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Fukushima nuclear plant owner apologizes for still-radioactive water

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TOKYO (Reuters) – The owner of the Fukushima nuclear plant, destroyed by an earthquake and tsunami more than seven years ago, said water treated at the site still contains radioactive materials that for years it has insisted had been removed.
 
Storage tanks for contaminated water are seen through a window of a building at Tokyo Electric Power Co.’s (TEPCO) Fukushima Daiichi nuclear power plant in Okuma, Fukushima, Japan, February 23, 2017.
 
The admission by Tokyo Electric Power (Tepco) could ruin its chances of releasing the water into the ocean, a move the nuclear regulator says is safe but which local fishermen oppose.
Tokyo won the bid to host the 2020 Summer Olympics more than five years ago, with Prime Minister Shinzo Abe declaring that Fukushima was “under control” in his final pitch to the International Olympic Committee.
The nearly one million tonnes of stored water at the wrecked plant, enough to fill about 500 Olympic swimming pools, still contained detectable levels of potentially harmful radioactive particles, Tepco told a government committee on Oct. 1.
Tepco apologized to the committee under the Ministry of Economy, Trade and Industry, which is looking into ways to dispose of the water.
A spokesman at Tepco confirmed the findings and the apology.
 
A 9.0-magnitude quake and tsunami in March 2011 triggered meltdowns at three of the Fukushima Daiichi plant’s six reactors, spewing radiation into the air, soil and ocean and forcing 160,000 residents to flee, many of whom have not returned.
It was the world’s worst nuclear disaster since Chernobyl 25 years earlier.
Hundreds of deaths have been attributed to the chaos of evacuations during the crisis and to the hardship and trauma refugees have experienced since then, but the government only last month acknowledged for the first time that one worker at the plant had died from radiation exposure.
Documents on the government committee’s website show that of 890,000 tonnes of water held at Fukushima, 750,000 tonnes, or 84 percent, contain higher concentrations of radioactive materials than legal limits allow.
In 65,000 tonnes of treated water, the levels of radioactive materials are more than 100 times government safety levels.
Radioactive readings of one of those isotopes, strontium-90, considered dangerous to human health, were detected at 600,000 becquerels per liter in some tanks, 20,000 times the legal limit.
Tepco has for years insisted that its purification processes remove strontium and 61 other radioactive elements from the contaminated water but leaves tritium, a mildly radioactive element that is difficult to separate from water.
 
Tritium is regularly released after dilution in normally operating nuclear plants.
“We will filter the water in the tanks one more time to bring the levels to below regulatory limits before release into the ocean if a decision is made to do so,” the Tepco spokesman said.
The water build-up has come about because Tepco must pour water over the three reactors to keep the melted uranium fuel at a safe temperature.
Groundwater flowing from the hills above the plant enters the reactor basements, where it mixes with highly radioactive debris. That gets pumped out and treated before being stored in tanks that are fast filling up.
And a costly “ice wall” is failing to keep groundwater from entering the basements, a Reuters analysis of the Tepco data showed earlier this year.
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The groundwater seepage has delayed Tepco’s clean-up and may undermine the entire decommissioning process.
Nearby residents, particularly fishermen, oppose ocean releases of the treated water because they fear it will keep consumers from buying Fukushima products.
Many countries, including South Korea and China, still have restrictions on produce from Fukushima and neighboring areas.
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October 12, 2018 Posted by | Fukushima 2018 | , , | Leave a comment

Fukushima ice wall yields limited benefit for its cost

March 11, 2018
$322m barrier is less effective than lower-tech measures in fighting contamination
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Tepco has surrounded the reactors at its Fukushima Daiichi plant with a wall of frozen earth.
TOKYO — Tokyo Electric Power Co. Holdings faces the question of whether the so-called frozen soil wall built to contain contamination at its damaged Fukushima Daiichi nuclear power plant justifies its high cost.
The 1.5km barrier of frozen earth, which cost 34.5 billion yen ($322 million) to build using taxpayer money, is supposed to keep groundwater out of the plant’s four reactor buildings. Multiple reactors suffered core meltdowns following the earthquake and tsunami in March 2011. Any water that enters must undergo decontamination, though it is not possible to remove all the radioactive material the water takes up.
Tepco, as the utility is widely known, has said that the barrier has reduced the amount of new contaminated groundwater by 95 tons a day. This suggests that the wall accounts for just one-quarter of recent reductions: Around 110 tons of groundwater were contaminated daily in the three months through February, compared to roughly 490 tons daily before the frozen barrier was created. Freezing of earth around the buildings began in March 2016, and was nearly complete last November.
The utility has said a variety of external factors make those numbers difficult to compare directly, and it plans to release a more detailed analysis as soon as next week. “The frozen soil wall is working,” said Naohiro Masuda, chief decommissioning officer for the Fukushima plant. Some of the tanks to store contaminated water are rendered unnecessary, and “this is huge in monetary terms,” he said.
Others beg to differ. “It is hard to believe” the barrier is “contributing as much as it cost to build,” said Masashi Kamon, professor emeritus at Kyoto University. Japan’s Nuclear Regulation Authority has also raised questions about the barrier’s effectiveness relative to its cost.
Lower-tech measures also in place to prevent contamination, such as wells that pump water out of the ground surrounding the plant, have proven more effective than the frozen barrier. But Tepco plans to keep the wall in place, at an annual cost of more than 1 billion yen, until the groundwater contamination problem is resolved.

March 15, 2018 Posted by | Fukushima 2018 | , | Leave a comment

Fukushima Ice Wall Failing, Water Seepage Into Nuclear Reactors Still A Problem

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March 9th, 2018 by James Ayre

The “ice wall” that Tokyo Electric Power Co (Tepco) put in place a few years ago, with the intent of stopping water seepage into the basements of the Fukushima Dai-ichi nuclear plant, isn’t functioning as advertised (so to speak).
 
Going on an analysis performed by Reuters (using Tepco data), since the ice wall became “operational” — towards the end of August 2017 — an “average of 141 metric tonnes a day of water has seeped into the reactor and turbine areas.”
 
