The Fukushima nuclear meltdown continues unabated — Helen Caldicott, Independent Australia

Helen Caldicott sums up the situation here:

” Recent reporting of a huge radiation measurement at Unit 2 in the Fukushima Daichi reactor complex does not signify that there is a peak in radiation in the reactor building.

All that it indicates is that, for the first time, the Japanese have been able to measure the intense radiation given off by the molten fuel, as each previous attempt has led to failure because the radiation is so intense the robotic parts were functionally destroyed.

The radiation measurement was 530 sieverts, or 53,000 rems (Roentgen Equivalent for Man). The dose at which half an exposed population would die is 250 to 500 rems, so this is a massive measurement. It is quite likely had the robot been able to penetrate deeper into the inner cavern containing the molten corium, the measurement would have been much greater.

These facts illustrate why it will be almost impossible to “decommission” units 1, 2 and 3 as no human could ever be exposed to such extreme radiation. This fact means that Fukushima Daichi will remain a diabolical blot upon Japan and the world for the rest of time, sitting as it does on active earthquake zones.

What the photos taken by the robot did reveal was that some of the structural supports of Unit 2 have been damaged. It is also true that all four buildings were structurally damaged by the original earthquake some five years ago and by the subsequent hydrogen explosions so, should there be an earthquake greater than seven on the Richter scale, it is very possible that one or more of these structures could collapse, leading to a massive release of radiation as the building fell on the molten core beneath. But units 1, 2 and 3 also contain cooling pools with very radioactive fuel rods — numbering 392 in Unit 1, 615 in Unit 2, and 566 in Unit 3; if an earthquake were to breach a pool, the gamma rays would be so intense that the site would have to be permanently evacuated. The fuel from Unit 4 and its cooling pool has been removed.

But there is more to fear.

The reactor complex was built adjacent to a mountain range and millions of gallons of water emanate from the mountains daily beneath the reactor complex, causing some of the earth below the reactor buildings to partially liquefy. As the water flows beneath the damaged reactors, it immerses the three molten cores and becomes extremely radioactive as it continues its journey into the adjacent Pacific Ocean.

Every day since the accident began, 300 to 400 tons of water has poured into the Pacific where numerous isotopes – including cesium 137, 134, strontium 90, tritium, plutonium, americium and up to 100 more – enter the ocean and bio-concentrate by orders of magnitude at each step of the food chain — algae, crustaceans, little fish, big fish then us.

Fish swim thousands of miles and tuna, salmon and other species found on the American west coast now contain some of these radioactive elements, which are tasteless, odourless and invisible. Entering the human body by ingestion they concentrate in various organs, irradiating adjacent cells for many years. The cancer cycle is initiated by a single mutation in a single regulatory gene in a single cell and the incubation time for cancer is any time from 2 to 90 years. And no cancer defines its origin.

We could be catching radioactive fish in Australia or the fish that are imported could contain radioactive isotopes, but unless they are consistently tested we will never know.

As well as the mountain water reaching the Pacific Ocean, since the accident, TEPCO has daily pumped over 300 tons of sea water into the damaged reactors to keep them cool. It becomes intensely radioactive and is pumped out again and stored in over 1,200 huge storage tanks scattered over the Daichi site. These tanks could not withstand a large earthquake and could rupture releasing their contents into the ocean.

But even if that does not happen, TEPCO is rapidly running out of storage space and is trying to convince the local fishermen that it would be okay to empty the tanks into the sea. The Bremsstrahlung radiation like x-rays given off by these tanks is quite high – measuring 10 milirems – presenting a danger to the workers. There are over 4,000 workers on site each day, many recruited by the Yakuza (the Japanese Mafia) and include men who are homeless, drug addicts and those who are mentally unstable.

There’s another problem. Because the molten cores are continuously generating hydrogen, which is explosive, TEPCO has been pumping nitrogen into the reactors to dilute the hydrogen dangers.

Vast areas of Japan are now contaminated, including some areas of Tokyo, which are so radioactive that roadside soil measuring 7,000 becquerels (bc) per kilo would qualify to be buried in a radioactive waste facility in the U.S..

