Finding and removing melted fuel rods at Fukushima No. 1 — Nikkei Asian Review, The Japan Times

Nikkei Asian Review, “Survey fails to find melted rods at Fukushima reactors”:

” TOKYO — A remote survey of the Fukushima Daiichi nuclear plant’s No. 1 reactor was unable to locate and photograph melted nuclear fuel, Tokyo Electric Power Co. Holdings said Thursday, complicating efforts to remove that material as part of an extensive cleanup.

Tepco on Saturday sent a robot equipped with a camera into the containment vessel for the No. 1 unit. The majority of fuel rods have melted through the unit’s pressure vessel since the plant was struck by the March 11, 2011, earthquake and tsunami. The prevailing view has been that those melted fuel rods are now sitting under 2.5m of water at the bottom of the containment vessel.

The plan was to explore the bottom section by dipping a camera into the pool of water for the first time. But unexpected barriers such as pipes kept the camera around 1 meter from the bottom in most of the 10 positions surveyed instead of the intended depth of about 40cm from the bottom. While the camera was able to capture sand-like sediment, there was no trace of the melted fuel rods. Adding a fifth day to the investigation turned up no further evidence.

Yuichi Okamura, acting general manager of Tepco’s onsite nuclear power division, offered few comments at the utility’s Thursday news conference, saying only that “photographs and radiation data will need to be evaluated in conjunction with one another.”

The timeline set by Tepco and the government for decommissioning the Fukushima plant aims to begin extraction of melted-down material from the No. 1, No. 2 or No. 3 reactor in 2021 or earlier. An extraction plan is to be decided this summer. But the fact that the status of the melted rods still remains unknown underscores the seriousness of the accident.

The results of the robot survey were “limited,” according to Masanori Naitoh, director of nuclear safety analysis at the Institute of Applied Energy’s Nuclear Power Engineering Center. “It would be difficult to set a plan for extraction based on the information from this survey alone.”

An investigation of the No. 2 reactor also fell short, with the survey robot unable to reach the targeted spot right under the unit’s pressure vessel. ”

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The Japan Times, “Tepco’s biggest hurdle: How to remove melted fuel from crippled Fukushima reactors”:

” Six years after the triple meltdown at the Fukushima No. 1 nuclear power plant, recent investigations underneath the damaged reactor 2 using cameras and robots came close to identifying melted fuel rods for the first time.

Experts say getting a peek inside the containment vessel of reactor 2 was an accomplishment. But it also highlighted how tough it will be to further pinpoint the exact location of the melted fuel, let alone remove it some time in the future.

The biggest hurdle is the extremely lethal levels of radiation inside the containment vessel that not only prevent humans from getting near but have also crippled robots and other mechanical devices.

Safely removing the melted fuel would be a best-case scenario but the risks and costs should be weighed against the option of leaving the melted fuel in the crippled reactors, some experts said.

“The work to probe inside the containment vessels and remove the fuel debris will be extremely tough because of the high radiation levels,” said Hiroshi Miyano, who heads a panel of the Atomic Energy Society of Japan, which is discussing ways to decommission the Fukushima plant and making recommendations to the government.

The government and Tokyo Electric Power Company Holdings Inc. are trying to find a way to remedy the situation but existing methods and technologies may not be sufficient, Miyano said.

In search of melted fuel

The world’s attention turned to the melted fuel rods in late January when Tepco inserted a 10-meter-plus tube equipped with a camera into the containment vessel of reactor 2 to capture images under the pressure vessel that housed the fuel rods.

The images showed black lumps scattered beneath the pressure vessel.

When the March 11, 2011, Great East Japan Earthquake and monstrous tsunami hit, the plant suffered a blackout and lost its key cooling system, triggering meltdowns in reactors 1, 2 and 3. The melted nuclear fuel rods penetrated the pressure vessels and fell into the containment vessels.

Tepco had put cameras inside the containment vessels several times in the past six years but January’s probe was the first to apparently find melted fuel debris.

“We understand that this is a big milestone. We could finally get to see what it was like underneath the pressure vessel,” said Yuichi Okamura, general manager of Tepco’s nuclear power and plant siting division.

