Fukushima: No End in Sight

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KGO Radio: Host Pat Thurston recently interviewed Arnie Gundersen, chief engineer for Fairewinds Energy Education on KGO radio to discuss the latest challenging news from Japan about the Fukushima Daiichi atomic power reactor including the high levels of radiation emanating from the reactors, all the failed robotic expeditions, where we should go from here, as well as how ongoing radioactive releases from the Fukushima Daiichi site may be impacting the west coast of the United States.

 

BBC Newsday: BBC Radio interviewed nuclear engineer Arnie Gundersen to discuss TEPCO’s attempts to send a special robot into Fukushima Daiichi Reactor #2 in Japan to investigate the obstacles in the way of TEPCO’s progress determining the location and condition of the atomic fuel. Unfortunately even this specially designed robot failed in its attempt to clear the path for additional investigations as the nuclear radioactivity was so high, it shut down the robots before they could complete their mission.

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Enviro News: The astronomical radiation readings at Fukushima Daiichi Reactor #2 of 530 Sv/hr complicate the already complex task of decommissioning the plant. These levels are so radioactive that a human would be dead within a minute of exposure and specially designed robots can only survive for about 2 hours. Fairewinds chief engineer Arnie Gundersen says that the best solution would be to entomb the reactors, similar to the sarcophagus entombing Chernobyl, for at least 100-years, otherwise the radiation level that workers would be exposed to is simply too dangerous.
Read the whole article here

 

Follow The Money: Whats Up With Fukushima Decommissioning

 

Are the meltdowns at Fukushima Daiichi over? The answer is no. Made all the more prevalent a year out from it’s initial release by the recent robotic expeditions into Reactor #2 which gave us a clearer picture on just how deadly the radiation levels are, watch Chief Engineer and nuclear expert Arnie Gundersen inform viewers on what’s going on at the Japanese nuclear meltdown site, Fukushima Daiichi. As the Japanese government and utility owner Tokyo Electric Power Company push for the quick decommissioning and dismantling of this man-made disaster, the press and scientists need to ask, “Why is the Ukrainian government waiting at least 100 years to attempt to decommission Chernobyl, while the Japanese Government and TEPCO claim that Fukushima Daiichi will be decommissioned and dismantled during the next 30 years?”
Like so many big government + big business controversies, the answer has nothing to do with science, and everything to do with politics and money. To understand Fukushima Daiichi, you need to follow the money.

http://www.fairewinds.org/newsletter-archive//no-end-in-sight

Fukushima nuclear disaster evacuees ‘pressured’ to return to contaminated homes, says Greenpeace

Even though radiation levels in a village near the site of the Fukushima nuclear disaster still exceed international guidelines, its evacuated residents are being coerced to return, according to a Greenpeace report.

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Residents from the Japanese ghost village of Iitate will be allowed to return to their former homes at the end of March – the first time since they were forced to flee the Fukushima nuclear disaster in 2011. That’s the date the Japanese government has set to lift evacuation orders.

But according to environmental organization Greenpeace, it’s uncertain whether many will want to. Greenpeace says tests it has carried out on homes in Iitate show that despite decontamination, radiation levels are still dangerously high – but that’s not stopping the Japanese governmenment from pressuring evacuees from returning, under threat of losing financial support.

Those who refuse to go back to their former homes, and are dependent on the Japanese government’s financial help, are faced with a dilemma. After a year from when an area is declared safe again to live in, evacuated residents will see their compensation payments terminated by the government.

Radiation ‘comparable with Chernobyl’

The nuclear disaster led to more than 160,000 people being evacuated and displaced from their homes. Of these, many tens of thousands are still living in temporary accommodation six years on.

The village of Iitate, lying northwest of the destroyed reactors at Fukushima Daiichi power plantand from which 6,000 citizens had to be evacuated, was one of the most heavily contaminated following the nuclear disaster.

