Six years after Fukushima, much of Japan has lost faith in nuclear power — The Conversation

” Six years have passed since the Fukushima nuclear disaster on March 11, 2011, but Japan is still dealing with its impacts. Decommissioning the damaged Fukushima Daiichi nuclear plant poses unprecedented technical challenges. More than 100,000 people were evacuated but only about 13 percent have returned home, although the government has announced that it is safe to return to some evacuation zones.

In late 2016 the government estimated total costs from the nuclear accident at about 22 trillion yen, or about US$188 billion – approximately twice as high as its previous estimate. The government is developing a plan under which consumers and citizens will bear some of those costs through higher electric rates, taxes or both.

The Japanese public has lost faith in nuclear safety regulation, and a majority favors phasing out nuclear power. However, Japan’s current energy policy assumes nuclear power will play a role. To move forward, Japan needs to find a new way of making decisions about its energy future.

Uncertainty over nuclear power

When the earthquake and tsunami struck in 2011, Japan had 54 operating nuclear reactors which produced about one-third of its electricity supply. After the meltdowns at Fukushima, Japanese utilities shut down their 50 intact reactors one by one. In 2012 then-Prime Minister Yoshihiko Noda’s government announced that it would try to phase out all nuclear power by 2040, after existing plants reached the end of their 40-year licensed operating lives.

Now, however, Prime Minister Shinzo Abe, who took office at the end of 2012, says that Japan “cannot do without” nuclear power. Three reactors have started back up under new standards issued by Japan’s Nuclear Regulation Authority, which was created in 2012 to regulate nuclear safety. One was shut down again due to legal challenges by citizens groups. Another 21 restart applications are under review.

In April 2014 the government released its first post-Fukushima strategic energy plan, which called for keeping some nuclear plants as baseload power sources – stations that run consistently around the clock. The plan did not rule out building new nuclear plants. The Ministry of Economy, Trade and Industry (METI), which is responsible for national energy policy, published a long-term plan in 2015 which suggested that nuclear power should produce 20 to 22 percent of Japan’s electricity by 2030.

Meanwhile, thanks mainly to strong energy conservation efforts and increased energy efficiency, total electricity demand has been falling since 2011. There has been no power shortage even without nuclear power plants. The price of electricity rose by more than 20 percent in 2012 and 2013, but then stabilized and even declined slightly as consumers reduced fossil fuel use.

Japan’s Basic Energy Law requires the government to release a strategic energy plan every three years, so debate over the new plan is expected to start sometime this year.

Public mistrust

The most serious challenge that policymakers and the nuclear industry face in Japan is a loss of public trust, which remains low six years after the meltdowns. In a 2015 poll by the pro-nuclear Japan Atomic Energy Relations Organization, 47.9 percent of respondents said that nuclear energy should be abolished gradually and 14.8 percent said that it should be abolished immediately. Only 10.1 percent said that the use of nuclear energy should be maintained, and a mere 1.7 percent said that it should be increased.

Another survey by the newspaper Asahi Shimbun in 2016 was even more negative. Fifty-seven percent of the public opposed restarting existing nuclear power plants even if they satisfied new regulatory standards, and 73 percent supported a phaseout of nuclear power, with 14 percent advocating an immediate shutdown of all nuclear plants.

Who should pay to clean up Fukushima?

METI’s 22 trillion yen estimate for total damages from the Fukushima meltdowns is equivalent to about one-fifth of Japan’s annual general accounting budget. About 40 percent of this sum will cover decommissioning the crippled nuclear reactors. Compensation expenses account for another 40 percent, and the remainder will pay for decontaminating affected areas for residents.

Under a special financing scheme enacted after the Fukushima disaster, Tepco, the utility responsible for the accident, is expected to pay cleanup costs, aided by favorable government-backed financing. However, with cost estimates rising, the government has proposed to have Tepco bear roughly 70 percent of the cost, with other electricity companies contributing about 20 percent and the government – that is, taxpayers – paying about 10 percent.

This decision has generated criticism both from experts and consumers. In a December 2016 poll by the business newspaper Nihon Keizai Shimbun, one-third of respondents (the largest group) said that Tepco should bear all costs and no additional charges should be added to electricity rates. Without greater transparency and accountability, the government will have trouble convincing the public to share in cleanup costs.

Other nuclear burdens: Spent fuel and separated plutonium

Japanese nuclear operators and governments also must find safe and secure ways to manage growing stockpiles of irradiated nuclear fuel and weapon-usable separated plutonium.

