Where to put all the radioactive waste is now the burning issue

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The call might have been made to decommission five over-the-hill nuclear reactors, but the problem remains of where to dispose of their total 26,820 tons of radioactive waste.

The plant operators have yet to find disposal sites, and few local governments are expected to volunteer to store the waste on their properties.

The decommissioning plans for the five reactors that first went into service more than 40 years ago was green-lighted by the Nuclear Regulation Authority on April 19.

It is the first NRA approval for decommissioning since the 2011 Fukushima nuclear disaster triggered by the Great East Japan earthquake and tsunami.

That disaster led to a new regulation putting a 40-year cap, in principle, on the operating life span of reactors.

The reactors to be decommissioned are the No. 1 reactor at Japan Atomic Power Co.’s Tsuruga plant in Fukui Prefecture; the No. 1 reactor at Kyushu Electric Power Co.’s Genkai plant in Saga Prefecture; the No. 1 and No. 2 reactors at Kansai Electric Power Co.’s Mihama plant in Fukui Prefecture; and the No. 1 reactor at Chugoku Electric Power Co.’s Shimane plant in Shimane Prefecture.

The decommissioning will be completed between fiscal 2039 and fiscal 2045 at a total cost of 178.9 billion yen ($1.64 billion), according to the utilities.

In the process, the projects are expected to produce 26,820 tons of radioactive waste–reactors and pipes included.

An additional 40,300 tons of waste, such as scrap construction material, will be handled as nonradioactive waste due to radiation doses deemed lower than the government safety limit.

Securing disposal sites for radioactive waste has proved a big headache for utilities.

About 110 tons of relatively high-level in potency radioactive waste, including control rods, are projected to pile up from the decommissioning of the No. 1 reactor at the Mihama plant.

Such waste needs to be buried underground deeper than 70 meters from the surface and managed for 100,000 years, according to the NRA’s guidelines.

In addition, the decommissioning of the same reactor will generate 2,230 tons of less toxic waste as well, including pipes and steam generators.

Under the current setup, utilities must secure disposal sites on their own.

Kansai Electric, the operator of the Mihama plant, has pledged to find a disposal site “by the time the decommissioning is completed.”

But Fukui Prefecture, which hosts that plant and others, is demanding the waste from the Mihama facility be disposed of outside its borders.

The project to dismantle the reactor and other facilities has been postponed at Japan Atomic Power’s Tokai plant in Ibaraki Prefecture because the company could not find a disposal site for the relatively high-level waste.

The decommissioning of the reactor had been under way there since before the Fukushima disaster.

The expected difficulty of securing disposal sites could jeopardize the decommissioning timetable, experts say.

Even finding a disposal site for waste that will be handled as nonradioactive has made little headway.

What is more daunting is the hunt for a place to store high-level radioactive waste that will be generated during the reprocessing of spent fuel, they said.

http://www.asahi.com/ajw/articles/AJ201704200039.html

Japan to scrap 5 more nuclear reactors

String of facilities approaching maximum life span

0420N-Decommissioning-Business_article_main_image.jpgWorkers take apart a pump at Chubu Electric Power’s Hamaoka nuclear plant.

TOKYO — Five nuclear reactors in Japan were approved for decommissioning on Wednesday, pushing utilities and other companies to join hands to tackle both the great business opportunities and daunting technical problems involved with the process.

Two reactors at Kansai Electric Power‘s Mihama plant, as well as one each at Japan Atomic Power’s Tsuruga plant, Chugoku Electric Power‘s Shimane plant and Kyushu Electric Power‘s Genkai facility received the green light from Japan’s Nuclear Regulation Authority. The safety updates needed to keep them running beyond their mandated 40-year life span were deemed too costly.

Japan had 54 nuclear reactors before the 2011 meltdown at the Fukushima Daiichi nuclear plant. A total of 15, including the six at Fukushima Daiichi, are now set to be taken out of service. Another one or two will be brushing up against the 40-year limit every year, unless one-time, 20-year extensions are sought and granted.

Companies now face a pressing need to acquire expertise on dismantling reactors and disposing of radioactive materials. No commercial nuclear reactor has ever been decommissioned in Japan before, and utilities are looking for partners with the necessary capabilities.

Kansai Electric is seeking help from France’s Areva and Japan’s Mitsubishi Heavy Industries in decommissioning the Nos. 1 and 2 reactors at Mihama, particularly in decontaminating pipes and equipment. Japan Atomic Power and U.S.-based EnergySolutions signed an agreement last spring to cooperate on the former’s Tsuruga plant.

