Fukushima’s underground ice wall keeps nuclear radiation at bay — CNET

” The intricate network of small metal pipes, capped off by six-foot-high metal scaffolding, shouldn’t stand out amid the numerous pieces of industrial equipment littered throughout the Fukushima Daiichi Nuclear Power Plant. After all, it’s a power plant.

I take a closer look, and notice spheres of ice perched upon the smaller pipes, which line the center of the structure. The facility sits at the water’s edge, and there’s a brisk breeze blowing through.

But not that brisk.

It turns out, coolant is running through the pipes, freezing the soil below and creating an impermeable ice wall that’s nearly 100 feet deep and a mile long, encircling the reactors.

It’s like a smaller-scale subterranean version of the Wall in Game of Thrones, but instead of keeping out White Walkers and wights, this line of defense keeps in a far more realistic danger: radioactive contaminants from melted-down reactors that threaten to spill into the water by Fukushima Daiichi.

Daiichi is the site of the worst nuclear disaster, which happened after an earthquake hit on March 11, 2011, triggering a tsunami that devastated the facility. Two 50-foot-high waves knocked out the power generators that were keeping three of the six reactors’ fuel rods cool, triggering explosions and meltdowns that forced more than 160,000 people to flee their homes. Many of them still haven’t returned.

I came to Fukushima to check out the robots tasked with the near-impossible task of cleaning up Fukushima Daiichi. While here, I encountered this underground wall of ice.

The structure, which cost roughly $300 million, paid for by public funds, serves as critical protection, defending the Fukushima area from one of the most radioactive hotspots in the world. While Tokyo Electric Power Co., also known as Tepco, struggles to find a way to remove radioactive material from the facility – a process the government estimates could take more than four decades – the more immediate concern is what to do with the contaminated water leaking out from the facility.

One of the solutions has been to put up (down?) this underground ice wall, which prevents much of the surrounding groundwater from getting in. And while the practice of freezing soil to create a barrier has been around for more than 150 years, the magnitude of the application that stands before me is quite literally groundbreaking.

“Nobody has taken on a project of this scale,” Hideki Yagi, general manager of Tepco’s Nuclear Power Communications Unit, tells me through an interpreter.

Ice cold

While the term “ice wall” has a colorful ring to it, engineers use the more academic-sounding term Artificial Ground Freezing. The technique came out of France in 1862 as a way to help with the construction of mine shafts before German engineer F.H. Poetsch patented it. Since then, it’s been used to aid in building underwater tunnels or vertical shafts, as well as to cut off groundwater or redirect contaminated materials.

At Fukushima, my eyes follow the path of the pipes, which stretch around the reactor building. A Tepco employee tells me that a calcium chloride solution is pumped down through a smaller inner pipe, and circulated back up a large outer pipe.

The coolant brings down the temperature of each pipe to -30 degrees Celsius, or -22 degrees Fahrenheit, and the pipes are spaced about three feet apart. The cold emanating from each one hardens the soil around it.

The point of the ice wall is to keep the groundwater that runs down from the mountains to the west from entering Fukushima Daiichi and mixing with the toxic water leaking out of the Unit 1, 2 and 3 reactors. That is,  keep the clean water on the outside of the wall, while the contaminated water stays inside.

Tepco and manufacturing partners, such as Toshiba and Mitsubishi, are working on robots to identify and determine how to clear out the radioactive materials in each of the reactors’ primary containment vessels, essentially the heart of each facility.

Until then, they need a way to slow or stop the flow of water into the facility. At least initially, Tepco wasn’t even sure if the project was feasible.

“One of the challenges was how they would inject the pipes into the earth at such a deep level without impacting the other operations around it, and whether it would work,” Yagi says.

With the wall in place, Tepco says it has been able to reduce the level of contaminated water generated from Daiichi. But a Reuters report in March 2018 found that the wall still let a fair amount of clean water in, adding to the volume of toxic water the company needs to deal with. Tepco, however, says it’s been effective in reducing the volume.

“We know this is not the end of our effort,” says a company spokesman. “We will be continuously working hard to reduce the amount of  generation of contaminated water.”

The leaky bucket

Imagine a leaky bucket that constantly needs to be filled with water. At the same time, the water from the leak needs to be collected and stored. And there’s no end in sight to this cycle.

