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Efficacy unclear of problem-hit ice-soil wall at Fukushima plant

Pipes are set up around reactor buildings to form an ice wall in October 2016 at Tokyo Electric Power Co.’s Fukushima No. 1 nuclear power plant.

May 12, 2022

Technical flaws, ballooning costs and unconfirmed effectiveness have plagued the “ace card” in preventing groundwater from accumulating within the crippled Fukushima No. 1 nuclear power plant.

Plant operator Tokyo Electric Power Co. froze the soil to create an underground ice wall to divert the groundwater toward the ocean and away from the damaged reactor buildings where the liquid can become heavily contaminated with radioactive substances.

The 1.5-kilometer ice wall was completed in 2016 around the No. 1 to No. 4 reactor buildings of the nuclear plant. The ice barrier was initially expected to end its role in 2021, after steps were taken to prevent water leaks and plug holes at the reactor buildings.

Not only has the ice wall failed to work sufficiently, but huge amounts of public funds also continue to pour in annually for its maintenance.

“A frozen ground wall has advantages, such as a high ability to block water, but its maintenance requires huge sums,” said Kunio Watanabe, a professor of frozen soil studies at Mie University. “An easy-to-build underground ice wall was the only possible option in the early stages because of extremely high radiation readings around the reactor buildings.

“Now that it has been used for so many years, other approaches should also be weighed.”

TECHNICAL PROBLEMS, RISING SPENDING

TEPCO has used tanks to store contaminated water used to cool the melted nuclear fuel since the Great East Japan Earthquake and tsunami caused the triple meltdown at the plant.

But it is also storing the groundwater that keeps flowing in. Space for the water storage tanks at the nuclear plant is running out.

The ice wall was supposed to reduce the volume of contaminated water.

In October last year, TEPCO said the soil temperature was higher than 0 degrees in an area that should have been frozen. The temperature reportedly topped 0 in mid-September and increased to 13 degrees in November.

TEPCO said equipment to discharge rainwater accumulating in a different reactor building broke down. The rainwater there likely seeped into the ground and reached the spot with the temperature increase.

Steel sheets were inserted into the soil to stanch the groundwater flow.

A total of 1,568 cooling pipes extending 30 meters below the surface circulate a refrigerant of minus 30 degrees to freeze the soil.

However, 14 tons of the coolant leaked between January and February this year because of damaged pipes and slippage of rubber parts at their joints.

TEPCO located the leaks and replaced the pipes, but the coolant’s circulation was suspended during the procedure.

The barrier system was brought into operation using 34.5 billion yen ($268 million) in taxpayers’ money.

Since the soil must be kept frozen throughout the year, electricity charges and other expenses for cooling and circulating the refrigerant continue to grow.

Annual maintenance costs topped 1 billion yen immediately following the wall’s introduction, and hundreds of millions of yen are currently injected in the system each year.

UNCERTAIN VALIDITY

Despite all the fixes and expenses, the strategy’s effectiveness has yet to be verified.

TEPCO in March 2018 released an estimate arguing the frozen wall would prevent 95 tons of groundwater from entering the plant daily. That level would be half of the inflow with no underground barriers.

The prediction, however, was exclusively for winter months with less rainfall. It did not include torrential rain from typhoons that increase the amount of groundwater flowing into the reactor buildings.

TEPCO recently declined to comment on the ice wall’s effectiveness, saying it is “difficult to assess individual countermeasures because many steps are being implemented simultaneously.”

Frozen soil barriers are normally used for only several months in tunnel digging and other construction projects. There have been few large ice walls that have been operated for years.

The government and TEPCO originally planned to rely on the method “until March 2021, when countermeasures against water leaks at reactor buildings are finished.”

But they have not started on the anti-leakage process for the structures.

They do, however, plan to release treated water stored at the plant into the sea, a proposal that has been criticized by residents and the fishing industry.

Radioactive water increases by 150 tons a day at the Fukushima plant.

TEPCO set a goal of lowering the daily contaminated water rise to 100 tons or less by 2025. It described the “frozen soil wall as equipment essential for accomplishing the objective.”

