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)

In August 2004, a pipe rupture accident occurred at The Kansai Electric Power Company Mihama Unit3. Japan Society of Mechanical Engineers (JSME) recognized that it was an urgent problem to settle the rules on Pipe Wall Thinning Management by Fluid Flow. JSME enacted “rules on Pipe Wall Thinning“ that stipulates the basic requirements of pipe wall thinning management, considering from these situations. In 2006 , JSME enacted the “rules on Pipe Wall Thinning Management for PWR Power Plants” (JSME S NG1-2006...
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Analysis of Data on Pipe Wall Thinning Phenomena by Fluid FlowIn Pressurized Water Reactor Plant

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 ...
英字タイトル:
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 ...
英字タイトル:
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. ...
英字タイトル:
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)

The resilience index has been proposed to evaluate the capability for recovering safety performance of systems subjected severe accident for nuclear power plants. In this study, a failure probability assessment model was developed for the resilience evaluation of static components in nuclear power plants. This model took into consideration the effect of material degradation caused by low-cycle fatigue. Crack initiation due to fatigue damage was assumed and its depth was determined from the magnitude of f...
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Development of Evaluation Method for Resilience Index in Nuclear Power Plant (Part 2: Development of Reliability Assessment Model Considering Degradation of Static Components)

Resilience index is proposed to be applied to evaluate the capability to recover safety performance of systems under severe accident of nuclear power plant. This study developed the failure probability model of equipment by low-cycle fatigue and applied the model to the reliability analysis for degradation of static components in resilience index, ...
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Development of Resilience Evaluation Method for Nuclear Power Plant (Part 2: Study on Reliability Analytical Method for Degradation of Static Components)

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)

Pipe wall thinning caused by FAC (Flow Accelerated Corrosion) and LDI (Liquid Droplet Impingement)is managed through the measurement of pipe wall using UT (Ultrasonic Test) and the replacement of thinning element until reaching allowable limit in order to prevent pipe failure in Japan. Minimum wall thickness of design codes is applied to the allowable limit of pipe wall thinning management. On the other hand, the thinning area is localized in pipe wall caused by FAC and LDI, so the integr ity of piping sys...
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Application of local thinning criteria in pipe wall thinning management of nuclear power plant

After Fukushima-Daiichi accident, nuclear power plants are highly requested to enhance safety against severe accident. It is important to prevent fatigue failure for operating nuclear power plants, especially pressure boundary of compon ts to ensure safety. This paper studies the failure database of nuclear power plant in Japan (NUCIA) and extracts the events caused by fatigue failure. Fatigue failure can be classified according to fatigue mechanism such as mechanical vibration, fluid vibration, high-cycl...
英字タイトル:
Study of fatigue failures to improve safety based on the analyses of failure database in Japanese nuclear power plant