Proceedings of the 4th International Conference on Fatigue of Nuclear Reactor Components APPENDIX 4

NEA/CSNI/R(2017)2/ADD1
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International Conference on Fatigue of Nuclear Reactor Components on 28 September-1 October 2015 in Seville, Spain.

In this work, a complete algorithm for monitoring fatigue was developed for nuclear components; in particular, a feedwater nozzle of a BWR reactor was studied. Firstly, a methodology and an algorithm was developed which is capable of monitoring the actual fatigue of a component in service by means of mathematical models during its lifetime. The mathematical models use transfer and influence functions and are based on Duhamel’s principle. Discrete convolution of the functions was done by numerical analysis. Influence and transfer functions were obtained with a 3D FE model of the nozzle. Combination of thermal and structural 3D models was needed to obtain them. This new method was compared in terms of stress intensity with the results of FE models for the complete transient, showing good correlation. Finally, a methodology was also developed and computed for calculating CUFs in the component critical zones with regards of environmental effects during service life taking into account two different calculation options.