Removal of large rubble from the roof and walls of the reactor building collapsed due to the hydrogen explosion and dose rate reduction for human workers to begin preparation work shall be accomplished for retrieval of spent fuel from the spent fuel pool at Fukushima Daiichi Nuclear Power Station Unit3. This paper describes the method of survey and evaluation, decontamination and shielding method for dose rate reduction on operational floor of Fukushima Daiichi Nuclear Power Station Unit3....
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Approach to Dose Rate Reduction for Retrieval of Spent Fuel from Spent Fuel Pool at Fukushima Daiichi Nuclear Power Station Unit3

Since the 2011 Great East Japan Earthquake, Toshiba Energy Systems & Solutions Corp. (Toshiba) has accomplished various tasks in preparation for the upcoming fuel removal operations at the Fukushima Daiichi Nuclear Power Plant (F-1) Unit 3. In November 2015, TEPCO and Toshiba removed large rubble (e.g. Fuel handling machine) that had been sitting inside the spent fuel pool [SFP] as a result of the hydrogen explosion. Currently, Toshiba continues to work on the projects related to fuel removal from the SFP, ...
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Effort aimed at removal of stored fuels from SFP in Fukushima Daiichi Nuclear Power Station

At the Fukushima Daiichi Nuclear Power Station, it is critical to (1) confirm the presence of fuel debris inside the PCV that could be melted fuel as a result of the hydrogen explosion followed by the accident; and (2) conduct in-depth investigations prior to decommissioning. However, the conditions inside the PCVs were unknown. Under this circumstance, International Research Institute for Nuclear decommissioning (IRID) and Toshiba ESS jointly developed devices that can access to the lower part of a PCV and...
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Development of Remotely-Operated Devices for Investigation Inside Primary Containment Vessel (PCV) of Fukushima Daiichi Nuclear Power Station Unit 2 and 3 and Survey Results

Recently, an application target of the phased array ultrasonic testing (PAUT) has been extended. However, it was known that PAUT was difficult to apply to components with complex and high damping materials such as cast austenitic stainless steel (CASS). The Authors have developed shape adaptive beam forming PAUT system for complicated shape parts and comprehensive PAUT conditions analysis system for CASS. Each PAUT systems based on full matrix capture (FMC) technique. In order to enhance an applicability of...
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UT application examination for complicated shape part of cast austenitic stainless steel

It is important to improve both plant safety and plant operability simultaneously in nuclear power plants (NPPs). “On-Line Maintenance (OLM)” is one of solutions for this issue. This paper proposes “Application rules of OLMs for systems & components against Severe Accidents” based on IRIDM (Integrated Risk Informed Decision Making). In this proposal, implementation of OLMs should be decided by CDF (Core Damage Frequency) and CFF (Containment Failure Frequency) under system configuration during OLM, and comp...
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Application rules and future tasks of On-Line Maintenance for systems & components against Severe Accidents

Additional RPV surveillance test are required to extend the operation license of nuclear power plants. Since the number of surveillance test specimens is limited, it is important to establish a reconstitution technique of the surveillance test specimen. Applicability evaluation of reconstituted impact test specimen by electron beam welding for RPV surveillance test were conducted, and it was confirmed that reconstituted impact test specimen was applicable to RPV surveillance test. ...
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Applicability Evaluation of Reconstituted impact test specimen by electron beam welding for RPV Surveillance Test

An electrical isolation planning system is now under development to improve the efficiency of operating and maintaining nuclear power plant. The system automates electrical isolation planning, and evaluates the influence of the isolation plan. It also equips an algorithm that automatically adds information such as circuit connection and device attribution to the original paper-drawing. A demonstration of automatic isolation planning was conducted that used actual plant drawings. The system successfully repr...
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Development of Electrical-Isolation support system

From a viewpoint of safe operation and the improvement in an operating ratio of equipment, Efficient maintenance engineering and inspection work is needed. Therefore, we developed a patrol system using 360-degree camera and self-localization technology. A 360-degree camera which can photo the image of all the directions was used for this system. It can record the spherical image of an inspection worker, and enables the inspection image of the direction to need. Moreover, early detection of change of an on-s...
英字タイトル:
Development of a Patrol System using 360-degree view