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Government employees monitor radiation at a day-care center in Iitate in 2011

Around 75 per cent of Iitate is mountainous forest, an integral part of residents’ lives before the nuclear accident.

But according to Greenpeace’s report, published on Tuesday, radiation levels in these woods are “comparable to the current levels within the Chernobyl 30km exclusion zone – an area that more than 30 years after the accident remains formally closed to habitation.”

Put another way, Greenpeace said that in 2017, there clearly remains a radiological emergency within Iitate – defining emergency thus: “If these radiation levels were measured in a nuclear facility, not Iitate, prompt action would be required by the authorities to mitigate serious adverse consequences for human health and safety, property or the environment.”

The environmental organization says decontamination efforts have primarily focused on the areas immediately around peoples’ homes, in agricultural fields and in 20-meter strips along public roads.

But these efforts ended up generating millions of tons of nuclear waste – these now lie at thousands of locations across the prefecture, but they haven’t reduced the level of radiation in Iitate “to levels that are safe,” says Greenpeace.

‘Normalizing’ nuclear disaster?

The organization has accused the Japanese government of trying “to normalize a nuclear disaster, creating the myth that just years after the widespread radioactive contamination caused by the nuclear accident of 11 March 2011, people’s lives and communities can be restored and reclaimed.

“By doing so, it hopes, over time, to overcome public resistance to nuclear power.”

Greenpeace also lambasted the government for leaving unanswered what it calls a critical question for those trying to decide whether to return or not: what radiation dose will they be subjected to, not just in one year but over decades or a lifetime?

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Greenpeace says Japan’s government wants to restore public confidence in nuclear power at the cost of harming residents

“Until now the Japanese government has exclusively focused on annual radiation exposure and not the potential radiation dose rates returning citizens could potentially face over their entire lifetime,” says Greenpeace.

Greenpeace, which has been monitoring Iitate since 2011, carried out its latest survey in November 2016

It found that the average radiation dose range for Iitate beginning from March 2017 over a 70-year lifetime was between 39 millisieverts (mSv) and 183mSv – and that’s not including natural radiation exposure expected over a lifetime, or the exposure received in the days, weeks and months following the March 2011 nuclear disaster.

That exceeds yearly guidelines set by the International Commission on Radiological Protection (ICRP) when added up over a 70-year period – it puts the maximum recommended radiation exposure at 1mSv annually.

Greenpeace says: “The highly complex radiological emergency situation in Iitate, and with a high degree of uncertainty and unknown risks, means that there is no return to normal in Iitate, Fukushima prefecture.”

It has called on the Japanese government to cease its return policy, and to provide full financial support to evacuees, and “allow citizens to decide whether to return or relocate free from duress and financial coercion.”

According to Greenpeace, “for the more than 6,000 citizens of Iitate, this is a time of uncertainty and anxiety.”

Heinz Smital, nuclear physicist and radiation expert at Greenpeace Germany, and part of the team taking measurements at Iitate, told DW the residents were faced with a very difficult situation.

“If you decide to live elsewhere [and not return to Iitate], then you don’t have money, you’re sometimes not welcomed in another area so you are forced to leave, because people say, ‘you’re not going back but you could go back,'” he said. “But for people who go back, they have contaminated land, so how can they use the fields for agriculture?”

He urged the Japanese government to more involve those affected in the decision-making process and not try to give an impression that things are “going back to normal.”

“It’s a violation of human rights to force people into such a situation because they haven’t done anything wrong, it’s the operator of the power plant responsible for the damage it caused,” said Smital.

“It’s very clear that there’s very serious damage to the property and the lifestyle of the people but the government doesn’t care about this.”

http://www.dw.com/en/fukushima-nuclear-disaster-evacuees-pressured-to-return-to-contaminated-homes-says-greenpeace/a-37639353

FOCUS: Failed Survey Complicates N-Fuel Removal at Fukushima Plant

It looks like its too radioactive for robots to survive. I wonder how they will do this work now?