What that means is that after the ice wall was deemed to be fully operational that the flow of groundwater into the areas in question actually increased — as the previous 9 months (before August 2017) had seen an average of 132 metric tonnes a day of groundwater seepage.
 
Considering how expensive the ice wall was to put into place, and Tepco’s assurances to skeptics that the approach would be effective, this is very notable, to say the least.
 
As a result of this failure, large quantities of groundwater are continuing to flow into the basements of the Fukushima nuclear power plants, and there mingle with the extremely radioactive material present there.
 
Arguments are of course being made by Tepco officials, though, that since groundwater flows have lessened over the last few years that the ice wall is working (in conjunction with various pumps and drains), but considering the figures discussed above, effectiveness is certainly limited.
 
The company is claiming that, based on computer models, the ice wall is reducing groundwater flow into the reactors by around 95 tonnes a day, compared to 2 years ago.
 
Reuters provides more information:
 
“The groundwater seepage has delayed Tepco’s clean-up at the site and may undermine the entire decommissioning process for the plant, which was battered by a tsunami 7 years ago this Sunday. Waves knocked out power and triggered meltdowns at 3 of the site’s 6 reactors that spewed radiation, forcing 160,000 residents to flee, many of whom have not returned to this once-fertile coast.
 
“Though called an ice wall, Tepco has attempted to create something more like a frozen soil barrier. Using ¥34.5 billion ($324 million) in public funds, Tepco sunk about 1,500 tubes filled with brine to a depth of 30 meters (100 feet) in a 1.5-kilometre (1-mile) perimeter around 4 of the plant’s reactors. It then cools the brine to minus 30° Celsius (minus 22° Fahrenheit). The aim is to freeze the soil into a solid mass that blocks groundwater flowing from the hills west of the plant to the coast.”
 
It should be realized that the more groundwater seepage there is into the areas in question, the more radioactive water there is to eventually deal with — or not deal with, as may be the case.
 
To date, the radioactive water at the Fukushima site has either been lost to the wider environment or is stored in large tanks at the facility. These storage tanks now total more than a thousand, and store over 1 million tonnes of radioactive water. Tepco has warned that it will run out of space at the site to store this water by as soon as early 2021. What happens then?
 
“I believe the ice wall was ‘oversold’ in that it would solve all the release and storage concerns,” commented Dale Klein, the former head of the US Nuclear Regulatory Commission, and the head of an external committee that’s advising Tepco on safety issues, to Reuters.
 
“The hydrology of the Fukushima site is very complicated and thus the exact water flow is hard to predict, especially during heavy rains.”
 
This reality was made especially clear last October when a typhoon affected the region, and 866 tonnes a day of groundwater flowed into the nuclear reactors for the duration.
 
The Reuters coverage provides a bit more:
 
“However, a government-commissioned panel on Wednesday offered a mixed assessment of the ice wall, saying it was partially effective but more steps were needed…In addition to the building costs, the ice wall needs an estimated 44 million kilowatt hours of electricity a year to run, enough to power about 15,000 typical Japanese homes.
 
“Meanwhile, Tepco must decide how to cope with the growing volume of water stored on site. The purification process removes 62 radioactive elements from the contaminated water but it leaves tritium, a mildly radioactive element that is difficult to separate from water. Not considered harmful in low doses, tritium is released into oceans and rivers by nuclear plants around the world at various national standard levels.
 
“But local residents, particularly fishermen, oppose ocean releases because they fear it will keep consumers from buying Fukushima products. Many countries, including South Korea and China, still have restrictions on produce from Fukushima and neighboring areas.”
 
That’s not to say that such releases won’t be the eventual outcome, as they are one of the primary options now being considered by a government-commissioned task force working on the problem.
 
As far as whether the water in question actually does “only” contain radioactive tritium, that remains an open question as Tepco has yet to allow third-party testing of the store “purified” water in question. Without third-party testing, who actually knows what’s in it?
 
As a reminder here, the Fukushima nuclear disaster effectively began 7 years ago on Sunday and is quite obviously still ongoing. A vast amount of money has already been spent working to contain the nuclear material and contamination at the Fukushima site, but the reality remains that a vast amount more will have to be spent over the coming decades. The area itself will effectively remain unfit for human habitation indefinitely regardless of containment and remediation work.
 

March 14, 2018 Posted by | Fukushima 2018 | , | Leave a comment

Fukushima’s giant ice wall fails to stop water leaking into radioactive area

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March 8, 2018
A giant ice wall constructed underneath the ill-fated Fukushima Daiichi power plant in Japan is failing to prevent groundwater from seeping into it, according to a new report from Reuters.
 
The failure to contain the water is preventing clean-up teams from removing the last of the dangerous radioactive fuel, seven years after a tsunami hit the plant and triggered a catastrophic meltdown.
 
The refrigeration structure, which resembles giant ice lollies, was completed in 2016 and was an attempt to limit the amount of radioactive water created by the incident.
 
The aim is to freeze the soil into a solid mass that blocks groundwater flowing from the hills west of the plant to the coast.
 
At the time of the ice wall construction, nearly 800,000 tonnes of contaminated water was being stored in 1,000 huge industrial tanks at the site.
 
Data released from operator Tokyo Electric Power Co (TEPCO) showed that water leakage has actually got worse since the structure was turned on.
 
An average of 141 metric tonnes of water per day seeped into the reactor and turbine areas, compared to an average of 132 metric tonnes a day during the prior nine months.
 
The structures cost around 34.5 billion yen (£233m) in public funds and consist of approximately 1,500 tubes filled with brine, cooled to minus 30°C, and buried 30 metres underground.
 
“I believe the ice wall was ‘oversold’ in that it would solve all the release and storage concerns,” said Dale Klein, the former chairman of the US Nuclear Regulatory Commission and the head of an external committee advising Tepco on safety issues.
 
“The hydrology of the Fukushima site is very complicated and thus the exact water flow is hard to predict,” he said, “especially during heavy rains.”
 
Overall, Tepco says a combination of drains, pumps and the ice wall has cut water flows by three-quarters, from 490 tons a day during the December 2015 to February 2016 period to an average of 110 tons a day for December 2017 to February 2018.
 