“This is critical information in order to remove the fuel debris.”

Radiation barrier

But Tepco hasn’t confirmed that the black lumps are melted fuel, saying they could be paint or cable wrappings, and further investigation is needed.

Capturing the images may be progress but the robot and camera forays have not provided enough information about how to deal with the melted fuel.

Last month, Tepco sent a remote-controlled, scorpion-shaped robot in to further probe inside the reactor 2 containment vessel. But the robot failed before it reached under the pressure vessel after a tire became stuck.

The robot’s dosimeter measured radiation levels of 210 sieverts per hour — enough to kill humans instantly.

While 210 sieverts per hour indicate the melted fuel was nearby, the radiation crippled the robot’s electronics, including its semiconductors and cameras, indicating that the further use of robots to pinpoint the melted fuel will be difficult, robotics experts said.

There are computer chips “designed to withstand a certain level of radiation, but the level inside the containment vessel is totally different,” said Satoshi Tadokoro, a professor at Tohoku University who is an expert on disasters and rescue robots.

The radiation can damage a robot’s chips that serve as their brains, causing the devices to lose control, said Tadokoro, whose robots have also been used at the Fukushima plant.

“On top of the high level of radiation, the entrance (to the containment vessel) for the robot is very small,” restricting what types of robots can be used to hunt for the melted fuel, he said.

Tepco said the opening it created on the side of the reactor 2 containment vessel is about 11 cm in diameter.

Fuel removal strategy

Tepco is set to conduct internal probes of the reactor 1 containment vessel this month and is preparing similar missions for reactor 3.

The government and utility then plan to adopt a basic fuel removal strategy this summer and fine-tune the plan next year, with the actual fuel removal taking place in or after 2021.

There are essentially three options for the strategy, according to the Tokyo-based International Research Institute for Nuclear Decommissioning (IRID), which is developing technologies for the Fukushima plant decommission.

One option is to flood the containment vessels with water and use a crane above the reactors to hoist up the melted fuel. The second option is to carry out the same process but without water. The third is to install removal equipment through the side of the containment vessel.

There are merits and drawbacks to each option, said Shoji Yamamoto, who heads the team developing technologies to create the fuel removal devices at IRID.

The flooding option can block radiation using water, but if the fuel melts into the water, it could pose a risk of recriticality. The debris may need to be cut into pieces for removal, but this process would enable water to get between multiple pieces, creating the condition for recriticality. For nuclear chain reactions to happen there needs to be a certain distance between nuclear fuel and water.

If there is no water, the recriticality risk is minimal but the massive radiation levels cannot be blocked, Yamamoto said.

Tepco’s Okamura said being able to block radiation with water is a huge plus, but noted the reactor 2 containment vessel had cracks and holes that could let injected coolant water escape.

With the Three Mile Island nuclear accident in the U.S., the flooding option was used to retrieve the melted fuel in the 1980s. But the key difference was that all of the melted fuel stayed inside the pressure vessel, so it was easier to flood the reactor.

Because the melted fuel in reactors 1, 2 and 3 at the Fukushima plant all penetrated the pressure vessels and fell into the containment vessels, extracting it from the top or the side was a tough call, Yamamoto said, noting it was important to know the exact location of the melted fuel.

The distance between the top of the pressure vessel and the bottom of the containment vessel is about 45 meters and some parts inside the pressure vessels will need to be removed if Tepco tries to remove the debris inside the containment vessels from the top.

“If we know that the melted fuel is concentrated in the containment vessels, it will be more efficient to remove it from the side” because the entry point is closer, Yamamoto said.

Whatever option is decided, Yamamoto stressed that maintaining the fuel removal device will be difficult because the radiation will probably cripple it.

“The fuel removal device will be controlled remotely … it will be broken somewhere down the line and the parts will have to be replaced, considering its (ability to withstand) radiation,” he said.

“Given that, maintenance will have to be done remotely, too, and that will be a big challenge.”

To remove or not

Another option altogether is for Tepco to leave the melted fuel where it is.

During a media tour of the Fukushima No. 1 plant last month, Okamura of Tepco said the utility intended to collect the melted fuel because leaving it was “not an appropriate way” to manage nuclear fuel.

