The Fukushima Daiichi accident has affected nuclear energy strategy in different countries in different ways and to different extents. Global community continued to discuss and update concepts and actions for continuous improvement of nuclear safety based upon excellent level of management in nuclear sectors. Some examples of outcomes in international organizations are discussed in this paper to contribute management systems to cope with complexity of the issues in Japan. Considering responsibility and impu...
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Management of Nuclear Safety from Global Viewpoints

Abstract This study proposes importance factors of components to optimize maintenance of a system. Cost Fussell Vesely (C-FV) parameter me asures the effectiveness of maintenance for total cost optimization. Absolute risk achievement worth (ARAW), which can be a good parameter to optimize maintenance based on risk, is estimated by multiplying RAW value with non-reliability. Correlation between these factors and o ptimized maintenance methods is compared and discussed from the viewpoints of improvement of t...
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Study of Maintenance Planning Using Cost Importance

The recent situation of nuclear power generation gradually requires not only the economic viewpoint but also even greater efforts in accurate evaluations on safety and availability issues. Accordingly, assessments on the integrity of structural components are critical both now and in the future. Structural materials which suffer from age-related degradations especially should have methods to evaluate degradations due to changes in material properties. It is clear that conventionally used extrapolations of...
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Integration of modeling, database and inspection technique for the prediction of the material behavior under irradiation

Abstract: This paper discusses a development of the quantitative method to evaluate the reliability for the maintenance plan with respect to the risk impact both for Core Damage Frequency and Plant Trip Frequency. The quantitative approach includes the considerations for the effect of the Condition Based Maintenance (CBM) changing in addition to the Time Based Maintenance (TBM), and the reliability for the maintenance plan is evaluated using the actual plant-specific maintenance information collected ...
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A Study on the Reliability Evaluation Method for Maintenance Planning Using Risk Information

This paper discusses an improvement of the quantitative method to evaluate the reliability for the maintenance plan with respect to the risk impact both for CDF (Core Damage Frequency) and Plant Trip Frequency. The quantitative approach includes the considerations for the effect of the Condition Based Maintenance (CBM) changing in addition to the Time Based Maintenance (TBM), and the reliability for the maintenance plan is evaluated using component failure rate which is presumed from experimental maintena...
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A Study for the Reliability Evaluation Method for the Maintenance Plan Using the Risk Information II : - Part1 : The evaluation Method of failure rate based on degraded state analysis of component part ?

This paper discusses an improvement of the quantitative method to evaluate the reliability for the naintenance plan with respect to the risk impact both for CDF (Core Damage Frequency) and Plant T rip requency. The quantitative approach includes the considerations for the effect of the Condition Based Taintenance (CBM) changing in addition to the Time Based Maintenance (TBM), and the reliab ility for the naintenance plan is evaluated using component failure rate which is presumed from experimental naintena...
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A Study for the Reliability Evaluation Method for the Maintenance Plan Using the Risk Information II? Part 2: An application example of the evaluation method of failure ratebased on degraded state analysis of component part ?

In this paper, we propose an advanced method to optimize maintenance in complex systems compose d of many components which can degrade under service. Total lifetime cost of the system in nucl ear power plants is estimated adopting condition-based maintenance in addition to the time-bas ed maintenance considering both Fussel-Vesely factor and degradation behavior of the component....
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The Optimization Method of Maintenance in Large Scale Plant Systems Considering Time-Dependent Degradation of the Components

Che draft guideline for managing the leakage from seal portions of equipment in nuclear power plant has be en eveloped by the special research committee of Japan society of maintenology (ISM). In this paper, the o utline f this guideline is shown and the technical backgrounds and key points including leak management pr ocess, leak ate measurement methods, leak rate prediction method, acceptance criteria, etc. are discussed....
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Development of a Guideline for managing Leakage from Seal Portions of Equipment in Nuclear Power Plants

After Fukushima Daiich Accident, some international organizations have been discussed on importance of defense in depth (DiD), total comprehensive evaluation contained 14 Safety Factors in PSR (IAEA SSG-25) and HOF (Human and Organization Factors). The NRA allowed review by the IAEA Integrated Regulatory Review Service (IRRS) mission team, over the twice of 2008 and 2016. As a few recommendation examples on above these points to NRA, acquisition of human resources as able talented person and personnel...
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Human resource Development Activities lesson learned International standard after Fukushima Daiichi Accident towards a Proactive Nuclear Regulatory

Application of preventive maintenance technologies requires systematic development of information basis for database, knowledge-base and com mendable practice, which has been successfully accomplished in the OEC D/NEA SCAP project for stress corrosion cracking and cable degradation....
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Application of Preventive Maintenance Technologies: Based on the OECD/NEA SCAP Final Report