That essentially is the problem that Tepco faces at Daiichi. The fuel rods stored in the three radioactive units constantly have to be cooled with fresh water, but leaks mean the company needs to be vigilant about keeping the tainted liquid from getting out of the facility’s grounds.

Since the accident nearly eight years ago, Tepco has collected 1.1 million tons of contaminated water in 900 tanks stored on the grounds at Daiichi. The company estimates it has enough space in the 37.7-million-square-foot facility to house an additional 270,000 tons of water, which means it would run out sometime in 2020.

“We’re conscious of the fact that we can’t keep storing more and more water,” Kenji Abe, a spokesman for Tepco’s decommissioning and decontamination unit, says through an interpreter.

Tepco has worked on several solutions to decrease the level of contaminated water generated by the facility. The company has switched from tanks sealed with bolts to welded tanks, which offer greater storage capacity and less risk of leaks. There’s a steel wall by the water to keep the contaminants from flowing into the ocean. Tepco has also covered 96 percent of the surface of most of the facility with concrete, preventing rainwater from seeping in.

Then there’s the ice wall, which has done its share of lowering the amount of contaminated water generated from the facility by keeping out most of the groundwater.

Over the past three and a half years, Tepco has seen the amount of polluted water generated fall by a quarter to just under 3,900 cubic feet of water per day, with occasional spikes during periods of rainfall.

The final element

I’m in full protective gear, including a Tyvek coverall, hardhat and full-face respirator mask, walking through one of three water treatment facilities at Daiichi. I move hastily, trying to keep up with my Tepco guides, when my suit gets snagged on an exposed bolt.

Did the suit rip? My eyes shoot back at my photographer and widen with fear. This is usually the part in an outbreak movie that dooms a key character. I look down and see the suit is still intact, and breathe a sigh of relief.

It turns out, I didn’t need to panic. The facility, called the Advanced Liquid Processing System, isn’t radioactive, although it’s designed to remove radioactive elements from the collected water. There are three such facilities, which can process a total of 70,630 cubic feet of water a day.

So far, treatment technology from partner companies like Kurion and Sarry have enabled Tepco to remove 62 of the 63 radioactive elements from the water, but one, tritium, remains.

It’s this one element, which is bonded to the water at an atomic level, that means Tepco needs to keep collecting and storing the water.

Lake Barrett, a senior adviser to Tepco who previously served as acting director of the Office of Civilian Radioactive Waste Management at the US Department of Energy, notes that reactors in China and Canada already discharge water with tritium.

“It’s fundamentally safe,” Barrett says.

But organizations such as Greenpeace have called for Tepco to keep storing the water, noting that much of the early batches of treated water far exceed safety limits for radioactive elements.

Given the sensitivities around Fukushima, Tepco must continue to store the water. A spokesman said the company isn’t planning to disperse the water. But it is one option being considered by the Japanese government, which ultimately makes the decision.

“Resolving the issue of the contaminated water is something we haven’t yet reached a final solution on,” Yagi says.

Analyzing the data

Underneath the building housing the restaurant and employee rest area is a water treatment analysis center, a super-clean area that requires us to go through numerous radiation tests and four sets of boot changes.

There are glass beakers containing sea water, groundwater and water from the ALPS facilities. Scientists walk around in silence, moving beakers from one machine to another. A dozen machines in a second room measure the gamma ray levels.

The facility was originally built underground in 2014 because it needed to be on the Daiichi site, but couldn’t be exposed to radiation because of the nature of the tests. The walls are 8 inches thick, with the more sensitive labs hardened with an additional 20 inches. The facility has grown by 16 times over the past four years as it expanded the number of workers and machines.

“No other facility in Japan can handle the amount of data and work we do here,” says a Tepco scientist working at the facility who preferred not to identify himself.

He adds that all of the data is released publicly. “That’s because society demands work with a high level of trust,” he says.

The scientist explains that Japan has set a legal radioactivity limit of 60,000 becquerel per liter of tritium. But the treated water is still at 1.7 million Bq per liter, or roughly 30 times what’s deemed safe.

