Functional assessment of equipment, considering the aged degradation of material, maintenance and so on, is required in order to evaluate the soundness of nuclear power plant in operation. In this report, equipment probabilistic risk is dealt with as showing the soundness of equipment, and the ideas how to consider aged degradation and maintenance on probabilistic risk are showed. ...
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Equipment Probabilistic Risk Assessment Considering Aged Degradation and Maintenance

In this research, the new method to predict the near-future of the movie images captured by video camera based on the combination of t he Principle Component Analysis (PCA) and the Singular Spectral Analysis (SSA). In the normal condition of machines, the real-time ca ptured movie is supposed to correspond to the predicted one. If the error between the both becomes significantly large, it may suggest some anomalous motion of the machines. So the movie prediction method has a possibility of the sensitive an...
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Development of Anomalous Detection using Movie Prediction

In this research, a new method was developed to identify the _hand motion” of malicious sabotage behaviors. The Auto-encoder and Auto Associative Neural Network were applied for identification, and the time-series data of finger tips position were used as the training data of these Machine Learning. The identification reliability was more than 66%. ...
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Detection of Sabotage Motion by Time Series Analysis of Video

We have developed a new index, called the resilience index, that evaluates the dynamic stability of the system safety of a nuclear power plant during a severe accident by considering the ability to recover system safety functions that have become lost in the situation. In this paper, a detailed evaluation procedure for the resilience index is described. The system safety of a PWR plant during a severe accident is then assessed according to the resilience index in order to discuss the applicability of ...
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Development of Resilience Evaluation Method for Nuclear Power Plants (Part 3: Study on Evaluation Method and Applicability of Resilience Index)

We have developed a new index, called the resilience index, that evaluates the dynamic stability of the system safety of a nuclear power plant during a severe accident by considering the ability to recover system safety functions that have become lost in the situation. In this paper, a detailed evaluation procedure for the resilience index is described. The system safety of a PWR plant during a severe accident is then assessed according to the resilience index in order to discuss the applicability of ...
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Development of Resilience Evaluation Method for Nuclear Power Plants (Part 3: Study on Evaluation Method and Applicability of Resilience Index)

In this research, a new index “The Resilience Index” was proposed to evaluate the capability of nuclear power plant to recover from the situation of safety function lost. Three elements assumed to evaluate the resilience index are the achievement rate, necessary time, and probability of success of each accident management activity. The resilience index is expected to visualize the improvement of safety of each nuclear power plant against severe accidents. ...
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Development of Resilience Evaluation Method for Nuclear Power Plant (Part.1: Proposal of Resilience Index for Assessment of Safety of Nuclear Power Plant under Severe Accident)

Abstract The total system design on Nuclear Plant ensures “Nuclear safety” with making practically achievable efforts to prevent and mitigate nuclear and radiological accidents. The performance based system design with “Defence in depth (D-I-D)” has been laid out as the key means in “preventing accidents”, “controlling escalation to serious consequences”, and “mitigating impact to the public”. D-I-D is extended to the management of severe accidents, and is an approach intended to provide protection a...
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Development of Resilience Evaluation Method for Nuclear Power Plant (Part4: Concept of System Safety on Operating Nuclear Power Plants)

The total system design on Nuclear Plant ensures “Nuclear safety” with making practically achievable efforts to prevent and mitigate nuclear and radiological accidents. The performance based system design with “Defence in depth (D-I-D)” has been laid out as the key means in “preventing accidents”, “controlling escalation to serious consequences”, and “preventing harmful consequences to the public”. D-I-D is extended to the management of severe accidents, and is an approach intended to provide protection...
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Development of Resilience Evaluation Method for Nuclear Power Plant (Part4: Concept of System Safety on Operating Nuclear Power Plants)

In view of the severe consequences of TEPCO’s Fukushima Dai-ichi NPP accident, a new framework for the continuous enhancement of severe accident management (for beyond design basis accidents involving significant fuel damage) should be established for the operation of existing plants in Japan. Preparedness and response measures for addressing extreme natural disasters as large-scale earthquakes and tsunamis, and for other severe accident initiators should be formulated quickly, properly, and in good sequen...
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Nuclear Safety Assessment of Nuclear Operating Plants after Fukushima No.1 NPS Tsunami Accident

はじめに 2011 年 3 月 11 日に発生した東北地方太平洋沖地震は 日本周辺における観測史上最大の地震となり [1]、この 地震に伴い発生した津波が東京電力福島第一原子力発電 所(以下、1F)を襲った。1F は全交流電源喪失状態に陥り、 原子炉内部や核燃料プールへの注水を行えず、原子炉を 冷却できなくなったことで炉心溶融に陥り、最終的には 大気中、土壌、溜まり水、立坑、海水、および地下水へ の広範囲に渡る放射性物質の放出事故に至った。この事 故は国際原子力事象評価尺度 (INES: Internat......