Japan pictures likely show melted Fukushima fuel for first time — Bloomberg

” New images show what is likely to be melted nuclear fuel hanging from inside one of Japan’s wrecked Fukushima reactors, a potential milestone in the cleanup of one of the worst atomic disasters in history.

Tokyo Electric Power Co. Holdings Inc., Japan’s biggest utility, released images on Friday showing a hardened black, grey and orange substance that dripped from the bottom of the No. 3 reactor pressure vessel at Fukushima, which is likely to contain melted fuel, according to Takahiro Kimoto, an official at the company. The company sent a Toshiba-designed robot, which can swim and resembles a submarine, to explore the inside of the reactor for the first time on July 19.

“Never before have we taken such clear pictures of what could be melted fuel,” Kimoto said at a press briefing that began at 9 p.m. Friday in Tokyo, noting that it would take time to analyze and confirm whether it is actually fuel. “We believe that the fuel melted and mixed with the metal directly underneath it. And it is highly likely that we have filmed that on Friday.”

If confirmed, the substance — which has the appearance of icicles — would be the first discovery of the fuel that melted during the triple reactor accident at Fukushima six years ago. For Tokyo Electric, which bears most of the clean-up costs, the discovery would help the utility design a way to remove the highly-radioactive material.

The robot, which is about 30 centimeters (12 inches) long, will search for melted fuel at the bottom of the reactor on Saturday. It is possible that the company will take more pictures of what could be melted fuel spread across the floor and lower levels, according to Tokyo Electric’s Kimoto. Fuel from a nuclear meltdown is known as corium, which is a mixture of the atomic fuel rods and other structural materials.

Early Signs

“It is important to know the exact locations and the physical, chemical, radiological forms of the corium to develop the necessary engineering defueling plans for the safe removal of the radioactive materials,” said Lake Barrett, a former official at the U.S. Nuclear Regulatory Commission who was involved with the cleanup at the Three Mile Island nuclear power plant in the U.S. “The recent investigation results are significant early signs of progress on the long road ahead.”

Because of the high radioactivity levels inside the reactor, only specially designed robots can probe the unit. And the unprecedented nature of the Fukushima disaster means that Tepco, as the utility is known, is pinning its efforts on technology not yet invented to get the melted fuel out of the reactors.

Removal Plans

The company aims to decide on the procedure to remove the melted fuel from each unit as soon as this summer. And it will confirm the procedure for the first reactor during the fiscal year ending March 2019, with fuel removal slated to begin in 2021.

Decommissioning the reactors will cost 8 trillion yen ($72 billion), according to an estimate in December from the Ministry of Economy, Trade and Industry. Removing the fuel is one of the most important steps in a cleanup that may take as long as 40 years.

Similar to the latest findings on Friday, Tepco took photographs in January of what appeared to be black residue covering a grate under the Fukushima Dai-Ichi No. 2 reactor, which was speculated to have been melted fuel. However, a follow-up survey by another Toshiba-designed robot in February failed to confirm the location of any melted fuel in the reactor after it got stuck in debris.

A robot designed by Hitachi-GE Nuclear Energy Ltd. also failed to find any melted fuel during its probe of the No. 1 reactor in March.

The significance of Friday’s finding “might be evidence that the robots used by Tepco can now deal with the higher radiation levels, at least for periods of time that allow them to search parts of the reactor that are more likely to contain fuel debris,” M.V. Ramana, professor at the Liu Institute for Global Issues at the University of British Columbia, said by email.

“If some of these fragments can be brought out of the reactor and studied, it would allow nuclear engineers and scientists to better model what happened during the accident.” ”

by Stephen Stapczynski, Bloomberg

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Fukushima clean-up chief still hunting for 600 tonnes of melted radioactive fuel — Mark Willacy, ABC

” The operator of the stricken Fukushima nuclear plant has revealed that 600 tonnes of reactor fuel melted during the disaster, and that the exact location of the highly radioactive blobs remains a mystery.

 In an exclusive interview with Foreign Correspondent, the Tokyo Electric Power Company’s chief of decommissioning at Fukushima, Naohiro Masuda, said the company hoped to pinpoint the position of the fuel and begin removing it from 2021.

But he admitted the technology needed to remove the fuel has to be invented.

“Once we can find out the condition of the melted fuel and identify its location, I believe we can develop the necessary tools to retrieve it,” Mr Masuda said.

“So it’s important to find it as soon as possible.”

Clean-up to take decades, cost tens of billions of dollars

Reactors 1, 2 and 3 at the Fukushima Dai-ichi nuclear plant suffered catastrophic meltdowns in the hours and days after a giant tsunami swamped the facility on 11 March, 2011.

Thousands of workers are braving elevated radiation levels to stabilise and decommission the plant.

TEPCO says the process will take 30 to 40 years and tens of billions of dollars.

“In Reactor 1, all of the fuel has melted down from inside the pressure vessel,” Mr Masuda said.

“In reactors 2 and 3, about 30 per cent to 50 per cent remains in the pressure vessel and the rest has melted down. But unfortunately, we don’t know exactly where [the fuel] is.”

The head of the United States Nuclear Regulatory Commission (NRC) at the time of the meltdowns at Fukushima doubts the fuel can be retrieved, saying such an operation has never been done before.

“Nobody really knows where the fuel is at this point and this fuel is still very radioactive and will be for a long time,” said Gregory Jaczko in an interview with Foreign Correspondent in Washington.

“It may be possible that we’re never able to remove the fuel. You may just have to wind up leaving it there and somehow entomb it as it is.”

Radiation killing search robots inside reactor

For the first time, TEPCO has revealed just how much of the mostly uranium fuel melted down after the tsunami swamped the plant.

“It’s estimated that approximately 200 tonnes of debris lies within each unit,” said TEPCO’s Naohiro Masuda.

“So in total, about 600 tonnes of melted debris fuel and a mixture of concrete and other metals are likely to be there.”

TEPCO has attempted to use custom-built robots to access high-dose radiation parts of the reactor buildings where humans cannot go.

“All the robots have been disabled, the instrumentation, the camera … have been disabled because of the high radiation fields,” former NRC boss Gregory Jaczko said.

Appointed to head the US nuclear watchdog by President Barack Obama in 2009, Dr Jaczko resigned a year after the Fukushima disaster.

A particle physicist, he now questions the safety of nuclear power.

“You have to now accept that in all nuclear power plants, wherever they are in the world … that you can have this kind of a very catastrophic accident and you can release a significant amount of radiation and have a decade long clean-up effort on your hands,” he said.

10 million bags of contaminated soil in gigantic waste dumps

Another supporter turned opponent of nuclear power is Naoto Kan, who was the Japanese prime minister at the time of the Fukushima meltdowns.

He says those who argue that nuclear power is a safe, cheap source of energy are misguided.

“So far, the government is paying $70 billion to support TEPCO,” Mr Kan said.

“But that is not enough. It will probably cost more than $240 billion. I think 40 years [to decommission the plant] is an optimistic view.”

More than 100,000 Japanese are still unable to return home because their communities lie in elevated radiation zones.

Some people have returned to their towns and villages since the completion of decontamination work, which often involves the removal of up to 15 centimetres of topsoil from fields and from around homes.

More than 10 million large bags of contaminated soil and waste have so far been collected. The bags are now stored in thousands of sites around Fukushima, with some of the piles several storeys high.

“In order for people to come back, we need to show that the Fukushima plant is in a stable condition,” Naohiro Masuda said.

“We need to make that the situation … we’re working on something [for] which there is no textbook.” ”

by Mark Willacy

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