So, for now, Tepco must continue collecting the water. And the ice wall continues to stand, invisible to onlookers, as one of the most important lines of defense. ”

by Roger Cheng, CNET

source with photos and a video showing how robots have been used to view melted fuel

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Local Fury and Health Concerns as Japan plans to dump a million tons of radioactive Fukushima water into ocean — Common Dreams

” In a move that has sparked outrage from local residents and dire health warnings from environmentalists, the Japanese government is reportedly planning to release 1.09 million tons of water from the Fukushima Dai-ichi nuclear plant into the Pacific Ocean despite evidence that it contains “radioactive material well above legally permitted levels.”

While both the Japanese government and Tokyo Electric Power Co. (Tepco)—the company that runs the Fukushima Dai-ichi plant—have claimed that radioactive material in the water has been reduced to undetectable amounts and that only “safe levels of tritium” remain, documents obtained by the London-based Telegraph suggest that the cleaning system being used to decontaminate the water “has consistently failed to eliminate a cocktail of other radioactive elements, including iodine, ruthenium, rhodium, antimony, tellurium, cobalt, and strontium.”

“The government is running out of space to store contaminated water that has come into contact with fuel that escaped from three nuclear reactors after the plant was destroyed in the March 2011 earthquake and tsunami that struck northeast Japan,” the Telegraph reported. “Its plan to release the approximately 1.09 million tons of water currently stored in 900 tanks into the Pacific has triggered a fierce backlash from local residents and environmental organizations, as well as groups in South Korea and Taiwan fearful that radioactivity from the second-worst nuclear disaster in history might wash up on their shores.”

One document the Telegraph obtained from the government body charged with responding to the 2011 Fukushima disaster reportedly indicates that the Japanese government is perfectly aware that the Advanced Liquid Processing System (ALPS) is failing to eliminate radioactive materials from the water stored at the Fukushima site, despite its claims to the contrary.

Last September, the Telegraph notes, “Tepco was forced to admit that around 80 percent of the water stored at the Fukushima site still contains radioactive substances above legal levels after the Ministry of Economy, Trade, and Industry held public hearings in Tokyo and Fukushima at which local residents and fishermen protested against the plans.”

Shaun Burnie, a nuclear specialist with Greenpeace, argued that even so-called “safe” levels of tritium are harmful to humans and marine life.

“Its beta particles inside the human body are more harmful than most X-rays and gamma rays,” Burnie told the Telegraph, adding that there “are major uncertainties over the long-term effects posed by radioactive tritium that is absorbed by marine life and, through the food chain, humans.”

The Japanese government’s reported plans to release the water into the Pacific despite these warnings “cannot be considered an action without risk to the marine environment and human health,” Burnie concluded. ”

by Jake Johnson, Common Dreams

source

Stop sending women & children back to Fukushima fallout zone, UN expert tells Japan — RT

” A UN human rights expert has urged Japan to reconsider its policy of returning women and children to areas still high in radiation after they were displaced by the Fukushima meltdown.

Baskut Tuncak, the UN’s special rapporteur on hazardous substances, criticized the Japanese government’s decision to resettle citizens in areas with radiation levels above one millisievert per year, the threshold of health risk to groups particularly sensitive to radiation, including children and women of childbearing age.

“The gradual lifting of evacuation orders has created enormous strains on people whose lives have already been affected by the worst nuclear disaster of this century,” he said.

Tuncak presented his findings to a General Assembly committee meeting in New York. “Many feel they are being forced to return to areas that are unsafe, including those with radiation levels above what the government previously considered safe,” he added in a news release.

The Japanese government dismissed his concerns, blaming one-sided information and expressing concern that the statement could stoke “unnecessary fears” about the site of the March 2011 nuclear disaster.

After the earthquake and subsequent power plant meltdown, the Japanese government raised its acceptable radiation levels to 20 millisieverts. The UN last year issued a recommendation to return the level to pre-meltdown standards, but Japan ignored the request.

Over seven years later, radiation levels around Fukushima remain high, as has the apparent level of denial within the Japanese government. They recently announced plans to release about a million tons of wastewater contaminated with radioactive elements into the Pacific Ocean, claiming high-tech processing had reduced the contaminants to safe levels, but was forced to admit that 80 percent of the water remained contaminated after local residents protested the dumping plans.