It is hard to measure exactly how much the ice wall is contributing, Tepco officials say, but based on computer analysis the utility estimates the barrier is reducing water flows by about 95 tonnes a day compared to two years ago, before the barrier was operating.
 
However, it expects to run out of space to store the water by 2021, so the decommissioning process needs to be completed as quickly as possible.
 
In 2016, the estimate for the total cost of the clean-up operation increased to 22.6tr yen (£151bn), more than double the previous estimate.
 
According to a Greenpeace report on Fukushima, published last week, the people, towns and villages in the surrounding area are still being exposed to excessive levels of radiation. A ground-level study conducted by an international research team also found that uranium and other radioactive materials, such as caesium and technetium, were present in tiny particles released from the damaged nuclear reactors.

 

March 14, 2018 Posted by | Fukushima 2018 | , , , | Leave a comment

Experts: Fukushima Must Do More to Reduce Radioactive Water

March 7, 2018
By MARI YAMAGUCHI, Associated Press
A group of experts has concluded that a costly underground ice wall is only partially effective in reducing the ever-growing amount of contaminated water at Japan’s destroyed Fukushima nuclear plant, and that other measures are needed as well.
 
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In this Nov. 12, 2014, file photo, workers wearing protective gears stand outside Fukushima Dai-ichi nuclear power plant’s reactor in Okuma, Fukushima prefecture, northeastern Japan.
A government-commissioned group of experts concluded Wednesday, March 7, 2018 that a costly underground ice wall is only partially effective in reducing the ever-growing amount of contaminated water at Japan’s destroyed Fukushima nuclear plant, and that other measures are needed as well.
 
TOKYO (AP) — A government-commissioned group of experts concluded Wednesday that a costly underground ice wall is only partially effective in reducing the ever-growing amount of contaminated water at Japan’s destroyed Fukushima nuclear plant, and that other measures are needed as well.
The plant’s operator, Tokyo Electric Power Co., says the ice wall has helped reduce the radioactive water by half. The plant also pumps out several times as much groundwater before it reaches the tsunami-damaged reactors via a conventional drainage system using dozens of wells dug around the area.
The groundwater mixes with radioactive water leaking from the damaged reactors.
The panel agreed Wednesday that the ice wall helps, but said it doesn’t completely solve the problem. Panel members suggested that additional measures be taken to minimize the inflow of rainwater and groundwater, such as repairing roofs and other damaged parts of the buildings.
The 1.5-kilometer (1-mile) coolant-filled underground structure was installed around the wrecked reactor buildings to create a frozen soil barrier and keep groundwater from flowing into the heavily radioactive area. The ice wall has been activated in phases since 2016. Frozen barriers around the reactor buildings are now deemed complete.
On Wednesday, TEPCO said the amount of contaminated water that collects inside the reactor buildings was reduced to 95 metric tons per day with the ice wall, compared to nearly 200 tons without one. That is part of the 500 tons of contaminated water created every day at the plant, and the other 300 tons were pumped out via wells, treated and stored in tanks.
In addition to the 35 billion yen ($320 million) construction cost funded by taxpayers’ money, the ice wall needs more than 1 billion yen ($9.5 million) annually in operating and maintenance costs. Critics have been skeptical about the ice wall and suggested that the greater use of wells — a standard groundwater drainage system — would be a cheaper and more proven option.
The plant has been struggling with the ever-growing water — only slightly contaminated after treatment — now totaling 1 million tons and stored in 1,000 tanks, which take up significant space at the complex, where a decades-long decommissioning effort continues. Officials say they aim to further reduce the amount of contaminated water in the reactor buildings before starting to remove melted fuel in 2021.

 

March 7, 2018 Posted by | Fukushima 2018 | , , | Leave a comment

Japan undecided on what to do with 1 million tonnes of radioactive water at Fukushima plant

February 2, 2018
Key points:
The rate of contaminated water reaching the facility has slowed, but is still increasing
There are now more than 1,000 tanks of contaminated water at the site
One controversial option for dealing with the water includes decontaminating it as much as possible and then gradually releasing it into the ocean
 
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Storage tanks for contaminated water at Fukushima nuclear plant
The water is being stored in hundreds of large and densely packed tanks at the plant.
 
Japanese Government officials have not figured out what to do with more than 1 million tonnes of radioactive water sitting at the site of the crippled Fukushima nuclear power plant.
Just days shy of the seventh anniversary of the nuclear disaster, Tokyo Electric Power Company (TEPCO) revealed it successfully slowed the rate of contaminated water reaching the reactor facilities, but the amount was still increasing.
“A few years a go [the radioactive water was increasing by] 400 tonnes per day, but the increase per day has now gone down to around 100 tonnes per day,” said Naohiro Masuda, TEPCO’s chief decommissioning officer.
“A few years ago we had to create one new tank every two or three days but now we need to increase one new tank every seven to 10 days, so in that sense we think it is progress, to a certain degree, in the sense it is a more stabilised situation,” he said.
There are more than 1,000 tanks of contaminated water now at the site — and Government authorities have still not decided what to do with the water.
 
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Aerial view of tanks of contaminated water at the Fukushima nuclear plant
Experts want a gradual release, but if the tanks break the water would slosh out.
 
Ice wall of limited effect
TEPCO revealed earlier this week that its underground frozen soil wall — what was expected to be the main defence against groundwater contamination — had only had a limited effect.
The 1.5-kilometre-long barrier is designed to keep groundwater from flowing into reactor buildings that were damaged by the disaster.
The wall cost more than $US300 million to build and costs $US10 million to operate.
Mr Masuda said it was important to note that the combination of the company’s measures to prevent contamination meant that the situation was less volatile overall.
So while the level of contaminated water is still increasing — albeit at a slower rate — the Japanese Government is yet to agree on what to do with it.
One controversial option includes decontaminating the water as much as possible and then gradually release it into the ocean.
Experts advising the Government have urged a gradual release of the water to the nearby Pacific Ocean.
Treatment can remove all the radioactive elements except tritium, which they say is safe in small amounts.
But local fishermen have balked at the idea, fearing a devastating impact to the reputation of their produce.
Satoru Toyomoto from the Japanese Ministry of Economy, Trade and Industry said a Government sub-committee was still considering its options.
“You may think after as many as seven years [this should be decided], but we have done our utmost and we have done all possible things and we have finally come to a stage where we can consider this,” he said.
“After the accident occurred [in 2011] it was like a field hospital on a battlefield — but finally we have reached a situation where we can calmly think about the long-term future.
“A taskforce two years ago considered various options including geological disposal, vaporisation, burial underground, hydrogen release or release into the sea.
“Of those five options, we are trying to make a comprehensive assessment looking at options, but also reputational measures.”