TEPCO in December last year told the Nuclear Regulation Authority that it will continue to use the frozen wall system.

“We will consider the next step,” a TEPCO official said. “We are sorting out alternatives so a new approach will be realized in 2024 or 2025.”

https://www.asahi.com/ajw/articles/14605126?fbclid=IwAR3CJaz-u8n23Hpz0m8to-VNTB3xBUZKj9MuqB6M9-QKsXXSV1oo4LenWL8

May 15, 2022 Posted by | Fuk 2022 | , | Leave a comment

Leakage of liquid from frozen soil wall caused by misalignment of pipe joints TEPCO

January 25, 2022

Leakage of liquid from frozen soil wall caused by misalignment of pipe joints TEPCO

As part of the measures to deal with contaminated water at the Fukushima Daiichi Nuclear Power Plant, liquid used to freeze the ground leaked from the “frozen earth wall” that was installed to prevent underground water from flowing into the buildings. The Tokyo Electric Power Company (TEPCO) is investigating the cause of the damage and replacing the pipes.

On the 16th of this month at the Fukushima Daiichi Nuclear Power Plant, an estimated 4 tons of liquid at minus 30 degrees Celsius, which is used as a “refrigerant” to build a “frozen earth wall” to freeze the ground around the buildings, leaked. The leakage was estimated to be about 4 tons.

Tokyo Electric Power Company (TEPCO) investigated the leak and found that the joints between the pipes that feed the refrigerant and the underground pipes used to freeze the ground had shifted.

The parts of the joint were replaced by the 22nd of this month. The parts of other pipes will be replaced in the future and the cause of the shift of the joint is still being investigated.
https://www3.nhk.or.jp/lnews/fukushima/20220125/6050017050.html?fbclid=IwAR2oxPXF79fFf2r3EpIMvW7CLRrpys6OdsKPbPJuOeGf0_344tVeP6VBaxo

January 26, 2022 Posted by | Fuk 2022 | , , | Leave a comment

TEPCO reports coolant solution leakage at Fukushima nuclear plant

University students rally in front of the Japanese Embassy in South Korea to protest the Japanese government’s decision to dump nuclear wastewater into the sea, in Seoul, April 14, 2021. /CFP

23-Jan-2022

Tokyo Electric Power Company (TEPCO), the operator of Japan’s crippled Fukushima nuclear power plant, has discovered that a coolant solution used to create an ice wall halting groundwater seepage into the reactor buildings has leaked from two storage tanks, Reuters reported on Sunday.

The company claims that there has been no impact on the wall or the environment, according to the report.

Still, it underscores the unpredictable challenges in the clean-up of the site, nearly 11 years after an earthquake and tsunami ravaged Japan’s northeastern coast, causing the world’s worst nuclear disaster since the Chernobyl accident in 1986.

On Sunday, TEPCO spokesperson Tsuyoshi Shiraishi said about four tonnes of a calcium chloride solution used to maintain the ice wall had leaked for the eighth time.

In the last such accident in December 2019, 16 tonnes spilled, likely due to metal fatigue resulting from vibrations caused by construction vehicles, Shiraishi said, adding that TEPCO is “now confirming the reason.”

There was no immediate impact on the wall’s function as it takes several months for the wall to thaw in the absence of coolant, he said.

Work on the underground frozen wall around unit 1-4began in June 2014 to block the flow of groundwater into the plant’s basements, according to China Media Group.

The 1.5-kilometer wall, which became operational in 2017, is made up of 1,568 pipes filled with a refrigerant and inserted 30 meters underground, turning the soil into a solid mass.

Only last year, Japan’s government approved the release of over 1 million tonnes of irradiated water from the site after treatment, starting around spring 2023. TEPCO last month said it would build a tunnel reaching into the sea for the operation.

Separately, a group of six men and women is set to file on January 27 a lawsuit against TEPCO claiming they developed thyroid cancer due to exposure to radiation from the Fukushima disaster, the Mainichi newspaper reported.

https://news.cgtn.com/news/2022-01-23/TEPCO-admits-coolant-solution-leaked-at-Fukushima-nuclear-plant-173qEVNvCPm/index.html

January 24, 2022 Posted by | Fuk 2022 | , , | Leave a comment

Coolant solution leaks at Fukushima Daiichi plant

The frozen wall was a temporary solution for maximum 7 years and the time has run out anyway.