The government has been removing evacuation orders gradually and plans to repeal all of them within five years, regardless of the contamination level in the areas. Japan was slow to enact the evacuation orders initially – only residents within a 3km radius of the meltdown were told to evacuate immediately after the accident, and four days later, residents 30km away were still being told to shelter in place. However, it was already allowing resettlement in areas within 20km of the plant by 2014.

Tuncak has clashed with the Japanese government before. In August, he and two other UN human rights experts criticized them for putting at risk the lives of those involved in the Fukushima clean-up. An earlier UN report showed that 167 plant workers had received radiation doses that increased their cancer risk.

Only last month did the Japanese government admit that even a single plant worker had died as a result of radiation exposure. The unnamed man, whose job included measuring radiation levels immediately after the meltdown, was exposed to about 195 millisieverts of radiation and developed lung cancer after leaving his job in 2015. ”

by RT

source

Fukushima’a other big problem: A Million tons of radioactive water — Wired

” The tsunami-driven seawater that engulfed Japan’s Fukushima Daiichi nuclear plant has long since receded. But plant officials are still struggling to cope with another dangerous flood: the enormous amounts of radioactive water the crippled facility generates each day. More than 1 million tons of radiation-laced water is already being kept on-site in an ever-expanding forest of hundreds of hulking steel tanks—and so far, there’s no plan to deal with them.

The earthquake and tsunami that hammered Fukushima on March 11, 2011 triggered meltdowns in three of its six reactors. That left messes of intensely radioactive fuel somewhere loose in the reactor buildings—though no one knows exactly where. What is known, however, is that every day, as much as much as 150 tons of groundwater percolates into the reactors through cracks in their foundations, becoming contaminated with radioactive isotopes in the process.

To keep that water from leaking into the ground or the Pacific, Tepco, the giant utility that owns the plant, pumps it out and runs it through a massive filtering system housed in a building the size of a small aircraft hangar. Inside are arrays of seven-foot tall stainless steel tubes, filled with sand grain-like particles that perform a process called ion exchange. The particles grab on to ions of cesium, strontium, and other dangerous isotopes in the water, making room for them by spitting out sodium. The highly toxic sludge created as a byproduct is stored elsewhere on the site in thousands of sealed canisters.

This technology has improved since the catastrophe. The first filtering systems, installed just weeks after the disaster by California-based Kurion Inc. (which has since been bought by Veolia, a French resource management company), only caught cesium, a strong gamma radiation emitter that makes it the most dangerous of the isotopes in the water. The tubes in those arrays were filled with highly modified grains of naturally occurring volcanic minerals called zeolites. By 2013, the company developed entirely artificial particles—a form of titano silicate—that also grab strontium.

The filters, however, don’t catch tritium, a radioactive isotope of hydrogen. That’s a much trickier task. Cesium and strontium atoms go into solution with the water, like sugar in tea; but tritium can bond with oxygen just like regular hydrogen, rendering the water molecules themselves radioactive. “It’s one thing to separate cesium from water, but how do you separate water from water?” asks John Raymont, Kurion’s founder and now president of Veolia’s nuclear solutions group. The company claims to have developed a system that can do the job, but Tepco has so far balked at the multi-billion dollar cost.

So for now, the tritiated water is pumped into a steadily growing collection of tanks. There are already hundreds of them, and Tepco has to start building a new one every four days.

Tepco has at least reduced the water’s inflow. As much as 400 tons per day was gushing in just a couple of years ago. In an effort to keep the groundwater from getting in, Tepco has built a network of pumps, and in 2016 installed an underground “ice wall”—a $300 million subterranean fence of 30-yard-long rods through which tons of sub-zero brine is pumped, freezing the surrounding earth. All of which helps, but hasn’t solved the problem.

Tritium is far less dangerous than cesium—it emits a weaker, lower-energy form of radiation. Still, all that tritiated water can’t just be stored indefinitely. “Some of those tanks and pipes will eventually fail. It’s inevitable,” says Dale Klein, a former head of the US Nuclear Regulatory Commission who has been consulting with Tepco since the early days following the disaster. (In fact, hundreds of tons of water leaked out of the tanks in 2013 and 2014, sparking an international outcry. Tepco has since improved their design.)