March 2, 2018 Posted by | Fukushima 2018 | , , | Leave a comment

TEPCO defends Fukushima ‘ice wall,’ but it is still too porous

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Rows of tanks holding contaminated groundwater are seen at the Fukushima No. 1 nuclear power plant in February.
 
The “frozen soil wall” erected around the crippled reactor buildings at the Fukushima No. 1 nuclear power plant at huge taxpayer expense appears limited in keeping groundwater from flowing in.
Tokyo Electric Power Co., which operates the plant, said March 1 that 95 tons of radioactive water has been reduced a day on average between December and early February because of the underground barrier.
“Contaminated groundwater was cut in half due to the wall,” a TEPCO official said.
TEPCO estimated that the volume of polluted groundwater would have amounted to about 189 tons if the ice wall had not been in place during that period.
The utility also said the amount of polluted groundwater was reduced by about 400 tons a day now due to combined measures, such as the wall and wells pumping up water, compared with before such measures were taken.
But Toyoshi Fuketa, chairman of the Nuclear Regulation Authority, has insisted that the wells, not the wall, are the “key” to controlling the groundwater, voicing skepticism about the role of the ice wall.
The utility is proceeding with work to reinforce the wells.
The 34.5 billion yen ($322 million) frozen soil wall project began in 2014 to lay out the 1,500-meter-long underground wall around the No. 1-4 reactor buildings.
A large number of pipes were inserted to a depth of 30 meters to circulate liquid with a temperature of minus 30 degrees through them to freeze the surrounding soil.
It was designed to prevent groundwater from flowing into the plant and mixing with highly radioactive water in the basements of the buildings.
TEPCO’s recent assessment of the effectiveness of the frozen soil wall came after temperatures around the structure dropped to below zero following work that began last August to freeze the remaining final section of the wall.
But experts pointed out that the utility’s assessment is based on figures only when there was little rain.
The water volume rose to 1,000 tons or so a day in late October when two typhoons struck the area.
TEPCO believes that the surge at that time is largely attributable to the downpours from the typhoons.
Heavy rain accumulated in the basement after flowing down holes in the ceilings caused by hydrogen explosions during the 2011 triple meltdown.
It costs more than 1 billion yen a year in electricity fees to keep the wall frozen.
The company plans to remove all the groundwater from the buildings by 2020 so that it can begin work to decontaminate the facilities later.

March 2, 2018 Posted by | Fukushima 2018 | , | Leave a comment

TEPCO: Frozen soil wall effect limited

 

2018/03/01
Tokyo Electric Power Company, or TEPCO, says an underground frozen soil wall around its Fukushima Daiichi nuclear plant has had a limited effect in reducing groundwater contamination.
 
The 1.5-kilometer-long barrier is designed to keep groundwater from flowing into reactor buildings that were damaged by the March 2011 earthquake, tsunami and nuclear meltdowns.
 
The wall was expected to be the main defense against groundwater contamination, as about 500 tons of water was being tainted daily by radioactive substances.
 
TEPCO officials on Thursday estimated the amount of new contaminated water to have decreased by about 95 tons a day from before the wall was built.
They said the estimate is based on 3 months of data including that from before and after the wall was almost completed last November.
 
TEPCO had introduced a so-called sub-drain system for pumping up water from wells dug around the buildings.
 
The officials estimated that the 2 measures resulted in a decrease of 380 tons of tainted groundwater a day, suggesting the wall’s effectiveness is limited and lower than that of the drain method.
 
The government plans to ask experts to look into whether the utility’s estimate is accurate.
 
Public funds worth over 300 million dollars have been used to build the wall. Its annual operating cost exceeds ten million dollars.
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March 1, 2018 Posted by | Fukushima 2018 | , , , | Leave a comment

Fukushima ‘ice wall’ linchpin not living up to high hopes

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Although 34.5 billion yen ($309 million) in taxpayer money has funded an “ice wall” to keep out groundwater from the Fukushima No. 1 nuclear power plant site, the frozen barrier may not be meeting hopes and expectations.
In particular, the wall has been vulnerable to heavy rain brought by typhoons.
Reducing the volume of radiation-contaminated water is vital to proceeding with the removal of melted fuel from the reactors at the Fukushima No. 1 plant so it can be decommissioned.
But officials of Tokyo Electric Power Co., the operator of the plant, are still not completely sure if the ice wall is performing as designed.
Heavy rain appears to pose a major problem because the ice wall has so far proved incapable of stopping groundwater when typhoons have passed near the plant.
In theory, the ice wall should serve as a dam to prevent groundwater from the mountainside of the plant from flowing into the reactor buildings.
The total length of the wall is about 1,500 meters, and the wall surrounds the reactor and turbine buildings of four reactors at the No. 1 plant. Pipes have been buried about 30 meters deep at one-meter intervals.
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Liquid at temperatures of minus 30 degrees have been poured into the pipes to freeze the surrounding ground. Freezing of the final section of the wall began on Aug. 22, but TEPCO officials on Nov. 22 still stopped short of offering an assessment of whether the ice wall was actually working as planned.
Utility officials have said that after about two months, ground temperatures where the freezing had begun have fallen below 0 degrees.
The estimated volume of groundwater that has leaked into the reactor and other buildings was 190 tons a day at the start of 2016, but it had decreased to 110 tons a day by early October.
However, the situation changed dramatically when two typhoons passed by in late October.
The groundwater level rose rapidly and the average daily flow of groundwater into the building basements for October was estimated to be 310 tons. That was close to the 400 tons that was flowing into the building basements before any measures were implemented to deal with the contaminated water.
There was no realistic expectation of building a ice wall that would keep out all groundwater because the pipes had to be buried in a way that would avoid underground piping from the reactors that were already in place. That meant there were underground portions that could not be frozen.
Masashi Kamon, a professor emeritus at Kyoto University who specializes in environmental geotechnics, said TEPCO should have considered a number of measures to stem the flow of groundwater from the long-term perspective of eventually removing the melted fuel from the reactors.
Another measure that is receiving more attention of late is pumping up groundwater from the 42 wells located around the reactor buildings and releasing it into the ocean. TEPCO plans to double the number of pumps and processing capacity of decontamination facilities by early 2018.
But other measures will likely have to be considered before work can begin to remove melted fuel from the reactor cores. The first step would be to remove as much as possible the highly radioactive water that remains in the reactor building basements. Such water poses a huge risk to the workers who will have to enter the buildings to remove the fuel.
Toyoshi Fuketa, chairman of the Nuclear Regulation Authority, said the ice wall was a measure implemented when the situation was much more serious, but that now is the time for calmer consideration about whether that investment of time and money was the proper one.