Jan. 22, 2022

The operator of the crippled Fukushima Daiichi nuclear power plant says coolant solution used to create a frozen soil wall around reactor buildings has leaked.

The underground barrier is meant to block groundwater from flowing into the reactor buildings that were damaged as a result of the 2011 earthquake and tsunami.

Tokyo Electric Power Company has been using a calcium chloride solution to maintain the barrier. The firm has been storing the liquid at minus 30 degrees Celsius in four tanks.

TEPCO says liquid levels in two of the tanks dropped on January 16. It says its workers found a pool of the solution near the wall and estimated roughly 4 tons of it had leaked.

The utility says the wall remains capable of keeping groundwater out as it takes several months before the barrier begins to thaw. It adds that the solution does not harm the environment.

TEPCO says the pipe circulating the solution may have been partially damaged. It says it will pinpoint the damaged section and fix it as soon as possible.

January 24, 2022 Posted by | Fuk 2022 | , , | Leave a comment

Japan’s Tepco hit by setback in clean-up of crippled Fukushima nuclear plant

Good faith does not exist in Tepco’s dictionary!

TOKYO, Jan 23 (Reuters) – The operator of Japan’s crippled Fukushima nuclear power plant has found that a coolant solution, used to create an ice wall halting the seepage of groundwater into reactor buildings, has leaked from two storage tanks.

The leakage has had no impact on the wall or environment, said Tokyo Electric Power Co Holdings Inc (Tepco) (9501.T).

Still, it underscores the unpredictable challenges in the clean-up of the site, nearly 11 year after an earthquake and tsunami ravaged Japan’s northeastern coast, causing the world’s worst nuclear disaster since Chernobyl, Ukraine, in 1986.

Only last year, Japan’s government approved the release of over 1 million tonnes of irradiated water from the site after treatment, starting around spring 2023. Tepco last month said it would build a tunnel reaching into the sea for the operation. read more

On Sunday, Tepco spokesperson Tsuyoshi Shiraishi said about four tonnes of a calcium chloride solution used to maintain the ice wall had leaked in what was the eighth such leakage.

“We’re now confirming the reason,” he said.

The last leak in December 2019 saw 16 tonnes spilled, likely due to metal fatigue resulting from vibrations caused by construction vehicles, Shiraishi said.

There was no immediate impact on the wall’s function as it takes several months for the wall to thaw in the absence of coolant, he said.

Separately, a group of six men and women is set to file on Jan. 27 a lawsuit against Tepco claiming they developed thyroid cancer due to exposure to radiation from the Fukushima disaster, the Mainichi newspaper reported.

The plaintiffs, who were minors living in Fukushima prefecture at the time of the 2011 disaster, are seeking 616 million yen ($5.42 million) in compensation from the electricity provider, the Mainichi said.

If the complaint was served, Tepco would respond in good faith after hearing the contents of the claims and arguments in detail, the firm said in a statement.

https://www.reuters.com/world/asia-pacific/japans-tepco-hit-by-setback-clean-up-crippled-fukushima-nuclear-plant-2022-01-23/

January 24, 2022 Posted by | Fuk 2022 | , , | Leave a comment

Leakage of 4 tons of liquid at minus 30 degrees Celsius at Fukushima Daiichi Nuclear Power Plant

The frozen wall was a temporary solution for maximum 7 years and the time has run out anyway.

January 23, 2022

There was a problem at the Fukushima Daiichi Nuclear Power Plant where about 4 tons of liquid leaked out of a pipe that was injected into the ground to freeze the ground as part of the “frozen earth wall” that forms an “ice wall” around the buildings to prevent the inflow of underground water. Tokyo Electric Power Company (TEPCO) believes that a part of the pipe may have been damaged, and has decided to hurry to identify the location and repair it.