At the end of 2016 Japan had 14,000 tons of spent nuclear fuel stored at nuclear power plants, filling about 70 percent of its onsite storage capacity. Government policy calls for reprocessing spent fuel to recover its plutonium and uranium content. But the fuel storage pool at Rokkasho, Japan’s only commercial reprocessing plant, is nearly full, and a planned interim storage facility at Mutsu has not started up yet.

The best option would be to move spent fuel to dry cask storage, which withstood the earthquake and tsunami at the Fukushima Daiichi nuclear plant. Dry cask storage is widely used in many countries, but Japan currently has it at only a few nuclear sites. In my view, increasing this capacity and finding a candidate site for final disposal of spent fuel are urgent priorities.

Japan also has nearly 48 tons of separated plutonium, of which 10.8 tons are stored in Japan and 37.1 tons are in France and the United Kingdom. Just one ton of separated plutonium is enough material to make more than 120 crude nuclear weapons.

Many countries have expressed concerns about Japan’s plans to store plutonium and use it in nuclear fuel. Some, such as China, worry that Japan could use the material to quickly produce nuclear weapons.

Now, when Japan has only two reactors operating and its future nuclear capacity is uncertain, there is less rationale than ever to continue separating plutonium. Maintaining this policy could increase security concerns and regional tensions, and might spur a “plutonium race” in the region.

As a close observer of Japanese nuclear policy decisions from both inside and outside of the government, I know that change in this sector does not happen quickly. But in my view, the Abe government should consider fundamental shifts in nuclear energy policy to recover public trust. Staying on the current path may undermine Japan’s economic and political security. The top priority should be to initiate a national debate and a comprehensive assessment of Japan’s nuclear policy. ”

by The Conversation

source with graphics and internal links

Fukushima Bill — Asia Times

” Six years after Japan’s Fukushima nuclear accident three global nuclear corporations are fighting for their very survival.

The bankruptcy filing by Westinghouse Electric Co. and its parent company Toshiba Corp. preparing to post losses of ¥1 trillion (US$9 billion), is a defining moment in the global decline of the nuclear power industry.

However, whereas the final financial meltdown of Westinghouse and Toshiba will likely be measured in a few tens of billions of dollars, those losses are but a fraction of what Tokyo Electric Power Co. (Tepco) is looking at as a result of the Fukushima nuclear disaster.

If the latest estimates for the cost of cleaning up the Fukushima plant prove accurate, Tepco faces the equivalent of a Toshiba meltdown every year until 2087.

In November 2016, the Japanese Government announced a revised estimate for the Fukushima nuclear accident (decommissioning, decontamination, waste management and compensation) of ¥21.5 trillion (US$193 billion) – a doubling of their estimate in 2013.

But the credibility of the government’s numbers have been questioned all along, given that the actual ‘decommissioning’ of the Fukushima plant and its three melted reactors is entering into an engineering unknown.

This questioning was borne out by the November doubling of cost estimates after only several years into the accident, when there is every prospect Tepco will be cleaning up Fukushima well into next century.

And sure enough, a new assessment published in early March from the Japan Institute for Economic Research, estimates that total costs for decommissioning, decontamination and compensation as a result of the Fukushima atomic disaster could range between ¥50-70 trillion (US$449-628 billion).

Rather than admit that the Fukushima accident is effectively the end of Tepco as a nuclear generating company, the outline of a restructuring plan was announced last week.

Tepco Holdings, the entity established to manage the destroyed nuclear site, and the Nuclear Damage Compensation and Decommissioning Facilitation Corporation (NDF) are seeking ways to sustain the utility in the years ahead, confronted as they are with escalating Fukushima costs and electricity market reform.

The NDF, originally established by the Government in 2011 to oversee compensation payments and to secure electricity supply, had its scope broadened in 2014 to oversee decommissioning of the Fukushima Daiichi plant on the Pacific Ocean coast north of Tokyo.

The latest restructuring plan is intended to find a way forward for Tepco by securing a future for its nuclear, transmission and distribution businesses. If possible in combination with other energy companies in Japan.

But the plan, already received less than warmly by other utilities rightly concerned at being burdened with Tepco’s liabilities, is premised on Fukushima cost estimates of ¥21.5 trillion — not ¥50-70 trillion.

To date Tepco’s Fukushima costs have been covered by interest-free government loans, with ¥6 trillion (US$57 billion) already paid out. Since 2012 Tepco’s electricity ratepayers have paid ¥2.4 trillion to cover nuclear-related costs, including the Fukushima accident site.

