TEPCO to decommission 1 reactor at Fukushima No. 2 plant, mulling fate of 3 others

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Tokyo Electric Power Company Holdings Inc. (TEPCO) has informally decided to decommission the No. 1 reactor at its Fukushima No. 2 Nuclear Power Plant, it has been learned.

In the wake of the March 2011 Great East Japan Earthquake and tsunami and ensuing meltdowns at the Fukushima No. 1 plant in Fukushima Prefecture, local bodies and residents of the area who suffered extensive damage requested that all four reactors at the No. 2 plant also be decommissioned.

TEPCO had avoided stating a clear position on the No. 2 plant’s reactors, but there had been pressure from the government and ruling coalition for it to make a decision. The company accordingly decided to decommission the plant’s No. 1 reactor, which suffered the most damage, and will consider what to do with the other three reactors in the future.

The No. 1 reactor of the Fukushima No. 2 plant began operating in 1982. It was flooded by tsunami on March 11, 2011, and all four reactors at the plant remain idled. The No. 2 plant suffered less damage than the No. 1 plant, and if it passed screening by the Nuclear Regulation Authority, its reactors could be restarted. But the Fukushima Prefectural Government and all 59 local assemblies have asked TEPCO and the government to decommission all reactors in the prefecture.

TEPCO has remained busy handling compensation claims relating to the Fukushima nuclear disaster and the disaster cleanup. If it were to decommission all of the No. 2 plant’s reactors, they would lose value and it would have to write down huge losses. Company president Naomi Hirose has therefore avoided taking a clear position on the issue, saying, “I would like to consider it and make a decision as a business operator.”

Last year, however, officials decided to create a fund to cover the huge cost of handling the nuclear disaster, which is expected to reach 21.5 trillion yen, nearly double the original prediction. There was accordingly pressure from the government for TEPCO to reach an early decision on the fate of the No. 2 plant’s reactors.

The No. 1 reactor at the No. 2 plant is the oldest of the plant’s four reactors. It temporarily lost its cooling functions in the March 2011 disaster, and suffered the most damage among the four reactors. TEPCO believes that by limiting decommissioning to one reactor for the time being, it will be able to hold the decommissioning cost below 100 billion yen, minimizing the impact on company finances and on decommissioning work at the Fukushima No. 1 plant. However, a decision to decommission only one reactor at the No. 2 plant is unlikely to win public approval.

http://mainichi.jp/english/articles/20170317/p2a/00m/0na/024000c

Radiation Spikes At Fukushima

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Juan Carlos Lentijo of the International Atomic Energy Agency looks at tanks holding contaminated water and the Unit 4 and Unit 3 reactor buildings during a February 2015 tour of the tsunami-stricken Fukushima Daiichi nuclear power plant.

Almost six years after a tsunami caused a meltdown at the Fukushima Daiichi Nuclear Power Plant, the facility’s operator, Tokyo Electric Power (Tepco) faces overwhelming problems to clean up the site. Tepco now reports radiation in reactor 2 that would kill a worker in thirty seconds, and even destroys robots. Arjun Makhijani, the President of the Institute for Energy and Environmental Research and host Steve Curwood discuss the implications of this new report and the challenges of cleanup.

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Arjun Makhijani is the President of the Institute for Energy and Environmental Research.

Transcript

CURWOOD: It’s Living on Earth, I’m Steve Curwood.

Six years after an earthquake and resulting tsunami devastated Fukushima, Japan and led to the meltdown of three nuclear power reactors there on the coast, radiation levels have reached a staggering 530 sieverts an hour, many times higher than any previous reading. Tepco, the plant’s operator, claims that radiation is not leaking outside reactor number two, site of these readings, but concedes there’s a hole in the grating beneath the vessel that contains melted radioactive fuel.

Joining us now to explain what it all means is Arjun Makhijani, President of the Institute for Energy and Environmental Research. Welcome back to Living on Earth Arjun.

MAKHIJANI: Thank you, Steve. Glad to be back.

CURWOOD: So, this report from TEPCO seems serious, maybe even ominous. What what exactly is going on?

MAKHIJANI: Well, they are exploring the molten core of the reactor in reactor number two with robots, and the robot called Scorpion went farther into the bottom of the reactor in an area called “the pedestal” on which the reactor kind of sits and measured much higher levels of radiation than before. The highest level was 73 Sieverts per hour before and this time they measured a radiation level more than seven times higher. It doesn’t mean it’s going up. It just was in a new area of the molten core that had not been measured before.

