The 2011 off the Pacific coast of Tohoku Pacific Earthquake and the Tsunami gave the serious damage to the Fukushima-Daiichi Nuclear Power Plants (NPPs). The accidents occurred in Unit 1, 2, 3 and 4. It is said that the height of tsunami attacked Fukushima NPP was more than 14m. After 50 minutes from the automatic shut-down, tsunami a ttacked the NPPs in Fukushima Daiichi NPPs. For example, the Unit 1 lost A/C power caused the loss of water injection function; it made the core meltdown and unusual increase...
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Lessons Learned from the TMI-2 Accident and Chernobyl Nuclear Disaster for Nuclear SafetyInnovation

１．はじめに　平成18年9月に、経済産業省原子力安全・保安院が「検査のあり方に関する検討会」にて原子力発電所におけるより科学的かつ合理的検査制度の実現に向けた今後の取り組みを取りまとめた「原子力発電施設に対する検査制度の改善について」を提示しました。今回は、取りまとめられた取り組みのうちの一つである「保全プログラムに基づく保全活動に対する検査制度の導入」について簡単に説明させていただきます。　２．個々のプラントの特性に対応した検査の必要性　我が国では実用発電用原子炉が現在５５基稼動していますが、それぞれの......

1．はじめに21世紀の幕開けと相前後して、原子力産業を含む 様々な産業界において、組織としての安全性向上への取り組みの実効性に疑問を投げかけるように、いわゆる「組織事故」が多発した。すなわち、1999年２月の横 浜市大の患者取り違え事故に始まり、核燃料転換工場 （JCO）臨界事故、H2ロケット打ち上げ失敗と続き、2000年には雪印乳業の食中毒事件、京福電鉄の列車衝突、三菱自工リコール隠しが発生し、最近になっても、三重県廃棄物発電（RDF）火災事故、新日鉄名古屋での高炉爆発、ブリジストン栃木工場火災、出光北......

Cosmic-ray muon is high energy leptons generated in the earth’s atmospheres as results of cosmic-ray proton/electron bombardment. Muon scattering method has been developed for nuclear security applications using its highly penetrative feature and sensitivity for high Z-materials. This study introduced the measurement of small nuclear reactor which consists of UO2 fuels and simulation study of container scanning system by muon scattering method. These results showed effectiveness of muon scattering metho...
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Nuclear Security Applications of Cosmic-ray Muon 杉田 宰 Tsukasa SUGITA Non-Member

Muon tomography has recently been put to practical use for nondestructive testing of shipping container. But it can’t be used in a high dose environment(～1mSv/h) without shielding. So, we are developing high dose tolerant muon track measurement system using spark chamber technology. In this paper, the result of simulation is described. We found that it is necessary to use 10cm-square scintillation counters and its pulse width is in 300ns. We confirmed this design is achievable to use in high dose rate(...
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High dose tolerant nondestructive testing using muon tomography

We proposed a novel sodium leak detection technique based on laser spectroscopy to improve the reliability of sodium le ak monitoring. In this technique, sodium atoms are excited into a first excitation level by atmospheric plasma before l aser spectroscopy. The detection limit concentration was preliminarily evaluated to be comparative to the sodium aeros ol detector. We confirmed that the maximum of 3p level population can be achieved at a proper plasma burning condition....
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Development of a Sodium Leak Detector based on Atomic Spectroscopy using a Laser Diode

After Fukushima daiichi nuclear accident, it becomes more important risk communication with the public. In discussions with the public in nuclear safety, communication and discussions on risks that not only nuclear risks also social risks are important. Differences in viewpoints, understanding, and thought about risks become communication difficult. We need to discuss risks fairly, appropriately with the public and reduce total social risks. ...
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For Discussions with the Public for the Safety of Nuclear Power -Discussion with the Public -

As one of top countries in per capita GDP, Switzerland has been keeping up a society with high resilience for historical events since 1815 after Napoleonic wars. In this presentation, the resilient history in the permanent neutral country is briefly described and then the resilient use of nuclear energy is also described as a country of less CO2 emission in advanced countries. The atomic energy basic law in Japan clearly declares the democratic, self-motivating and public opening principles for use of nuc...
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For Discussions with the Public for the Safety of Nuclear Power - For Making a Resilient Society with Sustainability-

Approximately 20,000 valves are installed in each nuclear power plant and the inspection by TBM had been adapted mainly. Wit h the application of the new inspection system that has been implemented from January 2009, the need for adapting method con forming to CBM has been examined to optimize the conservation activities in the nuclear power plants. The method of conditio n monitoring for motor-operated valve with the new diagnosis device and the effectiveness are to be addressed in the speech....
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Condition Based Maintenance of the Motor Operated Valve in Nuclear Power Plant

This paper describes localization and cable handling me thod as the underlying techniques for underwater surveyrobot. Map matching method comparing cross-sectional hape data cut from a 3-D CAD with structural shapesmeasured by a range sensor is proposed as the localiza tion. The cable handling system mounted to a robot isdeveloped to operate the cable remotely. Some experime nts to evaluate performance of the proposed techniqueswere implemented at mock-ups of a reactor building and he real field. As a resu...
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Development of underlying techniques for underwater survey robot to decommission nuclear power plants