Miyano of the Atomic Energy Society of Japan said the debris must be removed because radioactive materials, including nuclear fuel, must be strictly controlled under international rules requiring strict monitoring.

Domestic nuclear power plant operators have to report the amount of nuclear fuel they have to the Nuclear Regulation Authority, which then reports to the International Atomic Energy Agency.

“There is the question of whether the government and Tepco decide not to remove the fuel debris. That would be an international issue,” said Miyano, adding that a consensus from the international community would be needed.

At the same time, Miyano said debate and analysis will be required to decide which choice would be best by looking at various factors, including how much it will cost to pick up all the melted fuel and where to store it. ”

by Kazuaki Nagata

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Fukushima Daiichi decay heat and corium status report — SimplyInfo

Read SimplyInfo’s fantastic summary of all of the studies regarding the movement and behavior of the melted corium in Fukushima Daiichi’s reactors 1, 2, and 3 along with an analysis that provides an estimate of where the melted fuel may be located.

by Dean Wilkie, nuclear engineer
edited by Nancy Foust

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Risk of another Chernobyl or Fukushima type accident plausible, experts say — University of Sussex, Phys.org

” A team of risk experts who have carried out the biggest-ever analysis of nuclear accidents warn that the next disaster on the scale of Chernobyl or Fukushima may happen much sooner than the public realizes.

Researchers at the University of Sussex, in England, and ETH Zurich, in Switzerland, have analysed more than 200 nuclear accidents, and – estimating and controlling for effects of industry responses to previous disasters – provide a grim assessment of the risk of nuclear power.

Their worrying conclusion is that, while nuclear accidents have substantially decreased in frequency, this has been accomplished by the suppression of moderate-to-large events. They estimate that Fukushima- and Chernobyl-scale disasters are still more likely than not once or twice per century, and that accidents on the scale of the 1979 meltdown at Three Mile Island in the USA (a damage cost of about 10 Billion USD) are more likely than not to occur every 10-20 years.

As Dr Spencer Wheatley, the lead author, explains: “We have found that the risk level for nuclear power is extremely high.

“Although we were able to detect the positive impact of the industry responses to accidents such as Three Mile Island and Chernobyl, these did not sufficiently remove the possibility of extreme disasters such as Fukushima. To remove such a possibility would likely require enormous changes to the current fleet of reactors, which is predominantly second-generation technology.”

The studies, published in two papers in the journals Energy Research & Social Science and Risk Analysis, put fresh pressure on the nuclear industry to be more transparent with data on incidents.

“Flawed and woefully incomplete” public data from the nuclear industry is leading to an over-confident attitude to risk, the study warns. The research team points to the fact that their own independent analysis contains three times as much data as that provided publicly by the industry itself. This is probably because the International Atomic Energy Agency, which compiles the reports, has a dual role of regulating the sector and promoting it.

The research team for this new study gathered their data from reports, academic papers, press releases, public documents and newspaper articles. The result is a dataset that is unprecedented – being twice the size of the next largest independent analysis. Further, the authors emphasize that the dataset is an important resource that needs to be continually developed and shared with the public.

Professor Benjamin Sovacool of the Sussex Energy Group at the University of Sussex, who co-authored the studies, says: “Our results are sobering. They suggest that the standard methodology used by the International Atomic Energy Agency to predict accidents and incidents – particularly when focusing on consequences of extreme events – is problematic.

“The next nuclear accident may be much sooner or more severe than the public realizes.”

The team also call for a fundamental rethink of how accidents are rated, arguing that the current method (the discrete seven-point INES scale) is highly imprecise, poorly defined, and often inconsistent.

In their new analysis, the research team provides a cost in US dollars for each incident, taking into account factors such as destruction of property, the cost of emergency response, environmental remediation, evacuation, fines, and insurance claims. And for each death, they added a cost of $6 million, which is the figure used by the US government to calculate the value of a human life.

That new analysis showed that the Fukushima accident in 2011 and the Chernobyl accident in 1986 cost a combined $425 billion – five times the sum of all the other events put together.

However, these two extremes are rated 7 – the maximum severity level – on the INES scale. Fukushima alone would need a score of between 10 and 11 to represent the true magnitude of consequences.