November 28, 2017 Posted by | Fukushima 2017 | , | Leave a comment

Frozen soil wall nearly complete; NRA still doubts effect

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A construction project to create frozen soil walls that encircle the ground beneath Tokyo Electric Power Company Holdings Inc.’s disaster-hit Fukushima No. 1 nuclear power plant is nearly finished.
Although TEPCO insists that the inflow of groundwater beneath the reactor buildings has been reduced, some members of the Nuclear Regulation Authority are skeptical about the project’s effectiveness. With ¥34.5 billion of public funds being spent on this project, the centerpeice of countermeasures for contaminated water, its cost-effectiveness is being carefully watched.
The project entails building a 1.5-kilometer-long frozen soil wall encircling the Nos. 1 to 4 reactors, with 1,568 pipes buried to a depth of about 30 meters below ground and coolant running through the pipes at minus 30 C to chill the soil.
The process is expected to prevent groundwater from flowing into the contaminated, highly radioactive underground water at such sites as the reactor buildings, and to avoid an increase of contaminated water.
The project began in March last year, and operations to freeze the final section, about seven meters wide, on the mountain side began in August this year.
The temperature of the underground soil has remained below zero, except for a part close the surface that is affected by outdoor air, meaning the project to create the 30-meter-deep walls is almost complete.
According to TEPCO’s assessment, before the project started, about 400 tons of groundwater was flowing into the ground underneath the reactor buildings and other sites daily.
TEPCO had initially calculated that the daily inflow of groundwater could decrease to dozens of tons once the walls were installed. However, between April and September the inflow per day was between 120 tons and 140 tons, and in October it was around 100 tons. That the amount of inflow has decreased in stages as the soil freezing progressed seems to prove that the project has been effective to a certain extent. However, it is unclear if the inflow will decrease further in the future.
In parallel with the frozen soil wall project, TEPCO dug about 40 subdrain wells to pump up groundwater before it flows into the reactor buildings. It also reinforced measures to prevent rainwater from soaking into the ground by paving 1.33 million square meters of surface.
In the NRA view, those measures must also contribute greatly to reducing the inflow, casting doubt on the frozen soil walls project by saying the effect of them alone may be limited. The agency has become distrustful of TEPCO and urged the company to verify the effects.
Hiroshi Miyano, visiting professor at Hosei University specializing in system safety, said: “There is sure to be a part that doesn’t freeze completely, and it’s impossible to reduce the inflow to zero. TEPCO must continue applying this measure in tandem with draining the nearby wells for a while.”

November 9, 2017 Posted by | Fukushima 2017 | , | Leave a comment

Fukushima ice wall facing doubts as project nears completion

Barrier will block only a fraction of groundwater contamination

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Work has begun on the final 7 meters of an “ice wall” at the Fukushima Dai-ichi nuclear power plant.

 

TOKYO — Tokyo Electric Power Co. Holdings began Tuesday the final phase of an underground “ice wall” around the crippled Fukushima Daiichi nuclear power plant intended to reduce groundwater contamination, though experts warn the bold project could be much less effective than once hoped.

At 9 a.m., workers began activating a refrigeration system that will create the last 7 meters of a roughly 1.5km barrier of frozen earth around the plant’s reactor buildings, which were devastated by the earthquake, tsunami and nuclear meltdowns of March 2011. Masato Kino, an official from the Ministry of Economy, Trade and Industry supervising the cleanup, spoke cautiously at the occasion, noting that “producing results is more important than the simple act of freezing” that particular segment of soil.

Tepco estimates that roughly 580 tons of water now pass through the ice wall on the reactor buildings’ landward side each day, down from some 760 tons before freezing of soil commenced in March 2016. About 130 tons daily enter the reactor buildings themselves, and Tepco hopes completing the wall will bring that figure below 100 tons.

By this math, the near-complete wall blocks only a little over 20% of groundwater coming toward it. But, as Japan’s Nuclear Regulation Authority said Aug. 15 when approving the wall’s final stage, the barrier is “ultimately only a supporting measure” to other systems preventing contamination. The main line of defense is a so-called subdrain system of 41 wells around the reactor buildings that pump up 400 to 500 tons of water daily, preventing clean water from entering the site and contaminated water from leaving it.

Slow going

Freezing of earth around the facility has been conducted gradually, amid concerns that highly contaminated water inside could rush out should the water level inside the reactor buildings drop. “Working carefully while keeping control of the water level is a must,” said Yuzuru Ito, a professor of civil and environmental engineering at Setsunan University.

It is unclear precisely when the wall will be complete. The plan is to freeze soil 30 meters deep over the course of two or three months, completing the barrier as soon as this fall. But as the gap in the wall narrows, water flows through it more quickly, making soil there more difficult to freeze. “Water is flowing quickly now, and so it is difficult to proceed as we have so far,” a Tepco representative said.

