Tepco admits success of Fukushima ice wall still unknown — The Japan Times

” Tokyo Electric Power Holdings Inc. and the government bet big on an underground ice wall as a key measure to battle the tainted water issue at the crippled Fukushima No. 1 nuclear plant.

But whether the ¥35 billion gambit funded by the government is working to block the inflow of groundwater remains unclear even six months after the utility started freezing an area of underground soil.

Tepco said it needs more time to judge whether the system is working. But the Nuclear Regulation Authority, Japan’s nuclear watchdog, appears skeptical on the effectiveness of the 1.5-km-long wall that encircles reactor buildings 1 to 4, asking Tepco to deal with the issue but without counting on it.

So far Tepco has finished freezing the east side of the ice wall — albeit with delays caused by severe typhoon-driven rains — and 95 percent of the west side but has yet to get the NRA’s approval to freeze the rest of it.

“It’s really unfortunate and I am very sorry” for not being able to provide an assessment of the ice wall, Naohiro Masuda, who heads Tepco’s decommissioning project, told a news conference Thursday.

Masuda said in August that Tepco would be able to provide an assessment of the effectiveness of the ice wall in September, and that the utility would have finished freezing the east side by then.

But Masuda said unexpected heavy rain during recent typhoons melted some parts of the structure.

Masuda said workers have since repaired the damage and finished freezing the east side 100 percent. But he declined to say when the assessment will be released.

The purpose of the ice wall is to block groundwater before it can enter the reactor buildings, which are located between nearby mountains and the ocean.

To do this, Tepco pumps groundwater that has flowed west to east toward five wells near the ocean, back into the reactors to cool them.

If the wall succeeds, the water being pumped from the ocean wells should reduce to about 70 tons each day, from hundreds of tons, according to Tepco. The daily level was between 600-1,200 tons in September, which Tepco attributed to heavy rains.

About 180 tons of groundwater a day seeps into the reactor buildings through cracks or holes and is mixed with contaminated water inside, causing the amount of tainted water at the plant to increase daily.

Currently, about 68,000 tons of tainted water is stored there but the risk remains that it could leak if another powerful quake hits near the facility.

For Tepco, the success of the ice wall is fundamental to achieve its next major goal of removing the contaminated water flooding the basement floors of the reactor buildings.

The utility plans to remove the water by 2020, but believes it can speed up the process by two years if the underground wall works.

The NRA, however, remains unconvinced.

“(Tepco) needs to come up with measures that do not rely on the ice wall and complete the removal of the tainted water from the building by 2020,” Toyoshi Fuketa, deputy NRA chairman, told Tepco officials at a panel meeting Wednesday.

During the meeting, Tepco expressed its intention to freeze the entire west side of the wall.

But Fuketa said, “That’s out of discussion,” since it was still unclear whether the east side was effectively blocking groundwater.

Among the NRA’s concerns is that completely blocking the groundwater on the west side might reduce the groundwater level below the tainted flooded water line in the reactor buildings, which would allow tainted water to leak out.

But as the wall appears to have done little to reduce the amount of groundwater pumped daily, the NRA ordered Tepco to come up with alternative measures.

The NRA has suggested that Tepco strengthen the pumping capability of wells around the reactor buildings to collect the groundwater before it can seep inside.

Tepco said at the Wednesday meeting that it will still be able to finish the removal of tainted water in the buildings by 2020 without the ice wall. ”

by Kazuaki Nagata

source

Japan’s ‘ice wall’ a problematic sticking plaster at Fukushima — The Nation

” Three years ago, Japanese Prime Minister Shinzo Abe helped Tokyo win its bid to host the 2020 Olympics by declaring that the situation at the crisis-wracked Fukushima Daiichi Nuclear Power Station was under control.

That has turned out to be not quite true.

Japan has yet to resolve a crisis at the plant that has lingered since its 2011 nuclear disaster: Groundwater has continued to flow into the basement of the highly contaminated facility. Even worse, some of that has then flown back into the Pacific Ocean.

The problem has hindered a decommission process that was already set to take decades.

In order to reduce the flow, Tokyo has built a huge underground ice wall around reactor buildings. But the 1.5-kilometre-long and 30-metre-deep barrier has not fully frozen, even though it was supposed to become operational around July. The unprecedented project cost taxpayers about 35 billion yen (Bt11.9 billion).

“They have kept saying they can. But they can’t,” former prime minister Junichiro Koizumi told a recent news conference.

Abe’s “under control” remark was “a lie”, Koizumi said. “I’m just wondering how he can say such a thing.”

The phrase “ice wall” is a bit of a misnomer. Officially called the Land-side Impermeable Wall, the coolant-filled barrier will consist of a layer of soil kept frozen by underground pipes, surrounding reactors 1 to 4.

The ice wall project “has stayed on track”, said Tasuhiro Yamagishi, a spokesman for operator Tokyo Electric Power. He added 99 per cent of the wall closest to the sea has been frozen.

