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TEPCO Opens Up Space in Common Pool at Fukushima Daiichi to Receive Spent Fuel from Unit 3

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“X-6 penetration” at Unit 5
4 June, 2018
On May 31, the Tokyo Electric Power Co. (TEPCO) released a progress report on the decommissioning at the Fukushima Daiichi Nuclear Power Plants.
Four days earlier, on May 27, the power company began transferring some of the spent fuel currently stored in a common pool to a temporary facility at the site, for storage in dry casks, to create enough space in the pool to store spent fuel taken from the Unit 3 spent fuel pool when that is eventually removed.
At the temporary storage facility, TEPCO will pack the spent fuel in dry casks providing shielding and heat removal (with natural air circulation outside the casks) and store it under stable conditions.
By August, 483 spent fuel assemblies from the common pool will have been transferred to the facility using seven transport and storage casks, in anticipation of the arrival of 566 fuel assemblies (including unused 52 assemblies) from Unit 3.
On May 11, a problem was found at Unit 3—where a fuel handling machine has been in trial operation since March—inside a control panel for a crane used for moving fuel transportation containers to the ground. TEPCO nevertheless aims to begin removing fuel from the spent fuel pool around mid-FY18, as initially planned.
TEPCO will determine a method for removing fuel debris from the first unit by FY19 (April 2019 to March 2020), and the status of that effort was also included in the status report on May 31. The approach is to proceed after heightened understanding is made of internal conditions, the nature of the debris, and the effects when removed.
As that has not yet been fully completed, though, the effort will proceed gradually and incrementally, as follows: first investigating the interiors of the primary containment vessels (PCVs) through sampling, then carrying out small-scale removal of debris, followed by large-scale removal.
As for small-scale fuel removal, one promising method seems to be using a “X-6 penetration” rail to access the interiors of the PCVs (found in all the units) from the side, in order to exchange the control rod drive mechanism (CRDM). That method is already being used for inserting investigation devices into PCVs.
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June 7, 2018 Posted by | Fukushima 2018 | , , | Leave a comment

Coastal nuclear reactor resumes operations, joins 2 units nearby

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The No. 1 to No. 4 reactors (from top to bottom) at the Oi Nuclear Power Plant are seen from a Mainichi Shimbun helicopter, in Oi, Fukui Prefecture, on March 14, 2018.
March 14, 2018
FUKUI, Japan (Kyodo) — Kansai Electric Power Co. restarted Wednesday a reactor at its Oi plant on the Sea of Japan coast, located close to two other units already online, amid lingering safety concerns following the Fukushima disaster.
 
It is the first time that multiple nuclear reactors within the same vicinity have been in operation since the crisis at the Fukushima Daiichi plant, triggered by the March 2011 earthquake and tsunami.
 
The No. 3 reactor at the Oi plant is a mere 14 kilometers from the No. 3 and 4 units at the Takahama plant, all in the central Japan prefecture of Fukui.
 
Local residents are worried about the lack of an effective evacuation plan in the event accidents hit both the Takahama and Oi complexes at the same time.
 
The No. 3 Oi unit is the sixth reactor to resume operations in Japan after clearing stricter safety regulations implemented in the wake of the Fukushima disaster.
 
The government of Prime Minister Shinzo Abe, seeing nuclear power as an “important base-load power source,” is promoting the restart of nuclear reactors considered safe by regulators.
 
Under the current national energy policy, the government plans to generate between 20 and 22 percent of total electricity using nuclear power in fiscal 2030.
 
Kansai Electric aims to start commercial operations of the No. 3 Oi reactor in early April. The No. 4 reactor at the Oi plant is also expected to restart in May, having cleared the Nuclear Regulation Authority’s safety review along with the No. 3 unit in May 2017.
 

