For the commercialization of fast breeder reactors (FBR), it is essential to enhance the economic competitiveness by reduction of total cost by elongation of plant service period. In this point of view, it is important to establish the assessment method of integrity of aged weld joint and repair welding for the components of future long life FBR. In the present study, evolution of microstructure is evaluated for the 304SS-304SS weld joint which was used for 88,000h at 526-545°C in the French proto-typ...
英字タイトル:
Influence of FBR plant service and repair welding on microstructure and residual stress of austenitic stainless steel weld joint

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...
英字タイトル:
Fundamental Study on Applicability of Resilience Index for System Safety Assessment

In nuclear power plants, surface treatment including the shot peening is carried out after welding for the prevention of stress corrosion cracking. In this research, the authors developed evaluation systems of the persistence of compressive residual stresses due to shot peening based on the Idealized Explicit FEM which can conduct large-scale non-linear structure analyses in realistic computing time. The developed evaluation system was applied to the analysis of the compressive residual stress due to sho...
英字タイトル:
Study of behaver to relieve residual stress at the time of the shot peening

残留応力とは、読んで字のごとく、外力を負荷しない状況においても、物体内部に存在し続ける応力のことを言う。この残留応力は、例えば、工業製品の製造工程における、機械加工、塑性加工、接合、組み立てなどに起因して発生し、機械部品の寸法精度や、その疲労強度などに影響することが知られている。時に、疲労破壊を原因とした事故が報道されることがあるが、こういった疲労破壊の多くは、その破壊起点周辺の引張残留応力に起因するものが多い [1]。このように、人命にも関わる重大事故にも繋がりかねない残留応力は、「ものづくり」の分野において重要な力学パラメータの一つであり、残留応力を知ること、そしてそれを制御することは、信頼性の高い製品開発に重要である。しかし、残留応力は直接目に見ることはできないために、どこにどれだけの大きさの残留応力が発生しているかを把握することは難しい。そのため、何らかの方法により、その残留応力を定量化し可視化することが必要になる。 残留応力測定に対するニーズには、ものを壊すことなく非破壊で測定できること、実機そのもの、あるいは実機にできるだけ近い状態で測定できること、数 mm以下の高い空間分解能で応力分布の測定がで...

For the commercialization of fast breeder reactors (FBR), it is essential to enhance the economic competitiveness by reduction of total cost by elongation of plant service period. For this reason, it is needed to establish the aged weld joint integrity assessment method for future FBR compon ents. Additionally, since it is expected to employ the repair weld for aged structural components, it is essential to investigate the effect of repair weld. To investigate the influence of high temperature-long service...
英字タイトル:
Basic investigation of aging weld joint and repair weld joint integrity assessmentusing neutron residual stress measurement method

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)

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 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...
英字タイトル:
Development of Resilience Evaluation Method for Nuclear Power Plant (Part4: Concept of System Safety on Operating Nuclear Power Plants)