As previously explained, these radioactive elements concentrate in the food chain. The Fukushima Prefecture has always been a food bowl for Japan and, although much of the rice, vegetables and fruit now grown here is radioactive, there is a big push to sell this food both in the Japanese market and overseas. Taiwan has banned the sale of Japanese food, but Australia and the U.S. have not.

Prime Minister Abe recently passed a law that any reporter who told the truth about the situation could be [jail]ed for ten years. In addition, doctors who tell their patients their disease could be radiation related will not be paid, so there is an immense cover-up in Japan as well as the global media.

The Prefectural Oversite Committee for Fukushima Health is only looking at thyroid cancer among the population and by June 2016, 172 people who were under the age of 18 at the time of the accident have developed, or have suspected, thyroid cancer; the normal incidence in this population is 1 to 2 per million.

However, other cancers and leukemia that are caused by radiation are not being routinely documented, nor are congenital malformations, which were, and are, still rife among the exposed Chernobyl population.

Bottom line, these reactors will never be cleaned up nor decommissioned because such a task is not humanly possible. Hence, they will continue to pour water into the Pacific for the rest of time and threaten Japan and the northern hemisphere with massive releases of radiation should there be another large earthquake. ”

by Helen Caldicott


Fukushima radiation in the Pacific (revisited) — Triple Pundit

by RP Siegel

” My recent post on the spread of radiation stemming from the Fukushima nuclear accident drew quite a few questioning comments. Specifically the article suggested that radiation from the accident was drifting across the Pacific at levels high enough to cause alarm. It turns out such cause for alarm was exaggerated, though there is still reason to be concerned. I appreciate the feedback. I acknowledge that I relied on sources with which I was unfamiliar and posted some information that has been shown to be incorrect. I apologize.

To all who publish online, beware. Bad news travels fast. It gives credence to the old saying, “A lie can travel halfway around the world while the truth is still putting its pants on.” This is especially true on the Internet. I truly hope no one was harmed by this information. Now begins the task of earning back your trust which, though hard-earned, can be quickly lost.

I think the best way to start is to post a revised story on what is actually happening in the waters around Fukushima, Japan, as well as those farther afield.

Let’s start by addressing the points made in the original story.

For starters the initial source, PeakOil, used a bogus NOAA graphic to sensationalize the story, having carefully scrubbed out the legend showing that the colors actually represented wave heights at the peak of the tsunami, not radiation levels as the site would have you believe. I checked this image out, noticed this and chose not to use it in my post. Still, I continued to take the central thrust of the story as true.

Several people went to the generally reliable Snopes site to question the story and found confirmation of their suspicions. The blatant misuse of the NOAA chart is clearly called and tossed into the trash where it belongs. An interesting thing about the Snopes post, however, is that while the site prominently displays a text clipping stating that, “each day 300 tons of radioactive waste seeps into the ocean,” it never specifically addresses that claim.

I dug further and found that number actually comes from a quote by Yushi Yoneyama, an official with the Japanese Ministry of Economy, Trade and Industry, which oversees energy policy as quoted in Reuters (generally considered unassailable) and elsewhere. In 2013, Yoneyama said, “We think that the volume of water [leaking into the Pacific] is about 300 tonnes a day.” Of course, anyone could be wrong, but who am I to question Reuters or a Japanese government official? I don’t.

That’s not to say Japanese government officials, or officers of TEPCO, can always be counted on to tell the truth, but their interest has generally been to minimize the extent of the damage, not to embellish it.

As for that amount of leakage, that’s equivalent to about 90,000 gallons of radioactive water. That sounds like quite a bit. But compared to the volume of the Pacific Ocean, it’s not a lot at all. Still, when that much leaks out each day, over the course of a year, it adds up to 33 million gallons. And it’s been five years now.

Even today, TEPCO only acknowledges that radioactive water threatens to flood out of the plant and into the ocean. The company denied, until recently, that any water leaked from the plant at all, even when fish contaminated with high levels of radiation were found near the plant by independent researchers from the University of Tokyo, raising major concerns for local fishermen.

The story regarding radiation reaching the Canadian West Coast, which claimed levels of iodine-131 were 300 times background levels, was recently updated with an editor’s statement that the original figures were incorrect.

Reports of a wildlife biologist (Alexandra Morton) pulling hundreds of herring out of the waters off British Columbia with blood coming out of their eyes and gills have not been discredited. However, there is no evidence linking this observation directly to radiation from Fukushima or anywhere else.