CURWOOD: Still, it sounds to me like it’s problematic, that six years after this meltdown there’s such a high reading.

MAKHIJANI: It is a very high reading; they may encounter even higher readings. The difficulty with this high reading is that the prospect that workers can actually go there, even all suited up, becomes more and more remote. Robots are going to have to do all this work – That was mostly foreseen – but the radiation levels are so high that even robots cannot survive for very long. So now they’re going to have to go back to the drawing board and redesign robots that can survive longer or figure out how to do the work faster, and it’s going to be more costly and more complicated to decommission the site.

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The lid of Unit 4’s Primary Containment Vessel lies close to the reactor building. The reactor was shut down for maintenance at the time of the accident.

CURWOOD: Remind us, Arjun, please, of the human impact of this kind of radiation. What’s toxic to humans?

MAKHIJANI: Right. So, if you get high levels of radiation in a short period of time, four Sieverts is a lethal dose for about half the people within two months. So, in 530 Sieverts per hour would give you a lethal dose in less than 30 seconds.

CURWOOD: Wow.

MAKHIJANI: So, it’s a very, very, very high level of radiation. That’s why people cannot go into the reactor and work there. That’s not the end of the bad news, but that’s quite a bit of it.

CURWOOD: OK. All right, there is more bad news. I’m sitting down. Tell me.

MAKHIJANI: Yes, so the bottom of the reactor under the reactor there is a grating and then under the grating there’s the concrete floor, and what this robot discovered — It was supposed to go around the grating and survey the whole area, but it couldn’t because a piece of the grating was deformed and broken. So, now it appears that some of the molten fuel may have gone through the grating and maybe onto the concrete floor. We don’t know because even robotic surveys are now difficult, and a high radiation turns into heat, so the whole environment around the molten fuel is thermally very hot, and so whether it is going through the concrete, whether it is under the concrete, I don’t know that we have a good grip on that issue.

CURWOOD: So, Arjun, what’s going on with the reactors one and three? There have been published reports that TEPCO, Tokyo Electric Power Company that has these reactors, hasn’t really taken a good look at those reactors. What do you know?

MAKHIJANI: Well, they have to develop the robots, and I think that developing them, by looking at reactor two, and they’re finding these surprises, radiation levels much higher than previously measured. It shouldn’t actually be unanticipated. The big surprise here was that a part of the grating was gone, and so that the molten fuel would possibly have gone through the grating. So, I think similar surprises will await reactors one and three because each meltdown will have a different geometry.

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Storing contaminated water in tanks at the Fukushima Daiichi site presents an ongoing risk, says Makhijani.

URWOOD: So, now what about the decay products here? We’re starting with the Uranium family, but we wind up with Cesium and Strontium – Strontium 90. What risk is there of Strontium 90 getting into groundwater there?

MAKHIJANI: Yeah, so the peculiar thing about a nuclear reaction is the initial fuel, Uranium, is not very radioactive. It’s radioactive but you can hold the uranium fuel pellets in your hand without getting a high dose of radiation. After it’s gone through the nuclear reaction – Fission, that’s what generates the energy – the fission products which result from splitting the Uranium atom are much more radioactive than Uranium, and Strontium 90 and Cesium 137 are two of the products that last for quite a long time, half-life 30 years, and are quite toxic. So, Strontium 90 is specially a problem when it comes in to contact with water. It’s mobilized by water. It behaves like calcium, so if it gets into like sea water and get into the fish, the bones of the fish, or human beings, of course, it gets into the bone marrow and bone surface, increases the risk of cancer, leukemia. So it’s a pretty nasty substance, and Strontium 90 has been contacted with water. You know, rainwater goes and contacts the molten fuel. Groundwater may be contacting the molten fuel. So, we have had Strontium 90 contamination and discharges into the ocean. They also collect the water. They’ve got about more than 1,000 tanks of contaminated water stored at the Fukushima site. By my rough estimate may be about 100 million gallons of contaminated water is being stored there.

CURWOOD: What happens if there’s an earthquake?

