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Submersible robot ‘little sunfish’ to inspect the damaged primary containment vessel (PCV) of Fukushima Daiichi Unit 3

Swimming robot ‘little sunfish’ to inspect crippled Fukushima plant

 

Japan has unveiled a small swimming robot that will inspect the damage at the crippled Fukushima nuclear power plant. The device weights 2kg, is 13cm in diameter and will be able to swim deep into the melted reactor, its developers say.

The Japan-based International Research Institute for Nuclear Decommissioning (IRID) unveiled the robot, dubbed ‘mini manbo’ (little sunfish) in the media, together with Toshiba group on Thursday.

The robot “is small enough and resilient enough to enter and inspect the damaged primary containment vessel [PCV] of Fukushima Daiichi Nuclear Power Station Unit 3,” a statement from the IRID said, adding that the device will be deployed this summer.  

swimming robot 15 june 2017.jpg

 

The device is equipped with two cameras and can be remotely controlled via a wire, while operators can record its progress through the coolant. ‘Little sunfish’ will deliver a video feed that “will clarify damage to the PCV interior and information on how best to retrieve fuel debris,” the IRID added.

The major advantage of the robot is that it “can avoid various obstacles,” Tsutomu Takeuchi, a senior manager at the nuclear energy division of Toshiba, told AP. The company is tasked with helping to clean up the damaged plant.

The device was created for inspection of the primary containment vessel (PCV) of Unit 3 of the crippled plant. Unit 3 was flooded with coolant to a depth of about 6 meters (20ft) and in order to make a proper clean-up, such a coolant must be located and mapped, according to the IRID.

The penetration hole giving access to the PCV is only 14cm in diameter, limiting the size of any robot that can be deployed,” the IRID added.

Thus, the newly-presented robot seems ideal for the job. 

The robot’s radiation resistance is approximately 200 Sievert (Sv), according to its characteristics. For comparison, an exposure of about 1 sievert can cause biological damage to living tissue, according to the International Atomic Energy Agency (IAEA).  

Scientists developed ‘mini manbo’ with the aim of operating in a highly radioactive environment,” Goro Yanase, general manager of Toshiba’s Nuclear Energy Systems & Services Division, said.

We succeeded in developing a small robot with high-level radiation resistance, and through its deployment we expect to get information that will support the advance of decommissioning,” he added.

The Fukushima Daiichi nuclear power plant suffered a blackout and subsequent failure of its cooling systems in March 2011, when it was struck by an earthquake and tsunami. Three of the plant’s six reactors were hit by meltdowns, making the disaster the worst since the Chernobyl catastrophe in the USSR in 1986.

Japanese authorities have repeatedly sent robots to inspect the contained area of the crippled plant but the devices either broke down or the missions were aborted. In February, such an attempt ended in failure as a clean-up robot stopped working two hours after it was sent to the inactive Reactor 2 at the nuclear complex.

Following the failure, Naohiro Masuda, president of Fukushima Daiichi Decommissioning, said that more creativity was needed to produce robots that can find and assess the condition of melted fuel rods at the high-level radiation site. 

https://www.rt.com/news/392441-japan-underwater-robot-fukushima/

 

Toshiba unveils submersible video robot to probe reactor 3 at Fukushima No. 1 plant

 

YOKOSUKA, KANAGAWA PREF. – Toshiba Corp. unveiled on Thursday a submersible robot to take live video of reactor 3 at the Fukushima No. 1 power plant to confirm whether fuel debris is sitting at the bottom of a pool of radioactive water inside.

The location and condition of the fuel in the three reactors hit by core meltdowns is critical information for Tokyo Electric Power Company Holdings Inc., which runs the plant. Removing the fuel debris is considered the most difficult part of decommissioning the complex.

Unit 3 has the highest level of water inside at 6 meters. The fuel debris inside is presumed to have melted through its pressure vessel and settled at the bottom of its primary containment vessel.

Until today, no one has seen the situation inside reactor 3,” said Tsutomu Takeuchi, senior manager at Toshiba’s Fukushima Restoration and Fuel Cycle Project Engineering Department.

If we can observe the situation inside the reactor, that would be a huge leap in our ongoing effort to extract the debris” and eventually shut down the wrecked plant, he said during a demonstration of the robot at the Port and Airport Research Institute in Yokosuka, Kanagawa Prefecture.