According to TEPCO, on January 16, the water level dropped in two of the four tanks that contain liquid at minus 30 degrees Celsius, which is used to freeze the ground around the buildings at the Fukushima Daiichi Nuclear Power Plant, and when they checked the area around the frost wall, they found a place where this liquid had accumulated.

The leaked liquid is a calcium chloride solution that acts as a “refrigerant” to freeze the ground, and it is estimated that about 4 tons of the liquid leaked from the water level of the tanks.

Even if the refrigerant leaks out, there is still a few months before the freezing wall itself starts to melt, so it is still functioning to prevent the inflow of groundwater, according to the report.

Tokyo Electric Power Company (TEPCO) believes that part of the pipe may have been damaged, and is hurrying to identify the location and repair it.

The freezing wall has been in operation since 2016, but last year some parts of the freezing wall experienced problems with the underground temperature remaining above 0 degrees Celsius, and TEPCO is investigating the cause and taking countermeasures.
https://www3.nhk.or.jp/news/html/20220123/k10013445291000.html?fbclid=IwAR06soHF-koVniJxnYVyMeADSSul3AXZTrGbMAW7folqVBtmfgk93cS5TLs

January 24, 2022 Posted by | Fuk 2022 | , , | Leave a comment

Steel Pipes to be Driven into Thawed Parts of Frozen Earth Wall at TEPCO’s Fukushima Daiichi Nuclear Power Plant

December 6, 2021
On December 6, Tokyo Electric Power Company (TEPCO) began to drive steel pipes into the ground to stop the inflow of underground water into the thawed part of the frozen soil barrier wall (about 1.5 km long) built underground around the No. 1 to No. 4 reactors at the Fukushima Daiichi Nuclear Power Plant (Okuma and Futaba towns, Fukushima Prefecture). Over the course of about a week, eight steel pipes with a diameter of 35 centimeters and a maximum length of six meters will be driven into the outside of the wall, creating a wall about four meters wide. If the water is not stopped, additional steel plates will be driven into the wall.
 According to TEPCO, the frozen soil wall is believed to be thawing at the intersection of the southwest side of Unit 4 and the underground tunnel for drainage. The temperature of the ground has been above zero since mid-September, and it has been confirmed that it has reached more than 10 degrees Celsius.
 The frost wall has been in operation since 2017 to prevent the inflow of groundwater into the reactor building, where melted nuclear fuel (debris) remains from the accident, and to reduce the generation of contaminated water. About 1,600 freezing pipes (30 meters long) driven into the ground are circulated with cooling liquid at 30 degrees below zero to freeze the surrounding soil.
https://www.tokyo-np.co.jp/article/147155?rct=national&fbclid=IwAR30nXaBUALO9eC4RHZkaRsXHg3j01jRmWd0RBkk4oF53UDmROD0Dk3YGNg

December 6, 2021 Posted by | Fukushima 2021 | , , | Leave a comment

Fukushima Daiichi Frozen Wall Section Fails

November 26, 2021

A section of the frozen wall at Fukushima Daiichi has melted. The portion south of unit 4 has had problems remaining fully frozen for years. Now TEPCO admits it has melted in recent weeks. This portion of the frozen wall has had issues for years. Recent changes to the nearby K drainage tunnel and a recently discovered crack may be redirecting water from an underground stream into the area of the frozen wall.

TEPCO found sections near the surface of the wall had fully melted. Puddled water was found nearby. The section is relatively small and didn’t impact the lower depths of the wall’s integrity.

TEPCO’s solution is to install steel piling sections between the K drainage canal and this section of the wall, hoping to deflect underground water. This steel wall will not be completely solid. Due to the nature of driving pilings into the ground, there could be gaps as wide as 10 cm.

Once the pilings are installed, TEPCO plans to monitor the area to make sure the problem has been resolved.

https://www3.nhk.or.jp/nhkworld/en/news/20211126_16/

December 5, 2021 Posted by | Fukushima 2021 | , , | Leave a comment

Part of the frozen soil barrier may have thawed at the Fukushima Daiichi Nuclear Power Plant. Steel pipes are being driven into the ground to stop groundwater flow.