March 16, 2018 Posted by | Uncategorized | , , | Leave a comment

Roof completed for removal of spent fuel rods at Fukushima plant

February 21, 2018
Work was completed Feb. 21 on a half-cylinder roof designed to trap radioactive substances emitted when spent fuel rods are removed from the No. 3 reactor building at the Fukushima No. 1 nuclear plant.
Tokyo Electric Power Co., the plant’s operator, plans to remove the spent fuel from the building’s storage pool as early as this autumn.
Construction work on the roof–23 meters wide and 57 meters long–started in July 2017.
The final piece, weighing about 55 tons, was lifted by a crane and put into place on Feb. 21. The roof is located directly above the storage pool.
A hydrogen explosion severely damaged the original roof of the No. 3 reactor building days after the March 2011 Great East Japan Earthquake and tsunami triggered the meltdowns at the plant.
The 566 fuel assemblies in the storage pool pose a serious risk in the event of another disaster striking the plant.
Completion of the roof should advance TEPCO’s plans to remove the fuel rods as soon as possible.
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The final part of a roof is put in place on the top of the No. 3 reactor building at the Fukushima No. 1 nuclear power plant on Feb. 21.
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A photo taken from an Asahi Shimbun helicopter on Feb. 21 shows the completion of work for a roof at the No. 3 reactor building of the Fukushima No. 1 nuclear power plant on Feb. 21.
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The half-cylinder roof is designed to prevent radioactive substances from escaping during fuel-rod removal work in the No. 3 reactor building at the Fukushima No. 1 nuclear plant.

 

February 25, 2018 Posted by | Fukushima 2018 | , , | Leave a comment

Fukushima plant reactor #3 gets new roof cover

 

 
Workers at the crippled Fukushima Daiichi nuclear power plant have finished installing a new roof covering for the No.3 reactor building.
The work started last August to set up a dome-shaped cover. It is part of preparations for removing nuclear fuel from the reactor’s storage pool. A total of 566 spent and unused fuel units remain in the storage pool of the No. 3 reactor.
On Wednesday, workers installed the last part of the cover, which is 17 meters high and 22 meters wide, and weighs 55 tons.
The cover will prevent radioactive materials from spreading, and shield the building from winds.
Reactors at the Fukushima plant suffered meltdowns after a quake-triggered tsunami hit the plant on March 11th, 2011. The fuel units left in storage pools need to be removed as part of decommission work at the plant.
The plant’s operator, Tokyo Electric Power Company, will clear the pool of rubble and provide workers with training on remotely handling devices for the fuel removal.
Then, it plans to start removing nuclear fuel units from the No.3 reactor’s storage pool in autumn this year, ahead of those of other damaged reactors.

February 22, 2018 Posted by | Fukushima 2018 | , , | Leave a comment

Inside a meltdown-hit Fukushima reactor building

February 17, 2018
Seven years on, Tepco aims to pull fuel out of Unit 3’s rubble-strewn pool
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A crane and dome-shaped roof have been erected on the top floor of Fukushima Daiichi’s No. 3 building, in preparation for removing rods and rubble from the spent fuel pool
 
FUKUSHIMA, Japan — As the Fukushima Daiichi nuclear disaster unfolded in March 2011, a hydrogen explosion ripped through the No. 3 reactor unit. Nearly seven years on, steel framing and other debris still litter the spent fuel pool, along with 566 fuel rods.
The painstaking process of removing the rods is expected to begin sometime in the fiscal year that starts in April. The fuel extraction will be a first for reactor Nos. 1-3 at the Tokyo Electric Power Co. Holdings facility, which was crippled by the earthquake and tsunami that hit northeastern Japan.
On Feb. 8, reporters from The Nikkei were allowed into the No. 3 building to get a sense of the work that awaits. 
A 20-minute bus ride from the town of Tomioka took us to Fukushima Daiichi. After donning masks and protective clothing, we walked toward Unit 3. An elevator slowly lifted us to the top floor of the building, about 36 meters up. There, a crane for moving the spent rods stood ready, wrapped in plastic sheeting. We peered down into the pool but could not see the fuel, which lies under 4 to 5 meters of water.
Large slabs of rubble that fell into the pool have been removed, but smaller pieces remain.
Other decontamination work is proceeding gradually. Radiation on the top floor was measured as high as 2,000 millisieverts per hour in the disaster’s immediate aftermath, but now it is less than 1 millisievert.
Still, caution is a must. Near the pool, our dosimeters displayed relatively high readings of up to 0.7 of a millisievert per hour. “The reading has climbed, so let’s leave for now,” a Tepco supervisor said. As we moved on, we frequently checked to ensure our exposure would not exceed 0.1 of a millisievert a day. 
 
Spent fuel has been removed from reactor No. 4, which was not operating when the tsunami hit the plant. But the job will be a challenge at the meltdown-stricken Unit 3. The rods and rubble will be extracted with heavy equipment operated remotely, from a separate administrative building. 
While it normally takes about two weeks to remove spent fuel, Tepco intends to proceed carefully over the course of two years.