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Tokyo, Feb. 20 (Jiji Press)–A failed robot survey of melted nuclear fuel that has dropped through the bottom of a damaged reactor pressure chamber at the Fukushima No. 1 nuclear plant complicates the formulation of a policy in the summer for taking out the fuel debris.
The removal of the molten nuclear fuel is regarded as the most demanding challenge in the decommissioning of the disaster-stricken plant’s reactors, said to take 30 to 40 years.
Tokyo Electric Power Company Holdings Co. <9501>, the manager of the plant in Fukushima Prefecture, northeastern Japan, is discussing the drawing up of a broad policy outline before conducting an additional survey to work out a detailed plan for the nuclear fuel removal, company officials said.
TEPCO’s initial plan called for a self-propelled survey robot, dubbed scorpion, to enter the No. 2 reactor’s containment vessel and travel on a 7.2-meter rail to reach a metal grating directly beneath the reactor’s damaged pressure chamber. The robot would have surveyed the extent of damage to the chamber, while locating melted nuclear fuel that is believed to have dropped through the metal grating to the bottom of the containment vessel and shooting the fuel’s images.
The No. 2 reactor is one of the three units that suffered meltdown due to the failure of their cooling systems caused by the March 2011 earthquake and tsunami.

http://jen.jiji.com/jc/eng?g=eco&k=2017022000007

Melted Nuclear Fuel Search Proceeds One Dead Robot at a Time

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The latest robot seeking to find the 600 tons of nuclear fuel and debris that melted down six year ago in Japan’s wrecked Fukushima Dai-Ichi power plant met its end in less than a day.

The scorpion-shaped machine, built by Toshiba Corp., entered the No. 2 reactor core Thursday and stopped 3 meters (9.8 feet) short of a grate that would have provided a view of where fuel residue is suspected to have gathered. Two previous robots aborted similar missions after one got stuck in a gap and another was abandoned after finding no fuel in six days.

After spending most of the time since the 2011 disaster containing radiation and limiting ground water contamination, scientists still don’t have all the information they need for a cleanup that the Japanese government estimates will take four decades and cost 8 trillion yen ($70.6 billion). It’s not yet known if the fuel melted into or through the containment vessel’s concrete floor, and determining the fuel’s radioactivity and location is crucial to inventing the technology needed to remove it. 

The roadmap for removing the fuel is going to be long, 2020 and beyond,” Jacopo Buongiorno, a professor of nuclear science and engineering at the Massachusetts Institute of Technology, said in an e-mail. “The re-solidified fuel is likely stuck to the vessel wall and vessel internal structures. So the debris have to be cut, scooped, put into a sealed and shielded container and then extracted from the containment vessel. All done by robots.”

Read more: Robots are being utilized to clean up U.K.’s nuclear waste

To enter a primary containment vessel, which measures about 20 meters at its widest, more than 30 meters tall and is encased in meters of concrete, outside air pressure is increased to keep radiation from escaping and a sealed hole is opened that the robot passes through. Three reactors at the plant suffered meltdowns, and each poses different challenges and requires a custom approach for locating and removing the fuel, said Tatsuhiro Yamagishi, Tokyo Electric Power Co. Holdings Inc. spokesman.

The machines are built with specially hardened parts and minimal electronic circuitry so that they can withstand radiation, if only for a few hours at a time. Thursday’s mission ended after the robot’s left roller-belt failed, according to Tokyo Electric, better known as Tepco. Even if it had returned, this robot, like all others so far designed to aid the search for the lost fuel, was expected to find its final resting place inside a reactor.

No. 1 Unit

Hitachi Corp. in the next two months plans to send a machine into the No. 1 reactor core that scientists hope can transmit photos of the fuel and measure radiation levels.

The snake-like robot will lower a camera on a wire from a grate platform in the reactor to take photos and generate 3-D models of the bottom of the containment vessel. This will be the third time Hitachi sends in this robot design.