That is nothing compared to the costs looming over future decades and beyond and it comes at a time when Tepco and other electric utilities are under commercial pressure as never before.

The commercial pressure comes from electricity market reform that since April 2016 allowed consumers to switch from the monopoly utilities to independent power providers.

Prior to the deregulation of the retail electricity market, Tepco had 22 million customers. As the Tepco president observed late last year “The number (of customers leaving Tepco) is changing every day as the liberalization continues … We will of course need to think of ways to counter that competition.”

Countering that competition shouldn’t mean rigging the market, yet Tepco and the other utilities intend to try and retain their decades long dominance of electricity by retaining control over access to the grid. This is a concerted push back against the growth of renewable energy.

Current plans to open the grid to competition in 2020, so called legal unbundling, are essential to wrest control from the big utilities.

The message of unbundling and independence, however, doesn’t seem to have reached the Ministry of Economy, Trade and Industry (METI) that oversees the electricity industry.

Current plans would allow Tepco to establish separate legal entities: Tepco Fuel & Power (thermal power generation), Tepco Energy Partner (power distribution) and Tepco Power Grid (power transmission).

Tepco Holdings will retain their stock and control their management, meaning the same monopoly will retain control of the grid. Where Tepco leads, the other nine electric utilities are aiming to follow.

Leaving the grid effectively still under the control of the traditional utilities will throw up a major obstacle to large scale expansion of renewable energy sources from new companies.

Such businesses will be ‘curtailed’ or stopped from supplying electricity to the grid when the large utilities decide it’s necessary, justified for example to maintain the stability of the grid.

The fact that ‘curtailment’ will be permitted in many regions without financial compensation piles further pain onto new entrants to the electricity market, and by extension consumers.

Further, METI plans to spread the escalating costs of Fukushima so that other utilities and new power companies pay a proportion of compensation costs. METI’s justification for charging customers of new energy companies is that they benefited from nuclear power before the market opened up.

The need to find someone else to pay for Tepco’s mess is underscored by the breakdown of the Fukushima disaster cost estimate in November.

When put at ¥22 trillion estimate, ¥16 trillion is supposed to be covered by Tepco. The Ministry of Finance is to offer ¥2 trillion for decontamination, and the remaining ¥4 trillion is to be provided by other power companies and new electricity providers.

The question is how does Tepco cover its share of the costs when it’s losing customers and its only remaining nuclear plant in Japan, Kashiwazaki Kariwa (the worlds largest), has no prospect of restarting operation due to local opposition?

What happens when Fukushima costs rise to the levels projected of ¥50-70 trillion?

The policy measures being put in place by Tepco, other utilities and the government suggests that they know what is coming and their solution for paying for the world’s most costly industrial accident will be sticking both hands into the public purse. ”

by Shaun Burnie, Asia Times

source

Fukushima cleanup chief urges better use of probe robot — The Seattle Times

” 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.

A robot sent inside the Unit 2 containment vessel last month could not reach as close to the core area as was hoped for because it was blocked by deposits, believed to be a mixture of melted fuel and broken pieces of structures inside. Naohiro Masuda, president of Fukushima Dai-ichi Decommissioning, said he wants another probe sent in before deciding on methods to remove the reactor’s debris.

Unit 2 is one of the Fukushima reactors that melted down following the 2011 earthquake and tsunami.

The plant’s operator, Tokyo Electric Power Co., 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. Probes must rely on remote-controlled robots because radiation levels are too high for humans to survive.

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.

Earlier probes have suggested worse-than-anticipated challenges for the plant’s cleanup, which is expected to take decades. During the Unit 2 probe in early February, the “scorpion” robot crawler stalled after its total radiation exposure reached its limit in two hours, one-fifth of what was anticipated.

“We should think out of the box so we can examine the bottom of the core and how melted fuel debris spread out,” Masuda told reporters.

Probes are also 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.

Cleanup of communities outside of the plant is also a challenge. The cost has reportedly almost doubled to 4 trillion yen ($35 billion) from an earlier estimate. On Thursday, police arrested an Environment Ministry employee for allegedly taking bribes from a local construction firm president, media reports said. ”

by Mari Yamaguchi, The Associated Press

source

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

Helen Caldicott sums up the situation here:

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

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

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

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

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

But there is more to fear.

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

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

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

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

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

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

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

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

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

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

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

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

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

by Helen Caldicott

source

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

by Torrey Bailey

source

Cleaner robot pulled from Fukushima reactor due to radiation — Beloit Daily News

” TOKYO (AP) — 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. ”

by Mari Yamaguchi

source with photos