Co-developed with the International Research Institute for Nuclear Decommissioning, the cylindrical 30-cm robot, dubbed the “mini manbo” (miniature sunfish), has a camera that can move 180 degrees vertically on its front and a fixed camera on its rear, allowing it to crawl through the water while capturing images.

Tepco plans to send the remotely controlled robot into the reactor as early as mid-July. A camera inserted into the reactor in October 2015 was unable to reach the bottom of the containment vessel.

No probe has been able to confirm the location or condition of the nuclear debris in any of the three crippled reactors.

Tepco sent a scorpion-shaped robot developed by Toshiba and the institute into reactor 2 in February, but it broke down before reaching its target under the pressure vessel after a tire got stuck.

In March, Tepco’s five-day robot-based investigation failed to capture an image of what was thought to be fuel debris in reactor 1.

A separate Tepco probe in January found black lumps in reactor 2’s pressure vessel but couldn’t immediately confirm they were fuel.

In December, the government estimated that the total cost of the Fukushima disaster would reach ¥21.5 trillion, including ¥8 trillion for decommissioning. That was almost doubled the initial estimate of ¥11 trillion.

Takeuchi of Toshiba did not reveal how much it cost to develop mini manbo.

http://www.japantimes.co.jp/news/2017/06/15/national/toshiba-unveils-submersible-video-robot-probe-reactor-3-fukushima-no-1-plant/#.WUK8RTdpzrc

n-robot-a-20170616.jpgTsutomu Takeuchi, senior manager at Toshiba’s Fukushima Restoration and Fuel Cycle Project Engineering Department, shows off a robot it claims can probe water-filled reactor 3 at the defunct Fukushima No. 1 nuclear plant.

 

Swimming and wriggling robots unveiled for Fukushima clean-up

University and industry scientists have demonstrated new robots specialised for moving through and searching scenes of destruction that are impossible or dangerous for humans to enter.

Hardy, agile, remote-controlled robots will be vital for the decommissioning of power plants, particularly in the case of the Fukushima Daiichi Nuclear Power Plant, which suffered a meltdown in 2011 following a devastating tsunami and earthquake.

Robots can spend hours or days in environments so highly radioactive that a human worker would be killed in seconds.

The Japanese government hopes to start the challenging task of removing hundreds of tonnes of melted fuel after the Tokyo 2020 Olympics, potentially beginning work in 2021. For this to be possible, engineers need to know the exact location of the fuel, and understand the extent of the structural damage to the reactors.

Among other efforts, a snake-like robot was used in 2011 to explore the reactors, but was trapped repeatedly by obstacles and its camera was blocked. A “scorpion” inspired crawling robot also failed to navigate the site and was abandoned inside.

Years later, a new version of the snake-like robot has been revealed by Japanese scientists, including a team from Tohoku University in Sendai: a region severely affected by the tsunami and earthquake.

The robot stretches to eight metres in length, has a camera attached to the front and can move at speeds of up to 10cm per second.

It wriggles in a serpentine motion, propelled by the vibrations of the brush-like hairs that cover its body. Unlike any other robot, it can also “rear” its tip like the head of a snake, shooting a small jet of air to lift it. This allows it to climb over obstacles – such as debris in a disaster zone – up to 20cm in height.

According to Professor Satoshi Tadokoro of Tohoku University, the robot could search for people trapped in collapsed homes following earthquakes, and test the structural safety of damaged buildings. The researchers hope to have it ready to assist in search and rescue operations and other tasks within three years of durability testing.

swimming-robot
Meanwhile, an alternative disaster relief robot has been unveiled by Toshiba and the public International Research Institute for Nuclear Decommissioning. This swimming robot is the size of a loaf of bread is and fitted with lights, camera and tail propellers.

It is designed specifically to inspect meltdown damage at the Fukushima nuclear plant, and will enter the primary containment vessel of Fukushima’s Unit 3 this summer to locate melted fuel in radioactive water.

https://eandt.theiet.org/content/articles/2017/06/swimming-and-wriggling-robots-unveiled-for-fukushima-clean-up/

 

June 16, 2017 Posted by | Fukushima 2017 | , , | 1 Comment

Submersible Crawling Robot to Examine Interior of Fukushima Daiichi-3 PCV before Fuel Debris Is Removed

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On May 25, the Tokyo Electric Power Co. (TEPCO) released a status report on the ongoing decommissioning work at the Fukushima Daiichi Nuclear Power Plants, which suffered a tsunami-caused meltdown in March 2011.

