A New method for non-destructive testing (NDT) of surface-breaking tight cracks based on laser-induced nce acoustic waves (SAW) is proposed. A Q-switched Nd:YAG laser is used to generate SAW through Live interaction between material and the laser pulses. The SAW is probed by an optical interferometer as a o displacement of the surface. A state-of-the-art technique in laser-ultrasonic NDT is reviewed: that is the < depth measurement by using fr equency analysis of SAW transmitted through cracks. The techni...
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Laser-Ultrasonic Non-Destructive Testing:hniques and Applications in Nuclear Industry

A new method for non-destructive testing（NDT）of surface-breaking tight cracks based on laser-induced surface acoustic waves（SAW）is proposed. A Q-switched Nd:YAG laser is used to generate SAW through ablative interaction between material and laser pulse. The SAW is probed by an optical interferometer as a micro displacement of the surface. A state-of-the-art technique in laser- ultrasonic NDT is developed: that is the crack depth measurement by using frequency analysis of laser-induced SAW transmitted throug...
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Laser-ultrasonic study of micro crack sizing and its application to nuclear reactor internals

Welding is an essential industrial process in the fabrication of a variety of products and also in maintenance activities. Although most welding processes have already been automated, the high reliability of the manual welding fabrication is still in demand. In this paper the necessity of the in-process monitoring of the performance of manual welders is addressed in order to assess the skill of a manual welder in the workshop environment. The behavior of welders with different skill levels was monitored dur...
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MONITORING AND ANALYSIS OF THE BEHAVIOR OF WELDERS DURING MANUAL WELDING

In order to study the influence of welding condition on the detectability of flaws in Ni based alloy by UT, we lding conditions, such as heat input, magnetic stirring and weaving were changed. Flaws in small heat input we ld joints was difficult to be detected because of the presence of high noise. On the contrary, welded joints m ade with large heat input and weaving showed lower noise and EDM notches in these joints were easily detected....
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The Influence of Welding Condition on Flaw Detectability by Ultrasonic Test in Ni Based alloy welds.

The sodium leak accident in a secondary main cooling system of prototype fast breeder reactor Monju was occurred on December gth in 1995, and the Monju has stopped for 14 years since that. The confirmation of Monju systems and components integrity toward early restart of Monju was planned and started in 2006. The plan consists of inspection of components including repair, renewal and improvement and systems tests. About 90% of the integrity confirmation was comp leted at the end of May 2009. The integrity ...
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Confirmation of Monju systems and components integrity and Maintenance Program toward Monju restart

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...
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Influence of FBR plant service and repair welding on microstructure and residual stress of austenitic stainless steel weld joint

Shot peening process is countermeasures to prevent stress corrosion cracking in nuclear power plant components. It is necessary to confirm whe ther the compressive residual stress exerted by stress improvement processes can be sustained under operation environment. In order to evaluate stability of compressive residual stress, the nickel base alloy welded specimen was subjected to thermal cycles 10 times where the peak temper ature is 593 K. On the other hand, carrying out shot peening increases the interg...
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Change of compressive residual stress and intergranular corrosion resistanceafter thermal history in nickel base alloy welds by shot peening

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...
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Study of behaver to relieve residual stress at the time of the shot peening

When their Cr contents were increased to the same level as those of the alloy 82(18-22mass%Cr), the weld metals of alloy 182(13-17mass%Cr) sustained only slight SCCs in the as-welded state, and no crack was detected after the post weld h eat treatment (SR+LTA) of stress relief annealing at 893 K followed by aging at 673 K. These results suggest that the higher Cr content of the alloy 82 is responsible for its higher resistance to SCC than that of the alloy 182. The carbi de, Nijo(Mn, Cr).Siz (G phase) was ...
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Effect of Chromium Content on Stress Corrosion Cracking of Shielded Metal Arc Weld Metalfor 600 Type Alloy in High Temperature Pressurized Pure Water

The SCC susceptibility of the weld metal was evaluated from the maximum depth and number of cracks occurring during the CBB (Creviced Bent Beam) test in high temperature pressurized water using plate specimens cut from shielded metal arc weld metals. When the specimen received a heat treatment consisting of stress relief annealing (SR) for 72 ks at 893 K and subsequent ageing (LTA) for 720 ks at 673 K, however, the significant influences of the increases in C and Nb contents on the SCC susceptibility were...
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Effects of C and Nb Contents on Stress Corrosion Cracking of Shielded Metal Arc Weld Metalfor 600 Type Alloy in High Temperature Pressurized Pure Water