MAKHIJANI: That’s exactly right. So about a week into the accident, I sent a suggestion to the Japan Atomic Energy Commission that they should buy a supertanker, put the contaminated water into the supertanker, and send it off elsewhere for processing. They do have a site in the north of Japan which was supposed to be for plutonium separation, but it could be used to support the cleanup of Fukushima. But they rejected that proposal more than once and decided to build these tanks instead. They have a decontamination process on-site, and there are a very vast number of plastic bags on the site filled with contaminated soil. Nobody wants the stuff and nobody knows what’s going to happen with it.

CURWOOD: It’s six years after the original meltdown. How much of a disaster is Fukushima today?

MAKHIJANI: Well, Fukushima is possibly the longest running, continuous industrial disaster in history. It has not stopped because the risks are still there. This is going to take decades to decommission the site, and then what is going to happen with all this highly radioactive waste, ‘specially the molten fuel? Nobody knows.

CURWOOD: Arjun Makhijani is President of the Institute for Energy and Environmental Research. Thanks for taking time with us today, Arjun.

MAKHIJANI: So good to be back with you, Steve.

http://www.loe.org/shows/segments.html?programID=17-P13-00007&segmentID=6

Six years on, Fukushima rests its hopes on fearless robots

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As the struggle continues to bring the six-year-old triple nuclear meltdown at Fukushima Daiichi under control, robots are providing a first, albeit expendable, line of assault.

The robots are on a high-tech suicide mission into the nooks and crannies beneath the stricken plant’s three melted-down reactor cores to discover and map an estimated yet elusive 600 tons of molten nuclear fuel.

Radiation levels in these corridors can reach up to 650 sieverts and hour, higher by nine times than the previous highs measured at the plant, which plateaued at a mere 73 sieverts in 2012.

A whole human body dose of 10 sieverts is enough to cause immediate illness and death within a few weeks at most, 650 within a minute.

Levels like those recently found in the snarls and wreckage beneath Fukushima’s reactor No 2, where radiation is more concentrated because, unlike reactor No 1 and 3, it didn’t suffer a hydrogen explosion, are lethal not just to humans but, as it turns out, to robots as well.

The most recent robot that Tokyo Electric Power Co., the owner of the Fukushima plant, sent into the breach of reactor No 2 died in less than a day. The two before that got stuck in narrow passages and were given up for dead, and a third was abandoned after it spent six days searching for the reactor’s melted fuel. Yet one more robot was sacrificed in action while trying to locate one of its lost compatriots.

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Scientists are trying to develop robots better suited to the high radiation intensity. Yet they say the metallic body count is producing results by giving technicians a view of where the melted down fuel is located and helping them produce 3-D models of what it looks like.

The hope is that robots will be doing the heavy lifting when it comes time to dig out the fuel on a decommissioning job now expected to last another 30 to 40 years at a new cost of $189 billion – nearly double estimates released three years ago.

But on behalf of the 6,000 human workers at the site: Better the robots than them.

Six years ago, on March 11, 2011 a 9.0 magnitude earthquake 72 kilometers out to sea slammed a 39-meter tsunami into the Fukushima Daiichi nuclear power plant, causing a triple meltdown. In the days that followed, uranium fuel melted down in three of the six reactors. Explosions in three of the reactor buildings belched radioactive iodine, cesium and other fission by-products into the environment.

In the immediate aftermath, Japan shut down its 42 remaining nuclear reactors. Up to 160,000 people who lived within a 20-kilometer radius of the plant were forced to evacuate homes where they had lived for generations with their families in agricultural Fukushima.

Six years later, the lemming-like march of robots into the still chaotic cleanup of the plant has become a hopeful metaphor for technology accomplishing what is beyond humanity’s grasp, and their deaths are getting a lot of attention.

Tepco is still hewing to its vow of securing the plant by 2050 to 2060, and says that for the first time since the accident it has succeeded in reeling in the threat the wrecked plant poses to the surrounding area. A visual example of that, noted by reporters who took their annual tour of the plant, is that the thousands of workers on site can now work in ordinary work clothes and surgical masks rather than protective gear. And there are fewer workers to count. Where 8,000 were working at the site last year, 2000 fewer are needed now.

Damaged reactor buildings have been reinforced and 1,300 precariously perched spent fuel assemblies at reactor No. 4 that were a potential disaster all their own have been safely removed. The ground has also been covered with a special coating to prevent rainwater from added to Tepco’s water management struggles.