February 18, 2018 Posted by | Fukushima 2018 | , , | Leave a comment

Drone to probe Fukushima N-plant interior

February 10, 2018
feb 10 2018 drone inspection of reactor 3.jpg
Tokyo Electric Power Company Holdings Inc. plans to use a small unmanned aerial vehicle to closely inspect conditions inside the No. 3 reactor building of the Fukushima No. 1 nuclear power plant as early as this month.
TEPCO will use the drone to examine the location of scattered debris and the level of radiation inside the reactor building, among other things.
It will be the first drone-based research conducted inside the plant’s Nos. 1, 2 and 3 reactor buildings, in which nuclear meltdowns occurred.
The drone, called Riser, was developed by a British company. It measures 83 centimeters by 93 centimeters and weighs about four kilograms.
Riser is equipped with cameras and a dosimeter that can measure up to 2.5 sieverts of radiation per hour.
Even in indoor spaces inaccessible to GPS signals, the drone is capable of determining its position and avoiding obstacles using lasers.
The same model was used for decommissioning work at the Sellafield nuclear facility in Britain.
TEPCO’s plan is for the drone to enter the No. 3 reactor building through a bay for large cargo on the first floor, then fly upward through a series of openings from the first to the fifth floor.
The drone will check areas including the building’s third floor, which has not been sufficiently monitored because radiation levels are too high.
According to TEPCO, key equipment such as that used to cool spent nuclear fuel pools are located on the third floor.
Confirming the location of possible obstacles and the level of radiation is necessary before decommissioning work can progress.
Riser also has a mapping function that enables it to produce three-dimensional graphic images of its surroundings using lasers.
Combining these images with measurements of radiation levels allows for the production of maps outlining contamination levels inside the reactor buildings. TEPCO will consider making this kind of distribution map in the future.
A hydrogen explosion inside the No. 3 reactor building on March 14, 2011, destroyed the building’s upper structures.
Work is currently under way to construct a dome-shaped roof over the building to facilitate the removal of fuel that remains in the spent fuel storage pools.

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

Installation of a dome-shaped rooftop cover near completion at Unit 3 reactor

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Japan Fukushima Cleanup
In this Thursday, Jan. 25, 2018 photo, an installation of a dome-shaped rooftop cover housing key equipment is near completion at Unit 3 reactor of the Fukushima Dai-ichi nuclear power plant ahead of a fuel removal from its storage pool in Okuma, Fukushima Prefecture, northeast Japan, during an exclusive visit by The Associated Press. The hardest-hit reactor at the Fukushima plant in the March 2011 disaster is moving ahead of the other two melted reactors seven years later in what will be a decades-long cleanup. (AP Photo/Mari Yamaguchi)

 

January 31, 2018 Posted by | Fukushima 2018 | , , | Leave a comment

Worst-hit reactor at Fukushima may be easiest to clean up

By MARI YAMAGUCHI
jan 25 2018 reactor 3 dome.jpg
In this Thursday, Jan. 25, 2018, photo, an installation of a dome-shaped rooftop cover housing key equipment is near completion at Unit 3 reactor of the Fukushima Dai-ich nuclear power plant ahead of a fuel removal from… (AP Photo/Mari Yamaguchi)
OKUMA, Japan (AP) — High atop Fukushima’s most damaged nuclear reactor, the final pieces of a jelly-roll shaped cover are being put in place to seal in highly radioactive dust.
Blown apart by a hydrogen explosion in 2011 after an earthquake and tsunami hit Japan’s Fukushima Dai-ichi plant, reactor Unit 3 is undergoing painstaking construction ahead of a milestone that is the first step toward dismantling the plant.
 
The operating floor — from where new fuel rods used to be lowered into the core — has been rebuilt and if all goes as planned, huge cranes will begin removing 566 sets of still-radioactive fuel rods from a storage pool just below it later this year.
 
