Robot Probe « nuclear-news

Robot Probe Forays Inside Fukushima Daiichi Reactor 1

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 dunrenard | Fukushima 2017 | Fukushima Daiichi, Reactor 1, Robot Probe | Leave a comment

Robot probe of No.1 reactor started on Saturday

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 dunrenard | Fukushima 2017 | Fukushima Daiichi, Reactor 1, Robot Probe | 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 dunrenard | Fukushima 2017 | Fukushima Daiichi, Reactor 1, Robot Probe | Leave a comment

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

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 dunrenard | Fukushima 2017 | Fukushima Daiichi, Reactor 1, Robot Probe | 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

hjmlkmùlm.jpg

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 dunrenard | Fukushima 2017 | Fukushima Daiichi, Glitch, reactor 2, Robot Probe | Leave a comment