Toshiba and TEPCO completed the removal of large debris from the spent fuel pool (SFP) in November 2015. The large debris had been an obstacle to start the fuel debris removal work and had been necessary to be removed quickly in terms of risk reduction. Continuously, Toshiba and TEPCO are preparing for removal of small debris and spent fuels. Also, Toshiba and IRID are investigating of PCV interior and working in research and development to determine construction methods considering amount, location an...
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Effort aimed at removal of stored fuels from SFP and fuel debris inside PCV in Fukushima Daiichi Nuclear Power Station

Abstract: National Institute of Advanced Industrial Science and Technology (AIST) and Honda R&D Co., Ltd. (Honda) have developed a robot to survey high and complex areas in the reactor buildings at Fukushima Daiichi nuclear power station. The high-access survey robot consists of a high-area accessible crawler type work platform and a survey arm installed on top of the platform, both of which can be remotely controlled using an intuitive graphical user interface. The robot has been deployed three times ...
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High-Access Survey Robot for Fukushima Daiichi Nuclear Power Station

This study proposes a numerical analysis method for evaluation of strength properties related with mater ial control and material maintenance. The method using generalized Voronoi diagram for modeling of hete rogeneity of grain shape is proposed. Effect of grain shape on strength properties is analyzed by the fi nite element method. ...
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Investigation of Material Control and Material Maintenance Method by Evaluation of Strength Properties Considering Grain Shape

Abstract Surface finishing methods, such as Water Jet Peening (WJP), have been applied to welds in some major components of nuclear power plants as a counter measure to Primary Water Stress Corrosion Cracking (PWSCC). In addition, the methods of surface finishing (buffing treatment) is being standardized, and thus the buffing treatment has been also recognized as the well-established method of improving stress. On the other hand, the long-term stability of peening techniques has been confirmed by acc...
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Prediction method of long-term reliability in improving residual stresses by means of surface finishing

Flow Accelerated Corrosion (FAC) is one of the issues to be noticed considerably in plant piping management. For the integrity and safety of t he plant, the wall-thinning and thinning rate due to FAC should be clely predicted in pipe wall inspection. In this paper, we study FAC fro m the view point of flow dynamics. The mass transfer coefficient is estimated by the numerical simulation inside the bent. Changing the Reynol ds number, the peak location of mass transfer coefficient and its maxim value is eval...
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Mass Transfer and Shape Factor in Complicated Flow Field

先行する米国、スペイン及びフィンランドにおけるOLMの実施状況や、背景、規制要件、規制・産業界ガイダンス、安全管理手法及びOLMの効果等について概説する。...

Domestic light water reactors are expected to restart sequentially after given permission in condition to meet the new regulatory requirements. Since several safety related systems were added to the plants through the process of the new regulatory requirements, the numbers of components to be inspected, which is already a large amount, will increase even more after the restart. Effective measure will be required to command maintenance activities by reasonably assigning limited resource. The authors hav...
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Study on Fluid Leakage Behavior with Pipe Failure

Flow accelerated corrosion (FAC) is the major pipe wall thinning phenomena in power plants. The management of pipe wall thinning has been carried out to pipe elements such as elbow, orifice, etc. of the piping system in power plants. In piping system, it is known that several pipe elements which are connected in series may generate swirl flow. Therefore the arrangement of pipe elements is considered to affect thinning phenomena seriously. So the behavior of this swirl flow is one of the major research ...
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EFFECT OF SWIRL FLOW GENERATED BY THE COMBINATION OF PIPE ELEMENTS ON WALL THINNING PHENOMENA

Flow accelerated corrosion (FAC) is the major pipe wall thinning phenomena in power plants. The management of pipe wall thinning has been carried out to pipe elements such as elbow, orifice, etc. of the piping system in power plants. In piping system, it is known that several pipe elements which are connected in series may generate swirl flow. Therefore the arrangement of pipe elements is considered to affect thinning phenomena seriously. So the behavior of this swirl flow is one of the major research tar...
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Evaluation of mass transfer coefficient under swirl flowgenerated by the combination of pipe elements

Ultrasonic testing is difficult for cast stainless steel which is used as the material of main coolant pipes in pressurized water reactors, because of the ultrasonic scattering by the huge grain of the material. Therefore we performed ultrasonic testing for the axial fatigue crack on welding area in the test piece of the cast stainless pipe, using the double big-size ultrasonic probes which we developed. And we simulated the ultrasonic beam behavior using finite element ultrasonic propagation simulatio...
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Ultrasonic testing and simulation analysis by the large aperture transducer for axial crack in cast stainless steel pipe weld