bag containing simple house dust.

This “high activity radioactively-hot dust particle” came from a house in Nagoya, Japan – after it had traveled 270 miles from Fukushima. The only radioactive particle found in the home’s vacuum cleaner bag, it was an unimaginably minuscule part of the ruined radioactive core material from Fukushima – many times smaller than the width of a human hair. We know it came from Fukushima because it contained cesium-134, meaning that the particle came from a recent release, and we know it is a piece of core material specifically because it was so radioactive that it could not have come from any other material.

Most of the particle’s radioactivity came from cesium-134 and cesium-137. By the time it was collected, some of the particle’s radioactivity, mostly from iodine-131, had already decayed. Named “corium” by scientists, it was still thousands of times more radioactive (5,200,000,000,000,000 disintegrations per second per kilogram — that’s 5.2 quadrillion more than the average activity (26,000 disintegrations per second per kilogram) found in dust and soil samples collected through community volunteer efforts from across Japan — with a focus on areas around Fukushima — since the 2011 nuclear disaster began. By way of comparison, in the U.S., average soil and dust activity is thousands of times lower.

Due to privacy concerns, we are not permitted to know the identities of the Nagoya residents who participated in the dust sampling collection and in whose home the particle was found. Nor do we know how many people lived in the home; if there were children or babies present; or pets; or pregnant women. And we will never know if there were any other radioactive microparticles in the home that did not make it into that vacuum cleaner bag.

We do not know how the particle got there. No one in the home (nor the vacuum cleaner) had any connection to the Fukushima reactors or the exclusion zone. Was the particle transported by a car tire into their city? On someone’s shoes? Did it fly in through a window after being lofted by air currents? Did it arrive by a combination of forces? We do not know if other particles like this travelled just as far in all directions, or who may have taken a breath at just the wrong moment, so that a similar microparticle might be lodged in their lungs.

We do know the residents in Nagoya were notified about the particle’s presence, and that if it had been inhaled or ingested, it could have proven lethal over time. This corium particle would have destroyed tissue near it, potentially threatening the function of any organ that tissue was part of. But the particle’s additional danger would come from what it didn’t destroy – that is tissue that is damaged but survives and can go on to mutate into cancer or non-cancer diseases.

We also know that had scientists and citizens not worked together to collect samples, we would never have known a microparticle of corium existed at all at a distance so far away from the Fukushima meltdowns. If the presence of this particle – and its potential for inhalation – had gone unnoticed, any calculations of the doses to residents of this home would have been significantly underestimated. And while the Nagoya particle may simply be an outlier, it shows how inaccurate radiation risk assessment has turned out to be. All of these microparticles, even ones less radioactive, may pose significant health risks inside the body that are currently uncalculated.

Citizen and scientists collaborations show us that radioactive microparticles are a worldwide problem. Yet action by public health advocates and government officials has been slow to nonexistent in recognizing this danger, much less working to protect people against exposure from it. Detecting radioactive microparticles is extremely difficult, in part because detecting them and proving their danger requires specialized techniques and equipment. But this is no excuse for governments to ignore the problem altogether as they continue to do. When experts tell us what our risks are from radiation exposure, risks from these microparticles remain unaccounted for in every country in the world. Speculation swirls around these particles and whether the rapid-onset cancers occurring in Japan are possibly due to their presence.

Radioactive particles across the globe

Collections of various samples (home air filters, vehicle engine intake filters, soils, samples of dust from vacuum cleaner bags) have revealed radioactive microparticles from Fukushima made it as far as Seattle, WA and Portland, OR in the U.S.,and to the Western coast of Canada.

Not surprisingly, microparticles in Japan were much more radioactive than those that made their way to the U.S. and contained more varied radioisotopes, thus posing a much greater health risk. In the case of some filters in Japan, contamination was high enough to be classified as “radioactive waste.”

In addition to catastrophic releases from nuclear power facilities, these particles come from atomic detonations, other nuclear industry processes such as mining and atomic fuel fabrication, and nuclear facility releases of radioactivity, as well as leaking atomic waste dumps. Nuclear workers, First Nations Tribes, and local residents have submitted samples for testing around such facilities. Particles have been detected in the environment and in house dusts in communities around weapons facilities in Los Alamos, NM; Hanford, WA; and Rocky Flats, CO. Thorium, plutonium, and uranium from nuclear facilities were found “outside of radiation protection zones,” including workplaces, workers’ homes and cars. “Given the small respirable size of these radioactive microparticles, they are a potential source of internal exposure from inhalation or ingestion,” according to Dr. Marco Kaltofen of Worcester Polytechnic Institute.