Japan has spent some 34.5 billion yen ($315 million) in taxpayer funds on the wall, expecting the icy barrier to put a decisive end to groundwater contamination at the Fukushima plant. It now appears that a dramatic improvement is not likely, though the wall will still require more than 1 billion yen per year in upkeep. “The frozen-earth barrier is a temporary measure,” said Kunio Watanabe, a professor of resource science at Mie University. “Some other type of wall should be considered as well.”

https://asia.nikkei.com/Tech-Science/Tech/Fukushima-ice-wall-facing-doubts-as-project-nears-completion

 

August 23, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

High-priced Fukushima ice wall nears completion, but effectiveness doubtful

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A subterranean ice wall surrounding the nuclear reactors at the stricken Fukushima No. 1 Nuclear Power Plant to block groundwater from flowing in and out of the plant buildings has approached completion.

Initially, the ice wall was lauded as a trump card in controlling radioactively contaminated water at the plant in Fukushima Prefecture, which was crippled by meltdowns in the wake of the March 2011 Great East Japan Earthquake and tsunami. But while 34.5 billion yen from government coffers has already been invested in the wall, doubts remain about its effectiveness. Meanwhile, the issue of water contamination looms over decommissioning work.

In a news conference at the end of July, Naohiro Masuda, president and chief decommissioning officer of Fukushima Daiichi Decontamination & Decommissioning Engineering Co., stated, “We feel that the ice wall is becoming quite effective.” However, he had no articulate answer when pressed for concrete details, stating, “I can’t say how effective.”

The ice wall is created by circulating a coolant with a temperature of minus 30 degrees Celsius through 1,568 pipes that extend to a depth of 30 meters below the surface around the plant’s reactors. The soil around the pipes freezes to form a wall, which is supposed to stop groundwater from flowing into the reactor buildings where it becomes contaminated. A total of 260,000 people have worked on creating the wall.

ice wall 16 august 2017 2.jpgThis photo shows pipes to freeze soil for the ice wall next to the No. 4 reactor at TEPCO’s Fukushima No. 1 Nuclear Power Plant, in Okuma, Fukushima Prefecture, on June 1, 2016. (Mainichi)

 

The plant’s operator, Tokyo Electric Power Co. (TEPCO) began freezing soil in March last year, and as of Aug. 15, at least 99 percent of the wall had been completed, leaving just a 7-meter section to be frozen.

Soon after the outbreak of the nuclear disaster, about 400 tons of contaminated water was being produced each day. That figure has now dropped to roughly 130 tons. This is largely due to the introduction of a subdrain system in which water is drawn from about 40 wells around the reactor buildings. As for the ice wall, TEPCO has not provided any concrete information on its effectiveness. An official of the Secretariat of the Nuclear Regulation Authority (NRA) commented, “The subdrain performs the primary role, and the ice wall will probably be effective enough to supplement that.” This indicates that officials have largely backtracked from their designation of the ice wall as an effective means of battling contaminated water, and suggests there is unlikely to be a dramatic decrease in the amount of decontaminated groundwater once the ice wall is fully operational.

TEPCO ordered construction of the ice wall in May 2013 as one of several plans proposed by major construction firms that was selected by the government’s Committee on Countermeasures for Contaminated Water Treatment. In autumn of that year Tokyo was bidding to host the 2020 Olympic and Paralympic Games, and the government sought to come to the fore and underscore its measures to deal with contaminated water on the global stage.

Using taxpayers’ money to cover an incident at a private company raised the possibility of a public backlash. But one official connected with the Committee on Countermeasures for Contaminated Water Treatment commented, “It was accepted that public funds could be spent if those funds were for the ice wall, which was a challenging project that had not been undertaken before.” Small-scale ice walls had been created in the past, but the scale of this one — extending 1.5 kilometers and taking years to complete — was unprecedented.

At first, the government and TEPCO explained that an ice wall could be created more quickly than a wall of clay and other barriers, and that if anything went wrong, the wall could be melted, returning the soil to its original state. However, fears emerged that if the level of groundwater around the reactor buildings drops as a result of the ice wall blocking the groundwater, then tainted water inside the reactor buildings could end up at a higher level, causing it to leak outside the building. Officials decided to freeze the soil in stages to measure the effects and effectiveness of the ice wall. As a result, full-scale operation of the wall — originally slated for fiscal 2015 — has been significantly delayed.

ice wall 16 august 2017.jpgA worker makes checks with a hammer on an impermeable wall near TEPCO’s No. 4 reactor in the town of Okuma in Fukushima Prefecture on Feb. 24, 2017. (Mainichi)

 

Furthermore, during screening by the NRA, which had approved the project, experts raised doubts about how effective the ice wall would be in blocking groundwater. The ironic reason for approving its full-scale operation, in the words of NRA acting head Toyoshi Fuketa, was that, “It has not been effective in blocking water, so we can go ahead with freezing with peace of mind” — without worrying that the level of groundwater surrounding the reactor buildings will increase, causing the contaminated water inside to flow out.

Maintaining the ice wall will cost over a billion yen a year, and the radiation exposure of workers involved in its maintenance is high. Meanwhile, there are no immediate prospects of being able to repair the basement damage in the reactor buildings at the crippled nuclear plant.

Nagoya University professor emeritus Akira Asaoka commented, “The way things stand, we’ll have to keep maintaining an ice wall that isn’t very effective. We should consider a different type of wall.”

In the meantime, TEPCO continues to be plagued over what to do with treated water at the plant. Tainted water is treated using TEPCO’s multi-nuclide removal equipment to remove 62 types of radioactive substances, but in principle, tritium cannot be removed during this process. Tritium is produced in nature through cosmic rays, and nuclear facilities around the world release it into the sea. The NRA takes the view that there is no problem with releasing treated water into the sea, but there is strong resistance to such a move, mainly from local fishing workers who are concerned about consumer fears that could damage their businesses. TEPCO has built tanks on the grounds of the Fukushima No. 1 plant to hold treated water, and the amount they hold is approaching 800,000 metric tons.