It has taken seven years just to get this far, but now the real work of cleaning up the Tokyo Electric Power Co. plant can begin.
“If you compare it with mountain climbing, we’ve only been preparing to climb. Now, we finally get to actually start climbing,” said Daisuke Hirose, an official at the plant’s decommissioning and decontamination unit.
Cleaning up the plant’s three reactors that had at least partial meltdowns after the earthquake and tsunami is a monumental task expected to take three to four decades. Taking out the stored fuel rods is only a preliminary step and just removing the ones in Unit 3 is expected to take a year.
Still ahead is the uncharted challenge of removing an estimated 800 tons of melted fuel and debris inside the cracked containment chambers — six times that of the 1979 Three Mile Island accident.
The area in and outside of Unit 3 is part construction site and part disaster zone still requiring protection from radiation. A makeshift elevator, then a wind-swept outdoor staircase, takes visitors to the operating floor, more than 30 meters (100 feet) above ground.
Daylight streams in through the unfinished section of the new cover, a tunnel-like structure sealed at both ends to contain radiation. An overhead crane that moves on rails stands at the side of the storage pool, the maker’s name, “Toshiba,” emblazoned in large red letters.
The explosion left major chunks of debris that have been removed from the storage pool, a painstaking operation done using remote-controlled machinery and with utmost care to avoid damaging the fuel rods. Smaller rubble lines the pool’s edge. The water’s surface is obscured by a blue netting to prevent more debris from accidentally tumbling in.
The severe damage to Unit 3 has, in the end, made it easier to clean up than the other two reactors.
Under the latest government roadmap approved last September, removal of the fuel rods from units 1 and 2 was delayed by three years until 2023, a second postponement from the original 2015, because further decontamination and additional safety measures are needed.
Unit 1 fell behind because of a delay in removing debris and repairing key components on the operating floor. The Unit 2 building remained intact, keeping high radiation and humidity inside, which makes it more difficult for workers to approach and decontaminate.
Radioactivity on the Unit 3 operating floor has fallen to a level that allows workers in hazmat suits and filter-masks to stay up to two hours at a time, though most work still needs to be done remotely.
The segments of the new cover were pre-assembled and are being installed one by one by remote-controlled cranes. With two pieces left, the plant operator says the cover will be completed in February.
Removing the fuel rods in Unit 3 will be done with a fuel-handling crane. It will move the rods out of their storage racks and pack them in a protective canister underwater. A second Toshiba crane, a 10-meter (33-foot) -high yellow structure across the operating floor, will lift the canister out of the pool and load it onto a vehicle for transport to another storage pool at the plant.
Crane operators and others assigned to the project, which requires caution and skill, have been rehearsing the procedures.
The 1,573 sets of fuel rods stored in spent fuel pools at the three reactors are considered among the highest risks in the event of another major earthquake. Loss of water from sloshing, structural damage or a power outage could cause meltdowns and massive radiation leaks because the pools are uncovered.
Hirose said that starting fuel removal at Unit 3 would be “a major turning point.”
Still, after the intact fuel rods are gone comes by far the most difficult part of decommissioning the plant: removing the melted fuel and debris from inside the reactors. Obtaining exact locations and other details of the melted fuel are crucial to determining the retrieval methods and developing the right kind of technology and robots. With most melted fuel believed to have fallen to the bottom, experts are proposing that it be accessed from the side of the containment vessel, not from the top as originally had been planned, based on the cleanup after an accident at the Three Mile Island nuclear plant in the United States.
Computer simulations and limited internal probes have shown that the melted fuel presumably poured out of the core, falling to the bottom of the primary containment vessels. Robotic probes at the Unit 3 and 2 reactors have captured images of large amounts of melted fuel, but attempts so far at Unit 1 have been unsuccessful.
Despite scarce data from inside the reactors, the roadmap says the methods for melted fuel removal are to be finalized in 2019, with actual retrieval at one of the three reactors in 2021. Hirose says it is premature to say whether Unit 3 will be the first.

January 31, 2018 Posted by | Fukushima 2018 | , , | 1 Comment

Fukushima dome roof takes shape, but radiation remains high

4 dec 2017 dome roof n3
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.
4 dec 2017 dome roof n3 2.jpg
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.

December 4, 2017 Posted by | Fukushima 2017 | , , , | Leave a comment

Image shows extent of damage to reactor at Fukushima plant

1 dec 2017 corroded tubes reactor 3.jpg
Severely damaged parts of a device once used to move control rods are stuck in a hole inside the pressure vessel of the No. 3 reactor at the Fukushima No. 1 nuclear plant. (Provided by International Research Institute for Nuclear Decommissioning)
An image taken by an underwater robot shows corroded tubes stuck in a hole created by melted fuel in the pressure vessel of the No. 3 reactor at the Fukushima No. 1 nuclear plant.
The image offers clues on the extent of the damage caused when fuel rods in the reactor melted through the bottom of the pressure vessel after the disaster at the nuclear plant unfolded in March 2011.
Tokyo Electric Power Co., operator of the plant, sent the specially designed robot into the reactor in July. The company earlier released images taken by the robot that showed ‘what is believed’ to be melted nuclear fuel debris.
In the image released on Nov. 30, TEPCO identified the severely corroded and damaged tubes as parts of a device used to move control rods. Normally, that device is located inside the pressure vessel.
TEPCO on Nov. 30 also said it would conduct another study inside of the containment vessel of the No. 2 reactor at the plant in January. The containment vessel surrounds the pressure vessel.
A telescopic stick more than 10 meters long and equipped with a camera will be used for the survey.