Further, the authors emphasize that such frequency-severity statistical analysis of holistic consequences should be used as a complementary tool to the industry standard Probabilistic Safety Assessment, especially when aggregate consequences are of interest.

Professor Sovacool adds: “The results suggest that catastrophic accidents such as Chernobyl and Fukushima are not relics of the past.

“Even if we introduce new nuclear technology, as long as older facilities remain operational—likely, given recent trends to extend permits and relicense existing reactors—their risks, and the aggregate risk of operating the global nuclear fleet, remain.”

Finally, the authors emphasize that this work is not comparative in nature, i.e. it does not quantify the risks of other energy sources. It provides a risk assessment for nuclear power alone, thus informing a single criterion, for a single power source, in the selection of a portfolio of multiple power sources, where many criteria must be considered.

Fellow co-author Professor Didier Sornette stresses: “While our studies seem damning of the nuclear industry, other considerations and potential for improvement may actually make nuclear energy attractive in the future.”

The 15 most costly nuclear events analysed by the team are:

  1. Chernobyl, Ukraine (1986) – $259 billion
  2. Fukushima, Japan (2011) – $166 billion
  3. Tsuruga, Japan (1995) – $15.5 billion
  4. TMI, Pennsylvania, USA (1979) – $11 billion
  5. Beloyarsk, USSR (1977) – $3.5 billion
  6. Sellafield, UK (1969) – $2.5 billion
  7. Athens, Alabama, USA (1985) – $2.1 billion
  8. Jaslovske Bohunice, Czechoslovakia (1977) – $2 billion
  9. Sellafield, UK (1968) – $1.9 billion
  10. Sellafield, UK (1971) – $1.3 billion
  11. Plymouth, Massachusetts, USA (1986) – $1.2 billion
  12. Chapelcross, UK (1967) – $1.1 billion
  13. Chernobyl, Ukraine (1982) – $1.1 billion
  14. Pickering, Canada (1983) – $1 billion
  15. Sellafield, UK (1973) – $1 billion “

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How the US and Japan see India as ripe for nuclear exploitation — SimplyInfo

This article by SimplyInfo provides a lot of good context for the reasons behind Japan’s push to export nuclear technology in India.

Also read the Catch News article, “Keep your nuclear power, Mr. Shinzo Abe. We can do without a Fukushima.

**Writing the nuclear meltdown playbook — Arnie Gundersen via Fairewinds Energy Education

Arnie Gundersen: ” People today who are familiar with social media think that TMI means “Too Much Information”. But to me, and anyone listening to the news in 1979, TMI will always represent the disaster at Three Mile Island, when the public received too little information, not too much.

At the time of the nuclear disaster at TMI, there were plans to build more than 200 nuclear plants in the US, with some projections topping 1,000. Today, less than 100 nuclear plants are operating in the US. During the 1970’s, the total amount invested in those early plants easily exceeded one trillion dollars. If the public became fearful of nuclear power, then the nuclear industry, investors, and banks that had loaned money would face huge losses, so the nuclear industry and nuclear regulators tried desperately to minimize the significance of what was happening at the crippled reactor.

The pattern of denial created by the nuclear industry during the TMI meltdown had at least five steps in its playbook:

  1. Make it appear that “authorities” have the situation under control.
  2. Delay any evacuation orders for as long as possible.
  3. Claim radiation releases are much lower than they actually are.
  4. Claim radiation exposures are acceptable and that no one will die.
  5. And lastly, minimize conflicting information given to the press through paid off experts.

The formula for damage control at TMI was designed by the nuclear industry composed a one size fits all “playbook” the industry has followed for all nuclear catastrophes since TMI. Comments made during the triple meltdown at Fukushima Daiichi by utility owner Tokyo Electric could easily mimic those made at Chernobyl and TMI! When Maggie and I saw these old tricks being played again at Fukushima Daiichi, we dedicated ourselves to ensuring that the public has an accessible resource on which to rely that provides accurate information, and thus the Fairewinds videos were born.