The claim that radiation levels found in tuna off the Oregon coast had tripled also appears to be legitimate. However, those levels are still substantially below what would be considered a health threat.

Having sorted through that, I would summarize as follows: Contaminated water continues to enter to ocean from the Fukushima site in significant volume. Traces of radiation have been found in various locations around the Pacific. It also appears that the levels detected at this time do not indicate any immediate threat to humans outside of Japan. That being said, our knowledge of the long-term impacts of these types of radiation on the oceans, and on ourselves, is far from complete.

Upon review, most of the statements in the original piece were in fact true, but I acknowledge the overall sense was that of an exaggerated cause for concern. What this shows is how easily a group of facts taken out of context can become a convincing story — a lesson for all of us. Putting it on the Internet is like putting a match to a dry grassland.

What is far less clear is what the actual levels are and where they can be found. What makes writing about this issue so difficult, and even dangerous, is the combination of two things: It’s a frightening subject, and there is very little solid information being made available.

In my efforts to bring in some more solid facts, I reached out to Greenpeace, which is monitoring the situation carefully. The group sent me some additional information in a press release with links to reports published outside the U.S.

Greenpeace’s famed ship, the Rainbow Warrior, went out to sample the waters around Fukushima in February of this year with former Japanese Prime Minister Mr. Naoto Kan onboard. What they found was that radiation in the seabed off Fukushima “is hundreds of times above pre-2011 levels.” They also found levels in nearby rivers that were “up to 200 times higher than ocean sediment.”

Expressing concern, Ai Kashiwagi, energy campaigner for Greenpeace Japan, said: “These river samples were taken in areas where the Abe government is stating it is safe for people to live. But the results show there is no return to normal after this nuclear catastrophe.”

The areas sampled include the Niida River in Minami Soma, where readings measured as high as 29,800 becquerels per kilogram (Bq/kg) for radio-cesium. (For those new to the subject, a becquerel is a derived unit that measures radioactivity.) More samples taken at the estuary of the Abukuma River in Miyagi prefecture, more than 90 kilometers north of the Fukushima Daiichi plant, found levels in sediment as high as 6,500 Bq/kg. To put that in perspective, recorded levels in the seabed near the plant before the disaster were 0.65 Bq/kg.

Kendra Ulrich, senior global energy campaigner for Greenpeace Japan, explained: “The sheer size of the Pacific Ocean combined with powerful complex currents means the largest single release of radioactivity into the marine environment has led to the widespread dispersal of contamination.”

Greenpeace expressed concern that the order scheduled to allow people to return to these areas next March “cannot be permitted to stand.” The group claims that “these ecosystems cannot simply be decontaminated.”

Greenpeace’s report, which came out in July of this year, concludes by saying the impact of the accident will persist for “decades to centuries.”

So, while we have not yet seen the global-scale consequences some predicted, the situation is indeed bad and getting worse. TEPCO continues to build steel tanks at the rate of three per week, to house a great deal of contaminated groundwater while awaiting decontamination. But according to this PBS documentary, the company will run out of room for more tanks sometime next year. The gravity-fed water filtration system has been effective in removing most contaminants, except for tritium. Tritium is a relatively weak radionuclide with a half-life of 12.5 years, which means it will take about 100 years to fully break down.

The molten nuclear cores in reactors still remain in three reactors. And the site will not be fully stabilized until those are removed. But the radioactivity level in those reactors is far too high for people to enter. TEPCO plans to develop robots to go in and retrieve the molten fuel. The company says that retrieval is estimated to begin in 2020.

In closing, while the level of concern suggested in the prior piece was overstated, I maintain that the situation at Fukushima is far from resolved and that it remains a serious concern, particularly in Japan. I further maintain that any plans to continue expanding nuclear power must include an in-depth review of what has happened in Fukushima, with the understanding that this story is far from over. ”


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


Tritium Exposé — Fairewinds Energy Education

” Supporters of atomic power, who are not scientists, have been able to broadcast their opinions to the public with hellacious titles such as Lies, Damned Lies, and Statistics: Putting Indian Point Hysteria in Perspective by attorney and lobbyist Jerry Kremer for the Huffington Post. In an effort to combat misinformation and keep you informed, Fairewinds reached out to international radiation expert Dr. Ian Fairlie to clear up the false assurances and scientific denial spread by the nuclear industry and its chums.