Nov. 25, 2021
Tokyo Electric Power Company (TEPCO) announced on November 25 that it may have thawed part of the frozen soil barrier wall built around the No. 1 to No. 4 reactors at the Fukushima Daiichi Nuclear Power Plant (Okuma and Futaba towns, Fukushima Prefecture) to prevent the inflow of groundwater. The company has announced that it will try to stop the flow of water by driving several steel pipes into the wall. The project will start as early as early December, and if the temperature in the ground continues to rise, additional steel plates will be driven in.
 According to TEPCO, a thermometer installed in the ground at the intersection of the southwest side of Unit 4 and the underground tunnel for drainage confirmed that the temperature exceeded zero degrees Celsius in late August. Since late September, the temperature has sometimes been above 10 degrees Celsius. A spokesperson explained at a press conference that the groundwater level outside the wall was high, and water pressure may have created a water path.
 The steel pipe is 35 centimeters in diameter and up to six meters long. Nine of them will be driven into the ground outside the frozen soil wall, which may have thawed, to create a wall three to four meters wide.
 The freezing wall, which has been in operation since 2017, was built to prevent groundwater from flowing into the reactor building, where melted nuclear fuel (debris) remains from the accident, and to reduce the amount of contaminated water generated. The wall is about 1.5 kilometers long. About 1,600 freezing pipes (30 meters long) were driven into the ground. The freezing pipes are about 1,600 tubes (30 meters long) driven into the ground and circulated with a cooling liquid of 30 degrees Celsius to freeze the surrounding soil. (Kenta Onozawa)
https://www.tokyo-np.co.jp/article/144800

November 26, 2021 Posted by | Fukushima 2021 | , , | Leave a comment

Temperature of Fukushima Daiichi’s “frozen earth wall” rises again – TEPCO: “Function is being maintained.

Nov. 16
As a measure to reduce the amount of contaminated water from the Fukushima Daiichi Nuclear Power Plant, the temperature in the ground has been rising in a part of the “frozen soil wall” that freezes the ground around the buildings to prevent the inflow of underground water.
Tokyo Electric Power Company (TEPCO) has stated that the freezing wall is still functioning, but the cause of the problem is not known at this time.

The “frozen earth wall” is one of the measures to reduce the amount of contaminated water. Pipes are embedded around the buildings of the Fukushima Daiichi Nuclear Power Plant, and liquid at 30 degrees below zero is poured into the pipes and frozen, forming an “ice wall” that prevents underground water from flowing into the buildings.

TEPCO has installed thermometers in the “frozen earth wall” to measure the underground temperature, and it has been above 0 degrees Celsius in some areas on the mountain side of the Unit 4 reactor of the Fukushima Daiichi Nuclear Power Plant since mid-September, rising to 11.29 degrees Celsius on the 12th of last month.

After that, the temperature hovered around 5 degrees and dropped to 1.13 degrees on the 11th of this month, but it rose again to 8.88 degrees on the 14th, 9.65 degrees on the 15th, and 11.03 degrees on the 16th, exceeding 10 degrees for the first time in about a month.

The Tokyo Electric Power Company (TEPCO) investigated the inside of the frozen soil wall from the 10th to the 12th of this month, digging at a depth of about 2.8 meters where the temperature was rising, but could not find the cause.

The Tokyo Electric Power Company (TEPCO) has stated that “there has been no change in the level of groundwater and the function to control the inflow of water has been maintained.


https://www3.nhk.or.jp/lnews/fukushima/20211116/6050016369.html?fbclid=IwAR3Z6CT3b8ER4XjkTPda9E0gZ4SoyJimxDTR3WgZJ2sp69YzKlYgB3j0 Oig

November 18, 2021 Posted by | Fukushima 2021 | , | Leave a comment

Temperature rises over 10 degrees Celsius in some parts of the “frozen earth wall” to reduce contaminated water at Fukushima Daiichi Nuclear Power Plant

October 28, 2021

As a countermeasure to reduce the amount of contaminated water from the Fukushima Daiichi Nuclear Power Plant, it was found that the temperature of the ground in some parts of the “frozen soil wall”, which freezes the ground around the buildings to prevent the inflow of underground water, has been rising above 0 degrees Celsius since the middle of last month, reaching a maximum of 10 degrees Celsius. The Tokyo Electric Power Company (TEPCO) is investigating the cause of the problem, saying that it does not affect the function of the wall to prevent the inflow of underground water.

