Developing a precise nondestructive estimation method of material degradation before crack initiation will contribute to enhancement of safety and economical efficiency of a fast breeder reactor plant. Magnetic property is expected to be an effective indicator. In this study, fatigue t ests on SUS304 stainless steel at 650°C were conducted until transition hardening region, 25% and 50% of the number of cycles to fracture and the distribution of magnetic flux density from each sample was measured to reveal ...
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Magnetic Property Change of SUS304 Stainless Steel at Initial State of Fatigue Damage in High Temperature Environment

Developing a precise nondestructive estimation method of material degradation before crack initiation will contribute to enhancement of safety and economical efficiency of a fast breeder reactor plant. Magnetic property is expected to be an effective indicator. In this study, fatigue tests on SUS304 stainless steel at 650°C were conducted until transition hardening region, 25% and 50% of the number of cycles to fracture and the distribution of magnetic flux density from each sample was measured to r...
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Magnetic Property Change of SUS304 Stainless Steel at Initial State of Fatigue Damage in High Temperature Environment

This study proposes a predictive monitoring method for irradiation assisted stress corrosion cracking (IASCC) of austenitic stainless steels. High purity model austenitic stainless steel s were irradiated up to ldpa or 5dpa in JRR-3. IASCC susceptibility of the irradiated specimens was determined by scanning electro microscopy (SEM) on fractured surface of the specimens after slow strain rate tensile (SSRT) testing in high temperature water simulating boiling water reactor (BWR) conditions. Magnetic proper...
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A Study of Testing Method for Predictive-Monitoring of IASCC Susceptibility

We are developing a method for evaluation of irradiation damage on structural materials in nuclear plants by using change in magnetic flux density due to irradiation damage. In this study, the magnetic flux density measurement technique has been improved by introducing a new magnetizer which enables local magnetizing by contacting the sample surface. We can magnetize samples, especially ferromagnetic samples, more precisely co mpared to the existing method. Furthermore, the new method can remove many limi...
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Improvement of Magnetic Flux Density Measurement Techniquefor Irradiation Damage Evaluation

The remote operated vibrating sample magnetometer (VSM) for neutron irradiated samples has been developed. The maximum range of applied magnetic field is more than ±0.5/?0 A/m, and the resolution of magnetic moment is higher than 5 ×10-8 A?m2. The hysteresis loops of neutron irradiated samples were measured by this VSM, and the relationships between dose, which is one of epresentative irradiation parameter, and magnetic properties such as magnetic coercive force were examined. As result, it was revealed tha...
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Development of Remote Operated Vibrating Sample Magnetometer for Evaluation of Irradiation Damage

The remote operated vibrating sample magnetometer (VSM) for neutron irradiated samples has been developed. The maximum range of applied magnetic field is more t han ￡0.5/10 A/m, and the resolution of magnetization is higher than 5 x10-A'm2. The magnetization curves of neutron irradiated samples were measured by this VSM , and the relationships between dose, which is one of representative irradiation parameter, and magnetic properties such as magnetic coercive force. As result, it was revealed that there a...
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Development of Remote Operated Vibrating Sample Magnetometerfor Evaluation of Irradiation Damage

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

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

Proper management of neutron irradiation damage on structural materials is important to ensure the Lealth of long-life fast breeder reactor (FBR) plants. Therefore, the effective index f or irradiation amage or the combination of those should be developed. In this study, the effects of dose, helium, nd the ratio of helium to dose on tensile and creep properties of FBR gra de type 316 stainless steel were investigated in the assumed irradiation damage range of FBR structural materials, that is, up to bout 1...
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R & D on Irradiation Damage Management Technology for FBR Structural Materials 髙屋 茂 Shigeru TAKAYA