Klein, among others, believes that the concentrations of tritium are low enough that the water can safely be released into the sea. “They should dilute and dispose of it,” he says. “It would be better to have a controlled release than an accidental one.”

But the notion of dumping tons of radioactive water into the ocean is understandably a tough sell. Whatever faith the Japanese public had left in Tepco took a further beating in the first couple of years after the meltdowns, when several investigations forced the company to acknowledge they had underreported the amount of radiation released during and after the disaster. Japan’s fishing industry raises a ruckus whenever the idea of dumping the tritiated water is broached; they already have to contend with import restrictions imposed by neighboring countries worried about eating contaminated fish. Japan’s neighbors including China, Korea, and Taiwan have also objected.

For now, all Tepco can do is keep building tanks, and hope that someone comes up with a solution before they run out of room—or the next earthquake hits. “

by Vince Beiser, Wired

source with internal links and photo

Move over Chernobyl, Fukushima is now officially the worst nuclear power disaster in history — CounterPunch

” The radiation dispersed into the environment by the three reactor meltdowns at Fukushima-Daiichi in Japan has exceeded that of the April 26, 1986 Chernobyl catastrophe, so we may stop calling it the “second worst” nuclear power disaster in history. Total atmospheric releases from Fukushima are estimated to be between 5.6 and 8.1 times that of Chernobyl, according to the 2013 World Nuclear Industry Status Report. Professor Komei Hosokawa, who wrote the report’s Fukushima section, told London’s Channel 4 News then, “Almost every day new things happen, and there is no sign that they will control the situation in the next few months or years.”

Tokyo Electric Power Co. has estimated that about 900 peta-becquerels have spewed from Fukushima, and the updated 2016 TORCH Report estimates that Chernobyl dispersed 110 peta-becquerels. (A Becquerel is one atomic disintegration per second. The “peta-becquerel” is a quadrillion, or a thousand trillion Becquerels.)

Chernobyl’s reactor No. 4 in Ukraine suffered several explosions, blew apart and burned for 40 days, sending clouds of radioactive materials high into the atmosphere, and spreading fallout across the whole of the Northern Hemisphere — depositing cesium-137 in Minnesota’s milk.

The likelihood of similar or worse reactor disasters was estimated by James Asselstine of the Nuclear Regulatory Commission (NRC), who testified to Congress in 1986: “We can expect to see a core meltdown accident within the next 20 years, and it … could result in off-site releases of radiation … as large as or larger than the releases … at Chernobyl. Fukushima-Daiichi came 25 years later.

Contamination of soil, vegetation and water is so widespread in Japan that evacuating all the at-risk populations could collapse the economy, much as Chernobyl did to the former Soviet Union. For this reason, the Japanese government standard for decontaminating soil there is far less stringent than the standard used in Ukraine after Chernobyl.

Fukushima’s Cesium-137 Release Tops Chernobyl’s

The Korea Atomic Energy Research (KAER) Institute outside of Seoul reported in July 2014 that Fukushima-Daiichi’s three reactor meltdowns may have emitted two to four times as much cesium-137 as the reactor catastrophe at Chernobyl.

To determine its estimate of the cesium-137 that was released into the environment from Fukushima, the Cesium-137 release fraction (4% to the atmosphere, 16% to the ocean) was multiplied by the cesium-137 inventory in the uranium fuel inside the three melted reactors (760 to 820 quadrillion Becquerel, or Bq), with these results:

Ocean release of cesium-137 from Fukushima (the worst ever recorded): 121.6 to 131.2 quadrillion Becquerel (16% x 760 to 820 quadrillion Bq). Atmospheric release of Cesium-137 from Fukushima: 30.4 to 32.8 quadrillion Becquerel (4% x 760 to 820 quadrillion Bq).

Total release of Cesium-137 to the environment from Fukushima: 152 to 164 quadrillion Becquerel. Total release of Cesium-137 into the environment from Chernobyl: between 70 and 110 quadrillion Bq.

The Fukushima-Daiichi reactors’ estimated inventory of 760 to 820 quadrillion Bq (petabecquerels) of Cesium-137 used by the KAER Institute is significantly lower than the US Department of Energy’s estimate of 1,300 quadrillion Bq. It is possible the Korean institute’s estimates of radioactive releases are low.