While the company is hopeful this robot will find some of the fuel, it will likely be unable to find all of it, according to Satoshi Okada, a Hitachi engineer working on the project. The company is already planning the next robot voyage for after April.

We are gathering information so that we can decide on a way to remove the fuel,” said Okada. “Once we understand the situation inside, we will be able to see the way to remove the fuel.”

No. 2 Unit

On Thursday, Toshiba’s scorpion-like robot entered the reactor and stopped short of making it onto the containment vessel’s grate. While Tepco decided not to retrieve it, the company views the attempt as progress.

We got a very good hint as to where the fuel could be from this entire expedition” Tepco official Yuichi Okamura said Thursday at a briefing in Tokyo. “I consider this a success, a big success.”

Tepco released images last month of a grate under the No. 2 reactor covered in black residue that may be the melted fuel — one of the strongest clues yet to its location. The company measured radiation levels of around 650 sieverts per hour through the sound-noise in the video, the highest so far recorded in the Fukushima complex.

A short-term, whole-body dose of over 10 sieverts would cause immediate illness and subsequent death within a few weeks, according to the World Nuclear Association.

The Hitachi and Toshiba robots are designed to handle 1,000 sieverts and no robot has yet been disabled due to radiation.

Radiation levels near the fuel are lethal,” said MIT’s Buongiorno, who holds the university’s Tepco chair, a professorship based on an initial donation by the company 10 years ago. There are no formal affiliations or obligations for the faculty who receive the chair, he said.

Because the No. 2 unit is the only one of the three reactors that didn’t experience a hydrogen explosion, there was no release into the atmosphere and radiation levels inside the core are higher compared to the other two units, according to the utility.

No. 3 Unit

Tepco’s balance sheet has been strapped by ballooning Fukushima cleanup costs and slumping national power demand. All of the company’s nuclear power plants remain shut since it halted the No. 6 reactor at its Kashiwazaki Kariwa station in March 2012. The company is seeking drastic changes in top management in consultation with the Japanese government, TV Asahi reported Friday, without attribution.

The utility has focused on removing spent fuel in the upper part of the reactor building, which Toshiba aims to extract with a claw-like system. This fuel didn’t melt and is still in a pool that controls its temperature.

The used-fuel in No. 3 is scheduled to begin removal before the end of the decade, the first among the three reactors that melted down. Toshiba is developing another robot to search for melted fuel, planned to enter sometime in the year ending March 2018. The company hasn’t announced yet the design or strategy.

https://about.bnef.com/blog/race-for-japans-melted-nuclear-fuel-leaves-trail-of-dead-robots/

Operation of communication about the “scorpion” robot which will be sent to the confinement enclosure of reactor n ° 2

TEPCO and its partners launched a communication operation about the “scorpion” robot, which will be sent to the containment reactor of reactor n ° 2 in an attempt to locate the corium, ie the highly radioactive molten fuel, mixed with debris. It is not certain that the mission will be a success, the cleaning robot having lasted only two hours in this enclosure because of the extreme radiations, without being able to finish its task.

A press release announces what we already know and insists on the challenges: “every step is a new challenge for TEPCO, but TEPCo welcomes the challenges”. The company would be almost happy with the accident? It is accompanied by a promotional video with a comparison to the kendô fights posted on its Facebook page.

http://www.tepco.co.jp/en/press/corp-com/release/2017/1377951_10469.html

https://www.facebook.com/OfficialTEPCOen/videos/1346869308705698/

The Japanese nuclear industry wants to place itself on the decommissioning market and highlights the technologies being developed. This robot was designed by IRID, Toshiba and TEPCO. IRID benefits from public funds. As for Toshiba, it is almost bankrupt because of its nuclear branch and TEPCO is financially in a bad shape.

The press release and the video do not provide any relevant information and are in complete discrepancy with reality.

1. Current conditions of Unit 2 Primary Containment Vessel (PCV)

Nuclear fuel in the Primary Containment vessel (PCV) was exposed to the air and melted from the impact of March 2011 Great Earthquake.

