Packbot enters Fukushima Daiichi unit 3’s reactor building for the first time since the accident. (Click to enlarge.)
When many of us think of robots, images of Wall-E, Optimus Prime, R2-D2 and other droids from our favorite science-fiction movies come to mind. However, robots have many critical real-life functions, including detecting bombs in war zones and assisting in recovery efforts at disaster areas. More recently, robots have been utilized to clean up the reactors at Tokyo Electric Power Company’s (TEPCO) Fukushima Daiichi nuclear power plant in Japan. These remotely-controlled vehicles have removed debris from the site and measured radioactivity in hazardous zones, all while transmitting video and information back to workers who monitor the data from a safe distance. The robots are master scouts, mapping radiation and taking samples to ensure that conditions are safe for their human colleagues.
Robots were first deployed at Fukushima just weeks after a powerful earthquake and tsunami devastated the northeast coast of Japan and damaged the nuclear energy facility. Massachusetts-based company iRobot deployed four robots to the site, including the lightweight, versatile PackBot 510 and the heavy-duty Warrior 710. These unmanned vehicles were built for the battlefield but modified to navigate and endure the hazardous conditions at the facility. The PackBot came equipped for the mission with the company’s full HazMat kit, which enabled it to measure temperature and detect gamma radiation, explosive gases and toxic chemicals, and feed all of that data to TEPCO controllers in real-time.
Kageharu Oikawa, deputy manager of the mechanical system group in the Fukushima Daiichi Stabilization Center, described the PackBot as an “all-around player whose best attribute is its flexibility.” The machine’s manipulator arm performed a variety of useful tasks, including opening the doors to reactor buildings for the first time since the accident, about one month after the earthquake and tsunami. It also removed debris, absorbed contaminated water using diapers and measured radiation in specific locations.
“We put a dosimeter on the top of the robot’s arm, enabling us to detect a radiation dose rate at a pin-point location,” said Oikawa.
Once the PackBot entered the reactor buildings and determined that conditions were safe, humans were soon allowed to work inside.
“The information gained from the robots was incredibly useful,” said Oikawa. “They allowed us to eliminate the fear of the unknown.”
The 450-pound Warrior also was used at the site. It has the strength to tow a pickup truck, but is also nimble enough to perform dexterous tasks with its two-meter-long mechanical arm. The Warrior at Fukushima removed large debris in the reactor buildings and cleaned up radioactive material from the floors with a vacuum cleaner and deck brushes attached to its powerful arms.
The North American branch of the global defense technology company QinetiQ also sent robots to Japan, including the TALON, which navigated through the rubble outside the plant to measure radiation levels, the Bobcat, which was used to lift heavy debris, and the 15-inch Dragon Runner, designed for missions in small spaces. According to Shin Yoshino, group manager of TEPCO’s Research and Development Center, the TALON was controlled by operators in shielded vehicles, thus reducing radiation dosages to workers by 60 percent and extending the amount of time they were able to stay at the site.
TEPCO expressed its gratitude for the quick deployment of robots to the site. Oikawa recalled working with technical support from the U.S. Army through Operation Tomodachi, a military unit that provided disaster relief to the Japanese government and people following the earthquake and tsunami.
“At that time, iRobot voluntarily offered robots to TEPCO and I was assigned to take them to Fukushima,” Oikawa said. “The PackBot was the first robot I encountered in my entire life. I can still remember how impressed I was by its sophisticated design and motion. iRobot engineers and their Japanese agents fully supported us during the introduction of robots, and even created a step-by-step instruction video guide for our operators.”
Photo taken by the Quince robot while surveying the 5th floor of Fukushima Daiichi unit 2. (Click to enlarge.)
Approximately three months after the accident, TEPCO brought another robot to the site to assist with the recovery effort: the Quince. Experts at Japan’s Chiba Institute of Technology, Tohoku University and the International Rescue System Institute jointly developed this robot. It is highly mobile and has been used for dust sampling as well as radiation dose and temperature measurements inside the facility’s reactor buildings.
The robots used at Fukushima proved their value by working in highly radioactive environments. However, this was not the first time that robots were used at a nuclear energy facility.
The Three Mile Island nuclear energy facility, located in Pa., used six robots over a 10-year period for its recovery efforts. Since Fukushima, other companies, such as Progress Energy, are pursuing using robots as part of their day-to-day operations to better protect plant workers.
“While only wired communication was used at Three Mile Island, today’s robots have wired-wireless hybrid communications,” Yoshino said. “Advancements in communication technologies have enabled the robots to send large amounts of data, allowing us to get more information than in the past.”
The information collected by the robots has assisted TEPCO in determining the next steps in its long-term restoration plan. In addition to verifying that conditions are safe for plant employees, the robots also collect data critical to deciding how long workers can stay inside certain areas of the plant, how many people will be needed to perform certain tasks, and if modifications are needed for the recovery plan.
Today, two PackBots, one TALON and one Quince are still currently being used at Fukushima, collecting critical data from difficult to reach areas, and the company continues to look for innovative ways to use robots in its recovery efforts.
More about the QinetiQ Robots
QinetiQ donated about $1 million worth of equipment to the recovery efforts at Fukushima, including three TALONs, two Dragon Runners and equipment that turns Bobcat loaders into unmanned vehicles capable of lifting debris without an operator.
The Department of Energy’s Idaho National Laboratory modified one of the TALONs so that it is outfitted with radiation-hardened cameras, GPS, night vision and CBRNE — Chemical, Biological, Radiological, Nuclear and Explosive — detection kits. With the kits, it can identify more than 7,500 environmental hazards and has sensing capabilities from up to 3,280 feet. The TALON has been used in military operations in Iraq and Afghanistan and for decontamination at Ground Zero.
More about the Quince
The Quince is the only unmanned vehicle that has been able to climb the narrow 90-cm-wide, 40-degree-steep stairways inside Fukushima’s reactor buildings to measure radiation levels where the spent fuel pools are located. TEPCO is using the data and video taken by Quince on the top floor of Unit 2, where radiation levels are still too high for workers to enter, to prepare for the removal of spent fuel rods from the spent fuel pool. The robots are designed to withstand more than 200 Sieverts of radiation, and can move easily over uneven debris.
Experts at the Chiba Institute of Technology performed several tests on the robot before sending it to Fukushima, including making it navigate a stairway built to mimic the conditions of those in the facility’s reactor buildings, fall off a table more than 400 times to see which part of the robot broke first, and crash into walls to see how resistant it was to shock.
TEPCO used the first Quince at the site from June until October, before it became stranded inside Unit 2 due to a loss of communication caused by a tangled cable. Engineers modified the next two robots, fitting them with a fully automated wire reel system, which rewinds their 500-meter-long cables. Quince2 also has a remote dust sampling system and Quince3 has a 3D laser scanner.