The operator, however, acknowledged this month that rainfall from recent typhoons caused melting at two sections of the ice wall in mid-August, leading toxic water to leak from around the plant.

Nonetheless, no contaminated water flowed into the sea, the operator said.

Such statements have not convinced Hisataka Yamazaki, a member of the Tokyo-based Depleted Uranium Centre Japan.

He says he believed there was some leakage, saying the incident was “very serious”.

“As the Fukushima area was not hard-hit by the storms, the incident gave rise to fears that even heavier rain could cause more melting, allowing more toxic water to flow into the nearby Pacific Ocean,” Yamazaki said.

“At this moment, we are looking into the matter and considering what is the best way” to avoid a recurrence, Yamagishi said.

“We know that temporary measures would not work,” said Hideyuki Ban, co-director at Citizens’ Nuclear Information Centre in Tokyo.

“I believe we can say the project has failed.”

In June 2014, the operator started to install equipment for the wall at the plant and completed the work in February. It started to freeze the dirt at the end of March.

“From the beginning, there was doubt whether the wall could be fully frozen,” Ban said.

The water crisis could prolong the decommissioning period, he added.

The Fukushima plant suffered meltdowns at three of its six reactors after a tsunami swept through the complex in March 2011. The operator continues to inject water into the three reactors to keep them cool.

About 100,000 residents have yet to return to their homes near the plant due to radiation contamination.

Koizumi said Japan’s worst nuclear accident led him to revisit nuclear energy issues and came to realise that what experts said about nuclear energy being safe, cheap and clean was “all lies”.

I was ashamed of having believed such lies,” said Koizumi, who served as premier between 2001 and 2006.

Koizumi, who is now an anti-nuclear campaigner, said: “While Tokyo Electric and other power companies are saying they give the highest priority to safety, they actually place priority on profits and put safety on the back-burner.” “

by Takehiko Kambayashi

source

Ice Wall at Fukushima Daiichi damaged by recent typhoons in Japan — Enformable

” Tokyo Electric Power Company (TEPCO) has announced that the “ice wall” (formally known as the “Land-Side Impermeable Wall”) under construction at the crippled Fukushima Daiichi nuclear power plant in Japan has been critically affected by rainfall from recent typhoons that have melted parts of the ice structure, allowing new pathways for highly contaminated water to leak from the basements of the reactor buildings.

The “ice wall” is an underground wall of frozen dirt 100 feet deep and nearly a mile long designed by the utility to divert groundwater from entering the reactor buildings and mixing with the contaminated water therein.  The ice wall was built by installing 100 foot-long pipes into the ground at three-foot intervals and filling them with a supercooled brine solution.  The Japanese utility has had to admit that the $335 million wall of frozen soil and water is not working as designed.

TEPCO announced that contaminated water was able to escape from the reactor buildings through the gaps in the ice wall that had melted from the rainfall and likely reached the Pacific Ocean.

Tokyo Electric will attempt to repair the melted portions of the ice wall by adding additional refrigerant into the underground pipes.

TEPCO has had to repeatedly address issues with the ice wall project, including an announcement in the spring of 2016 that one of the sections had not yet fully frozen.

Experts have warned that the ice wall, being electrically powered, is just as susceptible to damage from natural disasters as the nuclear power plant itself.

“The plan to block groundwater with a frozen wall of earth is failing. They need to come up with another solution, even if they keep going forward with the plant,” said Yoshinori Kitsutaka, a professor of engineering at Tokyo Metropolitan University. ”

by Enformable

source

AP Interview: Fukushima plant’s new ice wall not watertight — AP via ABC News

” Coping with the vast amounts of ground water flowing into the broken Fukushima nuclear plant — which then becomes radiated and seeps back out — has become such a problem that Japan is building a 35 billion yen ($312 million) “ice wall” into the earth around it.

But even if the frozen barrier built with taxpayers’ money works as envisioned, it won’t completely block all water from reaching the damaged reactors because of gaps in the wall and rainfall, creating as much as 50 tons of contaminated water each day, said Yuichi Okamura, a chief architect of the massive project.

“It’s not zero,” Okamura said of the amount of water reaching the reactors in an interview with The Associated Press earlier this week. He is a general manager at Tokyo Electric Power Co., or TEPCO, which operates the facility that melted down after it was hit by a tsunami in 2011, prompting 150,000 people to evacuate.

Workers have rigged pipes that constantly spray water into the reactors to keep the nuclear debris inside from overheating, but coping with what to do with the resulting radiated water has been a major headache. So far, the company has stored the water in nearly 1,000 huge tanks around the plant, with more being built each week.

TEPCO resorted to devising the 1.5-kilometer (1-mile)-long ice wall around the facility after it became clear it had to do something drastic to stem the flow of groundwater into the facility’s basement and keep contaminated water from flowing back out.

