Abstract: This study reports the development of a new microwave probe for the nondestructive testing of a pipe. Three-dimensional finite element simulations are carried out to optimize the profile of a microwave probe, whose results show that a probe with elliptic profile enables smaller reflection at the probes as well as much better single-mode propagation inside the pipe than conventional ones. Experimental validations are carried out using a straight brass pipe with an inner diameter of 39 mm and...
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Enhancement of microwave nondestructive testing method for the inspection of pipes by optimizing the microwave probe profile

The purpose of this study is to perform cost assessment of nuclear fusion reactors in order to draw up commercial plants. A fusion reactor may have a complex configuration to achieve high beta value, which leads to low and instable availability when maintenance is taken into account. Therefore, reactor's availability must be evaluated with considering the influence of the configuration complexity. Furthermore the availability has the strong impact on COE(Cost of Electricity), that is, a fusion reactor with ...
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Cost assessment of demo fusion reactor with considering maintenance

Abstract: Outlines of, and the empirical observations from, an action research project aiming at improvement of relationship between nuclear community and the public have been reported in this paper. Ultimate goal of the project is effective reduction of social construct risk of nuclear power plants. As an initial approach to the goal, a proactive information provision scheme has been designed based on the knowledge acquired during our previous attemp t of public communication named repetitive dialogue for...
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Proactive Information Provision for Reducing Social Construct Risk of Nuclear Facility

In this study, a new simulation method is developed for optimization of maintenance strategy in NPP as a multiple-objective optimization problem (MOP). The result of operation is evaluated as the average of the following three measures in 3 000trials: Cost of Electricity (COE) as economic risk, Frequency of unplanned shutdown as plant reliability, and Unavailability of Regular Service System (RSS) and Engineering Safety Features (ESF) as safety measures. The following maintena nce parameters are considered...
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Development of an evaluation method for optimization of maintenance strategy in commercial plant

Abstract The purpose of this study is to develop a method for quantitative evaluation of the running cost and safety in a Nuclear Power Plant (NPP). A new model for numerical evaluation is proposed based on the concept where the four issues such as Cost of Electricity (COE), maintenan ce cost, loss by the failures, and several risks are evaluated statistically by using the Monte Carlo simulation. The results show different d ependence on the parameters used in the model. These results would be useful to d...
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Development of quantitative evaluation method for the cost and safetyin maintenance plan of Nuclear Power Plant

This study proposes a method to fabricate an artificial defect that is almost identical to stress corrosion cracking from the viewpoint of electromagnetic nondestructive evaluations. The key idea is to realize a region having electrical resistance embedded inside a conductive materials using solid state bonding. A rough region is introduced into the surface of the materials to be bonded so that the region is partially bonded to realize electrical resistance. Experimental demonstrations are carried out...
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Fabrication of imitative stress corrosion cracking specimens suitable for electromagnetic nondestructive evaluations using solid state bonding

This study proposes a method to fabricate artificial defects that is almost identical to stress corrosion cracking from the viewpoint of electromagnetic nondestructive evalua tions. The key idea is to realize a region having electrical resistance embedded inside a conductive materials using solid state bonding. A rough region is introduced into th e surface of the materials so that the region is partially bonded to realize electrical resistance The validity of the method is demonstrated using type 316L aus...
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Fabrication of imitative stress corrosion cracking specimens suitable for electromagnetic nondestructive evaluations using solid state bonding

1. はじめに 新規制基準があれば、 福島事故は回避できたか? 東北大学 大学院工学研究科 橋爪 秀利 Hidetoshi HASHIZUME 東北大学 大学院工学研究科 青木 孝行 Takayuki AOKI 年 11 月までに 8 回に亘って実施された同検討会の検討成 日本保全学会では、 これまでに福島原発事故の教訓を踏 まえて 「津波対策評価ガイドライン 1」 及び 「過酷事故対策評 価ガイドライン 2」 を開発し、発行している。 これらのガイドライ ンを開発した検討会において繰り返し議論になった論......

In nuclear power plants, there are many T-junctions at which different temperature fluids are mixed. When the fluids with different temperature are mixed, temperature fluctu ation in fluids reachs wall and high-cycle heat fatigue occurs. Depending on amplitude and frequency of temperature fluctuation, it could lead to pipe rupture accident at wo rst. In addition, in case of the T-junction with 90-degreee bend at upstream, there is higher risk for pipe rupture accident due to secondary flow which arises in ...
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Effect of secondary flow generated in 90-dgree bend upon high-cycle thermal fatigue in a mixing tee

Abstract. This study discusses a suitable numerical modeling of a thermal fatigue crack from the viewpoint of eddy current testing. Five artificial thermal fatigue cracks, introduced into type 304L austenitic stainless steel plates with a thickness of 25 mm, are prepared; and eddy current inspections are carried out to gather signals using an absolute type pancake probe and a differential type plus point probe. Finite element simulations are then carried out to evaluate a proper numerical model of the...
英字タイトル:
Numerical modeling of thermal fatigue cracks from the viewpoint of eddy current testing