Starting two months ago, in March, a self-propelled robot has been used to investigate the interior of the primary containment vessel (PCV) of Unit 1 at Fukushima Daiichi—a necessary step before fuel debris can be removed. As of April 6, the robot had sampled deposits twice.

Fluorescent X-ray spectroscopy has now confirmed the presence of elements that had originally existed in the PCV, such as iron and nickel within the reactor core internals, stainless steel in the heat-insulating materials, zinc in the paint, and lead in the shielding materials.

Although uranium was confirmed as the primary radioactive nuclide within Unit 1, it is not necessarily part of the fuel debris there, given that that element exists naturally. TEPCO said that it would carry out more detailed analyses to confirm the uranium’s source.

As the water level in the PCV of Unit 3 is higher than that in Units 1 and 2, its so-called “X-6 penetration”—which would give easier access to the inside of the pedestal (under the reactor pressure vessel)—is submerged. TEPCO plans to investigate the interior of that unit’s PCV at an undetermined date this summer using a submersible robot that can both crawl and swim. Earlier this month, the power utility began taking measurements using muon observation technology to determine the location of fuel debris.

Under the “Mid-and-Long-Term Roadmap” toward decommissioning, TEPCO will determine policies on fuel debris removal at each Fukushima Daiichi unit this summer. According to its May 22 report to an expert panel of the Nuclear Regulation Authority (NRA), the power company has already made investigations to determine general conditions inside the individual PCVs.

TEPCO will continue to focus on gathering information during the current fiscal year (ended March 31, 2018), including that on the forms and distribution of fuel debris—necessary to determine the means to remove it—and safety measures for the actual removal work.

http://www.jaif.or.jp/en/submersible-crawling-robot-to-examine-interior-of-fukushima-daiichi-3-pcv-before-fuel-debris-is-removed/

 

June 5, 2017 Posted by | Fukushima 2017 | , , , | Leave a comment

TEPCO fails to pinpoint melted fuel at Fukushima No. 1 nuclear plant

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A photo capturing contaminated water at the Fukushima No. 1 nuclear plant, which was taken by a robot on March 21, 2017.

Tokyo Electric Power Co. (TEPCO) failed to locate melted nuclear fuel inside the No. 1 reactor at the disaster-stricken Fukushima No. 1 Nuclear Power Plant in a robot probe, though it found higher levels of radiation toward the bottom of the reactor container vessel, the utility said on March 27.

TEPCO made the announcement after analyzing data obtained from a probe conducted from March 18 through 22, in which a remotely controlled robot was sent into the No. 1 reactor’s container vessel for research.

The power company is set to finalize a decision to take out melted fuel from the No. 1 through No. 3 reactors as early as this coming summer, accelerating work to decommission the facilities. Like a similar robot probe inside the No. 2 reactor last month, however, the latest survey on the No. 1 reactor also failed to obtain data necessary to extract melted fuel, such as where the fuel is located. Therefore, the utility is compelled to consider fetching melted fuel in the absence of sufficient data.

TEPCO injected a robot that can move on a running belt into the container vessel of the No. 1 reactor. The robot hung a wire holding a camera and a dosimeter at its tip from a metal grating for workers and measured the condition of the contaminated water below. From March 18 to 22, the robot examined an area near a slot from which the device is injected into the vessel and measured 1.5 to 11 sieverts per hour of radiation. Between March 20 and 22, the robot explored an area around the openings for workers at the bottom of the container vessel, which is close where melted fuel is believed to be situated, and detected measurements of 3 to 9.4 sieverts of radiation.

Sand-like sediment was found to be spreading across the bottom of the container vessel. Because of accumulated sediment near the openings, the robot could gauge radiation doses only up to a height of 90 centimeters from the bottom of the vessel. Compared to the radiation levels at the same height of an area where melted fuel is believed not to exist, the area near the openings showed higher radiation readings.

It is believed that most of the melted fuel at the No. 1 reactor has spread across the contaminated water accumulating at the bottom of its container vessel. TEPCO believes that melted fuel is likely leaking from those openings.