The company’s projection that it will finish the cleanup in the next four decades, however, is viewed skeptically by Japan’s Nuclear Regulatory Authority, which recently told the Guardian newspaper that the effort was still groping in the dark. And many are suspicious that the Tepco’s optimism is just public relations to assure the international community ahead of the 2020 Tokyo Olympics.

Can you go home again?

Another looming nightmare for many thousands of people is the prospect of loosing government financial support if they don’t move back to villages and towns they evacuated, which many environmental groups say are still highly contaminated.

The evacuation orders enacted by Prime Minister Shinzo Abe’s government after the disaster will be stripped later this month, forcing the evacuees back to live in areas that where in the direct path of the disaster.

Abe’s government says it’s safe for people to return to areas where radiation is 20 millisieverts per year or lower. The globally-accepted limit for radiation absorption is 1 millisievert per year, though the IAEA says anything up to 20 millisieverts per year poses no immediate danger to humans. That has been disputed by numerous studies.

Water hazards

At the plant, contaminated water still poses one of the biggest threats to the wider environment. Nearly one million tons of it stored across 1,000 tanks that were collected after the reactors were blasted with seawater to cool them down. More water has poured in as technicians continue to circulate it through the destroyed reactors to keep them cool.

Leaks from these tanks have often contaminated groundwater, and Tepco has struggled to divert the radioactive deluge from spilling into the Pacific Ocean with an underground wall of frozen soil.

The wall looks a bit like the piping behind a refrigerator and sinks 30 meters into the ground. Over the last year, Tepco pumped water into it to begin the freezing process. But some reports say the wall is having less success in another of its tasks – holding back groundwater from leaking into the basements of reactor buildings, which creates yet more contaminated water.

At their six-year anniversary briefing to reporters, Tepco admitted it was conflicted over what to do with the sea it has amassed. The company says it will be able to cleanse much of the water of cesium, strontium and 50 other radionuclides. But they’re still stumped by how to get rid of tritium, a radioactive isotope of hydrogen, which is still in that water.

Tepco is studying two options. One is to simply dilute the water further and dump it into the sea, as tritium naturally occurs in water in microscopic quantities. They’re also considering evaporating all 960,000 tons of it to release the tritium into the atmosphere.

The company says the final decision will be subject to a public hearing process. Should dumping water into the sea – as has happened numerous times before – still be among the considerations, it would doubtless meet the fierce opposition of fishermen, who have struggled with contaminated seawater since the accident.

Robots’ maze hunt

But by far the most technically involved struggle is finding and removing the fuel that melted down in reactor Nos 1, 2 and 3. And for that, enter the robots, each of which has to be shaped to its task.

At reactor No. 2, where the robot crews have been doing most of their work, it’s not yet known if the fuel melted into or through the reactor vessel’s concrete floor. Determining where that fuel is, and how radioactive it is, dictates how the robots will be designed.

And that’s just for this reactor. At reactor Nos 1 and 3, robots will have to be further customized to handle the specifics of each location. With explorations underway at reactor No 2, Tepco says it expects more robots to march into the other reactors by this summer.

At that point, they say, they will set policy on how the melted fuel will be removed, a process that isn’t expect to begin until 2021.

Designing and building what Tepco refers to as “single function robots” takes as long as two years, and that’s only when you know what you are making the robots for.

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One of the robots currently on the drawing board, for instance, would be able to leap over debris. Another that Hitachi is reportedly designing will resemble a snake so it can lower cameras through a grating in reactor No 1 to scope out and photograph melted down fuel there. That will be third Hitachi robot of that design.

Another robot designed by Toshiba, which was widely eulogized throughout the media, was designed to the anatomy of a scorpion. It died at the end of February just shy of a grating through which it might have got a peek of melted down fuel in reactor No 2.

Newer robot designs, according to a Tepco spokesman who talked with Bloomberg, are incorporating fewer wires and circuits and are built with harder parts than their earlier cousins.

But even the robots that peter out in the radiation are providing valuable clues: Toshiba’s scorpion robot sent the first grainy images from within reactor No 2 of a black residue that could actually be the spent fuel it was sent in to find.

Whether the fuel is in discrete piles or has melted to the walls of its containment vessels will present yet new challenges. Tepco and other scientists expect it’s a bit of both. Fuel that oozed and then re-melted inside the core or adhered to other reactor structures will have to be cut out, shoveled up and placed in shielded containers before it can be removed. This will be the robots’ job.

