Fuel removal from Fukushima reactor may be delayed

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June 29, 2018
The operator of the damaged Fukushima Daiichi nuclear power plant says work to remove spent nuclear fuel from a cooling pool at one of its reactors may be delayed.
A total of 566 fuel units remain in the cooling pool at the No.3 reactor, which suffered a meltdown in 2011. Tokyo Electric Power Company, or TEPCO, planned to start removing the fuel as early as this autumn, as part of the decommissioning of the nuclear complex.
But on Thursday, TEPCO revealed the control board of a crane used in the removal malfunctioned during a test run last month. It blamed a voltage error and said the board will be replaced.
The company said the test run may be delayed by one or 2 months, pushing back the start date for fuel removal.
TEPCO’s chief decommissioning officer, Akira Ono, says he takes the glitch seriously as it shows key equipment was not handled properly.
He says that although safety must come first, his team still aims to stick to the original timetable and start the removal of nuclear fuel by around the middle of the current fiscal year, which ends in March next year.
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TEPCO prepares to remove fuel from damaged reactor

 

May 28, 2018
The operator of the damaged Fukushima Daiichi nuclear power plant has started laying the groundwork to retrieve fuel from one of the plant’s reactor buildings. It’s a crucial step toward scrapping the complex.
 
Tokyo Electric Power Company began the work on Monday to move 615 fuel rod units from a storage pool on the top floor of the No. 2 reactor to a more secure location.
 
The No. 2 reactor is one of 3 at the plant that melted down in the 2011 accident. Radiation levels inside the reactor building remain high.
 
TEPCO will open a hole measuring 5 by 7 meters in the building’s wall and send a robot through it to measure radiation levels inside.
 
A section of the wall will be divided into 29 blocks, each with a handle to facilitate its removal.
 
From a control room some distance from the reactor building, TEPCO officials will remotely operate a machine to remove the blocks.
 
The work is expected to continue until mid-June.
 
The plant operator will measure radiation levels before deciding how to retrieve the fuel rods. The company plans to start retrieving the fuel in fiscal 2023.
 
TEPCO official Hiroshi Noda says that although the decommissioning work for the No. 2 reactor has just started, it’s a major step forward.
 
He says the company will make sure that the work will have no impact on the environment.

Fukushima dome roof takes shape, but radiation remains high

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Construction continues on a domed roof on top of the No. 3 reactor building at the Fukushima No. 1 nuclear power plant.
High radiation levels are still limiting recovery work at the Fukushima No. 1 nuclear plant, a stark reality that reporters saw firsthand when they observed efforts to remove risk factors there.
Media representatives were invited into the plant in early December to see construction work, with the building of a domed roof over the No. 3 reactor building as the main focus.
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However, they were only allowed to stay on top of the roof for 20 minutes due to high radiation levels.
The roof is being put together directly above the storage pool for spent fuel. The dome is designed to prevent the spewing of radioactive materials when the fuel is actually removed from the pool.
The original roof of the No. 3 reactor building was severely damaged by a hydrogen explosion in the days following the March 11, 2011, Great East Japan Earthquake and tsunami, which led to the crippling of the Fukushima No. 1 plant.
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Spent fuel still remains in the storage pools located on the top floors of the No. 1 to No. 3 reactor buildings.
Plans call for removing the spent fuel first from the No. 3 reactor building.
Although the dome will help prevent the spread of radioactive materials, building parts and other debris as well as some equipment have still not been completely removed from the storage pool, which holds 566 fuel rods.
The collapsed roof and walls were removed to allow for the construction of the domed roof, which began in the summer. The domed roof is about 17 meters high, and a crane was also installed under it in November.
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Plans call for the removal of the spent fuel from the No. 3 building to begin in the middle of the next fiscal year.
Internal radiation exposure levels were measured before media representatives headed to the No. 3 reactor building. They were also required to don protective clothing as well as a partial face mask covering the mouth and nose from about 100 meters from the building.
Radiation levels close to the building were 0.1 millisieverts per hour.
An elevator installed into the scaffolding next to the reactor building took the media representatives to the roof, which had been covered with metal plates.
The so-called operating floor looked like any other newly constructed building roof, a sharp contrast to the twisted metal parts that covered the building shortly after the nuclear accident.
Tokyo Electric Power Co., the plant’s operator, captured video footage from within the reactors for the first time in July. Debris that appears to be melted nuclear fuel was found in various parts of the containment vessel.
To the south of the No. 3 reactor building stands the No. 4 reactor building, from where all the spent nuclear fuel has been removed.
To the north is the No. 2 reactor building, which avoided a hydrogen explosion. Beyond the building, cranes and other large equipment are working in preparation for the removal of debris from the No. 1 reactor building.
TEPCO officials cautioned media representatives about standing too long right next to the storage pool, which could be seen located about six meters below the roof. Debris was found within the pool while insulating material floated on the pool surface.
The radiation level near the pool was 0.68 millisieverts per hour. While that was a major improvement from the 800 millisieverts per hour recorded in the immediate aftermath of the nuclear accident close to seven years ago, it was still too high to allow for a stay of longer than 20 minutes.

