It is shown that analysis on the distribution of fracture initiation sites is useful for examination of the fracture condition in steel. As an example of such analysis, the distribution of fracture initiation sites in fracture toughness test is employed to estimate the shape parameter of the fracture probability, i. e. the m-value in the Beremin model.

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The effective far-side magnetic flux leakage technique for the inspection on the bottom plates of oil tanks was proposed as a quantitative evaluation method on local corrosion. Based on the technique, the flaw characterization obtained from the inspection data under the saturation magnetization by using the neural network was presented, and its effectiveness has been proven in this paper. In addition, the practicality of the proposed neural network has been confirmed by its successful application to a large steel plate such as the bottom plates of oil tanks when original data was corrected with the result of the finite element simulation. Further improvement on the accuracy of quantitative evaluation on natural flaws can be expected by training neural network with different signals.

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The verification test of machine diagnosis techniques was carried out by Japan Power Engineering and inspection Corporation, and a system called as the RET (Residual Life Evaluation of Thermal Power Plants) system was developed as the result of this activity. The RET system can evaluate the primary damage of equipments in boiler or turbine using several residual life evaluation methods. The RET system provides valuable function for the residual life evaluation. However, this system is not necessarily utilized widely. In this study, online version of the RET system is developed for the purpose of populization of the RET system. The online RET system can evaluate the primary damage of the equipments in boiler or turbine without any extra application, and is easy to reflect new information.

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