In some cases, radioactive particle releases can be higher from nuclear power catastrophes than disasters at atomic bomb facilities. In 1986, Chernobyl also released radioactive particles that still contaminate the environment today. Forest fires are spreading them further. Current community volunteer citizen science efforts are underway in the environs of the Santa Susana Field Laboratory (SSFL) – a former reactor test site adjacent to Simi Valley, CA – and the site of several unanticipated and unmonitored nuclear releases, a meltdown, and the November 2018 Woolsey forest fire.

Similar work is being carried out in Pike County, OH, host to a uranium enrichment facility for military and civilian nuclear reactors that has spread radioactive contamination to a nearby middle school, the grounds of which have now been quarantined. The U.S. Department of Energy hid the school contamination for two years, prompting public outrage and calls for health investigations into the high incidence of local childhood disease.

Ignoring danger to human health, environment

The U.S. Nuclear Regulatory Commission (NRC) currently has an existing 10-mile emergency planning radius around commercial nuclear power reactors, a zone the NRC does not place around other nuclear facilities. This 10-mile zone is not large enough to account for exposures that often occur well outside of it.

While the NRC is aware of the radioactive microparticle threat, its dose models fail to provide the extensive, detailed calculations required to actually protect anyone working at or living near these sites. Since radioactive microparticles remain a threat for generations after a catastrophe begins, the NRC should account for continuing exposure to communities and their people for the decades or centuries it takes for such materials to be safe for human or animal exposure. ”

by Cindy Folkers, Beyond Nuclear International; with technical and editorial input from Arnie and Maggie Gundersen

source with photos

Fukushima’a other big problem: A Million tons of radioactive water — Wired

” The tsunami-driven seawater that engulfed Japan’s Fukushima Daiichi nuclear plant has long since receded. But plant officials are still struggling to cope with another dangerous flood: the enormous amounts of radioactive water the crippled facility generates each day. More than 1 million tons of radiation-laced water is already being kept on-site in an ever-expanding forest of hundreds of hulking steel tanks—and so far, there’s no plan to deal with them.

The earthquake and tsunami that hammered Fukushima on March 11, 2011 triggered meltdowns in three of its six reactors. That left messes of intensely radioactive fuel somewhere loose in the reactor buildings—though no one knows exactly where. What is known, however, is that every day, as much as much as 150 tons of groundwater percolates into the reactors through cracks in their foundations, becoming contaminated with radioactive isotopes in the process.

To keep that water from leaking into the ground or the Pacific, Tepco, the giant utility that owns the plant, pumps it out and runs it through a massive filtering system housed in a building the size of a small aircraft hangar. Inside are arrays of seven-foot tall stainless steel tubes, filled with sand grain-like particles that perform a process called ion exchange. The particles grab on to ions of cesium, strontium, and other dangerous isotopes in the water, making room for them by spitting out sodium. The highly toxic sludge created as a byproduct is stored elsewhere on the site in thousands of sealed canisters.

This technology has improved since the catastrophe. The first filtering systems, installed just weeks after the disaster by California-based Kurion Inc. (which has since been bought by Veolia, a French resource management company), only caught cesium, a strong gamma radiation emitter that makes it the most dangerous of the isotopes in the water. The tubes in those arrays were filled with highly modified grains of naturally occurring volcanic minerals called zeolites. By 2013, the company developed entirely artificial particles—a form of titano silicate—that also grab strontium.

The filters, however, don’t catch tritium, a radioactive isotope of hydrogen. That’s a much trickier task. Cesium and strontium atoms go into solution with the water, like sugar in tea; but tritium can bond with oxygen just like regular hydrogen, rendering the water molecules themselves radioactive. “It’s one thing to separate cesium from water, but how do you separate water from water?” asks John Raymont, Kurion’s founder and now president of Veolia’s nuclear solutions group. The company claims to have developed a system that can do the job, but Tepco has so far balked at the multi-billion dollar cost.

So for now, the tritiated water is pumped into a steadily growing collection of tanks. There are already hundreds of them, and Tepco has to start building a new one every four days.

Tepco has at least reduced the water’s inflow. As much as 400 tons per day was gushing in just a couple of years ago. In an effort to keep the groundwater from getting in, Tepco has built a network of pumps, and in 2016 installed an underground “ice wall”—a $300 million subterranean fence of 30-yard-long rods through which tons of sub-zero brine is pumped, freezing the surrounding earth. All of which helps, but hasn’t solved the problem.