Earning the trust of a suspicious public

Six years of work is doing little to dent public suspicion of nuclear power in a country that previously relied on its 54 reactors to supply 30 percent of its power.

Tepco – which last year was shown to have delayed reporting the initial meltdowns after the catastrophe by 88 days, thus jeopardizing tens of thousands of lives – has a long way to got before it regains trust. Numerous other independent scientists are said by Japanese activists to be massaging data to make the situation look better than it is.

The mistrust is visible both in how slowly Japan is allowing its nuclear reactors go back online, and by the trickle of people who are willing to return to homes in the Fukushima Prefecture from which they were evacuated.

Japan’s reactors, all of which were shut down in the wake of the disaster, must pass the world’s most stringent stress tests before utilities can consider switching them back on. But even after they’re cleared technically, the people living near the plants have to want them back – and not many do.

As of this year, only three nuclear reactors have been switched on since 2011. Two others at the Genkai nuclear power plant on Japan’s Kyushu Island, were green lighted by a local mayor, but now must be approved by seven other surrounding municipalities.

In the most recently available national polls, taken last year on the fifth anniversary of the disaster, 70 percent of the population opposes the reactor restarts.

Among the more than 160,000 people reckoning with the dilemma of moving back to areas affected by radiation, 60 percent report feeling physical, psychological, financial and emotional stress as a result of the disaster, Japan’s NHK television reported. Up to 72,500 of these people still live in government supplied temporary housing.

In Naime, only 4 kilometers northwest of the plant, more than half of the resident have elected not to return, according to government surveys. Levels there recently hover around 0.07 microsieverts per hour, but down the road in Tomioka, they spike to 1.48 microsieverts an hour, more than 30 times levels in downtown Tokyo, showing there are still lingering radiation hotspots.

One group that is not afraid of populating the ghost-towns surrounding the plant are, according to reports, wild boar. The animals, which have grown up without humans around have reportedly grown fearless.

Tamotsu Baba, the mayor of Naime who is pushing for resettlement by the end of the month, told Reuters the boars pose make the town even less hospitable than the threat of radiation.

http://bellona.org/news/nuclear-issues/2017-03-six-years-on-fukushima-rests-its-hopes-on-fearless-robots

Dying robots and failing hope: Fukushima clean-up falters six years after tsunami

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Exploration work inside the nuclear plant’s failed reactors has barely begun, with the scale of the task described as ‘almost beyond comprehension’

Barely a fifth of the way into their mission, the engineers monitoring the Scorpion’s progress conceded defeat. With a remote-controlled snip of its cable, the latest robot sent into the bowels of one of Fukushima Daiichi’s damaged reactors was cut loose, its progress stalled by lumps of fuel that overheated when the nuclear plant suffered a triple meltdown six years ago this week.

As the 60cm-long Toshiba robot, equipped with a pair of cameras and sensors to gauge radiation levels was left to its fate last month, the plant’s operator, Tokyo Electric Power (Tepco), attempted to play down the failure of yet another reconnaissance mission to determine the exact location and condition of the melted fuel.

Even though its mission had been aborted, the utility said, “valuable information was obtained which will help us determine the methods to eventually remove fuel debris”.

The Scorpion mishap, two hours into an exploration that was supposed to last 10 hours, underlined the scale and difficulty of decommissioning Fukushima Daiichi – an unprecedented undertaking one expert has described as “almost beyond comprehension”.

Cleaning up the plant, scene of the world’s worst nuclear disaster since Chernobyl after it was struck by a magnitude-9 earthquake and tsunami on the afternoon of 11 March 2011, is expected to take 30 to 40 years, at a cost Japan’s trade and industry ministry recently estimated at 21.5tr yen ($189bn).

The figure, which includes compensating tens of thousands of evacuees, is nearly double an estimate released three years ago.

The tsunami killed almost 19,000 people, most of them in areas north of Fukushima, and forced 160,000 people living near the plant to flee their homes. Six years on, only a small number have returned to areas deemed safe by the authorities.

Developing robots capable of penetrating the most dangerous parts of Fukushima Daiichi’s reactors – and spending enough time there to obtain crucial data – is proving a near-impossible challenge for Tepco. The Scorpion – so called because of its camera-mounted folding tail – “died” after stalling along a rail beneath the reactor pressure vessel, its path blocked by lumps of fuel and other debris.