Naohiro Masuda, head of TEPCO’s Fukushima Daiichi Decontamination & Decommissioning Engineering Co., told a press conference on March 7, “The results of this probe will be precious resources for us to make a decision on our plan.”

http://mainichi.jp/english/articles/20170328/p2a/00m/0na/014000c

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March 29, 2017 Posted by | Fukushima 2017 | , , | 1 Comment

New video from Fukushima Daiichi

 

New video from inside a crippled Fukushima Daiichi nuclear reactor shows possible melted fuel.

http://www.ntv.co.jp/englishnews/society/new_video_from_fukushima_daiichi/

March 29, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

The Robot Probe Cannot Confirm Where is the Melted Fuel of Unit 1

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Tokyo Electric Power Company announced on February 23 that it had completed a robot probe survey lasting five days in the reactor containment vessel of Fukushima Daiichi nuclear power plant Unit 1.

Its goal was to confirm the whereabout of the melted nuclear fuel, but it was blocked by piping and could not put the camera in athe place where nuclear fuel could be seen.

Information necessary for taking out the nuclear fuel to decommission the reactor remains inadequate, and some voices began to question the robot conducted investigation method.

During the 5-day survey, there was also a point where the measuring instrument with an camera and a radiation dosimeter integrated together was hung up in a range from 0 to 3 meters from the bottom of the containment vessel, pipes and debris blocking its path in many points. The radiation dose in the water is from 3.0 to 11 Sv. Per hour. It was not possible to directly check the melted nuclear fuel.

TEPCO and the country are facing the decommissioning of a furnace …

http://www.asahi.com/articles/photo/AS20170323005483.html

March 24, 2017 Posted by | Fukushima 2017 | , , , , | Leave a comment

Tepco robot failed to capture images of melted fuel in reactor 1

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A photo taken by a robot on Wednesday shows an underwater image of water pool on the bottom of the containment vessel of the reactor 1 at the Fukushima No. 1 plant

Tokyo Electric said Thursday that it failed to get any photos of potential fuel debris during a five-day probe of the primary containment vessel at reactor 1 of the Fukushima No. 1 power plant.

Tokyo Electric Power Company Holdings Inc., however, stressed that the investigation was worthwhile because its robot was able to take underwater images in the pool of water at its bottom and gauge its radiation level, which will help it estimate where the melted fuel lies.

The monstrous tsunami of March 11, 2011, tipped reactors 1, 2 and 3 into core meltdowns. The molten fuel rods then penetrated their pressure vessels before apparently dropping to the bottom of the giant containment vessels.

There is about a 2.5-meter deep water pool at the bottom of the primary containment vessel of reactor 1, and Tepco believes most of its melted fuel rods fell into it. Thus the main mission of the robot investigation this time was to capture underwater images.

The robot traversed gratings set up several meters above the vessel’s bottom and lowered a wire with a camera and dosimeter on its tip at 10 locations in the water.

Yet none of the images disclosed by Tepco showed anything resembling fuel debris, while parts of machinery, such as a valve, were captured.

When the robot dangled the camera on spots where Tepco thought there was a higher probability of locating the fuel, it instead found a 90-cm pile of sediment.

Tepco spokesman Yuichi Okamura said the sediment is probably not fuel debris, given the relatively low radiation readings, which ranged from 5.9 to 9.4 sieverts per hour.

Although the readings indicate extreme danger to people, Okamura said the readings would have been much higher had they been melted fuel rods. He said Tepco had no idea what the sediment is but added that there was a possibility it was covering the fuel.

According to Okamura, radiation readings get weaker by a hundredth if blocked by a meter of water. Since the robot detected readings from 5.9 to 9.4 sieverts per hour about 90 cm above the pool’s bottom, there might be something down there emitting strong radiation.

Tepco plans another investigation this month to pick up samples of the sediment.

While no fuel debris was recognized, Okamura said Tepco would review the data and analyze it further. By comparing radiation readings from various locations, the utility might be able to roughly pinpoint where the melted rods lay, he said.