The “frozen earth wall” is one of the measures to reduce the amount of contaminated water. Pipes are embedded around the buildings of the Fukushima Daiichi Nuclear Power Plant, and liquid at 30 degrees below zero is poured into the pipes and frozen, forming an “ice wall” that prevents groundwater from flowing into the buildings.

The Tokyo Electric Power Company (TEPCO) has installed thermometers in the “frozen earth wall” to measure the underground temperature, and in some areas located on the mountain side of the No. 4 reactor at the Fukushima Daiichi Nuclear Power Plant, the temperature, which is usually below freezing, has been rising and has been above zero since the middle of last month.

The temperature in the area where the increase was confirmed was between 1 meter and 4 meters deep, and the temperature exceeded 10 degrees Celsius on some days.

The freezing wall is about 10 meters thick, and TEPCO has stated that there is no significant difference in the water level between the inside and outside of the wall, so there is no impact on its ability to control the inflow of groundwater.

It is possible that water leaked from cracks in the drainage channel that intersects the frozen soil wall and seeped into the frozen area, causing the temperature to rise.

https://www3.nhk.or.jp/news/html/20211028/k10013326291000.html?fbclid=IwAR3MBXXF1TlJxKAfYqkv0A5QS9Oddy0SJV86EvVul_HnWKcFSdaWmOH0Vp 8

October 29, 2021 Posted by | Fukushima 2021, Fukushima continuing | , | Leave a comment

Freezing wall to be used for longer period than expected, “trump card” of countermeasure against contaminated water at Fukushima Daiichi Nuclear Power Plant, without sufficient verification

 The frozen soil barrier wall at the Fukushima No. 1 Nuclear Power Plant of the Tokyo Electric Power Company (TEPCO) was built at a cost of 34.5 billion yen. Initially, TEPCO had planned to finish the work by 2021, but five years have passed since the freeze, and a large amount of contaminated water continues to be generated, with no prospect of even reaching zero. The ice wall, which will cost hundreds of millions of dollars to maintain every year, will enter long-term operation without sufficient verification. (Kenta Onozawa)


Freezing soil with cooling liquid, annual maintenance cost of billions of yen
The freezing wall was built to prevent groundwater from the mountains from entering the buildings where highly radioactive materials such as melted nuclear fuel (debris) remain after the accident. Freezing began in March 2004, and the entire area was frozen in nearly two years. The annual maintenance costs, including electricity for freezing, cost more than one billion yen when the system was first introduced, and TEPCO is bearing the cost.

From December 2007 to January 2009, there were a series of problems with cooling liquid leaking from a total of five frozen pipes. According to TEPCO, all of them are located under the road near the reactor building, and it is highly likely that the vibration of passing vehicles caused fatigue damage to the metal parts.


 TEPCO, which had not envisioned long-term operation of the plant, had been repairing problems only after they occurred, but from this year, it has set a frequency for replacement of parts and will prepare replacement parts in advance. A spokesperson said, “The frozen earth wall is effective and will be used continuously. However, from this year, the frequency of replacement will be set and replacement parts will be prepared in advance.


Groundwater through gaps, limited effect
 ”In March 2006, TEPCO announced that it would build a freeze-earth wall at the Fukushima Daiichi Nuclear Power Plant.
 In March 2006, TEPCO announced an estimate that the frozen soil wall prevented about 95 tons of groundwater per day from entering the buildings. Without the wall, the amount would have been 189 tons per day, and the company stressed that the amount had been halved.
 However, there is a lack of evidence for the estimate, as it was based on an evaluation of the period when there was little rainfall, and it does not distinguish between the effects of other measures, such as the pumping up of groundwater by sub-drainage wells around the building. Toyoshi Sarada, chairman of the Nuclear Regulation Authority (NRA), has declared that “the main role of groundwater countermeasures is to pump up the sub-drainage.
 At the press conference when the calculations were released, Naohiro Masuda, who was the chief decommissioning officer of TEPCO (now president of JNFL), stated clearly that “we will continue to verify” the effectiveness of the frost wall. However, the spokesman now avoids explaining, saying, “It is difficult to show the effects of individual measures.