The device, along with other robots, may also have been damaged by an unseen enemy: radiation. Before it was abandoned, its dosimeter indicated that radiation levels inside the No 2 containment vessel were at 250 sieverts an hour. In an earlier probe using a remote-controlled camera, radiation at about the same spot was as high as 650 sieverts an hour – enough to kill a human within a minute.

Shunji Uchida, the Fukushima Daiichi plant manager, concedes that Tepco acquired “limited” knowledge about the state of the melted fuel. “So far we’ve only managed to take a peek, as the last experiment with the robot didn’t go well,” he tells the Guardian and other media on a recent visit to the plant. “But we’re not thinking of another approach at this moment.”

Robotic mishaps aside, exploration work in the two other reactors, where radiation levels are even higher than in reactor No 2, has barely begun. There are plans to send a tiny waterproof robot into reactor No 1 in the next few weeks, but no date has been set for the more seriously damaged reactor No 3.

Naohiro Masuda, the president of Fukushima Daiichi’s decommissioning arm, says he wants another probe sent in before deciding on how to remove the melted fuel.

Despite the setbacks, Tepco insists it will begin extracting the melted fuel in 2021 – a decade after the disaster – after consulting government officials this summer.

But Shaun Burnie, a senior nuclear specialist at Greenpeace Germany who is based in Japan, describes the challenge confronting the utility as “unprecedented and almost beyond comprehension”, adding that the decommissioning schedule was “never realistic or credible”.

The latest aborted exploration of reactor No 2 “only reinforces that reality”, Burnie says. “Without a technical solution for dealing with unit one or three, unit two was seen as less challenging. So much of what is communicated to the public and media is speculation and wishful thinking on the part of industry and government.

The current schedule for the removal of hundreds of tons of molten nuclear fuel, the location and condition of which they still have no real understanding, was based on the timetable of prime minister [Shinzo] Abe in Tokyo and the nuclear industry – not the reality on the ground and based on sound engineering and science.”

Even Shunichi Tanaka, the chairman of Japan’s nuclear regulation authority, does not appear to share Tepco’s optimism that it will stick to its decommissioning roadmap. “It is still early to talk in such an optimistic way,” he says. “At the moment, we are still feeling around in the dark.”

The situation is not under control’

On the surface, much has changed since the Guardian’s first visit to Fukushima Daiichi five years ago.

Then, the site was still strewn with tsunami wreckage. Hoses, pipes and building materials covered the ground, as thousands of workers braved high radiation levels to bring a semblance of order to the scene of a nuclear disaster.

Six years later, damaged reactor buildings have been reinforced, and more than 1,300 spent fuel assemblies have been safely removed from a storage pool in reactor No 4. The ground has been covered with a special coating to prevent rainwater from adding to Tepco’s water-management woes.

Workers who once had to change into protective gear before they approached Fukushima Daiichi now wear light clothing and simple surgical masks in most areas of the plant. The 6,000 workers, including thousands of contract staff, can now eat hot meals and take breaks at a “rest house” that opened in 2015.

But further up the hill from the coastline, row upon row of steel tanks are a reminder of the decommissioning effort’s other great nemesis: contaminated water. The tanks now hold about 900,000 tons of water, with the quantity soon expected to reach 1m tons.

Tepco’s once-vaunted underground ice wall, built at a cost of 24.5bn yen, has so far failed to completely prevent groundwater from leaking into the reactor basements and mixing with radioactive coolant water.

The structure, which freezes the soil to a depth of 30 metres, is still allowing 150 tonnes of groundwater to seep into the reactor basements every day, said Yuichi Okamura, a Tepco spokesman. Five sections have been kept open deliberately to prevent water inside the reactor basements from rising and flowing out more rapidly. “We have to close the wall gradually,” Okamura said. “By April we want to keep the influx of groundwater to about 100 tonnes a day, and to eliminate all contaminated water on the site by 2020.”

Critics of the clean-up note that 2020 is the year Tokyo is due to host the Olympics, having been awarded the Games after Abe assured the International Olympic Committee that Fukushima was “under control”.

Mitsuhiko Tanaka, a former Babcock-Hitachi nuclear engineer, accuses Abe and other government officials of playing down the severity of the decommissioning challenge in an attempt to win public support for the restart of nuclear reactors across the country.