As a result of the accident analysis, it was found that a portion of melted nuclear fuel might have been fallen inside the pedestal.

To remove fuel debris, it is necessary to investigate the PCV and clarify the conditions of debris and surrounding structures.

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2. Outline of Unit 2 PCV investigation

[Purpose]: To obtain feedback information (deformation of platform, etc.) for the design and

development of next investigation devices inside the pedestal

To inspect conditions on the platform inside pedestal, fuel debris fallen to the CRD housing, and conditions of structures inside pedestal.

[Investigation point]: Platform and Control Rod Drive (CRD) will be investigated from the platform inside pedestal

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3. Work steps for Unit 2 PCV investigation

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4. Preparatory investigation results from X-6 penetration to CRD rail

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4. Preparatory investigation results at the entrance of pedestal area

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4. Preparatory investigation results of pedestal area

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5. Additional results expected from the self-propelled investigation device

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6. Investigation by the self-propelled investigation device to the end of CRD rail

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6. Investigation by the self-propelled investigation device to the end of CRD rail

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Reference: Investigation results on the platform inside the pedestal

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Technical information for the media is available here:

In Japanese about the upcoming mission http://www.tepco.co.jp/nu/fukushima-np/handouts/2017/images1/handouts_170215_08-j.pdf

And in English http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2017/images/handouts_170215_01-e.pdf

And about radiation protection measures http://www.tepco.co.jp/nu/fukushima-np/handouts/2017/images1/handouts_170215_09-j.pdf

And in English http://www.tepco.co.jp/en/nu/fukushima-np/handouts/2017/images/handouts_170215_02-e.pdf

Translated from L’ACROnique de Fukushima http://fukushima.eu.org/operation-de-communication-sur-le-robot-scorpion-qui-va-etre-envoye-dans-lenceinte-de-confinement-du-reacteur-n2/

HELEN CALDICOTT: The Fukushima nuclear meltdown continues unabated

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Dr Helen Caldicott, explains recent robot photos taken of Fukushima’s Daiichi nuclear reactors: radiation levels have not peaked, but have continued to spill toxic waste into the Pacific Ocean — but it’s only now the damage has been photographed.

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 gaoled 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.

https://independentaustralia.net/politics/politics-display/helen-caldicott-the-fukushima-nuclear-meltdown-continues-unabated,10019

Clean-up robot pulled from Fukushima Reactor 2 due to extremely high radiation

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Cleaner Robot Pulled From Fukushima Reactor Due to Immense Radiation

The camera on the bot was compromised by the high levels of radiation.

A remote-controlled cleaning robot sent into a damaged reactor at Japan’s Fukushima nuclear plant had to be removed Thursday before it completed its work because of camera problems most likely caused by high radiation levels.

It was the first time a robot has entered the chamber inside the Unit 2 reactor since a March 2011 earthquake and tsunami critically damaged the Fukushima Da-ichi nuclear plant.

Tokyo Electric Power Co. said it was trying to inspect and clean a passage before another robot does a fuller examination to assess damage to the structure and its fuel. The second robot, known as the “scorpion,” will also measure radiation and temperatures.

Thursday’s problem underscores the challenges in decommissioning the wrecked nuclear plant. Inadequate cleaning, high radiation and structural damage could limit subsequent probes, and may require more radiation-resistant cameras and other equipment, TEPCO spokesman Takahiro Kimoto said.

“We will further study (Thursday’s) outcome before deciding on the deployment of the scorpion,” he said.

TEPCO needs to know the melted fuel’s exact location and condition and other structural damage in each of the three wrecked reactors to figure out the best and safest ways to remove the fuel. It is part of the decommissioning work, which is expected to take decades.

During Thursday’s cleaning mission, the robot went only part way into a space under the core that TEPCO wants to inspect closely. It crawled down the passage while peeling debris with a scraper and using water spray to blow some debris away. The dark brown deposits grew thicker and harder to remove as the robot went further.