Calls from the Regulatory Commission for an alternative plan
Initially, the government and TEPCO had set a goal of stopping the generation of contaminated water by around 2009. However, they still do not know where the groundwater is coming from.
 The amount of contaminated water, which was 490 tons per day in FY2003, was reduced to about 140 tons in FY2008, but zero was not achieved, and the goal was set back to 100 tons in 2013. TEPCO said, “We will continue with the current measures until 2013. After that, we are still studying.


 The cost of maintaining the frost wall will be covered by the electricity bills paid by consumers to TEPCO. In the regulatory commission’s study group, there is a strong opinion among experts that “from the viewpoint of cost-effectiveness, the frozen soil wall should be abandoned and steel plates or concrete walls should be embedded. In response to this opinion, TEPCO simply replied, “We are considering it,” and even 10 years after the accident, there is no end in sight to the contaminated water measures.

https://www.tokyo-np.co.jp/article/117551?fbclid=IwAR22EHyloXPo8UJUlsQrTBreHGz1ZNzT_z11KkUNStmn6p7x6LJ6Sp6uPgA

October 29, 2021 Posted by | Fukushima 2021 | , | Leave a comment

Fukushima Daiichi Frozen Wall Leaks

20200117_10_789878_L

Fukushima nuclear plant’s frozen wall leaks

Jan. 17, 2020

Tokyo Electric Power Company says coolant has seeped out from an underground frozen soil wall built around its crippled Fukushima Daiichi nuclear plant.

The frozen soil wall came into operation four years ago. It was built to keep groundwater from flowing into reactor buildings. They were damaged by the March 2011 earthquake, tsunami and subsequent nuclear meltdowns.

The utility firm, TEPCO, says it found coolant leaking at three locations from components that connect pipes in the wall. The company had noticed a reduction in coolant in its tank earlier this month and was searching for the cause.

TEPCO says it believes 20,000 of 1.1 million liters of the coolant has leaked, but that this will not affect the operation of the wall.

The company says it will replace the components in the wall and repair another leak that was found in December.

https://www3.nhk.or.jp/nhkworld/en/news/20200117_10/

hjlmmùùFukushima Daiichi Nuclear Power Station is seen in Okuma, Fukushima Prefecture, in this photo taken from a Mainichi Shimbun helicopter in August 2019.

Four coolant leaks found in Fukushima nuke plant ‘ice wall’ pipes

January 17, 2020

TOKYO — Coolant has been found leaking from pipes in the underground wall of frozen soil surrounding reactor buildings at the tsunami-ravaged Fukushima Daiichi Nuclear Power Station at four locations, its operator said.

According to Tokyo Electric Power Company Holdings, Inc. (TEPCO), the coolant liquid contains calcium chloride, commonly used as a snow-melting agent, and is not an environmental contaminant.

The utility has confirmed that a total of about 20 cubic meters of the coolant has leaked from the pipes. Though the coolant supply to the leaking pipes has been halted, TEPCO does not expect the ice wall to suffer any loss of function. The pipes concerned are between the plant’s No. 2 and No. 3 reactor buildings.

TEPCO noticed the problem in late 2019 when the volume in a coolant tank dropped abnormally. Workers examined the ice wall piping and found leaks in the joints. The company is poised to investigate the cause of the leak and replace the problematic parts.

The utility started the operation of the underground wall of frozen soil at the stricken complex in 2016. Coolant chilled to minutes 30 degrees Celsius is circulated through buried pipes, freezing the soil around the reactor buildings to prevent ground water from flowing into the structures

https://mainichi.jp/english/articles/20200117/p2a/00m/0na/022000c

January 21, 2020 Posted by | Fukushima 2020 | , , | Leave a comment

Fukushima nuclear plant owner apologizes for still-radioactive water

feb 2017.jpg
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.

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