December 4, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

Once severely damaged Fukushima reactor building opened to media to showcase progress

Tepco’s representatives and METI’s officials have spent 15 minutes at the top floor of the reactor 3 building, 30 meters above the ground.
0,08mSv/per hour on the platform and 0,7mSv/per hour near the fuel pool with its 566 fuel assemblies supposed to be unloaded within 6 months. According to Tepco, workers cannot stay up there more than one hour or two per day….
The real content of that fuel pool is still mysterious, as no whole picture of that pool has ever been released.
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The top floor of the Fukushima No. 1 nuclear plant’s No. 3 reactor building is seen on Nov. 21, 2017. The spent fuel pool can be seen at lower left. (Mainichi)
The top level of the Fukushima No. 1 nuclear plant’s No. 3 reactor building was opened to the news media on Nov. 21.
The Ministry of Economy, Trade and Industry along with plant operator Tokyo Electric Power Co. (TEPCO) guided reporters to the reactor building’s top floor for a tour lasting about 15 minutes.
The building was badly damaged by a hydrogen explosion in the first days of the Fukushima nuclear crisis in March 2011. However, the debris has been cleared away, and radiation that had stood at 800 millisieverts per hour just after the reactor meltdowns was measured at 0.08 mSv/h on the 7-meter-high platform, on which fuel removal equipment and other devices have been installed, on Nov. 21. Closer to the fuel pool, the figure rose to 0.7 mSv/h. According to TEPCO, workers are limited to just one to two hours on the platform.
22 oct 2017 reactor 3.JPG
The top floor is about 30 meters from the ground. The spent fuel pool currently contains 566 fuel assemblies, and preparations are underway to start the removal process as early as mid-fiscal 2018, with equipment for the job already installed on the platform. A net currently covers the pool to prevent anything — or anyone — from falling in.
A semi-cylindrical cover is also being constructed to prevent radioactive materials from escaping when fuel removal operations begin.

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

Preparations to unload reactor 3’s pool

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On November 8th two machines arrived at Fukushima Daiichi : a bridge crane and a fuel handling machine. These two machines will be installed on the reactor 3’s platform in order to unload the pool of its fuel.

Source: Pierre Fetet http://www.fukushima-blog.com/

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

Muons suggest location of fuel in unit 3

Some of the fuel in the damaged unit 3 of the Fukushima Daiichi plant has melted and dropped into the primary containment vessel, initial results from using a muon detection system indicate. Part of the fuel, however, is believed to remain in the reactor pressure vessel.

FD3 muon measurements Oct 2 2017)Structures within the reactor building of unit 3 can be seen in images obtained using muon data (Image: Tepco)

 

Muons are high-energy subatomic particles that are created when cosmic rays enter Earth’s upper atmosphere. These particles naturally and harmlessly strike the Earth’s surface at a rate of some 10,000 muons per square meter per minute. Muon tracking devices detect and track these particles as they pass through objects. Subtle changes in the trajectory of the muons as they penetrate materials and change in direction correlate with material density. Nuclear materials such as uranium and plutonium are very dense and are therefore relatively easy to identify. The muon detection system uses the so-called permeation method to measure the muon data.

Tokyo Electric Power Company (Tepco) installed a muon detection system on the first floor of unit 3’s turbine building. Measurements were taken between May and September this year.

Tepco said analysis of muon examinations of the fuel debris shows that most of the fuel has melted and dropped from its original position within the core.

Prior to the 2011 accident, some 160 tonnes of fuel rods and about 15 tonnes of control rods were located within the reactor core of unit 3. The upper and lower parts of the reactor vessel contains about 35 tonnes and 80 tonnes of structures, respectively.

The muon examination indicates that most of the debris – some 160 tonnes – had fallen to the bottom of the reactor pressure vessel and resolidified, with only about 30 tonnes remaining in the reactor core. Tepco said another 90 tonnes of debris remains in the upper part of the vessel.

