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Removal of fuel in pool at Fukushima’s melted reactor begins

WireAP_3934906a98594efcb9b18a9003f893ac_12x5_992
A Tokyo Electric Power Co. worker explains the operation at Unit 3 of Fukushima nuclear plant, in Okuma, Fukushima Prefecture, northeastern Japan Monday. April 15, 2019. The operator of the tsunami-wrecked nuclear plant has begun removing fuel from a cooling pool at one of three reactors that melted down in the 2011 disaster, a milestone in the decades-long process to decommission the plant.

 

By mari yamaguchi
April 15, 2019
The operator of the tsunami-wrecked Fukushima nuclear plant began removing fuel Monday from a cooling pool at one of three reactors that melted down in the 2011 disaster, a milestone in what will be a decades-long process to decommission the facility.
Tokyo Electric Power Co. said workers started removing the first of 566 used and unused fuel units stored in the pool at Unit 3. The fuel units in the pool located high up in reactor buildings are intact despite the disaster, but the pools are not enclosed, so removing the units to safer ground is crucial to avoid disaster in case of another major earthquake similar to the one that caused the 2011 tsunami.
TEPCO says the removal at Unit 3 will take two years, followed by the two other reactors, where about 1,000 fuel units remain in the storage pools.
Removing fuel units from the cooling pools comes ahead of the real challenge of removing melted fuel from inside the reactors, but details of how that might be done are still largely unknown. Removing the fuel in the cooling pools was delayed more than four years by mishaps, high radiation and radioactive debris from an explosion that occurred at the time of the reactor meltdowns, underscoring the difficulties that remain.
Workers are remotely operating a crane built underneath a jelly roll-shaped roof cover to raise the fuel from a storage rack in the pool and place it into a protective cask. The whole process occurs underwater to prevent radiation leaks. Each cask will be filled with seven fuel units, then lifted from the pool and lowered to a truck that will transport the cask to a safer cooling pool elsewhere at the plant.
The work is carried out remotely from a control room about 500 meters (yards) away because of still-high radiation levels inside the reactor building that houses the pool.
“I believe everything is going well so far,” plant chief Tomohiko Isogai told Japanese public broadcaster NHK. “We will watch the progress at the site as we put safety first. Our goal is not to rush the process but to carefully proceed with the decommissioning work.”
About an hour after the work began Monday, the first fuel unit was safely stored inside the cask, TEPCO spokesman Takahiro Kimoto said. Monday’s operation was to end after a fourth unit is placed inside the cask, he said. No major damage was found on the fuel unit Monday, but plant officials will closely examine if there are any pinholes or other irregularities, Kimoto said.
The removal, however, raises a storage capacity concern at the plant because the common pool, where fuel from the Unit 3 pool heads to, already has 6,000 fuel units and is almost full. Kimoto said TEPCO has made room at the common pool for the incoming fuel by moving years-old and sufficiently cooled fuel into dry casks for safer, long-term storage, though further details are being worked out.
In 2014, TEPCO safely removed all 1,535 fuel units from the storage pool at a fourth reactor that was idle and had no fuel inside its core when the March 11, 2011, earthquake and tsunami occurred.
Robotic probes have photographed and detected traces of damaged nuclear fuel in the three reactors that had meltdowns, but the exact location and other details of the melted fuel are largely unknown. Removing fuel from the cooling pools will help free up space for the subsequent removal of the melted fuel, though details on how to gain access to it have yet to be decided.
Experts say the melted fuel in the three reactors amounts to more than 800 tons, an enormous amount that is more than six times that of the 1979 accident at Three Mile Island, where one reactor had a partial core melt.
In February, a remote-controlled robot with tongs removed pebbles of nuclear debris from the Unit 2 reactor but was unable to remove larger chunks, indicating a robot would need to be developed that can break the chunks into smaller pieces. Toshiba Corp.’s energy systems unit, which developed the robot, said the findings were key to determining the proper equipment and technologies needed to remove the melted fuel, the most challenging part of the decommissioning.
TEPCO and government officials plan to determine methods for removing the melted fuel from each of the three damaged reactors later this year so they can begin the process in 2021.