Tritium is far less dangerous than cesium—it emits a weaker, lower-energy form of radiation. Still, all that tritiated water can’t just be stored indefinitely. “Some of those tanks and pipes will eventually fail. It’s inevitable,” says Dale Klein, a former head of the US Nuclear Regulatory Commission who has been consulting with Tepco since the early days following the disaster. (In fact, hundreds of tons of water leaked out of the tanks in 2013 and 2014, sparking an international outcry. Tepco has since improved their design.)

Klein, among others, believes that the concentrations of tritium are low enough that the water can safely be released into the sea. “They should dilute and dispose of it,” he says. “It would be better to have a controlled release than an accidental one.”

But the notion of dumping tons of radioactive water into the ocean is understandably a tough sell. Whatever faith the Japanese public had left in Tepco took a further beating in the first couple of years after the meltdowns, when several investigations forced the company to acknowledge they had underreported the amount of radiation released during and after the disaster. Japan’s fishing industry raises a ruckus whenever the idea of dumping the tritiated water is broached; they already have to contend with import restrictions imposed by neighboring countries worried about eating contaminated fish. Japan’s neighbors including China, Korea, and Taiwan have also objected.

For now, all Tepco can do is keep building tanks, and hope that someone comes up with a solution before they run out of room—or the next earthquake hits. “

by Vince Beiser, Wired

source with internal links and photo

Move over Chernobyl, Fukushima is now officially the worst nuclear power disaster in history — CounterPunch

” The radiation dispersed into the environment by the three reactor meltdowns at Fukushima-Daiichi in Japan has exceeded that of the April 26, 1986 Chernobyl catastrophe, so we may stop calling it the “second worst” nuclear power disaster in history. Total atmospheric releases from Fukushima are estimated to be between 5.6 and 8.1 times that of Chernobyl, according to the 2013 World Nuclear Industry Status Report. Professor Komei Hosokawa, who wrote the report’s Fukushima section, told London’s Channel 4 News then, “Almost every day new things happen, and there is no sign that they will control the situation in the next few months or years.”

Tokyo Electric Power Co. has estimated that about 900 peta-becquerels have spewed from Fukushima, and the updated 2016 TORCH Report estimates that Chernobyl dispersed 110 peta-becquerels. (A Becquerel is one atomic disintegration per second. The “peta-becquerel” is a quadrillion, or a thousand trillion Becquerels.)

Chernobyl’s reactor No. 4 in Ukraine suffered several explosions, blew apart and burned for 40 days, sending clouds of radioactive materials high into the atmosphere, and spreading fallout across the whole of the Northern Hemisphere — depositing cesium-137 in Minnesota’s milk.

The likelihood of similar or worse reactor disasters was estimated by James Asselstine of the Nuclear Regulatory Commission (NRC), who testified to Congress in 1986: “We can expect to see a core meltdown accident within the next 20 years, and it … could result in off-site releases of radiation … as large as or larger than the releases … at Chernobyl. Fukushima-Daiichi came 25 years later.

Contamination of soil, vegetation and water is so widespread in Japan that evacuating all the at-risk populations could collapse the economy, much as Chernobyl did to the former Soviet Union. For this reason, the Japanese government standard for decontaminating soil there is far less stringent than the standard used in Ukraine after Chernobyl.

Fukushima’s Cesium-137 Release Tops Chernobyl’s

The Korea Atomic Energy Research (KAER) Institute outside of Seoul reported in July 2014 that Fukushima-Daiichi’s three reactor meltdowns may have emitted two to four times as much cesium-137 as the reactor catastrophe at Chernobyl.

To determine its estimate of the cesium-137 that was released into the environment from Fukushima, the Cesium-137 release fraction (4% to the atmosphere, 16% to the ocean) was multiplied by the cesium-137 inventory in the uranium fuel inside the three melted reactors (760 to 820 quadrillion Becquerel, or Bq), with these results:

Ocean release of cesium-137 from Fukushima (the worst ever recorded): 121.6 to 131.2 quadrillion Becquerel (16% x 760 to 820 quadrillion Bq). Atmospheric release of Cesium-137 from Fukushima: 30.4 to 32.8 quadrillion Becquerel (4% x 760 to 820 quadrillion Bq).