Tepco starts installing device to prepare for fuel removal from reactor 3 cooling pool at Fukushima No. 1

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The building housing reactor 3 at the crippled Fukushima No. 1 plant is seen Sunday as work begins to install equipment to remove fuel assemblies from the unit’s storage pool
FUKUSHIMA – Tepco on Sunday began installing equipment to be used for removing fuel from the storage pool for reactor 3 at the Fukushima No. 1 nuclear plant.
The equipment, weighing 72 tons, was lifted by two large cranes.
The storage pool, located in the reactor building on a floor 36 meters above ground level, holds 566 spent and unused nuclear fuel assemblies.
Tokyo Electric Power Company Holdings Inc. plans to begin removing the fuel from the pool by the middle of next year.
The installation work was originally slated to start Saturday but was postponed due to strong winds.
The fuel assemblies are to be placed in sturdy containers that will be tightly sealed to block emissions of strong radiation.
The work will be conducted in the water-filled pool, and then the containers will be lowered to the ground using a different crane and transferred to another pool some distance from the reactor, where they will be stored.
The building housing the No. 3 reactor was heavily damaged by a hydrogen explosion shortly after the power station was knocked out by the tsunami following the magnitude 9 earthquake in March 2011.
After debris from the blast was removed from the upper part of the No. 3 reactor, Tepco started work in late July this year to install a cover on top of the reactor to shield the fuel-removing equipment from weather damage and prevent radioactive materials from spreading.
The crane to be used for lowering the fuel containers to the ground is slated to be installed in the upper part of the reactor on Nov. 20.

Multiple challenges remain to Fukushima nuclear cleanup

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This Sept. 4, 2017 aerial photo shows Fukushima Dai-ichi nuclear power plant reactors, from bottom at right, Unit 1, Unit 2 and Unit 3, in Okuma, Fukushima Prefecture, northeastern Japan. The three reactors that had meltdowns together have 1,573 units of mostly used nuclear fuel rods that are still inside and must be kept cool in pools of water. They are considered among the highest risks in the event of another major earthquake, because the pools are uncovered. The plant operator, Tokyo Electric Power Co. or TEPCO, plans to begin removing the rods from reactor unit 3 in the fiscal year beginning next April 1. However, the latest roadmap delays removal of the rods from units 1 and 2 for three years until fiscal 2023, because further decontamination work and additional safety measures are needed.

Japan’s government approved on Tuesday, Sept. 26, 2017 a revision to the decommissioning plan for the Fukushima nuclear plant, delaying by two more years the removal of radioactive fuel rods in two of the three reactors damaged in the 2011 disaster. It still plans for melted fuel to be removed starting in 2021, but the lack of details about the duration raises doubts if the cleanup can be completed within 40 years. Kyodo News via AP, File)


TOKYO – Japan’s government approved a revised road map Tuesday to clean up the radioactive mess left at the Fukushima nuclear power plant after it was damaged beyond repair by an earthquake and tsunami in 2011. Decommissioning the damaged reactors is an uncertain process that is expected to take 30 to 40 years.

A look at some of the challenges:

THE FUEL RODS

The three reactors that had meltdowns together have 1,573 units of mostly used nuclear fuel rods that are still inside and must be kept cool in pools of water. They are considered among the highest risks in the event of another major earthquake that could trigger fuel rods to melt and release massive radiation due to loss of water from sloshing or structural damage because the pools are uncovered. The plant operator, Tokyo Electric Power Co., or TEPCO, plans to begin moving the rods from reactor Unit 3 in the fiscal year beginning April 1.


However, the latest road map delays removal of the rods from units 1 and 2 for three years until fiscal 2023, because further decontamination work and additional safety measures are needed. Ironically, because the building housing reactor 3 was more heavily damaged, it is easier to remove that unit’s fuel rods. The fuel rods will be moved to a storage pool outside the reactors, and eventually sent for long-term storage in what are known as dry casks.

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THE MELTED FUEL

By far the hardest part of decommissioning Fukushima will be removing the fuel that melted and presumably spilled out of the reactor cores. In July, an underwater robot for the first time captured images inside the primary containment chamber of Unit 3. They showed a large number of solidified lava-like rocks and lumps on the chamber’s floor, believed to be melted fuel mixed with melted and mangled equipment and parts of the structure.