April 23, 2019 Posted by | fukushima 2019 | , , , | Leave a comment

TEPCO to start removing fuel at Fukushima’s No. 3 reactor

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Workers lower the last part of a semi-cylindrical covering on top of the No. 3 reactor building.
April 12, 2019
The operator of the crippled Fukushima No. 1 nuclear power plant will start removing nuclear fuel from the No. 3 reactor as early as next week through equipment controlled remotely due to high radiation levels inside the building.
This will mark Tokyo Electric Power Co.’s first attempt to remove spent fuel from one of the three reactors that experienced a meltdown during the 2011 nuclear accident.
All spent fuel has already been removed from the No. 4 reactor.
TEPCO workers will use remote control to remove nuclear fuel assemblies kept in the pool on the upper floors of the No. 3 reactor building.
Utility officials acknowledge that the process will not be easy, as they have no experience conducting such a dangerous task remotely.
The 566 nuclear fuel assemblies in the storage pool will be removed under a plan expected to take two years to complete.
TEPCO wants to remove the assemblies as quickly as possible owing to concerns that another major earthquake or tsunami could further damage the reactor building and equipment. The No. 3 reactor will also serve as a test case for eventually removing spent nuclear fuel from the No. 1 and No. 2 reactor buildings.
Under the plan, workers will be stationed in a control room about 500 meters from the reactor building and use remote control equipment while observing the process through monitors.
Each nuclear fuel assembly will be lifted and transferred to a special transport container that can hold up to seven such assemblies in water. The container will then be carried out of the reactor building by crane, which will then lower the container outside of the building to a trailer about 30 meters below at ground level.
As a hydrogen explosion blew off the roof of the No. 3 reactor building in the wake of the 2011 nuclear accident, a semi-cylindrical copper covering has been placed over the building to prevent radioactive materials from spreading when the spent nuclear fuel is being removed.
All 1,535 nuclear fuel assemblies at the No. 4 reactor building were removed by the end of 2014. Radiation levels were comparatively low so workers could enter the building to work on the removal.
A TEPCO official in charge of the process called the removal at the No. 4 reactor “normal operating procedures,” but admitted that remote control operations added a new dimension of difficulty.
The utility has experienced problems with the crane and other equipment to be used at the No. 3 reactor.
Under TEPCO’s plan compiled shortly after the nuclear accident, all spent nuclear fuel was to have been removed from all four reactors by the end of fiscal 2021.
“We do not believe the process will proceed with zero problems,” said Akira Ono, president of the Fukushima Daiichi Decontamination and Decommissioning Engineering Co.
The work at the No. 3 reactor will serve as a model for a similar process planned for the No. 1 and No. 2 reactor buildings to start in fiscal 2023.
Government and TEPCO officials have said they will consider a detailed plan for removing spent nuclear fuel from those two buildings after reviewing the work done at the No. 3 reactor building.
The two other reactor buildings present different hurdles for workers.
The top floor of the No. 1 reactor building is covered with debris from a collapsed ceiling and damaged crane, the removal of which has proved difficult. Workers have also confirmed that the lid on top of the containment vessel has shifted, meaning radiation levels inside the building are likely even higher than in the No. 3 reactor building.
It thus remains to be seen if the same equipment to be used for the No. 3 reactor can be used for the No. 1 building. To prevent leaking of radioactive materials, the lid for the containment vessel will first have to be moved back into place.
While the No. 2 reactor building did not suffer major structural damage, large amounts of radioactive materials are believed to be trapped inside the building, meaning radiation levels are also very high there.
The level at the top floor is so high that any worker remaining there for one hour would quickly exceed the annual radiation exposure level. After decontamination, the upper part of the No. 2 reactor building will have to be taken apart to remove the spent fuel. However, this poses the major problem of preventing the spewing of radioactive materials during that process.
“To be honest, it will be difficult to say that no problems will emerge that will force a change in plans,” said Toyoshi Fuketa, chairman of the Nuclear Regulation Authority.

April 14, 2019 Posted by | fukushima 2019 | , , | 1 Comment

356 microsieverts / hr at R #3 on Feb 9th 2016

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Credit to Ray Masalas

August 28, 2016 Posted by | Fukushima 2016 | , , | Leave a comment

Shikoku Electric restarts reactor under post-Fukushima regulations

Ikata nuclear power plant in Ehime Prefecture, is restarted.

After the Tepco Fukushima Daiichi earthquake/tsunami disaster and the Kumamoto recent earthquake, it is to be wondered what Japan has learned?

The Ikata nuclear power plant is located on the Hinagu fault zone and Futagawa fault zone, themselves extension of Japan’s largest active fault “Median Tectonic Line”.

In case of any accident, for the residents living on Sadamisaki Peninsula evacuation would be only possible by boat to Kyushu Island, such evacuation would be therefore difficult, even impossible.

Unless there would be a Japanese Moses to open the sea, such evacuation plan should be referred to as an escape from reality.

ehime npp

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The Ikata Nuclear Power Plant in Ikata, Ehime Prefecture

MATSUYAMA, Japan (Kyodo) — Shikoku Electric Power Co. restarted a reactor at its Ikata power plant in western Japan on Friday, making it the fifth unit reactivated under tougher regulations set following the 2011 Fukushima nuclear disaster.