He added that it was an achievement that the robot lasted for five days in the deadly radiation and that Tepco was able to retrieve it.

http://www.japantimes.co.jp/news/2017/03/24/national/tepco-robot-failed-capture-images-melted-fuel-reactor-1/#.WNQ_hBh7Sis

March 24, 2017 Posted by | Fukushima 2017 | , , , | Leave a comment

Survey under way of Fukushima Daiichi 1 vessel

Fukushima Daiichi 1 PCV robot survey - 20.03.2017

The PMORPH robot within unit 1’s PCV

A robot has entered into the primary containment vessel of the damaged unit 1 of the Fukushima Daiichi plant and provided Tokyo Electric Power Company (Tepco) with radiation and temperature measurements within it. The company hopes the data, together with video footage, will enable it to locate the molten fuel in the unit.

On 18 March, Tepco inserted the PMORPH robot into unit 1 in the first of a series of four planned robot explorations of the basement area of its primary containment vessel (PCV) around the pedestal, on which the reactor pressure vessel sits. The investigation is part of preparatory work for the eventual removal of fuel debris.

The PMORPH robot was developed by Hitachi-GE Nuclear Energy and the International Research Institute for Nuclear Decommissioning (IRID). It can assume a long, straight shape for passing through narrow spaces, such as pipes. Alternatively, it can rotate its crawlers by 90 degrees in relation to its central body to assume a U-shape, with the crawlers providing better stability when travelling over flat surfaces.

The robot features a combined total of five cameras and also includes a winch used for lowering and raising a sensor unit that incorporates an underwater radiation-resistant camera, LED and a dosimeter.

In the latest investigation, the robot travelled along a section of the first floor grating, on which it measured a radiation dose of 7.8 Sieverts per hour. The robot also lowered its sensor unit into the water that has collected at the bottom of the primary containment vessel. At a height of about 1 metre above the PCV basement floor, Tepco recorded a dose level of 1.5 Sv/h. The robot also recorded temperature measurements within the PCV of 14-23°C.

Last month a “scorpion-shaped” robot developed by Toshiba and IRID was sent into the primary containment vessel of unit 2 of the Fukushima Daiichi plant. “In that case,” Tepco said, “although the robot was obstructed from reaching all the way into the pedestal area, important information was obtained about the conditions at the base of the reactor.” Readings indicate the temperature within the area of the containment vessel where the robot stopped was around 16.5°C and the dose rate was about 210 Sv/h, significantly higher than those measured in unit 1.

Tepco said the latest reading and images obtained from unit 1 will now be examined in greater detail. “The conditions of the PCV basement floor will be examined later,” it noted.

The insertion of the PMORPH robot follows an investigation of the unit’s containment vessel by another shape-changing robot in April 2015. That was the first time a robot had entered the containment vessel of any of the damaged units. However, after taking several images and measurements, that robot got stuck in the grating and stopped working.

Tepco is preparing to conduct similar investigations using a robot in unit 3 at the plant.

http://www.world-nuclear-news.org/RS-Survey-under-way-of-unit-1-vessel-2003174.html

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

Progress of Unit 1 PCV Internal Investigations – March 18. 2017

Preliminary report of March 12 investigation 1/2

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Preliminary report of March 12 investigation 2/2

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Impact to the surrounding environment :

The radiation level of 7.8 Sv/h was measured by a dosimeter during the March 18 investigation, but the radiation impact has been reduced by the shielding of PCV concrete walls and steel. No radiation impact has been observed in the surrounding environment.

The investigation is conduced while creating a boundary around the guiding pipe to prevent the air inside the PCV from leaking to the outside.

No significant changes have been observed at the monitoring posts and dust monitors after the investigation, compared to the before.

Real-time data of the monitoring posts and dust monitors along the site boundary are available on the website.

Reference URL:

http://www.tepco.co.jp/en/nu/fukushima-np/f1/index-e.html

http://www.tepco.co.jp/en/nu/fukushima-np/f1/dustmonitor/index-e.html

Monitoring of the plant parameters:

Although the radiation level of 7.8 Sv/h was measured by a dosimeter during the March 18 investigation,it does not mean that a new phenominonhas occurred but rather the area that has not been investigated since the March 2011 accident was investigated for the first time.

Plant parameters are monitored all the time during the investigation, and no significant changes have been observed in the PCV internal temperatures after the investigation, compared to the before.

The condition of cold shutdown has not been changed. Temperature data inside the PCV are available on the website.

Reference URL: http://www.tepco.co.jp/en/nu/fukushima-np/f1/pla/index-e.html

March 22, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

Robot probe of No.1 reactor to continue until Wed.