The bulk of the fuel and structures in the core area dropped to the bottom of the reactor pressure vessel (RPV), Tepco believes. While part of the molten fuel is understood to have then fallen into the primary containment vessel (PCV), “there is a possibility that some fuel debris remains in the bottom of the RPV, though this is uncertain”, the company noted.

Similar muon measurements have already been conducted at units 1 and 2 at Fukushima Daiichi. Measurements taken at unit 1 between February and September 2015 indicated most of the fuel was no longer in the reactor’s core area. Measurements taken between March and July 2016 at unit 2 showed high-density materials, considered to be fuel debris, in the lower area of the RPV. Tepco said that more fuel debris may have fallen into the PCV in unit 3 than in unit 2.

FD1-3 fuel debris - September 2017 - 460 (Tepco)The current understanding of fuel location in units 1-3 (Image: Tepco)

 

Tepco said the results obtained from the muon measurements together with knowledge obtained from internal investigations of the primary containment vessels using remote-controlled robots will help it plan the future removal of fuel debris from the damaged units.

http://www.world-nuclear-news.org/RS-Muons-suggest-location-of-fuel-in-unit-3-0210174.html

October 5, 2017 Posted by | Fukushima 2017 | , , | 1 Comment

Construction of the Cover for Fukushima Daiichi Reactor 3 Continues

reactor 3 dome aug 9 2017.jpg

September 10, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

Installation of Unit 3 fuel removal cover dome roof at Fukushima Daiichi

Tokyo Electric Power Co. shows its installation work to cover the upper part of the No. 3 nuclear reactor building that was blown off by the March 2011 hydrogen explosion at the Fukushima No. 1 nuclear power plant.

 

OKUMA, Fukushima Prefecture–Tokyo Electric Power Co. showed reporters its progress in installing a new roof above Fukushima No. 1 nuclear plant’s No. 3 reactor building on Aug. 2, ahead of work to remove spent nuclear fuel from a storage pool.

The company demonstrated how it is carrying out the work, which is necessary because the upper section of the reactor building was blown off in a hydrogen explosion in the nuclear disaster at the plant in March 2011.

The roof project marks a step toward removing nuclear fuel assemblies in the spent nuclear fuel storage pool in the building.

august 2 2017 new roof reactor 3.jpgA photograph taken from an Asahi Shimbun helicopter shows a section of the half-tubular shaped roof being installed over the No. 3 reactor building at the Fukushima No. 1 nuclear power plant on Aug. 2.

 

To prevent the spread of radioactive material, TEPCO started to set up the half-tubular shaped cover to shield the damaged reactor building at the end of last month.

new roof for reactor 3 august 2 2017 2.jpgA section of the roof is lifted by a crane to place it on top of the No. 3 nuclear reactor building at the Fukushima No. 1 nuclear power plant on Aug. 2.

 

new roof for reactor 3 august 2 2017 3An artist’s rendition of the completed roof that will shield the upper part of the No. 3 nuclear reactor building that was blown off in the March 2011 hydrogen explosion at the Fukushima No. 1 nuclear power plant.

 

The 566 nuclear fuel assemblies currently lying in the pool will become a significant risk if another major disaster strikes the area.

TEPCO is expected to start removing the fuel from around mid-fiscal 2018.

Early on Aug. 2, part of the roof measuring around 17 meters high and weighing 37 tons was lifted to the top floor of the reactor building with a large crane.

Workers connected the new part of the cover to another section that had been installed at the end of July, completing one eighth of the roof. When finished, it will be about 60 meters long.

Dedicated removal machines are needed to retrieve the fuel from the storage pool. The machines that had been used at the plant prior to the accident were removed because they were severely damaged by the hydrogen explosion.

http://www.asahi.com/ajw/articles/AJ201708020046.html

Source : Tepco

2017.7.31 Installation of Unit 3 fuel removal cover dome roof at Fukushima Daiichi Nuclear Power Station

http://www.tepco.co.jp/en/news/library/archive-e.html?video_uuid=z2v3h93c&catid=61785

Installation of Unit 3 spent fuel removal cover dome roof at Fukushima Daiichi Nuclear Power Station (On-site demonstration) Photos taken on: Aug 2, 2017

http://www.tepco.co.jp/en/news/library/archive-e.html?video_uuid=w8a3j0h4&catid=69631

August 3, 2017 Posted by | Fukushima 2017 | , , | Leave a comment