In Chernobyl, 30 years after its explosions and fire, what the Wall St. Journal last year called “the $2.45 billion shelter implementation plan” was finally completed in November 2016. A huge metal cover was moved into place over the wreckage of the reactor and its crumbling, hastily erected cement tomb. The giant new cover is 350 feet high, and engineers say it should last 100 years — far short of the 250,000-year radiation hazard underneath.

The first cover was going to work for a century too, but by 1996 was riddled with cracks and in danger of collapsing. Designers went to work then engineering a cover-for-the-cover, and after 20 years of work, the smoking radioactive waste monstrosity of Chernobyl has a new “tin chapeau.” But with extreme weather, tornadoes, earth tremors, corrosion and radiation-induced embrittlement it could need replacing about 2,500 times. ”

by John LaForge, CounterPunch

source with article sources listed at the bottom of the page

Fukushima nuclear plant: Tsunami wall could have avoided disaster but boss scrapped the plan, employee testifies — Newsweek

” A worker for the plant involved the 2011 Fukushima nuclear disaster said in a Japanese court Wednesday that his former boss was warned that a massive tsunami could strike the site, but delayed measures to build a protective wall to prevent it.

An unnamed employee of the Tokyo Electric Power Company (TEPCO) that owns the ruined Fukushima Daiichi or No.1, Nuclear Power Plant testified during a trial this week that a 2008 safety test showed an earthquake could cause a tsunami as high as 52 feet capable of pounding the coastal facility, according to The Asahi Shimbun. The company was initially set to build a seawall, but the employee told the court that former TEPCO Vice President Sakae Muto suddenly dismissed the idea.

The potentially catastrophic scenario was brought up again during a meeting on March 7, 2011, compelling shocked regulators to again recommend a wall to shield the facility, The Japan Times reported. But it was too late already: A magnitude 9.0 earthquake and tsunami struck only four days later on March 11, 2011, leaving up to 18,500 people dead or missing and destroying the facility.

Three out of the six nuclear reactors at the Fukushima No.1 plant suffered devastating meltdowns. Muto, along with former TEPCO Chairman Tsunehisa Katsumata and former TEPCO Vice President Ichiro Takekuro were indicted in February 2016 and are facing trial for suspected professional negligence resulting in death or injury after the worst nuclear disaster since the Chernobyl incident in 1986.

The multi-billion dollar effort to recover the site is far past schedule and over budget, but the TEPCO has claimed some recent successes. Six years after the disaster, the melted nuclear fuel was finally founded at the bottom of the partially submerged reactors. The site was so radioactive, even the robots previously sent it could not traverse the deadly core.

Efforts to retrieve the fuel, however, have been hampered as the $324 million ice wall that penetrated 100 feet into the earth failed to stop groundwater from leaking into the site, as Reuters reported last month. In fact, the amount of groundwater seeping into the facility may have increased since the highly-anticipated ice wall was installed last August, amounting to the latest setback in a cleanup process already beset by seemingly endless complications and miscalculations.

Removing this water adds to an already growing storage crisis on the site. TEPCO deliberately added water to cool off the plant’s damaged reactors. After coming in contact with the plant, the coolant water and groundwater became tainted with a substance known as tritium, a byproduct of the nuclear process notoriously difficult to filter out of water. TEPCO has accumulated over 1 million tons of this tritium-laced water in 650 giant tanks, according to The Japan Times, and is urging the government to let the company begin dumping it into the ocean.

Some locals have protested this, however. While tritium was a natural byproduct of the nuclear process that experts have described as harmless in smaller doses and was dumped into oceans worldwide, Fukushima activists and fishermen have argued that dumping tritium, even in small quantities, would further hurt the reputation of the region, still synonymous with nuclear disaster. Nearby China and South Korea are among the nations that still restrict the import of certain products from Japan.

Lingering concerns about radiation have also reportedly kept many of the 160,000 residents that fled Fukushima from returning. Life, nevertheless, has begun to return to some parts of the crisis-stricken prefecture. The town of Okuma announced Wednesday that some citizens would be allowed to stay overnight starting next week for the first time since the March 2011 disaster, Japanese daily The Mainichi Shimbun said. ”

by Tom O’Connor, Newsweek

source with image and internal links