“It’s a vicious cycle, like a cat-and-mouse game,” Okamura said of the water-related issues. “We have come up against many unexpected problems.”

The water woes are just part of the many obstacles involved in controlling and dismantling the Fukushima Dai-chi plant, a huge task that will take 40 years. No one has even seen the nuclear debris. Robots are being created to capture images of the debris. The radiation is so high no human being can do that job.

The ice wall, built by construction company Kajima Corp., is being turned on in sections for tests, and the entire freezing process will take eight months since it was first switched on in late March. The entire wall requires as much electricity as would power 13,000 Japanese households.

Edward Yarmak, president of Arctic Foundations, based in Anchorage, Alaska, which designs and installs ground freezing systems and made an ice wall for the Oak Ridge reactor site, says the solution should work at Fukushima.

“The refrigeration system has just been turned on, and it takes time to form the wall. First, the soil freezes concentrically around the pipes and when the frozen cylinders are large enough, they coalesce and form a continuous wall. After time, the wall increases in thickness,” he said in an email.

But critics say the problem of the groundwater reaching the reactors was a no-brainer that should have been projected.

Building a concrete wall into the hill near the plant right after the disaster would have minimized the contaminated water problem considerably, says Shigeaki Tsunoyama, honorary professor and former president of University of Aizu in Fukushima.

Even at the reduced amount of 50 tons a day, the contaminated water produced at Fukushima will equal what came out of Three Mile Island’s total in just eight months because of the prevalence of groundwater in Fukushima, he said.

Although TEPCO has set 2020 as the goal for ending the water problems, Tsunoyama believes that’s too optimistic.

“The groundwater coming up from below can never become zero,” he said in a telephone interview. “There is no perfect answer.”

Okamura acknowledged the option to build a barrier in the higher elevation near the plant was considered in the early days after the disaster. But he defended his company’s actions.

The priority was on preventing contaminated water from escaping into the Pacific Ocean, he said. Various walls were built along the coastline, and radiation monitors show leaks have tapered off over the last five years.

Opponents of nuclear power say the ice wall is a waste of taxpayers’ money and that it may not work.

“From the perspective of regular people, we have serious questions about this piece of research that’s awarded a construction giant,” says Kanna Mitsuta, director of ecology group Friends of the Earth Japan. “Our reaction is: Why an ice wall?” ”

by Yuri Kageyama and Mari Yamaguchi

source

‘Ice wall’ is Japan’s last-ditch effort to contain Fukushima radiation — Huffpost Green; NHK World video

Huffpost Green:

” • The nearly mile-long structure consists of underground pipes designed to form a frozen barrier around the crippled reactors.
• The $312 million system was completed last month, more than a year behind schedule.
• Nearly 800,000 tons of radioactive water are already being stored onsite.

Japanese authorities have activated a large subterranean “ice wall” in a desperate attempt to stop radiation that’s been leaking from the Fukushima Daiichi nuclear power plant for five years.

The wall consists of a series of underground refrigeration pipes meant to form a frozen soil barrier around the four reactors that were crippled during the 2011 Tohoku earthquake and tsunami.

Construction of the $312 million government-funded structure was completed last month, more than a year behind schedule, the Associated Press reports. The nearly mile-long barrier is intended to block groundwater from entering the facility and becoming contaminated.

Tokyo Electric Power Co., or TEPCO, which owns the plant, activated the system Thursday, a day after obtaining approval from Japan’s Nuclear Regulation Authority.

In a video detailing the ice wall’s design, TEPCO said the technology has been successfully used to prevent water intrusion during the construction of tunnels, but this is the first time it has been used to block water from entering a nuclear facility.

“We will create an impermeable barrier,” the company said, “by freezing the soil itself all the way down to the bedrock that exists below the plant. When groundwater flowing downhill reaches this frozen barrier it will flow around the reactor buildings, reaching the sea just as it always has, but without contacting the contaminated water within the reactor buildings.”

TEPCO says the ice wall will be activated in stages over the next several months and is one of several measures the company is taking to reduce the amount of water being contaminated on the site.

Nearly 800,000 tons of radioactive water are already being stored in more than 1,000 industrial tanks at the nuclear plant, according to the AP.

While hopes are high that the ice wall will prove successful in stopping additional radioactive water from seeping into the Pacific Ocean, Shunichi Tanaka, chairman of the Nuclear Regulation Authority, urged caution.

“It would be best to think that natural phenomena don’t work the way you would expect,” he told reporters Wednesday, according to the AP report.

The activation of the ice wall comes just weeks after a TEPCO official reported that robots designed to access the dangerous interior of the plant and seek out the melted fuel rods were “dying” from the high levels of radiation. ”

by Chris D’Angelo

source with photos and several videos explaining how the ice wall works and showing Tepco workers initiating the frozen barrier

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Here is also a good video by NHK World that shows the spatial layout of the ice wall and how it works.