In mid-July, TEPCO Chairman Takashi Kawamura said in an interview with several news organizations that a decision to release the treated water into the sea had “already been made.” A Kyodo News report on his comment stirred a backlash from members of the fishing industry. TEPCO responded with an explanation that the chairman was not stating a course of action, but was merely agreeing with the view of the NRA that there were no problems scientifically with releasing the treated water. However, the anger from his comment has not subsided.

Critical opinions emerged in a subsequent meeting that the Ministry of Economy, Trade and Industry held in the Fukushima Prefecture city of Iwaki at the end of July regarding the decontamination of reactors and the handling of contaminated water. It was pointed out that prefectural residents had united to combat consumer fears and that they wanted officials to act with care. One participant asked whether the TEPCO chairman really knew about Fukushima.

The ministry has been considering ways to handle the treated water, setting up a committee in November last year that includes experts on risk evaluation and sociology. As of Aug. 15, five meetings had been held, but officials have yet to converge on a single opinion. “It’s not that easy for us to say, ‘Please let us release it.’ It will probably take some time to reach a conclusion,” a government official commented.

https://mainichi.jp/english/articles/20170816/p2a/00m/0na/016000c

 

August 17, 2017 Posted by | Fukushima 2017 | , | Leave a comment

Japanese Nuclear Regulator Permits Completion of ‘Ice Wall’ Beneath Fukushima

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Japan’s Nuclear Regulation Authority has approved the completion of the remaining parts of the Fukushima nuclear power plant’s “ice wall” ground freeze beneath the station in order to prevent groundwater from entering the damaged reactor’s facilities, local media reported Tuesday.

MOSCOW (Sputnik) – The plan stipulates creating a 0.9 mile long barrier by circulating coolant of 30 degrees below zero in pipes buried around the building. The “ice wall” is expected to keep groundwater from entering the station and therefore prevent an increase in amounts of water contaminated by radioactive substances. Initially, the Nuclear Regulation Authority was concerned with the fact that if the whole wall was created, it would probably lead to a drastic decrease in water in the area around the station and cause leakages of contaminated water outside the damaged reactor’s building. Experts thus previously ruled to leave a 23-foot section of the wall unfrozen.

According to the NHK broadcaster, the Tokyo Electric Power Company (TEPCO), responsible for the project, claimed that the completion of the wall would not result in a sudden decrease of water levels, and even if it would, the company promised to take immediate measures. After considering the company’s position, experts allowed to complete the “ice wall.”

The broadcaster said that TEPCO will begin the remaining work on August 22, completing the soil freeze that first began in March 2016. It was also reported that after the works are completed, the Nuclear Regulation Authority would carefully assess the results and examine whether there have been any positive improvements in water contamination.

In 2011, a major earthquake triggered a tsunami that hit Japan’s Fukushima NPP and led to the leakage of radioactive materials and the shutdown of the plant. Following the incident, Tokyo shut down all the NPPs in Japan and began to restart them after introducing new security standards.

https://sputniknews.com/asia/201708151056482387-japan-fukushima-ice-wall/

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August 17, 2017 Posted by | Fukushima 2017 | , | Leave a comment

Fukushima ice wall nears completion

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An underground ice wall being built to keep groundwater from entering the crippled nuclear reactor buildings in Fukushima is expected to be completed soon.

Workers at the Fukushima Daiichi nuclear power plant are circulating coolant in pipes buried around the buildings to make the 1.5 kilometer-long barrier.

The operator, Tokyo Electric Power Company, hopes to keep groundwater from being contaminated with radioactive substances.

The utility has so far left part of the wall unfrozen, due to fears that freezing the entire area could lead to a sharp drop in groundwater levels outside the reactor buildings, which could cause the tainted water to leak out.

On Wednesday, the Nuclear Regulation Authority gave basic approval for the utility’s plan to freeze a 7 meter-wide section that remains on the mountain side.

Utility officials have explained to authority members that the groundwater level won’t plunge and that they are prepared for such an emergency.

TEPCO says that as soon as it gets official approval it will start freezing the remaining section of the wall. It has been functioning for about 15 months.

The daily amount of groundwater flowing into the buildings is now about 100 tons, compared with some 400 tons per day at the start of the operation.

The utility says the completion of the ice wall will further reduce the amount. The regulators plan to monitor the effects of the barrier after it is completed.

https://www3.nhk.or.jp/nhkworld/en/news/20170628_30/

June 30, 2017 Posted by | Fukushima 2017 | , | Leave a comment

Fukushima’s Ice-wall Blossoming or Not?

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Following the Fukushima nuclear disaster of 2011, it was rapidly discovered that owing to the unfortunate location of the plant and its construction, its buildings’ basements had become flooded by groundwater ingress, which subsequently became highly contaminated. In order to avoid reverse diffusion of the contaminated water into the environment, those managing the site were compelled to continually pump out and treat the contaminated water, at a rate commensurate with its inflow. It was anticipated or perhaps it would be better stated as ‘earnestly hoped’, that by keeping the water level in the flooded building basement below ground water levels that contamination would not defuse out of the flooded basement. Naturally as a consequence TEPCO are accumulating and endeavouring to store and decontaminate the net amount of water ingress each day.

To facilitate containment necessary for the safe decommissioning of the immediately contaminated reactor buildings in September 2013 TEPCO commissioned the construction of their controversial ‘ice-wall’.[1] Installation of the facilities to create the ice-wall commenced in June 2014 and was completed on February 9, 2016 at an estimated to cost some ¥34.5 billion (circa $339 million). Activation was on March 31, 2016, with commencement of the freezing of the seaward side wall. Freezing of the land-side wall commenced on June 6, 2016, with the secondary phase of sealing the last openings in the land side wall commencing on December 2, 2016. At this point we should note that the ice-wall in not penetrating to the depth of the aquifer, has no base to its containment, thus the wall is little more than a skirt, with water free to percolate in and out from below the contaminated site.

