TOKYO, March 27-Results of the successful robotic exploration of the Unit 1 Primary Containment Vessel at Fukushima Daiichi were addressed at a press conference today, along with photos and video recordings taken by the robot inside the reactor:
･Deposits were found at the bottom of the PCV and on piping. (The deposits will be analyzed by examining the images and taking samples.)
･Radiation dose levels decrease upon submerging into the water and rise again when nearing the floor.
･There has been little change in dose levels above the grating compared to the previous survey, (April 2015) and no significant damage was found to existing structures.
Chief Decommissioning Officer Naohiro Masuda summarized the results of the radiation readings and digital images obtained in the Unit 1 PCV. It will take more time to conclude whether fuel debris exists at the measured points or how far it is spread over the PCV basement. TEPCO will continue to examine the results and announce the findings as soon as they are available.
The Hitachi-developed "PMORPH" robot made several excursions into the PCV over a five-day period, completing its mission on March 22. Equipped with a dosimeter and waterproof camera, it took radiation readings and digital images at 10 different measurement points. For more information on the data released today, go to
During the PMORPH exploration period, various steps were taken to ensure there was no leakage of radiation from inside the PCV. No significant changes have been observed at the monitoring posts and dust monitors after the investigation, compared to the before since the radiation is shielded with thick concrete walls of PCV and separate steel walls. Real-time radiation data from the monitoring posts and dust-monitoring stations along the facility’s boundary are available on the TEPCO website at
One challenge in gathering data from the bottom of the Unit 1 PCV is the floating deposits in the standing water that obscure photography. For that reason, the next step in the Unit 1 exploration will be the extraction of a water sample to help engineers determine the precise nature of the floating deposits and devise a strategy to obtain clear pictures.
The robotic exploration of Unit 1 is part of the long-term preparations for the eventual removal of fuel debris from the March 2011 accident.
About TEPCO Group
Tokyo Electric Power Company Holdings, Inc. (TEPCO Holdings) is Japan's largest power company group, holding three independent business entities: TEPCO Fuel & Power, Inc., TEPCO Power Grid, Inc., and TEPCO Energy Partner, Inc. As a group, it generates, distributes, and sells electricity and other types of energy principally to the Kanto metropolitan area, which includes Japan's two most populous cities, Tokyo and Yokohama. Its 33,000 employees are committed to providing safe, reliable power to its 29 million customers as well as fulfilling its responsibilities to the communities of Fukushima. (As of April 1, 2016)
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