In this video posted to commemorate the TMI disaster, I discuss the pattern of denial regarding nuclear power plant failures and meltdowns, not just for TMI but also for Chernobyl and Fukushima Daiichi as well. We at Fairewinds Energy Education hope you will watch it and think about sharing the true facts with others. ”

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36 years of three mile island’s lethal lies … and still counting — Harvey Wasserman via Ecowatch

Harvey Wasserman: ” The lies that killed people at Three Mile Island 36 years ago on March 28, 1979 are still being told at Chernobyl, Fukushima, Diablo Canyon, Davis-Besse … and at TMI itself.

As the first major reactor accident that was made known to the public is sadly commemorated, and as the global nuclear industry collapses, let’s count just 36 tip-of-the iceberg ways the nuclear industry’s radioactive legacy continues to fester:

1. When about half of TMI’s fuel melted on March 28, 1979, the owners, industry and regulators all denied it, and continued to deny it until robotic cameras showed otherwise.

2. Early signs that such an accident could happen had already surfaced at the Davis-Besse reactor in Ohio, which was also manufactured by Babcock & Wilcox. TMI’s owners later sued Davis-Besse’s owners for not warning them about what had happened.

3. When TMI’s radiation poured into the atmosphere the industry had (and still has) no idea how much escaped, but denied it was of any significance even though stack monitors failed and dosimeters in the field indicated high releases (plant owners claimed they were “defective”). Only due to the work of the great Dr. Ernest Sternglass, recently departed, was public attention turned to the potential harm this radiation could do.

4. When animals nearby suffered mass mutations and death, the industry denied it. When the plague was confirmed by the Pennsylvania Department of Agriculture and the Baltimore News-American, the industry denied the damage could be related to radiation.

5. Industry “experts” assured the public radiation doses to downwinders were similar to a single x-ray, but ignored well-established findings from Dr. Alice Stewart and others that a single x-ray to a pregnant woman could double the chances of childhood leukemia among her offspring.

6. Industry “experts” ignored the reality that radioactive fallout can come down in clumps rather than spread evenly, and scoffed at findings from neighborhood surveys done by Jane Lee, Mary Osbourne and others showing major outbreaks of cancer in certain downwind neighborhoods.

7. When humans nearby were born with Down’s Syndrome and other mutations, and then adults began dying, the industry denied it, then denied any connection to TMI, but then did pay at least $15 million in out-of-court settlements to affected families on condition they not speak about it in public.

8. When Chernobyl exploded in 1986, Soviet officials said nothing as massive clouds of radiation poured across Europe and into the jet stream that would carry it to the U.S. within 10 days.

9. The U.S. government did nothing of sufficient scale to monitor Chernobyl’s radiation as it came here, and did nothing to warn the public to avoid milk and other foods that might concentrate that radiation, and has repeated that behavior in the wake of Fukushima.

10. A massive bird die-off at the Pt. Reyes National Seashore came with the arrival of the Chernobyl cloud and was documented by resident ornithologist Dr. Dave DeSante, whose findings were ignored by the government; soon thereafter, DeSante lost his job.

11. Chernobyl’s radiation was tracked all across Europe where it continues to irradiate plants, animals and humans. The most credible study of Chernobyl’s human death toll put it at 985,000 in 2010.

12. Chernobyl still seethes with radiation, but the massive, hugely expensive movable sarcophagus meant to cover it is not yet in place.

13. When fire runs through the wooded areas around Chernobyl, massive quantities of radiation are re-released into the atmosphere.

14. Fifteen Soviet-era reactors remain operable in Ukraine, much of which is now a de facto war zone, raising serious doubts about what will happen to them and the rest of the downwind human race.

15. The Japanese government was repeatedly and passionately warned by thousands of citizens for more than 40 years that putting reactors in a tsunami zone surrounded by earthquake faults was not a good idea. They were dismissed as “alarmists” and repeatedly assured that the reactors at Fukushima and elsewhere around Japan could come to no harm.

16. Despite repeated public protests, when Fukushima Dai’ichi was built an 85-foot-high bluff was taken down so units 1 through 4 could operate more cheaply at sea level; as widely predicted, they were massively flooded on March 11, 2011.

