Fukushima cleanup chief urges better use of probe robot — The Seattle Times

” TOKYO (AP) — The head of decommissioning for the damaged Fukushima nuclear plant said Thursday that more creativity is needed in developing robots to locate and assess the condition of melted fuel rods.

A robot sent inside the Unit 2 containment vessel last month could not reach as close to the core area as was hoped for because it was blocked by deposits, believed to be a mixture of melted fuel and broken pieces of structures inside. Naohiro Masuda, president of Fukushima Dai-ichi Decommissioning, said he wants another probe sent in before deciding on methods to remove the reactor’s debris.

Unit 2 is one of the Fukushima reactors that melted down following the 2011 earthquake and tsunami.

The plant’s operator, Tokyo Electric Power Co., needs to know the melted fuel’s exact location as well as structural damage in each of the three wrecked reactors to figure out the best and safest ways to remove the fuel. Probes must rely on remote-controlled robots because radiation levels are too high for humans to survive.

Despite the incomplete probe missions, officials have said they want to stick to their schedule to determine the removal methods this summer and start work in 2021.

Earlier probes have suggested worse-than-anticipated challenges for the plant’s cleanup, which is expected to take decades. During the Unit 2 probe in early February, the “scorpion” robot crawler stalled after its total radiation exposure reached its limit in two hours, one-fifth of what was anticipated.

“We should think out of the box so we can examine the bottom of the core and how melted fuel debris spread out,” Masuda told reporters.

Probes are also being planned for the other two reactors. A tiny waterproof robot will be sent into Unit 1 in coming weeks, while experts are still trying to figure out a way to access the badly damaged Unit 3.

TEPCO is struggling with the plant’s decommissioning. The 2011 meltdown forced tens of thousands of nearby residents to evacuate their homes, and many have still not been able to return home due to high radiation levels.

Cleanup of communities outside of the plant is also a challenge. The cost has reportedly almost doubled to 4 trillion yen ($35 billion) from an earlier estimate. On Thursday, police arrested an Environment Ministry employee for allegedly taking bribes from a local construction firm president, media reports said. ”

by Mari Yamaguchi, The Associated Press

source

Cleaner robot pulled from Fukushima reactor due to radiation — Beloit Daily News

” 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. ”

by Mari Yamaguchi

source with photos

JAEA opens Fukushima R&D center for decommissioning reactors — The Asahi Shimbun

” NARAHA, Fukushima Prefecture–The Japan Atomic Energy Agency officially christened its new facility here on Oct. 19 that will develop technologies to decommission the reactors at the crippled Fukushima No. 1 nuclear power plant.

The Naraha Remote Technology Development Center will conduct research to develop remote-control decommissioning technologies as radiation levels within the reactors remain too high for workers to enter following a triple meltdown in the aftermath of the 2011 Great East Japan Earthquake and tsunami.

The opening ceremony was attended by 105 people, including Prime Minister Shinzo Abe, science and technology minister Hiroshi Hase and Fukushima Governor Masao Uchibori.

“The decommissioning process is a lengthy one that will take up to 40 years,” Abe said. “This facility was set up to consolidate the world’s knowledge to face the unknown.”

Featuring a life-sized mock-up of a damaged reactor and virtual reality systems, the center will test new machines and methods to remotely remove nuclear fuel from the Fukushima plant.

Experts hope that research and development at the facility will lead to a reduction in the number of failures of devices deployed at the crippled plant.

Abe witnessed a demonstration of a new scorpion-shaped robot, which will eventually be deployed inside the No. 2 reactor at the Fukushima plant.

The Naraha center will also erect in March a life-sized model of a reactor suppression chamber located beneath the containment vessel that was damaged in the 2011 disaster. Because the containment vessel has to be filled with water to remove the melted fuel inside, researchers plan to first develop technology to patch up the container to prevent leaks.

The facility is also equipped with a virtual reality system that projects onto a screen a computer-generated world simulating the space inside the damaged reactor buildings. The interior layouts of the crippled buildings are based on data collected by remote control robots deployed at the plant.

The technology will devise routes in removing melted fuel, along with coming up with methods to minimize the amount of radiation that workers will be exposed to.