Abe said Fukushima was under control when he went overseas to promote the Tokyo Olympics, but he never said anything like that in Japan,” says Tanaka. “Anyone here could see that the situation was not under control.

If people of Abe’s stature repeat something often enough, it becomes accepted as the truth.”

https://www.theguardian.com/world/2017/mar/09/fukushima-nuclear-cleanup-falters-six-years-after-tsunami

Inside the Fukushima nuclear station: robots are not good enough

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The robots sent in to investigate the nuclear fallout at Fukushima just aren’t good enough.

Tokyo Electric Power Company’s (TEPCO) head of decommissioning admitted on Thursday that more creativity was needed in developing its robots sent to the reactive zone.

The Fukushima nuclear power plant was massively damaged in 2011, when three of the six nuclear reactors suffered meltdown after being struck by a 9.0-magnitude earthquake and associated tsunami waves.

More than 100,000 residents of the nearby Fukushima Prefecture had to be relocated, and the government has spent the last five years struggling with the aftermath. The incident is regarded as the world’s largest nuclear disaster since Chernobyl.

Part of the clean-up includes robots, sent in to probe the site, because radiation levels are too high for humans.

But earlier last month, a robot sent into Fukushima’s No. 2 reactor was forced to abort its mission after it was blocked by deposits — believed to be a mixture of melted fuel and broken pieces of structure.

Two previous robots had also failed in its missions after one was stuck in a gap and another was abandoned after being unable to find fuel during six days of searching.

This is an example of one of the robots TEPCO had sent to probe the area in the past.

“We should think out of the box so we can examine the bottom of the core and how melted fuel debris spread out,” TEPCO Head of Decommissioning Naohiro Masuda said.

Mr Masuda also added that he wants another robot sent in before deciding on methods to remove the reactor’s debris.

Despite the failed probe missions, officials have added that they want to stick to their schedule of starting the site clean up in 2021.

Decommissioning the site is expected to cost tens of billions of dollars and last around 40 years.

Fukushima’s No. 2 reactor was found in February to have a radiation level of 530 sieverts.

Exposure to four sieverts is enough to be lethal, according to the National Institute of Radiological Sciences.

South Korea’s low-cost carrier Jeju Air also announced on Tuesday that it would not use Fukushima Airport due to fears of radiation.

Some of its customers had reportedly posted online that they would not use the airline because they didn’t want to “board airplanes that flew over Fukushima.”

http://mashable.com/2017/03/03/fukushima-robots-fail/#faftQ3d8d5qt

As evacuees move back, Fukushima cleanup faces daunting obstacles

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Workers decontaminate a forest near Fukushima in Japan.

 

TOKYO—Six years into a decommissioning effort expected to last into the 2050s, an official leading the work on the stricken Fukushima Daiichi Nuclear Power Plant claims that cleanup crews are making “steadfast progress.” But thorny technical obstacles must be overcome.

The 9.0-magnitude earthquake off Japan’s northeast coast on 11 March 2011 triggered one of the history’ s most devastating tsunamis. The one-two punch killed nearly 16,000 people, left more than 2500 missing, and wiped out infrastructure in coastal communities.

The tsunami also knocked out Fukushima’s systems for cooling its nuclear reactors, causing core meltdowns in three of the plant’s six reactors. Hydrogen explosions blew out the walls and roofs of the buildings housing units 1, 2, and 3, releasing massive amounts of radiation. Much of the contamination was swept into the Pacific Ocean, but winds deposited fallout over parts of northeastern Japan. Some 160,000 people living near the plant were evacuated or fled on their own.

On the eve of the sixth anniversary of the disaster, officials took pride in what they view as successful efforts to minimize the health threat to surrounding communities. Radiation from the crippled reactors is no longer having an impact outside the plant, Naohiro Masuda, head of decommissioning for Fukushima owner Tokyo Electric Power Co. (TEPCO), said today at a briefing here. He noted that evacuated residents are returning to their homes as decontamination work reduces exposure levels below thresholds. At the power plant, radiation levels are now so low that the 6000 workers slowly demolishing the damaged reactor halls need only wear typical construction site safety gear except when working near the three reactors that suffered meltdowns. And radiation levels just offshore remain below the limit for drinking water set by the World Health Organization, Masuda said. Given the progress, he reiterated that TEPCO is confident they can stick to a previously set roadmap that envisions completing the decommissioning 30 to 40 years after the accident. But doing so won’t be cheap. Last December, Japan’s Ministry of Economy, Trade and Industry revised its estimate of the total cost of decommissioning up to $188 billion.

