One of important mission of nuclear power plants (NPP) at R&D stage is to develop maintenance program for commercial reactors step by step securing safety. Basic principles of maintenance management for NPP at R&D stage were proposed. In this paper, applications for maintenance program on piping support of prototype sodium cooled fast breeder reactor Monju are studied on the basis of the proposed basic principles of maintenance management for NPP at R&D stage. ...
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Proposal of Maintenance Management of Nuclear Power Plants at R&D Stage by Taking Account of Their Features (3) Application to piping support

A maintenance management suitable to nuclear power plants (NPP) at R&D stage was discussed. Objectives of maintenance management of NPP at R&D stage were first clarified. Next, applicability of codes for maintenance management of commercial NPP to NPP at R&D stage was discussed. Then, requirements and consideration for maintenance management of NPP at R&D stage was proposed. In this paper, maintenance program for sodium valves are investigated. ...
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Proposal of Maintenance Management of Nuclear Power Plants at R&D Stage by Taking Account of Their Features (4) case study on sodium valves

We investigated the relationship between magnetic properties and the accumulation of fatigue damage at elevated temperature for SUS304 stainless steel. The strain-controlled push-pull fatigue tests at 923 K under total str ain range conditions of 0.4%, 0.5% and 0.7% were implemented. The leakage magnetic flux density was also measured before and after each fatigue test. As result, it was shown that the maximum differences in leakage magnetic flux density before and after the fatigue test subsequently incre...
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Evaluation of Initial Fatigue Damage of SUS304 Stainless Steel at Elevated Temperature by a Magnetic Method

Two magnetic methods are proposed for the evaluation of initial degradations of type 304 stainless steel in stress corrosion cracking (SCC). The first one is the measurement of the distribution of chromium depletion by means of a magnetic force microscope (MEM). MEM observations are performed for some samples sensitized in various conditions, and the obtained results coincide with the expected ones from the chromium behavior. Moreover, the phase distributions in the solution-annealed and sensitized states a...
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Evaluation of Initial Degradation in Stress Corrosion Cracking by Magnetic Methods

A heat-resistant flux gate magnetic sensor has been developed. Permendur, which has high Curie point, is employed as the magnetic core material and the detection method of the external magnetic field is modified. The characteristics of the developed magnetic sensor up to 500 oC were evaluated. The sensor output increased linearly with the external magnetic field in the range of ±5 G and the standard deviation at 500 oC was about 0.85G. ...
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Development of Heat-resistant Magnetic Sensor

米国機械学会（ASME）では、従来からリスク情報を活用するための規格基準類や、非軽水炉型革新炉を対象に含めた維持規格の開発整備が進められており、設計分野でも非原子力分野も対象に含め、リスク情報を活用し設計の合理化を目指す規格の新規策定のための検討が精力的に行われている。このうち、著者が開発整備に関わっているCode Case N-875及びSection XI, Division 2について概要を紹介する。...

To realize long-life fast breeder reactor (FBR) plants, it is important to develop a precise estimation method of metallurgical microstruct ure change before crack initiation. For estimating the metallurgical microstructure change related to degradation in commercial FBR plants, the change of magnetic property is focused on. Austenitic stainless steel is paramagnetic, but the magnetic flux density changes as creep damage at 773K or 823K. Finally, it is possible to detect the metallurgical microstructure c...
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Magnetic change in austenitic stainless steels subjected to long term creep damage

A magnetic sensor which can be applied to measurement at elevated temperature was newly developed. It is a kind of flux gate magnetic sensor. Permendur was employed for a magnetic core instead of Permalloy which is commonly used because Permendur has much higher Curie point, about 1000oC. Heat resistant ceramic coating Cu wires were used for coils. External magnetic field is detected by shift of peak position of differential permeability during induction of triangular excitation current. A magnetic co...
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Development of High Temperature Magnetic Sensor

This paper describes the outline of the guidelines on structural reliability evaluation for the passive components of the fast breeder reactor (FBR). The guidelines are now being prepared by the working group for the system based code in the Japan society of mechanical engineers. They consist of five chapters, which are “General rules”, “Reliability evaluation”, “Failure scenario setting”, “Modeling”, and “Failure probability calculation”, respectively. In the chapter of “Reliability evaluation”, the g...
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Development of Guidelines for Structural Reliability Evaluation for FBR

Abstract This paper describes a procedure of structural reliability evaluation of passive components of fast breeder reactors for a failure due fatigue-creep interaction damage, and also reports results of benchmark evaluation conducted by using two independently developed codes. The s tructural integrity of a reactor vessel was evaluated deterministically and probabilistically. The results estimated by two codes agree well for oth of deterministic and probabilistic evaluations, which shows that these cod...
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Benchmark Evaluation of Structural Reliability Evaluation Codes for FBR