Tritium, the radioactive isotope and bi-product of nuclear power generation, is making headlines with notable leaks at 75% of all the reactors in the United States, including Indian Point in New York, and Turkey Point in Florida. Speaking with renowned British scientist, Dr. Ian Fairlie, the Fairewinds Crew confirms the magnitude and true risk of tritium to the human body in its three various forms: tritiated water, tritiated air, and organically bound tritium.

Dr. Fairlie is an independent consultant on radioactivity in the environment. He has a degree in radiation biology from Bart’s Hospital in London and did his doctoral studies at Imperial College in London and Princeton University, concerning the radiological hazards of nuclear fuel reprocessing. Ian was formerly with the United Kingdom’s Department for Environment, Food, and Rural Affairs specializing in radiation risks from nuclear power stations. From 2000 to 2004, he was head of the Secretariat to the UK Government’s CERRIE Committee examining radiation risk of internal emitters. Since retiring from government service, he has acted as consultant to the European Parliament. ”

source with podcast and video

Is it safe to dump Fukushima waste into the sea? — The Guardian; Inquisitr

” More than 1,000 tanks brimming with irradiated water stand inland from the Fukushima nuclear plant. Each day 300 tonnes of water are pumped through Fukushima’s ruined reactors to keep them cool. As the water washes through the plant it collects a slew of radioactive particles.

The company that owns the plant – The Tokyo Electric Power Company (Tepco) – has deployed filtration devices that have stripped very dangerous isotopes of strontium and caesium from the flow.

But the water being stored in the tanks still contains tritium, an isotope of hydrogen with two neutrons. Tritium is a major by-product of nuclear reactions and is difficult and expensive to remove from water.

Now, Japan’s Nuclear Regulation Authority (NRA) has launched a campaign to convince a sceptical world that dumping up to 800,000 tonnes of contaminated water into the Pacific Ocean is a safe and responsible thing to do.

NRA chairman Shunichi Tanaka has officially called on Tepco to work towards a release. The International Atomic Energy Agency (IAEA) last year also issued a call for a release to be considered and for Tepco to perform an assessment of the potential impacts. For its part, Tepco has said there are no current plans to release the water. But the Associated Press (AP) reported that company officials are saying in private that they may have no choice.

According to Tanaka, Tritium is “so weak in its radioactivity it won’t penetrate plastic wrapping”. The substance can be harmful if ingested. According to AP, Tanaka had demonstrated the relatively tiny amount of tritium present in the combined Fukushima standing tanks – 57ml in total – by holding a small bottle half full of blue liquid in front of reporters.

A more useful measure of the amount of tritium is its radioactivity, which is measured in becquerels. According to the NRA, the tanks at Fukushima contain 3.4 peta becquerels (PBq) of tritium.

Despite the number of zeros in this measurement (there are 14), this is not a big number, said Ken Buesseler, a senior scientist at the Woods Hole Oceanographic Institution.

To put it in context, the natural global accumulation of tritium is a relatively tiny 2,200 PBq. The isotope has a half life of 12.3 years and is only created naturally on Earth by a rare reaction between cosmic rays and the atmosphere. By far the largest source of tritium in our environment is the nuclear weapons testing program of last century, which dumped a total of 186,000 PBq into the world’s oceans. Over time this has decayed to roughly 8,000 PBq. Another significant source of tritium are nuclear power stations, which have long dumped tritium-contaminated water into the ocean.

“I would think more has been put into the Irish Sea [from the UK’s Sellafield plant] than would ever be released off Japan,” said Buesseler. So far, the Fukushima disaster has seen 0.1-0.5 PBq leaked or released into the Pacific.

Even if all of the contaminated water were released into the ocean, it would not contain enough tritium to be detectable by the time it dispersed and reached the US west coast about four years later, said Simon Boxall, an oceanographer at the University of Southampton.

“In the broad scale of things, if they do end up putting the material in the Pacific, it will have minimal effect on an ocean basin scale,” said Boxall. “In an ideal world, we wouldn’t be in this situation. But the question is, what is the safest way forward? In many ways this is a pragmatic solution.”