We now find ourselves in the spring of 2017, with the ice-wall’s chillier plant having run flat out for a year with seemingly little net impact on water ingress. Frustrated by this apparent lack of progress, on December 26, 2016 the Japanese Nuclear Regulatory Authority (NRA) citing “limited, if any effects,” advised TEPCO that the “frozen soil wall” should be relegated to a secondary role in reducing contaminated groundwater at the Fukushima No. 1 nuclear plant.[2] Yet TEPCO still persisted in asserting that the ice-wall was effective stating “We are seeing certain results.” Which begs the questions: What results were they seeing and as TEPCO’s response would suggest, have the NRA been too presumptive in dismissing the ice-wall’s impact and groundwater ingress? Or perhaps TEPCO’s engineers, being so bought into their radical ice-wall concept they don’t want to ‘lose face’ or perhaps they have simply lost the plot?

In a bid to head of criticising of their activities for being less than transparent and tardy in properly advising the public, TEPCO have conveniently put certain of their findings into the public domain, in the form of press releases.[3] From this data, it’s possible to get a rudimentary grasp of what’s going on beneath TEPCO’s ice-wall. Regular updates on volumes of contaminated waters pumped from drainage wells and the reactor buildings’ basement, along with local rainfall have been regularly published. These indicated the seasonal cycle of rainfall in the Fukushima area and further show a relationship between local rainfall and the volumes of water, (Figure 1).

Figure 1

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Working on the basis of the limited available data and an anticipated lag between rain falling and its impact on groundwater, and assuming a direct relationship between water ingress and the total amount of water transferred or pumped out of the system, we can drive a relationship between the averaged daily water transfer (a measure of approximate water ingress) and the rainfall total for the prior month, (Figure 2). These criteria show very plausible cause effect linear correlation (i.e. of the type, y = mx + c), (Figure 3). Thus, we can envisage the contributions to groundwater flow within the aquifer beneath Fukushima being comprised of two portions (a) a large steady flow arising from rainfall which may have fallen years to decades ago on the mountains to the west of the site and equating to the linear equation’s constant and (b) a highly variable amount of flow arising from recent rainfall, predominantly within the last month.

Figure 2

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Figure 3

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Whilst the linear relationship between the phenomena is simplistic, on the available data application of 2nd or 3rd order polynomial curve fitting does not give any significant improved correlation coefficient (R). Given we have identified the correlation and observe seasonality, we can factor out the seasonality and project rolling annualised rainfall and water transfer (Figure 4).

Figure 4
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Within the scope of natural variance, the annualised rainfall at Fukushima shows no significant long term trend, being flat and circa 1.5 metres per year. The water transfer level does show some improvement and notwithstanding the slightly higher than average autumnal rains in 2016, water transfer levels are on the decline. Alas given the magnitude of that decline in relation to that hoped for by the ice-wall’s advocates to 50 tonnes per day, it was understandable that the NRA were rather less than impressed.

We also have to consider that our original correlation between rainfall and implied water ingress was conducted on all available data. The reality is several operational events were being executed over the period, such as the commencement of 24 hour pumping from inland relief wells with the aim of reducing groundwater around the stricken buildings, as well as the phased installation of the ice-wall itself. Thus our initial correlation is a composite of parallel events. If we reapply our linear relationship model on a rolling 12 monthly period, to exclude any rainfall seasonality, we see some interesting features, (Figure 5). 

Figure 5
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Had the ice-wall achieve a positive effect we should observed both a reduction in total amount of water transferred (y) being made up by a reduction in the overall basal flow (c) and of course a reduction in the recent rainfall component as reflected in a reduction of its independent variable (m). We see a reduction in apparent basal flow. As this reduction has occurred in isolation with the independent variable increasing over time, we can attribute reduction in ‘c’ in good measure to the impact relief wells. However, the overall amount of water being pumped out of the stricken buildings has remained high and it has done so because the aquifer has become more susceptible to the impact of recent rainfall. This suggests that the aquifer adjacent the site has become more porous and not less porous over the last few years. Had the ice-wall had a positive effect, a decline in the independent variable ‘m’ over time should be observed.

I would conjecture that if such is the case what could have caused this effect. It is possible that the installation of the coolant pipe-work has caused significant sub-soil disturbance, coupled with the degradation of the substrate rock texture by ground heave. The above should effectively have been self repaired when the ice-barrier froze. However, in this circumstance, owing to the size of the ice-wall and it lack of capacity to freeze the entire depth of the aquifer, it is likely that the aquifer disruption at its margins has resulted in increased porosity in the aquifer directly beneath the wall. Furthermore, given that the wall is incomplete and operating at the extent of its capacity, and that the site is subject to seasonal warming, and has had operational outages it is highly likely that the freeze thaw cycling peripheral to the ice-wall has cause deterioration to the aquifers subsoil texture and cohesion, thereby giving rise to localised increase porosity of the aquifer. As such I am not of the opinion that the installation of the ice-wall has had a ‘limited impact’. I believe it has had a ‘significant and negative impact’ on the porosity of the aquifer local to the site of contamination, and I believe it has added circa 20% to the volume of contaminated water generated since its installation.

But there again, that’s just one persons musings and opinion, and I dare say other will disagree and think I’m writing bollocks. Either way, I would be fascinated to see what “certain results” the TEPCO engineers saw. And if what they saw was good, I’d like a double of whatever they’d been drinking…

Kanpai
[1] 11 July 2016, ‘Fukushima’s Ice-Wall a Fridge Too Far’ Peter J. Hurley, Linkedin.com https://www.linkedin.com/pulse/fukushimas-ice-wall-fridge-too-far-peter-j-hurley

[2] December 27, 2016 Kohei T., The Asahi Shimbun ‘NRA: Ice wall effects ‘limited’ at Fukushima nuclear plant’: http://www.asahi.com/ajw/articles/AJ201612270056.html

[3] http://www.tepco.co.jp/en/nu/fukushima-np/handouts/index-e.html


https://www.linkedin.com/pulse/fukushimas-ice-wall-blossoming-peter-j-hurley?trk=v-feed&lipi=urn%3Ali%3Apage%3Ad_flagship3_feed%3B%2BRPMF%2BmRHiG1ZXRh%2ByoBrw%3D%3D

April 13, 2017 Posted by | Fukushima 2017 | , , , | Leave a comment