Toshiba Energy Systems & Solutions Corporation
Toshiba Plant Systems & Services Corporation
Toshiba Power Systems Radiation Techno-Service Corporation
Fukushima, Japan—Toshiba Group received a certificate of appreciation from the Prime Minister of Japan for works carried out with subcontractors at Fukushima Daiichi Nuclear Power Station. The works are “Reducing radiation doses on the reactor building’s operating floor*1 of the Unit3 for the preparation of the removal of fuel from the spent fuel pool.”
Meanwhile, Toshiba Group received a certificate of appreciation from the State Minister of Economy, Trade and Industry for investigation of “the interiors of the Unit 2 and Unit 3 primary containment vessels (PCVs)”.
The reduction of the radiation dose on the reactor building’s operating floor of the Unit 3 was considered indispensable toward the removal of fuel from the spent fuel pool. Toshiba Group carried out radiation dose reduction measures between October 2013 and January 2017, which were a combination of decontamination and installation of shields. We successfully reduced the extremely high air radiation rate of several hundred mSv/h down to 1 mSv/h—an air radiation rate in which manned work is possible. Dose reduction on the highly-radioactive operating floor was achieved while thoroughly reducing radiation exposure through such means as the use of remote-control technology. This was highly regarded, resulting in the certificate of appreciation.
As a member of the International Research Institute for Nuclear Decommissioning (IRID), Toshiba Group has been investigating the interiors of the PCVs of Fukushima Daiichi Nuclear Power Plant Unit 2 and Unit 3. The aim is to obtain an understanding of their status to enable future removal of fuel debris. A device consisting of a guiding pipe and telescopic guiding pipe entered Unit 2 in January 2018 and succeeded in shooting images of deposits, believed to be fuel debris, at the bottom of the pedestal*2 area.
Meanwhile, a small, submersible robot entered Unit 3 in July 2017, succeeding for the first time in investigating the state inside the pedestal area.
The development of the remote device and robot, which operated reliably under severe conditions where access was difficult and radiation levels were high, and Toshiba Group’s success in obtaining important information that contributed to the planning of fuel debris removal were highly recognized.
Toshiba Group, cooperate with Tokyo Electric Power Company Holdings, Incorporated, IRID and subcontractors, will continue to contribute tothe decommissioning of the Fukushima Daiichi Nuclear Power Station.
*1 Operating floor: The uppermost floor of the nuclear reactor building. During periodic inspections, operations such as refueling are carried out there.
*2 Pedestal: A concrete structure that supports the nuclear reactor pressure vessel.
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