But Boxall said there may be local effects – especially on the already heavily impacted fishing industry – as the contaminated water would take time to disperse.

International maritime law prohibits the building of a pipeline to send the waste offshore. Therefore any release would need to be slow. Tepco did not respond to questions regarding the environmental impact study called for by the IAEA.

Despite harbouring few prima facie fears about the 3.4PBq of tritium stored at Fukushima, Buesseler said the lack of transparency surrounding much of the post-tsunami decommissioning process made it impossible to be definitive about the safety of any course of action.

“Until you get the hard data, it’s hard to say if it’s a good idea or not. I want to have independent confirmation of what’s in every tank, which isotopes, how much they want to release per day. You get more of ‘don’t worry, trust us’,” said Buesseler

He notes that there have been minor differences between the official Tepco line that all leaks have stopped and Buesseler’s own measurements of very low levels of caesium and strontium still entering the ocean from the plant.

“It’s easy to have conspiracy theories when no-one is independently assessing what is going on,” he said.

The push for release will also be a blow to the hopes of US start-up Kurion, and their new parent company Veolia, which was awarded a $10m (£7m) grant from the Japanese government in 2014 to demonstrate that its tritium scrubbing technology could be scaled to meet the challenge of the Fukushima problem. The plan would create 90,000 tonnes of hydrogen gas, which Kurion said could be used to power vehicles.

Neither Tepco, nor Kurion, responded to requests for cost estimates of implementing this technology at the site. Kurion’s website calls it “cost-effective” and has said it could have its demonstration plant running within 18 months.

These costs are fundamental to the question of whether to release the material, because whatever they are, it is the price Japan seems unwilling to pay to fully clean up the lingering mess at Fukushima. ”

by Karl Mathiesen


* * *

Here’s another perspective on the dumping of tritiated water in the Pacific by Inquisitr.

Five years after the meltdown, is it safe to live near Fukushima? — Science

” A  long, grinding struggle back to normal is underway at the Fukushima Daiichi Nuclear Power Plant in Japan. As workers make progress in cleaning up contaminated land surrounding its infamous reactor, evacuees are grappling with whether to return to homes sealed off since the accident there 5 years ago. The power plant itself remains a dangerous disaster zone, with workers just beginning the complex, risky job of locating the melted fuel and figuring out how to remove it.

The magnitude 9.0 earthquake that struck northeastern Japan on 11 March 2011 and the 40-meter tsunami that followed left 15,893 dead and 2572 missing, destroyed 127,290 buildings, and damaged more than a million more. It also triggered the meltdowns at Fukushima and the evacuation of 150,000 people from within 20 kilometers of the nuclear plant as well as from areas beyond that were hard hit by fallout.

Now, the nuclear refugees face a dilemma: How much radiation in their former homes is safe? In a herculean effort, authorities have so far scooped up some 9 million cubic meters of contaminated soil and leaves and washed down buildings and roadways with the goal of reducing outdoor radiation exposure to 0.23 microsieverts per hour. Last September, the government began lifting evacuation orders for the seven municipalities wholly or partly within 20 kilometers of the plant. As the work progresses, authorities expect that 70% of the evacuees will be allowed to return home by spring 2017.

But evacuees are torn over safety and compensation issues. Many claim they are being compelled to go home, even though radiation exposure levels, they feel, are still too high. “There has been no education regarding radiation,” says Katsunobu Sakurai, the mayor of Minamisoma, where 14,000 people were evacuated after the accident. “It’s difficult for many people to make the decision to return without knowing what these radiation levels mean and what is safe,” he says. Some citizen groups are suing the national government and Tokyo Electric Power Company (TEPCO), the Fukushima plant’s owner, over plans to end compensation payments for those who choose not to return home. Highly contaminated areas close to the nuclear plant will remain off limits indefinitely.

Conditions at the plant are “really stable,” the plant manager, Akira Ono, recently told reporters. Radioactivity and heat from the nuclear fuel have fallen substantially in the past 5 years, he says. But cleanup is off to a slow start, hampered by sketchy knowledge of where the nuclear fuel is located. Last year managers agreed to a road map for decommissioning the site over the next 30 to 40 years that calls for removing melted nuclear fuel masses and demolishing the plant’s four reactor halls at a cost that could top $9 billion. TEPCO intends to start removing nuclear debris from the reactors in 2021.