 

The operator of the crippled Fukushima Daiichi nuclear power plant says a robotic survey of fuel debris at the No. 1 reactor is being hampered by plumbing and other structures. The utility says it will extend the probe by one day, until Wednesday.

So far engineers have detected strong radiation of about 11 sieverts per hour in the water inside the containment vessel.

Tokyo Electric Power Company on Saturday started sending a remote-controlled robot into the reactor’s containment vessel to look at the state of debris — a mixture of melted fuel and reactor parts. The robot is equipped with a camera and a dosimeter.

The melted fuel is believed to still be at the bottom of the vessel, where about 2 meters of contaminated water accumulates.

TEPCO released the results of the ongoing survey on Tuesday. It said the robot moved to a location believed to be just above the debris and lowered the camera and dosimeter into the accumulated water.

The dosimeter detected radiation of 6 sieverts per hour one meter from the bottom. But piping prevented the device from reaching deeper, and it has yet to confirm the debris.

TEPCO also said the robot recorded about 11 sieverts of radiation per hour about 30 centimeters from the vessel’s bottom at another location. Officials believe the radiation may be coming from contaminated fragments that fell to the bottom, as they expected no debris there.

Through the extended probe, TEPCO hopes to collect more data on conditions inside the vessel.

https://www3.nhk.or.jp/nhkworld/en/news/20170321_33/

 

March 22, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

Clearer water inside reactor 1 should help find melted fuel at Fukushima plant

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A robot on March 18 took this image of a valve and a pipe in cooling water at the bottom of the containment vessel of the No. 1 reactor at the Fukushima No. 1 nuclear power plant.

Cooling water in the No. 1 reactor of the Fukushima No. 1 nuclear plant has improved in transparency, which should make it easier to pinpoint the location of melted nuclear fuel, the plant’s operator said.

The improved transparency, compared with the level two years ago, was confirmed on March 18, when a research robot took an image that clearly showed a valve and a pipe in the water at the bottom of the reactor’s containment vessel, Tokyo Electric Power Co. said March 19.

Devices on the robot measured radiation levels of 7.8 sieverts per hour on a metal stage for workers and 1.5 sieverts per hour in the water.

The research robot on March 20 and 21 will study areas where the melted nuclear fuel could exist.

http://www.asahi.com/ajw/articles/AJ201703200028.html

March 21, 2017 Posted by | Fukushima 2017 | , , , | Leave a comment

Robot Probe Forays Inside Fukushima Daiichi Reactor 1

robot probe reactor 1 march 19 2017 2

Grating inside the containment vessel of the No. 1 reactor at the crippled Fukushima No. 1 nuclear plant is seen in this handout image captured by a robot Saturday.

Robot makes foray into reactor 1

Tokyo Electric on Sunday confirmed lethally high radiation levels inside the primary containment vessel of reactor 1 at the heavily damaged Fukushima No. 1 nuclear plant but found they were not nearly as high as those recently logged in reactor 2.

Using a camera-equipped robot on Saturday, Tepco logged 7.8 sieverts per hour on some grating inside the vessel and 1.5 sieverts per hour in water pooled at its bottom.

Those figures are far lower than the 210 sieverts per hour measured at one spot in the PVC of the No. 2 reactor last month, but they are still extremely high.

The four-day probe launched by Tepco on Saturday is aimed at locating the melted fuel rods inside the No. 1 reactor building.

The primary mission of the robot is to investigate the bottom of the containment vessel to see if it can capture images of the melted fuel. Debris is believed to have penetrated the vessel and fallen into the surrounding containment vessel as a result of the heavy damage inflicted by the March 2011 tsunami that devastated eastern Tohoku.

The pressure vessel is the main component of the reactor and contains the fuel rod assemblies. Finding the exact location and condition of the melted fuel is considered critically important to dismantling the reactors.

However, the high radiation inside poses a daunting challenge for those involved in the decommissioning work.

In photos handed out to the media, a valve is shown covered in a yellowish substance that the utility said could be rust.

Another photo shows the grating that the robot, which is attached to a cable, was traveling on.

The utility had sent the robot into the PVC of reactor 1 two years ago but it could only capture images of the grating at the time.

Tepco said the robot can withstand up to 1,000 sieverts before malfunctioning. It traveled about 5 meters on Saturday and will eventually make its way to the other side of the concrete structure through a space that runs beneath the pressure vessel, which houses the core.