After about two hours, the two cameras on the robot suddenly developed a lot of noise and their images quickly darkened — a sign of a problem caused by high radiation. Operators of the robot pulled it out of the chamber before completely losing control of it.

The outcome means the second robot will encounter more obstacles and have less time than expected for examination on its mission, currently planned for later this month, though Thursday’s results may cause a delay.

Both of the robots are designed to withstand up to 1,000 Sieverts of radiation. The cleaner’s two-hour endurance roughly matches an estimated radiation of 650 Sieverts per hour based on noise analysis of the images transmitted by the robot-mounted cameras. That’s less than one-tenth of the radiation levels inside a running reactor, but still would kill a person almost instantly.

Kimoto said the noise-based radiation analysis of the Unit 2’s condition showed a spike in radioactivity along a connecting bridge used to slide control rods in and out, a sign of a nearby source of high radioactivity, while levels were much lower in areas underneath the core, the opposite of what would normally be the case. He said the results are puzzling and require further analysis.

TEPCO officials said that despite the dangerously high figures, radiation is not leaking outside of the reactor.

Images recently captured from inside the chamber showed damage and structures coated with molten material, possibly mixed with melted nuclear fuel, and part of a disc platform hanging below the core that had been melted through.

http://www.popularmechanics.com/science/energy/a25155/cleaner-robot-pulled-from-fukushima-reactor-due-to-radiation/?src=socialflowTW

 

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Extremely high radiation breaks down Fukushima clean-up robot at damaged nuclear reactor

A clean-up mission using a remotely operated robot at Japan’s crippled Fukushima nuclear plant has had to be aborted, as officials feared they could completely lose control of the probe affected by unexpectedly high levels of radiation.

The robot equipped with a high-pressure water pump and a camera designed to withstand up to 1,000 Sieverts of cumulative exposure had been pulled off the inactive Reactor 2 at the Fukushima Daiichi nuclear complex earlier this week, The Japan Times reported Friday, citing the plant operator, Tokyo Electric Power Company (TEPCO). The device reportedly broke down just two hour into the probe.

The failure led experts to rethink estimated levels of radiation inside the damaged reactor.

While last week TEPCO said it might stand at 530 Sieverts per hour – a dose that can almost instantly kill a human being, following the latest aborted mission a company official has said a reading of up to 600 Sieverts should be “basically correct.”

Even despite the considerable 30-percent margin of error for the revised estimate, the latest probe left no doubt that radiation levels are at record highs within the reactor. Even though it cannot be measured directly with a Geiger counter or dosimeter, the dose is calculated by its effect on the equipment.

Last month, a hole of no less than one square meter in size was discovered beneath the same reactor’s pressure vessel. The apparent opening in the metal grating is believed to have been caused by melted nuclear fuel, TEPCO then said.

The recent mission has demonstrated that the melted fuel is close to the studied area.

 

While extreme radiation levels have been registered within the reactor, officials insist that no leaks or increases outside have been detected.

The failure might force Japan to rethink the robot-based strategy it has adopted for locating melted fuel at Fukushima, according to The Japan Times.

The robot affected by radiation was supposed to wash off thick layers of dirt and other wreckage, clearing ways for another remotely controlled probe to enter the area, tasked with carrying out a more proper investigation to assess the state of the damaged nuclear reactor. Previously, even specially-made robots designed to probe the underwater depths beneath the power plant have crumbled and shut down affected by the radioactive substance inside the reactor.

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The Fukushima Daiichi nuclear power plant suffered a blackout and subsequent failure of its cooling systems in March 2011, when it was hit by an earthquake and tsunami. Three of the plant’s six reactors were hit by meltdowns, making the Fukushima nuclear disaster the worst since the Chernobyl catastrophe in Ukraine in 1986. TEPCO is so far in the early stages of assessing the damage, with the decommissioning of the nuclear facility expected to take decades.

https://www.rt.com/news/377025-fukushima-radiation-breaks-robot/