Total release of Cesium-137 to the environment from Fukushima: 152 to 164 quadrillion Becquerel. Total release of Cesium-137 into the environment from Chernobyl: between 70 and 110 quadrillion Bq.

The Fukushima-Daiichi reactors’ estimated inventory of 760 to 820 quadrillion Bq (petabecquerels) of Cesium-137 used by the KAER Institute is significantly lower than the US Department of Energy’s estimate of 1,300 quadrillion Bq. It is possible the Korean institute’s estimates of radioactive releases are low.

In Chernobyl, 30 years after its explosions and fire, what the Wall St. Journal last year called “the $2.45 billion shelter implementation plan” was finally completed in November 2016. A huge metal cover was moved into place over the wreckage of the reactor and its crumbling, hastily erected cement tomb. The giant new cover is 350 feet high, and engineers say it should last 100 years — far short of the 250,000-year radiation hazard underneath.

The first cover was going to work for a century too, but by 1996 was riddled with cracks and in danger of collapsing. Designers went to work then engineering a cover-for-the-cover, and after 20 years of work, the smoking radioactive waste monstrosity of Chernobyl has a new “tin chapeau.” But with extreme weather, tornadoes, earth tremors, corrosion and radiation-induced embrittlement it could need replacing about 2,500 times. ”

by John LaForge, CounterPunch

source with article sources listed at the bottom of the page

Local servicemen may have radiation poisoning from Fukushima — San Diego City Beat

” With a class action lawsuit pending, hundreds of Navy sailors say they can’t get the help they need.

“Right now, I know I have problems, but I’m afraid of actually finding out how bad they really are,” said William Zeller, a 33-year-old active-duty Navy servicemember living in San Diego. He’s one of the 4,500 sailors who were aboard the USS Ronald Reagan during Operation Tomodachi, a humanitarian aid mission sent to Japan the day after a tsunami triggered the 2011 Fukushima Daiichi nuclear meltdown.

“I know there’s something wrong,” Zeller said. “I’ve got many other people around me telling me I don’t look good, and I need to get checked out. While I am a workaholic, it’s a distraction.”

Zeller is only one of 318 sailors (and counting) who have joined a billion-dollar class action lawsuit filed in 2012 against the nuclear generators’ operating company, Tokyo Electric Power Company, or TEPCO, for injuries allegedly caused by radiation exposure.

The lawsuit argues TEPCO is financially responsible for the sailors’ medical care because the operating company, admittedly, did not inform the Japanese government of the meltdown. In turn, the Japanese government unknowingly misinformed the U.S. Navy of potential dangers of anchoring off the coast of Japan where the ship was engulfed in a plume of radiation for several hours.

“Everywhere we went we had to carry [gas masks] on our hips,” Zeller said. “We were turning on news networks, and we could see how we were right in the plume. You could taste the metallic air.”

In the six years since Fukushima, Zeller has only sought medical attention from the Navy since the care is financially covered.

“The military health system is a process, putting it politely,” he said, explaining how it took four years to learn he had abnormal bone growth, nerve damage and what he believes is irritable bowel syndrome, all of which began a year after Operation Tomodachi. His weight fluctuates 20 to 30 pounds within a month, and he’s unendingly fatigued.

“Before I went [on the USS Ronald Reagan], I used to be a martial arts instructor,” he said. “I used to go on regular bike rides. I hiked. I was in very good shape. Now, I wear a breathing machine when I go to sleep because I have respiratory problems. I literally just go to work and go home now. I don’t have the energy or the pain threshold to deal with anything else.”

Considering the Veterans Association’s inability to treat members in a timely or efficient manner, Zeller’s lawyer, Paul Garner, said VA care is not an option. Instead, they’re hopeful that a fund set up by former Japanese Prime Minister Junichiro Koizumi will come to fruition.

Koizumi announced the creation of the fund while visiting 10 affected sailors, including Zeller, in San Diego in May. Koizumi said he expects to raise $2 million by a March 31 cutoff date. The plan is to then transfer the money to the U.S. to supplement the sailor’s medical bills at, according to Garner, some of the best care centers across the country.

However, Garner knows $2 million won’t be enough to cover every need, especially since some sailors have reported symptoms appearing in their children who were born after Operation Tomodachi.

“I have no idea if it’s caused by the radiation that I was exposed to on the Reagan, but I don’t know that it’s not,” said Jason F., who was also on board the USS Ronald Reagan but didn’t want to share his last name while he’s still active duty. His breathing is audible over the phone, as if climbing several sets of stairs, but he’s tucking his three-year-old daughter into bed at their San Diego home.