If the robot reaches its goal, computer simulations by Tepco show that there is a chance that melted fuel rods could be found there, Tepco said.

In January and February, Tepco investigated the containment vessel of the No. 2 reactor.

It is now preparing to conduct a similar robot probe of the reactor 3.

http://www.japantimes.co.jp/news/2017/03/19/national/robot-makes-foray-reactor-1/#.WND_z6KmnIV

robot probe reactor 1 march 19 2017

March 21, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

Robot probe of No.1 reactor started on Saturday

march 17, 2017 robot reactor 1

 

The operator of the damaged Fukushima Daiichi nuclear power plant started a robotic survey inside the No. 1 reactor on Saturday.

Tokyo Electric Power Company send a remote-controlled robot into the reactor’s containment vessel to look at the state of debris — a mixture of molten fuel and reactor parts. The debris is believed to be under contaminated water at the bottom of the vessel.

The utility had originally planned to start the probe on Tuesday. But it called off work when images from a camera to monitor the robot became unavailable.

The company later ascertained the cable connecting the camera to the monitor screen was broken.

TEPCO said it replaced the cable with a new one. It plans to conduct the survey for 4 days using the robot equipped with a camera and dosimeter.

https://www3.nhk.or.jp/nhkworld/en/news/20170317_30/

March 20, 2017 Posted by | Fukushima 2017 | , , | Leave a comment

TEPCO to use ‘fishing gear-like’ robot to hunt for melted fuel at Fukushima nuke plant

Tokyo Electric Power Co. (TEPCO) said it will send a fishing gear-like robot into the nuclear fuel containment vessel of the Fukushima No. 1 nuclear plant’s No. 1 reactor on March 14 to examine the state of melted nuclear fuel.
This will be the power company’s latest in a series of attempts to find and examine nuclear fuel at the plant using robots. TEPCO plans to spend four days on the search in hopes of ascertaining the state of the fuel for the first time. The melted fuel is believed to be in the bottom of the containment vessel, where radioactively contaminated water has accumulated.

The rod-shaped robot measuring about 70 centimeters long will travel through the water inside the vessel after being dropped in on a cable — like fishing — through a gap in scaffolding at the site.

http://mainichi.jp/english/articles/20170310/p2a/00m/0na/003000c

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

TEPCO to conduct robotic probe of No.1 reactor next week Tuesday

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TEPCO to conduct robotic probe of No.1 reactor

The operator of the Fukushima Daiichi nuclear power plant says it will send a remote-controlled probe into the crippled No.1 reactor next week.

Tokyo Electric Power Company said on Thursday a robot equipped with a camera and dosimeter will be inserted into the containment vessel of the reactor, beginning on Tuesday.

The 4-day probe is part of the utility’s effort to remove melted nuclear fuel from the 3 reactors at the plant that experienced meltdowns following the massive earthquake and tsunami on March 11th, 2011.

TEPCO believes the fuel penetrated the No. 1 reactor’s pressure vessel and has remained at the bottom of the containment vessel as fuel debris.

The robot is 70 centimeters long and about 10 centimeters wide. It will enter the containment vessel through a pipe.

The plan is to lower the camera and dosimeters attached to cables at 5 locations into contaminated water at the bottom, which is about 2 meters deep.

TEPCO officials say that even if the water is too murky to capture images, data from the dosimeter will help them assess the condition and extent of the debris.

They say it will be a delicate operation, citing the possibility that the robot may get stuck in piping or on other structures and become irretrievable.

The latest probe follows a robotic survey into the No.2 reactor earlier this year.

https://www3.nhk.or.jp/nhkworld/en/news/20170310_10/

TEPCO to examine inside of Fukushima No. 1 reactor Tues. with robot

The operator of the disaster-struck Fukushima Daiichi nuclear power plant said Thursday it will attempt to examine the inside of the No. 1 reactor next Tuesday using a remote-controlled robot.

The move follows a botched attempt by another self-propelled robot to take a look inside the No. 2 reactor, which also melted down. That robot became unable to move when it encountered debris and eventually could not be retrieved.