17. Critical backup batteries meant to keep the reactor cores cool in case of melt-downs were placed in basements which were thoroughly flooded when the tsunami hit Fukushima. Workers later frantically took batteries from nearby parked cars to try to power up the stricken cooling systems and other critical components.

18. The exact whereabouts of the melted cores from Fukushima Units 1, 2 and 3 remain unknown.

19. After a half-century of industry assurances that American reactors could not explode, four General Electric reactors blew up at Fukushima.

20. By estimate of Hiroaki Koide, assistant professor at Kyoto University Research Reactor Institute, some 30 times as much Cesium 137 has been released at Fukushima as was released during the bombing of Hiroshima.

21. Some 300 tons of radioactive water continues to pour into the Pacific Ocean from Fukushima every day.

22. Thousands of highly radioactive spent fuel rods remain scattered around the Fukushima site; thousands are also still suspended in damaged spent fuel pools 100 feet in the air atop weakened buildings above shattered, melted reactors.

23. A petition signed by more than 150,000 people demanding that Fukushima be taken over by the world community was submitted to the United Nations on November 7, 2013, but has yet to receive a response of any kind.

24. Fukushima is still owned and operated by Tokyo Electric Power, which built it despite massive public opposition and continues to mismanage it while turning the “clean up” into a profit center, with a labor force thoroughly infiltrated by organized crime.

25. Like Fukushima, California’s Diablo Canyon reactors were built despite huge public protests, and sit in a tsunami zone surrounded by earthquake faults whose potential seismic power exceeds Diablo’s structural capacities, according numerous experts, including NRC official Dr. Michael Peck, who worked at Diablo for the commission.

26. A continual stream of revelations indicate illegal collusion on safety and other issues at Diablo between its owners, Pacific Gas & Electric, and the Nuclear Regulatory Commission, as well as the California Public Utilities Commission.

27. Diablo’s owners almost certainly violated regulatory requirements and the law in using components within the reactors that were not tested to meet seismic standards.

28. Earthquakes have already damaged at least two U.S. reactors, at Ohio’s Perry site and at North Anna, Virginia (that quake also damaged the Washington Monument in our nation’s capital).

29. Public money designated for use by PG&E to upgrade piping systems was diverted to executive bonuses, according to the Los Angeles Times. In 2010 unrepaired gas lines, which were known to have been deteriorating for a decade, blew up in San Bruno, killing eight people and doing millions of dollars in damage. Such a disaster at Diablo Canyon could kill countless thousands and do untold damage to the national economy and global ecology.

30. Diablo Canyon’s once-through cooling system violates state and federal water quality regulations by dumping huge quantities of hot, radioactive liquid into the Pacific, killing billions of marine creatures while unbalancing the ocean ecology and contributing to climate chaos.

31. Like most other old U.S. reactors, Ohio’s Davis-Besse is literally crumbling, with the concrete in its safety shield being pulverized by continual freezing, yielding ever-growing holes in the structure.

32. Like most other old U.S. reactors, Diablo Canyon, Davis-Besse, five reactors in Illinois and many more cannot compete in electricity markets against wind power, solar panels, other renewable sources or increased efficiency, and would shut down were it not for massive public subsidies.

33. Ohio’s Public Utilities Commission is being asked by FirstEnergy, Davis-Besse’s owner, for subsidies amounting to more than $3 billion to keep open that decrepit reactor, which opened in 1978, and the Sammis coal burner, which is even older.

34. Wisconsin’s Kewaunee reactor has shut for purely economic reasons despite being fully amortized and having no apparent outstanding maintenance or engineering crises.

35. California’s San Onofre reactors were shut in part due to violations of licensing requirements that are mirrored at both Diablo Canyon and Davis-Besse, where shut-downs could be required by law. Let’s hope …

36. As we commemorate this tragic anniversary, we must note that this list of reactor nightmares could go very very far past 36. But let’s hope it doesn’t take that many more years to realize the folly of this failed technology.

In honor of the many many victims of Three Mile Island, and of the great Dr. Sternglass and so many dedicated experts and activists, we must turn this sad litany into the action needed to shut down ALL the world’s reactors so we don’t have to experience this nightmare yet again.

The lives we save will be our own … and those of our children … and theirs … ”

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