The JAEA is also setting up a facility in Okuma to monitor the amount of radioactive materials inside the plant grounds. A total of 85 billion yen ($711.4 million) will be used to build the two JAEA facilities.

“There are still 100,000 people evacuated from the disaster,” said Toshio Kodama, JAEA president. “We hope to fulfill the role the JAEA is meant to play in the decommissioning process.” ”

source

Updated 7/7/2015: ‘Scorpion’ robot hopes to succeed where the snake-bots failed — News.com.au; New ‘scorpion’ robot will inspect Fukushima reactor this summer — Paleofuture

July 7, 2015, News.com.au:

” A NEW robot that raises its tail like a scorpion is scheduled to look at melted nuclear fuel inside one of the three wrecked Fukushima reactors in Japan.

Toshiba Corp., co-developer of the “scorpion” crawler that was demonstrated today, said the robot will venture into the Unit 2 reactor’s primary containment vessel in August after a month of training for its handlers.

But even metal and silicon cannot hold up to the intensity of radiation within a nuclear reactor for long.

The robot has enough radiation tolerance to allowing it to stay about 10 hours inside the Unit 2 reactor.

Toshiba officials say they hope the robot can capture images of deeper areas of the vessel, though the primary focus is the platform area, so they can design a more suitable robot that can go deeper into the vessel.

Insider View

Officials hope the robot can see the fuel in the pressure vessel in the middle of the reactor. The position of the toppled fuel rods hasn’t been located exactly and studied because of the high radiation levels.

The scorpion robot is the second to enter a primary containment vessel, after “snake” robots were sent in April inside the worst-hit Unit 1. One of the two robots used in that reactor became stuck and had to be left behind, and neither was able to spot the melted fuel debris.

This time, the scorpion crawler, which is 54 centimetres long when extended, will enter through a duct designed as a passageway for fuel rods. Toshiba has no back up machine.

The robot’s entry is just the beginning of the reactor investigation required before the most challenging task of removing the melted fuel.

The difficult work of decommissioning the Fukushima plant damaged by the 2011 earthquake and tsunami will take decades.

High Hopes

During the demonstration at a Toshiba lab near Tokyo, the robot slid down a railing as it stretched out like a bar, with a head-mounted LED showing its way. After crawling over a slight gap and landing on a metal platform, the robot lifted its tail, as if looking up at the bottom of the control rod drive, a structure above the platform where some melted nuclear fuel might be left.

The scorpion also demonstrated it can roll back upright if it hits an obstacle and rolls over. The ability comes from a tail joint in the middle that bends.

One operator controls the robot with a joystick, and another monitors a video feed from the robot and other data. At the Fukushima plant, the robot will be operated remotely from a command centre in a separate building.

The work is planned for a full day. ”

source with video and photos

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Posted July 2, 2015, Paleofuture:

” When the 2011 earthquake in Japan damaged the Fukushima nuclear power plant, teams scrambled to find a robot that could go where humans couldn’t. In many ways those robots failed, and ever since, there has been a focus on creating robots that can get the job done. Enter Toshiba’s “Scorpion” robot, which will make its way inside the power plant this August.

The Scorpion is just 21 inches long and is operated by remote control. The robot has cameras on both front and back, as well as LED lights to help light the way. What is Scorpion looking for? Fuel amongst the debris, which will give teams a better sense of how the decades-long clean-up at the reactors should proceed.

Back in April, teams sent a snake-like robot inside one of the nuclear reactors but didn’t find what they were looking for. That robot stopped working after just three hours in one of the reactors. A second snake-bot was sent in a few days later but that one stopped working in short order as well.

The Scorpion is said to be specially designed to operate in the highly radioactive environment. Teams expect the robot to be able to function for 10 hours inside the plant. But we’ll have to wait and see.

The main focus of last month’s DARPA Robotics Challenge was to develop robots for emergency scenarios. And that competition, along with the relatively primitive capabilities of a robot like Scorpion show that we have quite a long ways to go before robots are performing the human-like tasks that we’d like them to in disaster scenarios. ”

source with photos

Also read about the DARPA Robotics Challenge in this Japan Times article, “Robots compete in Fukushia-inspired U.S. challenge