Modified 9Cr-Mo steel is a candidate structural steel for demonstration fast breeder reactors (FBR's). Due to low thermal activatio n, the steel can maintain steady-state deformation during long-term creep. The creep strength of its weldment is lower than that of the base metal. Because of different creep strain rate in the solidified weld metal and heat-affected zone (HAZ), creep deformation in HAZ can be lowered but maximum principal stress augmented in fine-grained HAZ to cause detrimental Type IV crack...
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FEM Analyses of Creep in Welded Modified 9Cr -1 Mo Steel Considering Constraint Effects Induced by Anisotropic Microstructures

The present study has investigated plasticity-induced martensitic phase transformation in fatigue of unnotched SUS304 plates. Martensitic phase transformation occurred in uunotched SUS304 plate specimens fatigued at room temperature in air. Volume fraction Va of a'martensite in the uunotched potion of fatigued s pecimens was measured by ferrite scope. The relations between the maximum value of Vas Va’max, and the number of load cycles N were represented by reverse sigmoidal curves for all the applied stres...
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Evolution of Volume Fraction of Plasticity-Induced Martensitic Phase during Fatigue Process of SUS304 Stainless Steel at Room Temperature in Air

The present paper proposes new creep life prediction methods that can be used in situ as an in-service inspection tool for the condition based monitoring of high-temperature structure components of 316FR stainless steel. The methods are based on two types of the modified theta methods and the combination of the modified and omega methods are applied to creep deformation data measured in the creep tests made at different applied stress levels at 823-923 K in air. Creep lives were predicted by the propos...
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In Situ Creep Life Prediction Methods for Austenitic Stainless Steel 316FR

We have explained the planning method of maintenance schedule to ensure the high reliability at minimum cost. At the present, maintenance costs higher than re quired. This comes from mismatch between judgment of importance to be repaired and properties of equipment posses. Property means specification, potential loss or urgency that equipment possesses. To solve this subject, properties of equipment have to be evaluated suitably, and then maintenance management density as w ell. The important matter is est...
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How to establish maximized optimized Plant Maintenance at low cost

Many Swagelok connections are used in the instrumental tube pipe of Nuclear power plant because Swagelok conne ion is easy to put on and take off quickly. Although Swagelok connection is easy handling, it occurs very sma ll amount of leakage in some case. For the purpose of development of quick repair method for small amount leak e of Swagelok connection, we considered the base technique about the miniature cramp for Swagelok connection....
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Development of Miniature Cramp for Swagelok Connection Temporary Repair

An in-vessel repairing machine for Fast Breeder Reactor (FBR) needs to work under liquid sodium environment. W e have been worked the development of a repairing machine based on Friction Stir Welding (FSW) method. The expe riment of repairing artificial crack in liquid sodium was successful by prototype FSW-repairing machine. In th is report, we also introduce our studies on the particular problems of FSW-repairing such as burr and end hole....
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Development of a repairing machine based on Friction Stir Welding (FSW) for the sodium coolant Fast Breeder Reactor

The present study investigates plasticity-induced martensitic transformation around fatigue cracks in single V-groove butt-welded SUS304 plates at room temperature in air. Distributions of a' phase volume fraction Va around fatigue cracks were measured with ferrit e scope. The results were compared with the distributions of vertical magnetic flux density B, above fatigue cracks in welded specimens magnetized by a strong electromagnet. It was revealed that the B, distributions reflected the spatial distribu...
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Non-Destructive Evaluation of Fatigue Cracks in SUS304 Stainless Steel Weldment by Using Plasticity-Induced Martensitic Transformation

Today, many troubles such as big accidents, human errors, active concealment, etc. are occurring frequently, and have had a bad influence on the reliability and security of a human life. As a cause of these problems, lack of information and knowledge, lack of tactics to safety ensuring, lack of the strategy to safety, etc. are pointed out. To solve these problems as mentioned, the technology concerning risk management immediatel y needs to be systematized. As such a technical system, we have proposed the c...
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Plant Engineering and Maintenance based on Risk Evaluations (Part 2) Development of the Technology Knowledge Infrastructure

Management and maintenance tools are now greatly available for contributing reduction of maintenance cost and time. These tools surely give us much benefit, but are only for maintaining reliabilities of the equipment. Reliability of the plant dep ends on the design and actual operating conditions. Accordingly, the matter to do first is to consider facilities in the range of the plant life cycle. This brings the result that “process property” and “equipment property” are required besides “ equipment functio...
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Application of Plant Technology Knowledge Infrastructure to Plant Engineering and Maintenance

Today，many troubles such as big accidents, human errors, active concealment, etc. are occurring frequently, and have had a bad influence on the reliability and security of a human life. As a cause of these problems, lack of information and knowledge, lack of tactics to safety ensuring, lack of the strategy to safety, etc. are pointed out. To solve these problems as mentioned, the technology concerning risk management immediately needs to be systematized. As such a technical system, we have proposed th...
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Development of the Technology Knowledge Infrastructure for the Risk Management