Ono puts the decommissioning at “around 10%” complete. One big hurdle was cleared in December 2014, when crews removed the last of 1535 fuel rods stored in the Unit 4 spent fuel pool. At the time of the accident, some feared that cooling water had drained out of the pool and exposed the fuel to air, which might have led to overheating and melting. It hadn’t, but the fuel remained a threat.

The biggest challenge at present, Ono says, is contaminated water. Cooling water is continuously poured over the melted cores of units 1, 2, and 3 to keep the fuel from overheating and melting again. The water drains into building basements, where it mixes with groundwater. To reduce the amount of contaminated water seeping into the ocean, TEPCO collects and stores it in 10-meter-tall steel tanks. They now fill nearly every corner of the grounds, holding some 750,000 tons of water. The government is evaluating experimental techniques for cleansing the water of a key radioisotope, tritium. Ono says a solution is sorely needed before the plant runs out of room for more tanks.

TEPCO has found ways to divert groundwater from the site, cutting infiltration to about 150 tons per day. Now it’s about to freeze out the rest. Borrowing a technique for making temporary subsurface barriers during tunnel construction, a contractor has driven 1500 pipes 30 meters down to bedrock, creating something akin to an underground picket fence encircling the four crippled reactor units. Brine chilled to –30°C circulating in the pipes will freeze the soil between the pipes; the frozen wall should keep groundwater out and contaminated water in. TEPCO was planning to start the operation shortly after Science went to press.

The most daunting task is recovering the fuel debris. TEPCO modeling and analyses suggest that most, if not all, of the fuel in the Unit 1 reactor melted, burned through the reactor pressure vessel, dropped to the bottom of the containment vessel, and perhaps ate into the concrete base. Units 2 and 3 suffered partial meltdowns, and some fuel may remain in the cores.

To try to confirm the location and condition of the melted fuel, the International Research Institute for Nuclear Decommissioning, set up by TEPCO and other entities, has been probing the reactors’ innards with muons. Wispy cousins of the electron, muons are generated by the trillions each minute when cosmic rays slam into the upper atmosphere. A few muons are absorbed or scattered, at a rate that depends on a material’s density. Because uranium is denser than steel or concrete, muon imaging can potentially locate the fuel debris.

In February 2015, a group at Japan’s High Energy Accelerator Research Organization in Tsukuba supplied two van-sized muon detectors, which TEPCO placed adjacent to the Unit 1 reactor at ground level. After a month of collecting muons, the detectors confirmed there was no fuel left in the core. Because they were positioned at ground level, the devices could not image the reactor building basements and so could not pin down where the fuel is or its condition. TEPCO plans to use robots to map the location of the fuel debris so it can develop a strategy for removing it (see story, right).

A second team has developed detectors that observe muons before and after they pass through an object of interest, promising a more precise picture of reactor interiors. For Fukushima, the researchers—from Los Alamos National Laboratory in New Mexico and Japan’s Toshiba Corp.—built mammoth detectors, 7 meters across, which they intended to place outside Unit 2. That work has been postponed because TEPCO decided to first send a robot into the containment vessel; high radiation levels have delayed that plan. “Our current task is to reduce that exposure,” Ono says, using robotic floor and wall scrubbers in the area workers need to access to deploy the robot.

While the authorities struggle to clean up the site and resettle residents, some locals are judging safety for themselves. In 2014, a group of enterprising high school students in Fukushima city, outside the evacuation zone, launched an international radiation-dosimetry project. Some 216 students and teachers at six schools in Fukushima Prefecture, six elsewhere in Japan, four in France, eight in Poland, and two in Belarus wore dosimeters for 2 weeks while keeping detailed diaries of their whereabouts and activities. “I wanted to know how high my exposure dose was and I wanted to compare that dose with people living in other places,” explains Haruka Onodera, a member of Fukushima High School’s Super Science Club, which conceived the project. The students published their findings last November in the Journal of Radiological Protection. Their conclusion: “High school students in Fukushima [Prefecture] do not suffer from significantly higher levels of radiation” than those living elsewhere, Onodera says.

That’s good news for Fukushima city residents, perhaps, but cold comfort to displaced people now weighing the prospect of moving back to homes closer to the shattered nuclear plant. ”

by Dennis Normile