“That’s standard breathing for me,” he said. “I don’t know what to do about it. She has difficulty breathing too,” he said of his daughter, who was born in 2013. “She snores like a grown man.”

Jason is 36 years old, in shape, never smoked a day in his life and didn’t have trouble breathing until after his time on the USS Ronald Reagan. His respiratory difficulties have aggrandized since 2011, peaking during a 2016 deployment where the doctors told him the contrasting temperatures were to blame and gave him an inhaler to puff on. It took a formal request to fly him off the ship to receive medical treatment in Bahrain, where he was told he had a 60 percent chance of tuberculosis and a 40 percent chance of lung cancer. He has since been diagnosed with asthma by an outside specialist, although the treatments aren’t working.

“It’s difficult for them to figure out,” Jason said. “I mean, how many patients have they had that are exposed to radiation? And are they trained for that?”

When Zeller mentioned radiation exposure to doctors at the Navy, he said he was told it was interesting, if acknowledged at all.

Lung cancer is one of several cancers associated with high radiation exposure, according to the U.S. Nuclear Regulatory Commission website, as well as leukemia, which several sailors have been diagnosed with. Bloody noses, rectal and gynecological bleeding, weakness and ulcers, are also symptoms reported by the sailors and are signs of radiation poisoning, according to the Scripps Health website.

In 2014, the Department of Defense published a report acknowledging that radiation exposure can cause such medical issues, but that the exposure levels were too low and the symptoms appeared too soon to make a connection.

While Zeller and Jason hope for financial support either from Koizumi’s fund or by winning the lawsuit, they want support for the others affected.

“I’m experiencing symptoms, but it’s not just for me,” Zeller said. “It’s for the individuals who are way worse than me and to bring attention to them… They have tumors, cancers, birth defects in their children, some individuals have mass muscle fatigue where their entire half of their body isn’t functional anymore, and they are stuck in wheelchairs. I am currently on the better end.”

The sailors are waiting for a decision from the 9th Circuit Court of Appeals determining whether the lawsuit will continue in the United States or in Japan, if at all.

In January, TEPCO urged the court to dismiss the case, citing that it is a political matter that could impact international relations.

Jason said the lawsuit is about more than money, specifically when it comes to his daughter’s future.

“I just want accountability,” he said. “I want her taken care of. Whatever that takes.” ”

by Torrey Bailey

source

Treated Fukushima water safe for release, Tepco adviser says — Bloomberg

” Treated water from Tokyo Electric Power Co. Holdings Inc.’s wrecked Fukushima nuclear plant north of Tokyo is safe to be released under controlled circumstances into the nearby Pacific Ocean, an independent adviser to the utility said.

“It is much better to do a controlled release in my view than to have an accidental release,” Dale Klein, the adviser and a former chairman of the U.S. Nuclear Regulatory Commission, said in an interview in Tokyo. “I get nervous about just storing all that water when you have about a thousand tanks. You have all the piping, all the valves, everything that can break. ”

More than five years after the meltdowns at Fukushima, Tokyo-based Tepco continues to struggle to contain the radiation-contaminated water that inundates the plant.

About 300 metric tons of water — partly from the nearby hills — flow into Fukushima’s reactor building daily, mixing with melted fuel and becoming tainted, according to the company’s website. For perspective, that’s roughly the amount of water contained in one lane of an Olympic-sized swimming pool.

The water is currently pumped out of the buildings and purified, lowering its radioactive content with a system called Advanced Liquid Processing System, or ALPS. The treated water, which still contains a radioactive element known as tritium, is then stored in one of roughly 1,000 tanks at the site.

Water Challenges

What to do with the treated water remains a headache for Tepco. The utility was urged by the International Atomic Energy Agency in May 2015 to consider discharging the water into the ocean. In early 2014, Klein, the Tepco adviser, criticized the company’s progress in managing the water situation, saying at the time that the task distracted Tepco from other important challenges associated with the cleanup.

Tepco will cooperate with the government, local authorities, and fishermen regarding what to do with the tritium water, spokesman Tatsuhiro Yamagishi said by phone. As of July 28, Tepco stored 668,352 tons of treated water at the Fukushima plant, while 188,462 tons of untreated water was waiting in a second set of tanks to be processed by ALPS, according to Tepco’s Yamagishi.

The government agency overseeing handling of the treated water hasn’t decided whether to go ahead with an ocean release because it needs to “weigh any potential impact on society,” according to an official who asked to not be named, citing internal policy.

