We have developed a new index called Resilience index, which evaluate the reliability of system safety of nuclear power plant under severe accident by considering the capability to recover from the situation the system safety function was lost. In this paper, a detailed evaluation procedure for the Resilience index was described. System safety of a PWR plant under severe accident was then assessed according to the Resilience index concept to discuss applicability of the index. We found that the Resilie...
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Fundamental Study on Applicability of Resilience Index for System Safety Assessment

Stainless steel is used in various nuclear installations as a major structural material. Tritium is produced by several nuclear reactions in these facilities. It is considered that the hydrogen isotope included tritium permeated for stainless steel through the interaction such as dissolution, diffusion and recombination, and is released on the atmosphere. Therefore, it is important to clarify permeation behavior of tritium in stainless steel from the viewpoint for improvement of the social acceptability o...
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Study on permeation behavior of hydrogen isotope in stainless steel

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)

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 ...
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. ...
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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)

A diffraction spot trace method (DSTM) was developed to measure internal stresses of materials with coarse grains. The DSTM was applied to light metals, such as aluminum alloy and magnesium alloy. In this study, validity of the DSTM was examined using high energy synchrotron X-rays of 70 keV. The specimen was a welded plate of austenitic stainless steel (SUS316L). The thickness of the specimen was 9 mm. The improved rotating slit-system was used, and PILATUS was used as an area detector. It was diffi...
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Evaluation of Welding Residual Stresses in Austenitic Stainless Steel Using Diffraction Spot Trace Method

A diffraction spot trace method (DSTM) was developed to measure internal stresses of materials with coarse grains. The DSTM was applied to light metals, such as aluminum alloy and magnesium alloy. In this study, validity of the DSTM was examined using high energy synchrotron X-rays of 70 keV. The specimen was a welded plate of austenitic stainless steel (SUS316L). The thickness of the specimen was 9 mm. The improved rotating slit-system was used, and PILATUS was used as an area detector. It was difficu...
英字タイトル:
Evaluation of Welding Residual Stresses in Austenitic Stainless Steel Using Diffraction Spot Trace Method

In Japanese BWR utilities, silicone rubber(VMQ) or fluoro rubber(FKM) has been used as a sealing material for the PCV upper flange and so on. However, these materials are not suitable for such use under the combined conditions of high-temperature steam and high-radiation dose by severe accident, so there is a possibility to reduce the sealing function that leads to a PCV flange leakage. Therefore, in the BWR plant owners recently decided to adopt an “improved EPDM“ which has excellent characteristics ...
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Performance evaluation of EPDM at elevated temperature

The spiral slit-system and DSTM (diffraction spot trace method) are under development in order to evaluate internal stresses of materials with coarse grains. The spiral slit-system was improved so that the length of the gauge volume is independent of the diffraction angle. The bending stress in the specimen with coarse grains was measured in order to confirm performance of this advanced spiral slit-system. The distribution of the measured bending stress coincided with the applied bending stress. As a r...
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Evaluation of Residual Stresses inWelded Part using Hard Synchrotron X-Rays