Japanese utilities are also beginning to work with each other. Kansai Electric entered a partnership last year with Kyushu Electric, Chugoku Electric and Shikoku Electric Power. The four plan to cut decommissioning costs by jointly procuring materials and sharing technology and staffers. 

Other players are also angling for a piece of the pie. Two years ago, Mitsubishi Heavy set up a department specializing in dismantling nuclear reactors. The company was a key player in building the Mihama and Genkai reactors, and wants a lead role in taking them apart. Japanese general contractor Shimizu also signed a technical cooperation agreement with U.K.-based Cavendish Nuclear.

Utilities have increased their rates in order to raise the necessary funds to decommission the five newly approved reactors. They have already come up with about 160 billion yen ($1.47 billion) of the estimated 180 billion yen total. But the process will likely take two or three decades, and costs could easily grow.

The utilities may also face significant challenges to disposing of the roughly 27,000 tons of contaminated waste the five reactors are expected to generate. For example, Japan Atomic Power wants to bury less radioactive materials at the site of the Tokai nuclear plant, one of the earlier plants approved for decommissioning, but faces strong local opposition.

Relevant legislation has not been finalized either. Highly contaminated materials are supposed to be buried more than 70 meters below ground. But the Nuclear Regulation Authority has only just begun debating exactly how they should be buried.

http://asia.nikkei.com/Politics-Economy/Policy-Politics/Japan-to-scrap-5-more-nuclear-reactors

5 Reactors Decommissioning Approved

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Decommissioning plans for 5 reactors approved

Japan’s nuclear regulator has approved plans submitted by operators of 4 power plants to decommission 5 aging nuclear reactors. The reactors are to be scrapped in a process lasting up to nearly 30 years.

The Nuclear Regulation Authority approved the plans at a meeting on Wednesday.

Under a government policy introduced after the 2011 nuclear accident at the Fukushima Daiichi plant, reactor lifespan was limited to 40 years in principle.

In 2015, utility companies decided to dismantle the 5 reactors. The 5 include 2 reactors at the Mihama plant and one at the Tsuruga plant, both in Fukui Prefecture, one at the Shimane plant in Shimane Prefecture and one at the Genkai plant in Saga Prefecture.

The plans call for first decontaminating pipes and dismantling facilities that are free of radioactive contamination.

The operators assume that the reactors and their buildings will be taken down and removed by fiscal 2045 at the latest.

At issue is where to put control rods, reactor parts and other radioactive waste. No site for a final disposal facility has been designated.

The regulator is checking another decommissioning plan for a reactor at the Ikata plant in Ehime Prefecture. The facility’s operator decided last year to dismantle it.

https://www3.nhk.or.jp/nhkworld/en/news/20170419_18/

 

Nuclear authority approves decommissioning plans for 5 aging reactors

TOKYO (Kyodo) — Japan’s nuclear authority approved decommissioning plans for five aging reactors at four power plants on Wednesday, the first such approvals since a government regulation was implemented after the 2011 Fukushima disaster to stop the operation of reactors beyond 40 years.

The five reactors are the Nos. 1 and 2 units at Kansai Electric Power Co.’s Mihama plant in Fukui Prefecture, the No. 1 unit at Japan Atomic Power Co.’s Tsuruga plant in Fukui Prefecture, the No. 1 unit at Chugoku Electric Power Co.’s Shimane plant in Shimane Prefecture and the No. 1 unit at Kyushu Electric Power Co.’s Genkai plant in Saga Prefecture.

While the utilities indicated it will take about 30 years to complete the decommissioning of each reactor, the disposal sites for the radioactive waste from the facilities have yet to be determined.

The decommissioning work will involve removing spent fuel from pools, dismantling reactors and demolishing surrounding facilities.

The regulation brought in following the 2011 disaster at Tokyo Electric Power Co.’s Fukushima Daiichi plant prohibits nuclear reactors from operating for over 40 years in principle, but the Nuclear Regulation Authority can approve the operation of a unit for up to 20 more years if the operator makes safety upgrades and the unit passes screening.

It was decided in March 2015 to scrap the five reactors, mainly due to profitability, as huge amounts of additional investment would be needed to meet the new safety requirements to keep the reactors operating beyond 40 years.

Meanwhile, the authority has given approval for the extended operation of the No. 3 unit at Kansai Electric’s Mihama plant as well as the Nos. 1 and 2 units at its Takahama plant in Fukui Prefecture, which are also around 40 years old.

The authority is currently examining Shikoku Electric Power Co.’s decommissioning plan for the No. 1 unit at the Ikata plant in Ehime Prefecture, after the utility decided in March 2016 to scrap the reactor.