The No. 3 reactor at the plant in Ehime Prefecture is the only restarted unit in Japan that runs on uranium-plutonium mixed oxide, or MOX, fuel, as a court ordered Kansai Electric Power Co. in March to suspend two reactors at its Takahama plant after they resumed operations earlier this year, citing safety concerns.

MOX fuel, created from plutonium and uranium extracted from spent fuel, is a key component of the nuclear fuel recycle program pursued by the nuclear power industry and the government.

The government aims to bring reactors back online after the Fukushima crisis led to a nationwide halt of nuclear plants, as it plans to have nuclear power account for 20 to 22 percent of the country’s total electricity supply in 2030 to cut greenhouse emissions and lower imported fuel costs.

The Ikata unit is expected to reach criticality, or a state of sustained nuclear chain reaction, on Saturday and begin generating and transmitting electricity on Monday before resuming commercial operation in early September for the first time since it was halted in April 2011 for regular inspection.

“We will take steps toward criticality and resumption of power generation with priority on ensuring safety,” Shikoku Electric President Hayato Saeki said in a statement on Friday.

Meanwhile, around 70 residents and others opposing the reactor restart gathered around the seaside plant early Friday morning, chanting slogans such as “Don’t contaminate the Seto Inland Sea,” and “Stop the nuclear plant.”

Junko Saima, a 72-year-old woman from Yawatahama, adjacent to the town hosting the plant, which is located on one side of a narrow peninsula, said, “I am nervous that some kind of accident may occur.”

Opponents are concerned about the effectiveness of government-prepared evacuation plans in case of an accident and about potential major earthquakes that are not taken into account in the plans, while proponents are hailing the resumption as it could bring economic benefits.

The restart follows the reactivation of two reactors at Kyushu Electric Power Co.’s Sendai plant in Kagoshima Prefecture last year and the brief run of the Nos. 3 and 4 units at Kansai Electric’s Takahama complex in Fukui Prefecture.

The mayor of Ikata town and the governor of Ehime Prefecture have already given their consent to restart the No.3 reactor after regulators approved its restart in July last year.

In June, Shikoku Electric loaded nuclear fuel at the power plant eyeing to reboot it on July 26. However, reactivation was postponed due to problems with the reactor’s cooling system.

A group of local residents filed a suit in May seeking an injunction to halt the restart arguing that a series of earthquakes that have hit nearby Kyushu Island in April could trigger quakes along the median tectonic line running close to the Ikata reactor.

The plant is about 170 kilometers east of Kumamoto Prefecture, the epicenter of the quakes.

Meanwhile, in Kagoshima, new Gov. Satoshi Mitazono is planning to ask Kyushu Electric to suspend the two reactivated reactors at the Sendai plant to double-check any safety impact on the units from the powerful earthquakes that hit neighboring Kumamoto in April.

http://mainichi.jp/english/articles/20160812/p2g/00m/0dm/035000c

August 12, 2016 Posted by | Japan | , , , , | Leave a comment

Tepco investigated equipment hatch of Reactor 3 PCV / “Next time, use robot with a smartphone”

2-Video-Tepco-investigated-equipment-hatch-of-Reactor-3-PCV-Next-time-use-robot-with-a-smartphone-800x500_c

On 9/9/2015, Tepco investigated the equipment hatch of PCV 3 (Reactor 3 PCV) with a portable camera.

They reported the hatch is not leaking coolant water from the inside of PCV 3, nor was damaged however the floor was wet and didn’t confirm where the water was leaking.

None of the atmospheric dose or nuclide analysis data was released. On the other hand, the video shows the white noise caused by extremely high level of radiation.

Considering what they have found in this investigation, Tepco is to decide to send a remote-controlling robot for the next phase. The robot is planned to carry a “smartphone camera” for some reason.

The plan image of the new robot to investigate inside PCV 3. A smartphone is used as its camera.

Video-Tepco-investigated-equipment-hatch-of-Reactor-3-PCV-Next-time-use-robot-with-a-smartphone

http://www.tepco.co.jp/nu/fukushima-np/handouts/2015/images/handouts_150909_12-j.pdf

http://photo.tepco.co.jp/date/2015/201509-j/150909-03j.html

Source: Fukushima Diary

http://fukushima-diary.com/2015/09/video-tepco-investigated-equipment-hatch-of-reactor-3-pcv-next-time-use-robot-with-a-smartphone/

September 11, 2015 Posted by | Japan | , | Leave a comment

Tepco readies to install unit 3 cover

From World Nuclear News, a pro-nuclear website

Fukushima Daiichi 3 cover preparations - aug 13 2015

The installation of a protective cover over unit 3 of the damaged Fukushima Daiichi plant in Japan can start as soon as the removal of rubble from the reactor building is completed, Tokyo Electric Power Company (Tepco) said.