The search for melted fuel in units 1 and 2 has so far been unsuccessful. The water level is lower, so crawling robots have been tried, but they have been obstructed by debris as well as extremely high radiation levels. Despite the unknowns about the melted fuel and debris and their whereabouts, the road map calls for finalizing the removal method in 2019, and starting actual removal at one of the reactors in 2021. The government-funded International Research Institute for Nuclear Decommissioning is developing robots and other technology to carry out the work.

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CONTAMINATED WATER

TEPCO has treated and stored a massive amount of radioactive water — about 800,000 tons — and the volume is growing every day. Cooling water leaks out of the damaged reactors and mixes with groundwater that seeps into the basements of the reactor building, increasing the amount of contaminated water. The utility has managed to halve the volume to 200 tons per day by pumping up groundwater via dozens of wells dug upstream from the reactors, as well as installing a costly “ice wall” by freezing the ground to block some of the water from coming in and going out.

The water is stored in hundreds of tanks that cover much of the plant property. They get in the way of decommissioning work and pose another risk if they were to spill out their contents in another major earthquake or tsunami. After treatment, the water still contains radioactive tritium, which cannot be removed but is not considered harmful in small amounts. Experts say controlled release of the water into the ocean is the only realistic option, but TEPCO has not moved forward with that plan because of opposition from fishermen and residents who fear a negative image and possible health impact.

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RADIOACTIVE WASTE

Japan has yet to develop a plan to dispose of the highly radioactive waste that will come out of the Fukushima reactors. Under the road map, the government and TEPCO will compile a basic plan during fiscal 2018. Managing the waste will require new technologies to compact it and reduce its toxicity. Finding a storage site for the waste seems virtually impossible, as the government has not been able to find a site even for the normal radioactive waste from its nuclear power plants. The prospect raises doubts about whether the cleanup can really be completed within 40 years.

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http://www.miamiherald.com/news/business/article175387901.html

Spent Nuclear Fuel Removal at Fukushima Plant Delayed Again

Japan muddles on with Fukushima’s melted and “spent” fuel. The three year delay for emptying the reactors “spent” irradiated nuclear fuel into a dry cask storage runs the risk of another major earthquake causing a loss of cooling in the pools without containments and another major release of radiation. Plans for removing the melted reactor cores from Units 1, 2 and 3 still defied by inability to locate it.

 

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Fukushima Nuclear Plant Scrapping Plan Faces Another Delay

A key decision in decommissioning the crippled Fukushima Daiichi nuclear plant is being delayed. The Japanese government and operator made the announcement on Tuesday while giving an update on the roadmap for scrapping the plant.

In their first such update in 2 years, officials said they will postpone their decision on the method for removing molten fuel debris by one year, until fiscal 2019.

Experts believe that when the plant went into triple meltdown in 2011, most of the fuel inside the reactors collected at the bottom of containment vessels. They still don’t know the exact location, but possible molten fuel debris was caught on camera in July. The removal of this debris is considered the most challenging part of the plant’s decommissioning.

Originally, officials considered filling the containment vessels with water to block radiation while removing the debris. But now, they say they’re leaning towards a method called dry removal.

Experts say that method comes with safety challenges. “Because the containment vessel will not be filled with water, there is a possibility that radioactive substances may leak and get dispersed,” says Hosei University Visiting Professor Hiroshi Miyano.

Officials also gave an update on plans for the removal of spent nuclear fuel rods in 2 of the plants reactors. The rods are in storage pools and won’t be removed until fiscal 2023. That’s 3 years later than planned. The official timeline for scrapping the plant remains the same — about 30 to 40 years in total.

https://www3.nhk.or.jp/nhkworld/nhknewsline/nuclearwatch/fukushimanuclearplantscrapping/

Spent nuclear fuel removal at Fukushima plant pushed back again

n-roadmap-a-20170927-870x438Cabinet ministers attend a meeting at the Prime Minister’s Office on Tuesday to discuss a delay in the road map for decommissioning the Fukushima No. 1 nuclear power plant.

 

The government and Tokyo Electric Power Company Holdings Inc. decided Tuesday to further delay the removal of spent nuclear fuel left near two of the three reactors that suffered meltdowns at the Fukushima No. 1 nuclear plant.

In the road map for decommissioning the plant, revised for the fourth time since it was first crafted in 2011, highly radioactive spent fuel will be extracted from the cooling pools of reactors 1 and 2 starting in fiscal 2023 instead of fiscal 2020.