These are the first attempts by Tokyo Electric Power Company Holdings Inc. to examine the insides of the wrecked reactors since the nuclear disaster triggered by a massive earthquake and ensuing tsunami on March 11, 2011.

http://english.kyodonews.jp/news/2017/03/462752.html

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

Robot probe of Fukushima reactor halted due to radiation caused glitch

Robot probe of Fukushima reactor halted due to glitch

An operation to prepare to examine the inside of the No. 2 reactor at the disaster-struck Fukushima Daiichi nuclear plant was halted Thursday due to a technical glitch, the plant operator said.

Tokyo Electric Power Company Holdings Inc. said it sent a robot with a high-pressure water nozzle into a containment structure housing the pressure vessel, but suspended the work after video images from a camera on the robot became dark.

TEPCO said high radiation levels may have caused the camera glitch. The camera was designed to withstand cumulative radiation exposure up to 1,000 sieverts. Previously the company said up to 530 sieverts per hour of radiation was detected within the reactor containment structure in late January. The radiation reading during the robot operation Thursday was 650 sieverts, TEPCO said.

http://english.kyodonews.jp/news/2017/02/457859.html

 

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In this image released by Tokyo Electric Power Co. (TEPCO), a remote-controlled “cleaning” robot, bottom, enters the reactor containment chamber of Unit 2 for inspection and cleaning a passage for another robot as melted materials are seen at Fukushima Dai-ichi nuclear power plant in Okuma town, Fukushima prefecture, northeastern Japan, Thursday, Feb. 9, 2017. The “cleaning” robot that entered one of three tsunami-wrecked Fukushima reactor containment chambers was withdrawn before completing its mission due to glitches most likely caused by high radiation.

Cleaner robot pulled from Fukushima reactor due to radiation

TOKYO (AP) — A remote-controlled cleaning robot sent into a damaged reactor at Japan’s Fukushima nuclear plant had to be removed Thursday before it completed its work because of camera problems most likely caused by high radiation levels.

It was the first time a robot has entered the chamber inside the Unit 2 reactor since a March 2011 earthquake and tsunami critically damaged the Fukushima Da-ichi nuclear plant.

Tokyo Electric Power Co. said it was trying to inspect and clean a passage before another robot does a fuller examination to assess damage to the structure and its fuel. The second robot, known as the “scorpion,” will also measure radiation and temperatures.

Thursday’s problem underscores the challenges in decommissioning the wrecked nuclear plant. Inadequate cleaning, high radiation and structural damage could limit subsequent probes, and may require more radiation-resistant cameras and other equipment, TEPCO spokesman Takahiro Kimoto said.

“We will further study (Thursday’s) outcome before deciding on the deployment of the scorpion,” he said.

TEPCO needs to know the melted fuel’s exact location and condition and other structural damage in each of the three wrecked reactors to figure out the best and safest ways to remove the fuel. It is part of the decommissioning work, which is expected to take decades.

During Thursday’s cleaning mission, the robot went only part way into a space under the core that TEPCO wants to inspect closely. It crawled down the passage while peeling debris with a scraper and using water spray to blow some debris away. The dark brown deposits grew thicker and harder to remove as the robot went further.

After about two hours, the two cameras on the robot suddenly developed a lot of noise and their images quickly darkened — a sign of a problem caused by high radiation. Operators of the robot pulled it out of the chamber before completely losing control of it.

The outcome means the second robot will encounter more obstacles and have less time than expected for examination on its mission, currently planned for later this month, though Thursday’s results may cause a delay.

Both of the robots are designed to withstand up to 1,000 Sieverts of radiation. The cleaner’s two-hour endurance roughly matches an estimated radiation of 650 Sieverts per hour based on noise analysis of the images transmitted by the robot-mounted cameras. That’s less than one-tenth of the radiation levels inside a running reactor, but still would kill a person almost instantly.

Kimoto said the noise-based radiation analysis of the Unit 2’s condition showed a spike in radioactivity along a connecting bridge used to slide control rods in and out, a sign of a nearby source of high radioactivity, while levels were much lower in areas underneath the core, the opposite of what would normally be the case. He said the results are puzzling and require further analysis.

TEPCO officials said that despite the dangerously high figures, radiation is not leaking outside of the reactor.

Images recently captured from inside the chamber showed damage and structures coated with molten material, possibly mixed with melted nuclear fuel, and part of a disc platform hanging below the core that had been melted through.

http://mainichi.jp/english/articles/20170210/p2g/00m/0dm/004000c

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