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Robotic Surveys Having Trouble Inside Fukushima Reactor No. 1
Six years after what is known in Japan as the Great Japan Earthquake, which triggered a devastating tsunami and severely damaged Tokyo Electric Power Company (TEPCO)'s Fukushima Daiichi Nuclear Power Station, the company is dealing with a new challenge inside that power plant: It hasn't been successful at using robots in the No. 1 reactor to collect data on the locations of melted nuclear fuel and radiation levels, The Asahi Shimbun reported March 24.
The newspaper's website reported that Japan's Nuclear Regulation Authority is recommending using a different survey method after TEPCO said March 23 that a robot attempt March 18-22 failed to deliver a camera to locations where images of nuclear fuel debris could be taken, and that other "recent investigations utilizing robots controlled remotely generated few findings and were quickly terminated."
TEPCO and its employees and contractors marked the sixth anniversary of the earthquake and tsunami earlier this month. "We remember the many people who lost their lives and family members as the result of the earthquake and tsunami," said TEPCO Holdings President Naomi Hirose, "and we also remember those whose lives were disrupted by the accident at Fukushima Daiichi. They are a constant inspiration to our work to do everything we can to safely decommission the site and help revitalize the Fukushima region."
He praised the "tireless" contributions from thousands of TEPCO workers and workers from other companies and countries to decommission the plant. "During these six years, we have progressed from emergency stabilization of the site to progress in long-term decommissioning," he said, citing reduced radiation at the site, improved working conditions, advances in water treatment and management, and information obtained from inside the Unit 2 reactor. "“These advances were made possible by the hard work and dedication of thousands of people, whether at the site or developing robot technology, or in laboratories or elsewhere," he said. "This progress represents the first steps of a long journey. Our commitment to the people of Fukushima will continue to inspire every step we take along that path until the work is complete."
The newspaper's report said the robot used inside the No. 1 reactor is equipped with a radiation dosimeter. "At one location, the robot succeeded in placing a camera, which is combined with a dosimeter, to a depth 0.3 meter from the containment vessel floor," it said. "The probe measured underwater radiation levels from 3.0 to 11 sieverts per hour during the five-day survey. But it was unable to take images of the debris in the water. TEPCO and the government hope to start removing molten nuclear fuel from 2021. But they have yet to collect information on the location, amount and condition of the melted fuel."