The decision marks the third delay for the removal plan, with the last adjustment coming in June 2015. The government said new technical issues and the need to take safety precautions led to the latest change.

The cleanup process is set to be completed in around 30 to 40 years.

Spent fuel removal at the plant’s reactor 3 will go ahead in fiscal 2018 as planned, having already been pushed back earlier this year.

In the decommissioning process, the removal of fuel rod assemblies from the spent fuel pools in reactor buildings is one of the key steps before extracting melted fuel debris. Reactors 1, 2 and 3 suffered core meltdowns following the March 2011 earthquake and tsunami disaster.

The removal of melted fuel debris has also been delayed, with an extraction plan set to be decided in fiscal 2019, pushed back from the first half of fiscal 2018.

Despite the delay in finalizing specific methods, the road map maintains a 2021 start for debris extraction, the most challenging part of the decommissioning process.

A method currently considered feasible by the government involves removing debris from the sides of the reactors after partially filling them with water.

The road map newly sets the goal of cutting the amount of underground water at the plant to address contaminated water buildup. Underground water — which gets mixed with accumulated radioactive water generated in the process of cooling the damaged reactors — is to be cut to around 150 tons per day in 2020 from the current 200 tons.

The road map does not mention a specific schedule for the disposal of processed water that still contains radioactive tritium.

The plan was first crafted in December 2011 in the wake of the meltdowns, the world’s worst nuclear crisis since the 1986 Chernobyl disaster.

Attempts have been made to confirm the situation inside the damaged reactors using specialized robots. A survey in July this year captured for the first time images of what is likely to be melted nuclear fuel at the bottom of reactor 3.

Isamu Kaneda, deputy mayor of the Fukushima Prefecture town of Futaba, expressed regret over the delay.

The town’s rebuilding depends on the development of decommissioning. It’s unfortunate,” Kaneda said. “But at the same time, the decommissioning process is an unprecedented project. It needs to be conducted carefully, so we can’t just ask them to speed it up.”

https://www.japantimes.co.jp/news/2017/09/26/national/spent-nuclear-fuel-removal-fukushima-plant-pushed-back/#.WcqxGxdx3rc

Spent nuclear fuel removal at Fukushima plant to be delayed again

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TOKYO (Kyodo) — The government and Tokyo Electric Power Company Holdings Inc. decided Tuesday to delay again the start of removing spent nuclear fuel left near two of the three reactors which suffered a meltdown at the Fukushima complex.

In the road map for decommissioning the Fukushima Daiichi plant, revised for the fourth time since it was first crafted in December 2011, highly radioactive spent nuclear fuel will be extracted from the Nos. 1 and 2 units’ cooling pools starting in fiscal 2023 instead of fiscal 2020.

It is the third time that the schedule for spent fuel removal has been pushed back at the Nos. 1 and 2 reactors, with the previous postponement taking place in June 2015. The government said new technical issues and the need to take safety precautions led to the latest schedule change.

The cleanup process is to be completed in around 30 to 40 years.

For the No. 3 reactor at the Fukushima plant, the schedule to remove spent nuclear fuel during fiscal 2018 is unchanged after having already been pushed back earlier this year.

In the decommissioning process, taking out fuel rod assemblies from the spent fuel pools inside reactor buildings is one of the key steps before extracting melted fuel debris from the Nos. 1 to 3 reactors, all of which suffered core meltdowns following the March 2011 earthquake and tsunami disaster.

The schedule for extraction of the melted fuel debris at the reactors was also revised, with the determination of a specific approach to remove the debris to be made in fiscal 2019, rather than in the originally planned first half of fiscal 2018.

Despite the delay in finalizing specific methods, the road map kept the start of the debris extraction, the most challenging part of the decommissioning process, at 2021.

A method currently considered feasible by the government is debris removal from the side of the three crippled reactors by partially filling them with water.

The road map newly sets the goal of cutting the amount of underground water at the plant to address contaminated water buildup at the site. Underground water, which gets mixed with accumulated radioactive water generated in the process of cooling the damaged reactors — is to be cut to around 150 tons per day in 2020 from the current 200 tons.

It did not mention a specific schedule for disposal of processed water that still contains radioactive tritium.

The road map was first crafted in December 2011 in the wake of the 2011 disaster which triggered at the Fukushima plant the world’s worst nuclear crisis since the 1986 Chernobyl disaster.

Attempts have been made to confirm internal conditions of the damaged reactors using robots. A survey robot captured images of what is likely to be melted nuclear fuel at the bottom of the No. 3 reactor for the first time in July this year.

http://mainichi.jp/english/articles/20170926/p2g/00m/0dm/064000c