In Wednesday’s meeting, the authority also decided that Japan Nuclear Fuel Ltd.’s uranium enrichment facility in the village of Rokkasho, Aomori Prefecture, satisfies regulatory requirements, virtually giving a green light for its operation. The decision will become official after consultation with the industry minister.

It will become the second fuel plant to clear new regulatory requirements after Global Nuclear Fuel-Japan Co.’s plant in Kanagawa Prefecture.

http://mainichi.jp/english/articles/20170419/p2g/00m/0dm/079000c

Robots expected to play key role in Fukushima decommissioning, but challenges remain

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As decommissioning work at Tokyo Electric Power Co. (TEPCO)’s Fukushima No. 1 Nuclear Power Plant continues, remote control robots are expected to play an important role in the decommissioning process. However, it is impossible to ignore the fact that the development of these robots faces huge challenges, such as high levels of radiation within the nuclear reactors, as well as a lack of information.

Among the robots that have been designed to carry out decommissioning work is the “muscle robot.” Developed by Hitachi-GE Nuclear Energy, Ltd., the body and limbs of the muscle robot can be controlled with a device that one might typically find attached to a video game console. Another type of robot acts like a crab with claws that can be used to grasp metallic pipes and snap them using a blade positioned on one of its claws. These robots are also able to smash concrete, using a special drill that can be placed at the end of the arm — like something out of a Hollywood movie.

Looking ahead, the government and TEPCO are aiming to start removing the melted nuclear fuel inside the No. 1 to No. 3 reactors at the Fukushima No. 1 nuclear plant in 2021, after announcing exactly how they plan to do so over the summer. Although knowledge regarding the matter is limited, it seems that the melted nuclear fuel in the reactors has cooled and solidified, and the prototypes of the robots have been produced based on the assumption that the devices need to break down and remove such hardened fuel.

The robots’ parts are connected together with springs, and are driven using hydraulic power. One of the main advantages of this system is that they are hardly affected by radiation. There are six types of robot in total, such as the “spider-style” robot which has six arms and legs (length 2.8 meters, width 2 meters, weight 50 kilograms), as well as a “tank-style” robot (length 4.35 meters, width 63 centimeters, weight 700 kilograms), which runs on a conveyor belt. The tank-style robot is capable of lifting objects weighing up to 50 kilograms. A representative from Hitachi-GE Nuclear Energy states determinedly, “I want the muscle robots to remove the melted nuclear fuel.”

However, the process will not be plain sailing. While the bodies of these robots are resistant to radiation, their cameras are somewhat vulnerable. It has been found that the electronic hardware in the cameras breaks easily after being exposed to radiation. For example, when a “cleaning robot” was sent into the No. 2 reactor on Feb. 9, 2017, the camera broke after about two hours after being exposed up to an estimated 650 sieverts per hour of radiation. The camera part of the robot is essential because without it, images cannot be transmitted back to the control room.

To solve this problem, ideas such as placing a metallic plate near the camera that would block out radiation have been discussed, but it is feared that this would make the robot heavier and interfere with its operations. As a Hitachi representative states, “If one were to use an analogy to describe the current development stage in human terms, then we have entered elementary school. We’d like to continue our work, believing we can develop usable robots.” It is clear that a trial-and-error process is very much underway, as the robot developers try their best to achieve perfection.

It will not be an easy road though. Hajime Asama, professor at the University of Tokyo and a member of the Technology Advisory Committee of the International Research Institute for Nuclear Decommissioning (IRID), states, “Robots are usually developed based on confirmation of what exactly lies in the reactors. However, in the case of the No. 1 power plant, no matter how hard you try to predict what is in there, there are often unexpected elements waiting.”

In the No. 2 reactor, a “scorpion-style robot” was sent in on Feb. 16, as a follow-up to the cleaning robot but it got trapped by deposits on the conveyor belt, and came to a halt. The presence of these kinds of deposits was unexpected at the stage when the robot was being designed. Too much is still unknown about the situation inside the reactors, making robot design difficult. Later this month, a “wakasagi ice fishing-type robot” is expected to be placed inside the No. 1 reactor, but it is feared that the same problems that were experienced in the No. 2 reactor will emerge once again.

In recent years, the use of artificial intelligence has been expected to play a key role but a number of unexpected problems have made progress in this area difficult. What is needed is technology that can be controlled remotely by people with flexible judgment. However, professor Asama believes that, “The reactors inside the No. 1 plant are full of unknown challenges. We have no choice but to use our available knowledge to create robots that can deal with these problems.”

https://mainichi.jp/english/articles/20170408/p2a/00m/0na/023000c

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