“I hope the government will help move towards a decision,” Klein said.

Nuclear power plants routinely and safely release dilute concentrations of tritiated water, according to the the U.S. Nuclear Regulatory Commission.

Release of the “water will not be a safety issue, but it will be an emotional issue,” Klein said. “A lot of people are not going to know what tritium is and they’re just going to perceive that the water is glowing in the dark.” ”

by Stephen Stapczynski

source

Fukushima clean-up chief still hunting for 600 tonnes of melted radioactive fuel — Mark Willacy, ABC

” The operator of the stricken Fukushima nuclear plant has revealed that 600 tonnes of reactor fuel melted during the disaster, and that the exact location of the highly radioactive blobs remains a mystery.

 In an exclusive interview with Foreign Correspondent, the Tokyo Electric Power Company’s chief of decommissioning at Fukushima, Naohiro Masuda, said the company hoped to pinpoint the position of the fuel and begin removing it from 2021.

But he admitted the technology needed to remove the fuel has to be invented.

“Once we can find out the condition of the melted fuel and identify its location, I believe we can develop the necessary tools to retrieve it,” Mr Masuda said.

“So it’s important to find it as soon as possible.”

Clean-up to take decades, cost tens of billions of dollars

Reactors 1, 2 and 3 at the Fukushima Dai-ichi nuclear plant suffered catastrophic meltdowns in the hours and days after a giant tsunami swamped the facility on 11 March, 2011.

Thousands of workers are braving elevated radiation levels to stabilise and decommission the plant.

TEPCO says the process will take 30 to 40 years and tens of billions of dollars.

“In Reactor 1, all of the fuel has melted down from inside the pressure vessel,” Mr Masuda said.

“In reactors 2 and 3, about 30 per cent to 50 per cent remains in the pressure vessel and the rest has melted down. But unfortunately, we don’t know exactly where [the fuel] is.”

The head of the United States Nuclear Regulatory Commission (NRC) at the time of the meltdowns at Fukushima doubts the fuel can be retrieved, saying such an operation has never been done before.

“Nobody really knows where the fuel is at this point and this fuel is still very radioactive and will be for a long time,” said Gregory Jaczko in an interview with Foreign Correspondent in Washington.

“It may be possible that we’re never able to remove the fuel. You may just have to wind up leaving it there and somehow entomb it as it is.”

Radiation killing search robots inside reactor

For the first time, TEPCO has revealed just how much of the mostly uranium fuel melted down after the tsunami swamped the plant.

“It’s estimated that approximately 200 tonnes of debris lies within each unit,” said TEPCO’s Naohiro Masuda.

“So in total, about 600 tonnes of melted debris fuel and a mixture of concrete and other metals are likely to be there.”

TEPCO has attempted to use custom-built robots to access high-dose radiation parts of the reactor buildings where humans cannot go.

“All the robots have been disabled, the instrumentation, the camera … have been disabled because of the high radiation fields,” former NRC boss Gregory Jaczko said.

Appointed to head the US nuclear watchdog by President Barack Obama in 2009, Dr Jaczko resigned a year after the Fukushima disaster.

A particle physicist, he now questions the safety of nuclear power.

“You have to now accept that in all nuclear power plants, wherever they are in the world … that you can have this kind of a very catastrophic accident and you can release a significant amount of radiation and have a decade long clean-up effort on your hands,” he said.

10 million bags of contaminated soil in gigantic waste dumps

Another supporter turned opponent of nuclear power is Naoto Kan, who was the Japanese prime minister at the time of the Fukushima meltdowns.

He says those who argue that nuclear power is a safe, cheap source of energy are misguided.

“So far, the government is paying $70 billion to support TEPCO,” Mr Kan said.

“But that is not enough. It will probably cost more than $240 billion. I think 40 years [to decommission the plant] is an optimistic view.”

More than 100,000 Japanese are still unable to return home because their communities lie in elevated radiation zones.

Some people have returned to their towns and villages since the completion of decontamination work, which often involves the removal of up to 15 centimetres of topsoil from fields and from around homes.

More than 10 million large bags of contaminated soil and waste have so far been collected. The bags are now stored in thousands of sites around Fukushima, with some of the piles several storeys high.

“In order for people to come back, we need to show that the Fukushima plant is in a stable condition,” Naohiro Masuda said.

“We need to make that the situation … we’re working on something [for] which there is no textbook.” ”

by Mark Willacy

source