Plans were announced in November 2012 for a cover to be constructed to encase the unit’s damaged reactor building, protecting it from the weather and preventing any release of radioactive particles during decommissioning work.

The section of the reactor building that sheltered the service floor of unit 3 was wrecked by a hydrogen explosion three days after the tsunami of March 2011 – leaving the fuel pond exposed and covered by debris including many twisted steel beams.

The fabrication of the cover has been under way since November 2013 at the Onahama works in Iwaki city. It has been made in sections so that once it is transported to Fukushima Daiichi, the time to assemble it can be shortened and the radiation exposure to the workers on site can be significantly reduced, Tepco said.

A separate structure will be built to facilitate the removal by crane of used fuel from the storage pool. This 54-metre-tall structure will include a steel frame, filtered ventilation and an arched section at its top to accommodate the crane. Measuring 57 metres long and 19 metres wide, it will not be fixed to the reactor building itself, but will be supported on the ground on one side, and against the turbine building on the other.

On 2 August, Tepco announced that it had removed the fuel handling machine, the largest remaining piece of rubble, from the unit’s used fuel pool at the top of its reactor building. Its removal followed months of preparation and clears the way for the remaining rubble and the used fuel in the storage pool to be removed.

The assembly of the protective cover over unit 3 will start once all the rubble is removed.

Tepco said there are a total of 566 fuel assemblies inside the unit’s pool and the cover will prevent radioactive substances from scattering during their removal.

The fuel removed from unit 3 will be packaged for transport the short distance to the site’s communal fuel storage pool, although it will need to be inspected and flushed clean of dust and debris.

Source: World Nuclear News

http://www.world-nuclear-news.org/RS-Tepco-readies-to-install-unit-3-cover-1308155.html

August 14, 2015 Posted by | Japan | , | Leave a comment

Removal of debris in reactor 3 spent fuel storage to start

Workers at the Fukushima Daiichi nuclear power plant on Sunday will start the removal of a fuel exchanger inside the Number 3 reactor building. The 20-ton device fell into the fuel pool during the 2011 disaster.

The device has since been a major obstacle for workers at Tokyo Electric Power Company in the start of removal of extremely radioactive rubble left in the storage pool. 566 fuel rods remain inside the spent fuel pool.

Workers cannot directly take part in the process as the site is highly radioactive. The work will require 2 remote-controlled cranes that will lift and remove the device, which is some 14 meters long.

The work poses a challenge as spent fuel may suffer damage if the device falls back into the pool during removal.

Workers accidentally dropped a 400-kilogram device into the pool last August. Though none of the rods suffered damage, removal was postponed for 4 months.

TEPCO has been preparing for the removal by developing equipment tailored to grip the device. Cushions have also been placed on top of the fuel rods.

TEPCO officials say all other work to decommission the plant will be suspended while the removal takes place as a hydrogen explosion in 2011 left the pool without a roof.
Source : NHK
http://www3.nhk.or.jp/nhkworld/english/news/20150730_05.html

July 30, 2015 Posted by | Japan | , , | Leave a comment

Strontium-90 detected in potentially discharged water from Reactor 1 and 3

Strontium-90-detected-in-potentially-discharged-water-from-Reactor-1-and-3-800x500_cOctober 20, 2014
2,800 ~ 11,000 Bq/m3 of Strontium-90 have been detected from pumped water around Reactor 1 and 3, according to Tepco.
On 10/1/2014, Tepco released nuclide analysis data of groundwater. The tested groundwater was pumped up from the facilities called “sub-drain” located beside Reactor 1 ~ 4.
These “sub-drains” were originally to reduce groundwater volume to flow into the basement of each reactor building, however abandoned because of the high level of contamination after 311. Tepco is trying to restart using these sub-drains to pump up highly contaminated water and to discharge to the sea.
(cf, Tepco to pump up highly contaminated groundwater for potential discharge today / Drainage plan submitted to NRA.
The samples were taken this September and last September. From the sample near Reactor 1, 11,000 Bq/m3 of Strontium-90 was detected last September. From the sample near Reactor 3, 2,800 Bq/m3 of Strontium-90 was measured this September.
These readings were not checked by third party organizations, so the actual density can be higher than announced.
Either way, the data shows groundwater contamination is spreading from around the reactor buildings to the outside of the port. (cf, Strontium-90 detected outside of Fukushima port / Highest reading in front of Reactor 4 too.

Click to access around_rb_141001-j.pdf

Source: Fukushimary Diary
http://fukushima-diary.com/2014/10/strontium-90-detected-potentially-discharged-water-reactor-1-3/

October 20, 2014 Posted by | Japan | , , , , | Leave a comment