Stemming ocean contamination has been a thorny challenge. Since early in the crisis, crews have circulated water through the damaged reactors to prevent overheating that could lead to further fuel melting. That water, and groundwater flowing through the site is heavily contaminated and TEPCO has struggled to keep it from seeping into the Pacific. Schemes to divert groundwater away from the plant and freeze a wall of soil around the reactors down to bedrock—to contain contaminated water—have minimized leaks, Masuda said.

In the meantime, TEPCO has accumulated 960,000 tons of contaminated water stored in 1000 10-meter-tall tanks at the site. TEPCO has removed cesium, strontium, and more than 50 other radionuclides from that water. But they have been stymied by tritium, a radioactive hydrogen isotope in the water. Several experimental approaches to removing the tritium “were judged to be impractical,” Masuda said.

Tritium occurs naturally in water but in minuscule concentrations. Simply releasing the tritium-laden water, perhaps after further dilution is one disposal option, Masuda said. Another would be to evaporate the water, releasing some tritium into the atmosphere, as was done at the Three Mile Island nuclear plant in Pennsylvania after its 1979 accident. An advisory committee is now studying the problem and will hold discussions with local communities “so TEPCO will be able to act in a responsible manner in dealing with the tritium,” Masuda said.

Another major hurdle is determining the condition and location of the melted fuel, much of which is believed to have dropped to the bottoms of the containment vessels where high radiation levels preclude human entry. Robotic investigations are proving problematic. In January, the camera on a robotic probe sent into the Unit 2 containment vessel was fried by radiation, though it did return important images before its demise. Then last month, a small robot on tanklike treads was sent through a 10-centimeter-diameter pipe into the vessel to investigate the presumed location of the damaged fuel. But it got tangled up in debris and was abandoned.

TEPCO is now thinking it might need a robot able to jump over debris. And they are planning robotic investigations of the units 1 and 3 containment vessels in preparation for a planning session this summer to set a policy for recovering the melted fuel. 

http://www.sciencemag.org/news/2017/03/evacuees-move-back-fukushima-cleanup-faces-daunting-obstacles

Fukushima cleanup chief urges better use of probe robot

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Naohiro Masuda, head of decommissioning the damaged Fukushima nuclear plant, speaks at a news conference in Tokyo on March 2, 2017.

TOKYO (AP) — The head of decommissioning for the damaged Fukushima nuclear plant said Thursday that more creativity is needed in developing robots to locate and assess the condition of melted fuel rods.

Naohiro Masuda, president of Fukushima Dai-ichi decommissioning, said Thursday that more data is needed so they can develop a better strategy for removing debris. The plant’s operator, Tokyo Electric Power Co., and the government will decide on a method this summer.

Masuda said that a robot sent inside the Unit 2 containment vessel last month could not reach as close to the core area as hoped, because it was blocked on its planned route by deposits, believed to be mixture of melted fuel and broken pieces of equipment.

Masuda said he wants another probe sent in before deciding on methods to remove the reactor’s debris.

TEPCO needs to know the melted fuel’s exact location as well as structural damage in each of the three wrecked reactors to figure out the best and safest ways to remove the fuel.

Despite the incomplete probe missions, officials have said they want to stick to their schedule to determine the removal methods this summer and start work in 2021.

Unit 2 is one of the Fukushima reactors that melted down following the 2011 earthquake and tsunami. The unit had less damage to its containment vessel, so internal probes there are ahead of the other two reactors.

Still, the earlier probes have suggested worse-than-anticipated challenges for the plant’s cleanup, which is expected to take decades.

Similar probes are being planned for the other two reactors. A tiny waterproof robot will be sent into Unit 1 in coming weeks, while experts are still trying to figure out a way to access the badly damaged Unit 3.

TEPCO is struggling with the plant’s decommissioning. The 2011 meltdown forced tens of thousands of nearby residents to evacuate their homes, and many have still not been able to return home due to high radiation levels.

Images captured from inside the chamber show damage, and structures coated with molten material, possibly mixed with melted nuclear fuel.

http://mainichi.jp/english/articles/20170302/p2g/00m/0dm/076000c